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Biomedical subjects

R Padmanabhan

Publications and source records attributed to R Padmanabhan.

At least 163 records · Page 9Linked to original sources
PubMed1980

The nucleotide sequence of the right-hand terminal SmaI-K fragment of adenovirus type 2 DNA.

The primary structure of the SmaI-K fragment of adenovirus type 2 (Ad2) DNA has been determined. This region includes one of the origins of DNA replication (Winnacker, 1978; Sussenbach and Kuijk, 1978). A leader sequence for an early mRNA in region 4 (Berk and Sharp, 1977; 1978) has also been mapped in this region. The comparison of the primary structure of this region in Ad2 DNA with the corresponding region in Ad5 DNA shows a remarkable homology which may be significant in view of the fact that Ad2 and Ad5 DNAs can interchangeably function in the in vitro replication system of Challberg and Kelly (1979).

Adenoviruses, Human↗
PubMed1980

Comparative sequence analysis of the inverted terminal repetitions from different adenoviruses.

The comparative nucleotide sequences of the region of inverted terminal repetition from a representative member of group C (nononcogenic), group B (weakly oncogenic), and group A (highly oncogenic) adenoviruses are analyzed. Our data show that (i) the length of this unique region increases with the oncogenicity of the serotype, (ii) a unique homologous region--14 nucleotides long--is present exactly at the same distance from the terminus, and (iii) a hexanucleotide sequence, T-G-A-C-G-T, is present at the site where the terminal repetition diverges.

Adenoviruses, Human↗
PubMed1980

Effect of natural litter size on the post-natal growth in CF rats.

The litter effect among natural litters (with minimal differences in size i.e. 6, 8 and 9) on the growth was studied in CF rats from post-conception (PC) day 22 to 90 by somatometric techniques. Body weight was found to be significantly low in larger litters up to PC day 50 although the difference persisted numerically until PC day 90. Crown-rump length, tail length and patellocalcaneal length were significantly (less than 0.001) reduced in larger litters. Growth rate curves substantiated these observations. Since the differences in size among the three groups of litters were too small to cause any nutritional deprivation and the natural potential for growth was not altered, differences in mother-offspring and/or offspring-offspring emotional interactions could be the possible factor responsible for the growth rate differences.

Animals↗
PubMed1979

Specificity and mode of cleavage of the pH 4.0 endonuclease from adenovirus type 2 - infected KB cells.

Adenovirus type 2 or lambda DNA was digested with the pH 4.0 endonuclease, purified from adenovirus 2-infected KB cells. The enzyme produces a limit digest of approximate size in the range of 140-210 base pairs long. The termini of the DNA fragments generated by the endonuclease digestion had 3'-P and 5'-OH groups. The 3' and 5' end groups of the products were analyzed. Our data indicate that 3' end group was a purine (68-76%), dA occuring about twice the frequency of dG. The 5' end group was either dG or dC with equal frequency. Data obtained by treatment of the 5' labeled endonuclease product of lambda DNA with single-strand specific S1 nuclease from Asperigillus oryzae or exonuclease VII from Escherichia coli indicated that the majority of the products had a short 5' protruding ends. The mode of cleavage of this endonuclease seems to be through initial formation of several single-strand breaks with some base specificity. If these breaks are at close proximity on opposite strands, double-stranded fragments with protruding ends are generated.

Adenoviruses, Human↗
PubMed1979

Isolation and characterization of a homogeneous DNA-protein complex from adenovirus type 2 virion.

Adenovirus DNA-protein complex purified by sedimentation on a sucrose gradient containing 4 M-guanidine hydrochloride was found to contain other virion proteins in addition to the terminal protein of mol. wt. 55000. In this report, we describe a simple and rapid method for the isolation of a homogeneous DNA-protein complex. The procedure involves gel electrophoresis of the complex on agarose in the presence of sodium dodecyl sulphate. DNA was found to migrate into the gel with a single protein of mol. wt. 55000 tightly attached to it. Restriction enzyme cleavage analysis of the DNA-protein complex shows that the protein is associated with the two terminal fragments.

Adenoviruses, Human↗
PubMed1979

Observations on the topographical relations of spinal nerve roots in the rat.

The spinal cord along with the ventral and dorsal roots (C1-S4) were dissected out in 10 male and 5 female CF rats. The vertebral levels of origin and exit of the spinal nerve roots and termination of the spinal cord were recorded. It was observed that from the mid-cervical to the sacral region, the roots arose increasingly at cranial levels compared to their levels of exit. This disparity was at its maximum in the lumbar and sacral segments. The spinal cord terminated between the third and fourth lumbar vertebrae. There was no sexual dimorphism either at the level of termination of the cord or at the levels of origin and exit of origin and exit of the various nerve roots.

Animals↗
PubMed1979

Effect of chlorpromazine on skeletogenesis. The result of maternal administration of the drug in experimental rats.

Chlorpromazine hydrochloride (CPZ) is known to induce intrauterine and extrauterine growth retardation. A single dose of CPZ (100 mg/kg) was administered to pregnant CF rats on the 14th day of gestation (sperm positive=day 0). Fetuses were collected from the 16th to the 20th day of gestation and processed for alizarin red-S stain. Ossification was delayed by 1 to 3 days in the long bones of the extremities, by 1 day in the scapulae and by 2 to 3 days in the ilium. Ischium and pubis remained unossified until the 20th day of gestation. Ossification of the skull bones was also delayed as manifested by the presence of wide sutures in the treated cases. The number and range of ossified vertebral bodies and arches in the treated group were always less than those in the control group. The sternebrae were most affected. The ribs also showed a significant delay in maturity.

Animals↗
PubMed1979

Growth retardation in rat fetuses induced by chlorpromazine hydrochloride (CPZ).

Maternal administration of 100 mg/kg of chlorpromazine hydrochloride on 14th gestation day led to a significant (P less than 0.001) intrauterine growth retardation (IUGR) in rat fetuses collected from 16th--20th days of gestation. Besides weight of the fetus, other measurements were used to assess the stunted growth, e.g. CR length, tail length and trans-umbilical distance (TUD). The latter was as efficacious as the weight since with each one of them the IUGR was found in 88% of fetuses at--2SD level on 20th day of gestation. The different components of the fetal environments, e.g. weight and volume of placenta, length of the umbilical cord, weight and volume of amniotic fluid were also investigated which showed a positive correlation between alteration in the fetal environment and IUGR.

Amniotic Fluid↗
PubMed1978

An endodeoxyribonuclease of human KB cells. Purification and properties of the enzyme.

An endodeoxyribonuclease has been purified 750-fold from human KB cells. The purified endonuclease requires Mg2+ for maximum activity: Mn2+ was less than half as active and Ca2+ inhibited the reaction. The optimum pH is 8.8 in Tris-HCl and the optimum buffer concentration is 10 mM. KCl (and NaCl), --SH-reacting reagents, and tRNA strongly inhibit the reaction. An apparent molecular weight of 54,000 was determined by sedimentation in a glycerol gradient. The purified endonuclease cleaved native, double-stranded adenovirus 2 DNA, and the reaction proceeded stepwise during the initial stage of degradation by cleavage of the DNA substrate in half, then in half again, etc. At longer digestion times, single strand scissions were detected. RNA was not a substrate for the enzyme. Poly(dG) . poly(dC) was susceptible but poly(dA) . poly(dT) was resistant to degradation. Hydrolysis of adenovirus 2 DNA yielded double-stranded polynucleotides containing 5'-phosphoryl and 3'-hydroxyl termini with short, single-stranded regions presumably at the ends. More than 50% of the product of a limit digest had a chain length greater than 35 to 40 nucleotides. Analysis of the 5' and 3' end groups of the digestion products indicated a preference for the site of the enzymatic cleavage; thymidylic acid residues were present at the 5' end and deoxyguanosine residues at the 3' end, each with a frequency of 40 to 50%.

Cell Line↗
PubMed1978

A quantitative assessment of post-natal development in CF rats.

The post-natal development in CF rats from 5 litters was followed anthropometrically from the day of delivery to day 75. Weight, CR length, tail length and patello-calcaneal length of individual rats were measured every day and the rate of gain per day was calculated for each parameter. During this period, the rate of gain in weight showed two peaks (from days 26 to 30 and 56 to 60). The CR length and tail length had only one such peak (from days 16 to 20 and 21 to 25, respectively). The patello-calcaneal length rather exhibited an initial fall in the rate of growth up to day 45 followed by a slight increase till day 50 after which it became steady. Robustness as judged by: formula: see text was found to be maximum in the first few days after birth. Body weight or: formula: see text showed better correlations with other parameters than the gross age. The growth curves appeared as straight lines having breaks, indicating that though the growth was exponential it had sudden changes in its rate.

Age Factors↗