Lovastatin decreases de novo cholesterol synthesis and LDL Apo B-100 production rates in combined-hyperlipidemic males

The effect of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, on the kinetics of de novo cholesterol synthesis and apolipoprotein (apo) B in very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) was investigated in five male patients with combined hyperlipidemia. Subjects were counseled to follow a Step 2 diet and were treated with lovastatin and placebo in randomly assigned order for 6-week periods. At the end of each experimental period, subjects were given deuterium oxide orally and de novo cholesterol synthesis was assessed from deuterium incorporation into cholesterol and expressed as fractional synthesis rate (C-FSR) and production rate (C-PR). Simultaneously, the kinetics of VLDL, IDL, and LDL apo B-100 were studied in the fed state using a primed-constant infusion of deuterated leucine to measure fractional catabolic rates (FCR) and production rates (PR). Drug treatment resulted in significant decreases in total cholesterol (-29%), VLDL cholesterol (-40%), LDL cholesterol (-27%), and apo B (-16%) levels and increases in HDL cholesterol (+13%) and apolipoprotein (apo) A-I (+11%) levels. Associated with these plasma lipoprotein responses was a significant reduction in both de novo C-FSR (-40%; P = .04) and C-PR (-42%; P = .03). Treatment with lovastain in these patients had no significant effect on the FCR of apoB-100 in VLDL, IDL, or LDL, but resulted in a significant decrease in the PR of apoB-100 in IDL and LDL. Comparing the kinetic data of these patients with those of 10 normolipidemic control subjects indicates that lovastatin treatment normalized apoB-100 IDL and LDL PR. The results of these studies suggest that the declines in plasma lipid levels observed after treatment of combined hyperlipidemic patients with lovastatin are attributable to reductions in the C-FSR and C-PR of de novo cholesterol synthesis and the PR of apoB-100 containing lipoproteins. The decline in de novo cholesterol synthesis, rather than an increase in direct uptake of VLDL and IDL, may have contributed to the decline in the PR observed.     

Physical properties of ceramides: effect of fatty acid hydroxylation

The structural and thermotropic properties of alpha-hydroxy fatty acid (HFA) and non-hydroxy fatty acid (NFA) ceramides (CER) have been studied using differential scanning calorimetry (DSC) and X-ray diffraction techniques. The DSC of anhydrous HFA-CER shows a single, sharp reversible transition at 95.6 degrees C (delta H = 15.3 kcal/mol). At intermediate hydrations HFA-CER exhibited more complex behavior but at maximum hydration only a single reversible transition is observed at 80.0 degrees C (delta H = 8.5 kcal/mol). X-ray diffraction of hydrated (74% water) HFA-CER at 20 degrees C shows a lamellar structure with a bilayer periodicity d = 60.7 Angstrum; a single wide angle reflection at 4.2 Angstrum is characteristic of hexagonal chain packing. Above the main transition temperature at 91 degrees C, a hexagonal (HII) phase is observed. In contrast, DSC of anhydrous NFA-CER demonstrates two thermal transitions at 81.3 degrees C (delta H = 6.8 kcal/mol) and 85.9 degrees C (delta H = 3.5 kcal/mol). With increasing hydration, both transitions shift towards lower temperatures; at maximum hydration, on heating, the endothermic transitions occur at 72.7 degrees C (delta H = 9.8 kcal/mol) and 81.1 degrees C (delta H = 4.0 kcal/mol). On cooling, there is hysteresis of both transitions. X-ray diffraction of NFA-CER (80% water) at 20 degrees C shows a well-ordered lamellar structure with a bilayer periodicity d = 58.6 Angstrum and three wide-angle reflections at 4.6 Angstrum, 4.2 Angstrum, and 3.8 Angstrum. At 77 degrees C (between the two transitions), again a lamellar structure exists with reduced bilayer periodicity d = 53.1 Angstrum and four wide-angle reflections at 4.6 Angstrum, 4.2 Angstrum, and 3.8 Angstrum are observed. Above the second transition, only a single low angle reflection at 30.0 Angstrum is observed; a diffuse reflection at 4.6 Angstrum is indicative of a melted chain phase. Thus, HFA-CER exhibits a simple phase behavior involving the reversible conversion of a gel phase to a hexagonal phase (L beta-->HII). However, NFA-CER shows a more complex polymorphic phase behavior involving two gel phases.     

Inhibition of murine renal carcinoma pulmonary metastases by systemic administration of interferon gamma: mechanism of action and potential for combination with interleukin 4

We have previously demonstrated that IFN-gamma causes cell growth inhibition and up-regulation of MHC antigens in human renal cell carcinoma cell lines. In this study, we have investigated the therapeutic potential of IFN-gamma for the treatment of 5-day established pulmonary metastases induced by i.v. injection of Renca cells, a murine renal adenocarcinoma. We found that systemic injections of IFN-gamma significantly reduced the number of lung metastases in a dose-dependent manner and increased mouse survival. Histological evaluation of IFN-gamma-treated lungs showed residual small tumor nodules containing extensive necrosis and mononuclear infiltrates. Immunohistochemistry studies on lung sections showed macrophage infiltration into tumor nodules, and in vivo depletion of macrophages partially inhibited IFN-gamma antitumor effect, suggesting a role for the macrophages in tumor destruction. Lymphocyte depletion of either natural killer (NK) cells or CD4+ or CD8+ T-cell subsets or both T-cell subsets did not affect the IFN-gamma effect, whereas depletion of both NK and T cells decreased the antitumor activity of IFN-gamma. These data indicate that neither T cells nor NK cells are essential for this activity but that either lymphocyte population can contribute to the IFN-gamma effect. An optimal dose of IFN-gamma inhibited by 60% the growth of Renca cells treated for 3 days in vitro, but this effect was transient and less pronounced in a long-term colony assay, suggesting that IFN-gamma direct growth inhibition may play a role but may not be sufficient to mediate its antitumor effect in vivo. In vitro, IFN-gamma caused up-regulation of class I MHC antigens and induction of class II antigen expression in Renca cells, an effect that may enhance Renca immunogenicity but may be relevant only when a T-cell response is elicited. A sequential administration of IFN-gamma followed by interleukin 4 was therapeutically better than IFN-gamma alone for the treatment of advanced pulmonary metastases, probably due to different antitumor mechanisms induced by these two cytokines.     

A prospective study of the effect of fundoplication on primary and secondary peristalsis in the esophagus

BACKGROUND: Delay of prenatal care is an important risk for poor birth outcome, yet its association with maternal knowledge and beliefs remains insufficiently studied. This research examined the relationship of unintended childbearing and beliefs about the importance of prenatal care with initiation after the first trimester, adjusting for key sociodemographic determinants. METHODS: One hundred fifty-four Texas hospitals accounting for 80 percent of state births were asked to collect surveys from all women delivering infants during a one-week interval in 1986. Seventy-four percent of hospitals and 70 percent of women participated (n = 2032). No differences occurred between the sample and the population on rates of delayed care and low birthweight or maternal demographics. RESULTS: Since delayed prenatal care is more frequent among low-income women, analyses were limited to those below the 200 percent poverty level. After adjustment for maternal age, marital status, education, parity, race, and health insurance status employing logistic regression, unintended births were 1.6 times more likely to involve delayed care. Mothers who believed prenatal care was unimportant were 2.1 times more likely to delay care. These coefficients exceeded or about equaled those for the covariates. CONCLUSIONS: Preconception education about the value of prenatal care and family planning programs to prevent unintended pregnancies should be conducted together with efforts to overcome financial and structural barriers if progress toward national prenatal care objectives is to be achieved.     

In situ measurement of lithium mass transfer during charging and discharging of a Ni–Sn alloy electrode

The charging (lithiation) and discharging (delithiation) of a Ni–Sn alloy electrode was examined by means of holographic interferometry and laser scanning confocal microscopy (LSCM). The developing concentration profile of Li⁺ ion during discharging (delithiation) of the Ni–Sn alloy electrode agreed reasonably well with the prediction based on transient diffusion theory, indicating that the cell configuration successfully suppressed natural convection due to the electrochemical reaction. The morphological variation of Ni–Sn alloy electrode during charge/discharge cycle could be observed very clearly by in situ LSCM. It was found that the contraction of active material during the discharge (delithiation) initiates cracks in the Ni–Sn alloy electrode.