Biomedical subjects
R Thompson
Publications and source records attributed to R Thompson.
Results of a randomized feasibility study of a low-fat diet.
A 2-year randomized clinical trial was conducted to test whether free-living women aged 45 to 69 years can reduce the fat content of their diet from the typical US level of approximately 39% to 20% of energy from fat, using readily available foods, when given nutritional and behavioral counseling and social support. Three clinical units randomized 303 selected volunteers into intervention (low-fat eating plan) or control (customary diet) groups. The two groups were comparable at baseline. The intervention group received nutrition instruction and behavioral counseling largely in permanent groups of 12 to 15 participants meeting weekly, then biweekly, and finally monthly. At 6 months, they had substantially reduced the mean proportion of total energy from fat from 39.1% to 20.9%, compared with the control group's nonsignificant reduction from 39.0% to 38.1%. At 12 and 24 months, they sustained the reduction of energy from fat. Weight loss and plasma cholesterol level changes in the intervention group supported the self-recorded dietary intake changes. Attendance at intervention sessions averaged 75% during the first 6 months and, subsequently, 60% to 70%. Four-day food records for the randomized women were obtained at 6 and 12 months from approximately 95% and at 24 months from 87%. A clinical trial of a low-fat diet is feasible in women.
The sequence of the zein regulatory gene opaque-2 (O2) of Zea Mays.
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The O2 gene which regulates zein deposition in maize endosperm encodes a protein with structural homologies to transcriptional activators.
The structure of the zein regulatory gene Opaque 2 of Zea mays has been determined by sequence analysis of genomic and cDNA clones. The size of O2 mRNA is 1751 bp [poly(A) tail not included] containing a major open reading frame (ORF) of 1380 bp preceded by three short ORFs of 3, 21 and 20 amino acid residues. The main ORF comprises 1362 bp and is composed of six exons ranging in size from 465 to 61 bp and five introns of 678 bp to 83 bp. A putative protein 454 amino acids long was derived by the theoretical translation of the genomic sequences corresponding to exons. The opaque 2 protein contains a domain similar to the leucine zipper motif identified in DNA binding proteins of animal protooncogenes such as fos, jun and myc, and in the transcriptional activators GCN4 and C/EBP. The region of 30 amino acid residues next to the leucine repeats towards the N terminus is rich in basic amino acids and is also homologous to a domain present in fos, jun and GCN4. Moreover, in the carboxy terminal region an amino acid motif closely resembling a metal binding domain is present.
Molecular characterization of an active wheat LMW glutenin gene and its relation to other wheat and barley prolamin genes.
The isolation and characterisation by DNA sequencing of a low molecular weight (LMW) glutenin gene from wheat is described. The deduced protein contains a signal peptide, a central repetitive region rich in proline and glutamine and N and C terminal non-repetitive domains, similar to other prolamins. A detailed comparison of the C terminal domain of 20 prolamin genes enabled us to divide them into 4 families. The LMW glutenin family is distinct from the alpha, beta- and gamma-gliadin families of wheat and is closest to the B hordein genes of barley. This and other comparisons were also used to assess the pattern of genetic variation among prolamin sequences and to provide a molecular basis for the interpretation of prolamin size polymorphism. The 5' flanking fragment of the isolated gene was previously shown to direct endosperm-specific expression of a reporter gene in transgenic tobacco. Evidence is provided that the isolated gene is also active in wheat and its transcription initiation site was determined. Features of the gene which may be relevant to its activity are discussed.
Failure to transfer a digging response to a detour problem in young rats with lesions to the "general learning system".
Recent lesion studies on young rats suggest that the components of the rodent's general learning system (GLS; a group of brain structures essential for normal acquisition of a wide range of laboratory tasks, include the regions of the caudatoputamen, globus pallidus, ventrolateral thalamus, substantia nigra, ventral tegmental area, superior colliculus, median raphe, and pontine reticular formation). The current study provides evidence that young GLS-lesioned rats, like mentally retarded humans, may be suffering from a disturbance in some superordinate ability (executive functioning) that controls the use of learning strategies in general and the transfer of learning in particular. Specifically, thirsty rats were initially trained to traverse a narrow runway to reach a goal box containing water. When a portion of the runway was blocked with sawdust, all of the sham-operated control rats succeeded in burrowing through the sawdust to gain access to the goal box, whereas most of our GLS-lesioned rats failed to do so even though they "knew how" to dig. Neocortically damaged rats showed a similar though significantly smaller deficit. Although other interpretations are possible, these data give tentative support to the view that this impairment in transfer reflects a defect in executive processing.
Learning ability in young rats with single and double lesions to the "general learning system".
Previous lesion studies suggest that the dorsal caudatoputamen (DCP), globus pallidus, ventrolateral thalamus (VLT), substantia nigra, ventral tegmental area, superior colliculus (SC), median raphe, and pontine reticular formation are components of the general learning system (GLS) of the rat brain. The current study attempted to determine whether bilateral lesions to two components of the GLS (DCP/VLT, DCP/SC or VLT/SC) would produce greater deterioration of learning ability than bilateral lesions to only one component (DCP, VLT or SC). In all combinations examined, a second lesion added to the first led to a significantly greater learning decrement on a series of spatial reversal problems than that associated with the first lesion alone. These results are compatible with the view that the foregoing structures are elements of the same functional system concerned either directly or indirectly with general learning ability.
Screening for congenital adrenal hyperplasia: distribution of 17 alpha-hydroxyprogesterone concentrations in neonatal blood spot specimens.
In a retrospective analysis of 24 cases of congenital adrenal hyperplasia (CAH) in neonates born in the province of Manitoba during the last 20 years, we set out to determine whether patients, in particular male infants with salt-losing CAH, were being missed by the usual forms of clinical ascertainment. Although the overall incidence of 1/14,500 live births was similar to that found in several screening surveys, a skewed female/male sex ratio of 2.2:1 suggested probable death among male infants with unrecognized adrenal insufficiency. These results led to a prospective analysis of 17 alpha-hydroxyprogesterone (17-OHP) levels in 1194 neonatal blood specimens by a solid-phase direct radioimmunoassay procedure to determine whether this method would be suitable for CAH screening. In 1103 neonates weighing greater than 2500 gm at birth, all 17-OHP values were less than 30 nmol/L (approximately 1000 ng/dl), with a mean of 8.2 nmol/L; values in male infants were slightly higher than in female infants. In 89 neonates with a birth weight less than 2500 gm, 17-OHP values were skewed, with nine having levels greater than 30 nmol/L and two greater than 50 nmol/L. Postnatal age (1 to 24 days) at the time of specimen collection had no effect on 17-OHP levels, although higher values occur during the first 24 hours. One unsuspected case of CAH in a male infant was discovered during the trial period. We conclude that neonatal CAH screening can permit diagnosis and therapy of affected male infants who are being missed by normal clinical evaluation. This radioimmunoassay method is relatively simple and inexpensive, and it has the specificity and sensitivity necessary to provide such mass screening.
Percutaneous transthoracic needle aspiration lung biopsy in the community hospital.
In 108 cases in which transthoracic needle aspiration biopsies were studied at Raleigh General Hospital in Beckley, West Virginia, from 1983 through 1987, the pathologic diagnoses were compared and correlated with the subsequent clinical course. The procedure was performed under C.T. guidance. Correlation of pathology with the clinical course yielded 67 per cent (72 cases) true positives, 19 per cent (20 cases) true negatives, four per cent (four cases) false negatives, zero per cent (zero cases) false positives, and 11 per cent (12 cases) indeterminates. In 23 per cent of the cases, there were radiologically demonstrated pneumothoraces, with placement of a chest tube required in 12 per cent of the cases. Hemoptysis occurred in eight per cent of the patients. The results confirmed the appropriateness of using transthoracic needle aspiration biopsies at this hospital.
Newborn screening for galactosemia: a new method used in Manitoba.
In July 1983, the Manitoba Perinatal Screening Programme modified its existing procedure for neonatal screening for galactosemia by introducing quantitation of total galactose plus galactose-1-phosphate from dried blood spots using the Multistat centrifugal analyzer. The first 4 years of experience with this method in combination with the Beutler spot test for galactose-1-phosphate uridyl transferase activity is the subject of this report. Of 70,336 newborns screened, 142 (0.20%) met the criteria for clinical follow up. Of these, one child was confirmed to have classical galactosemia and nine children were found to be Duarte/galactosemia genetic compounds. This method of galactosemia screening has proven to be rapid, sensitive, efficient, and the method of choice for mass screening of disorders of galactose metabolism.
Evidence for hippocampal regulation of neuroendocrine neurons of the hypothalamo-pituitary-adrenocortical axis.
Expression of mRNAs coding for the ACTH secretagogues corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) was examined in the hypothalamic paraventricular nucleus (PVN) of rats bearing hippocampal lesions. Either total hippocampectomy (HPX) or extirpation of the dorsal hippocampus (DHPX) precipitated a 4-fold increase in CRF mRNA expression relative to sham-operated controls (SHAM), as determined by semiquantitative in situ hybridization histochemistry. AVP mRNA was localized to individual parvocellular neurons of the medial parvocellular division of the PVN in only the HPX and DHPX groups, consistent with enhanced production of AVP message in this neuronal population subsequent to hippocampal damage. HPX did not affect AVP mRNA content in magnocellular divisions of PVN. Plasma beta-endorphin levels were significantly elevated in the HPX and DHPX groups relative to SHAM animals, indicating a chronic increase in release of proopiomelanocortin peptides from the anterior pituitary gland in response to hippocampal lesion. Circulating corticosterone levels were elevated in HPX rats as well. To control for effects of lesion size and location, additional animals received large ablations of cerebral cortex or cerebellum. In neither case was CRF or AVP mRNA significantly altered in the PVN. The results suggest that the hippocampus exercises a tonic inhibitory role on ACTH secretagogue production in neuroendocrine neurons promoting ACTH release.
Low-dose aspirin improves fetal weight in umbilical placental insufficiency.
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A focal point for advice on buying.
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Sexual activity in the young.
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Correlation of dopant-induced optical transitions with superconductivity in La2-xSrxCuO4- delta.
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Learning ability of young rats is unaffected by repeated exposure to a static electromagnetic field in early life.
Infant albino rats were exposed to a static electromagnetic field of 0.0 Tesla (control) or 0.5 Tesla (experimental) for 14 postnatal days. Following a 1-month rest period, the experimental (13 males and 10 females) and control (11 males and 14 females) rats were trained on four successive reversals of a position habit in a single-unit enclosed T-maze that was adapted for the use of escape-avoidance of mild foot shock as a motive. There was no significant difference in learning ability between the experimental and control groups in terms of total (initial combined with repetitive) errors committed over the four reversal problems. While the females tended to make more errors than the males, this difference was likewise insignificant.
Case report 460: Synovial chondrosarcoma of left knee.
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Seasonal, geographic and individual variation of okadaic acid content in cultivated mussels in Sweden.
In Western Europe the dinoflagellate toxin, okadaic acid (OA) has been the main cause of diarrheic shellfish poisoning (DSP). Chemical determination of OA in mussels by homogenization of the hepatopancreas, extraction, purification, reaction with 9-anthryldiazomethane (ADAM), HPLC-separation, and fluorometric quantification has been used for weekly monitoring of mussel growing farms and to control harvested mussels. Within a week, substantial rises (from 0.41 to 5.4 micrograms OA/g hepatopancreas) as well as great reductions (from 7.2 to 1.8 micrograms/g hepatopancreas) were recorded. The rapid rise implies that weekly sampling is not sufficient to ensure that mussels are free from toxic levels of OA. The rapid decrease reveals that efficient toxin clearance mechanisms exist in the mussels. Substantial OA clearance occurs also at low temperatures (1.4-3 degrees C). Within a mussel growing site the OA concentrations could differ considerably between adjacent mussels (0.63 and 4.2 micrograms OA/g hepatop.) and even more between mussels grown at different depths along the same rope (0.63 and 10 micrograms OA/g hepatop.). These data emphasize the importance of sampling in studies on DST in mussels. Great differences between the different mussel growing sites were also observed. These data have been discussed with respect to the spread of the toxin by the sea, and the possibilities of reducing the exposure of the mussels to the toxic algae.