Quantitative axial oblique contrast left ventriculography: validation of the method by demonstrating improved visualization of regional wall motion and mitral valve function with accurate volume determinations

To compare the relative merits of conventional and axial RAO/LAO angiography, we performed biplane left ventricular (LV) cineangiograms in 36 patients in both the conventional 30-degree RAO/60-degree LAO projection and in the axial 45-degree RAO/60-degree LAO/25-degree cranial projection, in random sequence. LV volumes were calculated by a computerized system utilizing modification of the area-length method. Eng-diastolic volume, end-systolic volume, and ejection fraction correlated closely between the two projections (r = 0.93, 0.95, and 0.86, respectively). The axial 60-degree LAO view projected the LV apex inferiorly, the LV outflow tract superiorly, reduced LV foreshortening, and "uncovered" the LV outflow tract in all cases. Segmental wall motion abnormalities of the ventricular septum, apex, and posterior wall were better evaluated by the axial 60-degree LAO view in patients with regional asynergy in these zones. The 45-degree RAO, compared to the 30-degree RAO view, allowed a true tangential view of the mitral valve and provided a large "clear area" between the mitral valve and descending aorta, which improved the ability to quantify mitral regurgitation. Thus, axial oblique LV angiography improves evaluation of LV regional wall motion and mitral valve function without compromising LV volume quantitation.     

The pKa of the general acid/base carboxyl group of a glycosidase cycles during catalysis: a 13C-NMR study of bacillus circulans xylanase

The 20 kDa xylanase from Bacillus circulans carries out hydrolysis of xylan via a two-step mechanism involving a covalent glycosyl-enzyme intermediate. In this double-displacement reaction, Glu78 functions as a nucleophile to form the intermediate, while Glu172 acts as a general acid catalyst during glycosylation, protonating the departing aglycone, and then as a general base during deglycosylation, deprotonating the attacking water. The dual role of Glu172 places specific demands upon its ionization states and hence pKa values. 13C-NMR titrations of xylanase, labeled with [delta-13C]glutamic acid, have revealed pKa values of 4.6 and 6.7 for Glu78 and Glu172, respectively. These agree well with the apparent pKa values obtained from a study of the pH dependence of kcat/Km and demonstrate that, at the enzyme's pH optimum of 5.7, the nucleophile Glu78 is deprotonated and the general acid Glu172 initially protonated. Remarkably, the pKa for Glu172 drops to 4.2 in a trapped covalent glycosyl-enzyme intermediate, formed by reaction with 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-xylobioside [Miao et al. (1994) Biochemistry 33, 7027-7032]. A similar pKa is measured for Glu172 when a glutamine is present at position 78. This large decrease in pKa of approximately 2.5 units is consistent with the role of Glu172 as a general base catalyst in the deglycosylation step and appears to be a consequence of both reduced electrostatic repulsion due to neutralization of Glu78 and a conformational change in the protein. Such "pKa cycling" during catalysis is likely to be a common phenomenon in glycosidases.     

The prevalence and severity of cancer pain: a study of newly-diagnosed cancer patients in Taiwan

In current clinical practice the "double-stapling technique" is the standard for reanastomosis following minimally invasive sigmoid resection. In the present study, we compared the TESA technique (transient endoluminally stented anastomosis) with conventional stapled anastomosis and evaluated the effect of remnant foreign material on follow-up examination with endosonography. Laparoscopic sigmoid resection was performed in 12 pigs (mean weight 63+/-5.9 kg). Animals were randomly divided into two groups: In Group A, reanastomosis was performed following a standard technique using a 29-mm circular stapler. In Group B, the TESA technique using a resorbable radiopaque stent of polyglycolic acid was applied. The anastomosis was examined by plain x-ray on days 1, 7, and 14, and by contrast enema on day 42, respectively. Endosonography, macroscopic inspection, and histological evaluation of the anastomosis were performed on day 42. All anastomoses in group A were patent. In one animal in Group B stent displacement with subsequent leak of the anastomosis was observed. Circumferential length of the anastomosis on day 42 did not differ between the groups (Group A: 8.00+/-0.45 cm vs. Group B: 7.8+/-2.0 cm, p = 0.82). The duration of the operation was 130+/-27 minutes in Group A and 100+/-18 minutes in Group B (p = 0.06). Weight gain was equal: Group A: 24+/-9.6 kg vs. Group B: 24+/-5.0 kg, p = 0.74. Endosonography on day 42 postoperatively in the area of the anastomosis in group A was impaired due to metallic staples. TESA is a competitive method for reanastomosis following laparoscopic sigmoid resection. In contrast to the conventional technique, the anastomosis is free of foreign material 1 month after the operation, which facilitates follow-up examinations with endosonography as well as other imaging diagnostics.     

AutoCyte Interactive Screening System. Experience at a university hospital cytology laboratory

The F1-ATPase is a multimeric enzyme (alpha3 beta3 gamma delta epsilon) primarily responsible for the synthesis of ATP under aerobic conditions. The entire coding region of each of the genes was deleted separately in yeast, providing five null mutant strains. Strains with a deletion in the genes encoding alpha-, beta-, gamma- or delta-subunits were unable to grow, while the strain with a null mutation in epsilon was able to grow slowly on medium containing glycerol as the carbon source. In addition, strains with a null mutation in gamma or delta became 100% rho0/rho- and the strain with the null mutation in gamma grew much more slowly on medium containing glucose. These additional phenotypes were not observed in strains with the double mutations: Delta alpha Delta gamma, Delta beta Delta gamma, Deltaatp11 Delta gamma, Delta alpha Delta delta, Delta beta Delta delta or Deltaatp11 Delta delta. These results indicate that epsilon is not an essential component of the ATP synthase and that mutations in the genes encoding the alpha- and beta-subunits and in ATP11 are epistatic to null mutations in the genes encoding the gamma- and delta-subunits. These data suggest that the propensity to form rho0/rho- mutations in the gamma and delta null deletion mutant stains and the slow growing phenotypes of the null gamma mutant strain are due to the assembly of F1 deficient in the corresponding subunit. These results have profound implications for the physiology of normal cells.     

Strain-specific antibodies to wild poliomyelitis viruses as an index of the circulation of these viruses in a surveyed territory

This article explores the game of golf as it appears in the medical literature. Included are sections on the historical interaction of golf and medicine, the physiology and performance of golf, illness and injury related to golf, environmental concerns involving golf course management, physical disabilities, medical research and golf, and specific medical specialty references to golf.     

The problem of genetic-biochemical basis of individual sensitivity in occupational medicine

Human sensitivity to various factors of occupational environment (toxic chemicals, aerosols with mostly fibrogenic effects, etc.) depends on individual hereditary features determining adaptation or dysadaptation with subsequent disease. Studies of propensity and resistance in individuals exposed to occupational hazards should cover analysis of genetic basis for polymorphism in certain biochemical systems determining relationships between hazards detoxication and activation, DNA alteration and repair.     

Spatial electrical patterns in simulated neuronal dendrites

Steady state longitudinal distributions of (a) the density of channels conducting an inward transmembrane current of cations, (b) the submembrane concentrations of these cations, and (c) the resting membrane potential, were investigated in a phenomenological model of a cylinder-shaped dendritic process of the neuron. It was found that spatially non-uniform patterns of these distributions occur only if one of the following conditions held (i) an increase in the intracellular concentration of cations conducting an inward passive transmembrane current amplified the active efflux of those cations by the pump and attenuated their passive influx through the voltage dependent channels, with amplification of the efflux lower than attenuation of the influx; (ii) molecules of mobile channels bore a negative electrophoretic charge exposed to the intracellular space and were subject to lateral electrodiffusion in the membrane; (iii) the cations induced a further release of cations from intracellular stores. Numerical simulation studies of the membrane with Na and K channels and Na/K pumps with conditions (i) and (ii) have demonstrated the possibility of the creation of inhomogeneous patterns in the neurites. These inhomogeneous patterns are dissipative structures (DSs), and they can be spatially periodic.