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Biomedical subjects

S Prasad

Publications and source records attributed to S Prasad.

At least 19 recordsLinked to original sources
PubMed2026

Craniotomy versus Endoscopic Membranectomy in the Treatment of Non-Homogeneous Chronic Subdural Hematoma: A Pilot Randomized Parallel-Group Active-Controlled Trial (EMiT CSDH 2).

BACKGROUND: Chronic subdural hematoma (CSDH) is a prevalent neurosurgical condition with persistent challenges related to recurrence. Endoscopic membranectomy (EM) has shown promising results in managing symptomatic non-homogenous (SNH)-CSDH, but comparative evidence against craniotomy with membranectomy (CM) is lacking. OBJECTIVES: To compare the safety and efficacy of EM versus CM in managing SNH-CSDH. MATERIALS AND METHODS: A pilot randomized parallel-group active-controlled open- labeled superiority trial from September 2023 to November 2024 at Government Kilpauk Medical College, Chennai, India. Sixty patients with SNH-CSDH were randomized into EM and CM groups. Recurrence was the primary outcome. Secondary outcomes included operative time, complications, radiological indices, pain, hospital stay, and functional recovery. All patients were followed for six months. RESULTS: No recurrence was observed in either group at six months. Two CM patients required reoperation on postoperative day one ( P = 0.15). EM was associated with shorter operative time ( P = 0.02), lower incidence of post-operative subdural residual fluid ( P = 0.015), better early hematoma reduction/subdural space reduction index ( P = 0.008), midline shift/symmetry improvement index ( P = 0.001), and lesser surgical site swelling ( P < 0.001). All patients were ambulant and had a Glasgow coma scale (GCS) 15 at discharge and at six months (including reoperated patients). Pain scores and functional recovery were comparable. EM patients had shorter hospital stays ( P = 0.004) and no significant complications. CONCLUSION: EM demonstrated favorable early radiological outcomes, fewer complications, and comparable functional recovery and recurrence versus CM in SNH-CSDH. Independent reproduction and larger multicentric trials are needed for validity and generalizability.

Humans↗
PubMed1992

Bacterial components and the pathophysiology of injury to the blood-brain barrier: does cell wall add to the effects of endotoxin in gram-negative meningitis?

In animal models, the lipopolysaccharide (LPS) from Haemophilus influenzae contributes to all the signs of meningitis associated with living bacteria. However, when tested in vitro, the amount of LPS in cerebrospinal fluid (CSF) in natural disease shows much greater effects on leukocytes than on endothelial permeability. To investigate whether other bacterial components act with LPS to incite meningeal inflammation, animals were challenged intracisternally with H. influenzae lysates. Upon neutralization of endotoxin, leukocytosis was greatly attenuated, but protein accumulation in CSF persisted. Cell wall from H. influenzae induced meningeal inflammation in a pattern opposite to that of LPS. Its ability to induce blood-brain barrier permeability greatly exceeded its ability to induce leukocytosis in vivo. Thus, cell wall, by acting on endothelia, and LPS, by inducing leukocytosis, may cooperate to induce inflammation in H. influenzae meningitis. Optimal reduction of inflammation and tissue damage in meningitis may require agents directed against cell wall as well as LPS.

Animals↗
PubMed1992

Differing roles for platelet-activating factor during inflammation of the lung and subarachnoid space. The special case of Streptococcus pneumoniae.

Although well-characterized in the lung, the role of platelet-activating factor (PAF) in inflammation in the central nervous system is undefined. Using rabbit models of meningitis and pneumonia, PAF was found to induce significant blood-brain barrier permeability and brain edema at doses five times lower than those required to generate leukocyte recruitment to the subarachnoid space. Both leukocytosis and increased vascular permeability occurred in response to PAF in the lung. Antibody to the CD-18 family of leukocyte adhesion molecules inhibited leukocyte recruitment in response to PAF in the brain (greater than 80%); a similar level of inhibition in the lung required treatment with a combination of a PAF receptor antagonist (L-659,989) and anti-CD18 antibody. Treatment with L-659,989 decreased abnormal cerebrospinal fluid cytochemical values induced by intracisternal challenge with pneumococci but not Haemophilus influenzae, indicating a special role for PAF in pneumococcal disease. Antibodies directed at phosphorylcholine, a unique, shared determinant of bioactivity of PAF and pneumococcal cell wall, obviated the inflammatory potential of both agents. However, no evidence for a direct PAF-like activity of pneumococcal cell wall components was detected in vitro by bioassay using platelets or neutrophils. It is concluded that PAF can induce inflammation in the subarachnoid space. In brain, PAF effects appear to be mediated through CD-18-dependent events, while in lung, PAF effects independent of CD-18 are also evident. At both sites, PAF is of particular clinical importance during inflammation induced by pneumococci apparently due to a unique proinflammatory relationship between the pneumococcal cell wall teichoic acid and PAF.

Animals↗
PubMed1992

Double aortic arch.

In conclusion, the diagnosis of DAA should be suspected in an infant with either biphasic stridor or feeding-related respiratory distress. Radiographic studies combined with appropriate thorough endoscopic evaluation should confirm clinical suspicion. Thoracotomy with surgical division of the DAA has given excellent long-term results.

Aorta, Thoracic↗
PubMed1991

Integrin-mediated localization of Bordetella pertussis within macrophages: role in pulmonary colonization.

The adherence of Bordetella pertussis to human respiratory cilia is critical to the pathogenesis of whooping cough but the significance of bacterial attachment to macrophages has not been determined. Adherence to cilia and macrophages is mediated by two large, nonfimbrial bacterial proteins, filamentous hemagglutinin (FHA), and pertussis toxin (PT). PT and FHA both recognize carbohydrates on cilia and macrophages; FHA also contains an Arg-Gly-Asp (RGD) sequence which promotes bacterial association with the macrophage integrin complement receptor 3 (CR3). We determined that virulent B. pertussis enter and survive in mammalian macrophages in vitro and that CR3 is important for this uptake process. We then determined the relative contribution of CR3 versus carbohydrate-dependent interactions to in vivo pulmonary colonization using a rabbit model. B. pertussis colonized the lung as two approximately equal populations, one extracellular population attached to ciliary and macrophage surface glycoconjugates and another population within pulmonary macrophages. Loss of the CR3 interaction, either by mutation of FHA or treatment with antibody to CR3, disrupted accumulation of viable intracellular bacteria but did not prevent lung pathology. In contrast, elimination of carbohydrate-bound bacteria, either by a competitive receptor analogue or an anti-receptor antibody, was sufficient to prevent pulmonary edema. We propose that CR3-dependent localization of B. pertussis within macrophages promotes persistence of bacteria in the lung without pulmonary injury. On the other hand, the presence of extracellular bacteria adherent to cilia and macrophages in carbohydrate-dependent interactions is associated with pulmonary pathology.

Adhesins, Bacterial↗
PubMed1991

Isolation and characterization of a full-length cDNA encoding the 55-kDa rabbit zona pellucida protein.

A full-length cDNA (rc55) encoding the major rabbit zona pellucida (ZP) glycoprotein (55 kDa) has been cloned and sequenced. A lambda gt11 expression library was constructed using poly(A)+ mRNA isolated from sexually immature rabbit ovaries which contain large numbers of developing follicles. The rc55 cDNA was identified using affinity purified polyclonal antibodies specific to ZP antigens which are shared among mammalian species. The deduced amino acid sequence of the full-length rc55 clone was matched to the NH2-terminal 25-amino acid sequence obtained for this protein. The predicted amino acid sequence consists of 540 amino acids including a putative signal peptide of 18-24 residues and six potential N-glycosylation sites. The cDNA hybridizes to a 2000-base species of mRNA from rabbit ovary which is not detected in other rabbit tissues. The message is present early in ovarian follicular development and is approximately 600-fold greater in sexually immature as compared with sexually mature rabbit ovaries. This cDNA was expressed as a cro-beta-galactosidase fusion protein using the pEX expression vector. Antibodies against native rabbit ZP, affinity-purified on the recombinant 55-kDa ZP protein, were found to recognize the native rabbit ZP glycoprotein, indicating partial conservation of native epitopes in the expressed recombinant protein.

Amino Acid Sequence↗
PubMed1991

Analysis of age-associated alteration in the synthesis of HMG nonhistone proteins of the rat liver.

HMG proteins were extracted with 5% PCA or 0.35 M NaCl from whole tissue, nuclei or chromatin of the liver of young (19 weeks) and old (118 weeks) male rats. They were resolved on acetic acid-urea polyacrylamide gel. The electrophoretic patterns of the major HMG proteins 1, 2, 14 and 17 of both ages are similar. The in vitro synthesis of HMG 1 and 2 decreases, but that of HMG 14 and 17 increases considerably in the liver of old rats. The synthesis of different HMG proteins is modulated differentially by spermine, butyrate, dexamethasone and 3-aminobenzamide in the liver of young and old rats. These findings suggest that HMG proteins contribute to alterations in the organization of chromatin and expression of genes during aging.

Aging↗
PubMed1991

Differential methylation of HMG proteins by dexamethasone in the liver of aging rats.

In vitro methylation of HMG proteins was studied in young and old rats by incubating liver slices with (methyl-14C)methionine. The level of methylation of all the four HMG proteins was relatively higher in young, as compared to old rats. Dexamethasone stimulated the methylation of HMG 2 to 12-fold, and inhibited that of other HMGs in young rats. On the other hand, it stimulated all major HMG proteins except HMG 2, which remains unchanged in old age. Such differential methylation of HMG proteins induced by dexamethasone affects the structure and function of chromatin during aging.

Aging↗
PubMed1991

Preliminary results of left heart bypass in pigs using a heparin-coated centrifugal pump.

To assess the feasibility of left ventricular assist without systemic heparinization, we used a commercially available (Sarns 3M) centrifugal pump with tubing set and cannulas, all internally precoated for the purpose of this study with heparin, to bypass the left ventricle in 12 pigs for periods of either 1 or 3 hours. There was no significant activation of clotting and there was no sign of generalized embolization. However, on postmortem studies, 5 kidneys out of 22 examined showed signs of minimal thromboembolism. This experiment shows that artificial left ventricular assist, free of systemic heparinization but using heparin precoating, is feasible and safe, at least for a short period of time.

Animals↗
PubMed1991

Possible roles for TGF beta 1 in the gastrulating chick embryo.

We have examined the immunocytochemical distribution of TGF beta 1 (transforming growth factor beta 1) in the gastrulating chick embryo, and have correlated the results with the ability of this factor to promote in vitro changes in the phenotype of mesoderm and epiblast cells. The findings, together with the demonstration that exogenous TGF beta 1 is also able to modulate extracellular matrix deposition by these cells in culture, are consistent with a role for this factor in the formation and morphogenesis of the early mesoderm. Immunofluorescence analysis, using an antibody to the amino-terminal fragment of TGF beta 1, indicates that this factor is located in, or between, cells of the medial epiblast, Hensen's node and primitive streak. At Hensen's node, cells of the hypoblast were also strongly labelled. Ingressed mesoderm cells, lateral to the streak, show considerably stronger and more diffuse labelling than the overlying epiblast cells. Although the fluorescent labelling appears to be associated with the extracellular matrix surrounding the mesoderm cells, it is not bound to hyaluronic acid, which is the preponderant molecule in the matrix at this time in development. When added exogenously to cultures of mesoderm cells growing with epithelial characteristics on fibronectin, TGF beta 1 effects an epithelial-mesenchymal transformation within 24 h. The reverse transformation is effected in mesoderm cells grown on laminin, while the epiblast cell phenotype is not affected by this treatment regardless of the substratum. TGF beta 1 is also able to down-regulate the deposition of fibronectin by mesoderm cells grown on fibronectin and of epiblast cells grown on laminin, but up-regulate fibronectin deposition by mesoderm on laminin. Similar substratum-dependent changes are seen in laminin deposition, which is down-regulated in mesoderm on laminin and up-regulated in epiblast on laminin. No effect on laminin deposition is seen in either cell type grown on fibronectin. Expression of the fibronectin receptor is also down-regulated by TGF beta 1 in mesoderm cells grown on fibronectin, and this may explain the decreased deposition of fibronectin associated with these cells under these conditions. We suggest that these results are consistent with a reinforcing role for TGF beta 1 in the transformation that results in the emergence of mesoderm cells at gastrulation. This factor may also be involved in the maintenance of the fibroblastic phenotype of the mesoderm cells after their ingression, by effects on the expression of receptors for extracellular matrix and on the deposition of matrix by these cells during their early morphogenesis.

Animals↗
PubMed1991

Odontoma of the middle ear cleft.

Odontoma of the middle ear cleft is an unusual cause of conductive hearing loss. We report two cases and discuss the developmental mechanism by which this anomaly may occur. The differential diagnosis of calcified masses in the middle ear is also discussed.

Adult↗
PubMed1990

ADP-ribosylation of HMG proteins and its modulation by different effectors in the liver of aging rats.

The in vitro ADP-ribosylation of high mobility group (HMG) non-histone proteins and its modulation by spermine, butyrate, dexamethasone and 3-aminobenzamide were studied in the liver of young (14 weeks) and old (113 weeks) male rats. ADP-ribosylation of HMG 1 was similar in both ages, whereas that of HMG 2 and 14 decreased but HMG 17 increased in the old. HMG 1 was ADP-ribosylated to a greater extent in young but to a lower level in the old by different effectors except spermine which showed no influence in old age. ADP-ribosylation of HMG 2 was stimulated by spermine, butyrate and dexamethasone in old but only by spermine in young rats. Other effectors decreased the ADP-ribosylation of HMG 2 in young. The ADP-ribosylation of HMG 14 was stimulated by spermine in the old but that of HMG 17 was reduced by butyrate in young and by spermine in the old. Dexamethasone decreased the ADP-ribosylation of both HMG 14 and 17 in young, whereas this showed no change in old age. Aminobenzamide inhibited ADP-ribosylation of only HMG 2 in young but all HMGs except HMG 2 in the old. Such alteration in the ADP-ribosylation of HMG proteins may affect various cellular and nuclear functions of rat liver during aging.

Adenosine Diphosphate Ribose↗
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↗