Polyether-Thiourea-Siloxane Copolymer Based on H-Bonding Interaction for Marine Antifouling

By introducing thiourea and ether groups into MQ silicone resin polymer via free radical polymerization, a polyether-thiourea-siloxane (PTS) copolymer was synthesized. The characterization of the synthesized copolymer indicated the occurrence of H-bonding interactions and a narrow molecular weight polydispersity index. Antifouling coatings were produced by incorporating the synthesized copolymer and phenylmethylsilicone oil (PSO). The addition of a minute amount of copolymer enhanced the hydrophobicity of the coating by increasing its surface roughness. However, excessive addition of copolymer resulted in a significant deterioration of the coating surface smoothness. The copolymer improved the mechanical properties of the coating, but excessive addition decreased the crosslinking density and weakened the mechanical performance. With increasing copolymer addition, the leaching of PSO was significantly improved due to the change in the storage form of PSO in the coating caused by the copolymer. Based on the H-bonding interaction of the copolymer, the adhesion strength between the coating and the substrate was significantly improved. However, excessive addition of copolymer did not infinitely enhance the adhesion strength. The antifouling performance demonstrated that an appropriate amount of copolymer could obtain adequate PSO leaching efficiency, thereby effectively enhancing the antifouling performance of the coating. In this study, the prepared coating P₁₂ (12 g of PTS in 100 g of PDMS) showed the most effective antifouling performance.

De-ubiquitinating enzyme, USP11, promotes transforming growth factor β-1 signaling through stabilization of transforming growth factor β receptor II

The transforming growth factor β-1 (TGFβ-1) signaling pathway plays a central role in the pathogenesis of pulmonary fibrosis. Two TGFβ-1 receptors, TβRI and TβRII, mediate this pathway. TβRI protein stability, as mediated by the ubiquitin/de-ubiquitination system, has been well studied; however, the molecular regulation of TβRII still remains unclear. Here we reveal that a de-ubiquitinating enzyme, USP11, promotes TGFβ-1 signaling through de-ubiquitination and stabilization of TβRII. We elucidate the role that mitoxantrone (MTX), an USP11 inhibitor, has in the attenuation of TGFβ-1 signaling. Inhibition or downregulation of USP11 results in increases in TβRII ubiquitination and reduction of TβRII stability. Subsequently, TGFβ-1 signaling is greatly attenuated, as shown by the decreases in phosphorylation of SMAD2/3 levels as well as that of fibronectin (FN) and smooth muscle actin (SMA). Overexpression of USP11 reduces TβRII ubiquitination and increases TβRII stabilization, thereby elevating phosphorylation of SMAD2/3 and the ultimate expression of FN and SMA. Further, elevated expression of USP11 and TβRII were detected in lung tissues from bleomycin-challenged mice and IPF patients. Therefore, USP11 may contribute to the pathogenesis of pulmonary fibrosis by stabilization of TβRII and promotion of TGFβ-1 signaling. This study provides mechanistic evidence for development of USP11 inhibitors as potential antifibrotic drugs for pulmonary fibrosis.

ID: 115: TRKA TRANSACTIVATION BY LYSOPHOSPHATIDIC ACID REGULATES LUNG EPITHELIAL CELL MIGRATION

Background

Lysophosphatidic acid (LPA) is a bioactive lysophospholipid, which plays a crucial role in cell proliferation, migration, and differentiation. LPA exerts its biological effects mainly through cell-surface LPA receptors (LPA1-6), which belong to the G protein-coupled receptor (GPCR) family. Recent studies suggest that cross-talk between receptor tyrosine kinases (RTKs) and GPCRs modulates GPCR-mediated signaling. TrkA receptor is a RTK, which mediates nerve growth factor (NGF)-induced biological functions including cell migration in neuronal and non-neuronal tissues.

Methods and Results

Here, we show that LPA treatment of the murine lung epithelial cell line (MLE-12 cells) induced tyrosine phosphorylation of TrkA in both time- and dose-dependent manners. These effects were attenuated by downregulating the LPA1 receptor. Furthermore, LPA induces interaction between LPA1 and TrkA. Co-immunoprecipitation experiment reveals that c-terminus of LPA1 contains the binding site for TrkA. Further, we found that LPA1 and phosphorylated TrkA were co-localized in both the plasma membrane and cytoplasm. Pretreatment with a TrkA inhibitor attenuated LPA-induced phosphorylation of TrkA receptor and LPA1 internalization as well as lung epithelial cell migration.

Conclusion

These studies reveal a molecular mechanism for the transactivation of TrkA by LPA, and suggest that the cross-talk between LPA1 and TrkA regulates LPA-induced receptor internalization and lung epithelial cell migration.

This work was supported by the National Institutes of Health (R01HL091916 and R01HL112791 to Y.Z, R01GM115389 to J.Z.), American Heart Association 12SDG9050005 (J.Z.), American Lung Association Biomedical Research Grant RG350146 (J.Z.).

ID: 107: MITOXANTRONE INHIBITS TGFβ1-INDUCED SIGNALING THROUGH PROMOTING TGFβ RECEPTOR II DEGRADATION

Background

The transforming growth factor β1 (TGFβ1) signaling pathway and its downstream effects play a central role in the pathogenesis of pulmonary fibrosis. TGFβ induces the phosphorylation of transcriptional factors SMAD2 and SMAD3, thereby increasing the expression of smooth muscle actin (SMA) and fibronectin (FN), two key proteins in the development of fibrosis. This effect is mediated by two receptors, TGFβ receptor I (TβRI) and TGFβ receptor II (TβRII). The protein stability of TβRI has been well studied, while the molecular regulation of TβRII still remains unclear. This project elucidates the role that Mitoxantrone (MTX), a FDA-approved anti-cancer drug, has in the regulation of TGFβ1 signaling through the reduction of TβRII stability.

Methods and Results

To study TGFβ1 signaling, human fetal lung fibroblast cell line (MRC-5) was used. As expected, TGFβ1 treatment of MRC-5 cells induced phosphorylation of SMAD2 and SMAD3, with the ultimate expression of FN and SMA. These effects of TGFβ1 on FN and SMA were attenuated by MTX treatment, without altering SMAD2 and SMAD3 levels. To investigate the molecular mechanisms by which MTX regulates TGFβ1 signaling, we examined the expression of TβRI and TβRII. MTX reduced TβRII levels in time and dose dependent manners, while MTX had no effect on TβRI levels. MTX-induced TβRII degradation was inhibited by proteasome inhibitor (MG-132), not lysosome inhibitor (Leupeptin). Overexpression of HA tagged ubiquitin promoted MTX-induced TβRII degradation, suggesting that TβRII degradation by MTX is through the ubiquitin-proteasome pathway. Further, MTX increased TβRII ubiquitination and reduced TβRII neddylation, which has been known to negatively regulate TβRII stability by c-Cbl.

Conclusion

These studies reveal that treatment with MTX reduces the levels of TβRII by increasing its ubiquitination and reduction of TβRII neddylation; therefore, MTX is a potential anti-fibrotic drug for the treatment of pulmonary fibrosis.

The study is supported by NIH R01 HL112791 (to YZ), NIH R01GM115389 (to JZ), and American Lung Association Biomedical Research Grant RG350146 (to J.Z.).

ID: 108: DEUBIQUITINATING ENZYME 11 STABILIZES TGFβ RECEPTOR II AND REGULATES TGFβ1 SIGNALING IN PULMONARY FIBROBLAST

Background

Protein stability is regulated by ubiquitination and deubiquitination. The ubiquitin-deubiquitination system contributes to the regulation of tumor growth factor β1 (TGFβ1) signaling. TGFβ1 mediates its signaling and pro-fibrotic effects through binding to its receptors, TGFβ receptor I (TβRI) and TβRII. Here we reveal that deubiquitinating enzyme USP11 regulates TGFβ1 signaling through stabilization of TβRII.

Methods and Results

Bleomycin-induced pulmonary fibrosis is a wildly used murine model of pulmonary fibrosis. Analysis of murine lung tissue lysates from 3 weeks of bleomycin challenge revealed that USP11 levels were elevated in lung tissues from bleomycin-challenged mice. TGFβ1 plays a critical role in the pathogenesis of pulmonary fibrosis. TGFβ1 treatment of human lung fibroblast cells (HLF) induced tyrosine phosphorylation of USP11. To investigate the effect of USP11 in the TGFβ1 signaling, HLF cells were transfected with USP11 shRNA. USP11 shRNA reduced USP11 levels as well as TβRII expression in HLF. Overexpression of HA tagged USP11 (USP11-HA) enhanced TβRII lifespan. Co-immunostaining revealed that V5 tagged TβRII (TβRII-V5) and USP11-HA colocalized at plasma membrane and cytoplasm. TβRII ubiquitination was promoted by USP11 shRNA, while it was reduced by USP11-HA. Further, we investigated the role of USP11 in TGFβ1-mediated signaling, such as phosphorylation of SMAD2 and SMAD3. USP11-HA facilitated TGFβ1-induced phosphorylation of SMAD2 and SMAD3, which was attenuated in USP11 shRNA transfected HLF cells.

Conclusion

This study indicates that USP11 contributes to the pathogenesis of pulmonary fibrosis by regulating targeting TβRII for its deubiquitination and stabilization.

This work was supported by the National Institutes of Health (R01HL091916 and R01HL112791 to Y.Z, R01GM115389 to J.Z.), American Heart Association 12SDG9050005 (J.Z.), American Lung Association Biomedical Research Grant RG350146 (J.Z.).

γ₁34.5-deleted HSV-1-expressing human cytomegalovirus IRS1 gene kills human glioblastoma cells as efficiently as wild-type HSV-1 in normoxia or hypoxia

Pathophysiological hypoxia, which fosters the glioma stem-like cell (GSC) phenotype, is present in high-grade gliomas and has been linked to tumor development, invasiveness, and resistance to chemotherapy and radiation. Oncolytic virotherapy with engineered herpes simplex virus-1 (HSV-1) is a promising therapy for glioblastoma; however efficacy of γ₁34.5-deleted HSVs, which have been used in clinical trials, was diminished in hypoxia. We investigated the ability of a chimeric HCMV/HSV-1 virus, which expresses the human CMV PKR evasion gene IRS1 and is in preparation for clinical trials, to infect and kill adult and pediatric patient-derived glioblastoma xenografts in hypoxia and normoxia. Infectivity, cytotoxicity and viral recovery were significantly greater with the chimeric virus compared to the γ₁34.5-deleted virus, regardless of oxygen tension. The chimeric virus infected and killed CD133+ GSCs similarly to wild-type HSV-1. Increased activation of mitogen-activated protein kinase (MAPK) p38 and its substrate heat shock protein 27 (Hsp27) was seen after viral infection in normoxia compared to hypoxia. Hsp27 knockdown or p38 inhibition reduced virus recovery indicating that the p38 pathway plays a role in the reduced efficacy of the γ₁34.5-deleted virus in hypoxia. Together these findings demonstrate chimeric HCMV/HSV-1 efficiently targets both CD133+ GSCs and glioma cells in hypoxia.

Full-term pregnant women have higher lumbar epidural pressure than non-pregnant women: a preliminary report

The objective of this study was to compare the lumbar epidural pressure of full-term pregnant women with that of non-pregnant women. The epidural pressure of 20 full-term pregnant women and 15 non-pregnant women was measured during epidural needle insertion in the lateral position (T0), and at 30-s intervals following insertion (T1-T3), after the patient was turned supine (T4-T6), and after local anaesthetic injection (T7-T9). Results showed that the average epidural pressures following epidural insertion in the lateral position (average of T1-T3), in the supine position (average of T4-T6), and after local anaesthetic injection (average of T7-T9) were all significantly higher in the pregnant women compared with those who were not pregnant (p= 0.0293, 0.0109 and 0.0309, respectively). Epidural pressures increased significantly after women were turned supine (p < 0.001). Average epidural pressures were positive for all time points, T0-T9. It was concluded that the epidural pressure in the pregnant women was higher than in those who were not pregnant, both in the lateral and the supine position.

The role of bile duct reactive change in the pathogenesis of liver fibrosis due to hepatitis C

The question addressed here is: does the bile duct reactive component of hepatitis C disease progress during the progression of the disease to cirrhosis? The question is important because if the answer to the question is yes, then an important correllated question is: does the bile duct reactive component contribute to the fibrotic change which leads to cirrhosis? The first question is addressed in the present study of a series of liver biopsies taken at the four stages of liver fibrosis in patients with hepatitis C. Sixty-four patients with hepatitis who had been biopsied for staging purposes were reviewed retrospectively. The liver biopsies were routinely stained with antibodies for liver cells, bile duct cells, activated stellate cells and cells in S phase of the cell cycle and histochemical stains for collagen and basement membrane. Selective biopsies were stained for stem cells and oval cells. There was a progressive increase in metaplastic bile ductules but the increase did not reach a significant level until stages III and IV of fibrosis. There was a positive correlation between the number of ductules formed and the stage of liver fibrosis. The incidence of proliferating metaplastic ductules was low and did not change significantly during the progression of the stage of the fibrosis. Stains for oval cells and stem cells were negative. It is concluded that the answer to the question posed is: bile ductule reaction does increase during the development of cirrhosis caused by hepatitis C but the increase is due to bile ductular metaplasia, not due to proliferation.

Uncoupling of oxidative phosphorylation prevents the urinary alcohol level cycling caused by feeding ethanol continuously at a constant rate

The mechanism of the UAL cycle in the intragastric feeding model of alcoholic liver disease in the rat was investigated by administering dinitrophenol (DNP) with ethanol in the diet. The question was: is the rate of oxidative phosphorylation fluxuation essential for the cycle to occur? The question has been partially answered by showing that rotenone, which inhibits complex I, blocks the cycle by preventing the generation of NAD from NADH. This would inhibit ATP generation from complex I but would not affect oxidative phosphorylation by complex 2 and 3. Since the rate of O2 consumption is normal at the troughs of the cycle and decreases at the peaks of the cycle and the levels of ATP are reduced at the peaks of the cycle, it is likely that the rate of oxidative phosphorylation also cycles. Since 2-4 dinitrophenol (DNP) uncouples oxidative phosphorylation, it was anticipated that feeding it with ethanol would prevent the cycle from occurring. This proved to be the case. In addition, DNP caused energy wasting and prevented the increase in serum alanine aminotranspeptidase caused by ethanol feeding, probably by preventing the hypoxia which occurs at the peaks of the cycle.

Antisense anti-MDM2 oligonucleotides as a novel therapeutic approach to human breast cancer: in vitro and in vivo activities and mechanisms

The mouse double minute 2 (MDM2) oncogene has been suggested as a target for cancer therapy. It is amplified or overexpressed in many human cancers, including breast cancer, and MDM2 levels are associated with poor prognosis of several human cancers, including breast cancer, ovarian cancer, osteosarcoma, and lymphoma. In the present study, we investigated the functions of MDM2 oncogene in the growth of breast cancer and the potential value of MDM2 as a drug target for cancer therapy by inhibiting MDM2 expression with a specific antisense antihuman-MDM2 oligonucleotide (oligo). The selected antisense mixed-backbone oligo was evaluated for its in vitro and in vivo antitumor activity in human breast cancer models: MCF-7 cell line containing wild-type p53 and MDA-MB-468 cell line containing mutant p53. In MCF-7 cells, p53 and p21 levels were elevated, resulting from specific inhibition of MDM2 expression by the antisense oligo (AS). In MDA-MB-468 cells, after inhibition of MDM2 expression, p21 levels were elevated, although p53 levels remained unchanged. After i.p. administration of the antisense anti-MDM2 oligo, in vivo antitumor activity occurred in a dose-dependent manner in nude mice bearing MCF-7 or MDA-MB-468 xenografts. In both models, in vivo synergistically or additive therapeutic effects of MDM2 inhibition and the clinically used cancer chemotherapeutic agents irinotecan, 5-fluorouracil, and paclitaxel (Taxol) were observed. These results suggest that MDM2 have a role in tumor growth through both p53-dependent and p53-independent mechanisms. We speculate that MDM2 inhibitors, such as ASs, have a broad spectrum of antitumor activities in human breast cancers, regardless of p53 status. This study should provide a basis for future development of anti-MDM2 ASs as cancer therapeutic agents used alone or in combination with conventional chemotherapeutics.

[Bacterial genetic diversity in soils and their correlation with vegetation]

Soil is an important epicenter of biodiversity. Human activity has threatened such biodiversity through vegetation shift. As the major type of microbes, bacteria have played key roles in material cycling. Since simple morphological characters and the failure of the major portion of bacteria in surviving artificial cultivation have hindered bacterial diversity from analyses using traditional taxonomic approaches, bacterial diversity and its correlation with vegetation is less understood. In order to detour cultivation, tag serial sequencing strategy was developed in this study, in which a 26 base pair highly variable region has been chosen from 16S ribosomal RNA gene as variant-representing tags, ligated into serials and sequenced. Molecular bacterial diversity in soils has been determined using tag types, tag frequencies and diversity index as parameters. The correlation of bacterial diversity with vegetation has been explored as well. Bacterial diversity and differentiation correlate highly with contents of organic matter and nitrogen of soils and further vegetation.

Study on the metastatic mechanisms of human giant-cell lung carcinoma comparison between the strains C and D

The biologic characteristics of the two human giant-cell lung carcinoma strains with high (strain D) and low metastatic potential (strain C) were studied, including karyotype of chromosome, intracellular free calcium ([Ca2+]i), morphologic changes of cell surface and the expression of nm23-H1, p53, ras, c-myc, c-erbB2, bcl-2 genes and PCNA. The correlation between different biologic features and the metastatic potential of the two strains was analyzed. We found: 1) Both strains had the karyotypic abnormality of -13, -14, -15, +20, +21 with seven same marker chromosomes. Only strain D had the karyotypic abnormality of +7, -17, -18, +X, 7p+; 2) [Ca2+]i of the strain C (984.7 +/- 573.8) and D (517.6 +/- 216.6) was significantly different (p < 0.05). The amplitude of intracellular calcium oscillations of strain C was lower than the one of strain D; 3) strain C had more villous-like protrusions on the cell surface, whereas strain D had more bubble-like protrusions; 4) The expression of nm23-H1 and p53 protein of strain C was all higher than that of strain D. The expression of PCNA of strain C was lower than strain D; 5) nm23-H1 mRNA levels of strain C was lower than that of strain D. We consider that the karyotype of chromosomes, intracellular free calcium, the structure of cell membrane and the expression of nm23-H1 gene, p53 gene, PCNA could be closely related to the metastatic potential of human giant-cell lung carcinoma. They could be used as the sign for judging whether the tumor will metastasize in clinical practice as well as in judging the prognoses of patients.

Marked acceleration of the metastatic phenotype of a rat bladder carcinoma cell line by the expression of human gelatinase A

Numerous studies have reported a correlation between the production of gelatinases A and B by cancer cells and invasive and metastatic potential. It has been suggested that the expression of gelatinase A (72-kDa type IV collagenase) is associated more closely with the metastatic phenotype of malignant cells in vitro and in vivo than that of gelatinase B (92-kDa type IV collagenase). We have established a rat bladder carcinoma cell line, MYU3L, which is tumorigenic and locally invasive but is not metastatic to the distal organs in nude mice. The MYU3L cell line secretes pro-gelatinase B but not any detectable level of pro-gelatinase A. We undertook the present study to determine whether over-expression of gelatinase A can affect the metastatic potential of MYU3L cells. We transfected MYU3L cells with an expression vector containing human pro-gelatinase A cDNA under the transcriptional control of the SR alpha promoter. Two stable transfectants over-expressing gelatinase A activity were isolated. We assessed the biological behavior of the transfectants by an orthotopic site (urinary bladder) inoculation and an i.v. injection in nude mice. Our results demonstrate that the induced expression of human gelatinase A enzyme markedly accelerates the metastatic phenotype of the rat bladder carcinoma cell line MYU3L. Our results suggest that gelatinase A produced by tumor cells plays a major role in the metastatic process.

p53 gene mutations in human urothelial carcinomas: analysis by immunohistochemistry and single-strand conformation polymorphism

We examined 60 cases of human urothelial carcinomas (27 superficial and 33 deeply invasive) for the frequency of p53 gene mutations. Forty-two cases were analyzed by both the immunohistochemical and the single-strand conformation polymorphism (SSCP) methods, and the remaining 18 cases were assayed by SSCP alone. For the latter assay, exons 4 to 8 were amplified by polymerase chain reaction, and the amplified nucleotides were analyzed for the evidence of mutations by gel electrophoresis. When mobility shift was observed, direct nucleotide sequencing was performed to determine mutation sequence. Three superficial and eight deeply invasive carcinomas demonstrated evidence of mutations. Mutations involved various codons randomly. The fact that all tumors with mutations of the p53 gene except for one were of high nuclear grade (grade III) suggests that p53 mutation is associated with the progression of bladder cancers. Our results indicate that SSCP is a sensitive screening assay for detecting gene mutations. Immunohistochemical analysis is also a sensitive method but may yield false positive as well as false negative results.

Human chorionic gonadotropin beta-subunit synthesis by undifferentiated urothelial carcinoma with syncytiotrophoblastic differentiation

An undifferentiated deeply invasive ureteral carcinoma with syncytiotrophoblastic differentiation was analyzed for the synthesis of human chorionic gonadotropin beta-subunit by immunohistochemistry and Northern blot analysis. Human chorionic gonadotropin beta-subunit was localized immunohistochemically to syncytiotrophoblastic cells and scattered mononuclear tumor cells. Human chorionic gonadotropin beta-subunit gene was expressed at a high level by Northern blot analysis. To our knowledge, this is the first report demonstrating the synthesis of human chorionic gonadotropin beta-subunit at the transcriptional level in a urothelial carcinoma.

Differential expression of keratin 5 gene in non-tumorigenic and tumorigenic rat bladder cell lines

In this study, we attempted to find a gene or genes which were differentially expressed between a non-tumorigenic rat bladder cell line and a highly tumorigenic/metastatic bladder carcinoma cell line that was derived from the former after treatment in vitro with N-methyl-N-nitrosourea. We cloned a rat keratin 5 cDNA by a differential hybridization technique and found that all of the non-tumorigenic cells (7/7) and normal bladder tissue expressed keratin 5, but most of the tumorigenic cells (8/10) did not express keratin 5. Furthermore, in a spontaneously transformed cell line, keratin 5 expression was lost during the transformation process. These results suggest that loss of keratin 5 expression is closely associated with acquisition of a tumorigenic phenotype by rat bladder non-tumorigenic cells.

Effect of epidermal growth factor and transforming growth factor beta 1 on growth and invasive potentials of newly established rat bladder carcinoma cell lines

We established 5 rat bladder cell lines (MYU3L, MYU4, MYU6s, MYKU1L and MYP3). EGF stimulated DNA synthesis of all the cells in monolayer culture, regardless of the number of EGF receptors. In soft agar, only MYU3L formed colonies, and EGF enhanced their growth. However, EGF did not induce the other cells to grow in soft agar. In contrast, TGF-beta 1 inhibited the growth of the cells, but a tumorigenic cell and the cells which were established from large in vivo tumors were more resistant than the others to TGF-beta 1. We tested the effect of growth factors on the invasive potential of MYP3 cells (non-tumorigenic), MYU3L cells (tumorigenic/highly invasive but not metastatic) from newly established cell lines, and another metastatic cell line, LMC19. MYP3 expressed only a trace amount of 92-kDa gelatinase (MMP-9), whereas MYU3L expressed interstitial collagenase (MMP-1) and MMP-9, and LMC19 expressed 72-kDa gelatinase (MMP-2) and MMP-9. The release of MMP-2 in LMC19 was stimulated by TGF-beta 1, but EGF had no effect on the release of any MMPs in either type of cells. These observations suggest that EGF acted as a mitogen on all the cells tested, but did not enhance the malignant phenotype. Further, the loss of responsiveness to the suppressive effect of TGF-beta 1 may be an important step toward a malignant phenotype. Some of malignant tumors may utilize TGF-beta 1 for enhancing their invasive and metastatic potential.

Serum insulin and ECG abnormalities suggesting coronary heart disease in the populations of Mauritius and Nauru: cross-sectional and longitudinal associations

Cross-sectional associations between insulin and ECG abnormalities suggestive of 'possible' and 'probable' coronary heart disease (CHD) in the populations of Nauru (n = 568) and Mauritius (n = 3280) have been examined in both non-diabetic and diabetic subjects. Additionally, the longitudinal relationship between baseline insulin and incident ECG abnormalities has been explored in non-diabetic Nauruans (n = 177) over 5 years. Age-adjusted mean 2-hour serum insulin was generally higher in subjects with ECG abnormalities than those with a normal ECG, but the difference was significant only for non-diabetic Mauritian men (p < 0.01). There was no clear association between prevalence of ECG abnormalities and quintiles of fasting or 2-hr insulin in Mauritians, and in non-diabetic Nauruans there was a non-significant positive association between prevalence of ECG abnormalities and tertiles of 2-hr insulin. Logistic regression analyses showed a slight positive association between 2-hr insulin and ECG abnormalities in non-diabetic Mauritians (p = 0.06 in males, p = 0.09 in females), and non-diabetic male Nauruans (p = 0.054) independent of possible confounders. Fasting insulin was not associated in any group. In longitudinal analyses in Nauruans there were no significant differences in mean baseline fasting or 2-hr serum insulin between subjects who maintained a normal ECG and those who developed abnormalities consistent with 'possible CHD' (there were no changes suggestive of 'probable CHD'). The incidence of ECG changes suggesting 'possible CHD' was slightly higher in the upper tertile of baseline fasting insulin in both sexes and 2-hr insulin in females, but when other factors were accounted for, multiple logistic regression analyses did not support this finding. Data from the populations of Mauritius and Nauru do not support a major role for serum insulin in ECG abnormalities suggestive of CHD.

Effect of epidermal growth factor/transforming growth factor alpha and transforming growth factor beta 1 on growth in vitro of rat urinary bladder carcinoma cells

The response to growth factor stimulation was evaluated in clonally derived rat bladder carcinoma cell lines, ranging from nontumorigenic to tumorigenic and metastatic, in athymic nude mice. In the nontumorigenic cell line D44c, epidermal growth factor (EGF)/transforming growth factor (TGF) alpha weakly stimulated anchorage-dependent, but not -independent, growth. In tumorigenic/nonmetastatic cells (G1-200 Cl-17), EGF/TGF-alpha stimulated markedly anchorage-independent, but marginally anchorage-dependent growth, whereas TGF-beta 1 inhibited anchorage-independent growth and DNA synthesis. In the highly tumorigenic/metastatic cell line LMC19, EGF/TGF-alpha stimulated anchorage-dependent growth weakly and anchorage-independent growth strongly. In these cells, TGF-beta 1 did not inhibit anchorage-independent growth and DNA synthesis but increased the size of colonies irrespective of the presence of EGF, and some cells were scattered around colonies in soft agar. None of the cell lines showed evidence of TGF-alpha-specific mRNA transcription. Expression of TGF-beta 1 mRNA increased in parallel to the biological aggressiveness of the cell lines. Highly tumorigenic and metastatic cells also demonstrated gelatinase activity involving 72 kilodalton and 92 kilodalton types. Our data suggest that the growth-stimulatory effect of EGF/TGF-alpha in soft agar may be limited to cells that are already tumorigenic and that EGF/TGF-alpha is not effective in making nontumorigenic cells become tumorigenic (or in making nontumorigenic cells grow in soft agar).(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and medical care of hypertension in four ethnic groups in the newly-industrialized nation of Mauritius

Prevalence of hypertension was investigated in Mauritius in 2362 men and 2712 women among Hindu and Muslim Indian, Creole and Chinese ethnic groups aged 25-74 years. The age-standardized prevalence of hypertension varied from 9.4% to 17.3% in men and from 9.5% to 16.9% in women among the four ethnic groups and increased with age. The population mean values of systolic/diastolic blood pressure were 126/79 mmHg in men and 124/75 mmHg in women. The proportion of hypertensive persons aware of their condition was 50.5% in men and 66.6% in women. The proportion of treated and adequately controlled hypertensive patients was only 21.7% in men and 29.3% in women. Creoles had the highest mean value of systolic and diastolic blood pressure and the highest prevalence of hypertension whilst Muslim Asian Indians had the lowest values both in men and women. Further studies are needed to define the determinants of hypertension in the multi-ethnic Mauritian population. Diagnosis and treatment of hypertension need to be improved, especially in men and the Creole ethnic group.