Insulin-stimulated production of nitric oxide is inhibited by wortmannin. Direct measurement in vascular endothelial cells

Hypertension is associated with insulin-resistant states such as diabetes and obesity. Nitric oxide (NO) contributes to regulation of blood pressure. To gain insight into potential mechanisms linking hypertension with insulin resistance we directly measured and characterized NO production from human umbilical vein endothelial cells (HUVEC) in response to insulin using an amperometric NO-selective electrode. Insulin stimulation of HUVEC resulted in rapid, dose-dependent production of NO with a maximal response of approximately 100 nM NO (200,000 cells in 2 ml media; ED50 approximately 500 nM insulin). Although HUVEC have many more IGF-1 receptors than insulin receptors (approximately 400,000, and approximately 40,000 per cell respectively), a maximally stimulating dose of IGF-1 generated a smaller response than insulin (40 nM NO; ED50 approximately 100 nM IGF-1). Stimulation of HUVEC with PDGF did not result in measurable NO production. The effects of insulin and IGF-1 were completely blocked by inhibitors of either tyrosine kinase (genestein) or nitric oxide synthase (L-NAME). Wortmannin (an inhibitor of phosphatidylinositol 3-kinase [PI 3-kinase]) inhibited insulin-stimulated production of NO by approximately 50%. Since PI 3-kinase activity is required for insulin-stimulated glucose transport, our data suggest that NO is a novel effector of insulin signaling pathways that are also involved with glucose metabolism.

Association of a 14-3-3 protein with CMP-NeuAc:GM1 alpha 2,3-sialyltransferase

CMP-NeuAc:GM1 alpha 2,3-sialyltransferase (ST-IV) was purified to homogeneity from rat brain. Microsequencing of the tryptic peptides derived from the purified enzyme revealed two amino acid sequences homologous to the 14-3-3 proteins. A polyclonal antibody was raised against purified ST-IV. A 33 kDa protein was co-immunoprecipitated from rat brain extracts with the anti-(ST-IV) antibody as detected by Western blot analysis. This protein was identified as a subtype of 14-3-3 family by an anti-(14-3-3) antibody. Screening of a rat brain lambda gt11 library using the anti-(ST-IV) antibody resulted in the identification of a cDNA clone coding for the subtype of 14-3-3 protein. These results indicate an association of the 14-3-3 protein with the sialyltransferase. Since the 14-3-3 protein has PKC inhibitor activities and the activity of sialyltransferases is, at least in part, regulated by PKC, the association of the 14-3-3 protein with ST-IV may indicate a role for this protein in the post-translational regulation of the sialyltransferase activity through the processes of phosphorylation and dephosphorylation.

Differential regulation of collagenase and stromelysin mRNA in late passage cultures of human fibroblasts

Nontransformed human fibroblast cell cultures have been extensively studied as an in vitro model for cellular senescence. Recently there has been considerable interest in using the human fibroblast in the identification of genes relevant to the process of replicative senescence. We demonstrated that in comparison with early passage cultures the expression of collagenase and stromelysin mRNAs and proteins was increased > 8 x in late passage cultures of human fibroblasts and, in addition, expression of Il-1 alpha, a cytokine that regulates collagenase and stromelysin expression, was also significantly increased in late passage cell cultures. These findings suggested the hypothesis that constitutive Il-1 alpha expression in late passage cells may coordinately regulate the age-associated increase in the expression of collagenase and stromelysin. To test this hypothesis we examined the effects of long-term Il-1 alpha treatment, serum starvation, and cycloheximide inhibition on collagenase and stromelysin mRNA levels in early and late passage human fibroblast cell cultures. Here we report that in late passage cell cultures, collagenase and stromelysin mRNAs respond differentially to Il-1 alpha, serum starvation, and cycloheximide addition. Continuous exposure to Il-1 alpha reduced the half-life of stromelysin mRNA but had little effect on the half-life of collagenase mRNA. In contrast to stromelysin, the collagenase mRNA level is dependent on serum factors. Collagenase is induced during recovery from cycloheximide inhibition, but stromelysin expression is not affected. These results establish that collagenase and stromelysin mRNAs are differentially regulated in both early and late passage human fibroblasts and suggest that the mechanisms responsible for the age-associated increase in the two mRNAs are different. In addition, these studies support the conclusion that continuous long-term exposure to Il-1 alpha, a condition that is characteristic of late passage cells, is not the factor responsible for the high levels of collagenase expression, but may be critical for stromelysin expression.

Regulation of glycolipid synthesis in HL-60 cells by antisense oligodeoxynucleotides to glycosyltransferase sequences: effect on cellular differentiation

Treatment of the human promyelocytic leukemia cell line HL-60 with antisense oligodeoxynucleotides to UDP-N-acetylgalactosamine:beta-1,4-N-acetylgalactosaminyl-transferase (GM2-synthase; EC 2.4.1.92) and CMP-sialic acid:alpha-2,8-sialyltransferase (GD3-synthase; EC 2.4.99.8) sequences effectively down-regulated the synthesis of more complex gangliosides in the ganglioside synthetic pathways after GM3, resulting in a remarkable increase in endogenous GM3 with concomitant decreases in more complex gangliosides. The treated cells underwent monocytic differentiation as judged by morphological changes, adherent ability, and nitroblue tetrazolium staining. These data provide evidence that the increased endogenous ganglioside GM3 may play an important role in regulating cellular differentiation and that the antisense DNA technique proves to be a powerful tool in manipulating glycolipid synthesis in the cell.

Adenovirus mediated gene transfer of vascular smooth muscle cells and endothelial cells in vitro

Introducing foreign gene(s) into vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) is the pre-requirement of gene therapy for cardiovascular diseases. We have explored the use of adenoviral vectors (Adv-CMV/LacZ) to transfer LacZ gene into cultured VSMCs and ECs. Our results demonstrated that adenoviral vectors transferred foreign gene into VSMCs and ECs high-efficiently with dose-dependent response pattern. The frequencies of transfection reached 100% at the viral titer of 10(9) pfu/ml. Comparing the sensitivities of VSMCs and ECs to adenoviral vectors, we found that ECs were more sensitive than VSMCs, of which the frequencies of transfection in ECs reached 80% while in VSMCs only 40% for 8 hrs after transfection. In addition, the transfection of ECs and VSMCs with adenoviral vectors was partly blocked by monoclonal antibodies to Fiber and Core protein of the adenoviral capsid, but not by monoclonal antibody to Hexon protein. It is suggested transfection of ECs and VSMCs with adenovirus vectors is mediated by Fiber or Core protein of adenoviral capsid proteins.

Enhanced adeno-associated virus vector expression by adenovirus protein-cationic liposome complex. A novel and high efficient way to introduce foreign DNA into endothelial cells

Adeno-associated virus vector (AAV), a non-pathogenic integrating vector, can integrate on chromosome 19 in humans. But its gene transfer efficiency is quite low. In this study we combined adenovirus (Adv-5) capsid protein or the Fiber protein of Adv with liposome, termed adenosome (adenovirus protein-cationic liposome complex). This complex can bring AAV/CMV-LacZ to the endothelial cells, and improve the efficiency of gene transfer. It may be a novel, specific, stable and safe gene delivery system and will be widely used in human gene therapy.

Breastfeeding practices in Chengdu, Sichuan, China

Barriers to increased breastfeeding rates in Chengdu, Sichuan were investigated in 1992 and 1993. Responses of focus groups showed that ignorance about breastfeeding and belief that the mother's milk was inadequate, and lack of support from their families, places of employment, and the health system acted as barriers to the women's breastfeeding their infants up to the age of four to six months. Subsequently, 363 mothers of 4- to 12-month-old Chengdu infants were surveyed. Although most mothers in both studies said breastmilk was the best food for their infant up to age of four to six months, only about half of the mothers breastfed for longer than one month. Both studies showed that infants who roomed with their mothers after birth were more likely to have been put to their mother's breast earlier, fed colostrum, breastfed somewhat longer, and exclusively breastfed for a somewhat longer period, although their mothers' infant feeding knowledge did not differ. The researchers conclude that Chengdu health workers should teach parents and parents-to-be more about breastfeeding, and that rooming-in be expanded in Chengdu hospitals.

[An epidemiological study on the characteristics of smoking behaviors among 910 young workers in Shangqiu City, Henan Province]

This paper dealt with an epidemiological investigation on the smoking behaviors of the young people in Shangqiu city, Henan province. The period of their working history was less than 5 years and their ages younger than 30 years. The interviewees were chosen from the hospitals, middle or professional schools, and large factories in the city. There were 587 males and 339 females included in this sample. Everyone was asked to complete the self-administered questionnaire in the workplace. The total number of sample was 926. The rate of respondence was 98.3%. Of the 926 questionnaires, 910 (98.3%) were identified as qualified. The investigation showed that the overall smoking rate was 32.1%, with male 64.2% and female 1.5%, respectively. The smoking rate of male was approaching the highest rate of adult males in our country, much higher than that of adolescents in school. The rates were parallelly increasing with years of working. About 50% of the young smokers began to be habitual since started their job, especially from the first four years of work. More than 80 percent of the smoking young workers were mild or light smokers, and did not smoke in "Ban Smoking Place". However, the most popular places for smoking were the place where there is a sign at their workplaces. They smoke most often with their colleagues and friends.

Expression of 72-kDa gelatinase and TIMP-2 in early and late passage human fibroblasts

The expression and regulation of 72-kDa gelatinase and TIMP-2 were examined in cultures of early and late passage human fibroblasts. In contrast to collagenase expression, which was low in early passage cells and highly expressed in late passage fibroblasts, 72-kDa gelatinase mRNA expression was enhanced only slightly in late passage cultures and 72-kDa gelatinase protein expression was similar in early and late passage cultures. In contrast to published reports of decreased TIMP-1 expression, TIMP-2 mRNA and protein were increased in late passage cells. Exposure to Il-1 alpha increased the steady-state level of 72-kDa gelatinase mRNA by 3x in early passage cells but had no effect on late passage cells. Although Il-1 alpha had no significant effect on TIMP-2 mRNA or on expression of 72-kDa gelatinase, in either early or late passage cells, Il-1 alpha increased the level of a TIMP-2-72-kDa gelatinase complex. Using monoclonal antibodies to TIMP-2 and to 72-kDa gelatinase we detected two forms of TIMP-2. One form was complexed to 72-kDa gelatinase and migrated with an apparent molecular weight of 72 kDa and the other migrated at the expected molecular weight of 21 kDa. Autoradiography in conjunction with Western analysis confirmed that in the late passage cell medium the newly synthesized 72-kDa gelatinase-TIMP-2 complex was increased even though the expression of 72-kDa gelatinase did not change. The present results establish that the regulation of 72-kDa gelatinase and TIMP-2 in early and late passage cultures of human fibroblasts are different from collagenase and TIMP-1 regulation. Further, they establish that in late passage cultures the activity of 72-kDa gelatinase may be regulated through the formation of a denaturation-resistant complex.

[Study and improvement of Reed-Frost model]

The purpose of this paper is to modify the Reed-Frost theory of epidemics with the underlying assumptions of the model including the occurrence of inapparent infections, and their influence on the course of the epidemic. With this model two epidemics were computed: (1) the Aycock outbreak of measles in a New England boy-boarding school in 1934; (2) the outbreak of chickenpox in a Shanghai kindergarten in 1950. The calculated and observed results were well in agreement. A substantial improvement in fitness was shown as measured by chi-square tests. As presented, the model offers a reasonably good explanation on the occurrence of inapparent infections and its effect on the pattern of the disease.

Early post-operative ankle pressure indices help predict late patency rates after femoro-distal vein bypass grafting

A prospective graft surveillance programme included 115 femorodistal autogenous vein bypass grafts that were patent when studied by measurements of ankle/brachial pressure indices (ABIs) at 3-5 weeks after operation. The grafts were followed for up to 3 years to determine whether early ABIs helped to predict subsequent failures, defined as graft thrombosis or graft or anastomotic stenosis causing diameter reduction greater than 75% treated by surgery or balloon dilatation. Receiving operating characteristics curves showed that resting ABIs predicted failure better than post-exercise ABIs or the differences between the two, and that an early resting ABI less than 0.85 was the optimal value to predict failure. Primary patency rates at 2 years were 88% for resting ABI greater than or equal to 0.85 and 36% for resting ABI less than 0.85 (p less than 0.0005). Most stenoses occurred in the grafts and not at anastomoses. Arteriographic grading of crural artery outflow was not significantly different for successful or failed grafts or for grafts with resting ABI greater than or equal to 0.85 or less than 0.85. The observation that late graft failure was 3-4 times more likely if the early post-operative ABI was low suggests that most graft failures result from faults relating to the operation.

Effectiveness of a worksite nutrition education activity in a factory in China

To evaluate the effectiveness of a worksite nutrition education activity in China, a two-group pretest-posttest nutrition education lesson was designed and carried out in two divisions (N = 240 in each division) of a steel tube factory in Chengdu, Sichuan. Special features of the program were nutrition education materials developed from both (a) the results of a pretest survey of the employees, and (b) focus group discussions conducted with factory hospital and workteam staff; a colloquial style; a slogan; and an illustrated handout depicting the new Chinese Dietary Guidelines and a proposed Food Guide. Analysis of variance, chi-square, and t-tests showed both significant increases (p < 0.05) in nutrition knowledge and attitude scores and significant improvements in dietary practices in the group receiving the education. It is concluded that the method is a useful and practical model for designing and developing worksite nutrition education in China.

[The use of Bayes' theorem in controlling the coming epidemic peak of epidemic meningitis in the 1980s]

To control the coming epidemic peak of epidemic cerebrospinal meningitis (ECM) in the 1980s in the regions with 100 million population in China, the mathematical models based upon Bayes' theorem (BT) were established and used respectively in provincial, regional and county's level. Reports of ECM from each ten-day's period or each month during the meningitis season were analysed to create forecast models. Records of ECM vaccinating rate in previous years were fully taken into account to modify the theoretical values. Calibration, split-sample, random-sample selection, as well as actual forecast tests, were used to check the efficiency of the models. The distribution of meningitis vaccine was planned according to the final predictive results. The incidence rates of ECM of above regions decreased obviously faster than other areas in China. Attributing the application of BT forecast research, it was estimated only in Henan province 79795 ECM cases; 4388 deaths and 21 million Yuan economic damage were avoided during the 4 years period, from 1985 to 1988.

An assessment of the use of Bayes' Theorem for forecasting in public health: the case of epidemic meningitis in China

A mathematical model based upon Bayes' Theorem (BT) was used to forecast the occurrence of epidemic cerebrospinal meningitis (ECM) in ten communities in North China. Reports of ECM from each ten-day period during the meningitis season and records of special population movement during 1960-82 were analysed to establish forecast models. Calibration, split-sample, random-sample selection, as well as actual forecast tests, were used to check the efficiency of the models. For all the tests, the theoretical occurrence of ECM forecast by the BT method was compared with the observational data. Since the BT method offers efficiency and convenience, it is recommended for use in planning for the prevention and control of ECM in China.