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Biomedical subjects

Min Cao

Publications and source records attributed to Min Cao.

31 records · Page 2Linked to original sources
PubMed2004

[A prospective cohort study on the comparison of risk of occupational dust exposure and smoking to death].

OBJECTIVE: To compare the effects of dust exposure and smoking on mortality. METHODS: Based on the Guangzhou Occupational Health Surveillance Record System established in 1989-1992, 80 987 factory workers, aged > or = 30, occupationally exposed to dust and non-exposure to dust, were included in a prospective cohort study. RESULTS: (1) The mean age of the cohort was 43.5. Most subjects were workers, with secondary education, and married. Out of them 16.3% having ever exposed to dust, 43.7% ever smoked and 33.5% drank alcohol. (2) The cohort were traced for 8 years on average, but 35 were lost for follow-up. Malignant neoplasm was most commonly seen among 1539 deaths. (3) The adjusted relative risk (RRs) of death of all causes, malignant neoplasm and cerebro-cardiovascular diseases for dust exposed workers were close to those for smokers. However, the adjusted RRs of death of nasopharynx cancer and respiratory system diseases for dust exposed workers were higher than those for smokers. The adjusted RRs of death of lung cancer and stomach cancer for smokers were 2.2 times and 1.5 times of that for dust exposed workers respectively. Dust exposure combined with smoking caused significantly higher death RR. (4) In males, the adjusted RRs of death of all causes, malignant neoplasm and respiratory system diseases for silica dust exposed workers and the adjusted RR of death of cerebro-cardiovascular diseases for wood dust exposed workers were higher those in smokers. (5) The population attributable risk percentage (PARP) of all causes of death for smokers was 2.5 times of that for dust exposed workers. (6) In males, the risks of death for all causes, malignant neoplasm, lung cancer and stomach cancer increased with the amount of smoking per day and the duration of smoking. The risks of death caused by coronary heart disease and respiratory system diseases were increasing with the amount of smoking per day and the duration of smoking respectively. CONCLUSIONS: The adjusted RRs for dust exposed workers were close to those for smokers with dust exposure and smoking having synergistic effects. Some of the adjusted RRs for smokers were higher than those for dust exposed workers PARP for smokers was higher than that for dust exposed workers. Our findings suggested that there was a significant dose-effect between smoking and risk of deaths.

Adult↗
PubMed2003

Mycorrhiza of plants in different vegetation types in tropical ecosystems of Xishuangbanna, southwest China.

We examined plants growing in four tropical vegetation types (primary forest, secondary forest, limestone forest and a slash and burn field) in Xishuangbanna, southwest China for mycorrhizal associations. Of the 103 plant species examined (belonging to 47 families), 81 had arbuscular mycorrhizal (AM) associations, while three species possessed orchid mycorrhiza. AM colonization levels ranged between 6% and 91% and spore numbers ranged between 1.36 spores and 25.71 spores per 10 g soil. Mean AM colonization level was higher in primary and secondary forest species than in plant species from limestone forests and a slash and burn field. In contrast, mean AM fungal spore numbers of the primary and limestone forest were lower than in the secondary forest or the slash and burn field. AM fungal spores belonging to Glomus and Acaulospora were the most frequent in soils of Xishuangbanna. AM fungal colonization and spore numbers were significantly correlated to each other and were significantly influenced by vegetation type.

China↗
PubMed2003

Two MerR homologues that affect copper induction of the Bacillus subtilis copZA operon.

Copper ions induce expression of the Bacillus subtilis copZA operon encoding a metallochaperone, CopZ, and a CPx-type ATPase efflux protein, CopA. The copZA promoter region contains an inverted repeat sequence similar to that recognized by the mercury-sensing MerR protein. To investigate the possible involvement of MerR homologues in copZA regulation, null mutations were engineered affecting each of four putative MerR-type regulators: yyaN, yraB, yfmP and yhdQ. Two of these genes affected copper regulation. Mutation of yhdQ (hereafter renamed cueR) dramatically reduced copper induction of copZA, and purified CueR bound with high affinity to the copZA promoter region. These results suggest that CueR is a direct regulator of copZA transcription that mediates copper induction. Surprisingly, a yfmP mutation also reduced copper induction of copZA. Sequence analysis suggested that yfmP was cotranscribed with yfmO, encoding a putative multidrug efflux protein. The yfmPO operon is autoregulated: a yfmP mutation derepressed the yfmP promoter and purified YfmP bound the yfmP promoter region, but not the copZA promoter region. Since the yfmP mutant strain was predicted to express elevated levels of the YfmO efflux pump, it was hypothesized that copper efflux might be responsible for the reduced copZA induction. Consistent with this model, in a yfmP yfmO double mutant copper induction of copZA was normal. The results demonstrate the direct regulation of the B. subtilis copper efflux system by CueR, and indirect regulation by a putative multidrug efflux system.

Amino Acid Sequence↗
PubMed2003

Regulation of the Bacillus subtilis extracytoplasmic function protein sigma(Y) and its target promoters.

The Bacillus subtilis extracytoplasmic function sigma factor sigma(Y) is of unknown function. We demonstrate that the sigY operon is expressed from an autoregulatory promoter site, P(Y). We selected for transposon-induced mutations that upregulate P(Y) transcription in an attempt to identify genes involved in sigma(Y) regulation. The resulting insertions disrupted yxlC, the gene immediately downstream of sigY. However, the phenotype of the yxlC::Tn10 insertion was due to polarity on the downstream genes of the sigY operon; a nonpolar insertion in yxlC did not lead to derepression of P(Y). Further analyses revealed that both yxlD and yxlE encoded proteins important for the negative regulation of sigma(Y) activity. A comparison of the transcriptomes of wild-type and yxlC::Tn10 mutant strains revealed elevated expression of several operons. However, only one additional gene, ybgB, was unambiguously identified as a direct target for sigma(Y). This was supported by analysis of direct targets for sigma(Y) transcription with whole-genome runoff transcription followed by macroarray analysis.

Bacillus subtilis↗
PubMed2003

[Study for acid-base homeostasis in children with growth hormone deficiency].

OBJECTIVE: To study the difference of plasma actual bicarbonate between the children with growth hormone deficiency (GHD) and idopathatic short stature (ISS) and to value the plasma bicarbonate standard deviation scores (SDS) in diagnosis of GHD. METHODS: Forty-seven short stature children were divided into two groups (GHD and ISS) according to the peak GH response to provocative test. Plasma actual bicarbonate concentrations anion gap (AG), base excess and electrolytes were measured in 47 children with short stature before GH provocative tests. RESULTS: The mean plasma actual bicarbonate concentrations, bicarbonate SDS were (22.60+/-1.29)mmol/L and -0.27+/-0.98 respectively in GHD children, which were significantly lower than those of ISS children (P<0.01), whereas AG was higher than that of ISS children [(11.73+/-4.52 vs 7.87+/-1.70) mmol/L], P<0.01. Seventy-two percent of patients with bicarbonate SDS<or=1 s were diagnosed as GHD. CONCLUSION: Plasma actual bicarbonate concentrations and bicarbonate SDS are lower in patients with GHD than those in patients with idopathatic short stature. Evaluation of plasma bicarbonate SDS of short stature children can predict the probability of GHD, especially when bicarbonate SDS is less than 1 s.

Acid-Base Equilibrium↗
PubMed2003

[Regeneration in gaps of the middle-mountain moist evergreen broad-leaved forest of Ailao mountains].

On the basis of investigation on gaps in the middle-mountain moist evergreen broad-leaved forest of Ailao Mountains Natural Reserve, Yunnan Province, tree seedlings (H < or = 50 cm) composition were compared in the gaps and the non-gap stand. The results showed that the dominant tree species of the forest were not preponderated over others in the gaps. The composition of tree seedlings in the gaps differed from those in the non-gap stand. The species diversity of tree seedlings in the gaps(H = 2.73, D = 0.89) were higher than those in the non-gap stand (H = 2.25, D = 0.82), and the Jaccard correlative coefficient were only 0.6. The density of tree seedlings in the gaps (38,636 N.hm-2) was much higher than that in the non-gap stand (17,323 N.hm-2), of which many species were only found in the gaps. The dominant height of the tree seedling in the gaps and the non-gap stand were also 11-20 cm, but the percentage of the tree seedlings higher than 20 cm in the gaps was significantly higher than that in the non-gap stand. The gap sizes had important impact on the tree seedling germination, and different species of tree seedling dominated in different size classes of gap.

Conservation of Natural Resources↗
PubMed2003

[A cohort study on the relationship between blood pressure levels and the mortality of cerebro-cardiovascular diseases in Guangzhou workers].

OBJECTIVE: To study the relative risk (RR) of mortalities of cerebro-cardiovascular diseases (CVD) in Guangzhou workers with hypertension. METHOD: Prospective cohort study was conducted in 78,379 workers, aged >or= 35, from 399 factories. Cox regression model were mainly used for data analysis. RESULTS: (1) There were 48,705 male and 29,674 female workers in the cohort. All workers were followed-up for 8 years. 363 CVD deaths (male 305, female 58) mainly died of stroke, coronary heart disease and hypertension. The crude mortalities were 78.58/100,000 person years in male and 24.55/100,000 person years in female. (2) Compared with the optimal or normal blood pressure (ONBP), the RR (95%) of CVD deaths with high blood pressure (HBP) were 6.19 (4.85 - 7.91) in male and 2.78 (1.59 - 4.85) in female. In male, compared with ONBP, the RR of CVD deaths without illness but with 1st-grade HBP at baseline, and of those suffered non-CVD but with 1st-grade HBP at baseline, and of those suffered CVD with 2nd-grade HBP at baseline were 3.98, 3.25 and 3.15 respectively (P < 0.01). (3) After stratifying of age, smoking, drinking, educational levels and occupational exposure, the RR of CVD deaths was higher in those who were younger, or ever-smoking, non-drinking, higher educational level, exposed to occupational hazards and with hypertension. CONCLUSION: There is relationship between BP levels and CVD mortality. High BP may affect CVD deaths at younger age. Comprehensive measures should be used to reduce the risk of CVD deaths.

Adult↗
PubMed2002

Defining the Bacillus subtilis sigma(W) regulon: a comparative analysis of promoter consensus search, run-off transcription/macroarray analysis (ROMA), and transcriptional profiling approaches.

The Bacillus subtilis extracytoplasmic function (ECF) sigma factor sigma(W) controls a large regulon that is strongly induced by alkali shock. To define the physiological role of sigma(W) we have sought to identify the complete set of genes under sigma(W) control. Previously, we described a promoter consensus search procedure to identify sigma(W) controlled genes. Herein, we introduce a novel method to identify additional target promoters: run-off transcription followed by macroarray analysis (ROMA). We compare the resulting list of targets with those identified in conventional transcriptional profiling studies and using the consensus search approach. While transcriptional profiling identifies genes that are strongly dependent on sigma(W) for in vivo expression, some sigma(W)-dependent promoters are not detected due to the masking effects of other promoter elements, overlapping recognition with other ECF sigma factors, or both. Taken together, the consensus search, ROMA, and transcriptional profiling approaches establish a minimum of 30 promoter sites (controlling approximately 60 genes) as direct targets for activation by sigma(W). Significantly, no single approach identifies more than approximately 80% of the regulon so defined. We therefore suggest that a combination of two or more complementary approaches be employed in studies seeking to achieve maximal coverage when defining bacterial regulons. Our results indicate that sigma(W) controls genes that protect the cell against agents that impair cell wall biosynthesis but fail to reveal any connection to operons likely to function in adaptation to alkaline growth conditions. This is consistent with the observation that a sigW mutant is unaffected in its ability to survive alkali shock. We conclude that in B. subtilis sudden imposition of alkali stress activates the sigma(W) stress response, perhaps by impairing the ability of the cell wall biosynthetic machinery to function.

Bacillus subtilis↗
PubMed2002

Antibiotics that inhibit cell wall biosynthesis induce expression of the Bacillus subtilis sigma(W) and sigma(M) regulons.

Bacillus subtilis encodes seven extracytoplasmic function (ECF) sigma factors. The sigma(W) regulon includes functions involved in detoxification and protection against antimicrobials, whereas sigma(M) is essential for growth at high salt concentrations. We now report that antibiotics that inhibit cell wall biosynthesis induce both sigma(W) and sigma(M) regulons as monitored using DNA microarrays. Induction of selected sigma(W)-dependent genes was confirmed using lacZ reporter fusions and Northern blot analysis. The ability of vancomycin to induce the sigma(W) regulon is dependent on both sigma(W) and the cognate anti-sigma, RsiW, but is independent of the transition state regulator AbrB. These results suggest that the membrane-localized RsiW anti-sigma(W) factor mediates the transcriptional response to cell wall stress. Our findings are consistent with the idea that one function of ECF sigma factors is to coordinate antibiosis stress responses and cell envelope homeostasis.

Anti-Bacterial Agents↗
PubMed2002

Regulation of the Bacillus subtilis bcrC bacitracin resistance gene by two extracytoplasmic function sigma factors.

Bacitracin resistance is normally conferred by either of two major mechanisms, the BcrABC transporter, which pumps out bacitracin, or BacA, an undecaprenol kinase that provides C(55)-isoprenyl phosphate by de novo synthesis. We demonstrate that the Bacillus subtilis bcrC (ywoA) gene, encoding a putative bacitracin transport permease, is an important bacitracin resistance determinant. A bcrC mutant strain had an eightfold-higher sensitivity to bacitracin. Expression of bcrC initiated from a single promoter site that could be recognized by either of two extracytoplasmic function (ECF) sigma factors, sigma(X) or sigma(M). Bacitracin induced expression of bcrC, and this induction was dependent on sigma(M) but not on sigma(X). Under inducing conditions, expression was primarily dependent on sigma(M). As a consequence, a sigM mutant was fourfold more sensitive to bacitracin, while the sigX mutant was only slightly sensitive. A sigX sigM double mutant was similar to a bcrC mutant in sensitivity. These results support the suggestion that one function of B. subtilis ECF sigma factors is to coordinate antibiotic stress responses.

ATP-Binding Cassette Transporters↗
PubMed2002

[An analysis of the main causes of death in different industrial systems in Guangzhou].

OBJECTIVE: To study the main causes of death in workers from different industries in Guangzhou. METHODS: The industrial systems in Guangzhou were classified into six categories according to the Chinese Public Health Inspection Statistical Report. Baseline data on 79,547 workers, age > or = 35, were retrieved from individual health records under the Guangzhou Occupational Health Surveillance Record System established in 1989-1992. In this prospective cohort study, the workers' vital status and causes of death were followed up until 31 December 1998. Using SPSS 10.0, crude death rates were calculated and relative risks(RR) (95% CI) were estimated using Cox proportional-hazard models. RESULTS: (1) Among 79,547 workers were 49,355 men and 30,192 women, with mean age of (43.8 +/- 6.5) years, and 64% were aged 35-44. The mean age difference of workers in different industries was +/- 1 year. At baseline, 41% had been exposed to occupational hazards. Exposure was most prevalent in petroleum chemical industry(53.9%), followed by metallurgical industry, and the lowest exposure was in mechanical industry (30.2%). (2) The mean follow-up period was (8.0 +/- 1.3) years with 633,510 person-years. 1,577 workers had died with a total death rate of 248.9 per 100,000 person-years. The death rate in rubber industry was the highest, followed by metallurgical and petroleum chemical industries. Malignant neoplasms, vascular and respiratory diseases were most common, constituting 80.3% of all causes of death. (3) For all causes of death and the three main categories, the top three crude death rates were observed in rubber and petroleum chemical industries, and in the metallurgical industry except for vascular causes. The rubber industry had the highest crude death rate for all and vascular causes, and the metallurgical industry for malignant neoplasms and respiratory causes. (4) With the light industry as a reference (RR = 1.0), the metallurgical industry had the highest adjusted relative risks (RR) (95% CI) of 1.62(1.20-2.18) and 7.42(3.38-16.31) for malignant neoplasms and respiratory causes, respectively. The rubber industry had the highest RR of 1.69(1.40-2.04) for all causes. A significant RR of 2.03(1.43-2.88) for vascular causes was observed only in the rubber industry. CONCLUSIONS: The main causes of death varied from industry. Malignant neoplasms and respiratory diseases were the leading causes in metallurgical and petroleum chemical industries. In rubber industry, vascular and respiratory causes were most common. Preventive measures for disease control should be tailor-made for each industry.

Adult↗
PubMed2002

[A prospective cohort study on the effect of occupational dust exposure and smoking on mortality].

OBJECTIVE: To study the effect of dust exposure and smoking on mortality. METHODS: Based on the Guangzhou Occupational Health Surveillance Record System established in 1989-1992, 61,648 factory workers, aged > or = 30, occupationally exposed to dust and non-exposure to dust or any other hazardous substances(controls), were included in a prospective cohort study. RESULTS: (1) 28 were lost to follow-up. Malignant neoplasm was most common among 1,186 deaths. (2) Most subjects were male workers, aged 35 to 44, with secondary education, and married. 42.2% had ever smoked and 32.8% were ever-drinkers. (3) To compare with non-exposure, non-smoking + non-smoking and non-exposure respectively, the adjusted RR of death from all causes, malignant neoplasm and respiratory diseases were 1.24, 1.34 and 1.96 respectively for dust exposed workers(compared to control, P < 0.01), 1.16, 1.37 and 1.63 respectively for those smoking(compared to non-smoker except RR of death from respiratory diseases, P < 0.01), and 1.48, 1.85 and 3.12 respectively for those smoking and dust exposure, which were far greater than those either smoked or exposed to dust alone(P < 0.01). (4) The influence of dust exposure on death was mainly showed in occupational exposure to silica dust and wood dust. CONCLUSION: Both dust exposure and smoking may increase the mortality, and they had synergistic effect.

Adult↗