Urinary excretion of nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for nasopharyngeal carcinoma in southern China

The hypothesis that endogenous synthesis of nitrosamines from dietary precursors is a risk factor for nasopharyngeal carcinoma (NPC) in China was tested by applying the nitrosoproline (NPRO) test to subjects living in high- and low-risk districts for NPC in Zangwu county, Guangxi region, in southern China. Samples of 12-h urine were collected from 77 subjects: (a) before any treatment; (b) after ingestion of proline; and (c) after ingestion of proline together with vitamin C. NPRO, other nitrosamino acids, and nitrate were measured as indices of exposure to preformed and endogenously formed nitrosamines or their precursors. The NPRO level after proline intake was significantly increased in subjects from the high-risk area (P = 0.012) and markedly reduced after ingestion of ascorbic acid (P = 0.007), but such an effect was not seen in subjects from the low-risk area. Levels of N-nitrosothiazolidine-4-carboxylic acid and the sum of nitrosamino acids in subjects in the high-risk area were significantly reduced by ascorbic acid (P < 0.01) but were not reduced in subjects from the low-risk area. The urinary nitrate level was about twice as high in subjects from the high-risk area. In subjects from high- and low-risk areas combined, NPRO levels in any of the three dose groups were highly correlated with nitrate levels (P = 0.0001). These results demonstrate a higher potential for endogenous nitrosation in subjects living in the high-risk area of NPC and suggest the occurrence of nitrosation inhibitors in the diet consumed in the low-risk area.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of nitric oxide in the blastogenic response deficiency in splenocytes from spontaneously hypertensive rats

It has been shown that spontaneously hypertensive rats (SHR) exhibit some abnormalities in their immune system. These include a reduced delayed hypersensitivity response, a reduction in the number of rosette-forming cells and a decreased lymphocyte blastogenic response. In this study, we further investigated the blastogenic responses of splenocytes, thymocytes, and T-enriched lymphocytes from SHR. In SHR splenocytes, the blastogenic responses to concanavalin A (Con A), phytohemagglutinin (PHA), interleukin-2 (IL-2), and phorbol 12,13-dibutyrate (PDB) plus ionomycin were significantly reduced compared with those from Wistar-Kyoto rats (WKY). In SHR thymocytes and T-enriched lymphocytes, the blastogenic responses to these activators were the same as in WKY rats. The IL-2 production by SHR splenocytes was similar to that of WKY. To elucidate the possible mechanism responsible for the blastogenic defects in SHR splenocytes, the involvement of the nitric oxide (NO) synthetic pathway was studied. The inhibition of NO synthesis by NG-monomethyl-L-arginine (L-NMMA) corrected the defect in SHR splenocytes. L-NMMA had no effect on the splenocytes, thymocytes, or macrophage-depleted splenocytes from WKY or on thymocytes or macrophage-depleted splenocytes from SHR. The removal of macrophages from SHR splenocytes also corrected the blastogenic defect in these cells. Furthermore, the NO synthesis in Con A stimulated SHR splenocyte culture medium was statistically significantly higher than that in WKY. These results suggested that overproduction of nitric oxide by SHR macrophages may be responsible for the SHR splenocyte blastogenic defect.

Surveillance and care of four Chinese hemophiliacs with human immunodeficiency virus (HIV) infection

Four Chinese hemophiliacs with HIV infection have been followed up in Zhejiang Province since 1985. A plan for optimal care of HIV seropositive patients was proposed, including surveillance and care; clinical follow-up and preventive education of asymptomatic HIV seropositive patients; keeping the disease confidential so as not to stir up unnecessary social unease; propaganda and health education about acquired immunodeficiency syndrome (AIDS); treatment with traditional Chinese medicines; and regular surveillance of family members and medical personnel. This plan is regarded as feasible and effective for the prevention and control of AIDS in China.

The effect of prednisone on pancreatic islet autografts in dogs

Prednisone was shown to induce hyperglycemia in dogs submitted to total pancreatectomy and pancreatic islet autotransplantation. The hyperglycemia caused by a 10-day course of prednisone, 1 mg/kg/day, starting on the day of operation was reversible within 1 week after steroid discontinuance. Three weeks after prednisone was stopped, there was no detectable adverse effect on glucose homeostasis as judged by fasting blood sugar levels and intravenous glucose tolerance test results. Four months after transplantation, glucose disappearance was delayed in animals previously treated with the prednisone compared with those previously treated with prednisone plus insulin or control animals. This was accompanied by lower insulin values on intravenous glucose tolerance testing and suggests a long-term subtle effect on islet function. The mechanism of the steroid effect is not known. However, this model could be used to test the diabetogenicity of other immunosuppressive agents including cyclosporine, FK 506, and azathioprine.

[Isolation and characterization of mutactimycin-producing mutant]

Natural non-antibiotic producing Streptomyces sp. 1254 was mutagenized by UV irradiation and two active mutants were isolated. Mutant 113 produced novel anthracycline compounds designated mutactimycins. Mutactimycin A was active against the bacteriophage of Bac. subtilis and some viruses in tissue culture. The mutant 2-6 synthesized a basic water-soluble antimicrobial antibiotic. Chemical analysis of the whole cell hydrolysate and the morphological characterization showed that the strain 1254 and its mutant 2-6 were of chemotype I, belonging to the genus of Streptomyces, and the mutant 113 was of chemotype IV without mycolic acid. Co-synthesis test of strain 1254 and a blocked mutant of strain 113 gave the active compounds identical with mutactimycins. Using the actI gene as a probe, the Southern hybridization revealed homology between the actinorhodin polyketide biosynthase gene and the total DNA of the strain 1254. Based on these data it was deduced that Streptomyces sp. 1254 should have a biosynthesis pathway for mutactimycin, but some of its genes might fail in expression and mutagenesis would make the silent gene(s) active.

Long-term survival of xenogeneic pancreatic islet grafts induced by CTLA4lg

Antigen-specific T cell activation depends on T cell receptor-ligand interaction and costimulatory signals generated when accessory molecules bind to their ligands, such as CD28 to the B7 (also called BB1) molecule. A soluble fusion protein of human CTLA-4 (a protein homologous to CD28) and the immunoglobulin (lg) G1 Fc region (CTLA4lg) binds to human and murine B7 with high avidity and blocks T cell activation in vitro. CTLA4lg therapy blocked human pancreatic islet rejection in mice by directly affecting T cell recognition of B7+ antigen-presenting cells. In addition, CTLA4lg induced long-term, donor-specific tolerance, which may have applications to human organ transplantation.

Islet xenografts in fully xenogeneic (rat----mouse) chimeras: evidence for normal regulation of function in a xenogeneic mouse environment

BACKGROUND

Transplantation of untreated rat bone marrow into mouse recipients conditioned by total-body irradiation results in fully xenogeneic chimerism (rat----mouse). The chimerism is stable for up to 10 months, survival is excellent, and there is no evidence for graft-versus-host disease. We recently reported the long-term survival (greater than 180 days) of donor-specific pancreatic islet xenografts in these fully xenogeneic chimeras.

METHODS

Chimeras were prepared and typed for chimerism at 6 weeks, and diabetes was induced by streptozocin injection. Donor-specific pancreatic islets were placed under the renal capsule and recipient blood glucose levels were followed biweekly. The aim of this study was to examine whether the transplanted pancreatic islets exhibited normal function in a xenogeneic environment and assess whether the islet xenografts were not only sufficient to support euglycemia but also regulated in function in response to a glucose challenge.

RESULTS

We report for the first time that donor-specific rat islet xenografts were capable of producing normal basal and peak levels of insulin and responding to a glucose challenge in a manner similar to that of normal mouse islets.

CONCLUSIONS

These data indicate that donor-specific rat islet xenografts are functional and regulated normally in fully xenogeneic (rat----mouse) chimeras.

Evidence that the hamster tunicamycin resistance gene encodes UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase

A cDNA clone isolated from Chinese hamster ovary cells conferred elevated GlcNAc-1-P-transferase (GPT) activity and resistance to tunicamycin in transfected cells (Zhu, X., and Lehrman, M. A. (1990) J. Biol. Chem. 265, 14250-14255). It had been assumed that this cDNA, termed TRG for tunicamycin resistance gene, encoded GPT enzyme. However, other functions were not ruled out. Thus, by one of several mechanisms, the TRG protein could have instead functioned by activation of the transfected host's endogenous GPT enzyme. To analyze the biochemical function of the TRG protein, hamster TRG cDNA was stably expressed at high levels in Chinese hamster ovary cells. In addition, several antipeptide polyclonal antibodies directed against the predicted TRG protein were obtained. With these tools in hand, experiments were performed to test the hypothesis that the TRG encodes GPT enzyme, as well as to rule out other possible functions for the TRG protein. These experiments included examination of the effects of solubilization of membranes on TRG-dependent GPT activity, the apparent binding of tunicamycin to the TRG protein, and the immunoadsorption of GPT activity with TRG protein-specific antibodies. From these results, we conclude that the hamster TRG most likely encodes GPT enzyme.

Islet cell allotransplantation in diabetic patients. Histologic findings in four adults simultaneously receiving kidney or liver transplants

Refined methods of islet cell purification have led to unprecedented success of islet cell allotransplantation via portal vein infusion in diabetic patients, resulting in marked reduction of exogenous insulin requirements and recently even insulin independence. The authors report the histologic findings of islet cell allografts in the liver of four patients who had undergone combined kidney-islet or liver-islet transplantation. Islet cell clusters were detected in subcapsular location at the edge of portal triads. The early post-transplant period was characterized by patchy mixed portal infiltrates. Only minimal inflammation but decreased islet cell granulation was observed in one patient 6 months after transplantation. As histologic detection of transplanted islet cells becomes available, additional parameters for evaluation of graft survival might be defined by morphologic assessment.

The status quo, regional differences, and trend of the Chinese family structure

"Based on the 10% machine aggregate data of the fourth census of 1990 and the 1% computer sampling data, this article attempts to analyze the status quo and regional differences of China's family structure and their relationships with the level of social and economic development, and the trend of the Chinese family structure since the 1980s."