Risk factor analysis and risk prediction study of obesity in steelworkers: model development based on an occupational health examination cohort dataset

BACKGROUND

Obesity is increasingly recognized as a grave public health concern globally. It is associated with prevalent diseases including coronary heart disease, fatty liver, type 2 diabetes, and dyslipidemia. Prior research has identified demographic, socioeconomic, lifestyle, and genetic factors as contributors to obesity. Nevertheless, the influence of occupational risk factors on obesity among workers remains under-explored. Investigating risk factors specific to steelworkers is crucial for early detection, prediction, and effective intervention, thereby safeguarding their health.

METHODS

This research utilized a cohort study examining health impacts on workers in an iron and steel company in Hebei Province, China. The study involved 5469 participants. By univariate analysis, multifactor analysis, and review of relevant literature, predictor variables were found. Three predictive models-XG Boost, Support Vector Machine (SVM), and Random Forest (RF)-were employed.

RESULTS

Univariate analysis and cox proportional hazard regression modeling identified age, gender, smoking and drinking habits, dietary score, physical activity, shift work, exposure to high temperatures, occupational stress, and carbon monoxide exposure as key factors in the development of obesity in steelworkers. Test results indicated accuracies of 0.819, 0.868, and 0.872 for XG Boost, SVM, and RF respectively. Precision rates were 0.571, 0.696, and 0.765, while recall rates were 0.333, 0.592, and 0.481. The models achieved AUCs of 0.849, 0.908, and 0.912, with Brier scores of 0.128, 0.105, and 0.104, log losses of 0.409, 0.349, and 0.345, and calibration-in-the-large of 0.058, 0.054, and 0.051, respectively. Among these, the Random Forest model demonstrated superior performance.

CONCLUSIONS

The research indicates that obesity in steelworkers results from a combination of occupational and lifestyle factors. Of the models tested, the Random Forest model exhibited superior predictive ability, highlighting its significant practical application.

A nested case-control study of the effects of dust exposure, smoking on COPD in coal workers

BACKGROUND

Chronic obstructive pulmonary disease (COPD) represents a prevalent ailment, progressively surging within the ranks of coal mine laborers. The current study endeavors to elucidate the effects of dust exposure and smoking on COPD incidence amongst coal mine workers, while concurrently devising preventive strategies for this affliction.

METHOD

A nested case-control study was conducted encompassing 1,416 participants aged ≥ 18 years, spanning the duration from (2017-2018) until 2020. A meticulous matching process yielded a cohort of 708 COPD patients, each paired with a control subject, forming a harmonious 1:1 ratio. Multiple logistic regression analysis was employed to scrutinize the associations between smoking, dust exposure with COPD among coal workers.

RESULTS

The COPD prevalence within the cohort of coal workers under investigation amounted to 22.66%, with an accompanying incidence density of 0.09/person-year. Following meticulous adjustment for confounding variables, it was discerned that cumulative dust exposure within the range of 47.19 ~ (OR: 1.90, 95% CI: 1.05, 3.44), 101.27 ~ (OR: 1.99, 95% CI: 1.17, 3.39), as well as smoking indices of 72 ~ (OR: 1.85, 95% CI: 1.19, 2.88), 145 ~ (OR: 1.74, 95% CI: 1.17, 2.61), 310 ~ (OR: 1.85, 95% CI: 1.23, 2.77) engender an escalated vulnerability to COPD among coal workers. Furthermore, interaction analysis discerned an absence of both multiplicative and additive interactions between dust exposure, smoking, and COPD occurrence amidst coal workers.

CONCLUSION

Dust exposure and smoking were unequivocally identified as precipitating risk factors for COPD incidence within the population of coal workers, albeit devoid of any discernible interaction between these two causal agents.

Analysis of factors affecting nonalcoholic fatty liver disease in Chinese steel workers and risk assessment studies

BACKGROUND

The global incidence of nonalcoholic fatty liver disease (NAFLD) is rapidly escalating, positioning it as a principal public health challenge with significant implications for population well-being. Given its status as a cornerstone of China's economic structure, the steel industry employs a substantial workforce, consequently bringing associated health issues under increasing scrutiny. Establishing a risk assessment model for NAFLD within steelworkers aids in disease risk stratification among this demographic, thereby facilitating early intervention measures to protect the health of this significant populace.

METHODS

Use of cross-sectional studies. A total of 3328 steelworkers who underwent occupational health evaluations between January and September 2017 were included in this study. Hepatic steatosis was uniformly diagnosed via abdominal ultrasound. Influential factors were pinpointed using chi-square (χ2) tests and unconditional logistic regression analysis, with model inclusion variables identified by pertinent literature. Assessment models encompassing logistic regression, random forest, and XGBoost were constructed, and their effectiveness was juxtaposed in terms of accuracy, area under the curve (AUC), and F1 score. Subsequently, a scoring system for NAFLD risk was established, premised on the optimal model.

RESULTS

The findings indicated that sex, overweight, obesity, hyperuricemia, dyslipidemia, occupational dust exposure, and ALT serve as risk factors for NAFLD in steelworkers, with corresponding odds ratios (OR, 95% confidence interval (CI)) of 0.672 (0.487-0.928), 4.971 (3.981-6.207), 16.887 (12.99-21.953), 2.124 (1.77-2.548), 2.315 (1.63-3.288), 1.254 (1.014-1.551), and 3.629 (2.705-4.869), respectively. The sensitivity of the three models was reported as 0.607, 0.680 and 0.564, respectively, while the precision was 0.708, 0.643, and 0.701, respectively. The AUC measurements were 0.839, 0.839, and 0.832, and the Brier scores were 0.150, 0.153, and 0.155, respectively. The F1 score results were 0.654, 0.661, and 0.625, with log loss measures at 0.460, 0.661, and 0.564, respectively. R2 values were reported as 0.789, 0.771, and 0.778, respectively. Performance was comparable across all three models, with no significant differences observed. The NAFLD risk score system exhibited exceptional risk detection capabilities with an established cutoff value of 86.

CONCLUSIONS

The study identified sex, BMI, dyslipidemia, hyperuricemia, occupational dust exposure, and ALT as significant risk factors for NAFLD among steelworkers. The traditional logistic regression model proved equally effective as the random forest and XGBoost models in assessing NAFLD risk. The optimal cutoff value for risk assessment was determined to be 86. This study provides clinicians with a visually accessible risk stratification approach to gauge the propensity for NAFLD in steelworkers, thereby aiding early identification and intervention among those at risk.

Development and Internal Validation of Risk Assessment Models for Chronic Obstructive Pulmonary Disease in Coal Workers

Coal workers are more likely to develop chronic obstructive pulmonary disease due to exposure to occupational hazards such as dust. In this study, a risk scoring system is constructed according to the optimal model to provide feasible suggestions for the prevention of chronic obstructive pulmonary disease in coal workers. Using 3955 coal workers who participated in occupational health check-ups at Gequan mine and Dongpang mine of Hebei Jizhong Energy from July 2018 to August 2018 as the study subjects, random forest, logistic regression, and convolutional neural network models are established, and model performance is evaluated to select the optimal model, and finally a risk scoring system is constructed according to the optimal model to achieve model visualization. The training set results show that the logistic, random forest, and CNN models have sensitivities of 78.55%, 86.89%, and 77.18%; specificities of 85.23%, 92.32%, and 87.61%; accuracies of 81.21%, 85.40%, and 83.02%; Brier scores of 0.14, 0.10, and 0.14; and AUCs of 0.76, 0.88, and 0.78, respectively, and similar results are obtained for the test set and validation set, with the random forest model outperforming the other two models. The risk scoring system constructed according to the importance ranking of random forest predictor variables has an AUC of 0.842; the evaluation results of the risk scoring system shows that its accuracy rate is 83.7% and the AUC is 0.827, and the established risk scoring system has good discriminatory ability. The random forest model outperforms the CNN and logistic regression models. The chronic obstructive pulmonary disease risk scoring system constructed based on the random forest model has good discriminatory power.

Association of Chinese Visceral Adiposity Index and Carotid Atherosclerosis in Steelworkers: A Cross-Sectional Study

The Chinese Visceral Adiposity Index (CVAI) is an indicator of visceral adiposity dysfunction used to evaluate the metabolic health of the Chinese population. Steelworkers are more likely to be obese due to their exposure to special occupational factors, and have a higher prevalence of carotid atherosclerosis (CAS). This study aimed to analyze the special relationship between CVAI and CAS among steelworkers. A total of 4075 subjects from a northern steel company were involved in the cross-sectional study. Four logistic regression models were developed to analyze the correlation between CVAI and CAS. In addition, the restricted cubic spline was applied to fit the dose-response association between CVAI and CAS risk. In the study, the prevalence of CAS was approximately 25.94%. After adjustment for potential confounders, we observed a positive correlation between CVAI and CAS risk. Compared to the first CVAI quartile, the effect value odds ratio (OR) and 95% CI in the second, third, and fourth CVAI quartile were 1.523 (1.159-2.000), 2.708 (2.076-3.533), and 4.101 (3.131-5.372), respectively. Additionally, this positive correlation was stable in all subgroups except for female. Furthermore, we also found a non-linear relationship between CVAI and CAS risk (p nonlinear < 0.05). Notably, CVAI could increase the risk of CAS when higher than 106. In conclusion, our study showed that CVAI might be a reliable indicator to identify high-risk populations of CAS among steelworkers.

Risk Prediction for the Development of Hyperuricemia: Model Development Using an Occupational Health Examination Dataset

OBJECTIVE

Hyperuricemia has become the second most common metabolic disease in China after diabetes, and the disease burden is not optimistic.

METHODS

We used the method of retrospective cohort studies, a baseline survey completed from January to September 2017, and a follow-up survey completed from March to September 2019. A group of 2992 steelworkers was used as the study population. Three models of Logistic regression, CNN, and XG Boost were established to predict HUA incidence in steelworkers, respectively. The predictive effects of the three models were evaluated in terms of discrimination, calibration, and clinical applicability.

RESULTS

The training set results show that the accuracy of the Logistic regression, CNN, and XG Boost models was 84.4, 86.8, and 86.6, sensitivity was 68.4, 72.3, and 81.5, specificity was 82.0, 85.7, and 86.8, the area under the ROC curve was 0.734, 0.724, and 0.806, and Brier score was 0.121, 0.194, and 0.095, respectively. The XG Boost model effect evaluation index was better than the other two models, and similar results were obtained in the validation set. In terms of clinical applicability, the XG Boost model had higher clinical applicability than the Logistic regression and CNN models.

CONCLUSION

The prediction effect of the XG Boost model was better than the CNN and Logistic regression models and was suitable for the prediction of HUA onset risk in steelworkers.

A case control study on the relationship between occupational stress and genetic polymorphism and dyslipidemia in coal miners

Dyslipidemia is one of the known risk factors for cardiovascular disease, and its prevalence is increasing worldwide. At present, the study of dyslipidemia has gradually shifted from simple environmental or genetic factors to environment-gene interactions. In order to further explore the etiology and mechanism of dyslipidemia, we used occupational stress(OS) and LYPLAL1, APOC3 and SOD2 gene as research variables to explore their association with dyslipidemia.Here we used a case-control study to include Han workers from a coal mining enterprise in China to determine the association between study variables and dyslipidemia. Monofactor analysis showed that smoking, drinking, physical activity level, DASH diet score, sleep quality, BMI, hypertension, hyperuricemia, shift work, OS were significantly different between the two groups (P < 0.05). In the APOC3 rs2854116 dominant model, patients with CT/CC genotype had a higher risk of dyslipidemia than those with TT genotype. In SOD2 rs4880 recessive model, patients with GG genotype had a lower risk of dyslipidemia than those with AA/AG genotype, and the difference was statistically significant. We found that rs12137855 and OS, rs2854116 and OS, rs4880 and OS had joint effects, but no interaction based on the multiplication and addition model was found (P_interaction > 0.05). GMDR model showed that the rs12137855-rs2854116-rs4880-OS four-factor model had the highest cross-validation consistency and training-validation accuracy (P < 0.05), suggesting that there was a high-order interaction between them associated with dyslipidemia. We found that dyslipidemia in coal miners was related to OS and genetic factors. Through this study, we revealed the dual regulation of environmental factors and genetic factors on dyslipidemia. At the same time, this study provides clues for understanding the etiology and mechanism of dyslipidemia.

Influence of occupational exposure on hyperuricemia in steelworkers: a nested case-control study

BACKGROUND

Occupational exposure may be associated with an increased risk of developing hyperuricemia. This study sheds lights on the association between occupational exposure and hyperuricemia in steelworkers.

METHOD

A nested case-control study was conducted within a cohort of workers in steel companies to explore the association between occupational exposure and hyperuricemia. The case group consisted of a total of 641 cases of hyperuricemia identified during the study period, while 641 non-hyperuricemia subjects with the same age and gender distribution were randomly selected from the cohort as the control group.

RESULTS

The incidence rate of hyperuricemia among workers in the steel company was 17.30%, with an incidence density of 81.32/1,000 person-years. In comparison to the reference group, the risks of developing hyperuricemia for steelworkers undergoing ever shifts, current shifts, heat exposure, and dust exposure were 2.18 times, 1.81 times, 1.58 times and 1.34 times higher respectively. The odds ratios (ORs) and 95% confidence intervals (CIs) were 1.87(1.12-3.13) and 2.02(1.21-3.37) for the cumulative number of days of night work at 0-1,972.80 and ≥ 1,972.80 (days), respectively. Compared to the group with the cumulative heat exposure of 0 (°C/year), the ORs (95% CI) for the risk of developing hyperuricemia in the groups with the cumulative heat exposure of 0-567.83 and ≥ 567.83 (°C/year) were 1.50(1.02-2.22) and 1.64(1.11-2.43), respectively. The OR (95% CI) for the risk of developing hyperuricemia was 1.56(1.05-2.32) at the cumulative dust exposure of ≥ 30.02 (mg/m³/year) compared to that at the cumulative dust exposure of 0 (mg/m³/year). Furthermore, there was a multiplicative interaction between heat exposure and dust exposure in the development of hyperuricemia.

CONCLUSION

Shift work, heat, and dust are independent risk factors for the development of hyperuricemia in steelworkers. Additionally, there is a multiplicative interaction between heat exposure and dust exposure in the development of hyperuricemia. Interventions for shift work, heat and dust may help to reduce the incidence rate of hyperuricemia and improve the health of steelworkers.

MRI-based investigation on outflow segment of cerebral venous system under increased ICP condition

OBJECTIVE

Increased intracranial pressure (ICP) is responsible for causing most nervous system diseases to progress seriously, till death. Recently, volume-targeted therapeutic strategy against increased ICP, which works by releasing excessive intracranial liquid especially from the venous compartment, attracted a great deal of attention. Previous research by us found a structurally special "outflow segment cuff" that is located at the juncture of superior sagittal sinus (SSS) and the brain-bridging veins in porcine model. Sequential observation demonstrated that this special structure appeared to have functional abnormalities. Based on these findings, it was proposed to try and prove a further hypothesis that there exists a similar structure in human beings that might be of importance for cerebral venous system to intervene in volume-initiated ICP regulation. Meanwhile, the diameters of bridging veins under either increased or normal ICP are compared by means of magnetic resonance imaging (MRI).

METHOD

Forty patients who presented with increased ICP were selected to undergo 2D time of flight (TOF) venography and ten normal volunteers were taken as the control group. Increased intracranial pressure status was evaluated by using flash visual evoked potential (fVEP) technique. All the patients and volunteers underwent 2D-TOF MRI imaging for the following parameters: repetition time/echo time, 50/4.9 milliseconds; flip angle, 45 degrees ; field of view, 250x250 mm; matrix, 256x256 pixels; section thickness, 1.5 mm. Syngo fastview imaging system was used to process and analyze the targeted brain-bridging venous section.

RESULTS

By using 2D-TOF method in vivo, most bridging venous profiles as well as SSS and vicinal cortical veins could be clearly visualized. A short and narrow section, as previously described, obviously emerged because of MRI signal weakness even disappearing at the juncture of SSS and bridging veins in increased ICP patients. In combination with previous animal morphological findings we believe that this section with abnormal MRI signal could stand for the human counterpart of "outflow segment cuff" in porcine. Such a special structure could be observed within a majority of increased ICP patients (32/40 cases), whereas only one case presented the existence of similar imaging signal weakness. Furthermore, the diameters of the bridging veins in increased ICP group are statistically larger than the control group.

CONCLUSION

Intracranial venous compartment occupies about 70 to 80% blood volume inside the inflexible cranial cavity. Following volume-targeted rationale, ICP can be regulated effectively by the fluctuation of venous blood volume based on different aspects of morphology, biomechanics, and hemodynamics. In the present study, the coincidence of animal model and human venography in vivo offers strong evidences to support the hypothesis that venous hemodynamics, although passively, influences intracranial pressure environment through a possible key regulator - outflow segment narrow structure. The fact that this narrow formation and proximal vascular dilation appears more in patients under high ICP condition rather than in patients with normal pressure. Both narrow formation and proximal vascular dilation indicate its significant contribution to intracranial venous congestion, resulting from difficult drainage and the close relationship between intracranial venous volume and ICP.

Absorption spectra of the 4f electron transitions of the praseodymium complex with 1-cyclopropyl-6-fluoro-1,4-dihydro-7-(4-ethyl-1-piperazinyl) -4-oxo-3-quinoline carboxylic acid hydrochloride and its analytical application

The absorption spectra of the praseodymium complex with 1-cyclopropyl-6-fluoro-1,4-dihydro-7-(4-ethyl-1-piperazinyl)-4-oxo-3- quinoline carboxylic acid hydrochloride (NNFX) has been studied by normal and derivative spectrophotometry. The complex showed maximum absorption at 350 nm at pH 6.0. The stoichiometry of the Pr-NNFX complex was calculated by the molar ratio and continuous variation methods. The ratio of Pr to NNFX was 1:3. The absorption bands of the 4f electron transitions of the praseodymium complex with NNFX are enhanced markedly, especially the wavelength at 481 nm. Using the third-derivative spectrum, the calibration graph is linear over the range 2.5 x 10(-5)-3.5 x 10(-4) mol dm-3 for praseodymium. The detection limits (signal-to-noise ratio of 2) is 1.4 x 10(-6) mol dm-3. The relative standard deviation is 1.2% for 7.0 x 10(-5) mol dm-3 of praseodymium. A method for the direct determination of praseodymium in rare earth mixtures with good accuracy and selectivity is described.

Development of human fetal pancreas after transplantation into SCID mice

Only a small component of human fetal pancreas consists of beta cells, and yet this tissue is capable of normalizing the blood glucose levels of diabetic recipients when transplanted. The time taken to achieve this goal is several months, during which time the tissue proliferates and eventually differentiates into beta cells. The dynamics of beta cell development have not been described previously. We transplanted human fetal pancreas beneath the renal capsule of immunodeficient mice and analysed the grafts for a period of 12 weeks using antibodies against exocrine cells (lipase), endocrine cells and protodifferentiated duct cells. Exocrine cells constituted 48% of all epithelial cells in the untransplanted pancreas, with duct cells comprising 29% and endocrine cells 16% (beta cells 7%). The percentage of exocrine cells declined with time after transplantation, with only a small number undergoing apoptosis, and the duct cells increased, the values for these two cell types at 12 weeks being 20 and 57%, respectively. Both cell types appeared to proliferate equally for up to 8 weeks after transplantation, but only duct cells thereafter. Endocrine cells began to increase from 8 weeks after transplantation, representing 28% of epithelial cells (beta cells 11%) at this time. Intermediate cells, that is, cells expressing the characteristics of more than one type of mature pancreatic cell, were observed both in the ungrafted pancreas and after transplantation. The commonest intermediate cell type was duct/exocrine, with exocrine/endocrine and duct/endocrine cells also observed, suggesting active transdifferentiation from one cell type to another. We hypothesize that following the transplantation of human fetal pancreatic tissue, exocrine cells mostly transdifferentiate into duct cells and these eventually develop into endocrine cells, in particular beta cells.

In vitro dedifferentiation of fetal porcine pancreatic tissue prior to transplantation as islet-like cell clusters

The fetal porcine pancreas under experimental conditions can be transplanted in the form of explants or islet-like cell clusters (ICCs) to normalize blood glucose levels in diabetic recipients. ICCs are released from the collagenase-digested pancreas and require a 4- to 5-day culture period for their complete formation. In order to maximize insulin producing beta cell differentiation following transplantation, an understanding of ICC development is essential to utilize this alternative treatment for type 1 diabetes. In this study a role is proposed for exocrine cells in the generation of the multipotent pancreatic precursor cells during the culture period. Acinar cells undergo dedifferentiation during the initial stages of the culture period into multipotent pancreatic precursor cells, previously called protodifferentiated cells. The progressive loss of exocrine differentiation appears to involve rapid degranulation of zymogen granules by exocytosis and loss of the prominent secretory apparatus. These processes occur in parallel with a significant reduction in the expression of lipase in the period from day 0 to day 5 and simultaneously there is an increase in the epithelioid/ductal cell marker, cytokeratin 20. Using proliferating cell nuclear antigen, cell proliferation during the culture period does not appear to account for the increase in epithelioid/ductal cells. Further the rates of apoptosis and necrosis which were identified using the TUNEL technique and propidium iodide, respectively, do not appear to account for the reduction in exocrine cell numbers. Exocrine cell dedifferentiation appears to increase the pool of protodifferentiated cells which have the potential to develop into the insulin-producing beta-cell population following transplantation into the diabetic recipient

Envelope glycoprotein determinants of neutralization resistance in a simian-human immunodeficiency virus (SHIV-HXBc2P 3.2) derived by passage in monkeys

The simian-human immunodeficiency virus SHIV-HXBc2 contains the envelope glycoproteins of a laboratory-adapted, neutralization-sensitive human immunodeficiency virus type 1 variant, HXBc2. Serial in vivo passage of the nonpathogenic SHIV-HXBc2 generated SHIV KU-1, which causes rapid CD4(+) T-cell depletion and an AIDS-like illness in monkeys. A molecularly cloned pathogenic SHIV, SHIV-HXBc2P 3.2, was derived from the SHIV KU-1 isolate and differs from the parental SHIV-HXBc2 by only 12 envelope glycoprotein amino acid residues. Relative to SHIV-HXBc2, SHIV-HXBc2P 3.2 was resistant to neutralization by all of the antibodies tested with the exception of the 2G12 antibody. The sequence changes responsible for neutralization resistance were located in variable regions of the gp120 exterior envelope glycoprotein and in the gp41 transmembrane envelope glycoprotein. The 2G12 antibody, which neutralized SHIV-HXBc2 and SHIV-HXBc2P 3.2 equally, bound the HXBc2 and HXBc2P 3.2 envelope glycoproteins on the cell surface comparably. The ability of the other tested antibodies to achieve saturation was less for the HXBc2P 3.2 envelope glycoproteins than for the HXBc2 envelope glycoproteins, even though the affinity of the antibodies for the two envelope glycoproteins was similar. Thus, a highly neutralization-sensitive SHIV, by modifying both gp120 and gp41 glycoproteins, apparently achieves a neutralization-resistant state by decreasing the saturability of its envelope glycoproteins by antibodies.

Expression of the extracellular matrix proteins collagen I, collagen III and fibronectin and matrix metalloproteinase-1 and -13 in the skin of patients with inguinal hernia

Although abnormal collagen metabolism has been ascribed an important role in the high recurrence rates after surgical hernia repair, knowledge on tissue sampled in the region affected by inguinal hernias is poor. In the present study, we determined collagen type I and type III in the skin of adult patients with indirect and direct inguinal hernias by both immunohistochemistry and Western blot analysis. In addition, we quantified the immunohistochemical expression of fibronectin and matrix metalloproteinase (MMP)-1 and -13. The results indicated that the ratio of collagen type I/III was significantly decreased in the skin of patients with either indirect (n = 9) or direct hernia (n = 7), with a concomitant increase in collagen type III (p < 0.001 vs. controls, n = 7, without affection of the inguinal region). There was no significant difference between patients with indirect and direct hernia (p > 0.05). MMP-13 was not expressed in any of the skin samples investigated, whereas MMP-1 was found in the epidermis. Fibronectin was predominantly detected at the epidermal-dermal junction. MMP-1, MMP-13 and fibronectin levels were significantly different between patients and controls (p > 0. 05). We conclude that in contrast to the unchanged expression of fibronectin and MMP-1 and MMP-13, the decreased ratios of collagen tpye I/III with the basically increased amount of collagen type III could be of significant importance for the pathophysiology of hernias. The specific ratio collagen I/III probably reflects the altered structural integrity and mechanical stability of the connective tissue in both indirect and direct hernias. Moreover, our findings stress that hernias should be regarded as the manifestation of a systemic disease in the inguinal region with a genetic background, explaining the high recurrence rates after repeated suture repair, as well as the usefulness of surgical meshes in this clinical setting.

Expression and regulation of glucokinase in rat islet beta- and alpha-cells during development

Glucokinase (GK) is the rate-limiting enzyme in the glycolytic pathway of the beta-cell and, even in the rat fetus at 22-days gestation, immediately before birth, acts as a sensor of glucose influencing the rate of glucose utilization. However, when GK first appears in islets during beta-cell development is unknown. Whether GK is expressed in fetal glucagon-producing cells is also unknown. To determine this information, fetal rat islets were examined at 16-, 18-, and 22-days gestation. GK was identified immunocytochemically in both beta- and alpha-cells at all these ages, with the number of GK immunoreactive cells positively correlated to the fetal age from 16-22 days. Western blot analysis of islet protein extracts demonstrated the presence of GK, at 52 kDa, at 16 days and thereafter. To determine whether glucose had any effect on regulation of GK biosynthesis, fetal islets were cultured in medium containing a wide range of concentrations of glucose for 7 days. The amount of GK protein was significantly decreased in low concentrations of glucose and augmented at high concentrations. In conclusion, GK was expressed in both beta- and alpha-cells in fetal rat islets during development. GK is an integral part of the function of both of these cells at all stages in the development of the fetal islet.

[Fluorescence enhancement of the dysprosium-sulfosalicylic acid system by lanthanum and its application]

A fluorescence enhancement produced by adding lanthanum(III) to dysprosium-sulfosalicylic acid system was observed. La3+ enhanced the fluorescence intensity by two orders of magnitude compared with the system without La3+. The system was used for the determination of trace amount of dysprosium in the range of 3.0 x 10(-7)-1.0 x 10(-5) mol/dm3, and the detection limit was 8.0 x 10(-8) mol/dm3. The procedure was applied to the determination of dysprosium in synthetic rare earth samples and standard rare earth samples with satisfactory results.

Splicing efficiency of human immunodeficiency virus type 1 tat RNA is determined by both a suboptimal 3' splice site and a 10 nucleotide exon splicing silencer element located within tat exon 2

We have previously demonstrated that an exon splicing silencer (ESS) is present within human immunodeficiency virus type 1 (HIV-1)tat exon 2. This 20 nucleotide (nt) RNA element acts selectively to inhibit splicing at the upstream 3'splice site (3'ss #3) flanking this exon. In this report, we have used in vitro splicing of mutated RNA substrates to determine the sequences necessary and sufficient for the activity of the ESS. The activity of the ESS within tat exon 2 maps to a 10 nt core sequence CUAGACUAGA. This core sequence was sufficient to inhibit splicing when inserted downstream from the 3'ss of the heterologous Rous sarcoma virus src gene. Mutagenesis of the interspersed purines in the polypyrimidine tract of the tat exon 2 3'ss to pyrimidines resulted in a significant increase in splicing efficiency indicating that 3'ss#3 is suboptimal. The ESS acts to inhibit splicing at the optimized 3'splice sites of both the HIV-1 tat and RSV src constructs but with a reduced efficiency compared to its effect on suboptimal 3'splice sites. The results indicate that both the ESS and a suboptimal 3'splice site act together to control splicing at the 3'splice site flanking at exon 2.

Expression of the co-stimulatory molecule CD40 on melanoma cells

We have previously shown that one of the co-factors required for generation of T-cell responses, B7.1, is variably expressed on melanoma cells. In the present studies we have examined the expression of another important co-factor in T-cell responses, viz., CD40, and investigated regulation of its expression and possible function(s). PCR analysis revealed mRNA for CD40 in all 18 cell lines established from metastatic melanoma and the majority of those from 6 primary melanoma. CD40 protein was detectable in approximately 50% of the cell lines by flow cytometry and in sections from only 2 of 20 melanoma. Expression of CD40 protein was increased in 2 of 3 cell lines with constitutive CD40 expression by interferon-gamma but not by granulocyte/macrophage colony-stimulating factor, interleukin-2 or tumor necrosis factor-alpha. Interaction of monoclonal antibody with CD40 on melanoma cells resulted in an increase in their cell division but did not increase expression of the costimulatory factor B7. Our results suggest that CD40 expression on melanoma may have important effects on their biology. The influence of CD40 expression on T-cell responses to melanoma remains to be investigated.

Clinical responses and lymphoid infiltrates in metastatic melanoma following treatment with intralesional GM-CSF

Past studies in animal models with gene-transfected tumour cells have suggested that GM-CSF may have a role in immunotherapy of tumours as a result of the effects it has on antigen-presenting cells. The present (phase I) studies were carried out to examine whether intralesional injections of GM-CSF induce regression of subcutaneous metastases in patients with melanoma and influence lymphoid infiltrates in and around the metastases. Thirteen patients had 15-50 mg doses of GM-CSF injected into two subcutaneous metastases. In each case one metastasis received only five injections before excision whereas the other received weekly injections up to 6 months. Partial regression of injected and/or non-injected metastases was seen in three patients. The metastases from the responding patients that were treated with intralesional GM-CSF had marked increases and high absolute numbers of T cell infiltrates into the tumour, particularly of the CD4 T cell subset. There was an increase in IL-2R expression on the T cells and an increase in the number of Langerhans' cells infiltrating the tumours. The best predictors of clinical responses therefore appeared to be high relative increases and high absolute numbers of CD4+ T cells and Langerhans' cells within the treated tumour. These results provide support for further exploration of the role of GM-CSF in immunotherapy of human melanoma.

Expression of the co-stimulatory molecule B7 on melanoma cells

The induction of T-cell responses against tumor cells is believed to depend on both recognition of antigen and receipt of co-stimulatory signals from interaction of ligands such as B7 with its receptors CD28 or CTLA-4 on T cells. In the present study the expression of B7 on cultured human melanoma cells was studied at the mRNA level by reverse PCR analysis and surface expression by flow cytometric analysis with monoclonal antibodies (MAbs). PCR analysis revealed mRNA for B7 in 3 of 6 (50%) cultured primary melanoma and 8 of 19 (42%) cultures of metastatic melanoma. Analysis of B7 expression by flow cytometry using the BB1 MAb revealed low levels of expression in 3 of 10 melanoma that had mRNA for B7. In 2 of the latter (but not 4 other PCR+ lines) expression could be increased by culture in GM-CSF, IL-2, IFN-gamma and IFN-alpha 2. Our results indicate that although mRNA for B7 is present in 40-50% of melanoma cell lines, expression at the protein level is at low or undetectable levels in the majority of the cell lines. Expression of B7 protein was also not detected in studies on tissue sections from 11 primary and 9 metastatic melanomas.

Immunohistological examination of the relationship between metastatic potential and expression of adhesion molecules and 'selectins' on melanoma cells

Identification of antigens by monoclonal antibodies (MAbs) on sections of human melanoma by immunoperoxidase techniques was used to determine whether certain adhesion molecules and "selectin-like" molecules may be related to the metastatic potential of primary melanoma. The adhesion molecules examined were the leukocyte function antigen (LFA-1) and its ligand--intercellular adhesion molecule-1 (ICAM-1), the receptor alpha V beta 3 for vitronectin, its subunits alpha V and beta 3, and the CD36 receptor for thrombospondin (TSP). The criteria used to establish metastatic potential were relation of the molecules to tumor thickness and differences in expression: (i) between radial and vertical growth phases of the primary tumors and (ii) between 34 primary and 21 unrelated metastases. By these criteria ICAM-1, alpha V beta 3 and its subunit were associated with the malignant potential of primary melanoma. These molecules were not expressed on nevi or other skin cancers with low metastatic potential such as squamous (SCC) and basal cell carcinomas (BCC). In contrast, expression of TSP and the CD36 receptor for TSP were not related to metastatic potential. CD36 was expressed widely not only on melanoma but also on BCC, SCC and nevi. Similarly, the selectin-like molecule, CD44, was widely expressed on melanoma and non-melanoma carcinomas. The lymph node homing receptor, Leu 8, and the cutaneous lymphocyte antigen (CLA) were not detected on melanoma. Leu 8 was present on normal epithelium and SCCs, and common leucocyte antigen (CLA) was detected on lymphocytes in the epithelium and near melanoma. These results support previous suggestions that expression of ICAM-1 and V beta 3 integrin or its subunit beta 3 on melanoma may be a useful prognostic marker in primary melanoma. They do not support a role for CD44, Leu 8, CLA and TSP or its receptor CD36 in the metastatic process in melanoma.

Expression of the neuroglandular antigen and analogues in melanoma. CD9 expression appears inversely related to metastatic potential of melanoma

Immunohistological methods were used to examine the relation between the metastatic potential of melanoma and expression of the neuroglandular antigen (CD63) and other members of this family of molecules, CD53, CD37, CD9 and the target of an anti-proliferative antibody (TAPA-I), as well as MHC-class-I and -II antigens. The criteria used to establish metastatic potential were their relation to thickness of the primary melanoma, and differences in expression between vertical and radial growth phases of primary melanoma and between primary and metastatic melanoma. Studies on basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) were also included as controls for malignant skin cancers with low metastatic potential. Expression of CD9 and MHC-class-I antigen was found to be inversely related to thickness of the primary tumor, and CD9 was expressed predominantly on primary rather than on metastatic tumors. CD9 expression correlated with MHC-class-I expression on melanoma, and both were expressed on BCCs and SCCs having low metastatic potential, but not on compound nevi. CD63 and TAPA-I were expressed on nevi but not on SCC and BCC. Leu 13 is a molecule associated with TAPA-I in lymphomas, and was found to be expressed in sections from 5 out of 34 primary and 5 out of 21 metastatic melanoma. CD53 and CD37 were not detected on melanoma. Our results indicate that several members of the neuroglandular antigen are expressed in melanoma and that low expression of CD9 on primary melanomas might have prognostic significance with respect to the potential for metastasis.