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Biomedical subjects

A Saxena

Publications and source records attributed to A Saxena.

At least 217 records · Page 12Linked to original sources
PubMed1993

Echocardiographic diagnosis of aneurysm of the sinus of Valsalva.

Echocardiographic and Doppler data of 62 patients with ASOV are presented. Catheterization and angiography were performed in 38 cases and surgery in 25 of the 38. The origin of these aneurysms was the RCS in 56 cases, NCS in 5, and LCS in 1 case. Seven had unruptured aneurysms, 6 rising from RCS dissected into the ventricular septum, producing heart block in 4, AR in 5, mitral regurgitation in 1; 1 aneurysm rising from the LCS was asymptomatic. In other cases (n = 55) the aneurysm had ruptured into one of the cardiac chambers. Thirty-two of the 50 RCS aneurysms ruptured into the RVOT, 13 into the RV cavity, 2 into the RA, and 3 into the LV. Of the 5 NCS aneurysms, (3 ruptured into the RA, 1 into the RV, and 1 into both the RA and RV. Associated VSD was identified in 16 (25.8%) of 62 cases. All of these patients had RCS aneurysms that ruptured into the RVOT. Echocardiography missed VSD in three cases that at surgery were found to have VSD. AR was found in 34 of 62 cases. Echocardiography picked up discrete subaortic stenosis in two cases but missed subvalvar PS in 2 of the 3 cases. A detailed echocardiographic study (two-dimensional, Doppler, and color flow imaging) is accurate in the diagnosis of ASOV, in the identification of its site of origin and rupture, and in the evaluation of the associated defects; in the vast majority of cases, it can totally supplant the need for angiography.

Adolescent↗
PubMed1993

Echocardiographic diagnosis of total anomalous pulmonary venous connection.

Over a 7-year period, 110 of 35,000 echocardiographic cases were diagnosed to have total anomalous pulmonary venous connection (TAPVC). Ages ranged from 7 days to 38 years (male 62, female, 48). In 60 cases the diagnosis was confirmed by angiography (n = 47) and/or surgery (n = 50). In 13 cases angiography was not performed; surgery was performed on the basis of echocardiographic diagnosis. Diagnosis of TAPVC was correctly made in all of the 60 confirmed cases. Drainage sites were correctly identified by echocardiography in 58 (96.7%) of these 60 cases. Of the five cases of mixed TAPVC, the second drainage site was missed by echocardiography in two cases. Of the 110 cases the drainage sites were as follows: supracardiac 70, cardiac 30, infracardiac 5, and mixed variety 5. Seventeen cases had Doppler echocardiographic evidence of obstruction along the course of the anomalous vein. The continuous wave Doppler signal for tricuspid regurgitation was present in 14 of 47 catheterized patients, and catheterization-measured peak pulmonary artery systolic pressure correlated well with that derived by Doppler study (r = 0.96, p = 0.001). Additionally, 17 patients had other cardiac anomalies that were correctly diagnosed by echocardiography. Combined two-dimensional and Doppler echocardiography is accurate in the diagnosis of TAPVC, identification of the site of drainage, presence of obstruction, and assessment of pulmonary arterial hypertension and other associated anomalies.

Adolescent↗
PubMed1993

Immunochemical characterization of anti-acetylcholinesterase inhibitory monoclonal antibodies.

Monoclonal antibodies (mAbs) were prepared against native or DFP-inhibited Torpedo californica acetylcholinesterase and native or DFP-, MEPQ-, and soman-inhibited fetal bovine serum acetylcholinesterase. The cross reactivity of these antibodies with acetylcholinesterases from various species and their ability to inhibit catalytic activity were determined. Eight antibodies were found to inhibit catalytic activity of either Torpedo or fetal bovine serum enzyme. In all cases the antibodies bound to the native form of the enzymes and in some cases even to the denatured form. None of the antibodies recognized human or horse serum butyrylcholinesterase. Sucrose density gradient centrifugation of enzyme-antibody complexes provided two types of profiles, one with multiple peaks, indicating numerous complexes between tetrameric forms of the enzyme, and the other with single peaks, demonstrating complex formation within the tetrameric form. Different antibodies appeared to interact with slightly different regions, but in all cases the binding encompassed the peripheral anionic site. Decrease in catalytic activity of the enzyme was most likely caused by conformational changes in the enzyme molecule resulting from interaction with these mAbs.

Acetylcholinesterase↗
PubMed1993

Epilepsy and bathtub drowning. Important neuropathological observations.

Drowning is a well-recognized cause of death in persons with epilepsy. Investigation of bathtub drowning is often not straightforward. We report three cases of bathtub water drowning of patients with neuropathological bases for seizures. The importance of neuropathological examination is discussed. A high index of suspicion is required for all cases of bathtub-related death, even in the absence of history of previous seizure disorders. Neuropathological examination must be performed to look for anatomical lesions associated with seizures. Identification of these findings could be very helpful in ruling out homicide or suicide as the cause of death in bathtub drownings.

Adult↗
PubMed1993

Device use patterns and clinical outcome of implantable cardioverter defibrillator patients with moderate and severe impairment of left ventricular function.

The beneficial effects of implanted cardioverter defibrillator (ICD) therapy in patients with malignant ventricular tachyarrhythmias and variable degrees of left ventricular (LV) dysfunction are debated. ICD use and patient survival were examined in 128 patients with malignant ventricular arrhythmias and moderate or severe LV dysfunction. Group I included 64 patients with moderate LV dysfunction (LV ejection fraction of > 30%) and group II, 64 patients with severe LV dysfunction (LV ejection fraction of < or = 30%). Follow-up period ranged from 1 to 78 months. The two groups were similar in age, incidence of coronary artery disease and presenting arrhythmia. The mean LV ejection fraction in group I was 44% +/- 8% and group II was 22% +/- 5% (P < 0.0001). At 4 years of follow-up, 66% of patients from group I and 62% from group II (P = NS) had ICD activation for presumed ventricular tachyarrhythmia. Survival was calculated using actuarial analysis. Arrhythmic or sudden death mortality at 4 years of follow-up was 4% in group I and 7% in group II (P = NS). Cardiac mortality was for group I, 7% (P < 0.05), 12% (P < 0.01), 15% (P < 0.01), and 15% (P < 0.01) for follow-up years 1, 2, 3, and 4, respectively. For group II, cardiac mortality was 27%, 36%, 41%, and 41% for follow-up years for 1, 2, 3, and 4, respectively. The majority of cardiac deaths in both groups was observed in the first 2 years of follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

Expression of the vascular permeability factor/vascular endothelial growth factor gene in central nervous system neoplasms.

Expression of the vascular permeability factor/vascular endothelial growth factor (VEGPF) gene was investigated in human central nervous system (CNS) neoplasms and normal brain. Adsorption of capillary permeability activity from human glioblastoma multiforme (GBM) cell conditioned medium and GBM cyst fluids by anti-VEGPF antibodies demonstrated that VEGPF is secreted by GBM cells and is present in sufficient quantities in vivo to induce vascular permeability. Cloning and sequencing of polymerase chain reaction-amplified GBM and normal brain cDNA demonstrated three forms of the VEGPF coding region (567, 495, and 363 nucleotides), corresponding to mature polypeptides of 189, 165, and 121 amino acids, respectively. VEGPF mRNA levels in CNS tumors vs. normal brain were investigated by the RNase protection assay. Significant elevation of VEGPF gene expression was observed in 81% (22/27) of the highly vascular and edema-associated CNS neoplasms (6/8 GBM, 8/8 capillary hemangioblastomas, 6/7 meningiomas, and 2/4 cerebral metastases). In contrast, only 13% (2/15) of those CNS tumors that are not commonly associated with significant neovascularity or cerebral edema (2/10 pituitary adenomas and 0/5 nonastrocytic gliomas) had significantly increased levels of VEGPF mRNA. The relative abundance of the forms of VEGPF mRNA was consistent in tumor and normal brain: VEGPF495 > VEGPF363 > VEGPF567. In situ hybridization confirmed the presence of VEGPF mRNA in tumor cells and its increased abundance in capillary hemangioblastomas. Our results suggest a significant role for VEGPF in the development of CNS tumor neovascularity and peritumoral edema.

Base Sequence↗
PubMed1993

Close proximity of c-erbA2 and c-erbA-beta genes on the short arm of chromosome 3.

The common loss region on the short arm of chromosome 3 (3p) in human breast tumors harbors two members of the c-erbA receptor gene family, c-erbA2 and c-erbA-beta, both of which recognize a BamHI polymorphism in human genomic DNA. Analysis of lymphocyte DNAs from 50 normal individuals and lymphocyte DNAs from 50 normal individuals and lymphocyte and tumor DNAs from 116 breast cancer patients revealed identical genotypes (a/a, b/b or a/b) for both probes. Furthermore, deletion of the same allele (a/- or -/b) of c-erbA2 and c-erbA-beta was detected in 25% of the 66 breast tumors from patients with constitutionally heterozygous genotypes for both genes. No sequence homology was detected between the c-erbA2 and c-erbA-beta genes, suggesting a physical linkage between these two genes. Digestion of the genomic DNA with combinations of restriction enzymes and hybridization with c-erbA2, which is a genomic fragment, and c-erbA-beta, which is a cDNA clone, provide evidence that c-erbA2 and a region of the c-erbA-beta gene are physically contiguous on the short arm of chromosome 3 and are separated by no more than 1.8 kb of DNA sequences.

Breast Neoplasms↗
PubMed1993

Larvicidal and chemosterilant activity of Annona squamosa alkaloids against Anopheles stephensi.

Alkaloids isolated from Annona squamosa have shown larvicidal growth-regulating and chemosterilant activities against Anopheles stephensi at concentrations of 50 to 200 ppm. Adults exposed as larvae to different treatments showed reduced fecundity and fertility in females. Mortality in the larvae, pupae and adults produced about a 52-92% decrease in the laboratory experiment. The total developmental period was slightly reduced from the control. Treatment with the alkaloids had a significant effect on the mortality, emergence and reproductive physiology of An. stephensi.

Alkaloids↗
PubMed1992

Evidence for the involvement of a potential second tumor suppressor gene on chromosome 17 distinct from p53 in malignant astrocytomas.

Molecular analysis of malignant astrocytomas demonstrated three distinct groups of tumors with chromosome 17p abnormalities, which include (a) deletion of the p53 locus (17p13.1) and mutations in the remaining allele, (b) deletion of the p53 locus but no detectable mutations in the remaining allele, and (c) deletions not including the p53 locus but mutations in one of the alleles. Furthermore, deletion mapping analysis demonstrated allelic loss of genes distal to D17S28/D17S5 markers (17p13.3) in group C tumors. The loss of heterozygosity of genes on chromosome 17 without detectable mutation (group B) or deletion (group C) in the p53 gene implies the presence of a second tumor suppressor gene in the telomeric region of 17p, the homozygous functional inactivation of which may play a role, either alone or in conjunction with p53, in the initiation and/or progression of astrocytic neoplasms.

Base Sequence↗
PubMed1992

Amplification and/or overexpression of platelet-derived growth factor receptors and epidermal growth factor receptor in human glial tumors.

Analysis of genomic organization and expression of platelet-derived growth factor receptors (PDGFR) and epidermal growth factor receptor (EGFR) in human malignant gliomas showed amplification and overexpression of both receptors in distinct subsets of tumors. Amplification of the alpha PDGFR was detected in 4 of 50 glioblastomas (8%). EGFR was amplified in 9 of the 50 tumors (18%). Western blot analysis showed elevated expression of alpha PDGFR and EGFR proteins in 4 (24%) and 3 (18%), respectively, of 17 tumor specimens analyzed. Increased production of alpha PDGFR as well as EGFR proteins was observed in the presence or absence of gene amplification. Three of the 4 tumors with elevated levels of alpha PDGFR also overexpressed the beta PDGFR, which was present as a single copy gene in all 50 tumors analyzed. Our findings suggest that the amplification and/or overexpression either of EGFR or of the alpha PDGFR along with the coordinate overexpression of the beta PDGFR can contribute to the malignant phenotype of distinct subsets of human glioblastoma.

Blotting, Western↗
PubMed1992

Biological actions of monoclonal antibodies to bovine lutropin receptor.

Monoclonal antibodies (Mabs) were produced against bovine Lutropin receptor (LH-R). Antibodies were detected by an enzyme linked immunosorbant assay (ELISA). Hybridomas were subcloned to achieve monoclonality. Ascites were developed in Balb/c mice. Hybridoma supernatants were purified by ammonium sulfate precipitation and chromatography on hydroxylapatite columns. LH-R antibodies showed upto 50% inhibition of 125I-labeled hCG binding to bovine luteal cell membranes and up to 80% inhibition of testosterone production by hCG stimulated mouse Leydig cells. LH-R antibodies were predominantly IgM isotype. Purified antibodies showed a 78-kDa band, in SDS-PAGE, as the heavy chain of the immunoglobulin. LH-R antibodies were localized specifically in the thecal and luteal cells of the rat ovaries as well as in the Leydig cell of mouse testes. Injections of the LH-R antibody caused a constant estrus in normal rats. One month after the cessation of the injections the animals returned to normal estrus cycle and fertility. Pregnant mice injected with LH-R antibodies produced only 3 viable pregnancies and 10 pups, as compared to 8 pregnancies and 45 pups born to normal controls. LH-R antibodies also caused, approximately, a 50% reduction in testosterone production in normal male rats. These observations indicate a high degree of specificity of the Mab to LH-R and their potential in studies on gonadal function.

Animals↗
PubMed1992

Phenytoin reduces suxamethonium-induced myalgia.

A prospective, randomised trial was undertaken in 60 healthy adults to determine the efficacy of intravenously administered phenytoin in doses of 5 mg.kg-1 for the prevention of suxamethonium-induced fasciculations, a rise in serum K+ and myalgia. This was compared with tubocurarine pretreatment and no pretreatment (control group). Phenytoin pretreatment significantly reduced myalgia from 45% (nine patients) in the control group to 10% (two patients) (p less than 0.05). It also decreased the duration and mean intensity of fasciculations. Incidentally, phenytoin was also found to decrease significantly mean serum Na+ levels (p less than 0.001) both at 5 and 20 min after administration. Tubocurarine pretreatment (3 mg) resulted in a significant decrease in fasciculations, but myalgia, which occurred in five patients, remained the same. No significant correlation was found between muscle fasciculations, postoperative myalgia and K+ changes, but patients with myalgia had a significant decrease in mean serum Na+ levels at 5 and 20 min after suxamethonium (p less than 0.01).

Adult↗