Comparative structural and immunochemical properties of leghaemoglobins

Circular dichroism studies on leghaemoglobins from snake bean, lupin, serradella and other plants show that, in common with soybean (reported earlier) they have a similar overall polypeptide chain conformation and haem environment and orientation. Immunochemical studies, on the other hand, suggest that the antigenic determinants on the surface of the leghaemoglobins vary considerably. Thus, firstly the alpha-helix content of the leghaemoglobins as a class is very similar (60-65%) and approaches that of the myoglobins, secondly, the sign, magnitude and shape of their circular dichroism spectra in the near ultraviolet, Soret and visible regions suggest close similarities in the environment and orientation of a structurally important tryptophan residue and of the haem moiety, and thirdly, there is comparatively weak haem-protein interaction. The extent of immuno cross-reactivity was found to be best deomonstrated using the Farr radioimmunoassay procedure. The results were (a) 5 leghaemoglobins from one plant (soybean) crossreacted completely but with varying affinities. (b) The extent of cross reactivity between leghaemoglobins from different plants was compared to that within a single plant; the reaction of antiserum to a soybean leghaemoglobin with a serradella leghaemoglobin was weak, with a snake bean leghaemoglobin still weaker (and incomplete) while lupin leghaemoglobins showed no cross reactivity at all. (c) The "rapid" attenuation of cross reactivity among different plant leghaemoglobins is explicable in terms of the extensive amino acid substitutions which have been demonstrated in the literature and in the present studies. (d) In view of this rapid divergence it is not surprising that sperm whale and horse heart myoglobins showed no cross reactivity with soybean leghaemoglobins. In summary, amino acid substitutions in the leghaemoglobin family are conformationally but not immunochemically conservative.     

Characterization of prostaglandin production in tissue culture of rat renal medullary cells

The purpose of our studies was to examine the role of the nervous system in arrhythmias produced by digitalis overdose and coronary artery occlusion in the cat. This was done by observing the effect of these arrhythmogenic procedures on cardiac efferent neural activity and then determining whether any observed alteration in neural activity contributed to the cardiac rhythm disturbances evoked by digitalis and coronary artery occlusion. Our data indicate that both procedures used to evoke arrhythmias activate each division of the autonomic nervous system. Activation of the sympathetic nervous system resulted in a deleterious effect on cardiac rhythm whereas activation of the parasympathetic nervous system, in general, resulted in a beneficial effect on cardiac rhythm. With coronary occlusion, the role exerted by the nervous system depended on the anatomic location of the involved myocardium. Studies directed at elucidating the mechanisms whereby the nervous system caused cardiac rhythm disturbances indicated that there may be an important difference between the antiarrhythmic efficacy of beta-adrenergic blockade and bilateral stellate ganglionectomy. The latter procedure proved to be a more effective way of removing deleterious sympathetic neural effects on the heart. In conclusion, our findings suggest that the development of new drugs for treating arrhythmias resulting from digitalis and coronary occlusion should be aimed at finding drugs that act to either depress central sympathetic outflow or enhance parasympathetic effects on the ventricle.     

Effect of NaCl on textural changes and protein and lipid degradation during the ripening stage of sufu,a Chinese fermented soybean food

Sufu is made by solid state fungal fermentation (using Actinomucor elegans) of tofu, followed by salting and maturation in dressing mixtures containing salt, alcohol and various other ingredients. NaCl in dressing mixtures strongly affected the changes in textural properties and the hydrolysis of protein and lipid of sufu. Higher salt contents (14% w/w) resulted in increased hardness (+100%) and elasticity (+18%) and reduced adhesiveness (?30%). Hardness and elasticity could be used to judge the extent of sufu ripening. SDS‐PAGE showed the disappearance of all protein subunits at 80 and 110 g kg^?1 salt content; however, some protein subunits were still detectable at 140 g kg^?1 salt content after 60 days of ripening. Higher ratios of free amino nitrogen to total nitrogen (FAN/TN = 0.4–0.45) and free amino acids to crude protein (FAA/CP = 0.24–0.26) were observed in sufu with lower (80 g kg^?1) salt content. FAN/TN and FAA/CP in white sufu (obtained with dressing mixtures containing only salt and alcohol) were higher than those in red sufu (obtained with dressing mixtures containing angkak or kojic red rice) owing to different dressing mixture compositions. Increases in free fatty acids (FFA) were also observed during ripening. FFA levels in sufu with lower salt content increased rapidly during the first 30–40 days and then increased slowly, probably resulting from the formation of fatty acid esters. Lowering the salt content (80 g kg^?1) can shorten the ripening time to 40 days, which is of benefit to manufacturers. However, sufu will spoil, ie undergo souring, during the ripening stage at salt contents of 50 g kg^?1 or lower. Copyright © 2003 Society of Chemical Industry     

Time to clinical stability in patients hospitalized with community-acquired pneumonia: implications for practice guidelines

CONTEXT: Many groups have developed guidelines to shorten hospital length of stay in pneumonia in order to decrease costs, but the length of time until a patient hospitalized with pneumonia becomes clinically stable has not been established. OBJECTIVE: To describe the time to resolution of abnormalities in vital signs, ability to eat, and mental status in patients with community-acquired pneumonia and assess clinical outcomes after achieving stability. DESIGN: Prospective, multicenter, observational cohort study. SETTING: Three university and 1 community teaching hospital in Boston, Mass, Pittsburgh, Pa, and Halifax, Nova Scotia. PATIENTS: Six hundred eighty-six adults hospitalized with community-acquired pneumonia. MAIN OUTCOME MEASURES: Time to resolution of vital signs, ability to eat, mental status, hospital length of stay, and admission to an intensive care, coronary care, or telemetry unit. RESULTS: The median time to stability was 2 days for heart rate (< or =100 beats/min) and systolic blood pressure (> or =90 mm Hg), and 3 days for respiratory rate (< or =24 breaths/min), oxygen saturation (> or =90%), and temperature (< or =37.2 degrees C [99 degrees F]). The median time to overall clinical stability was 3 days for the most lenient definition of stability and 7 days for the most conservative definition. Patients with more severe cases of pneumonia at presentation took longer to reach stability. Once stability was achieved, clinical deterioration requiring intensive care, coronary care, or telemetry monitoring occurred in 1% of cases or fewer. Between 65% to 86% of patients stayed in the hospital more than 1 day after reaching stability, and fewer than 29% to 46% were converted to oral antibiotics within 1 day of stability, depending on the definition of stability. CONCLUSIONS: Our estimates of time to stability in pneumonia and explicit criteria for defining stability can provide an evidence-based estimate of optimal length of stay, and outline a clinically sensible approach to improving the efficiency of inpatient management.     

A powerful GABA(B) receptor-mediated inhibition of GABAergic neurons in the arcuate nucleus

We combined histofluorescence with in situ hybridization to identify GABAergic neurons in the arcuate nucleus (ARC) following electrophysiological recordings, using GAD65 as a marker. Intracellular recordings were made in hypothalamic slices prepared from ovariectomized guinea pigs. Over 90% of ARC neurons tested with the GABA(B) receptor agonist baclofen responded with a membrane hyperpolarization or an outward current. The hyperpolarization was dose-dependent, and the GABA(B) receptor antagonist CGP 35,348 produced a rightward shift in the agonist dose-response curve. Agonist potency was lower, and the efficacy greater, in GAD-positive neurons. The use of this novel technique for identifying GABAergic neurons thus reveals differences in the pharmacodynamics of GABA(B) receptor activation GABAergic and non-GABAergic ARC neurons.     

Classifying meconium-stained liquor: is it feasible?

Four samples each of clear and lightly (thin), moderately, and heavily (thick) meconium-stained amniotic fluid were divided in two portions and submitted twice for assessment to 20 midwives (a total of 320 case assessments). None of the midwives completely agreed with the standard assessment for more than 85 percent of the cases. When disregarding clear samples, for which there was good agreement, each of the midwives classified on average only 35.8 percent of the meconium-stained samples in the same category on each of the four occasions that they were presented to them. Calculation of kappa statistics, which express proportional agreement corrected for chance, indicated that none of the midwives showed very good agreement (kappa > 0.81) with the standard and that fewer than 10 percent showed very good agreement with themselves. The data indicate that grading the severity of meconium staining by visual assessment has such poor accuracy and precision that it cannot provide a valid basis for assigning different care policies to different degrees of meconium staining.     

Cholinergic blockade and the mesenteric artery response to head-up tilt-induced central hypovolaemia

The methylation of phosphatidylethanolamine is an auxiliary pathway for phosphatidylcholine biosynthesis in liver. Two forms of the enzyme, phosphatidylethanolamine N-methyltransferase, which catalyses this reaction, are located on the endoplasmic reticulum and mitochondria-associated membranes. Both forms are encoded by a single murine gene, Pempt, located on chromosome 11. The expression of the gene begins at birth. An inverse relationship exists between the rate of liver growth and the expression of phosphatidylethanolamine N-methyltransferase. However, disruption of the Pempt gene does not alter liver growth in mice or cause any other obvious phenotype.