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Biomedical subjects

A Thomas

Publications and source records attributed to A Thomas.

At least 613 records · Page 34Linked to original sources
PubMedDate not supplied

Fetal growth and body composition in infants of women with diabetes mellitus during pregnancy.

The purpose of this study was to evaluate growth velocities of various neonatal tissues in women with diabetes mellitus. We hypothesize that in large for gestational age (LGA) infants, insulin-sensitive tissue will demonstrate the greatest accelerated growth. Thirty-eight singleton pregnancies had prospective longitudinal ultrasound measurements of the fetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), transcerebellar diameter (TCD), liver length, renal length, abdominal fat, and thigh fat in late pregnancy. At birth, neonatal body composition was estimated and anthropometric measurements were obtained. Twenty-four neonates were not large for gestational age (non-LGA) and 14 LGA based on birth weight percentile > or = 90 percentile. The fetal AC (P = 0.0006), liver length (P = 0.01), thigh fat (P = 0.02), and abdominal wall fat (P = 0.001) demonstrated accelerated growth velocity in LGA fetuses. At birth LGA infants had a 17% (P = 0.0001) increase in lean body mass, but a 99% (P = 0.0001) increase in fat mass compared with non-LGA infants. Using stepwise regression, abdominal wall fat accounted for 63% (P = 0.0001) of the variance in AC compared with 3% (P = 0.13) for liver length. In conclusion, ultrasound estimates of adiposity may potentially be a sensitive indicator of growth abnormalities in infants of diabetic women in late gestation.

Abdomen↗
PubMedDate not supplied

Incidental magnetization transfer contrast in fast spin-echo imaging of cartilage.

In this article, the authors illustrate the contributions of incidental magnetization transfer contrast (MTC) to the signal characteristics of patellar cartilage on routine, multiplanar fast spin-echo (FSE) images. Incidental MTC diminishes the signal of patellar cartilage by 30% on routine FSE scans. Spectral fat saturation does not significantly increase incidental MTC on multislice FSE acquisitions. By increasing the contrast between synovial fluid and patellar cartilage, incidental MTC may account for greater conspicuousness of chondromalacia on FSE as compared to conventional spin-echo images. Incidental MTC may also alter or obscure the normal, laminar appearance of hyaline cartilage on short-TE, FSE images.

Cartilage, Articular↗
PubMedDate not supplied

Coil embolization of a solitary congenital intrahepatic hepatoportal fistula.

Congenital hepatic artery-to-portal vein fistula, a rare type of arteriovenous malformation that may be intrahepatic or extrahepatic, is an uncommon cause of severe infantile portal hypertension. Many researchers believe that acquired intrahepatic arterioportal fistulas are best treated by embolization and that extrahepatic arterioportal fistulas require surgical intervention. The experience with congenital intrahepatic arterioportal fistulas is very limited and has required both embolization and surgical intervention. We report a case of solitary congenital arterioportal fistula successfully treated with coil embolization.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Extracellular pH defense against lactic acid in normoxia and hypoxia before and after a Himalayan expedition.

The extracellular pH defense against the lactic acidosis resulting from exercise can be estimated from the ratios -delta[La].delta pH-1 (where delta[La] is change in lactic acid concentration and delta pH is change in pH) and delta[HCO3-].delta pH-1 (where delta[HCO3-] is change in bicarbonate concentration) in blood plasma. The difference between -delta[La].delta pH-1 and delta[HCO3-].delta pH-1 yields the capacity of available non-bicarbonate buffers (mainly hemoglobin). In turn, delta[HCO3-].delta pH-1 can be separated into a pure bicarbonate buffering (as calculated at constant carbon dioxide tension) and a hyperventilation effect. These quantities were measured in 12 mountaineers during incremental exercise tests before, and 7-8 days (group 1) or 11-12 days (group 2) after their return from a Himalayan expedition (2800-7600 m altitude) under conditions of normoxia and acute hypoxia. In normoxia -delta[La].delta pH-1 amounted to [mean (SEM)] 92 (6) mmol.l-1 before altitude, of which 19 (4), 48 (1) and 25 (3) mmol.l-1 were due to hyperventilation, bicarbonate and non-bicarbonate buffering, respectively. After altitude -delta[La].delta pH-1 was increased to 128 (12) mmol.l-1 (P < 0.01) in group 1 and decreased to 72 (5) mmol.l-1 in group 2 (P < 0.05), resulting mainly from apparent large changes of non-bicarbonate buffer capacity, which amounted to 49 (14) mmol.l-1 in group 1 and to 10 (2) mmol.l-1 in group 2. In acute hypoxia the apparent increase in non-bicarbonate buffers of group 1 was even larger [140 (18) mmol.l-1]. Since the hemoglobin mass was only modestly elevated after descent, other factors must play a role. It is proposed here that the transport of La- and H+ across cell membranes is differently influenced by high-altitude acclimatization.

Acclimatization↗
PubMedDate not supplied

Gene survival in isolated populations: the number of distinct genes on Tristan da Cunha.

Gene extinction probabilities over the ancestral genealogy of Tristan da Cunha are analysed, to determine the probability distributions of numbers of surviving distinct founder genes. Autosomal, X-linked and Y-linked genes are considered, and also the bivariate distributions of genes originating in males and in females. One founder group shows a greater variety of surviving genes than another, although there is little difference in their total genetic contributions. This excess variety is concentrated in male lines of descent. The paper demonstrates the types of analysis that can be used to illuminate and summarize lists of gene extinction probabilities.

Atlantic Islands↗
PubMedDate not supplied

Classifying, identifying and enumerating arbitrary relationships.

In studies of human genetic isolates, or pedigrees, it is often required to examine the relationships that exist between two individuals in the isolate. This may be of interest in connection with inbreeding, or in its own right, for example in the study of mating patterns. A scheme is developed for classifying any relationship between two individuals in a pedigree as a pair of integers. Relative to a common ancestor, the first integer counts the level of the relationship and the second the difference in generation between the individuals. The scope of this scheme is broad enough to encompass cases of multiplicity of relationships and half-relationships. An algorithm for counting the number of times a given relationship occurs between two individuals is outlined. This algorithm assumes that recursion is possible and that the information on the pedigree is stored in such a way that the parents of an individual can be readily traced. It has been implemented in Algol 68 and in C. The method is illustrated by an example from the complex Samaritan pedigree.

Adult↗
PubMedDate not supplied

Administration of long-term estradiol and progesterone followed by progesterone withdrawal does not alter the plasma oxytocin secretory response to cholecystokinin or the pituitary oxytocin content in ovariectomized rats.

The hormone oxytocin (OT) is important for several pre- and postpartum events, including uterine contractions at parturition, the induction of maternal behavior, and milk ejection during nursing. During late pregnancy, OT mRNA is increased in the paraventricular nucleus (PVN) due to high estrogen and declining progesterone levels. Administration of sequential estrogen and progesterone to, followed by withdrawal of progesterone from, an ovariectomized rat also increases OT mRNA. However, pituitary OT peptide is not affected. In the present experiment, we determined if this steroid exposure alters peripheral OT secretion during a provocative stimulus to OT release, such as cholecystokinin (CCK). Adult ovariectomized Sprague-Dawley rats were implanted on day 1 with either estrogen or empty silastic capsules, on day 3 with progesterone or empty capsules, and on day 14 progesterone or empty capsules were removed. Forty-eight hrs after removal of the progesterone capsules, plasma OT was measured before and after i.v. injection of 10 micrograms/kg of CCK. At the completion of the study, pituitary glands were removed and OT peptide was measured. No significant differences were found between the sham and hormone-treated animals either in their basal or CCK-stimulated plasma OT levels or their pituitary content of OT peptide. Although sequential exposure to estradiol and progesterone followed by withdrawal of progesterone has been shown previously to increase PVN OT mRNA, neither pituitary OT immunoreactivity nor basal and CCK-stimulated release of plasma OT is affected by this treatment. Although the mechanism of this steroid effect is not yet understood, our observations suggest a unique action of gonadal steroids upon PVN OT neurons.

Animals↗
PubMedDate not supplied

Donepezil, rivastigmine, and vitamin E in Alzheimer disease: a combined P300 event-related potentials/neuropsychologic evaluation over 6 months.

The latency of P300 "cognitive" event-related potentials changes if cholinergic activities of the central nervous system are pharmacologically manipulated. We tested the hypothesis that the new cholinesterase inhibitors donepezil (DPZ) and rivastigmine (Riv) may have an effect on the frequently abnormal P300 component in patients with Alzheimer disease (AD), thereby allowing a significant evaluation of cholinesterase inhibitors. We evaluated 60 patients with mild to moderately severe probable AD, in comparison with 60 age-matched control subjects, with P300 recordings and neuropsychologic examinations. Forty patients were randomly assigned in a double-blinded trial to 5-10 mg/d DPZ versus 2,000 IU/d vitamin E, and 20 patients were instead treated in an open trial with 1.5 to 12 mg/d Riv. In patients treated with vitamin E, we observed latency increments (7.4 +/- 3.5 msec) correlated with worsening neuropsychologic test scores. In patients treated with DPZ and Riv, we found significant P300 latency reductions (15.3 +/- 3.2 msec and 22.0 +/- 3.3 msec). Shorter P300 latencies were associated with higher Wechsler Adult Intelligence Scale scores and with lower AD Assessment Scale-cognitive subscale (ADAS-cog) scores (R = 0.72). Correlations between ADAS-cog changes and P300 changes significantly separated patients treated with DPZ and Riv from those treated with vitamin E. Administration of DPZ and Riv reduced the latencies of P300 components proportionately to neuropsychologic test improvements. Combined P300 and neuropsychologic test evaluation significantly separated DPZ-treated patients and Riv-treated patients from vitamin E-treated patients.

Aged↗
PubMedDate not supplied

Clinical correlation of neuropsychological tests with 1H magnetic resonance spectroscopy in hepatic encephalopathy.

OBJECTIVE: The purpose of this project was to correlate neuropsychological test results with in vivo measures of regional cerebral biochemistry determined by 1H MRS in patients with subclinical and mild hepatic encephalopathy. METHODS: Baseline 1H MRS scans and neuropsychological testing of patients occurred at entry into the study. The primary localized volume chosen for the 1H MRS study was the posteromedial parietal cortex, which consisted predominantly of white matter. Some of these patients were scanned again if they received a liver transplantation. In a subset of patients, the effect on cerebral biochemistry and neuropsychological test performance due to a dietary intervention of reduced protein intake was monitored. These patients underwent a baseline examination and a repeat examination after 2 weeks of dietary intervention. Measures were made of the correlation between the dietary intervention and 1H MRS determined biochemistry and the results of neuropsychological tests. Results in both patient groups (dietary intervention and no dietary intervention) were compared with healthy control subjects. RESULTS: Subclinical and low grade HE patients showed a significant reduction in mI/Cr and Cho/Cr ratio when compared with healthy control subjects. These patients also showed impairment in frontal lobe mediated cognitive tasks and in motor ability that were not appreciated in a bedside examination. The patients did not return to normal cerebral metabolic states within 30 to 60 days of liver transplantation. In fact, reductions remained in mI/Cr. Cho/Cr values increased after transplantation compared with healthy control subjects. CONCLUSIONS: 1H MRS studies showed changes in regional cerebral biochemistry associated with all grades of HE. There was a reduction in mI/Cr and a reduction in Cho/Cr in patients with low grade and subclinical forms of HE compared with normal subjects. The reduction in mI correlated well with abnormalities observed in neuropsychological tests. Liver transplantation was not associated with significant improvement in these variables.

Acetylcholine↗
PubMedDate not supplied

Factors which influence the oral condition of chronic schizophrenia patients.

The oral health status of 249 individuals with chronic schizophrenia was evaluated by means of the Oral Hygiene Index (OHI-S) and Decayed, Missing and Filled Teeth scores (DMFT). The patients were subdivided as to chronicity of illness and venue of psychiatric treatment (158 inpatients > 10 years' hospitalization, 34 inpatients < 10 years' hospitalization, and 57 outpatients). The severity of schizophrenia was determined by: the Brief Psychiatric Rating Scale (BPRS), the intensity of negative symptoms of schizophrenia [as measured by the Brief Psychiatric Rating Scale, Negative Symptoms (BPRSNEGS)], and the equivalent dose of chloropromazine (EDC). This study demonstrated that inpatients had greater amounts of dental disease than outpatients. The extent of dental disease among inpatients as measured by both the OHI-S and DMFT scores was directly related to the intensity of schizophrenia (BPRS), magnitude of negative symptoms associated with schizophrenia (BPRSNEGS), and length of hospitalization. DMFT scores were directly related to EDC value.

Adult↗
PubMedDate not supplied

Fetal tissue dosages of retinoids. Experimental study concerning a case of isotretinoin (Roaccutan) administration and pregnancy.

The authors report the case of a women who took retinoids (Roaccutan, isotretinoin) during the first trimester of pregnancy, and a therapeutic abortion was carried out. The interest in this case report lies in the determination of the concentration of isotretinoin and its metabolites (4-oxo-isotretinoin, and tretinoin) in fetal tissues, using high performance liquid chromatography. The findings show the significant transplacental crossing of isotretinoin, an accumulation of 4-oxo-isotretinoin in the liver, and a low concentration of retinoids in the brain of this 4-month-old fetus. The authors emphasize that contraception must be used during retinoid treatment, and 4 weeks after retinoids have been stopped.

Abortion, Therapeutic↗
PubMedDate not supplied

Stress and other psychosocial characteristics of patients with psychogenic nonepileptic seizures.

Research on psychogenic nonepileptic seizures (PNES) has focused on childhood abuse, but less is known about other stressors and psychosocial risk factors. The authors compared 25 patients with PNES with 33 control subjects with epilepsy on stressful life events and other risk factors for somatoform disorders. Compared with control subjects, patients with PNES reported significantly more prevalent and stressful negative life events (including adulthood abuse) and more current rumination, stress-related diseases, somatic symptoms, bodily awareness, and marginally more anxiety and depression. However, the relationship of many of these variables to PNES was accounted for by life stress. Groups did not differ on illness worry, alexithymia, or psychotic symptoms. The results suggest that PNES are part of a larger pattern of somatic symptoms responses to a wide range of negative events, including stress in adulthood.

Adult↗