Reversibility of acute alcohol cardiac depression: 31P NMR in hamsters

Isolated hamster hearts were perfused with 2% ethanol for 30 min and then reequilibrated with control medium. One group of hamsters was pretreated with verapamil. Another group received diltiazem. Myocardial verapamil levels were 9.5 +/- 0.7 mg/g dry wt; diltiazem levels were 22 +/- 7 mg/g dry wt. Energy metabolites were assessed by using 31P NMR standardized with high-pressure liquid chromatography of freeze-clamped tissue. Intracellular calcium was measured by atomic absorption spectrophotometry, marking the extracellular space with K(CoEDTA). After 30 min of perfusion, untreated hamster hearts showed a 74% decrease in developed pressure, a marked increase in end-diastolic pressure, a decrease of ATP from 9.8 to 8.8 mmol, and an increase of Pi from 6.7 to 9.8 mmol, but no change of phosphocreatine (PCr) or intracellular pH (pHi). Verapamil pretreatment partially prevented cardiac depression during alcohol perfusion. Whereas diltiazem had no protective effect. After reequilibration, developed pressure and oxygen consumption significantly exceeded control values. ATP decreased to 8 mmol; pHi, PCr, and Pi showed no significant change. Verapamil-pretreated hearts showed better performance than untreated hearts without change in PCr and Pi, whereas ATP dropped slightly to 8.7 mmol. Thus, functional cardiac depression resulting from acute alcohol exposure is reversible. Increased intracellular calcium levels during alcohol exposure normalized after the removal of alcohol. There was no major change in high-energy phosphates during alcohol exposure or after the removal of alcohol. Verapamil protects the heart from functional depression during alcohol exposure without affecting energy resources.

Chemomechanics of altered perfusion pressure in rat hearts

In an apex-ejecting isolated perfused working rat heart, as well as isovolumic preparations of rat hearts, perfusion pressure was studied independent of afterload. A decrease in perfusion pressure caused an immediate decrease in developed pressure (10s). There was a significant increase in free Pi and the phosphorylation potential after 20-30 min of perfusion at a reduced coronary flow induced by a reduction in perfusion pressure. Developed pressure decreased prior to the phosphorylation potential and inorganic phosphate; however, the phosphorylation set a limit to maximum work performance. At a perfusion pressure of 140 cm H2O and an afterload of 140 cm H2O, work imposed on the heart was maximum; there was no further increase in work.

Effects of altered coronary perfusion pressure on function and metabolism of normal and cardiomyopathic hamster hearts

The effects of a sudden decrease in coronary perfusion pressure from 140 to 0 cmH2O for a 10-second interval were analyzed in normal and cardiomyopathic hamster hearts to determine whether cardiomyopathy would affect the relationship between altered coronary perfusion pressure and left ventricular geometry, wall thickness, myocardial hydrodynamics, and hemodynamics. In normal hamsters, an acute reduction in coronary perfusion pressure resulted in a decrease in left ventricular short axis epicardial cross-sectional area, base to apex length, diastolic wall thickness, myocardial water content and developed pressure. In cardiomyopathic hamsters all results induced by lowering the hydrostatic pressure of the perfusing medium were the same except that diastolic wall thickness failed to decline, indicating a decrease in intramyocardial elasticity in dilated cardiomyopathy. In parallel studies, hearts were freeze clamped at end-diastole and high energy phosphates and energy metabolites analyzed. In both normal and cardiomyopathic hamsters no significant changes were observed in ATP, PCr, or Pi levels at 10 s following the decrease in perfusion pressure. However, during the abrupt decrease in coronary perfusion pressure adenosine increased and cAMP decreased in both groups of animals. The erectile effect of altered coronary perfusion pressure is partially attenuated in the cardiomyopathic hamster in which no change in diastolic wall thickness occurs during an abrupt change in the hydrodynamics of the heart.

Influence of heart rate on metabolic and hemodynamic parameters in the Syrian hamster cardiomyopathy

The effect of varying heart rate in 155- to 170-day-old isolated, perfused cardiomyopathic Syrian hamster hearts was evaluated by 31P nuclear magnetic resonance spectroscopy. At a low paced heart rate of 170 bpm, cardiomyopathic hearts did not differ from normal hearts except for a lower developed left ventricular pressure. As pacing rate was increased progressively to 270/min, cardiomyopathic hearts showed prolongation of contraction, which led to a pronounced rise in diastolic pressure as the interstimulus interval shortened. This was accompanied by a marked decrease in energy-rich phosphorus compounds. By contrast, increasing heart rate in normal hearts did not change left ventricular pressure and caused only a mild reduction in energy-rich phosphorus compounds. Intracellular pH of cardiomyopathic animals paced at 270 bpm was significantly lower than in normal animals. Thus, indices reflecting mitochondrial function of 155- to 170-day-old cardiomyopathic hamsters appear adequate at low heart rate. Increasing the heart rate unmasks latent mitochondrial dysfunction.

Cytogenetic analysis in workers occupationally exposed to nickel carbonyl

Chromosomal aberration and sister-chromatid exchange (SCE) base-line frequencies and SCE frequencies induced by 10 ng/ml mitomycin C (MMC) were analysed in cultured peripheral lymphocytes of 65 workers occupationally exposed to nickel carbonyl Ni(CO)4. The subjects were divided into 4 groups: (1) control; (2) exposed to nickel carbonyl (= exposed); (3) cigarette smokers; (4) smoking-exposed. The results show that there are no significant differences in chromosomal aberration frequencies, breaks or gaps, between the various groups. However, the SCE base-line frequency of the smoking-exposed group, with an average of 7.7/cell, was significantly higher than that of the control group, with an average of 6.5/cell (P less than 0.01), and also than that of the exposed group with an average of 5.9/cell (P less than 0.01). Similarly, the SCE frequency induced by 10 ng/ml MMC in the smoking-exposed group which averaged 15.5/cell was significantly higher than that of the control group (average of 13.2/cell (P less than 0.05], and also than that of the exposed group with an average of 12.3/cell (P less than 0.01). Under our experimental conditions, it may be that the level of exposure was not high enough to elicit an increase in chromosomal aberrations and SCE frequencies in the non-smoker exposed group. The fact that an increase in SCE frequencies was only found in the smoking-exposed group implies that the two factors, smoking and exposure to nickel carbonyl, are jointly responsible for the result.

Protein analysis of HLA-DR2.3 haplotype

The human major histocompatibility antigens (HLA-DR, HLA-DQ, and HLA-DP), consisting of alpha and beta chains, show extensive polymorphism. Based on differences of T-cell responses, the serologically defined DR2 specificity has been divided into Dw2, Dw12, and several putative additional "Dw subtype" specificities (AZH, FJO, and MN2, which we shall designate as "DR2.3", and LD-5a). To investigate the relationships of these specificities, DR and DQ molecules were analyzed by two-dimensional gel electrophoresis (2D-PAGE). The 2D-PAGE patterns of the DR molecules are identical among DR2.3 cells. Three DR beta chain polypeptides are expressed on DR2.3 cells. The electrophoretic mobilities of two of these beta chains are different from those of beta chains from the Dw2 and Dw12 cells. The DR molecules of the LD-5a cells show similar 2D-PAGE patterns with those of DR2.3 cells. The 2D-PAGE patterns of DQ molecules are identical among DR2.3 cells. The electrophoretic mobilities of DQ beta chains are different for Dw2, Dw12, LD-5a, and DR2.3 cells. These results indicate that the AZH, FJO, and MN2 cells have identical or very similar DR and DQ molecules and constitute a third, and relatively homogeneous, subgroup ("DR2.3") of the DR2 specificity. In addition, DR2.3 cells have a unique characteristic in that they express three DR beta chains.

The preventive effect of verapamil on ethanol-induced cardiac depression: phosphorus-31 nuclear magnetic resonance and high-pressure liquid chromatographic studies of hamsters

Alcoholic depression of left ventricular function was produced in normal hamsters by the administration of increasing concentrations of alcohol in drinking water (up to 50%) for 6 months. The result was assessed by phosphorus-31 nuclear magnetic resonance of isolated perfused hearts and high-pressure liquid chromatography of freeze-clamped tissues. Hemodynamic data and myocardial oxygen consumption were also monitored. Alcoholic hamsters had significantly higher inorganic phosphate and lower ATP levels, while maintaining normal intracellular pH, phosphocreatine, and creatine. Although coronary flow and oxygen consumption were maintained at normal levels, hamsters ingesting 50% ethanol had significantly lower left ventricular developed pressure and dP/dt. Treatment with verapamil during long-term ethanol consumption prevented the development of these metabolic and functional abnormalities. It is hypothesized that alcohol produces membrane abnormalities leading to adverse ion flux, and that these are largely prevented by concurrent administration of verapamil.

The three-dimensional structure of trichosanthin molecule

A model completed recently of two trichosanthin molecules in an asymmetric unit belonging to the monoclinic system is reported. It can be seen that the molecular structure consists of two domains, one large and one small, and that there are some features in the secondary structure. The dissimilarity between two molecules as well as their interactions in an independent unit correlated in a non-symmetric way has been described, moreover, the binding sites of the heavyatom position in the derivatives are also discussed.

Polymorphism of human Ia antigens generated by reciprocal intergenic exchange between two DR beta loci

Class II molecules encoded by the human major histocompatibility complex (MHC) are involved in regulating T-cell response to antigens. The mechanisms for generating polymorphism in products of the MHC have been studied extensively for both the murine H-2 and the human HLA complex. Such studies indicate that point mutations plus selection have a major role in the generation of polymorphisms of class I and class II MHC genes. However, a non-reciprocal gene conversion mechanism has been proposed to explain several examples of clustered sequence variation in MHC genes. In all these examples, the proposed gene conversion event is unidirectional; that is, one of the two interacting genes acts as sequence donor and the other as sequence recipient. No examples of potential reciprocal genetic exchange (as occurs in the fungal system), in which the two interacting genes act as both donor and recipient of gene fragments, have been found in the MHC system or in other multigene families of higher organisms. We sequenced two different HLA-DR beta complementary DNAs from each of two different cells all expressing the same serologically defined determinant (DR2) but different T-cell-recognized (Dw) specificities (Dw12 and MN2). Sequence comparisons of these four cDNA clones (and two DR beta amino-acid sequences from the DR2-Dw2 subtype) suggest that new coding sequences for DR beta molecules in the DR2 haplotypes are potentially generated by reciprocal intergenic exchange.

Ileal hyperplastic response to starvation in the rat

The ability to respond to changes in the external and internal environments is a fundamental characteristic of intestinal structure and function. We compared the responses of the rat proximal and distal small intestine to the stresses of fasting and refeeding in the rat. In the duodenum, 3 days of starvation caused villus and crypt hypoplasia, reduced incorporation of [3H]thymidine into crypt cells, decreased cell migration rate on the villus, and lowered specific and total activities of several cellular enzymes. These changes were reversed by 1 day of refeeding. In contrast, mucosal hypoplasia did not occur in the ileum during fasting, and the specific activities of the disaccharidases were increased after 3 days of starvation. However, ileal [3H]thymidine incorporation, thymidine kinase activity, and ornithine decarboxylase activity decreased during starvation. These effects were also reversed by refeeding. The results of these studies illustrate differing responses for the proximal and distal small intestine and suggest the presence of distinctly differing mechanisms for the control of their mucosal mass and enzyme activities.

Corticosteroid therapy in Epstein-Barr virus infection. Effect on lymphocyte class, subset, and response to early antigen

Corticosteroid treatment of impending upper airway obstruction due to Epstein-Barr virus (EBV) infectious mononucleosis did not alter the pattern of lymphocyte changes induced by this viral infection during the first two weeks following administration of prednisone. By 12 weeks, 11 treated students had significantly fewer lymphocytes, including B, total T, helper, and T-suppressor cell numbers, than 11 untreated EBV-infected students, and values were closer to those noted in uninfected controls. Corticosteroid therapy did not alter the serologic response to early antigens of EBV. Fever and lymphadenopathy resolved somewhat more quickly in treated students.

Syngeneic responses by murine thymocytes: a role for non-MHC and non-MLS genes

A subpopulation of thymocytes from adult mice that is nonadherent to macrophage monolayers showed dramatically increased syngeneic mixed leukocyte responses (SMLR). Cloned cells were derived by limiting dilution from these SMLR-primed BALB/c thymocytes and were maintained and subcloned by repeated stimulation with syngeneic BALB/c spleen cells without the addition of exogenous interleukins. The cloned thymocytes were tested for their reactivities against H-2- and Mls-identical BALB/c and B10.D2 spleen cells (H-2d, Mlsb). We found that BALB/c and B10.D2 stimulator cells differed significantly in their capacity to restimulate the cloned BALB/c thymocytes. In addition, polyclonal syngeneic mixed leukocyte cultures (SMLC) of BALB/c thymocytes also showed differential restimulation by BALB/c and B10.D2 stimulators. Taken together, our data indicate a role for the product(s) specified by non-MHC and non-Mls gene(s) in the autorecognition by thymocytes.

Syngeneic responses by murine thymocytes: a role for non-MHC and non-MLS genes

A subpopulation of thymocytes from adult mice that is nonadherent to macrophage monolayers showed dramatically increased syngeneic mixed leukocyte responses (SMLR). Cloned cells were derived by limiting dilution from these SMLR-primed BALB/c thymocytes and were maintained and subcloned by repeated stimulation with syngeneic BALB/c spleen cells without the addition of exogenous interleukins. The cloned thymocytes were tested for their reactivities against H-2- and Mls-identical BALB/c and B10.D2 spleen cells (H-2d, Mlsb). We found that BALB/c and B10.D2 stimulator cells differed significantly in their capacity to restimulate the cloned BALB/c thymocytes. In addition, polyclonal syngeneic mixed leukocyte cultures (SMLC) of BALB/c thymocytes also showed differential restimulation by BALB/c and B10.D2 stimulators. Taken together, our data indicate a role for the product(s) specified by non-MHC and non-Mls gene(s) in the autorecognition by thymocytes.

Studies on derivatives of 2,3-dihydro-4H-1,3,2-benzoxazaphosphorine. Synthesis and structure analysis of 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-one -(thio ne)-2-sulfide(oxide)

A series of novel organocyclophosphorus compounds including twenty-three 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-one-2 -sulfide (compounds I) and three 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-th ion e-2-oxide (compounds II) have been synthesized. Their structures were determined by IR, UV, 1HNMR, X-ray diffraction and elemental analysis. Each of compounds I showed a strong absorption between 1290-1319 cm-1 in the IR spectrum. Comprehensive studies of the spectral data and experimental results indicated that this strong characteristic absorption is different from that of the P = O linkage and thus could be considered as a result of the stretching vibration of (unsaturated C)-N single bond. In the course of synthesis of the compounds, an abnormal product (Formula: see text) is frequently formed as an isomer of the expected product I (Formula: see text). However, by suitable choice of condensation conditions, either of the isomers could be made predominantly in yield and be readily isolated from the other by recrystallizing for several times from appropriate solvent. Data for the melting point, IR, UV and 1HNMR spectra of three pairs of the isomers are given, and primary analyses of the spectra are made as well.