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Biomedical subjects

S Iyer

Publications and source records attributed to S Iyer.

At least 91 records · Page 5Linked to original sources
PubMed1993

The impact of balloon angioplasty of coronary artery and/or vein bypass graft lesion(s) upon the survival of patients > or = 5 years after their last bypass surgery.

Data analyses of angioplasty patients, whose operative and angioplasty (PTCA) interval was > or = 5 years, were performed to determine if the site of PTCA (coronary artery (CA) and/or vein bypass graft (VG)) influenced longevity. PTCA was successful in 677/768 lesions (88%) (377/432 CA (87%), and 294/327 VGs (90%)) and resulted in clinical improvement in 280/322 patients (87%). Patients were stratified into those who underwent PTCA of a lesion(s) in a coronary artery only, a vein graft only, or in both a coronary artery and a vein graft. Survival, at 60 months, was adversely affected (P < 0.05) for VG (59%) in comparison to CA (86%) or CA + VG (86%) cohorts, which was reaffirmed by a Cox proportional hazard model. PTCA was effective in opening lesions in coronary arteries or vein grafts in patients whose last bypass surgery had occurred over 5 years previously; however, PTCA patients who only had a vein graft had a significantly diminished 5-year survival in comparison to the cohorts, who had a coronary artery lesion dilated, with or without an accompanying vein graft PTCA. Therefore, PTCA of isolated vein graft lesions may not be the best long-term therapeutic option for these patients; however, it may best serve patients, acutely and long-term, who have an amenable significant arterial lesion, whether or not an accompanying vein graft lesion is dilated.

Aged↗
PubMed1991

Angiographic follow-up and clinical outcome of 126 patients after percutaneous directional atherectomy (Simpson AtheroCath) for occlusive peripheral vascular disease.

Angiographic and clinical follow-up data were obtained in 115/126 patients who underwent directional atherectomy for peripheral vascular disease; of the 126, ten were excluded for appropriate reasons and one was lost to follow-up. Thus, 115/116 successful atherectomy patients (99%) had follow-up of 182/213 lesions (86%): 74 patients (64%) with angiography (mean time 5.4 mon), and 41 patients (36%) clinically. One hundred twenty-eight of 183 lesions (70%) had angiographic follow-up; the lesion recurrence as a stenosis or as an occlusion was 53%. Lesion distribution did not differ between angiography and clinical follow-up groups: nearly 85% were within the superficial femoral or popliteal arteries. Despite data stratification, angiographic follow-up indicated that patients after successful directional atherectomy, at a mean follow-up time of 5 mos, have more than a 50% lesion recurrence rate. Although directional atherectomy (Simpson AtheroCath) utilizing present techniques has excellent primary success and acceptable complication rates, angiographic follow-up statistics are bothersome.

Aged↗
PubMed1991

Acute angiographic and clinical outcome of high speed percutaneous rotational atherectomy (Rotablator).

Percutaneous rotational atherectomy (Rotablator), a high speed (greater than 100,000 RPM) rotational burr, was used successfully in 38 of 43 patients (88%) (mean age: 65 +/- 7 years) with 82 lesions (71 stenoses and 11 occlusions). The clinical indications were claudication (84%), nonhealing ulcer (7%), and renovascular hypertension (7%). Rotablation was successful in 78 of 82 lesions (95%): 68 of 71 (96%) stenoses (12 of 12 iliac, 11 of 11 femoral, 7 of 8 popliteal, 36 of 37 tibial, and 2 of 3 renal arteries; 60% of lesions were diffuse, i.e., greater than or equal to 4 cm in length), and 10 of 11 (91%) occlusions (5 of 6 femoral, 1 of 1 popliteal, 3 of 3 tibioperoneal, 1 of 1 brachial artery). The Rotablator significantly (p less than 0.001) reduced the arterial obstruction (stenoses: 85 +/- 11% to 12 +/- 12%); occlusions: 100% to 25 +/- 10%). The effective final burr size for arteries varied at 3.5-4.5 mm for renal, 3.0-3.5 mm for femoral, and 2.0-3.0 mm for brachial and tibial. Complications included gross hemoglobinuria without sequelae in 27 patients (63%), groin hematoma in 10 (23%), arterial spasm in 10 (23%), and arterial bypass in 2 (5%). The Rotablator was successfully used, without concomitant conventional balloon angioplasty, to open arterial lesions with excellent angiographic results in both diffuse and segmental peripheral vascular disease. There was gratifying patient clinical improvement.

Aged↗
PubMed1991

Retrograde intussusception as a complication of Roux-en-Y anastomosis.

We report a case of a serious complication of a Roux-en-Y reconstruction in which an antiperistaltic jejunojejunal intussusception created a strangulating intestinal obstruction. It is suggested that this complication may be an extreme form of the so-called Roux-en-Y stasis syndrome.

Anastomosis, Roux-en-Y↗
PubMed1990

Structure of 1,4-cubanediyldiammonium bis(trinitromethanide).

C8H12N2+.2CN3O6-, Mr = 436.27, monoclinic, C2/m, a = 14.298 (2), b = 8.408 (1), c = 7.354 (2) A, beta = 103.42 (2) degrees, V = 859.9 (5) A3, Z = 2, Dx = 1.68 g cm-3, lambda(Mo K alpha) = 0.71069 A (graphite monochromator), mu = 1.66 cm-1, F(000) = 448, T = 293 K, final R = 0.039 for 672 reflections with I greater than or equal to 3 sigma(I). The cubanediyldiammonium cation and trinitromethanide anion have 2/m and m crystallographic symmetries, respectively. The cation is linked to six trinitromethanide anions, three at each end, by a total of 12 N--H...O hydrogen bonds through the six cation H atoms. The cubane cage has a local threefold axis of symmetry along the long axis (N1...N1) of the cation and undergoes a large librational motion, 17 degrees r.m.s. amplitude, about this axis.

Bridged-Ring Compounds↗
PubMed1990

Isolation, synthesis, and evaluation of a series of indencarbazates as hypotensive agents.

Two indencarbazates, 1 and 2, were isolated from the sponge Cliona caribboea. These compounds were found to possess mild hypotensive activity. A series of analogues of 1 was synthesized in order to study the structure-activity relationship of this unique class of compounds. A variety of structural changes did not result in a consistent pattern of biological activity.

Animals↗
PubMed1986

Red pigment in Bacillus megaterium spores.

Bacillus megaterium QM B1551 spores contained a unique red pigment in their membranes that was not found in other species. This red pigment, presumably a carotenoid, was synthesized about the time of dipicolinic acid synthesis during sporulation and was associated with the forespores. A yellow pigment was synthesized during sporulation in rich medium and was found in the mother cell compartment. Although the yellow pigment was also associated with spores, it could be removed by two different extraction procedures without impairing germination; it was absent when sporulation occurred in a minimal medium. Although the yellow pigment of the mother cell appeared to be dispensable, the red pigment may serve a more critical function, such as membrane stabilization.

Bacillus megaterium↗
PubMed1986

Serospecific antigens of Legionella pneumophila.

Serospecific antigens isolated by EDTA extraction from four serogroups of Legionella pneumophila were analyzed for their chemical composition, molecular heterogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunological properties. The antigens were shown to be lipopolysaccharides and to differ from the lipopolysaccharides of other gram-negative bacteria. The serospecific antigens contained rhamnose, mannose, glucosamine, and two unidentified sugars together with 2-keto-3-deoxyoctonate, phosphate, and fatty acids. The fatty acid composition was predominantly branched-chain acids with smaller amounts of 3-hydroxymyristic acid. The antigens contain periodate-sensitive groups; mannosyl residues were completely cleaved by periodate oxidation. Hydrolysis of the total lipopolysaccharide by acetic acid resulted in the separation of a lipid A-like material that cross-reacted with the antiserum to lipid A from Salmonella minnesota but did not comigrate with it on sodium dodecyl sulfate gels. None of the four antigens contained heptose. All of the antigen preparations showed endotoxicity when tested by the Limulus amebocyte lysate assay. The results of this study indicate that the serogroup-specific antigens of L. pneumophila are lipopolysaccharides containing an unusual lipid A and core structure and different from those of other gram-negative bacteria.

Antigens, Bacterial↗
PubMed1986

Characterization of human interferon species using gel extraction and monoclonal antibodies: implications on clinical use of interferon preparations.

Human interferons from various sources have been characterized using sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by electrotransfer onto nitrocellulose and reaction with specific polyclonal and monoclonal antibodies. When gel slices were extracted, alpha-interferon subspecies possessed antiviral activity predominantly in the 18.6-19.7K region bands, the beta-interferon in the 22.1K band, and gamma-interferon in the 16.5-18.0K bands. Three of the monoclonal antibodies (Ab 138, Ab 126, Ab 098) reacted with a characteristic triplet of biologically active bands (18.6K, 19.1K, 19.7K) obtained using the Namalwa cell interferons, while two (Ab 194 and Ab 232) reacted only with the 18.6K band and Ab 523 reacted with the 19.7K band. With the human leukocyte interferons, Ab 098, Ab 194, and Ab 232 reacted with the active 18.6K band. The Ab 138, Ab 126, and Ab 523 reacted specifically with certain lower molecular weight active bands (13K region). A comparison of the antiviral activity and reactivity towards monoclonal and polyclonal antibodies presents a differentiation of the subspecies of interferons in the wide array of closely related proteins in interferon preparations packaged for clinical use.

Antibodies, Monoclonal↗
PubMed1978

Portacaval shunt with arterialization of the portal vein by means of a low flow arteriovenous fistula.

A new operative technique was designed combining an end-to-side portacaval shunt with arterialization of the intrahepatic portal vein by means of a saphenous vein graft between the right gastroepiploic artery and the stump of the portal vein. The objective of this operation is to perfuse the hepatic portion of the portal vein with a low volume of arterial blood to ameliorate the adverse metabolic consequences of portosystemic decompression. The procedure was performed upon 18 patients with one operative mortality. The mean follow-up period is 15.4 months. The benefits of this operation are evident in the prevention of hepatic decompensation and avoidance of encephalophy, thus permiting unrestricted protein intake. The operation is well tolerated, and the operative mortality appears to be less than that following conventional shunting procedures.

Adult↗