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Dietary factors affecting aflatoxin Bi carcinogenicity

Dietary factors affecting aflatoxin Bi carcinogenicity
Dietary factors affecting aflatoxin Bi carcinogenicity

Mal J Nutr 3:161-179, 1997

Dietary factors affecting aflatoxin Bi carcinogenicity

Ayub MY1 & Sachan DS2

1 Department of Food Science and Nutrition, Faculty of Life Sciences, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor.

2 Department of Nutrition, College of Human Ecology, University of Tennessee, Knoxville, Tennessee 37996, U.S.A.

ABSTRACT

This review paper describes briefly on the history of aflatoxins, the metabolism of aflatoxin B1 (AFB1) that leads to the activation and detoxification of AFB1, and the findings of some of the studies relating to food nutrients and additives, and drugs on AFBJ carcinogenicity and detoxification. Aflatoxins have been linked to many public health problems, especially to liver cancer incidences, in different parts of the world. Many studies have shown the potential of dietary factors modulating the formation of AFB1 - DNA adduct, the initial and important step of AFB1 carcinogenesis process. Among the food nutrients that have been shown to reduce the binding of AFB1 to DNA are vitamin A, vitamin C and riboflavin. On the contrary, vitamin E and β-carotene increase the DNA binding. Choline-deficient animals when subjected to multiple doses of AFB1 had higher amount of the DNA adduct being formed than the choline-sufficient animals. Carnitine supplement, feed restriction, and some vegetables and their extracts can also decrease the AFB1 -DNA adduct formation. The observed and proposed mechanisms for the reduction include the inhibition of bioactivation of AFB1 and induction of glutathione S-transferase activity that detoxify the activated AFB1. However, more research is needed before nutritional recommendations could be given to the public to control AFB1 toxicity and carcinogenicity.

INTRODUCTION

History of Aflatoxins

Aflatoxins are a group of mycotoxins produced by the molds Aspergillus flavus and A. parasiticus. They are commonly found to contaminate food and feeds, such as milk, corn, peanuts, cottonseed, rice, and barley, grain-fermented beverages and edible animal tissues (Park & Pohland, 1986).

Aflatoxins were first discovered in 1960 when a series of outbreaks in poultry and fish occurred in different parts of the world. One of the worst outbreaks was the “Turkey-X” disease that caused the deaths of many turkies, ducklings, and chicks in Britain (Blount, 1961). Consumption of aflatoxin-contaminated Brazilian groundnut meal was implicated in the disease. At the same time, feeding of contaminated corn, peas and cottonseed to farm animals and fish were reported to cause outbreaks analogous to the “Turkey-X” disease elsewhere (Palmgren & Ceigler, 1983).

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Experiments conducted on the contaminated Brazilian peanut meal resulted in the isolation of A. flavus, and when the fungus was inoculated into untainted peanut meal, the fungus produced toxins similar to those found in the contaminated meal (Sargeant et al., 1961). The isolated toxins were named “aflatoxin.”

The current technology and knowledge can neither totally inhibit aflatoxins synthesis by the molds nor completely eliminate them once they are produced. As a result, the significance of aflatoxins contamination has long been recognized, and limits in agricultural commodities have been set since 1965. In 1993, the International Agency for Research on Cancer upgraded AFB1 from a Group II to a Group I human carcinogen classification (IARC, 1993).

Structure and Toxicity

Aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) are the four main naturally-occurring aflatoxins. The letters B and G refer to the aflatoxins’ color under UV light (B for Blue; G for Green), and the subscripts 1 and 2 refer to their relative positions on a developed thin-layer chromatography plate. The structure of aflatoxins consists of a coumarin nucleus attached to a bifuran and either pentanone (AFB1 and AFB2) or a six-membered lactone (AFG1 and AFG2) (Figure 1). AFB1 and AFG1 are more toxic to rats and ducklings as compared to AFB2 and AFG2 (Wogan, Edwards & Newberne, 1971). As for carcinogenicity, AFB1 is more carcinogenic than AFG1, while AFG1 is more carcinogenic than AFB2 (Shoenhard et al., 1981). The main target organs for AFB 1 toxic and carcinogenic effects are the liver and kidney.

Figure 1: Structures of naturally occurring aflatoxins

Dietary factors and aflatoxin B, carcinogenecity

AFB1 Metabolism and Carcinogenicity

AFB1 is the most abundant and toxic form of all naturally occurring aflatoxins. AFB1 represents 75% of all aflatoxins found in contaminated food and feeds. It is hepatotoxic (O’Brien et al., 1983), hepa-tocarcinogenic(Adamson et al., 1979), and teratogenic (Bassir & Adekunle, 1970) to various animal species. AFB1 is first metabolized (Phase I metabolism) mainly by the cytochrome P-450 enzyme (CYP450) system found in the microsome. This metabolism will produce a variety of metabolites such as AFB1-epoxide and hydroxylated metabolites (AFM1, AFP1, AFQ1, and aflatoxicol).

Figure 2: AFB1-DNA adduct formation AFB1-epoxide is a very reactive and unstable metabolite of AFB1 that will bind to cellular DNA, RNA, and protein. The formation of AFB1-DNA adduct is highly correlated to the carcinogenic effect of AFB1 in both animal and human cancer cases (Thabrew & Bababumi, 1980; Wogan et al., 1971; Alpert et al., 1971; Groopman, Cain, & Kensler, 1988). The “Virtually Safe Dose” of AFB1 is estimated at 0.016 ng/kg/day (reviewed by Eaton & Gallagher, 1994).

The major AFB1-DNA adduct formed with liver DNA is aflatoxin B1-N7-guanine (AFB1-N7-gua) (Essigmann et al., 1977). This adduct is unstable and subjected to decomposition. The major decomposed derivatives of AFB1-N7-gua in rat liver are the imadozole ring-opened AFB1 formamido-pyrimidine adducts, namely AFB1-N7-FAPY major and minor (Croy & Wogan, 1981) (Figure 2). AFB1-N7-FAPY adducts are more stable, and their accumulation in liver DNA is related to the subsequent reduction of AFB1 -N7-gua adduct level.

Hepatocellular carcinoma (HCC) is a major health problem in China where each year approximately 110,000 patients are diagnosed with it. The HCC cases in China account for almost 45% of HCC incidences in the world (Parkin, Sternward & Muir, 1984). The mortality rate for HCC is more than 95%. Excluding other risk factors, the consumption of AFB1-contaminated food such as corn, soya-based products, and peanut oil was correlated

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(r = 0.55) to the HCC fatality rates in people living in ten Chinese villages that were studied. See Yu (1995) for a current review of HCC in China.

The phase I AFB1 metabolites may undergo phase II biotransformation involving the enzymes glutathione S-transferase (GST), β-glucuronidase, and/or sulfate transferase which produce con-jugates of AFB1-glutathione, AFB1-glucuronide, and AFB1-sulfate, respectively. The major conjugate of AFB1-epoxide identified is the AFB1-glutathione conjugate (Monroe & Eaton, 1987; O’Brien et al., 1983). This conjugation is the principal detoxification pathway of activated AFB1 in many mammals. It has been accepted that cytosolic GST activity is inversely correlated to susceptibility of the several animal species to AFB1 carcinogenicity (Eaton & Gallager, 1994; Neal, 1987).

The hydoxylated (AFM1 and AFQ1) and O-demethylated (AFP1) metabolites of AFB1 can undergo glucuronidation and sulfation. Glucuronidation, catalyzed by liver microsomal UDP-glucuronyl transferase (UDPGT), has been reported for a variety of endogenous and foreign compounds (Burchell & Coughtrie, 1989). These conjugations results in formations of water-soluble aflatoxin esters that are excreted in the urine or bile (Hseih & Wong, 1982).

AFB1 and Diet Interactions

Species differences, nutritional manipulations, health status, drugs, and chemical treatments affect AFB1 biotransformations, and thus, its potency. There are many reports on the effects of various foods or nutrients and xenobiotics on AFB1-macromolecule adducts formation. Obviously, the major objectives of these studies were to determine if and how those nutrients or xenobiotics could affect adducts formation, especially DNA adduct. Tables 1 and 2 summarize some of the effects of nutritional factors and drugs or xenobiotics on the formation of AFB1-DNA adduct.

Table 1: Influences of dietary nutrients on AFB1-DNA adducts formation.

Reference

System

Compound* Test

Increase (↑) /

Decrease (↓)

Low Protein Rat liver ↑Mandell et al. (1992)

Low fat (high carbohydrate) Rat liver ↑Nyathi et al. (1993)

Rat liver NSE*Marzuki & Norred (1984)

Fat

(saturated or unsaturated)

Essential oils Rat liver microsome ↓Hashim et al. (1994) Vitamin A Rat liver ↓Bhattacharya et al. (1989)

Rat liver microsome ↓Aboobaker et al. (1997)

Rat liver NSE Chen et al. (1982)

hepatocyte

Woodchuck

↓Yu et al. (1994)

hepatocyte

β-carotene Woodchuck

↑Yu et al. (1994)

liver ↓Gradelet et al. (1998) Carotenoids Rat

Vitamine E Woodchuck hepatocyte ↑Yu et al. (1994)

liver ↓Webster et al. (1996) Riboflavin Rat

Vitamin B6Rat liver microsome NSE Bhattacharya et al. (1984) Thiamin Rat liver microsome NSE

Vitamin C Woodchuck hepatocyte ↓Yu et al. (1994)

Lipotropes (deficient) Rat liver ↓Campbell, Hayes &

Dietary factors and aflatoxin B, carcinogenecity

Newbeme (1978) Carnitine Rat liver ↓ Sachan & Ayub (1992) Choline (deficient)

Bhattacharya et al. (1984) Rat liver - Single AFB 1 dose

- Multiple AFB 1 doses NSE ↑ Schrager et al. (1990) Schrager et al. (1990) Copper Rat liver microsome ↓ Bhattacharya et al. (1984) Selenium (Excess or deficient)

Rat liver ↓ Chen et al. (1982)

Selenium Chick liver NSE Chen et al. (1982) Selenium Hamster ovary cells NSE Shi et al. (1995)

Feed restriction Rat liver ↓ Pegram et al. (1989) Gao & Chou (1992) Chen et al. (1995) Chou et al. (1997) Indole-3-carbinol Trout liver ↓ Dashwood et al. (1989) Trout liver microsome ↓ Takahasi et al. (1995) R-goitrin Rat liver ↓ Chang & Bjeldanes (1987) Curcumin Rat liver microsome ↓ Firozi et al. (1996) Garlic compounds Rat liver S-9 fraction ↓ Tadi, Teel & Lau (1991) Green tea Rat liver ↓ Guozhong et al. (1997) Coffee extracts Rat liver fractions Cavin et al. (1998)

*NSE, no significant effect

Table 2: Influences of food additives and drugs on AFB 1 -DNA adducts formation.

Compound * Test System Increase (↑) / Decrease (↓) Reference

BHA Rat liver microsome ↓ Bhattacharya et al. (1984) Rat liver ↓ Chang & Bjeldanes (1987) Trout liver NSE ** Goeger et al. (1988) Rat and mouse livers ↓ Monroe & Eaton (1987) BHT Rat liver microsome ↓ Bhattacharya et al. (1984) Cortisol Rat liver ↑ Chentanez et al. (1984) Crocetin Fibroblast cell ↓ Wang et al. (1991a) DDB Rat liver ↓ Liu et al. (1995) Ethoxyquin Rat liver ↓ Kensler et al. (1986) Ethanol Rat liver ↓ Toskulkoa & Glinsukon (1986)

Geniposide Rat liver ↓ Wang et al. (1991b) Rat liver microsome ↓ Wang et al. (1992) Phenobarbital Rat liver ↓ Lotlikar et al. (1989) Dithio- Carbamate Rat liver ↓ Gopalaswamy et al. (1998)

* BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; DDB; dimethyl-4-4’ dimethoxy-5, 6, 5’6’-dimethylenedioxy biphenyl-2,2’ dicarboxylate.

**NSE no significant effect

Fat-soluble vitamins

Ayuh MY & Sachan DS

A number of vitamins and vitamin analogs have been tested on AFB1-macromolecule adduct formation. Bhattacharya and coworkers (1984; 1987) reported comprehensive studies on the effects of various vitamins on in vitro adducts formation.

Vitamin A supplemention in rats inhibited AFB1-DNA binding (Bhattacharya, Prabhu & Aboobaker, 1989). The protective effects of retinoids such as retinol, retinal, retinoic acid, and retinal esters on AFB1 carcinogenicity were due to inhibition of AFB1-DNA adduct formation by affecting the CYP45O systems resulting in less epoxide being formed (Bhattacharya et al., 1984; Aboobaker et al., 1997). Retinal had the same inhibitory effect on the formation of AFB1 -protein adducts (Bhattacharya et al., 1989). Vitamin A has been shown to induce the activity of glutathione S-transferase, thereby enhancing the detoxification of AFB1-epoxide. On the other hand, vitamin A deficiency decreased glutathione S-transferase activity.

A combined deficiency of vitamin E and selenium decreased AFB1 binding to DNA, RNA, and protein (Chen et al., 1982). Vitamin E and menadione (a water-soluble synthetic vitamin K) have been found to prevent AFB1 -induced mutagenesis in the Ames bacterial system (Raina & Gurto, 1985). β-carotene and vitamin E increased DNA adduct formation in woodchuck hepatocytes (Yu et al., 1994).

Water-soluble vitamins

Riboflavin, riboflavin-5’-phos-phate (FMN), and flavin adenine dinucleotide (FAD) inhibited AFB1-DNA adduct formation in vitro. Riboflavin was reported as the most effective of the three vitamins (Bhattacharya et al., 1984). It has been recently suggested that the mechanism for the riboflavin effect is its ability to induce the enzymes involved in repairing damaged DNA (Webster, Gaude & Bhattacharya, 1996).

Vitamin C, vitamin B6 and thiamin had no significant effect on DNA adduct production (Bhattacharya et al., 1984). However, vitamin C, B6, and folic acid inhibited mutagenesis in bacterial systems (Bhattacharya et al., 1984; Bhattacharya et al., 1987). The inhibition by vitamin C was not as great as with the fat-soluble vitamins.

In a study employing woodchuck hepatocytes to find the role of vitamins A, C, and E, and β-carotene on the initiation of AFB1-induced carcinogenesis, the workers found that vitamin A was more effective than vitamin C in inhibiting DNA adduct formation. In contrast, vitamin E and β-carotene enhanced the binding (Yu et al., 1994). However, a current study reported that carotenoids were effective in lowering AFB1-DNA adduction in rats. This reduction was due to the enhancement of the detoxification of the activated AFB1 (Gradelet et al, 1998). Therefore, these results suggest that different antioxidant vitamins may effect AFB1-DNA binding differently.

Amino acids

There are conflicting reports on the effects of different amino acids on AFB1 carcinogenesis. A diet marginally deficient in methionine (which was also deficient in choline and lacking in folacin) depressed DNA and RNA adducts formation in rat liver. Protein adduct formation was

Dietary factors and aflatoxin B, carcinogenecity

not affected by the diet. The inhibition of AFB1-nucleic acid adducts in the marginally lipotrope-deficient diet was due to the decrease in the activation of AFB1 and not due to an increase in glutathione levels (Campbell, Hayes & Newberne, 1978). A choline and methionine-deficient diet fed rats showed no significant AFB1 dose-response changes in serum biochemical parameters or liver pathology compared to the complete amino acid diet (Mehta et al., 1993). These two studies treated the rats with a single dose of AFB1.

Schrager et al (1990) found that a single dose of AFB1 did not affect the DNA adduct concentration in both choline-deficient and control animals. However, when multiple doses of AFB1 were administered, the AFB1-DNA adduct levels were significantly higher in the rats fed a choline-deficient diet than in the rats fed with a control diet. An earlier report also found that marginally deficient lipotrope diets induced AFB1 tumorigenesis in rats (Rogers & Newberne, 1969).

L-carnitine supplementation in rats has been found to decrease AFB1-DNA binding in rats (Sachan & Ayub, 1992). Carnitine, a quarternary amine whose structure is quite similar to choline, can also affect AFB1 binding to hepatic RNA and protein (Table 3). The total amount of AFB1 present in the liver and kidney were not significantly different between the carnitine supplemented and control animals. However, the concentrations of AFB1 were higher in the plasma of carnitine supplemented rats than the non-supplemented rats. Recently, we found that carnitine inhibited the microsomal activation of AFB1 and on the binding of activated AFB1 to exogenous (calf thymus) DNA (Ayub & Sachan, unpublished data). This maybe the mechanisms for carnitine reducing the AFB1-DNA adducts formation. We had also shown that carnitine ameliorated the earlier signs of acute toxicity of AFB1, such as the elevation of total lipid concentration in the liver and the decrease in total lipids and triacylglycerol concentrations in the plasma (Sachan & Ayub, 1991; Sachan & Ayub, 1992).

Sulfur-containing amino-acids such as cysteine, N-acetylcysteine, cystine, methionine, and glutathione inhibited AFB1 mutagenicity in microbial systems. Cysteine and Nacetylcysteine were more potent inhibitors than glutathione. The investigators suggested that the inhibition was due to amino acids affecting the synthesis of AFB1-epoxide (Shetty Francis & Bhattacharya, 1989).

Table 3: Effects of L-carnitine supplement on aflatoxin B1-macromolecules adducts formation in rat liver 6-h post-aflatoxin B1 administration1

Group

Parameter Control

L-Carnitine2Difference (%)

pmol/mg macromolecules3

AFB1-DNA 6.8 ± 28a 4.7 ± 2.9b30.9

AFB1-RNA 21.6 ± 0.3a14.3 ± 0.5b33.8

AFB1-Protein 1.2 ± 0.1a 1.2 ± 0.1a0

1 Values are mean ± SEM, n = 5.

2 Diet contained 0.4% L-carnitine (w/w) and given to animals for 6 weeks.

3 Different letters indicate significant difference between groups (p <0.05).

(Source: Sachan & Ayub 1992)

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Protein

Weanling rats fed a low protein diet (5% casein) had fewer AFB1-induced preneoplastic foci in their livers than rats fed a high protein diet (20% casein) (Youngman & Campbell, 1992). The enhanced development of the preneoplastic foci (g-glutamyl transpeptidase-positive foci) by the high protein diet was reversed when the animals were put on a low protein diet. Thus, it was concluded that the low protein diet prevented lesions caused by AFB1.

Mandell et al., (1992) reported that AFB1-induced hepatocar-cinogenicity can occur in both low-and high-protein fed weanling animals. Moreover, the low protein diet (5% lactalbumin) also caused severe liver histopathological changes or sub-acute toxicity symptoms such as necrosis and bile duct proliferation due to AFB1. Also, the protein-deficient animals had a more rapid decrease in glutathione S-transferase activity than the protein-sufficient (20% lactalbumin) animals. High protein fed animals did not show the sub-acute toxicity responses induced by AFB1. Therefore, the authors suggested that protein deficiency is more likely to enhance, rather than protect the liver against, AFB1 toxicity and carcinogenicity.

Fat and Essential Oils

Different types and amounts of fat may have different effects on the carcinogenesis of AFB1. High polyunsaturated oil (corn oil) increased the incidence of liver cancer in rats caused by AFB1 as compared to rats fed with saturated oil (beef fat). The cancer incidence was higher when the corn oil was fed with or after the exposure to AFB1 than when the oil was fed before the AFB1 dose. An increase in induction of AFB1 activation by corn oil was suggested for the high cancer incidence (Newberne, Weiger & Kula, 1979). However, in a similar study, dietary saturated (coconut oil) and unsaturated (corn oil) fats were found to have no significant effect on the adduct formation and the production of AFB1-epoxide in rat livers (Marzuki & Norred, 1984).

In another report, the metabolism and mutagenicity of AFB1 were not significantly different between mice fed with beef fat and olive oil diets (Brennan-Craddock et al, 1990). With respect to the levels of dietary fat, a low-fat (high carbohydrate) diet increased the AFB1-DNA binding more than a high fat diet (Nyathi et al., 1993). The protective effect of a high fat diet may be due to a decrease in the uptake of AFB1 into hepatocytes or a reduction of AFB1-epoxide production. Hashim et al. (1994) investigated the capability of essential oils extracted from nutmeg, ginger, cardamom, celery, xanthoxylum, coriander, cumin, and black pepper to inhibit AFB1-DNA adducts formation mediated by liver microsomal enzymes. All the essential oils tested were suppressive to the adducts formation, and the inhibition was dose-dependent. The modulating effect of these oils was through their ability to inhibit the activation of AFB1.

Trace Elements

Copper inhibited AFB1-DNA binding in vitro (Bhattacharya et al., 1984). A deficiency and an excess of selenium decreased the adduct formation in rats. In chicks, however, excess of selenium did not change the concentration of adducts formed (Chen et al., 1982). Recently,

Dietary factors and aflatoxin B, carcinogenecity

selenium was demonstrated to have no effect on DNA adduct formation in ovary cells and did not effect AFB1 mutagenesis (Shi, How & Ong, 1995).

Copper, manganese, zinc, and selenium were effective in preventing in vitro AFB1-induced mutagenesis. Copper was the most potent among the elements tested. To a lesser extent, iodine, molybdenum, cobalt, and iron were antimutagenic. The investigators suggested that the inhibition was due to interaction of trace elements with the microsomal enzymes (Francis, Shetty & Bhattacharya, 1988).

Feed Restriction

The potentially protective effects of caloric restriction on cancer-causing compounds has promoted considerable interest and investigation. It has been reported that rats fed with 60% of the food consumed by ad libitum animals had lower AFB1 microsomal activation, lower AFB1-adducts, faster plasma clearance, and increased urinary excretion of AFB1 than the ad libitum fed animals. The authors concluded that 40% feed restriction may decrease AFB1 carcinogenicity (Pegram, Allaben & Chow, 1989).

Similarly, about more than 50% reduction in AFB1-DNA binding was found when rats were fed 40% caloric restricted diet (Gao & Chou, 1992; Chou et al., 1997). The restriction also decreased the hepatic DNA double strand damage induced by AFB1. Induction in glutathione S-transferase activity in feed restriction will enhance AFB1-epoxide conjugation to GSH and thus reduce AFB1-DNA adducts formation (Chen et al, 1995).

Cruciferous Vegetables

Cruciferous vegetables have been shown to enhance detoxification of xenobiotics by inducing xenobiotic-metabolizing enzymes in animals and humans (Salbe & Bjeldanes, 1989). High consumption of vegetables such as broccoli, cabbage, cauliflower, and Brussels sprouts has been related to a reduced risk of bladder, colon, and rectum cancers (Grahams, 1983).

Brussels sprouts significantly decreased AFB1-DNA binding and increased the GST activity in rats. Indole-3-carbinol, a compound found in cruciferous vegetables, did not have much effect on the DNA binding and GST activity (Salbe & Bjeldanes, 1989). The same investigators also found that the route of administration, intragastric or intraperitoneal, did not have a different effect on AFB1-DNA binding. Thus, they concluded that the small intestine did not play an important role in AFB1 metabolism. However, in another study that utilized trout, 1000 and 2000 ppm of indole-3-carbinol were shown to strongly depress AFB1-DNA adducts formation (Dashwood et al, 1989). R-goitrin, another compound found in cruciferous vegetables, also exhibited anticarcinogenic properties such as inhibition of AFB1-DNA binding, induction of GST activity, and enhancement of biliary excretion of AFB1 in rats (Chang & Bjeldanes, 1987). Plant Flavonoids and Phenolic Compounds

Five major derivatives of plant flavonoids, namely flavone, flavonol, isoflavone, and flavanol, have been tested on activation of AFB1 and AFB1-DNA adducts formation (Bhattacharya &

Ayuh MY & Sachan DS

Firozi, 1988). Most of the flavonold derivatives significantly inhibited adduct formation, and flavonols being the most potent. Flavonols also showed greater inhibition of AFB1 mutagenicity in bacterial system (Goeger et al, 1988).

Phenolic compounds may have protective effects against AFB1-induced mutagenicity. Gallic acid, chlorogenic acid, caffeic acid, dopamine, p-hydroxybenzoic acid, and salicyclic acid decreased mutation caused by AFB1 in bacterial system containing rat-liver microsomes. The inhibition occurred when the compounds and AFB1 were administered concurrently (San & Chan, 1987). Using the S9 liver fraction that contains the metabolic enzymes, ellagic acid (a compound found in strawberries, grapes, and walnuts) has been shown to be antimutagenic against AFB1 in bacterial assay (Loarca-Pina et al., 1996). The inhibition was greatest when the acid was incubated together with AFB1.

Curcumin, a phenolic compound extracted from tumeric, was recently reported to inhibit the production of AFB1-epoxide by affecting CYP450 enzyme function (Firozi, Aboobaker, Bhatacharya, 1996). The inhibition became higher as the curcumin concentration was increased in the incubation mixture. However, the suppression was reversed when the CYP level in the mixture was higher.

Diterpenes cafestol and kahweol extracted from coffee were shown to inhibit AFB1-DNA covalent binding in rat liver fractions. The decrease in activation of AFB1 and induction of GST expression were the suggested mechanisms of the inhibition (Cavin et al., 1998). Green tea drink fed to rats also inhibit AFB1-DNA binding by affecting AFB1 metabolism (Guozhong et al., 1997).

AFB1 and Food Additives/Drugs Interactions

Food Additives

Rats fed a butylated hydroxyanisole (BHA)-containing diet had lower AFB1-DNA binding, higher GST activity, and higher biliary excretion of AFB1 (Chang & Bjeldanes, 1987). Animals treated with butylated hydroxytoluene (BHT) before or together with AFB1 had lower cancer incidences than the animals administered AFB1 alone (Dragon and Pitot, 1994). However, in trout, BHA did not effect liver tumor incidence, AFB1-DNA binding, or AFB1-glutathione conjugation (Goeger et al., 1988). In vitro system, both BHA and BHT inhibited AFB1-DNA binding (Bhattacharya et al., 1984). Another antioxidant, ethoxyquin, also suppressed AFB1 carcinogenesis by inducing the activity of glutathione S-transferase activity (Kensler et al., 1986).

Drugs

The activities of CYP, GST, and UDPGT enzymes can be induced by several drugs or xenobiotics. Enzyme inducing drugs such as pheno-barbital (anti-seizure drug) and Aroclor 1254, given before or together with AFB1, reduced the number of neoplasms as compared to animals given AFB1 only (Dragan and Pitot, 1994). Although phenobarbital enhanced AFB1 activation, it also induced GST activity and thus increased AFB1-glutathione conjugation.

Dietary factors and aflatoxin B, carcinogenecity

Therefore, the overall hepatic binding of AFB1 to DNA is reduced (Loury, Hseih & Brard, 1984; Lotlikar et al, 1989). Other inducers such as ethoxyquin (Kensler et al., 1986), and oltipraz (Primiano et al., 1995), have also been shown to inhibit AFB1-induced carcinogenesis by inducing GST activity. In a study employing human hepatocytes, oltipraz was also reported to lower the production of AFB1-epoxide by inhibiting the CYP1A2 and CYP3A4 activities (Longouet et al., 1995).

A compound isolated from a Chinese herb, dimethyl-4,4’ dimethoxy-5,6,5’,6’-dimethylenedioxy biphenyl-2,2’-dicarboxylate (DDB), is a drug used for its liver protective effects. Pretreatment of rats with DD

B inhibited liver damage caused by AFB1. DDB also induced the activity of glutathione S-transferase and therefore enhanced detoxification of AFB1-epoxide (Liu et al., 1995). Crocetin, a carotenoid isolated from the seeds of Cape jasmine, has been reported to elevate the cytosolic glutathione S-transferase activity and glutathione concentration in a fibroblast cell line treated with AFB1 (Wang, Shiah & Lin, 1991a). Another Chinese herbal drug, geniposide, isolated from a fruit of a species of gardenia, can also inhibit AFB1-induced DNA binding. Induction of glutathione S-transferase and gamma glutamyl cysteine synthase (involved in glutathione synthesis) activities, and suppression of AFB1-induced unscheduled DNA synthesis were the suggested mechanisms of action of geniposide (Wang, Wang & Lin, 1991b; Wang, Lai & Wang, 1992).

Cortisol pretreatment in rats markedly increases the acute hepatoxicity of AFB1 (Chentanez et al., 1988). The toxicity effects, such as higher mortality rates, increased in liver triacylglycerol, and elevated AFB1 binding to DNA and protein, were dose-dependent. These cortisol effects may by due to increased metabolism of AFB1 to its epoxide derivative.

Ethanol, when given to animals together with or prior to aflatoxin, increased the aflatoxin hepatotoxicity and DNA binding (Toskulkoa & Glinsukon, 1986; Toskulkoa, Lohokachonpan & Glinsukon, 1991; Sahaphong,Toskulkoa & Glinsukon, 1992). The alcohol pretreatment increased the activation of AFB1 but not the GST activity. This explains the increased binding of AFB1 to DNA. On the other hand, when given after AFB1 administration, ethanol showed no influence on AFB1-DNA binding (Messlbeck Campbell & Roe, 1984).

CONCLUSION

Aflatoxins are a real public health problem and research should be continued to prevent their presence in food, and to inhibit their harmful effects. Much progress has been achieved in showing the importance of dietary factors in modulation of AFB1 toxicity and carcinogenicity. Obviously, there are still a wide range of dietary components that can be explored and investigated. Additionally, the more important research areas would be in explaining the protective mechanisms and formulating the effective “dose” before any true public health measures could be recommended.

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环境影响因素评价方法

环境影响因素评价方法 多因子评分法该方法对能源、资源、固废、废水、噪声等五个方面异常、紧急状况制定评分标准。制定评分标准应尽量使每一项环境影响的量化(如以下环境因素评分表),采用评价表各因子重要性参数(A,B,C,D,E值)来计算重要性总值(R),确定重要性指标(S),根据重要性指标可划分1级,2级,3级三个等级,得到环境因素控制分级,从而确定重要环境因素。 (1)多因子评分表 ①能源、资源耗用评分表 因子因子分类评分总分(R)/重要性判定 A:回收性可循环利用1 R=A*B*C当R=20分或大于时,则评定为重要环境因素。 不可循环利用 2 B:贫乏性不贫乏1 未来可能贫乏 2 已贫乏 3 C:使用量小于10公斤/月1 10-100公斤/月2 101-500公斤/月3 501-1000公斤/月4 大于1000公斤/月 5 ②固体、液体废物评分表 因子因子分类评分总分(R)/重要性判定 A:产生量(对固废、液体废弃物) 小于50公斤/月1 R=A*B*C*D*E当 24≤R<32,S=1级;当32≤R<48,S=2级;当48≤R,S=3级51-200公斤/月2 201-500公斤/月3 501-1000公斤/月4 大于1000公斤/月 5 A:产生量(对废水) 小于1吨/月1 1- 10吨/月2 11-100吨/月3 101-500吨/月4 大于500吨/月5 B:回收性可回收再利用1 不可回收再利用 2 C:降解性可生物降解1 不可生物降解 2 D:危害性对人或环境无伤害或影响1

对人或环境有影响但不造成伤害 2 对人或环境有影响并伤害较大 3 对人或环境有立即或长期伤害 4 E:燃烧性(适用于固体液体废物) 适燃或燃烧时不会产生危害物质1 不适燃或燃烧时会产生危害物质 2 ③气体排放 因子因子分类评分总分(R)/重要性指标(S) A;持续时间(累计排放时间)小于1小时/天1 R=A*B*C当16≤R<24,S=1;当24≤R<32,S=2;当32≤R,S=3; 1- 5小时/天2 5-10小时/天3 大于10小时/天 4 B:严重性(危害性)对人或环境无伤害或影响1 对人或环境有影响但不致伤害 2 对人或环境有影响且有伤害 3 对人或环境有立即或长期伤害 4 C:影响范围作业场所受影响1 厂区内受影响 2 对厂区外有害影响 3 ④噪声 因子因子分类评分总分(R)/重要性指标(S) A:周界噪声值昼间≤65dB(A)夜间≤55dB(A) 1 R=2时定为重要环境因素 R=A*B当R=8,S=1;当9≤R<12, S=2;当12≤R,S=3; 昼间>65db(A)夜间>55db(A) 2 A:现场噪声值小于85dB(A) 1 85-90dB(A) 2 大于90dB(A) 3 B:员工暴露时间小于1小时/天1 1- 4小时/天2 4-8小时/天3 大于8小时/天 4 ⑤异常、紧急状况固体、液体废物排放 因子因子分类评分总分(分)/重要性指标(S) A:发生概率发生几率小,几乎不发生1 R=A*B*C*D*E*F当24≤R<32,S=1;当32≤R<48,S=2;当48≤R,S=3; 每年发生一次 2 每季度发生一次 3 每月发生一次 4

影响公众评价的因素

影响公众评价的因素 每一个组织都是环境的产物,而公众又是环境的主体,组织在与公众不断相互积极作用过程中得以生存和发展,这一过程中影响公众对组织评价的因素有很多,主要表现在以下四个方面: 一、组织形象: 组织自身的形象是影响公众评价的决定性要素,而公众对组织自身形象的评价主要包括:①公众对组织机构及其效益的评价和看法。组织机构的设置、运转、办事效率等情况,会给公众留下深刻印象,是形成组织形象的重要因素;②公众对组织的管理水平的评价和看法。管理水平高低代表组织在社会中的地位,高水准的管理是组织求得公众信任、建立良好组织形象的重要前提;③公众对组织人员素质的评价和看法。组织人员的素质包括组织决策层及各部门人员的工作能力、知识结构、道德品质和心理素质等,是组织生存和发展的重要主体条件,是形成组织形象的重要因素;④公众对服务质量的评价。公众对组织形象的评价主要源于其直接感受,服务质量是形成组织形象的最直接因素。组织要建立和维护良好形象,必须通过调查研究确定组织的实际社会形象,之后采取公共关系措施,设计并实施具体的公共关系活动计划,调整、修改或重塑组织形象。 二、传播媒介及活动: 是否采取措施向公众宣传组织自身,以及采用何种传播媒介和传播方式宣传组织自身,组织应结合自身的情况,采用适合组织本身且快速有效的传播媒介和方式让公众了解组织情况,塑造高美誉度的组

织形象,不能闭门造车,但也不能虚假宣传,误导公众。 三、社会环境: 社会环境包含的内容很多,涉及到文化、社会道德、法律、经济、科技、教育等等范畴,这里影响公众对组织的评价着重指的是文化、社会道德、法律、经济环境。首先,不同地区都有自己的区域文化,不同种族的人也有自己的种族文化,组织的发展必须适应组织发展区域不同文化所创造的环境,充分的尊重文化差异;其次,组织的行为是否符合社会公共道德又是影响公众对组织评价的关键因素,组织主动承担社会责任,保护环境,投身慈善,有利于公众提高对组织的评价和认可度;然后,法律是公众评价组织的基本准绳,如果组织违法犯罪,危害社会,必然会受到公众的谴责,此外还要受到法律地制裁;最后,整个经济环境指引了组织发展的方向,如果组织违背经济发展的必然规律,浪费社会资源,必然会遭到公众的抛弃,被社会淘汰。 四、公众自身: 这里所指的公众是广义上的一般的公众群体,不局限于某一特定的人群,来自不同类别的公众,因此影响公众对组织的评价还取决于公众本身,主要表现为公众的性别、年龄、科学文化素养、社会阅历以及公众对组织了解程度和组织活动的参与度。 综上所述,以上四个方面是影响公众对组织评价的主要因素,因此,组织必须这四个方面着手,赢得公众对组织的积极评价,实现组织自身的生存与发展。

评估因素介绍

评估因素介绍

一、公司等级评估因素 1、员工数量 主要反映为组织工作的员工数量,其中包括非正式员工。 2、可控资产 主要反映组织可以实际控制和支配的资产。对组织可控资产的定义主要包括以下3部分:公司的固定资产、组织从银行等外部金融机构获得的贷款、通过股权控制其它子公司,则其子公司的资产也应该计算为该组织的可控资产。 3、可控资产 主要反映组织的业务所涉及的广义行业数量。根据对行业划分的标准,广义行业包括金融行业、房地产行业、高科技行业、快速消费品行业、医药行业等,而诸如证券、基金、保险等均算作金融行业的细分行业领域。 ?单个行业:指组织的业务范围控制在一个广义行业的范畴内; ?多个行业:指组织的业务范围包括2-4个广义行业范畴,且各行业范畴间有一定的业务往来; ?多行业集团(多于5个行业):指组织的业务范围拓展到5个以上的广义行业范畴,且各行业范畴间并没有明显的业务往来。 4、办公地点的地域分布 主要反映组织日常业务所能够覆盖到的地域范围。在此项因素的界定过程中,我们只考查组织的业务覆盖面,淡化组织在各地业务机构的发展规模,以及各地业务人员素质、职位等级与所属的职能序列。 ?本地:指组织的业务只覆盖公司所在的一个城市或地区; ?全国:指组织的业务范围超越所在城市、地区的概念,在全国其它城市、地区也设有业务机构; ?跨国:指组织的业务范围超越中华人民共和国范围,在其它国家(七个国家以下)也同时设有业务机构; ?全球(七个国家、地区以上):指组织在全球范围内开展相关业务,且在各国设立的业务机构均达到一定规模。 二、评定岗位所隶属的层级的因素 用于评定岗位所隶属的层级的因素包括影响、沟通和创新。

跨区域科技协同创新的影响因素分析

跨区域科技协同创新的影响因素分析

跨区域科技协同创新的影响因素分析

摘要:跨区域科技协同创新是区域间整合科技资源、带动区域科技及经济社会协调发展的重要模式及战略选择,深入分析其影响因素有助于更好地促进区域间科技合作与融合,并带动区域整体的发展。跨区域科技协同创新的影响因素主要包括三个方面:绩效因素、内部因素和外部因素。其中,绩效因素是协同创新的结果也是重要行为导向;内部因素是和主体行为相关的因素;外部因素指影响创新主体行为的资源、环境、链接等相关因素。 关键词:跨区域;科技协同创新;创新绩效;创新意愿和能力 doi: 10-13939/j-cnki-zgsc-2016-26-065 一、引言 跨区域科技协同创新,是指不同区域的科技创新主体(包括企业、高校、研究机构、政府、科技中介)跨越行政区划的限制,与其他创新主体协作开展科学研究、技术开发、技术应用和转化等科技

创新活动,共同调动、整合区域间的科技资源,通过复杂的非线性相互作用而产生单独个体和单个区域无法实现的整体协同效应和创新绩效。通过跨区域科技协同创新,能够促进区域间创新系统有效整合,带动各个区域的科技、经济、社会、环境等的全面可持续发展。 跨区域科技协同创新的实质是在一定的创新绩效导向下,创新主体具有一定的创新需求和创新能力的前提下,在外部环境、资源基础和链接条件等的共同作用下所开展的创新活动。因此,可以说跨区域科技协同创新的影响因素主要是绩效因素、内部因素和外部因素。其中,协同创新绩效是跨区域科技协同创新的结果,是跨区域科技协同创新的结果要素。内部因素指和主体行为相关的因素,主要是创新主体的协同创新意愿和能力,内因直接影响跨区域科技协同创新绩效;外因主要指影响创新主体行为的相关因素,包括环境因素、链接

企业创新力不足影响因素.

企业创新力不足影响因素 摘要:创新力是企业保持竞争优势的核心要素,企业必须加强创新能力的培养。总结我国企业创新力不足,分析相关影响因素。关键词:企业创新力;影响因素;分析改革开放以后,特别加入世界贸易组织后,我国的企业飞速发展,目前初步具备成为自主创新的主体条件和动力。但是,在激烈的内外竞争环境下,我国企业又直面前所未有的风险与机遇。与有竞争力的国际大企业相比较,我国的企业,特别在以培养核心竞争力为主的企业创新还普遍存在着巨大的差距和劣势。一、我国企业创新能力的现状为了摆脱在低端市场的微利窘境,提高企业的市场竞争能力和抗风险能力,我国多数企业已经意识到培养自主创新能力的重要性,它们都纷纷完善制度,立足于全国甚至全球范围内展开创新竞赛。经过多年的积累与实践,我国的一些企业已逐步形成和发展了自己的核心技术,并使我国多项技术水平居世界前沿。2005年,国家科技进步奖开发项目中,企业参与完成的项目占72.5%,其中企业独立完成项目占21.1%,企业与高校、科研院所合作完成项目占51.4%。近年来,电子信息产品出口额占到全国外贸出口总额的20%以上,软件及信息服务业得到较快发展,其市场销售额达560亿元。数字化产品以及信息家电等新一代产品正在快速发展。计算机、移动通信、软件、集成电路、网络产品、数字化终端产品成为新的发展热点。 20世纪90年代以来,我国科技投入不断增加,2001年全国研究与开发R&D投入为977.9亿元,占国内生产总值的1.0%以上。而在1990年,这两个数字分别是125.34亿元和0.68%。20世纪90年代后,我国受高等教育的人数猛增,高科技人才辈出,2001年我国科技人员增致136.8万人。2004年,中国企业向世界知识产权组织(简称WIPO)递交专利权申请增到1,782件,比前一年增长38%,17。总体上看,我国企业创新取得了长足进步,有些接近世界先进水平。但是,最新公布的经济普查公报显示,2004年我国规模以上企业仅有11.9%开展科技活动,大中型企业开展科技活动的只有38.4%,大中型企业研发经费支出只占其销售收入的 0.71%,我国企业研发经费人均支出仅为美国的1.2%,日本的1.1%。到2003年底,我国大中型企业71%没有自己的研发机构,2/3的企业没有自己的技术开发活动,使我国企业的新技术与新产品开发能力薄弱,决大多数企业只能从事技术含量低、附加值底的产品生产,大量的科技人才集中与科研院所和大学校园内,由于工资与激励的扭曲,科技人员把主要精力集中于评职称、发论文和获奖励等方面,而不是专注于研究发明,即使他们从事研发工作,也主要在基础理论研究,而与企业和市场严重脱节。由此而知,我国企业的创新的能力有待于进一步加强。二、我国企业创新力不强的主要原因 (一)企业的R&D投入不足虽然,企业研发费用逐年增加,但我国企业尤其是国有企业长期受计划经济的影响,还没有完全成为R&D投资主体,有些企业过分迷信外国产品和技术,以购买替代创新。企业为实现发展壮大,主要通过外延扩大再生产,没有采用新技术和开发新产品创新方式。国际企业界普遍认为,研发费用达到销售收入的5%以上,企业才有竞争力,占2%仅够维持,不足1%的企业难以生存。1997年IBM公司的研究开发费用支出高达48.68亿美元,占总营业额的6.2%。而相应的国内电子产品企业在R&D方面的平均投入不到销售额的1%,二者研发投入差距相差太大。我国企业研发经费不足已成公认事实,没有足够的资金,难以支持企业的创新力取得大的发展。

影响创新成功的因素

影响创新成功的因素 创新是一个复杂、牵涉组织方方面面的活动。它需要一整套相互呼应的实践方法和流程来架构、设计和激励。那么,影响创新成功的因素有哪些呢? 精心为大家搜集整理了影响创新成功的因素,大家一起来看看吧。 影响创新成功的因素1:领军人物创新想要成功,它涉及到很多因素,首先就是人才,通过许多案例我们可以看出,没有像田中更一、王选等这样领军型的科学家的作用,汉字激光照排系统等创新是不可能取得成功的,所以说人才是第一要素,创新的关键在人才。 影响创新成功的因素2:创新团队创新他需要把多方面的知识结合起来去实现某一个目标去解决某一个问题,它需要团队作业,也就是将一个团队的知识背景合成在一起,进行跨学科、跨领域的攻关,这样才能够取得成功,以领军人才为中心形成一个紧密合作型的公关团队,进行互相交流、互相促进,才能取得创新成功。所以团队非常重要。 影响创新成功的因素3:知识储备除了领军人物、创新团队,想要取得创新成功还要有一个条件,那就是需要知识储备这个条件,我们应该有很庞大的科技文献的收藏机构,不仅是单纯的搜寻,还要把这些东西用很简短的语言把它提炼出来,让各个企业参考利用,更方便科研人员的利用。所以没有一定的知识平台,想要完成创新也是很

难的。 影响创新成功的因素4:工业技术因为如果我们很多工业基础技术跟不上来,我们要的一般原器件没有,它需要进口,而且进口的渠道往往还不畅看,就是说一个买不来,第二个就是买得来它很折腾人,如果我们国内能够生产的话,显然我们的创新就要容易得多,所以提升创新能力,我们可以看到,其实整个一个国际的工业技术基础非常重要。 影响创新成功的因素5:创新体制创新需要一个好的保护体制,有了这样的专利保护,那么我们才能使创新取得成功,创新能够获益,就是那个制度非常重要。今天我们在制度设计中间需要考虑很多原因,很多因素,其中包括专利法恐怕还是需要重新审视它的价值。 影响创新成功的因素6:科学仪器科学仪器设备也非常重要,这一点我们感慨是非常深刻的,因为巧妇难为无米之炊,没有一个好的科学仪器设备,一般来讲解决重大发现,解决一些创新,想要有大的突破,有大的创新,其实是比较困难的。 影响创新成功的因素7:创新文化第一,崇尚创新的文化。文化环境对一个国家,一个企业对于创新的影响是巨大的。第二,追求卓越。所以一个创新的文化,一个追求卓越的文化的形成非常的重要,还有宽容失败。第三,团结协作。团结协作的这种文化氛围非常重要,只有这样他才能够更容易取得成功。 影响创新成功的因素8:人才培养一个创新想要获得成功的话,我们的着力点有很多,但是在所有的这一切中间,最关键的还是人,

资产质量的影响因素和综合评价研究

资产质量的影响因素和综合评价研究 资产是保证企业正常运转的一个非常重要的因素,资产质量从表面来看就是资产在利用过程中所表现出来的一种质量。目前来说大部分国内外学者研究的是信贷资产质量,对于企业资产质量研究很少,而且研究也不是很成熟,研究方法比较单一,研究面还较窄。但是现在很多投资者和企业管理者越来越重视资产质量的管理,企业资产质量不高就是企业发展道路上的一个障碍,它导致企业盈利能力低下,资源得不到充分利用,造成资源浪费。企业资产质量不好,不仅限制企业自身的发展,也危害我们国家才兴起几十年的市场经济,因此,如何正确定位影响企业资产质量的因素,如何评价企业资产质量,如何帮助企业通过资产管理提升资产质量是一个迫切需要研究的课题,而且这个研究具有重要的意义。 本研究以会计学和财务管理学等财务学科为理论基础,在国内外学者研究的基础上,以我国上市公司资产质量研究为主线,先进行规范研究在做实证研究。本研究的研究思路是,先对国内外研究资产质量的文献进行归纳综述,再阐述与本研究相关的理论,进而对资产质量的概念进行界定,归纳出企业资产质量的特征,通过分析资产质量对企业的相关影响,总结出四个主要因素,在这个前提上建立综合评价体系,通过实证研究得到资产质量综合评价函数,证实相关因素对资产质量的影响,也找出我国上市公司资产质量管理中存在的一些问题。本研究是从影响资产质量的四个因素:资产质量的有效性,资产质量的存在性,资产质量的收益性和资产质量的安全性出发,选用了相关财务指标数据,在SPSS17.0中文版中进行主成分分析,以我国制造业A股上市公2008年至2011年的年报数据为研究样本,对资产质量进行量化,在软件中得到评分函数,对选用公司资产质量进行排名。实证结果发现,主成份分析资产质量,因行业性质不一样产生的效果也不一样,有些行业不适合这种方法分析资产质量。 实证结果也发现有些上市公司在资产质量管理中存在一些问题,本研究针对上市公司资产质量现状提出了一些对策,希望通过本研究可以对企业如何管理资产质量和企业分析公司资产质量提供一个方法。

考核的影响因素与关键因素

考核的影响因素与关键因素 影响因素 影响绩效的主要因素有员工技能、外部环境、内部条件以及激励效应。 员工技能是指员工具备的核心能力,是内在的因素,经过培训和开发是可以提高的;外部环境是指组织 和个人面临的不为组织所左右的因素,是客观因素,我们是完全不能控制的;内部条件是指组织和个人开展工作所需的各种资源,也是客观因素,在一定程度上我们能改变内部条件的制约;激励效应是指组织和个人为达成目标而工作的主动性、积极性,激励效应是主观因素。 在影响绩效的四个因素中,只有激励效应是最具有主动性、能动性的因素,人的主动性积极性提高了,组织和员工会尽力争取内部资源的支持,同时组织和员工技能水平将会逐渐得到提高。因此绩效管理就是通过适当的激励机制激发人的主动性、积极性,激发组织和员工争取内部条件的改善,提升技能水平进而提升个人和组织绩效。

关键因素 主要有以下五个方面: ①工作者本身的态度、工作技能、掌握的知识、IQ、EQ 等等; ②工作本身的目标、计划、资源需求、过程控制等; ③包括流程、协调、组织内部的工作方法; ④工作环境,包括文化氛围、自然环境以及工作环境; ⑤管理机制,包括计划、组织、指挥、监督、控制、激励、反馈等。 其中每一个具体因素和细节都可能对绩效产生很大的影响。控制了这些因素就等于也同时控制了绩效。管理者的管理目标实质上也就是这些影响绩效的因素。 绩效评估的是结果的好坏,绩效管理需要探求产生结果

的原因,逆向追踪绩效因素。根据对结果的影响作用,不同的因素有不同的影响力。当其它因素都很稳定时,管理者需要关注于某一个特定的因素,因为这个因素的变化会对绩效产生直接的重大影响。哪些因素容易变化,对绩效的影响作用大,管理者就需要关注和考核哪些因素。 但要注意的是,过分注重绩效会使员工也只关注绩效而不关注其他东西,这样的坏处是短期内公司会得到大利益但不利于可持续发展,要有大教堂思维的人才能做成大事。

科技创新的影响因素

提高国家科技创新能力的影响因素1602302 邬鹏飞 早在上世纪80年代,邓小平同志就精辟的指出:“科学技术是第一生产力”,科学技术的进步将极大提高国家的综合国力。进入 21世纪以来,科技创新已成为国际竞争中成败的主导因素,科技竞争的能力将决定一个国家在未来世界竞争格局中的命 运和前途,成为维护国家安全、增进民族凝聚力的关键所在。建设国家创新体系,促进科技创新,成为世界各国关心的重要问题。虽然我国是经济和人口大国,但是科技发展与创新的水平还不够高、能力还不能完全满足我国经济又好又快发展的需求,科技创新能力不足成为制约我国经济发展的因素之一。如何通过提高国家科研创新能力,推动国家的科技进步以及经济发展,这是我们必须认真思考与研究的问题。个人觉得可以从以下几个方面着手: 一、统筹兼顾,实施有力的国家促进战略是提高科技创新能力的首要前提 科学可行的战略筹划,是完成一件事首要前提,实施科学的国家促进战略,认真谋划,开拓进取,调动全国各方面资源,为科技创新指引方向、保驾护航。

要立足当前,着眼长远,按照科研事业的一般规律,制定成体系、相配套的一系列国家促进政策。鼓励科研主体积极开展科研创新活动,不仅从实验室、经费等硬件条件上保障科研人员和科研单科学的科研创新还要构建适当宽松的科研环境、位开展科研活动, 评价体系等,完善科研创新软件条件。要大力宣传科研创新事迹,树立科技创新典型,增强科研主题的责任感、使命感和荣誉感,在全社会营造一种创新的风尚,把科技创新当作一颗种子深深植入我国文化的厚土中。 二、着眼全局,构建完善的人才培养体系是提高科研创新能力的根本保证 人力资源是推进科技创新的核心要素, 实施人才战略, 激发人才的积极性创造性是推动科技创新的一项重要内容。 要秉持科技是第一生产力、人才是第一资源的理念,兼收并蓄,吸取国际先进经验,推进教育改革,提高教育质量,培养更多、更高素质的人才,同时为各类人才发挥作用、施展才华提供更加广阔的天地。 三、注重质量,创立高效的成果转化机制是提高科研创新能力的重要手段 科技成果转化是落实“科学技术是第一生产力”的关键。发展经济要依靠科技进步,发挥第一生产力的作用,而只有把作为第一生产力重要体现的科技成果在生产实践中得到广

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