Ligature-Induced Periodontitis Drives Colorectal Cancer: An Experimental Model in Mice

Periodontitis is a prevalent inflammatory oral disease associated with an increased risk of colorectal cancer. Experimental animal models are critical tools to investigate the effects and mechanisms of periodontitis on colorectal cancer. Several murine periodontitis models have been used in research, including oral gavage, periodontal pathogen injection, and ligature models. The role of experimental periodontitis caused by silk ligation in colorectal cancer remains unclear. In this study, we used an experimental periodontitis model on a colitis-associated colorectal cancer model and a spontaneous model, respectively. We observed the promotion of colorectal cancer in ligature-induced periodontitis mice compared to those control mice in 2 different models, as assessed by tumor number, tumor size, and tumor load. Since bacterial dysbiosis is an important feature of periodontitis, we next analyzed the oral and gut microbiomes using 16S ribosomal RNA gene sequencing. We found that the experimental periodontitis model reshaped the microbial community in the oral cavity and gut. In addition, we found a higher extent of programmed death 1 (PD-1)-positive CD8⁺ T-cell infiltration in tumor samples of the periodontitis group than in controls by immunofluorescence staining. Regarding the potential molecular mechanism, we transplanted the fecal microbiota of the periodontitis patient into mice and observed a tumor-promoting effect in the periodontitis group, assessed by tumor volume and tumor weight, together with a low level of INF-γ⁺ CD8⁺ T-cell infiltration in subcutaneous tumor mice. Taken together, we show that ligature-induced periodontitis model promotes colorectal cancer by microbiota remodeling and suppression of the immune response.

A study on the mechanism of PP2A in the recovery of SCI in rats through downregulation of MMP-9 via MAPK signaling pathway

OBJECTIVE

The aim of this study was to investigate the mechanism of action of protein phosphatase 2A (PP2A) in the recovery of spinal cord injury (SCI) in rats by downregulating matrix metalloproteinase 9 (MMP-9) via the mitogen-activated protein kinase (MAPK) signaling pathway.

MATERIALS AND METHODS

A model of SCI was first successfully established in rats. A total of three groups were set, including: sham operation group (A group), SCI group (B group) and PP2A group (C group). The Basso, Beattie and Bresnahan (BBB) motor function score and inclined plane test were adopted to evaluate the motor ability and limb muscle strength of rats in each group. The water content in spinal cord tissues was detected as well. Quantitative Polymerase Chain Reaction (qPCR) assay was performed to analyze the messenger ribonucleic acid (mRNA) expression levels of MAPK, MMP-2, and MMP-9 in spinal cord tissues. The expressions of inflammatory factors tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 in each group of rats were determined via enzyme-linked immunosorbent assay (ELISA). Western blotting (WB) was employed to measure the protein expression levels of MAPK, MMP-2 and MMP-9 in each group of rats. Additionally, the apoptosis of nerve cells in spinal cord tissues was analyzed through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

RESULTS

The BBB score was 8.8 points in C group at 5 d after operation, which was significantly different from that in B group (p<0.05). The slope in B and C groups was clearly lower than that in A group at each time point (p<0.001). Meanwhile, it was significantly higher in C group than that in B group at 5, 7 and 9 d (p<0.05). The edema rate rose notably in B group compared with A group (p<0.001). However, spinal cord edema was remarkably relieved after treatment with FRY720 (p<0.01), suggesting that PP2A agonist could treat SCI in rats. The levels of cytokines TNF-α, IL-1β and IL-6 were markedly higher in B group than those in A group (p<0.01). However, they were significantly reduced after treatment with PP2A agonist (p<0.01). In comparison with A group, B group exhibited remarkably decreased mRNA expression of MAPK and elevated mRNA expressions of MMP-2 and MMP-9 (p<0.01). However, C group exhibited an upregulated mRNA expression of MAPK (p<0.05), a downregulated mRNA expression of MMP-9 (p<0.01), and an undifferentiated mRNA expression of MMP-2 (p>0.05). Compared with B group, the protein expression level of MAPK significantly increased (p<0.05), while that of MMP-9 evidently decreased in C group (p<0.05). Besides, no statistically significant difference was observed in the protein expression level of MMP-2 between C group and B group (p>0.05). Compared with that in A group, the apoptosis rate significantly increased in B group (p<0.001). In addition, the apoptosis rate was significantly lower in C group than that in B group, showing a statistically significant difference (p<0.01).

CONCLUSIONS

PP2A downregulates MMP-9 through the MAPK signaling pathway, thereby conducing to the recovery of SCI in rats.

[An acute schistosomiasis case in Wuhan City imported from another province of China in 2020]

An imported case of acute schistosomiasis was reported in Wuhan City in 2020. The case was infected with Schistosoma by contact with the infested water due to playing water in the Yangtze River when working out of Hubei Province. The patient visited four medical institutions and the duration from onset to definitive diagnosis was 20 days. The patient's low awareness of schistosomiasis prevention and control knowledge and lack of diagnosis and treatment awareness for schistosomiasis among medical institutions were considered as main causes of the development of acute schistosomiasis and progression to severe case. Intensifying schistosomiasis health education among mobile populations and improving the awareness and capability of early diagnosis of schistosomiasis among clinicians are recommended.

Comparison of rapid maxillary expansion and pre-fabricated myofunctional appliance for the management of mouth breathers with Class II malocclusion

OBJECTIVE

Pre-fabricated myofunctional appliances and rapid maxillary expansion (RME) has been used for the treatment of mouth-breathers with Class-II malocclusion. This study aimed to compare the treatment effects of hyrax and pre-fabricated myofunctional appliance (T4K) for the management of mouth breathers with Class II Malocclusion in mixed dentition stage.

PATIENTS AND METHODS

Case records of mouth breathers with Class II Division 1 malocclusion patients treated at our institute with T4K or hyrax appliance between June 2015 to May 2019 were retrieved. The Pancherz analysis was used to compare the treatment effects.

RESULTS

Data of 28 patients (14 in each group) were compared. Significant advancement of maxilla was seen in both groups while mandibular length improved only with the T4K appliance. SNA and SNB changes were significantly greater in the T4K group. Molar relationship improved in both groups. Molar correction was obtained by 55.6% skeletal change and 44.4% dental change with RME. In the T4K group the corresponding values were 48.1% and 51.9% respectively.

CONCLUSIONS

Our results suggest that both pre-fabricated myofunctional appliance and RME are suitable for the treatment of mouth breathers with Class II malocclusion in the mixed dentition period. Sagittal correction of maxilla and mandible may be somewhat better with the T4K appliance. Although the dental compensation may be slightly more with the T4K appliance and it may inhibit the skeletal remodeling.

CSN6 promotes malignant progression of oral squamous cell carcinoma by down-regulating TIMP-2

OBJECTIVE

This study was designed to investigate the expression characteristics of CSN6 in oral squamous cell carcinoma (OSCC), and to further explore the mechanism of how it promotes the malignant progression of this cancer.

PATIENTS AND METHODS

The expressions of CSN6 and TIMP-2 in tumor tissue samples and adjacent normal ones collected from 36 OSCC patients were detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR), and the interplay between their expression levels and the clinical indicators or prognosis of OSCC patients was analyzed as well. Meanwhile, the expressions of CSN6 and TIMP-2 in OSCC cell lines were further verified via qRT-PCR. In addition, CSN6 overexpression and knockdown models were constructed using lentivirus in OSCC cell lines, CAL-27, and Tca8113. At the same time, transwell and cell wound healing assays were conducted to uncover the impact of CSN6 on the function of OSCC cells. Finally, the potential mechanism was explored using Luciferase reporter gene and recovery experiments.

RESULTS

In this work, qRT-PCR results revealed that the level of CSN6 in tumor tissues of OSCC patients was remarkably higher than that in adjacent normal ones. Compared with patients with low expression of CSN6, those with high expression CSN6 had a higher incidence of lymph node or distant metastasis and a lower overall survival rate. In vitro experiments revealed that silencing CSN6 remarkably attenuated the invasive, as well as migration capacities of OSCC cells while overexpression of CSN6 conversely enhanced those. Subsequently, in OSCC cell lines and tissues, TIMP-2 expression was remarkably reduced, which was negatively correlated with CSN6 level. Bioinformatics and Luciferase reporter genes demonstrated that CSN6 can target the corresponding sites of TIMP-2 promoter. In addition, cell recovery experiments suggested the existence of a mutual regulation between CSN6 and TIMP-2, which may synergistically modulate the malignant progression of OSCC.

CONCLUSIONS

The above results indicated that CSN6 was remarkably upregulated both in OSCC tissues and cell lines, which is remarkably relevant to the incidence of lymph node or distant metastasis and poor prognosis of OSCC patients. Additionally, we verified that CSN6 may promote OSCC malignant progression by regulating TIMP-2.

[Diagnostic and epidemiological features of the first two HIV-2 indigenous infections in Hunan province]

Objective: To study the diagnostic and epidemiological features of the first two HIV-2 indigenous cases in Hunan province. Methods: Blood samples from two individuals with "HIV antibody indeterminate" and HIV-2 specific band showed by HIV-1/2 western blotting method, were repeatedly collected and detected under HIV 1+2 strip immunoassay and PCR, in Changsha city, Hunan province, through March to November, 2017. An epidemiological survey was carried out at the same time. Results: Our findings showed that the two cases were sex partners, without histories of sexual contact with foreigners and the source of infection was unknown. Results from the HIV 1+2 antibody confirmation test showed that they were "HIV-2 antibody positive" . Through amplifying and sequencing the gag area of HIV-2 and BLAST, the similarity of HIV-2 strains presented as 98%. The results also showed that there were HIV-2 specific fragments in the two cases. Conclusion: HIV-2 indigenous cases had never been reported in China. These cases had brought new challenge on prevention, diagnosis and treatment of HIV/AIDS in China.

[Survey of the depressive disorders prevalence and related risk factors among male new drug users in certain drug rehabilitation center of Changsha city]

Objective: To understand the depressive disorders prevalence and related risk factors among new drug users in a male drug rehabilitation center. Methods: The cross-sectional study was used. A total of 250 new drug users from a male drug rehabilitation center were recruited during March, 2017. The drug users who only use new type of drugs single or use traditional drugs at the same time were collected as the new drug users. Their general information and drug-related information were collected by self-made questionnaire, and depressive disorders and sleep quality information were collected by the self-reported Patient Health Questionnaire-9 (PHQ-9) and the self-reported Pittsburgh Sleep Quality Index Questionnaire respectively. Logistic regression test was used to establish associations between variables. Results: Of all 250 drug users, the mean age (P(25), P(75)) was 30 (26, 35) years old, and 32.8% (82) had the depressive disorders. The individuals taking drug dose over 0.4 g daily before entering drug rehabilitation center had significantly more risk of the depressive disorders for 3.18 (1.71-5.90) than those not over 0.4 g daily.The individuals who bad sleep quality had significantly more risk of the depressive disorders for 6.07 (95%CI:3.31-11.12) than those had good sleep quality.The individuals who were depressive patients before the first drug use for 2.39 (95%CI: 1.12-5.10) than those were not depressive patients before the first drug use. Conclusion: There were a high rate of the depressive disorders among new drug users in the rehabilitation center; In addition, several risk factors including the individuals taking drug dose over 0.4 g daily and bad sleep quality, history of the depressive disorders were negatively associated with depressive disorders.

[The influence of chemotherapy-induced leucopenia on the disease-free survival of gastric cancer patients after radical gastrectomy]

Objective: To investigate the association between chemotherapy-induced leucopenia and patients' disease-free survival in gastric cancer patients who received radical gastrectomy. Methods: The clinical data of 273 gastric cancer patients who received radical gastrectomy and postoperative adjuvant chemotherapy between January, 2010 and December, 2015 in PLA 309(th) hospital was reviewed retrospectively. Results: A total of 195 (71.4%) patients experienced at least one time of leucopenia, while it was absent in the other 78 (28.6%) patients. The median disease-free survival of patients with or without leucopenia was 49.7 and 44.0 months respectively (P=0.009), leucopenia was an independent factor influencing patients' disease-free survival (HR=2.758, P=0.022), but there was no statistical difference between the disease-free survival of patients with different degrees and frequency of leucopenia (P=0.446, 0.123). Conclusion: Chemotherapy-induced leucopenia is a predictor of good prognosis for gastric cancer patients who receive radical gastrectomy.

[Effects of continuous positive airway pressure on periodic limb movements during sleep in patients with obstructive sleep apnea]

Objective: To investigate the effects of continuous positive airway pressure (CPAP) on periodic limb movements during sleep (PLMS) in patients with obstructive sleep apnea (OSA). Methods: The polysomnography (PSG) data of 828 consecutive OSA outpatients from January 2015 to January 2017 who had undergone overnight CPAP titration were analyzed retrospectively. On the basis of changes in periodic limb movements index (PLMI) values (cut off level≥15/h) from baseline PSG (BPSG) to CPAP titration PSG, patients were assigned to one of the following four groups: persistent, CPAP-emergent, CPAP-disappeared, and non-PLMS. Results: Among 828 patients, 756 (91.3%) were male and 72 (8.7%) were female. The mean age was (45.7±10.7) years old, the mean body mass index (BMI) was (27.6±3.5) kg/m(2). The rate of patients was 3.9% in the persistent group, 10.3% in the CPAP-emergent group, 7.5% in the CPAP-disappearance group, and 78.4% in the non-PLMS group. Multivariate Logistic regression analysis revealed that female appeared to be associated with the persistent group (P=0.004); older age and higher apnea-hypopnea index (AHI) on BPSG appeared to be associated with the CPAP-emergent group (P=0.012, 0.030). On the other hand, older age was negatively associated with the non-PLMS group (P=0.006). Conclusion: Elderly patients with higher AHI at BPSG may present with CPAP-emergent PLMS.

[Gender differences of REM related obstructive sleep apnea-hypopnea syndrome]

Objective: To explore the gender differences of rapid-eye-movement (REM) related obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods: Consecutive patients with primary complaint of snoring from Sleep Medicine Center of West China Hospital between January 2016 and November 2016 were included in the study. All participants underwent one night polysomnography (PSG) and Epworth sleep scale (ESS) was estimated. The patients diagnosed with OSAHS were classified as REM related OSAHS (REM-OSAHS group) and non-rapid-eye-movement (NREM) related OSAHS (NREM-OSAHS group) based on the PSG parameters. And the gender differences of demographic and polysomnograpic characteristics in both groups were compared. The associations between apnea-hypopnea index (AHI) and body mass index (BMI), neck circumference and waist circumference among patients with OSAHS were explored by multiple linear regression analysis. Results: A total of 1 258 patients were diagnosed with OSAHS. There were 997 (79.3%) male and 261 (20.7%) female among these patients, the mean age was (46.4±12.0) years old and mean BMI was (26.6±3.4) kg/m(2). There were 236 patients (18.8%) classified into REM-OSAHS group, and 1 022 patients (81.2%) classified into NREM-OSAHS group; the proportion of REM-OSAHS in female was significantly higher than that in male (34.1% vs 14.7%, P<0.001). After controlling for age, drinking, smoking, hypnotics, coffee, strong tea and sleep related parameters, in NREM-OSAHS group, AHI was positively correlated with BMI, neck circumference and waist circumference (P<0.001) both in male and female. In REM-OSAHS group, AHI was positively correlated with BMI, neck circumference and waist circumference in female (P<0.05), but only significantly correlated with BMI and waist circumference in male (P<0.05). Conclusions: REM-OSAHS is commonly seen in female OSAHS patients. Evaluation of the influences of anthropometric data on the severity of REM-OSAHS should consider the impact of gender.

Association between dietary intake of folate and MTHFR and MTR genotype with risk of breast cancer

We investigated the association between dietary intake of folate, vitamin B6, and the 5,10-methylenetetrahydrofolate reductase (MTHFR) genotype with breast cancer. A matched case-control study was conducted, and 413 patients with newly diagnosed and histologically confirmed breast cancer and 436 controls were recruited. Folate intake, vitamin B6, and vitamin B12 levels were calculated, and the MTHFR C677T and A1298C and MTR A2756G polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Breast cancer cases were generally older, older at first live birth, and younger at menarche, had a higher body mass index, were smokers, had higher energy intake, and more first-degree relatives with breast cancer as well as more live births compared to controls. With respect to energy intake, we found that higher energy intake were more likely to increase the risk of breast cancer. The MTHFR 667TT genotype was associated with a moderately increased risk of breast cancer when compared with the CC genotype, and a significant odds ratio (OR; 95% confidence interval, CI) was found (OR = 1.70, 95%CI = 1.06-2.73). Individuals carrying T allele were associated with higher risk of breast cancer when compared with C allele (OR = 1.34, 95%CI = 1.06-1.70). We did not find a significant effect of the MTHFR A1298C and MTR A2756G on the risk of breast cancer. We did not find any association between folate intake and MTHFR C677T polymorphisms. In conclusion, we found that the MTHFR C667T polymorphism is associated with the risk of breast cancer, indicating that this genotype plays a role in breast cancer development.

Neural activity in relation to temporal distance: differences in past and future temporal discounting

This study investigated the differences between past and future temporal discounting in terms of neural activity in relation to temporal distance. Results show that brain regions are engaged differently in past and future temporal discounting. This is likely because past temporal discounting requires memory reconstruction, whereas future temporal discounting requires the processing of uncertainty about the future. In past temporal discounting, neural activity differed only when preferences were made between rewards received one hour prior and rewards received further in the past. The peak amplitudes of P2 and P3 varied as the temporal distance increased from 2 weeks to 50 years. In future temporal discounting, neural activity differed only when preferences were evaluated between two delayed rewards. The delay conditions (6 months:5 years) and (6 months:50 years) had a significant influence on P2 and N2. Findings indicate the existence of different decision-making systems operating in past and future temporal discounting.

Effect of phytase supplementation to a low- and a high-phytate diet for growing pigs on the digestibilities of crude protein, amino acids, and energy1,2,3

Supplementation of microbial phytase usually improves the digestibility and utilization of phosphorus in feedstuffs of plant origin. The effect of phytase supplementation on the digestibilities of AA also has been examined, but the results have been inconsistent. This study was carried out to determine the effect of phytase (Natuphos) supplementation, at a rate of 2,000 phytase units/kg, to two basal diets on the apparent ileal digestibilities (AID) of GE, CP, and AA, and on the apparent total-tract digestibilities (ATTD) of CP and GE. The basal diets contained 18% CP and were formulated (as-fed basis) to contain either a low (0.22%) or high content (0.48%) of phytate P. The high-phytate diet contained 20% rice bran, which is a rich source of phytate and has low intrinsic phytase activity. Eight barrows (average initial BW = 40.6 kg), fitted with a simple T-cannula at the distal ileum, were fed the four diets according to a replicated 4 x 4 Latin square design. The pigs were fed twice daily at 0800 and 2000, equal amounts each meal, at a rate of 2.4 times the daily maintenance requirement for ME. Each experimental period comprised 14 d. Ileal digesta were collected from 0800 to 2000 on d 12, 13, and 14. Feces were collected from 0800 on d 8 until 0800 on d 12. Chromic oxide was used as the digestibility marker. The AID of GE, CP, and AA and the ATTD of CP and GE were less in the high- than in the low-phytate diet (P < 0.01). With the exception of glutamic acid, phytase supplementation did not affect (P > 0.10) the AID of CP and AA. There was no effect (P > 0.05) of phytase on the ATTD of CP and GE. These results show that if a response occurs to phytase supplementation, it is independent of the dietary phytate content.

Effect of phytase supplementation to diets for weanling pigs on the digestibilities of crude protein, amino acids, and energy1,2,3

Four experiments were conducted with weanling pigs fitted with a simple T-cannula at the distal ileum, to determine the effect of phytase supplementation to four diets on the apparent ileal digestibilities (AID) of CP and AA, and the apparent total-tract digestibilities (ATTD) of CP and DE. Phytase (Natuphos, DSM Food Specialties, Delft, The Netherlands) was supplemented at rates of 0, 500 or 1,000 FTU/kg to the four diets. A 20% CP (as-fed basis) corn-soybean meal diet was used in Exp. 1; a 20% CP wheat-soybean meal diet in Exp. 2; a 20% CP wheat-soybean meal-canola meal diet in Exp. 3; and a 19% CP barley-peas-canola meal diet in Exp. 4. In each experiment, six barrows, fitted with a simple T-cannula at the distal ileum, were fed the basal plus phytase-supplemented diets according to a repeated 3 x 3 Latin square design. Each experimental period comprised 14 d. The piglets were at fed 0800 and 2000 daily, equal amounts for each meal, at a daily rate of at least 2.4 times the maintenance requirement for ME. Feces were collected from 0800 on d 8 until 0800 on d 12 of each experimental period. Ileal digesta were collected from 0800 to 2000 on d 12, 13, and 14. Chromic oxide was used as the digestibility marker. The average initial and final BW (average of all experiments) were 7.9 and 16.5 kg, respectively. Phytase supplementation did not improve the AID of CP and AA in Exp. 1, 2, and 4; however, there were improvements (P < 0.05) or tendencies (P < 0.10) toward improvements in the AID of CP and AA or the ATTD of CP and the content of DE with phytase supplementation in Exp. 3. These results suggest that the AA response factor to microbial phytase supplementation depends on diet composition.

Concentration-time exposure index for modeling soil fumigation under various management scenarios

Best management decisions in soil fumigation require informed management selections of soil type, field geometry, application dosage, and depth to maximize fumigant distribution for efficacy and minimize off-site transport for environmental safety. An efficacy- or exposure-based concentration-time exposure index (CTEI) was used to serve as a continuous quantitative efficacy assessment for soil fumigation by subsurface drip irrigation using numerical model simulations. The CTEI was defined as the ratio between the soil volume where concentration-time (CT) exceeded a threshold value for a particular pest-fumigant combination and the total soil volume required for fumigation treatment. Applications of CTEI as a simple efficacy index were demonstrated by simulating combinations of three soil types (loam, sandy loam, sand); three field configurations consisting of 102- and 203-cm-wide bed systems and a flat surface system; three application depths (15, 30, 45 cm); and two application rates (82 and 327 kg ha(-1)) for 1,3-dichloropropene against citrus nematode (Tylenchulus semipenetrans) using a threshold air-phase CT value of 12 microg h cm(-3) obtained from a separate field study. For soil fumigation by subsurface drip irrigation, the order of importance in optimizing CTEI was soil type, depth of application and depth of treatment, dosage, and field configuration. Model simulation using CTEI as a numeric efficacy index can be an effective alternative to assist in the planning of field trials for making final management decisions concerning soil fumigation or other pesticide applications.

Smoking and mortality in 81,344 drivers in Guangzhou, China

OBJECTIVES

Previous studies on drivers focused on the effect of their exposure to vehicle exhaust and there is little evidence of the effect of smoking. This cohort analytical study aimed to examine the mortality of drivers relative to smoking and professional driving in Guangzhou, China.

METHODS

Information on demographic characteristics, type of driver (professional and non-professional), smoking, and drinking were retrieved from medical records of drivers who applied for driving licences from March to December 1992. Vital status and causes of death of 81,344 men aged 30 or above were ascertained to the end of September 1999 (follow up, mean=7.14 years, median=7.17 years).

RESULTS

At baseline, the mean (SD) age was 40.8 (5.6) years. One third were professional drivers; 49.0% were daily smokers. 858 Deaths were identified. The relative risk of overall mortality for ever smoking was 1.24 (95% confidence interval (95% CI) 1.07 to 1.44) after adjusting for age, alcohol drinking, education, and type of drivers. Compared with non-professional drivers, professional drivers had similar risks of death, and their relative risk of overall mortality for ever smoking was 1.35 (1.06 to 1.71).

CONCLUSIONS

Smoking is a more important cause of death than professional driving itself. The results show serious public health problems in the early stage of the tobacco epidemic and support urgent measures to help drivers stop smoking.

Delta-aminolevulinate dehydratase polymorphism and blood lead levels in Chinese children

This study investigated the relationship between the delta-aminolevulinate dehydratase (ALAD) isozymes and the blood lead levels of Chinese children. The purpose of this study was to determine the precise ALAD genotyping in Chinese children and identify the contribution of the ALAD genotype to the body lead burden. Blood samples were obtained from 109 boys and 120 girls. These children were 6-10 years old and from a single primary school. Both the school and their homes were within a community in which a large smelter was located. An environmental questionnaire was obtained for each subject, and blood lead levels and ALAD isozyme phenotype were analyzed in a double-blinded fashion. The blood lead levels of 229 children ranged from 4.5 to 26.4 microg/dl; the mean was 10.3 microg/dl and the standard deviation was 3.3 microg/dl. The gene distribution of the ALAD isozyme phenotypes in these environmentally exposed children was ALAD 1-1 (92%), ALAD 1-2, (8%), and ALAD 2-2 (0%). The mean blood level of the environmentally exposed children, who were homozygous for the ALAD1 allele, was 9.7 microg/dl; the mean for those who were heterozygous for the ALAD2 allele was 11.7 microg/dl. Using the t test, the means of the groups were different at the level of t=2.2058, P<0.05. Step-wise regression and multiple analyses of covariance were employed to control the confounders to measuring the independent contribution of the ALAD genotype on blood lead levels. After controlling the confounders, the contribution of the ALAD genotype to the blood lead level was greater and still statistically significant (F=7.3201, P<0.01). These results indicate that individuals carrying the ALAD2 allele are more likely to have sustained increases in blood lead levels when exposed to a lead-contaminated environment.

Smoking and exposure to occupational hazards in 8,304 workers in Guangzhou, China

This cross-sectional study aimed to describe the pattern of smoking in relation to occupational hazard exposure in a working population in Guangzhou, China. In 1994, data on smoking and occupational hazard exposure from occupational health records of 8,304 subjects aged 35 years or older from 47 randomly selected factories were studied. About 49% of the men and 55% of the women were exposed to dust, chemicals or other hazards. The prevalence of smoking was 56.1% in men and 2.0% in women. The prevalence of smoking in men was higher in those who were younger, with primary education or who were workers. In women, those who were older, with primary education or in management jobs had higher smoking prevalence. In men and women, subjects who were exposed to occupational hazards had higher smoking prevalence: the highest (71.6%) was found in male workers exposed to dust. Urgent tobacco control measures are needed to prevent the epidemic of smoking-related and occupation-related diseases in the workplace in China.

Byssinosis in Guangzhou, China

OBJECTIVES

To study the prevalence of byssinosis and other respiratory abnormalities in workers exposed to cotton dust in Guangzhou in two factories that processed purely cotton.

METHODS

All the 1320 workers exposed were included. The controls were 1306 workers with no history of occupational dust exposure. Total dust and inhalable dust were measured by Chinese total dust sampler and American vertical elutriator respectively. A World Health Organisation questionnaire was used. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured by a Vitalograph spirometer.

RESULTS

The median inhalable dust concentrations ranged from 0.41 to 1.51 mg/m3 and median total dust concentrations from 3.04 to 12.32 mg/m3. The prevalence of respiratory abnormalities in the cotton workers were (a) typical Monday symptoms 9.0%; (b) FEV1 fall by > or = 5% after a shift 16.8%; (c) FEV1 fall by > or = 10% after a shift 4.2%; (d) FEV1 < 80% predicted 6.1%; (e) FEV1/FVC < 75% 4.0%; (f) cough or phlegm 18.2%; (g) chronic bronchitis 10.9%; and (h) byssinosis, defined by (a) plus (b) 1.7%. With the exception of (d), most of the prevalences increased with increasing age, duration of exposure, and cumulative inhalable dust exposure. No increasing trends of respiratory abnormalities were found for current total dust, inhalable dust, and cumulative total dust concentrations. Compared with controls, after adjustment for sex and smoking, with the exception of (d), all the pooled relative risks of respiratory abnormalities were raised for cotton exposure.

CONCLUSION

It is concluded that cumulative inhalable cotton is likely to be the cause of byssinotic symptoms, acute lung function decrements, cough, or phlegm, and chronic bronchitis.