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Biomedical subjects

R C Gupta

Publications and source records attributed to R C Gupta.

At least 325 records · Page 18Linked to original sources
PubMed1979

Ribosome binding site analysis of ovalbumin messenger ribonucleic acid.

The region of the ovalbumin messenger ribonucleic acid (mRNAov) molecule bound to the 40S ribosomal subunit and its associated initiation factors in the wheat germ cell-free translation system were isolated and characterized. Two mRNAov fragments, 87 and 92 nucleotides in length, were protected from T1 ribonuclease digestion by binding of guanosine 5',beta,gamma-methylenetriphosphate and were shown by hybridization and fingerprint mapping to be derived from the 5' end of mRNAov. Both these mRNAov fragments were of sufficient length to contain both the cap structure and the AUG initiation codon. Four T1-resistant oligonucleotides, prepared by direct digestion of mRNAov with T1 ribonuclease were also found to bind to the wheat germ 40S ribosomal subunit. Nucleotide sequence analysis of these oligonucleotides revealed (1) that they were not a subset of the ribosome binding fragments described above, (2) that they were derived from within the mRNAov molecule (one from within the coding region and three from the noncoding region at the 3' end of the mRNAov molecule), and (3) that three of the four mRNAov nucleotides contained 3'-terminal AUG trinucleotides. These data suggested that features of the mRNAov molecule in addition to the nucleotide sequence might be important in specifying the correct ribosome binding site for the initiation of protein synthesis. The amount of mRNAov bound to the wheat germ 40S ribosomal subunit in a preinitiation complex was found to vary inversely with the potassium ion concentration. Lowering the potassium concentration to levels suboptimal for translation also resulted in the protection of larger fragments of the mRNAov molecule derived from the same 5'-end region as the ribosome binding fragments described above. The ability of the cap analogue 7-methylguanosine 5'-phosphate (m7G5'p) to reduce the amount of mRNAov bound to the wheat germ 40S ribosomal subunit was found to depend directly on thepotassium concentration. Interestingly, the effects of potassium on the amount of mRNAov bound in a preinitiation complex and the inhibition of this binding by m7G5'p could be observed by changing the potassium concentration after binding had occurred. These data suggested that the interaction between the wheat germ 40S ribosomal subunit and mRNAov was very sensitive to the ionic environment.

Animals↗
PubMed1979

The nucleotide sequence of human tRNAGly (anticodon GCC).

The sequence of tRNAGCCGly from human placenta was determined by recently developed postlabeling techniques. The tRNA was digested completely with RNases T1 and A in the presence of alkaline phosphatase, the oligonucleotides were 3'-terminally (3H)-labeled, mapped on PEI-cellulose thin layers, isolated, and sequenced by methods based on base-specific cleavages. Overlaps were obtained by readout sequencing techniques on polyacrylamide gels and PEI-cellulose thin layers. The thin-layer readout technique was used also to locate and identify modified nucleotides. The primary structure was found to exhibit a large degree of homology (94.6%) with silkworm tRNAGCCGly but only 67.6% homology with human tRNACCCGly.

Anticodon↗
PubMed1979

Rapid print-readout technique for sequencing of RNA's containing modified nucleotides.

A rapid, simple, and highly sensitive method for sequence analysis of RNA was developed, which consists of the following steps: (i) controlled hydrolysis of the RNA by brief heating in water; (ii) (32P)-labeling of 5'-hydroxyl groups of the fragments produced in (i); (iii) resolution of labeled fragments by size on polyacrylamide gels giving the familiar "ladder"; (iv) contact transfer ("print") of the ladder from the gel to a PEI-cellulose thin layer; (v) in situ treatment of the ladder with RNase T2 resulting in the release of 5'-(32P)-labeled nucleoside-3',5' diphosphates; (vi) contact transfer and thin-layer separation of (32P)-labeled nucleotides on PEI-cellulose in ammonium sulfate and ammonium formate solvents; (vii) autoradiography. The chromatographic behavior of the 4 major and 18 modified nucleotides was determined. The positions of major and modified nucleotides in the sequence can be read directly from the separation patterns displayed on X-ray film. As this is the only sequencing method presently available that allows one to display and identify directly the positions in the RNA chain of major and modified nucleotides, no additional procedures are required to analyze the latter.

Base Sequence↗
PubMed1979

Yeast tRNA Leu UAG. Purification, properties and determination of the nucleotide sequence by radioactive derivative methods.

A second major species of leucine tRNA, tRNA Leu UAG (formerly designated tRNA Leu CUA) was purified from baker's yeast in a three-step procedure entailing BD-cellulose chromatography in the presence and absence of Mg2+ and Sephadex G-100 gel filtration. Results of aminoacylation and partial RNase T1 digestion experiments showed that this tRNA retains a native conformation under conditions that denature yeast tRNA Leu m5CAA (tRNA3 Leu). The primary structure of baker's yeast tRNA Leu UAG was elucidated by application of sensitive radioactive isotope derivative ("postlabeling") methods. Complete RNase T1 and A and partial RNase U2 fragments, prepared from non-radioactive tRNA and 5'-half and 3'-half molecules, were separated by two-dimensional polyethyleneimine-cellulose anion-exchange thin-layer chromatography and isolated by a novel micropreparative procedure affording high yields of these compounds in sufficient purity for subsequent tritium derivative analysis. Base composition and sequence of oligonucleotides were analyzed by tritium derivative methods. Molar ratios of the fragments were determined from the radioactivity of 3H-labeled nucleoside trialcohols in combination with base analysis. 2'-O-Methylated guanosine was characterized using the [gamma-32P]ATP/polynucleotide kinase reaction. The analysis of classical complete and partial RNase digests by the tritium derivative methods yielded the complete nucleotide sequence of the tRNA. A total of about 20 A260 units of the RNA was used for analysis, i.e. considerably less material than required for conventional spectrophotometric analysis. A different sequencing approach, consisting of a combination of "readout sequencing" with tritium sequencing of complete RNase T1 and A fragments, was applied to the 3'-half molecule. The 3'-half molecule was labeled with 32P at its 5' terminus, partially degraded with RNase T1, U2, and Phy1 and with alkali, and subjected to polyacrylamide gel electrophoresis. The sequence was read off the gel on the basis of cleavage patterns and size of the fragments. While the readout procedure provided only the positions of A, U, C, and G residues in the chain, additional information from tritium derivative analysis was utilized to define the positions of the modified nucleosides. The readout sequencing procedure was found to require less than 0.01 A260 unit of RNA and the analysis of the complete fragments about 6 A260 units. Interesting structural features of tRNA Leu UAG are (a) the location of unique, leucine tRNA iso-acceptor-specific sequences next to U-8, a constant nucleotide participating in synthetase recognition, (b) the occurrence of 1-methyladenosine in the T loop, a modification not present in the structurally related tRNA Leu m5CAA, and (c) the unusual presence of an unmodified uridine in the first position of the anticodon, which may be related to the unusual coding properties reported for this tRNA.

Adenine↗
PubMed1979

Comparison of three immunoassays for immune complexes in rheumatoid arthritis.

Three widely used radioassays that depend on different principles for the measurement of circulating immune complexes (CIC) in biologic fluids are the monoclonal rheumatoid factor (mRF), Raji cell, and C1q binding tests. A comparison of the ability of these methods to measure immune complex-like material in 71 sera and 30 synovial fluids of 91 patients with rheumatoid arthritis (RA) was carried out by a group working in adjacent laboratories in a single institution. The highest number of abnormal levels in the seropositive group was detected by the C1q binding assay (91%). Levels of CIC by the mRF and Raji cell tests were elevated in 81% and 76% of the patients, respectively. The closest correlation was between the Raji and mRF tests (r = 0.44 and P = 0.002) although one depends on complement fixation and one does not. Though significant correlations between the levels of CIC determined by the C1q test and either the mRF (P = 0.2) or Raji cell (P = 0.3) assay were not found in this group, 59% of the samples had elevated levels by all three tests. The frequency of CIC in the sera of patients with seronegative RA was much lower, with the C1q test again giving the highest number of abnormal results (29% versus 16% and 12% for the Raji and mRF tests). In view of the technical problems associated with these tests, particularly lack of a uniform reliable standard, it is likely that all three tests measure the same material in most RA sera and that some of the differences observed are related to inherent variability in the tests themselves rather than intrinsic differences among the CIC detected in these samples.

Adult↗
PubMed1979

Carcinogenicity of hexachlorocyclohexane (BHC) in pure inbred swiss mice.

Inbred Swiss mice were treated with technical BHC (1) orally with the diet or by intubation and (2) by skin painting. The total duration of the experiment was 80 weeks. There was no difference in body growth and mortality between the experimental and control groups. Symptoms of intoxication in the form of convulsions and tendency of circling in one direction with drooping ears were observed alongwith corneal opacity 40 weeks after the experiment. Oral BHC treatment resulted in a significant increase in the incidence of liver tumours and tumours of lymphoreticular tissue. Males and females were equally susceptible. Skin painting of mice did not significantly increase the incidence of tumour.

Animals↗
PubMed1979

A monitoring study of workers handling pesticides in warehouses and godowns.

Monitoring observations made on 60 operators involved in pesticide application work in godowns and warehouses and 60 matched control workers are reported. Occupational exposure history and medical history are noted. Biochemical investigations, plasma and RBC cholinesterase estimations are included along with medical examination of the workers. Workers were found to be mostly exposed to Celphos, DDVP, Malathion, Pyrethrum, etc, and the use of protective devices were very limited. Cases of significant reduction in plasma and RBC cholinesterase activity were found. Frequency of symptoms like dizziness, headache, lachrymation, burning sensation in eyes, nausea and anorexia, etc, were much more in the exposed workers. No cases of clinical poisoning attributable to occupational exposure to pesticides were reported by the workers.

Adult↗
PubMed1979

Estimation of daily sperm production rate (DSPR) by quantitative testicular histology in Buffalo-bulls (Bubalus bubalis).

Testes and epididymides from six sexually rested buffalo-bulls were removed during breeding season. The average weight of the testicular parenchyma was 138.62 g, of which the tunica albuginea accounted for 8.45 g. Relative distribution of spermatozoa in caput, corpus, and cauda epididymides averaged 5.42, 0.75, and 11.45 billion, respectively. Total epididymal sperm reserve per bull was 36.2 billion. The efficiency of sperm production was quite uniform and averaged 14.5 x 10(6) sperm per gram of testicular parenchyma per day with a mean of 2.02 x 10(9) sperm per testis. Thus a typical buffalo-bull produces about 4 x 10(9) sperm daily during breeding season.

Animals↗
PubMed1979

Delta-9-tetrahydrocannabinol levels in street samples of marijuana and hashish: correlation to user reactions.

In a 6-year period, 435 alleged cannabis samples were accessioned by an urban street drug analysis program, and clinical histories were correlated with laboratory results. The most common reason for submission of a sample was suspicion of adulteration; however, such samples were usually unadulterated but had high potency as measured by delta 9-tetrahydrocannabinol concentration. Adverse reactions occurring in nonadulterated samples were not associated with high potencies. The validity of cannabis products distributed illicitly and analyzed was over 94%. Exotic varieties were more potent than less expensive cannabis. The absolute amount of delta 9-tetrahydrocannabinol ranged from 1.5 to 144.9 mg.

Cannabis↗
PubMed1979

New CNS-active 3-methyl-4-substituted methyl-delta 2-isoxazolin-5-ones.

Eight 3-methyl-4-substituted methyl-delta 2-isoxazolin-5-ones were synthesized and evaluated for central nervous system (CNS) activity. All compounds at a concentration of 1 . 10(-3) mol/l inhibited rat brain monoamine oxidase (MAO) in vitro and provided protection against pentetrazole-induced convulsions in mice at a dose of 100 mg/kg i.p. Compounds 2 and 6 showed 80% protection. All isoxazolines (100 mg/kg i.p.) potentiated pentobarbital sleeping time in mice.

Animals↗