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Biomedical subjects

A Ray

Publications and source records attributed to A Ray.

At least 307 records · Page 17Linked to original sources
PubMed1981

Changes in myocardial pyrimidine nucleotide levels following repeated injections of isoproterenol in rats.

Changes which might lead to the initiation of cardiac hypertrophy include possible variations in the dynamics of nucleotides. In the experiments reported in this paper, changes in the pool sizes of adenine, uracil and cytosine nucleotides were observed during the initial phase of cardiac overload. Repeated subcutaneous injections of isoproterenol (ISO) (5 mg . kg-1 body weight, s.c.) were performed so as to produce symmetric cardiomegaly in rats. Under these conditions, the dry weight of the heart, on the fifth day of dialy injections of ISO, had increased by 43% and the RNA concentration by 39%. There was no significant change in the DNA concentration. No further changes in weight or in DNA and RNA concentrations were recorded from the fifth to the tenth day of treatment. Changes in UTP and ATP were carefully monitored during the first days following ISO application. The levels of both nucleotides decreased sharply at first. The ATP level remained below the control value for at least 48 h while the UTP level was rapidly restored and a further increase occurred resulting in a maximal enlargement of 82% after the 12th h. At the same time, the uracil nucleotide pool and the cytosine nucleotide pool had increased by 76% and 101%, respectively, while the adenine nucleotide content of the myocardium remained 15% below control level. Repeated injections of ISO induced effects on ATP and UTP levels which were similar in direction but attenuated. The significance of an increase in the pyrimidine nucleotide pools in relation to nucleic acid synthesis is discussed.

Adenine Nucleotides↗
PubMed1980

Cloning the gene for ribonuclease E, an RNA processing enzyme.

A transducing bacteriophage lambda Ch25rne+, which codes for ribonuclease E of E. coli, has been isolated. To achieve this a random library of Escherichia coli HindIII fragments was cloned in the lambda Charon 25 vector (prepared in F.R. Blattner's laboratory), and lambda Ch25rne+ was selected by its ability upon lysogenization to enable a temperature-sensitive (ts) rne-3071 mutant to grow and to exhibit normal RNA processing at the nonpermissive temperature of 45 degrees C. The level of RNase E was doubled in an rne+ strain lysogenized with lambda Ch25rne+. lambda Ch25rne+ directs the synthesis of a polypeptide of 71 000 m.wt., which is the size of RNase E. Restriction analysis and electron micrography of heteroduplexes suggested that the size of the host DNA insert is about 1.9 kb.

Bacteriophage lambda↗
PubMed1980

Histological study on the retrocerebral-endocrine complex with special reference to neurohaemal involvement of aorta and pericardial cells in Coccinella septempunctata (L.) (Coccinellidae-Coleoptera).

About nine median neurosecretory cells (NSC) are situated in the antero-dorsal position on either side of the pars intercerebralis of the brain. No lateral NSC could be detected. The axonic bundles, after their decussation, emerge out of the brain in the form of a single nervi corporis cardiaci (NCC) on either side. These soon undergo a dichotomy--one set of nerve fibers enter the lobulated corpus cardiacum (CC) and the other set ramify over the surface of the aorta and sends out distinct branches to the individual large, oval-shaped, pericardial cells all along the length of the aorta. Presence of neurosecretory material (NSM) could be demonstrated both in aortal wall as well as along the nerve branches that innervate the pericardial cells. Traces of NSM could be detected within the cytoplasm of the pericardial cells. While the involvement of aorta and pericardial cells, as an additional neurohaemal organs was well documented for several species of Hemiptera, the present report for Coleoptera seems to be new and of considerable interest. Thus it would seem that the role of the aorta and pericardial cells as accessory neurohaemal organ is perhaps of wider occurrence than was hitherto believed. The irregularly lobulated CC contains copious amounts of thick clumps of NSM which, by and large, tends to show a peripheral distribution. Few intrinsic secretory cells are noticeable. The CC, at its postero-lateral border forms a cap- or hood-like projection that partially overlaps the corpus allatum (CA) below. At the mesial border, the CC sends out a lobe which seems to fuse with the aortal wall. The shape of CA shows individual variation. In some, it is oval while in others it is spherical, but always with a well defined outline. No allatal nerve is demonstrable. Instead, the CA is broadly connected with the hood region of the CC. AF-positive material is also detectable in the CA, which also tends to be peripherilly distributed.

Animals↗
PubMed1980

Histological studies on the neuroendocrine organs and retrocerebal complex of Crynodes peregrinus Fuessly (Chrysomelidae-Coleopt.).

The neuroendocrine system of Crynodes peregrinus has been described by using Alkehyde-Fuchsin technique (AF) on whole amounts and sections. Four groups of neurosecretory cells are present in the brain--including the two median groups with 18-20 cells each and two lateral groups with four cells each. The neurosecretory material (NSM) reaches the corpora cardiaca (CC) by nervi corporis cardiaci I. The CC is divisible into two distinct parts--central nervous part surrounded by the cellular cortical zone. The NSM of cerebral origin is stored and released from the CC. Intrinsic cells are found to be absent in the CC. AF positive material is found also in the corpora allata.

Animals↗
PubMed1979

[Isoprenaline, modifications of the turnover of ATP in the perfused rat heart].

5 hrs after a single sub-cutaneous injection of the drug in a dose of 5 mg/kg, the ATP concentration was reduced by 15%, the incorporation of 14C adenine was augmented by 20% and the turnover of ATP was accelerated: the reduction of specific radioactivity attained 16%, 75 mn after the period of marquage, instead of 7% in the control hearts. When the drug was added to the perfusion fluid, there was no supplementary reduction of the ATP concentration and the action on the nucleotide turnover only existed if the ATP level was reduced by a pretreatment: the reduction of specific radioactivity then attained 24% after 75 min. of perfusion.

Adenine↗
PubMed1978

Histo-physiology of the salivary glands of the red cotton bug, Dysdercus koenigii (Pyrrhocoridae-Heteroptera)--histological, histochemical, autoradiographic and electron-microscopic studies.

1. Gross morphology, histology, histochemistry and ultrastructure of the salivary glands of Dysdercus koenigii have been studied. The mode of origin of saliva was investigated by tracer techniques. 2. Differences in histological structure of the glandular lobules, consistency and staining properties of the lumen contents, as also in their capability to incorporate materials from haemolymph have been observed, pointing to a possible division of labour among the different parts of the gland. 3. 3H-thymidine experiments showed that some of the nuclei of the gland cells incorporate the label asynchronously, indicating their polyploid growth or repair DNA synthesis or even specific gene amplification. 4. 3H-uridine incorporation patterns showed that the gland cell nuclei are the principal centres of RNA synthesis. The synthetic products move into the cytoplasm and then into the glandular lumen. The RNA exported into the lumen conjugates with the protein to form RNP which provides the material for the formation of the protective sheath around the mandibular, and maxillary stylets at the time of piercing and sucking. 5. Autoradiographic experiments with 3H-L-histidine showed that the site of heavy labelling shifts from outside inwards with progressive incubation times, indicating that the glandular epithelium is capable of transporting haemolymph materials (proteins?) into the lumen. Some of the haemolymph protein fractions could possibly be used as the precursors of salivary components, in addition to the endogenously synthesised materials. 6. Salivary histochemical studies revealed the presence of glycogen both in the lumen and in the granular epithelium. 3H-glucose labelling patterns are in agreement with the histochemical localization of glycogen and suggest that the blood sugar (trehalose) might be appropriated by the gland cell epithelium for the formation of glycoproteins. 7. Ultrastructural observations of the gland cells showed that the basal borders of the cells are highly folded to form pits. Pinocytotic uptake of the haemolymph materials may be facilitated by these pit formations. The apical borders of the cells facing the lumen develop numerous microvilli and the secretion granules escape into the lumen by pinocytosis, as revealed also by the autoradiographic studies with tritiated histidine. The distribution of golgi vesicles, mitochondria, microtubules is not uniform. They tend to show a higher density towards the apical border than towards the basal border of the cells. This difference may be related to the well-known functions of these organelles in packing the secretion products and to provide energy and channels for their transport. The rER exists in the form of numerous vesicles scattered evenly throughout the cytoplasmic space. But they also exist as stacks of membranes. Their proximity with golgi vesicles seems to be significant for the packing process of the secretion products.

Animals↗
PubMed1976

Conformational flexibility and protein folding: rigid structural fragments connected by flexible joints in subtilisin BPN.

Conformational energy calculations are used to analyze the interactions of structural substructures in subtilisin BPN. These substructures are kept fixed or "rigid" so that the only variables in the calculations are the backbone segments that separate them. The flexible segments are assumed to be free turns. Using this representation of the protein it is possible to predict both a likely order of events along a folding pathway and preferred modes of conformational changes of the native protein. Moreover, when the native structure has been perturbed by moving the substructures apart, it is possible to assess the range of interactions that return the protein, upon energy minimization, to its original conformation. These results suggest an approach to the folding problem based on the piecemeal formation of tertiary structure from smaller prefolded fragments.

Computers↗
PubMed1975

p-Azobenzenearsonate-L-tyrosine-mediated helper function in immune responses of guinea pigs and rats.

A small bifunctional antigen (4-hydroxy-5-iodo-3-nitrophenyl)acetyl-epsilon-aminocaproyl-L-tyrosine-azobenzene-p-arsonate [NIP-cap-TYR(ABA)] was found to induce fair humoral antibody formation against NIP-cap but very little anti-ABA-TYR. This was observed in rats and guinea pigs. Prior immunization with ABA-TYR, either as such or coupled to dodecanoylated bovine serum albumin (lipid-BSA), primed rats for an enhanced anti-NIP response to NIP-cap-TYR(ABA). An attempt to encourage rats to produce anti-ABA-TYR in response to the bifunctional antigen by priming them with NIP-cap-lipid-BSA failed. Priming with ABA-TYR was dose-dependent. An injection of 1.5-15 nanomoles per rat primed for an increased production of anti-NIP while 150 nanomoles did not. Adult thymectomized x-irradiated rats had a poor anti-NIP response to the bifunctional antigen if they were reconstituted with T-enriched lymphoid cells from control mice, but a good response if reconstituted with similar cells from ABA-TYR-primed syngeneic rats.

Animals↗