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Biomedical subjects

D C Smith

Publications and source records attributed to D C Smith.

At least 235 records · Page 13Linked to original sources
PubMed1988

Early postoperative hypoxia during transport.

The incidence of immediate postoperative hypoxaemia following general anaesthesia was studied using a pulse oximeter in 120 ASA category I and II patients during transport to the recovery room. Thirty-two percent of those not given oxygen during transport developed desaturation (SaO2 less than 90%) in spite of receiving 100% oxygen for 5 min before transport. In 14.3% of patients SaO2 decreased to less than 85%. None of the patients given oxygen 2 litre min-1 via a nasopharyngeal catheter during transport exhibited an SaO2 less than 90%. The only variable which correlated with the development of desaturation was the duration of anaesthesia.

Adult↗
PubMed1988

A technique for estimating the probability of clots in blood/contrast agent mixtures.

Blood that contaminates the contrast agent syringe during angiography may clot and is thus a potential source of emboli. The older, high-osmolality agents prevent clotting. Newer, low-osmolality agents, while possessing other advantages, are less effective in this regard. The time over which such mixtures do not contain clot can be determined by allowing gross clotting to take place, modeling the process mathematically and determining the clot-free time from the model. Blood-contaminated Omnipaque-300 (Winthrop-Breon, New York, NY) (iohexol), Isovue-300 (E.R. Squibb and Sons, New Brunswick, NJ) (iopamidol), Hexabrix (Mallinckrodt, St. Louis, MO) (ioxaglate sodium meglumine), Renografin-76 (E.R. Squibb and Sons, New Brunswick, NJ) (diatrizoate sodium meglumine), and saline were studied in glass and plastic syringes (80 samples of each agent). After deliberate blood contamination, Renografin and Hexabrix showed no clots during the 90-minute study period. There was, however, a 1.3% chance of clotting in Omnipaque (range 0.4%-4.0%) and a 1.9% chance of clotting in Isovue (range 0.6%-5.5%) at 5 minutes after contamination of these contrast agents in plastic syringes. The chance of clotting in glass containers was significantly greater. We conclude that Hexabrix is a substantially stronger anticoagulant than Omnipaque and Isovue. Furthermore, it appears that this method will allow determination of clotting risks for other combinations of contrast agent and container.

Angiography↗
PubMed1988

Anger, perceived control and school behavior among students with learning problems.

With regard to students with learning problems, findings indicate that the more severe the learning problem, the greater the tendency toward anger in response to conflicts at school. The relationship between learning problem severity and perceptions of control at school was not significant, but anger was negatively correlated to perceived control. None of the variables were significantly related to misbehavior. A stepwise regression analysis indicated perceived control as the most potent single variable accounting for the variance in anger scores. Overall, findings highlight implications for work focused on reactions to learning problems and factors associated with their cause and correction.

Adolescent↗
PubMed1988

Hinged shutter for image alternator.

A hinged, mobile shutter was designed to reduce the effect of extraneous light on the interpretion of chest radiographs and angiograms. The authors believe that the device greatly facilitates the daily work by decreasing eye fatigue and probably by increasing the signal-to-noise ratio.

Radiography↗
PubMed1988

Systemic-to-pulmonary collateral vessels and shunts: treatment with embolization.

Abnormal collateral vessels develop frequently in patients with right ventricular outflow or pulmonary artery obstruction. Surgery is usually used to obliterate these vessels but may be difficult, involve prolonged operative time, or require a different thoracotomy than that used for correction or palliation of the cardiac anomaly. Sixteen trans-catheter embolization procedures were performed in 15 patients with systemic-to-pulmonary collateral vessels and shunts. In eight embolization procedures performed because of congestive heart failure or low oxygenation, clinical improvement was obtained in seven. In all six patients who underwent embolization preoperatively, the outcome of surgical correction or palliation was satisfactory. Hemorrhage ceased in the two patients with hemoptysis. There were two complications, one transient loss of femoral pulse and one segmental pulmonary infarction. Embolization is a useful adjunct to surgery and medical management of patients with systemic-to-pulmonary collateral vessels and shunts.

Adolescent↗
PubMed1988

Adhesion of composite resin to bleached and unbleached bovine enamel.

Cylinders of microfil and small-particle light-cured composite resin were bonded to the flattened labial enamel surface of young bovine incisor teeth which had previously been subjected to four different treatments: (1) teeth immersed in 35% hydrogen peroxide (HP) for 60 min and etched (E) with 37% phosphoric acid gel for 60 sec; (2) teeth immersed in saline (S) for 60 min and E for 60 sec; (3) teeth E for 60 sec and immersed in HP for 60 min; and (4) teeth E for 60 sec, immersed in S for 60 min. Specimens were stored in water at 37 degrees for one and seven days prior to tension- and shear-testing. A total of 256 teeth was tested--eight teeth in each group for each day, for each resin, and for each test. Statistical analysis of the results indicated that there was a highly significant reduction in adhesive bond strength of the resins when the enamel was exposed to HP as compared with S. SEM examination of randomly selected fractured test specimens indicated that this reduction in adhesive bond strength occurred primarily at the bonding resin-enamel interface. Less significant differences in bond strength were noted in the control specimens, with regard to resin type, time of storage, and the etching order.

Adhesiveness↗
PubMed1988

Dental cements.

Explore the source record for details and available documents.

Dental Cements↗
PubMed1988

Percutaneous transluminal renal angioplasty in the patient with a solitary functioning kidney.

Since the introduction of percutaneous transluminal renal angioplasty, it has become established as an effective treatment for the correction of renovascular hypertension or the preservation of renal function. However, there has been a general reluctance to use it or other interventional procedures in any patient with a solitary functioning kidney. We attempted renal angioplasty in 11 patients each of whom had a solitary functioning kidney. All 11 had had either a previous contralateral nephrectomy or an autonephrectomy from chronic arterial occlusion. The patients ranged in age from 42 to 81 years. In nine of the 11 patients, a catheter was negotiated across the stenosis, and the lesion was dilated successfully. In two, the lesion could not be crossed. In the group of nine patients whose lesions were dilated successfully, clinical follow-up (2-180 weeks) revealed that hypertension was cured in four and improved in five. Of the two patients in whom angioplasty was not possible, one required emergency renal bypass surgery and the other had no change in renal status. Renal function test results after the procedure were variable and did not correlate with decreases in blood pressure. We conclude that percutaneous renal angioplasty is a satisfactory alternative to surgery for the treatment of renovascular hypertension or the preservation of renal function in a patient with a solitary functioning kidney.

Adult↗
PubMed1988

Future directions for research on materials and design of dental implants.

Previous reviews underscore the uncertainties in our knowledge of the influence of material characteristics, design-shape, and surface texture on the implant material-tissue interface. Current implant designs are based on intuitive approaches and there are no general principles for prediction of success of implant systems. Data on implant surfaces prepared by customary preparative techniques show that they are highly variable and dependent on processing. The long-term (years) effects of trace element release from implants is little understood because of past errors in analytical techniques and paucity of relevant data. To place the development of future implant systems on a more rational basis, scientific studies are needed (1) to identify and characterize new and modified materials and surfaces, (2) to validate surface characterization procedures and evaluate tissue responses to standardized surfaces, and (3) to measure trace and subtrace element levels in animal and human tissues over time in order to establish normal and pathologic limits.

Animals↗
PubMed1987

Psychosocial effects of radiotherapy after mastectomy.

Psychosocial morbidity was measured in 47 patients who received postoperative radiotherapy and in 38 who received no further treatment after mastectomy. Roughly one third of all patients experienced depression or anxiety. One month after operation, before radiotherapy, there were no significant differences between the two groups in any of the measures of psychosocial morbidity. Knowledge of impending treatment did not seem to influence morbidity. At three months patients who had completed radiotherapy had significantly more somatic symptoms and social dysfunction than those not so treated. At six months the radiotherapy group continued to show more somatic symptoms, but a year after operation there were no significant differences between the groups. Although several patients who received radiotherapy were upset by their treatment, the study failed to confirm that depression and anxiety were commoner among those given radiotherapy than among patients given no further treatment.

Anxiety↗
PubMed1987

Early effects of HIV on CD4 lymphocytes in vivo.

Low circulating CD4 cell numbers and CD4 cell dysfunction are distinguishing features of HIV-mediated disease. The current study delineates the in vivo effects of HIV on distinct functional subsets of CD4 cells in homosexually active men who have been infected with HIV for different lengths of time, and examines the capacity of lymphocytes from these men to proliferate in vitro in response to soluble antigen. Although peripherial blood mononuclear cells from most acquired immune deficiency syndrome (AIDS) patients did not proliferate in response to either tetanus toxoid or Candida albicans, cells from most HIV seropositive men without AIDS, many of whom had been infected for more than 18 mo, responded normally to both. Non-responsiveness in HIV-infected men without AIDS was a late event and was associated with longer duration of infection, lower CD4 cell numbers, and subsequent development of AIDS. A defect in this response was observed in only one of 19 HIV seropositive men whose CD4 levels were greater than 300/mm3, but in eight of 10 with levels less than 300/mm3. The defect could not be attributed to a selective depletion of defined CD4 subpopulations that respond to soluble antigen. Dual-color immunofluorescent flow cytometry indicated that 4B4+, 2H4-, and HB-11- CD4 cells were not lost at a faster rate than other CD4 subsets.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The determination of Al, Cr, Co, Fe, and Ni in whole blood by electrothermal atomic absorption spectrophotometry.

Procedures for the determination of aluminum, chromium, cobalt, nickel, and iron in whole blood are presented and discussed. Chromium, cobalt, nickel, and iron were determined from one sample after decomposition of the blood with a mixture of nitric and perchloric acids. A graphite furnace was used for the determination of chromium, cobalt and nickel, and flame AAS was used for iron. The determination of Al was done from separate samples by GFAAS after dilution with 1% Triton TX-100. The normal concentration of these elements was measured in rabbit and dog blood.

Aluminum↗