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Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and characterization of two opioid peptides from a bovine hemoglobin peptic hydrolysate.

Two opioid peptides were isolated from a bovine hemoglobin hydrolysate, by use of gel permeation (GP) and reverse phase (RP) high performance liquid chromatography (HPLC). Their primary structure and accurate molecular weights, determined by amino acid analysis and fast atom bombardment (FAB) mass spectrometry, were identical to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin 7) of the beta-chain of bovine hemoglobin. The same fragments occur in human hemoglobin in positions 32-41 and 33-41 of the beta-chain, respectively. The opioid potency of these peptides, exhibited by use of electrically stimulated muscle of isolated guinea-pig ileum (GPI), were significant and comparable with some others previously described. In addition, the location of the two opioid peptides, VV-hemorphin-7 and LVV-hemorphin-7, revealed the existence of a "strategic zone" both in the bovine and human beta-chains of hemoglobin.

Amino Acid Sequence↗
PubMed1992

Divergent evolution of pyrimidine biosynthesis between anaerobic and aerobic yeasts.

A cDNA encoding the dihydroorotate dehydrogenase (DHOdehase; EC 1.3.3.1) of the yeast Schizosaccharomyces pombe was isolated by functional complementation in Saccharomyces cerevisiae. A divergent subcellular compartmentation of the DHOdehase of each yeast was shown. The DHOdehase from Sch. pombe was localized in the mitochondria whereas its homolog from S. cerevisiae was found to be cytosolic. The heterologous expression of the Sch. pombe enzyme in S. cerevisiae allowed us to demonstrate that the Sch. pombe DHOdehase activity requires the integrity of the mitochondrial electron transport chain. Indeed, the presence of a mutation inactivating cytochrome b abolished the complementation of a S. cerevisiae ura1 mutant by the corresponding Sch. pombe gene. By contrast, in vitro studies have revealed that the DHOdehase of S. cerevisiae uses fumarate as terminal electron acceptor. These results are discussed in relation to the anaerobic growth competence of the two yeasts and to the fermentative processes they use.

Aerobiosis↗
PubMed1992

Isolation and characterization of a bradykinin-potentiating peptide from a bovine peptic hemoglobin hydrolysate.

A bradykinin potentiating peptide was isolated from a peptic bovine hemoglobin hydrolysate, by the use of reversed-phase high-performance liquid chromatography (RP-HPLC). Its primary structure, determined by fast atom bombardment (FAB) and tandem mass spectrometry (MS/MS), was identical to fragment 129-134 of the alpha-chain of bovine hemoglobin. The bradykinin potency of this peptide, as exhibited by the guinea-pig ileum contraction, was significant and comparable with some others previously described.

Amino Acid Sequence↗
PubMed1992

The comparative concurrent validities of the Shipley Institute of Living Scale and the Henmon-Nelson Tests of Mental Ability.

This study compared the abilities of the Shipley Institute of Living Scale and the Henmon-Nelson Tests of Mental Ability to predict Wechsler Adult Intelligence Scale-Revised (WAIS-R) scores in psychiatric hospital patients. The Henmon-Nelson DIQs accounted for about 50% more WAIS-R Verbal and Full Scale IQ variance than did the Shipley IQs, apparently because of their higher correlations with the Information, Vocabulary, and, perhaps, Similarities subtests. Because Henmon-Nelson scores were more variable and generally higher than their WAIS-R counterparts, statistical adjustments were needed to optimize Wechsler IQ estimates. Therefore, regression formulae and a conversion table for the estimation of WAIS-R Full Scale IQs from Henmon-Nelson and Shipley intelligence scores also are presented.

Adult↗
PubMed1992

Do computer-administered Minnesota Multiphasic Personality Inventories underestimate booklet-based scores?

We ran meta-analyses that compared the Minnesota Multiphasic Personality Inventory scale scores produced in 770 booklet and 762 computer administrations described by nine studies. While most of the differences were small, the computer-based scores significantly underestimated their booklet counterparts on 8 of the 13 scales. The average underestimate was about three-quarters of a T-score point and accounted for around 4% of the reliable variance. These findings suggest that separate norms and profile sheets for computer-administered MMPIs might be helpful.

Adult↗
PubMed1992

Systemic embolism as a complication of percutaneous mitral valvuloplasty.

Systemic embolism is a potential and severe complication of percutaneous mitral valve dilatation. In our series of 80 cases, the incidence of systemic embolism was 3.75% (3 cases). Two cases occurred during the procedure itself. The cause of embolism was different in each case: cruoric thrombus formation occurred in 2 cases during or after dilatation, and was attributable to inappropriate heparinization, and catheter and guidewire thrombogenicity. In both cases heparin administration was delayed or given at a lower dosage. In the third case, calcific embolism occurred several days after valve dilatation. We think that the embolic calcified fragment was detached from the mitral leaflet at the time of or after balloon inflation. In these 3 cases, intraatrial thrombus mobilization was not the mechanism of systemic embolism. In 2 cases, transesophageal echocardiography had been performed before dilatation and excluded the presence of an atrial thrombus the day before the procedure. It is concluded that, together with mobilisation of left atrial thrombi, which can be adequately detected by transesophageal echocardiography, catheter-induced thrombi represent a significant cause of embolic complications and must be prevented by giving full-dose heparin during the total duration of the procedure. Calcific embolism may also occur, and may become more frequent if mitral valve balloon dilatation is proposed to a larger number of patients with valvular and subvalvular calcifications.

Aged↗
PubMed1992

Case report 709: Transverse fracture with epidural and small paravertebral hematomata, in a patient with ankylosing spondylitis.

This case demonstrates the potential pitfall of obtaining CT images in the axial plane alone, with a fracture parallel to the imaging plane mimicking vertebral body destruction and associated epidural mass mimicking neoplasm. Chan et al. have discussed the value of reformatted CT images in coronal and sagittal planes to define better transverse vertebral fractures. The case also demonstrates the potential danger of bypassing plain radiographs with the aim of facilitating a rapid diagnosis. Plain films, performed in this case only after CT myelography, clearly demonstrated a transverse pathological fracture in an ankylosed spine with no evidence of neoplastic destruction, enabling easy diagnosis of SEH on the CT appearance. The delayed onset of neurological deficit after fracture reinforces the importance of education of the patient with AS. This principally involves altering patients to the fragility of their spine and to the importance of avoiding spinal trauma. However, patients with known AS should be warned to seek medical advice after even minor spinal trauma with the aim of minimizing the incidence of delayed neurological complications such as occurred in this patient.

Aged↗
PubMed1992

Glycoproteins and lectins in cell adhesion and cell recognition processes.

The discovery of endogenous lectins having specific and high affinity for the carbohydrate portions of glycoproteins has opened up new directions in the field of cell adhesion and cell recognition. Two endogenous lectins, termed as CSL and R1, initially isolated from the rat cerebellum and having a wide distribution in mammalian tissues, have been shown to participate in essential mechanisms of cell adhesion. The membrane-bound lectin R1 seems to be involved in transient recognition between neuronal cells, followed by elimination of the glycoprotein ligands at the surface of the recognized cell. In contrast, CSL is a molecule involved in adhesion between various normal or transformed cells since it participates in the formation of tight junctions. The glycoprotein ligands recognized with higher affinity by these two lectins seem to possess a special structure which defines a sub-class of oncofetal HNK-1 glycans. The over-expression of the glycoprotein ligands of these lectins in most transformed cells provides new tools for understanding the underlying mechanism of malignant transformation as well as the generation of signals through cell adhesion.

Animals↗
PubMed1992

Somatic sympathetic vasomotor changes documented by medical thermographic imaging during acupuncture analgesia.

Acupuncture is widely used for pain relief in many musculoskeletal disorders, and evidence suggests that modulation of the sympathetic nervous system responses which play an integral part in somatic pain, is an important mechanism of acupuncture action. This prospective study of 20 patients with neck and arm pain measured finger temperature, controlled by somatic sympathetic vasomotor activity before and after needle acupuncture. Responses were correlated with visual analogue scale (VAS) of pain severity. An association was found between pain relief and reduced sympathetic vasomotor activity. In 10 patients with significant reduction in visual analogue scale (VAS) pain (p less than .05), the mean change in temperature (delta t degrees C) was 0.55 (SD +/- 0.86) with significant difference in pre to post treatment temperatures (p less than .01). In 10 patients without significant pain relief on VAS scoring (p greater than .05), the mean t degrees C was 0.20 (SD +0.72) without significant difference in pre to post treatment temperatures (p greater than .05). The relevance of somatic sympathetic influences on musculoskeletal pain and modulation of sympathetic activity by acupuncture will be discussed.

Acupuncture Analgesia↗
PubMed1992

Expression of RNA isolated from the water-shunting complex of a sap-sucking insect increases the membrane permeability for water in Xenopus oocytes.

The highly specialized membranes of the filter chamber found in the digestive tract of some homopteran insects could represent a favorable material for characterizing water channels. In order to demonstrate that membrane proteins of this epithelial complex serve as water channels, we have investigated the membrane permeability for water in Xenopus oocytes injected with RNA isolated from the filter chamber. Volumes of oocytes injected with filter chamber RNA were increased by 15% following a 16-min osmotic shock, while volumes of oocytes injected with RNA from midgut not of filter chamber or with water were increased only by 8.5 and 10%, respectively. This significant difference in oocyte swelling leads us to conclude that RNA isolated from the filter chamber contains mRNA coding for water channel proteins.

Animals↗
PubMed1992

Carotid stenosis is a powerful predictor of a positive exercise electrocardiogram in a large hyperlipidemic population.

Hypercholesterolemia is a major risk factor in coronary heart disease (CHD) and ischemic stroke. However, there is no general agreement on the usefulness of systematic screening of patients with hyperlipidemia by stress exercise electrocardiogram (ECG). The feasibility of this approach would depend on selecting patients with a high risk of CHD, since the sensitivity and specificity of the test depends on the prevalence of the disease. In view of the association of CHD and ischemic stroke, we undertook a study to determine whether the presence of atherosclerosis in the carotid arteries was predictive of a positive exercise ECG in a group of 778 asymptomatic patients referred to their hyperlipidemia. We a much higher percentage of positive exercise ECG in patients with carotid atherosclerosis in our ultrasonographic examinations. In a multiple regression analysis which included 13 parameters (age, sex, body mass index, arterial blood pressure, lipid parameters, serum level of glucose, smoking status and the severity of carotid lesions), the strongest predictors of a positive exercise ECG test were age (P = 0.014) and the degree of carotid atherosclerosis (P = 0.010). We therefore conclude that hyperlipidemic patients with atherosclerotic lesions on carotid arteries would benefit most from screening by the exercise ECG.

Adult↗
PubMed1992

Radiotherapy of malignant subdiaphragmatic implants in advanced ovarian carcinoma: a new technique.

We report the development of a new technique using remote afterloading intraoperative radiation therapy to deliver a tumoricidal dose to diaphragmatic tumor implants. A multi-positional lucite applicator was designed based on anatomic studies of the diaphragmatic surface to accommodate a high dose rate iridium source in a series of needles placed 1.5 cm apart. The applicator curvature can vary from planar to full accommodation of the diaphragmatic surface with a constant source to surface distance of 0.5 cm. The applicator has been piloted in three patients with ovarian carcinoma with residual subdiaphragmatic disease found at second look laparotomy, to deliver a dose of 1,500 to 2,000 cGy at 0.5 cm. Tolerance of the diaphragm and hepatic surface has been excellent. There were no postoperative complications and no deterioration in liver function studies. The additional postoperative external beam irradiation directed with the aid of surgically placed clips and gated to respiratory movements permits achievement of a tumoricidal dose while limiting the treated volume and related toxicities.

Brachytherapy↗
PubMed1992

Renal hemodynamics in newly presenting non-insulin dependent diabetes mellitus.

Little information is available regarding renal hemodynamics in non-insulin dependent diabetics (NIDDMs), despite their numerical significance to renal support programs. Therefore, simultaneous determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) (expressed to 1.73 m2 surface area) was performed in 110 newly presenting normotensive NIDDMs [mean (SD) age: 52.5 (10.1) years] and compared with 32 normal subjects of similar age range [age: 52.2 (11.3) years]. Mean (SD) GFR, ERPF and filtration fraction (FF) for the NIDDMs were: 117 (22) ml/min (range: 74 to 178), 534 (123) ml/min and 22.4 (3.0)%, and for the normals: 95 (12) ml/min (range: 75 to 119), 472 (70) ml/min and 20.2 (2.2%), respectively. As a group, NIDDMs demonstrated significantly greater GFR (P less than 0.001), ERPF (P less than 0.005) and FF (P less than 0.001). GFR values above 140 ml/min were observed in 16% of the NIDDMs, while 45% had GFRs in excess of mean +/- 2 SD of the normals. NIDDMs demonstrated a positive relationship for GFR with ERPF (P less than 0.001) and an inverse association for both GFR and ERPF with age (P less than 0.001). Multivariable regression analysis revealed ERPF as the strongest explanatory variable for GFR in the NIDDMs (P less than 0.001), followed by age (P less than 0.01). Significant contributions to the regression analysis were not observed for body mass index, systolic or diastolic blood pressures, glycosylated hemoglobin nor fasting levels of plasma glucose, cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides. Urinary albumin excretion rates were not correlated with GFR, ERPF or FF. Microalbuminuria was detected in 7% of the NIDDMs in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus, Type 2↗