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Biomedical subjects

S Prasad

Publications and source records attributed to S Prasad.

At least 217 records · Page 12Linked to original sources
PubMed1990

Isolation and sequence analysis of Caenorhabditis briggsae repetitive elements related to the Caenorhabditis elegans transposon Tc1.

We have identified two repetitive element families in the genome of the nematode Caenorhabditis briggsae with extensive sequence identity to the Caenorhabditis elegans transposable element Tc1. Five members each of the TCb1 (previously known as Barney) and TCb2 families were isolated by hybridization to a Tc1 probe. Tc1-hybridizing repetitive elements were grouped into either the TCb1 or TCb2 family based on cross-hybridization intensities among the C. briggsae elements. The genomic copy number of the TCb1 family is 15 and the TCb2 family copy number is 33 in the C. briggsae strain G16. The two transposable element families show numerous genomic hybridization pattern differences between two C. briggsae strains, suggestive of transpositional activity. Two members of the TCb1 family, TCb1#5 and TCb1#10, were sequenced. Each of these two elements had suffered an independent single large deletion. TCb1#5 had a 627-bp internal deletion and TCb1#10 had lost 316 bp of one end. The two sequenced TCb1 elements were highly conserved over the sequences they shared. A 1616-bp composite TCb1 element was constructed from TCb1#5 and TCb1#10. The composite TCb1 element has 80-bp terminal inverted repeats with three nucleotide mismatches and two open reading frames (ORFs) on opposite strands. TCb1 and the 1610-bp Tc1 share 58% overall nucleotide sequence identity, and the greatest similarity occurs in their ORF1 and inverted repeat termini.

Animals↗
PubMed1990

Depression in general practice: a comparison of flupenthixol dihydrochloride and dothiepin hydrochloride.

A single-blind, parallel group, general practice study was carried out in 153 patients with mild to moderate depression to compare the efficacy and tolerability of flupenthixol dihydrochloride and dothiepin hydrochloride. Patients were allocated at random to receive single daily doses of either 1 mg flupenthixol in the morning or 75 mg dothiepin in the evening, and this dose could be doubled at the end of 2 weeks in the event of inadequate response. Assessments were made on entry and after 1, 2, 4 and 6 weeks of treatment using the Hamilton Depression Rating Scale, a 4-point severity scale and an unwanted symptoms checklist. The results showed that both treatments significantly improved the patients' condition over 6 weeks, and there was a significant difference in favour of flupenthixol at end-point. Both drugs were well tolerated, although persistence of anticholinergic side-effects in the dothiepin group resulted in a trend favouring flupenthixol. One patient in the flupenthixol group attempted suicide by overdose but made a complete recovery.

Adolescent↗
PubMed1990

Distribution of high mobility group proteins in different tissues of rats during aging.

The distribution of high mobility group (HMG) proteins has been studied in the liver, brain, kidney, lung, spleen, testis, thymus, and heart of young (19 weeks) and old (118 weeks) rats. These proteins were extracted with perchloric acid, fractionated by CM-Sephadex column chromatography, and analysed by acetic acid-urea polyacrylamide slab gel electrophoresis. As compared with that in young rats, the level of total HMG proteins in the old increased in liver and lung, decreased in thymus, heart, brain, and kidney, and remained unchanged in spleen and testis. In particular, the levels of HMG 1 and 2 were maximum in the thymus of young rats and dropped drastically in the old. However, the amount of HMG 17 was high in the spleen of both young and old rats, though it was comparatively higher in the former. Such age-dependent variation in the level of HMG proteins of different tissues denotes indirectly differences in the functional state of chromatin, and in growth and activity of cells, during aging.

Aging↗
PubMed1990

Otologic disease in the acquired immunodeficiency syndrome.

It appears that true otologic manifestations of AIDS are rare and that incidental otologic disease associated with AIDS is more common. A review of the literature revealed that otitis externa, acute otitis media, recurrent acute otitis media, otitis media with effusion, chronic suppurative otitis media with cholesteatoma, and herpes zoster oticus may all represent incidental otologic disease occurring in patients with AIDS. Chronic otitis media without cholesteatoma (P carinii-infected aural polyps), sensorineural hearing loss, acceleration of otosyphilis from the latent stage, and development of Kaposi's sarcoma of the external auricle or nasopharynx may represent true otologic manifestations of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

A dot-blot method for screening polyclonal and monoclonal antisera to poly(ADP-ribose).

ADP-ribosylation reactions play a key role at several points in cellular regulation and repair of DNA damage. The use of polyclonal or monoclonal antisera to poly(ADP-ribose) as probes to localize the site(s) of action of the polymer offers a promising tool for these studies. We report here a simple, sensitive method for detection and titration of these antisera to poly(ADP-ribose) using nitrocellulose membrane (NC) as a support for a dot-blot analysis. We take advantage of the fact that a highly labeled poly(ADP-ribose) preparation can be obtained by incubation of a 0.3 M KCl extract prepared from calf thymus nuclei with 32P-NAD. Such a preparation of labeled antigen is used as a reagent to detect the positive antibody spots on the NC with negligible background. Subsequent titration of the antisera and their semi-quantitative evaluation are also feasible using the dot-blot method. The sensitivity of the assay is only limited by the specific activity that can be achieved for the labeled polymer prepared as the antigen probe. The advantage of this method is that it eliminates the need to prepare pure, highly radiolabeled polymer as well as the fact that several samples can be handled on the membrane simultaneously. We demonstrate application of this technique for screening sera from patients with systemic lupus erythematosus (SLE) for anti-poly(ADP-ribose) antibodies. Further, we also extend the use of these sera for immunoquantitation of ADP-ribosylated proteins in six human tumor cells in tissue culture.

Animals↗
PubMed1989

The effect of desferrioxamine on lipid peroxidation and survival of ischaemic island skin flaps in rats.

To produce total necrosis, it was found necessary to subject pedicled groin flaps in rats to 16 hours of warm ischaemia (WI) (whether clamped in situ or removed and maintained at 37 degrees C ex vivo before replantation). Biochemical markers of lipid peroxidation (Schiff bases and thiobarbituric acid (TBA)-reactive material) in homogenates of full thickness skin or of subcutaneous fat rose significantly (p less than 0.001) after 14 hours of WI and reperfusion in vivo. Desferrioxamine (15 mg/kg i.v.) administered systemically either before 14 h WI only, before reperfusion only after 14 h WI or in both circumstances inhibited these rises to near-control (fresh tissue) levels. In survival experiments, this treatment also protected these flaps from necrosis (p less than 0.01).

Animals↗
PubMed1989

Evidence that plasminogen activator is not involved in basement membrane penetration at avian gastrulation.

We have used the method of radial caseinolysis in agarose to assay for the presence of plasminogen activator in the primitive streak cells of the early chick embryo. These cells are undergoing an epithelial-mesenchymal transformation in the process of the differentiation of mesoderm cells from the ectoderm. In the primitive streak, the epithelial cells, after penetrating the basement membrane, ingress and invade the underlying tissue space as fibroblast-like mesenchyme cells. In contrast to some other early embryonic invasionary and migratory events, we find no evidence for the participation of plasminogen activator in this process.

Animals↗
PubMed1989

Age-specific methylation of high-mobility-group proteins of the rat liver and its modulation by spermine and sodium butyrate.

Liver slices from young (20 weeks) and old (117 weeks) rats were incubated with [methyl-14C]methionine in the absence or presence of spermine or sodium butyrate. The high-mobility-group (HMG) non-histone proteins were extracted from the liver with perchloric acid and separated by acid-urea polyacrylamide slab gel electrophoresis. Methylation of HMG proteins decreased drastically in old rats. Whereas spermine inhibited the methylation of total HMG proteins in young rats, it had no effect in old age. On the contrary, sodium butyrate did not change the incorporation of methyl groups into total HMG proteins of young rats, but inhibited that of old rats. Particularly, the incorporation of [14C]methyl groups into HMG 2 was enhanced but into other HMGs it was reduced by both effectors in young and old age. Such discrepancies in the methylation of HMG proteins and their differential modulation by spermine and butyrate might affect the higher-order organization of chromatin and consequently destabilize the expression of genes during aging.

Aging↗
PubMed1989

Equine coital exanthema (EHV-3 virus) infection in India.

A progenital disease encountered at one equine stud farm at Bangalore in Southern India during 1987 was investigated and confirmed as equine coital exanthema on the basis of characteristic lesions and clinical symptoms, isolation of equine herpes virus-3 (EHV-3) from the scabs collected from animals having active lesions and demonstration of neutralizing antibodies in the sera of recovered mares and stallion. This is the first authenticated report of the occurrence of equine coital exanthema in India due to EHV-3.

Animals↗
PubMed1989

Invasion of a basement membrane matrix by chick embryo primitive streak cells in vitro.

At the time of gastrulation in the chick embryo the upper epiblast layer penetrates its own basement membrane at the primitive streak so that its cells may invade the underlying tissue space. In so forming the primary mesoderm, the cells undergo a concomitant epithelial-to-mesenchymal transformation. In this study, epiblast tissue has been explanted onto a basement membrane gel in order to examine its invasive potential. Fully ingressed primary mesoderm cells were able to penetrate the gel as individual cells, during the course of which the texture of the gel was disrupted. By contrast, epiblast tissue taken from the immediate vicinity of the primitive streak penetrated the gel, but only as a coherent tongue of cells and without gel disruption. These tongues of cells did not undergo the epithelial-to-mesenchymal transformation, and consequently spread as a epithelial sheet when replated on glass. Thus, the absence of gel disruption correlated with the failure of transformation, suggesting that these two events may be linked and that they may require in situ cell interactions for their manifestation. Tissue from the lateral epiblast failed to penetrate the gel. Instead, this tissue either spread on the gel surface or rounded up into a hollow sphere with the basal surface of the cells innermost. In the former case, despite the cell spreading, no lamina densa was organized beneath the sheet, but in the latter case polarity reversal occurred with the formation of a new lamina densa at the cell-gel interface.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Extracellular matrix synthesis is required for the movement of sclerotome and neural crest cells on collagen.

During early embryogenesis cells of several different populations disperse by active cell movement from one location to another. Preexisting extracellular materials are major determinants of these dispersal patterns, but the cells are also able to modify their substrata by synthesizing and secreting extracellular matrix molecules as they move. In order to determine the contribution made by these deposited materials, several tissues from the early chick embryo have been cultured in the presence of inhibitors of extracellular matrix synthesis and secretion. The tissues examined were sclerotome cells from differentiated somites and neural crest cells. For comparison, undifferentiated somites were also cultured. The movement of these cells was compared in type I collagen gel culture and in conventional culture on artificial substrata. Inhibitors of collagen synthesis were used (cis-hydroxy proline and L-azetidine-2-carboxylic acid) in addition to a proteoglycan inhibitor (p-nitrophenyl-xylopyranoside) and a secretion inhibitor (monensin). Results indicate that sclerotome cells require collagen synthesis for movement in a collagen matrix. Reversal of the effects of collagen inhibitors, by proline and type II collagen, suggest that sclerotome cells normally condition the type I matrix in order to move in it. Inhibition of proteoglycan synthesis produced the greatest effect on the movement of neural crest cells regardless of the substratum, confirming an important role for these molecules in the crest migratory routes. The attachment of all cells to collagen was highly sensitive to the presence of monensin, which is known to reduce the deposition of glycosaminoglycans and fibronectin. These results suggest that conditioning of the extracellular matrix by newly synthesized material is required for cell attachment and movement during early development.

Animals↗
PubMed1988

Age-dependent effects of sodium butyrate and hydrocortisone on acetylation of high mobility group proteins of rat liver.

The in vitro acetylation of high mobility group (HMG) proteins and its modulation by sodium butyrate and hydrocortisone have been studied using liver slices of young (13-) and old (114-week-old) rats. Acetylation of total HMG proteins was significantly higher in young than old rats. HMG 1, in particular, showed greater acetylation than others. Whereas acetylation of HMG 1 and 2 decreased drastically, that of HMG 14 and 17 increased in old age. In young rats, sodium butyrate and hydrocortisone stimulated acetylation of HMG 14 and 17, and decreased that of HMG 2. Butyrate had no effect on HMG 1, but hydrocortisone decreased it. In old rats, butyrate and hydrocortisone decreased acetylation of all HMGs, except HMG 17, which was stimulated to a slight extent by butyrate.

Acetylation↗