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Biomedical subjects

C W Smith

Publications and source records attributed to C W Smith.

At least 343 records · Page 19Linked to original sources
PubMed1983

Synthesis of [1, 6-cyclo (acetyl-1-L-glutamic acid, 2-D-phenylalanine, 3-D-tryptophan, 6-D-lysine)] luteinizing hormone-releasing hormone on poly-N-acrylylpyrrolidine resin.

The protected peptide, Ac-Glu(OBut)-D-Phe-D-Trp-Ser(But)-Tyr(But)-D-Lys (Z)-Leu-Arg(Tos)-Pro-Gly-NH2 was synthesized in a stepwise manner on a resin of poly-N-acrylylpyrrolidine using both acid cleavable N alpha-tert.-butyloxycarbonyl and base cleavable N alpha-fluorenylmethyloxycarbonyl protecting groups. After cleavage by ammonolysis in methanol, the tert.-butyl and benzyloxy-carbonyl side-chain protecting groups were cleaved with CF3-CO2H-thioanisole and the 1-6 amide ring formed by cyclization with diphenylphosphorylazide, after which the remaining tosyl protecting group was cleaved in HF-anisole. [1,6-Cyclo(Ac-Glu1, D-Phe2, D-Trp3, D-Lys6]LH-RH exhibited less than 10% of the antiovulatory potency of [D less than Glu1, D-Phe2, D-Trp3,6] LH-RH, a potent linear antagonist.

Acrylic Resins↗
PubMed1983

Rifampin affects polymorphonuclear leukocyte interactions with bacterial and synthetic chemotaxins but not interactions with serum-derived chemotaxins.

Three independent experimental approaches support the hypothesis that rifampin competes for receptors on polymorphonuclear leukocytes (PMLs) with small peptide chemoattractants, e.g., N-formylmethionylleucylphenylalanine (FMLP), but not with serum-derived chemoattractants (C5a). First, rifampin inhibited chemotaxis induced with FMLP but reversed the immobilization of PMLs that occurred at high FMLP concentrations. Second, rifampin competed with radiolabeled FMLP for binding sites on PMLs and displaced already-bound radiolabeled FMLP. Third, rifampin blocked and reversed the bipolar shape changes induced in PMLs by FMLP. These effects occurred at concentrations attained during rifampin therapy and were not due to rifampin toxicity. In contrast, no effect of rifampin was observed on serum-derived chemoattractants (C5a) in any of the three systems. The evidence suggests, therefore, that rifampin is a ligand for FMLP-type receptors on PMLs.

Binding, Competitive↗
PubMed1983

Digital subtraction angiography: limitations for the detection of pulmonary embolism.

Perfusion lung scanning, magnification pulmonary arteriography, and digital subtraction angiography (DSA) were performed prior to and following Gelfoam embolization of selected pulmonary arteries in eight canines. The sites of embolization were identified in 75% of perfusion lung scans, in 93% of magnification pulmonary arteriograms, in 75% of arterial phase DSA studies, and 100% of parenchymal phase DSA examinations. With technological advances, DSA has the potential to become the examination of choice for the evaluation of patients suspected of having pulmonary emboli.

Angiography↗
PubMed1983

Renal transplant arterial stenosis: percutaneous transluminal angioplasty.

Seven hypertensive patients underwent percutaneous transluminal angioplasty for relief of arterial stenosis complicating renal allotransplantation. Five had end-to-side anastomosis of the donor renal artery to the recipient external iliac artery, and two had end-to-end anastomosis of the donor renal artery to the recipient internal iliac artery. Each patient had developed hypertension (blood pressure greater than 145/95 mm Hg), elevated peripheral venous plasma renin, and six demonstrated decrease in renal function as detected by an increase in serum creatinine at least 2 months after transplantation and without evidence of rejection. Angioplasty was technically successful without significant complications and blood pressure and biochemical abnormalities were improved or stabilized in all seven patients.

Adolescent↗
PubMed1983

Comparison of cefamandole and cefazolin during cardiopulmonary bypass.

In a randomized comparison, concentrations of cefazolin were found to exceed those of cefamandole in serum, atrial appendage, and sternal bone in patients undergoing cardiopulmonary bypass. No postoperative infections and no antibiotic-related complications occurred in either patient group.

Aged↗
PubMed1983

Impaired polymorphonuclear leukocyte motility in malnourished infants: relationship to functional abnormalities of cell adherence.

The humoral and cellular contributions to PMN motility in vitro were studied in 37 malnourished (PCM) pediatric patients. Early-phase directed migration to BCF and to ZANS was diminished significantly (p less than 0.001) in severe PCM patients as compared to healthy adult or age-matched controls or respective nutritionally restored patients. Abnormalities were reversible after nutritional restoration and unrelated to occurrence of clinical infection. To determine the pathogenic mechanism of impaired PMN mobility in PCM, studies of cell morphology and adhesive function were performed. Abnormalities observed in severe PCM suspensions included significantly (p less than 0.001) increased baseline (unstimulated) adherence values and impaired CF modulation of adhesive function. Diminished enhancement of PMN adherence or decreased (relative to baseline) adherence values were observed in response to BCF (mean % delta = +5) or f-Met-Leu-Phe (mean % delta = -6) as compared to adult PMN values of +28% delta and +31% delta, respectively. That these abnormalities may result from in vivo CF prestimulation was suggested by findings of "activated" PMN morphology in suspensions prior to in vitro stimulation, and abnormalities of the distribution of PMN surface adhesion sites under conditions of chemotactic stimulation. Further investigations will be required to determine the underlying pathogenic mechanism(s) accounting for our observations.

Cell Adhesion↗
PubMed1982

Retrograde cardiovascular angiography in infants, using a 3.6 French catheter.

Diagnostic retrograde arterial catheterization in infants, and small children has been constrained by the risk of arterial thrombosis and the low flow rate of catheters less than #5 French. We performed retrograde arterial catheterization (percutaneous technique in 21 of 24 patients) on 24 infants and small children (median age 3 months, median weight 4.1 kg), using a 3.6 French performed polyethylene catheter. Systemic heparinization was used. Among the group, we performed 23 aortograms, and 4 selective injections into a bronchial artery; all angiograms were of diagnostic quality. Injection rates ranged from 3 cc/sec to 10 cc/sec (median 5 cc/sec) with a peak developed pressure of 300 PSI to 900 PSI (median 700 PSI). No catheter-related complications were encountered during the study. Four of 24 patients developed a decreased pulse, noted immediately following the catheterization; however, pulses returned to normal within 24 hours, and late blood pressure assessment revealed no abnormalities in the catheterized leg. We now recommend this catheter for infants less than 10 kg when the following angiograms are required: 1. retrograde aortography (truncus arteriosus, pulmonary atresia, aortic stenosis, coarctation, coronary anomalies) 2. selective injections of bronchial arteries 3. retrograde catheterization of surgical shunts.

Angiography↗
PubMed1982

Cytoplasmic microtubules in polymorphonuclear leukocytes: effects of chemotactic stimulation and colchicine.

Indirect immunofluorescent (IIF) techniques employing antitutulin and anticentrosome antibodies were modified for studies of migrating polymorphonuclear (PMNs) leukocytes exposed to gradients or uniform concentrations of chemotactic factor (CF). No significant changes in microtubule (MT) number per cell occurred with chemotactic activation. Significant increases in average MT length per cell occurred upon exposure to gradients or uniform concentrations of CFs. Elongation of MT parallel to the direction of cell migration occurred coincident with shortening of other sets of MTs perpendicular to the direction of cell migration. MT extended radially from a single microtubule organizing center (MTOC) in greater than 99.9% of cells. Following chemotactic activation, the location of the MTOC was observed between nuclear lobes in 65% of fully polarized cells, "posterior" to the nucleus in congruent to 34% and "anterior" in less than 1%. Thus alterations of MT array occur coincident with cell orientation or migration in response to chemotactic stimuli.

Adult↗
PubMed1982

On the self-serving function of an academic wooden leg: test anxiety as a self-handicapping strategy.

The present study investigated the hypothesis that psychological symptoms may serve a self-protective function by providing an alternative explanation for potential failure in evaluating situations. It was hypothesized that highly test-anxious subjects would report anxiety symptoms in a pattern that reflected strategic presentation of symptoms; more specifically, it was predicted that greater reported anxiety should result when anxiety was a viable explanation for poor performance on an intelligence test and that lower reported anxiety should result when anxiety was not a viable explanation for poor performance. Analysis of state measures of self-reported anxiety supported these predictions. Further analysis indicated that when anxiety was not a viable explanation for poor test performance, high test-anxiety subjects reported reduced effort as an alternative self-protective strategy. These results are discussed in terms of traditional models of symptoms as self-protective strategies, current social psychological models of symptoms, and in reference to recent theory and research about the nature and treatment of test anxiety.

Achievement↗
PubMed1982

Simultaneous bi-plane digital video-fluoroscopy.

A prototype system for digital subtraction angiography that is capable of acquiring digitized video-fluoroscopic images simultaneously from both anterior and lateral imaging chains of a conventional bi-plane system was developed. A hardware module that takes images from both the anterior and lateral video cameras and displays them both on a single video image prior to digitization was designed and constructed. The three-dimensional information provided by a digital bi-plane images should improve the accuracy of cardiac-ventricular function studies. In addition, bi-plane imaging should reduce the need for additional views and the associated repeated injections of contrast media. With this technique, digital bi-plane imaging can be carried out with commercially available systems without duplication of the digital-processing chain.

Animals↗
PubMed1982

Evaluation of digital venous angiography for the diagnosis of renovascular hypertension.

Thirty-two patients being evaluated for hypertension by angiography were also studied by digital video subtraction angiography (DVSA). Twenty-three of the 76 renal arteries were found by conventional angiography to have significant lesions. Two experienced angiographers evaluated the DVSA studies without knowledge of the angiographic results. The accuracy of DVSA for evaluation of renal arteries was 87% for Observer I and 80% for Observer II. Sensitivities were 87% and 83% and specificities 87% and 79% for the two observers. Of the 13 patients with significant lesions, Observer I identified at lest one lesion in all 13 while Observer II identified a lesion in 12 of the 13. The high false-positive rate (26% for Observer I and 37% for Observer II) was thought to be caused by subtraction artifacts, quantum noise, relatively low spatial resolution, and the Mach effect.

Angiography↗
PubMed1982

A microcomputer system for prescription, calculation, verification and recording of radiotherapy treatments.

The design of a microcomputer system for the reduction of mistakes in radiotherapy is described. The system covers prescription entry, prescription and treatment calculations, and verification and recording of the treatment set-up. A telecobalt unit was interfaced to the system and in the first 12 months 400 patients have been prescribed and 5000 treatment fields verified. The prescription is entered by the medical officer using an interactive program and this prescription provides the reference for verifying the treatment set-up. The program allows amendments to the prescription to be made easily during the treatment course. The treatment parameters verified are field size, wedge and treatment time. The system uses bar-codes for patient and field identification. A reduction in the number of mistakes has been achieved and future developments are discussed.

Computers↗
PubMed1982

Ciguatera fish poisoning epidemiology of the disease on St. Thomas, U.S. Virgin Islands.

In a random household survey conducted on St. Thomas, U.S. Virgin Islands, the incidence of ciguatera fish poisoning was found to be 36.5 cases per 1,000 population per 5 years (95% confidence limits +/- 16.9 cases per 1,000 population per 5 years). An average of 3.6 cases per 1,000 population per year were diagnosed in the hospital emergency room on St. Thomas. Cases seen in the emergency room occurred most frequently among persons aged 30-39 years. No clear seasonality for cases could be demonstrated. In an investigation of cases occurring between 1 January and 10 April 1980, illness was caused by a variety of different fish, with carrang (Caranx ruber) the species most commonly implicated. Patients and age-matched controls ate fish with equal frequency; patients were significantly more likely to have had previous episodes of ciguatera fish poisoning than were controls.

Adolescent↗