Changes of calmodulin contents in single vascular smooth muscle cells from the tail arteries of spontaneously hypertensive rats

By combining immunohistochemistry and fluorocytometry techniques, total calmodulin (total CaM), Ca(2+)-bound calmodulin (Ca.CaM) and total protein contents in single vascular smooth muscle cells (VSMC) enzymatically dispersed from the tail arteries of young (5-7 weeks old, prehypertensive) and adult (20-24 weeks old, established hypertensive) stroke-prone spontaneously hypertensive rats (SHRsp) were studied and compared with those of age-matched Wistar-Kyoto rats (WKY). No significant difference was found in total CaM, Ca.CaM and protein contents between young SHRsp and WKY. Total CaM and protein contents in adult SHRsp were increased by similar degrees (30.7% and 27.5%, respectively) as in age-matched WKY, suggesting that increased total CaM content may be a consequence of increased synthesis of cellular protein during hypertension. However, Ca.CaM contents in adult SHRsp were significantly increased over those in age-matched WKY by a much higher degree (86.2%), reflecting an abnormal Ca2+ homeostasis in single VSMCs during hypertension.

Effect of intra-vas deferens injection of gossypol-polylactic acid on fertility and spermatogenesis in rats

In order to reduce gossypol's side effects, we applied a controlled drug release system. In this system gossypol is carried on a polymer of polylactic acid which controls drug release and can also be injected into the vas deferens so that the drug can act continuously and directly on spermatogenesis. We used a single dose of gossypol-polylactic acid (0.35 mg/0.1 ml for each vas deferens) which is only 0.2% of the usual antifertility dose. Fertility tests showed that male rats became infertile 4 weeks after intravasal injection of gossypol-polylactic acid. Gross and microscopic findings in the heart, liver, kidneys and lungs revealed no evidence of pathologic change. Treated rats gained body weight as fast as did the controls. The majority of spermatozoa showed breakage of the axial fibers, indicating that gossypol had diffused into the testes. The fertility of the treated rats recovered four to eight months after treatment. Gossypol-polylactic acid injected into the vas deferens exhibited a low degree of toxic side effects and a high antifertility activity, and is therefore an important approach to decreasing the side effects while enhancing the antifertility specificity of gossypol.

Cardiovascular disease risk factors and glucose tolerance. The Wadena City Health Study

Cardiovascular risk factors were examined in 453 subjects participating in the Wadena City Health Study, a population-based study to assess the relationship between diabetes and glucose intolerance with age. Each subject was classified as either having non-insulin-dependent diabetes mellitus (NIDDM), impaired glucose tolerance (IGT), or normoglycemia, using WHO criteria. Age- and body-mass-adjusted levels of systolic and diastolic blood pressure were lowest for those with normoglycemia, intermediate for those with IGT, and highest for those with NIDDM. Age- and body-mass-adjusted levels of high-density lipoprotein cholesterol were lowest for those with NIDDM, intermediate for those with IGT, and highest for those with normoglycemia, while triglyceride levels were highest for those with NIDDM, intermediate for those with IGT, and lowest for those with normoglycemia in women but not in men. Low-density lipoprotein cholesterol levels were lowest for those with NIDDM, intermediate for those with IGT, and highest for those with normoglycemia. With the exception of men with IGT, no differences by glycemic strata were observed for plasma total cholesterol. The prevalence of smoking showed no consistent pattern by glycemic status. These findings suggest that individuals with IGT have an atherogenic risk factor pattern that may put them at greater risk for coronary heart disease than those with normoglycemia. Intervention strategies such as diet, exercise, and/or drug therapy should be tested to evaluate whether these are effective in preventing conversion to overt diabetes and normalizing cardiovascular disease risk factors.

Trends in mortality, morbidity, and risk factor levels for stroke from 1960 through 1990. The Minnesota Heart Survey

OBJECTIVE

The Minnesota Heart Survey is a population-based study designed to monitor and explain trends in cardiovascular mortality, morbidity, and risk factors.

DESIGN

Surveillance time-trends study.

METHODS

The following trends were examined among men and women aged 25 to 74 years living in Minneapolis-St Paul, Minn: (1) stroke mortality from 1960 through 1990; (2) risk factors in population-based surveys conducted in 1973 through 1974, 1980 through 1982, and 1985 through 1987; and (3) morbidity in a 50% sample of hospitalized discharges for acute-stroke in 1970, 1980, and 1985.

RESULTS

Stroke mortality in Minneapolis-St Paul declined slowly from 1960 through 1972 (average fall, 2.4% per year), dropped sharply from 1972 through 1984 (average fall, 6.5% per year), but exhibited little change thereafter (average fall, 1.5% per year). The average level of cardiovascular disease risk factors fell from 1973-1974 to 1985-1987, with the exception of body mass index. In particular, hypertension diagnosis, treatment, and control levels improved substantially between 1973-1974 and 1980-1982, although there was little improvement after 1980-1982. While discharge rates for hospital-coded acute stroke declined substantially between 1970 and 1985 in both sexes, no clear trend was observed in definite stroke rates as validated using standard clinical criteria. Twenty-eight-day case fatality rates of definite stroke improved significantly from 1970 to 1985.

CONCLUSIONS

The substantial decline in stroke mortality of more than 50% from 1960 through 1990 appears to have been attributable to both primary and secondary prevention. These data suggest that the long decline in stroke mortality and morbidity in Minneapolis-St Paul has plateaued, although improved detection of stroke with computed tomography prevents an unequivocal conclusion.

The quantitative alteration of 5s rRNA during the development of mammalian erythroid cells and its effect on DNA synthesis in SP2/0 mouse myeloma cells

Mouse myeloma cells (SP2/0) were incubated with 125I-5s rRNA from rabbit reticulocytes and processed for autoradiography. The results indicated that 5s rRNA could pass into the nuclei of mouse myeloma cells. In a separate experiment, SP2/0 were incubated with cold 5s rRNA, then with 3H-TdR and processed for autoradiography. It was found that in the mouse myeloma cells, DNA synthesis and cell division were obviously suppressed. In another series of experiments, rRNA was extracted from rabbit bone marrow, reticulocytes and erythroid cells and from rat embryonic liver and erythroid cells. The rRNA was analyzed by agarose electrophoresis. It was found that the amount of 5s rRNA in various stages of erythroid development changed along with the denucleating process. Thus it seems likely that 5s rRNA from mammalian erythroid cells could play a role in reversing the malignant phenotype of tumor cells and denucleation of mammalian erythroid cells through inhibiting DNA synthesis.

[Establishment of Wg3h-neo cell line with two genetic markers]

Plasmid PSV2-neo DNA containing neo gene (PSV2 neo) was successfully transferred into Wg3h cells, a HGPRT-Chinese hamster fibroblast cell line, by calcium phosphate DNA co-precipitating technique. Cells carrying two selectable markers (AGR and G418R) were thus obtained and passed for more than 40 generations, and designated as Wg3h-neo cell line. The existence of PSV2-neo sequences in the Wg3h-neo genome was confirmed by dot-blot hybridization with PSV2-neo DNA probe. Comparative studies showed that no significant difference in morphology, growth rate or genetic characteristics could be found between the Wg3h and Wg3h-neo cell lines.

Sodium butyrate blocks HeLa cells preferentially in early G1 phase of the cell cycle

The effects of sodium butyrate on the cell-cycle transverse of HeLa cells was re-examined using the kinetic and the premature chromosome condensation methods of cell-cycle analysis. The results of this study indicate that the sodium butyrate effects are dose-dependent and cell-cycle phase-specific. Cells in the early G1 period are the most sensitive to the inhibitory effects of the drug. When HeLa cells in exponential growth were exposed to a 5 mM concentration of butyrate for 48 h. 67% of the cell population was preferentially arrested in the early G1 period as indicated by the condensed morphology of the prematurely condensed chromosomes (PCC). There was no accumulation of cells in the G2 period. The results of this study suggest that hyperacetylation of histones induced by sodium butyrate does not necessarily result in decondensation of chromatin and the butyrate-enhanced protein, which has been reported to be present in butyrate-treated cells, may have a role in the regulation of the transition of cells from early G1 to the subsequent phases of the cells cycle.

Rapid analysis of drug effects on the cell cycle

Using a flow cytometric technique to analyse DNA content and chromatin structure simultaneously, the following parameters of cell cycle progression were estimated in control and drug-treated L1210 cell cultures: (a) the kinetics of cell exit from the G1 phase; (b) the probability of cell exit from the indeterminate portion of the G1 phase, measured as the half-time of cell residence in that state; (c) the duration of the deterministic portion of G1 phase; (d) the rates of cell transit through selected "windows" in S phase; (e) the rate of cell entrance into mitosis; (f) the mean duration of the cell cycle (Tc). These parameters are obtained in a single stathmokinetic experiment from measurements of individual samples withdrawn at 30 min-1 hr intervals from Vinblasatine-treated cultures. In the same experiment mitotic indices are obtained with high statistical accuracy, and may be used to determine the terminal point of drug action. In addition to cell cycle analysis the method makes it possible to detect drug-induced changes in nuclear chromatin that are manifested by varying sensitivity of DNA in situ to denaturation by acid. Such changes were found to be associated with defective chromatin condensation, altered histone modifications or intercalation of the drugs into DNA. Using this technique the effects of sodium n-butyrate and two new antitumor drugs on L1210 cells were investigated.