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Biomedical subjects

S K Tyagi

Publications and source records attributed to S K Tyagi.

13 recordsLinked to original sources
PubMed2000

Transcranial Doppler evaluation of blood flow velocity changes in basal cerebral arteries in cerebral AVMs following embolisation and surgery.

Blood flow velocities in the basal cerebral arteries were evaluated in 41 patients with supratentorial arteriovenous malformation (AVM), using a transcranial doppler 64-B instrument. The AVM was surgically excised in 20 patients and embolised in 21 patients. Blood flow velocities in feeding basal cerebral arteries were found markedly decreased in both the groups, at 24 hours after intervention. On follow up study at 3 months, blood flow velocity in feeding cerebral artery was found to be increased in 47 percent of patients who were embolised, but remained normal in all the patients who underwent surgery.

Cerebral Arteries↗
PubMed1997

Novel gene delivery to liver cells using engineered virosomes.

We have demonstrated for the first time that the reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) are efficient vehicles for the delivery of foreign genes specifically into human hepatoblastoma cells (HepG2) in culture. The membrane fusion-mediated entry of CAT (chloramphenicol acetyl transferase) gene into the cells was confirmed and the amount delivered to various subcellular fractions was quantitated. The dose dependence and kinetics of expression of biologically active CAT protein in HepG2 cells was measured. The CAT expression level in F-virosome-mediated delivery was significantly higher than that of Lipofectin or liganded proteo-liposome-mediated gene transfer. This kind of targeted delivery by means of membrane fusion induced by viral envelope glycoprotein may have wide applications to various gene transfer strategies both in vitro and in vivo.

Animals↗
PubMed1997

A 45,000-M(r) glycoprotein in the Sendai virus envelope triggers virus-cell fusion.

Sendai virus envelopes devoid of hemagglutinin-neuraminidase but containing the fusion protein (F-virosomes) were prepared. F-virosomes exhibited discernible serine protease activity at neutral pH. Electrophoretic analysis of the protein profile of the F-virosomes under nonreducing conditions, by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing, led to the identification of a previously unknown glycoprotein with a relative molecular weight of 45,000 (45K protein) associated with the F protein. The identity of the 45K protein, as distinct from F protein, was established by Western blot analysis with F- and 45K-specific antibodies. This 45K protein forms a nexus with the F protein through noncovalent hydrophobic interactions, as proved by its sensitivity to urea treatment, and it is essential for the proteolytic activity of the F-virosomes as well as for the fusion of the viral envelope with host cell membrane. N-terminal sequence analysis (first 11 amino acids) of this protein showed strong homology (> 90%) to flavivirus NS3 serine proteases but no similarity to any of the Sendai viral proteins. On the basis of the N-terminal sequence, oligonucleotides were designed corresponding to the sense and antisense DNA sequences. Dot blot hybridization and primer extension with these oligonucleotides with the viral and the host genome confirmed the host origin of this protein. Further, the limited proteolytic digestion of the target membrane resulted in significant inhibition of viral fusion with it. On the basis of these results, we postulate a model for the molecular mechanism of F protein-induced membrane fusion, which may provide a rationale for other paramyxoviruses.

Animals↗
PubMed1982

Haematological and biochemical characteristics of Heteropneustes fossilis under the stress of Congo Red (diphenyl disazo binaphthionic acid).

The effects of the sublethal concentration (0.012%) of Congo Red on Heteropneustes fossilis were studied after 30 days exposure. The RBC count haemoglobin (Hb)% and PCV decreased significantly. The total WBC count, MCV, MCH, and MCHC showed a significant increase. Serum calcium, serum cholesterol and blood urea nitrogen (BUN) were significantly elevated, whereas serum phosphorus was significantly reduced. The activities of serum alkaline phosphatase (AlPase), acid phosphatase (AcPase). RNase, GOT, GPT and amylase were also significantly elevated. The possible reasons for these changes are discussed.

Animals↗
PubMedDate not supplied

Evidence for activation of cellular immune responses in patients with acute hepatitis E.

INTRODUCTION: Although acute hepatitis E virus (HEV) infection is known to induce IgM and IgG humoral host immune responses, little is known about occurrence of cellular responses in this infection. We looked for evidence of lymphocyte sensitization to HEV peptides in patients with acute HEV infection. METHODS: peripheral blood lymphocytes were obtained from patients with acute hepatitis E and healthy controls. Proliferation of these lymphocytes in the presence of each of seven peptides with amino acid sequences corresponding to open reading frames 2 and 3 proteins of HEV (3 and 4 peptides, respectively) were studied; no peptide was added to control wells. Proliferative responses with stimulation indices exceeding 3.0 were taken as positive. RESULTS: More patients showed reactivity to two or more HEV peptides than did controls (11/21 vs 5/22, p<0.05). Reactivity to one peptide corresponding to open reading frame 2 of HEV was more frequent in patients than in controls (7/21 vs 1/22, p<0.05). CONCLUSION: Our results show that lymphocytes of patients with acute hepatitis E show sensitization to HEV peptides. This may have significance in understanding the pathogenetic mechanisms of liver injury in this infection.

Acute Disease↗
PubMedDate not supplied

A study of hepatopulmonary syndrome among patients of cirrhosis of liver and portal hypertension.

OBJECTIVES: Hepatopulmonary syndrome consists of a triad of hepatic dysfunction and/or portal hypertension, intrapulmonary vascular dilatations and hypoxemia. A study of hepatopulmonary syndrome among patients of cirrhosis of liver and portal hypertension was undertaken. METHODS: Thirty patients participated in this study. The diagnosis of cirrhosis of liver was confirmed by liver biopsy. Arterial blood gas analysis, pulmonary function tests, two-dimensional transthoracic air contrast echocardiography were undertaken in all the patients. Those patients in whom contrast echocardiogram showed intrapulmonary vascular dilatations were classified as the positive group while others were labelled as the negative group. RESULTS: Ten patients (33.33%) had a positive contrast echocardiogram; five (16.67%) of them were found to have PaO2<70 mmHg and were qualified for the diagnosis of hepatopulmonary syndrome (HPS); and other five (16.67%) with PaO2>70 mmHg were diagnosed as intrapulmonary dilatations syndrome (IPVDS). Five patients of HPS revealed significant P(A-a)O2 gradient and intrapulmonary shunts of moderate severity computed by a/A ratio. Cyanosis (p=0.001), clubbing (p=0.009) and orthodeoxia (p=0.0024) were significantly commoner in the five patients of hepatopulmonary syndrome. Presence of spider naevi was significantly related with the presence of intrapulmonary vascular dilatations. CONCLUSIONS: The study results showed presence of hepatopulmonary syndrome and intrapulmonary vascular dilatation syndrome among patients of portal hypertension. The presence of cyanosis, clubbing and orthodeoxia were found to be suggestive indicators of hepatopulmonary syndrome. Even though not very specific, spider naevi were found to be a useful clinical indicator for the presence of intrapulmonary vascular dilatations.

Adult↗
PubMedDate not supplied

Portopulmonary hypertension in a patient of autoimmune hepatitis.

A 35-year-old women presented with breathlessness and features suggestive of pulmonary hypertension. Further investigations revealed that she had autoimmune hepatitis and both portal and pulmonary hypertension. Pertinent literature is reviewed.

Adult↗