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Biomedical subjects

G W Smith

Publications and source records attributed to G W Smith.

At least 145 records · Page 8Linked to original sources
PubMed1983

The rabbit isolated arterially perfused intestinal segment preparation: a model for vascular dopamine receptors.

A simple and inexpensive method for the evaluation in vitro of the effects of compounds on postjunctional vascular dopamine (DA) receptors is described. The rabbit isolated perfused K+-contracted mesenteric and ileal vasculature dilates in response to DA, DA receptor agonists, and papaverine. Responses to DA receptor agonists, but not those to papaverine, can be selectively antagonised by cis-(Z)-flupenthixol (pA2 8.5), yet remain unaffected by sulpiride. Comparisons with other models of vascular DA receptors have been made.

Animals↗
PubMed1983

Long-term prophylaxis of urinary infections in women: comparative trial of trimethoprim, methenamine hippurate and topical povidone-iodine.

We randomized 64 patients with a history of recurrent urinary tract infections among 3 regimens of long-term (1 year) prophylactic treatment: 20 were given 100 mg. trimethoprim at night, 25 received 1,000 mg. methenamine hippurate every 12 hours and 19 were asked to cleanse the perineum (especially the periurethral area) twice daily with povidone-iodine solution. The progress of patients in terms of urinary symptoms and/or bacteriuria, changes in periurethral flora, side effects, and hematological and biochemical profiles was followed at regular intervals. All treatments were effective in reducing the incidence of symptomatic attacks when compared to the 12 months immediately before therapy and there was little to choose between the individual regimens on this account. However, trimethoprim was tolerated better than were the other 2 treatment regimens. In the group given trimethoprim most of the breakthrough infections (71.4 per cent) that occurred were caused by trimethoprim-resistant organisms (usually Escherichia coli), while in the other 2 groups the incidence of trimethoprim-resistant organisms causing infection was low (2.7 per cent). Treatment with trimethoprim reduced significantly the periurethral colonization of Escherichia coli.

Administration, Topical↗
PubMed1983

Percutaneous transhepatic management of complex biliary problems.

A series of 27 patients with complex biliary problems secondary to previous biliary operations is presented. The patients are divided into two groups: (1) patients with acute perioperative biliary problems; all had biliary leak with abscess, biliary cutaneous fistula, and/or stricture following cholecystectomy or common duct exploration and (2) patients with chronic postoperative biliary problems; all had previous repair of biliary stricture or injuries with late stricture formation. Early management of all patients included placement of a percutaneous biliary stent. Abscesses were drained operatively, and biliary leaks or fistulas were allowed to close spontaneously. Jaundice and cholangitis were allowed to resolve. Following stabilization, management of stricture, if present, was addressed. Eight acute patients had strictures, of which four were partial and three were dilated percutaneously. Four were complete and required operative repair. All 12 chronic patients had strictures, of which six were partial and successfully managed with percutaneous dilatation. Four patients also had common duct stones which were successfully crushed percutaneously. The authors conclude that percutaneous transhepatic drainage offers significant advantages in the early stabilization and treatment of patients with complex biliary problems, and that partial strictures of the biliary tree may be managed successfully by percutaneous dilatation.

Adolescent↗
PubMed1983

Biological consequences of neuraminidase deficiency in Newcastle disease virus.

A second-step revertant (L1) of a temperature-sensitive mutant (C1) of Newcastle disease virus agglutinated erythrocytes normally but had less than 3% of the wild-type (strain AV) levels of neuraminidase activity. Revertant L1 had seven times more virion-associated N-acetylneuraminic acid (NANA) than strain AV. NANA residues on purified virions were specifically labeled with periodate and tritiated borohydride. Analyses of radiolabeled L1 virions on sodium dodecyl sulfate-polyacrylamide gels showed that most of the virion-associated NANA was in a high-molecular-weight component with an electrophoretic mobility different from that of any known viral protein. NANA was also detected in molecules with the electrophoretic mobility of the viral glycoproteins HN and F1. Revertant L1 had a twofold lower rate constant of attachment to HeLa cells than that of the wild-type. Treatment of L1 virions with Vibrio cholerae neuraminidase removed the excess NANA and returned L1 attachment kinetics to normal. Revertant N1, which has 10-fold more neuraminidase activity than L1, penetrated host cells at the same rate as L1. L1 was impaired in elution from erythrocytes. Removal of virion-associated NANA exacerbated this defect. Despite a small disadvantage in attachment and a major defect in elution relative to strain AV, revertant L1 enjoyed a slight advantage over the wild-type during a single reproductive cycle in cultured chicken embryo cells.

Animals↗
PubMed1983

Serologic testing of badgers to monitor plague in southwestern Idaho.

Serologic testing of badgers (Taxidea taxus) was used to monitor plague (Yersinia pestis) in a Townsend ground squirrel (Spermophilus townsendi) population in 10,000 ha of the Snake River Birds of Prey Study Area, Idaho. Eighty-six percent of the 294 sera tested in 1975 and in 1976 were positive. Significantly fewer (72%) seropositives occurred in 1977. Seasonal changes in the percentage of seropositives and the decline in 1977 were probably due to the phenology of the Townsend ground squirrel and the proportion of that species in the badger's diet. Eight Townsend ground squirrels found dead had positive bacteriologic tests for plague; however, a high mortality in the ground squirrel population was not observed. Food habits and movement patterns of badgers made them ideal for documenting the geographical and temporal characteristics of the plague focus.

Animals↗
PubMed1983

Long-term results of aortoiliac angioplasty.

Results of percutaneous transluminal angioplasty of 141 iliac arteries in 112 patients are reported, with a follow-up period extending to 36 months. Initial technical success was achieved in 95.7%, 1-year patency in 91.3%, and accumulated 2- and 3-year patency in 89%. The role of outflow disease and ankle:arm index measurement and the importance of eliminating or significantly reducing the intra-arterial pressure gradients are discussed.

Adult↗
PubMed1983

Immune complexes in normal subjects.

Immune complex (IC) levels were measured in normal subjects using the C1q solid phase, C1q deviation, C1q binding and polyethylene glycol precipitation assays. Significant changes in IC levels were seen in normals with each of the assays but the pattern of variation was not consistent between assays or subjects or in the same subject from day-to-day. There were no consistent changes with meals, time of day, exercise or the prior administration of prednisone. Low levels of IC appear to be normal in plasma but the variation in IC levels is not explained. Normal IC may well comprise mixtures of non-specific immunoglobulin aggregates, rheumatoid factor-immunoglobulin complexes, idiotype-anti-idiotype complexes as well as specific antibody complexes with antigens from food, infective agents and other sources.

Adult↗
PubMed1983

Circulating immune complexes in myocardial infarction.

Thirty-one patients with proven acute myocardial infarction (MI) were studied prospectively at the time of admission to hospital and at 3, 7 and 18 days using 4 immune complex (IC) assays. Each assay showed an increased incidence of IC activity in MI with 76% of patients being positive in at least 1 assay on one or more of the sampling days. A positive IC assay did not show a significant correlation with cardiac failure, pericarditis, post MI syndrome or previous infarction. The presence of IC was found to correlate with serum C-reactive protein (CRP), serum enzymes and ESR and suggested that complexed CRP or other acute phase proteins may account for some of the IC activity found with less specific assays. The measurement of IC levels in MI has not proved helpful in the diagnosis, management or prediction of outcome in this disorder.

Antigen-Antibody Complex↗
PubMed1983

Endorectal pull-through operation in adults after colectomy and excision of rectal mucosa.

Ileal endorectal pull-through can be performed in adults after abdominal colectomy and excision of rectal mucosa. The procedure requires a painstaking dissection of the mucous membrane of the rectum to ensure cure of the polyposis or ulcerative colitis for which it is carried out. Some cases of ulcerative colitis are inappropriate for this dissection, and Crohn's disease prohibits the use of this operation. Fifteen operations in adults are described herein. Certain technical maneuvers have been of help to us and these are described. We have favored a diverting ileostomy maintained for 3 months. A pouch, positioned in the rectum, has hastened the return toward normal control. Sphincter control and responses have been uniformly good. Dilatations and sphincter exercises are routinely employed. Strictures are not rare but are amenable to correction by digital stretching.

Adolescent↗
PubMed1982

Percutaneous transluminal angioplasty as an adjunct to the surgical management of peripheral vascular disease.

Percutaneous transluminal angioplasty (PTA) was performed as an adjunct to an operation in 43 patients with peripheral arterial insufficiency. This represents 26% of patients undergoing PTA over the past 44 months. In 23 patients PTA was done in conjunction with planned vascular reconstruction. It was successful in all 23 patients, and patency of the vascular graft was maintained in 22 patients during a mean follow-up period of nine months. Fourteen patients had PTA after operation. It was successful in 13 of them, and vascular patency was maintained in all 13 during a mean follow-up period of four months. Six patients had PTA prior to a distal amputation or a skin graft. All healed promptly. The overall initial success rate of PTA was 98%, the complication rate was 2%, with a late failure rate of 2%. It is concluded that PTA is a valuable adjunct to vascular surgery to improve inflow or outflow for bypass grafts, to reduce the extent of the operation in poor risk patients, to facilitate the healing of distal amputations, and to manage late graft stenosis.

Adult↗
PubMed1982

Nitrogenase Activity Associated with Halodule wrightii Roots.

Nitrogen fixation (acetylene reduction) associated with roots of the seagrass Halodule wrightii was measured offshore near Beaufort and Moorhead City, N.C. Rates of acetylene reduction were higher in aerobic than in anaerobic assays and were linear for up to 5 days. The temperature range for acetylene reduction was 15 to 35 degrees C with a maximum activity at 35 degrees C. Nitrogenase activity was shown to vary seasonally with highest activities occurring during warmer summer months (23 mug of N(2) fixed per m per day). At in situ temperature, nitrogenase activities associated with surface-sterilized and non-surface-sterilized roots were similar. One morphological bacterial type was isolated from surface-sterilized roots and identified as Klebsiella pneumoniae type 4B.

Journal Article↗
PubMed1982

Revertant analysis of a temperature-sensitive mutant of Newcastle disease virus with defective glycoproteins: implication of the fusion glycoprotein in cell killing and isolation of a neuraminidase-deficient hemagglutinating virus.

Biological and molecular properties of a temperature-sensitive mutant (C1) of Newcastle disease virus and its revertants were analyzed. C1 exhibited three temperature-sensitive alterations (plaque formation, virion assembly, and cytopathogenicity) and several defects which were also present at the permissive temperature. C1 virions contained low amounts of hemagglutinin-neuraminidase glycopeptides and consequently were deficient in hemagglutinating and neuraminidase activities. These virions also contained defective fusion glycoproteins which rendered them poorly hemolytic and slow to penetrate cultured chicken embryo cells. The biological activities of the membrane glycoproteins were recovered sequentially in a series of plaque-forming revertants. The coreversion of hemolysis, membrane-penetrating activities, and cytopathogenicity in the first-step revertant (S1) suggested that fusion glycoproteins were major contributors to cellular destruction. This revertant also provided evidence of a role for fusion glycoproteins in virion assembly. From S1 we isolated a large-plaque-forming revertant (L1) that assembled wild-type amounts of biologically active hemagglutinin-neuraminidase glycoproteins into virions. Although it was normal for hemagglutination, L1 had less than 3% of the neuraminidase activity of the wild type, demonstrating that these two activities can be uncoupled genetically. The neuraminidase deficiency of L1 did not impair its virulence in ovo or its reproduction in cultured cells.

Animals↗
PubMed1982

Hemodynamic measurements in the evaluation and follow-up of transluminal angioplasty of the iliac and femoral arteries.

Intra-arterial pressure measurements and ankle pressure indices (determined by Doppler ultrasound) were used to evaluate the hemodynamic response after transluminal angioplasty of the iliac and superficial femoral arteries. Intra-arterial pressure was the best determinant of the end point and technical success of the procedure, while improvement in the ankle pressure index was a good predictor of clinical success. Patients with clinical improvement had a significant increase in ankle pressure regardless of the status of peripheral runoff, while those without improvement did not; they demonstrated impaired distal runoff and required further surgical intervention. Peripheral Doppler pressures also provided a convenient noninvasive method of long-term follow-up.

Angioplasty, Balloon↗
PubMed1982

Renin and aldosterone at high altitude in man.

Measurements have been made of hormonal changes relevant to salt and water balance during prolonged exposure to hypoxia to improve our understanding of the syndrome of acute mountain sickness. We have attempted to delineate the detailed inter-relationships between the renin-aldosterone and the vasopressin systems by a metabolically controlled study, involving an orthostatic stress (45 degrees head-up tilt) and an injection of a standard dose of ACTH to test adrenal responsiveness. Three Caucasian medical students underwent a 7-day equilibration at 150 m (Lima, Peru), followed by a 6-day sojourn at 4350 m (Cerro de Pasco, Peru) and a final 7 days at 150 m. Measurements were made of sodium and potassium balance, body weight and the 24-h renal excretion of vasopressin, cortisol and aldosterone 18-glucuronide. These variables showed little change, except for that of aldosterone 18-glucuronide, which fell sharply at altitude and rebounded even more sharply on return to sea level. At altitude, basal plasma levels of renin activity and aldosterone fell, and the response to orthostasis was attenuated, but the fall of plasma renin activity, as compared to plasma aldosterone, was delayed; on return to sea level this dissociation was exacerbated with the return of normal renin responsiveness lagging behind that of aldosterone. We suggest that unknown factors which dissociate the orthodox renin-aldosterone relationship, other than the activity of the angiotensin I-converting enzyme, are operative on exposure to hypoxia.

Adult↗
PubMed1982

Immune complex-like activity associated with abnormal serum lipoproteins in systemic erythematosus.

Sera from four patients with systemic lupus erythematosus (SLE) were shown to contain abnormal lipoproteins which behaved as immune complexes (IC). One IC lipoprotein (IC VLDL) had the density in ultracentrifugation of very low density lipoprotein, but a markedly altered electrophoretic mobility. A second IC lipoprotein (IC LDL) had the electrophoretic mobility of very low density lipoprotein but was slightly denser than low density lipoprotein on ultracentrifugation. Both the IC VLDL and IC LDL contained IgG and behaved as IC in the Clq deviation test, platelet aggregation and rheumatoid factor inhibition assays, but not in the conglutinin and Clq binding assays and the Clq solid phase assay. These differences could be due to the low densities of the IC VLDL and IC LDL. The abnormal lipoprotein IC disappeared with clinical remission in two patients and were not present in the sera of other patients with inactive or mild SLE, Type IV hyperlipidaemia, or during prednisone therapy or plasma exchange for other conditions. These IC appeared to be markers of severe and active SLE.

Adolescent↗