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Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 1,099 records · Page 61Linked to original sources
PubMedDate not supplied

Platelet use in pediatric oncology: a review of 393 transfusions.

A total of 393 platelet transfusions, administered on the pediatric service at the M. D. Anderson Hospital and Tumor Institute between March, 1973, to December, 1974, were reviewed. Of these 64 were administered on indications of hemorrhage or surgery, while 324 were administered prophylactically. In only 33% was an adequate platelet rise seen, and in only 40% of those bleeding was the bleeding controlled. The primary factor precluding the success was the number of previously administered platelet transfusions. Infection, the use of random or single donors, and ABO matching had no effect on the outcome, but this was not accentuated in the bleeding patients. Surprisingly, transfusions in patients with leukemia resulted in greater success than transfusions in patients with solid tumors. The lower the platelet count prior to transfusion, the less likely the transfusion was to be successful.

Blood Cell Count↗
PubMedDate not supplied

Temporal patterns of exposure and nonmalignant pulmonary abnormality in Quebec chrysotile workers.

Questionnaire, radiographic, and lung function information for 983 Quebec chrysotile workers at work in 1966 was used to develop five clinical response scales (i.e., parenchymal and pleural fibrosis, airflow limitation, chronic bronchitis, and airway reactivity). The relationship of the scales to variables describing temporal patterns of exposure was studied, taking into account cumulative exposure, age, and smoking. All response scales related to variables containing only time information, and in all cases temporal patterns of exposure influenced exposure response relationships. For pulmonary fibrosis, the strongest relationships were to cumulative exposure; for pleural fibrosis to exposure peaks and residence time of dust in the lung; for airway reactivity to early and recent exposure; and for airflow limitation and chronic bronchitis to smoking and to dust level and load over time. These results add to the gathering evidence that exposures to environments containing airborne asbestos may result in airway abnormalities.

Adult↗
PubMedDate not supplied

"Camping up" self-esteem in children with hemophilia.

Children with hemophilia have often been viewed at greater risk for altered self-esteem than their healthy counterparts. Our article shares the positive effects of the camp experience on children with hemophilia and subsequent enhancement of self-esteem. Interaction and support in the camp environment provide an opportunity for these children to gain independence and "prove" their self-worth and ability. Previous literature has provided a variety of findings on the relationship between chronic illness, such as hemophilia, and self-esteem alterations. We identify many opportunities for future education and research to provide quality nursing support to this unique population.

Attitude to Health↗
PubMedDate not supplied

Seasonal and interindividual variation in field water metabolism of female meadow voles Microtus pennsylvanicus.

We analyzed variations in water flux rates on a large sample of meadow voles (Microtus pennsylvanicus) to quantify the effect of season on water metabolism of individuals and to examine patterns of intra- and interindividual variability. Voles were nonreproductive females maintained in outdoor enclosures where they fed on natural vegetation. They were injected one to three times with doubly labeled water, which resulted in one to six measures of daily water flux rate per individual. Summer water flux rates of voles were 258% of the predicted values for herbivorous eutherian mammals of similar size. To date, very few studies have focused on mammals with such high water flux rates. Body water volume of individuals was higher in summer than in winter (75.6% vs. 72.5%), and water flux rate of animals was 12.5% higher in the winter season (0.99 vs. 0.88 mL H2O g-1 d-1). Between-season differences in water fluxes were proportional to differences in energy expenditures, hence the water economy index remained constant across seasons (0.30 mL H2O kJ-1). Intraindividual variability of water flux rate was high compared to interindividual variability (repeatability, r<0.30), which will make it difficult to study natural selection of water metabolism in a microevolutionary framework, at least in meadow voles.

Animals↗
PubMedDate not supplied

Initial in vivo tests of an electrohydraulic actuated total artificial heart.

The authors are involved in developing a total artificial heart (TAH) for permanent human use. This device was designed to fit human anatomy, and it has housings made of carbon fiber-epoxy composite and titanium. Tissue valves and protein coating of blood contacting surfaces minimize the need for anticoagulants. A continuously reciprocating electrohydraulic actuator is packaged between two alternately ejecting and passively filling ventricles. The control system varies the pump rate to maintain average left ventricular filling at 90%. This TAH in vivo successively progressed through 1, 5, 9, and 45 day implants in calves of 84, 94, 82, and 82 kg preoperative body weights. The operating modes include automatic and fixed rate. The chronic and acute effects of varying the right pump displaced stroke volume indicated the need for it to be limited to 85% of that of the left for stable hemodynamics at maximum flow. The pump exhibited afterload insensitive and preload sensitive performance. Pump output ranged from 4.0-9.5 L/min at left atrial pressures of 7-16 mmHg at pump rates of 80-160 beats/min in these four experiments. These data suggest that this device will meet clinical hemodynamic requirements; it has the potential for total implantable cardiac replacement.

Animals↗
PubMedDate not supplied

Induction of ventricular collapse by an axial flow blood pump.

An important consideration for clinical application of rotary blood pump based ventricular assist is the avoidance of ventricular collapse due to excessive operating speed. Because healthy animals do not typically demonstrate this phenomenon, it is difficult to evaluate control algorithms for avoiding suction in vivo. An acute hemodynamic study was thus conducted to determine the conditions under which suction could be induced. A 70 kg calf was implanted with an axial flow assist device (Nimbus/UoP IVAS; Nimbus Inc., Rancho Cordova, CA) cannulated from the left ventricular apex to ascending aorta. On initiation of pump operation, several vasoactive interventions were performed to alter preload, afterload, and contractility of the left ventricle. Initially, dobutamine increased contractility and heart rate ([HR] = 139; baseline = 70), but ventricular collapse was not achievable, even at the maximal pump speed of 15,000 rpm. Norepinephrine decreased HR (HR = 60), increased contractility, and increased systemic vascular resistance ([SVR] = 24; baseline = 15), resulting in ventricular collapse at a pump speed of 14,000 rpm. Isoproterenol (beta agonist) increased HR (HR = 103) and decreased SVR (SVR = 12), but ventricular collapse was not achieved. Inferior vena cava occlusion reduced preload, and ventricular collapse was achieved at speeds as low as 11,000 rpm. Esmolol (beta1 antagonist) decreased HR (HR = 55) and contractility, and ventricular collapse was achieved at 11,500 rpm. Episodes of ventricular collapse were characterized initially by the pump output exceeding the venous return and the aortic valve remaining closed throughout the cardiac cycle. If continued, the mitral valve would remain open throughout the cardiac cycle. Using these unique states of the mitral and aortic valves, the onset of ventricular collapse could reliably be identified. It is hoped that the ability to detect the onset of ventricular collapse, rather than the event itself, will assist in the development and the evaluation of control algorithms for rotary ventricular assist devices.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

Inhibition of allergic reactions with antibodies to IgE.

Numerous clinical studies show that direct interference with the IgE response leads to a decrease or elimination of allergic symptoms. The aim of these studies was to design a therapy aimed at decreasing IgE levels in order to ameliorate atopic disease. To this end, a murine monoclonal antibody, MAE11, directed against IgE was identified, which had all the properties necessary to interfere with IgE responses, but lacked the harmful side effects of inducing receptor cross-linking. The antibody was selected on the basis of its ability to bind circulating IgE at the same site as the high-affinity receptor, thus blocking the binding of IgE to mast cells and basophils. To allow for possible chronic administration and to avoid the problems of antigenicity, MAE11 was humanized. The best of several humanized variants, version 25 (rhumAb-E25) was selected since it possessed binding affinity and biological activity comparable to MAE11. Clinical studies are underway to determine the safety and efficacy of this treatment for allergic rhinitis and asthma.

Allergens↗
PubMedDate not supplied

Comparison of oculoplethysmography/carotid phonoangiography with duplex scan/spectral analysis in the detection of carotid artery stenosis.

The accuracy of the duplex scan with spectral analysis (DS/SA) in predicting the presence of arteriographic carotid stenosis was compared to that of oculoplethysmography/carotid phonoangiography (OPG/CPA) in 234 vessels from 117 patients who had had both non-invasive studies in addition to independently interpreted arteriograms. The DS/SA with 212/234 (91%) overall correct responses was superior to the OPG/CPA which properly classified 181/234 (77%) of the vessels (p less than .01). Of major clinical impact was the superiority of the DS/SA (p less than .001) in identifying the 72 vessels with 50-99% stenosis. The OPG/CPA had a discouraging 39/72 (54%) false-negative rate in this group whereas the DS/SA missed only 9/72 (12%) of these arteries. Of those 39 incorrect responses for the OPG/CPA, 26/39 (67%) were in patients with a 50% or greater stenosis on the contralateral side. This is a recognized area of weakness for that test. Based on the results of this study, we have abandoned the use of the OPG/CPA in the evaluation of patients with suspected carotid stenosis and rely solely on the duplex scan with spectral analysis.

Carotid Artery Diseases↗
PubMedDate not supplied

Common migraine and vestibular function. Electronystagmographic study and pathogenesis.

Even though "classic migraine" and "complicated migraine" may be diagnosed readily, "common migraine" may be easily confused with other types of vascular headaches. This differential diagnosis is of great importance for the appropriate choice of drug therapy. It is frequently stated that family history of migraine and history of motion sickness in childhood suggest that a periodic vascular headache is most likely of migrainous origin; although this statement applies to ophthalmoplegic and hemiplegic migraine, it is doubtful that it applies to common migraine. In fact, in a pilot study of patients with common migraine, we have observed that family history and history of motion sickness in childhood did not contribute to the diagnosis. Vestibular dysfunctions are frequently associated with migraine including the common type. Utilizing labyrinthine tests with the aid of electronystagmography, abnormalities of labyrinth function were demonstrated in 80% of patients with common migraine who had no history of vertigo or of other otological and neurological disorders.

Adult↗
PubMedDate not supplied

Rapid diagnosis of catheter-related sepsis using the acridine orange leukocyte cytospin test and an endoluminal brush.

BACKGROUND: In neonates, the acridine orange leukocyte cytospin (AOLC) test has been found to be a highly sensitive test for the detection of infected i.v. catheters in situ, which provides a result in less than 1 hour. Preliminary data suggested that the AOLC test was of limited value in adults. We report here a modification of the test for adult patients with indwelling central venous catheters. METHODS: A prospective study was performed on two groups of 50 adult patients with suspected sepsis and a central venous catheter. The AOLC test was carried out after the clinical decision to remove the catheter had been made. In group 1 patients, a blood sample was withdrawn from the catheter for the AOLC test. In the patients in group 2, an endoluminal brush was used to "sweep" the catheter before the collection of the blood sample. Results of the AOLC test were compared with culture of the removed catheter tip. RESULTS: From the catheters in group 1 (no brush), 17 catheter tips were found to be infected, but the AOLC was positive in only two patients (12%). In group 2 (brush), 18 tips were infected, and the AOLC test was positive in 15 patients (83%). The use of the endoluminal brush significantly improved the yield of the AOLC test (p < .01) to levels reported in neonates. The AOLC test produced no false positives in either group CONCLUSION: When used independently, the AOLC test was not sensitive enough to detect catheter-related sepsis. However, in combination with an endoluminal brush, the AOLC test was much more sensitive and has the potential to provide a simple, rapid, and accurate diagnostic test for catheter-related sepsis, which does not require removal of the catheter.

Acridine Orange↗
PubMedDate not supplied

Catalytic mechanism of an abzyme displaying a beta-lactamase-like activity.

A catalytic IgG (Ab2) displaying a beta-lactamase-like activity was previously obtained by using the antiidiotypic pathway: the particularity of this antibody is that it is a true antiidiotype of the beta-lactamase active site. We have previously demonstrated that this IgG has retained some of the structural information displayed by the beta-lactamase active site, evident from data that polyclonal anti-Ab2 antibodies (Ab3) recognize beta-lactamase. In this article, we investigated the catalytic mechanism of the abzyme compared to that of the enzyme. The experimental data allow us to hypothesize the catalytic residues required for catalysis.

Animals↗
PubMedDate not supplied

Trends in the management of fractured mandibles 1983-93.

The aetiology, presentation and management of fractured mandibles were investigated in a major accident and emergency department in 1983 and 1993. Demographic features of patients in both years were similar: most injuries were in males (89%), most were a result of an assault ( > 75%), and 50% of the patients presented for treatment between the hours of 10pm and 5am. There were striking reductions in the numbers of patients who waited more than 24-hours for an operation (60% in 1983; 34% in 1993), and out-of-hours operating (60% in 1983; 41% in 1993). There was an increase in the number of patients for whom consultants were the principal operator (13% in 1983; 32% in 1993). Changes in the methods of treatment included a decrease in the use of postoperative intermaxillary fixation (98% in 1983; 56% in 1993) and an increase in internal fixation using bone plates (2% in 1983; 53% in 1993). Total inpatient stay was the same in both study years (mean = 3 days), and there was no difference in duration of stay between treatment modalities (internal versus intermaxillary fixation).

Accidents, Traffic↗
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The health insurance jigsaw. How to line up an arrangement that will keep you covered.

Health insurance options for people who are HIV-positive, while limited, have improved. Experts suggest strategies for HIV-positive people looking for coverage, including using unions, fraternal organizations, high-risk pools, VA insurance, "green card" marriages, and large employer groups and group plans offered by professional associations. Advice is also given for keeping health insurance, particularly for people changing jobs, going on disability, or for those who cannot afford to keep up with the benefits.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Sodium butyrate induces growth inhibition and modulates galectin-8 expression in human lung carcinoma cells.

Galectins are animal lectins, which may play a role in neoplastic transformation. Po66-Carbohydrate Binding Protein (Po66-CBP) belongs to the galectin-8 family and is expressed in lung tumor cells but not in normal ones. Recent studies showed that galectin-8 could be used for human lung squamous cell carcinoma radioimmunotherapy. To optimize this method of treatment, we attempted to increase galectin-8 expression in human lung tumor cells. A human lung squamous (SK-MES-1) or adeno (A 549) carcinoma cell line was grown with or without sodium butyrate. Cell growth, morphology, transcriptional, expression translational expression and cellular localization of galectin-8 were studied. 3 mM of sodium butyrate inhibited the two cell lines' growth after 48 hours of treatment, but only in SK-MES-1 cells galectin-8 expression is modulated without any secretion and cellular localization modifications, apoptosis or necrosis. Sodium butyrate could be an interesting tool in optimizing the radioimmunotherapy of human lung squamous carcinoma, but not of adenocarcinoma.

Adenocarcinoma↗