Showing papers by "Howard Hughes Medical Institute published in 1971"
TL;DR: Scanning electron micrographs of the endothelium of the pulmonary artery reveal that the entire surface is covered by a meshwork of irregular projections which vastly increase the surface area.
Abstract: Scanning electron micrographs of the endothelium of the pulmonary artery reveal that the entire surface is covered by a meshwork of irregular projections which vastly increase the surface area. The size and density of the projections suggest that they may function to direct an eddying flow of plasma along the endothelial surface.
97 citations
TL;DR: The enzymic activities of Pseudomonas testosteroni after growth on vanillate are investigated and find that both 3and 4-methoxybenzoates are demethylated.
44 citations
TL;DR: Rat chloroma, a tumor composed of immature granulocytes and having many similarities to human myelocytic leukemia, was found to have a fairly efficient dephosphorylating system for glycogen phosphorylase, however, the present study shows that the deph phosphatelation process in chloroma glycogen synthetase under similar conditions was negligible except when Mg’+ is added.
19 citations
TL;DR: Using an electron-dense marker, an attempt has been made to determine the origin of the small vesicles which occur in neurosecretory axons and to throw some light on the dynamics of the release process.
Abstract: The release of neurosecretory products from terminals in the corpus cardiacum has been described in a few insect species (Scharrer 1963, 1968; Johnson 1966; Bowers & Johnson 1966; Normann 1965; Smith & Smith 1966; Smith 1970). Exocytosis has been suggested as the mechanism of release in Calliphora erythrocephala (Normann 1965, 1969) and in Carausius morosus (Smith & Smith 1966; Smith 1970), whereas fragmentation into ‘synaptoid’ regions has been indicated in Periplaneta americana (Scharrer 1963, 1968) and in Myzus persicae (Johnson 1966; Bowers & Johnson 1966). It is clear that structures representing both these features exist and differences in interpretation may depend on the sequence of events contributing to release. Using an electron-dense marker, an attempt has been made to determine the origin of the small vesicles which occur in neurosecretory axons and to throw some light on the dynamics of the release process.
16 citations
TL;DR: It is shown that it is the intercalation of the drug in DNA that causes the chromosomal damage3–6 and abnormalities in human offspring7 that have been associated with LSD and that LSD has any effect on DNA conformation.
Abstract: REPORTS on the fluorescence-sensitive binding of d-LSD (d-lysergic acid diethylamide), 1-LSD and their 2-bromo derivatives to calf thymus DNA1, and on changes induced in DNA circular dichroism by LDS-25 (ref. 2), have led to the belief that it is the intercalation of the drug in DNA that causes the chromosomal damage3–6 and abnormalities in human offspring7 that have been associated with LSD. Our studies of circular dichroism, however, have failed to show that LSD has any effect on DNA conformation.
13 citations
TL;DR: Results indicate that transformation from dimer to tetramer in the presence of 0.2 M sodium fluoride and 0.04 M 2-mercapto-ethanol is influenced by 5′-AMP, and complete tetramerization of the enzyme with 5 × 10−3 M AMP was not possible.
12 citations
TL;DR: Photocatalyzed autoxidation of MbO 2 →MMB in frozen extracts of bovine muscle was found to obey first order kineticsas found for MbO2 of sperm-whale and horse.
Abstract: 1. 1. Photocatalyzed autoxidation of MbO 2 →MMB in frozen extracts of bovine muscle was found to obey first order kineticsas found for MbO 2 of sperm-whale and horse. Formation of MMb-OH in crystallized beef MMb was studied. Its pK of ionization 8·90 is closely similar to that of sperm-whale and horse and differs from that of camel (8·53). 2. 2. Among the unbound elements examined in beef muscle extracts, iron is most responsible for photo-oxidation of MbO 2 . 3. 3. EDTA+iron caused further increase in oxidation. EDTA alone however, caused protection. 4. 4. Addition of ashed diffusates to beef extracts caused complete inhibition of MMb and resulted in a red pigment with absorption maxima at 580, 542 and 412 nm. 5. 5. A metmyoglobin cationic reducing agent was isolated from deproteinized horse and bovine muscle extracts by ion-exchange chromatography.
8 citations
TL;DR: The biphasic curve has been confirmed in a hemoglobin SC patient, under physiologic conditions, suggesting that there is a differential binding of 2,3-DPG to S and non-S hemoglobin in cells of heterozygote sickle cell hemoglobinopathies.
5 citations
TL;DR: Acidification of bovine pseudoglobulin followed by neutralization leads to a “spontaneous” release of bradykinin-like activity, which has relatively large effects on arterial blood pressure and small effects on intestinal smooth muscle when compared to brady Kinin.
4 citations
01 Apr 1971
TL;DR: Application of the equilibrium method to human hemoglobin gives a value of K′ α = 5 × 10−6 for dissociation of oxyhemoglobin at pH 7.0 in 0.1 M buffer.
Abstract: An equilibrium method for determining macromolecular association by gel permeation is described. A thermodynamic description of the simplest case, dimerization, is presented in terms of the equilibrium constant for association, and equilibrium partition coefficients for species present. The theoretical analysis yields an equation relating the equivalents of monomer in the external phase to total equivalents, from which the equilibrium constant for association may be obtained. Those parameters critical in experimental design, gel swelling time, and centrifugal collapse point are determined for Sephadex gels of porosity G-25 to G-200. Application of the method to human hemoglobin gives a value of K′ α = 5 × 10−6 for dissociation of oxyhemoglobin at pH 7.0 in 0.1 M buffer.
2 citations
TL;DR: There is no real evidence that these therapeutic programs can inhibit or reverse atherosclerosis, and there is conflicting statistical evidence regarding whether mortality is changed by treatment.
Abstract: Publisher Summary This chapter discusses the interrelationship between carbohydrates and lipid abnormalities. There are two types of lipid abnormalities: (1) type II lipoprotein abnormality and (2) type IV lipoprotein abnormality. The type II lipoprotein abnormality with hypercholesterolemia can be treated with a number of measures with varying success. For this type of abnormality, the dietary measures include a low cholesterol, low animal fat diet with the addition of unsaturated fats and oils, and the drug therapy includes nicotinic acid, cholestyramine, β-sitosterol, neomycin, d-thyroxine, and clofibrate. The type IV lipoprotein abnormality with hypertriglyceridemia is known to be carbohydrate-induced. Thus, a low-carbohydrate diet—diabetic, weight-reduction type—is appropriate for this type of abnormality. Clofibrate can serve as a useful adjunct to such a diet and helps lower the triglyceride levels toward normal in such patients. However, at present, there is no real evidence that these therapeutic programs can inhibit or reverse atherosclerosis. In fact, there is conflicting statistical evidence regarding whether mortality is changed by treatment.