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Biomedical subjects

S Larson

Publications and source records attributed to S Larson.

At least 55 records · Page 3Linked to original sources
PubMed1991

The febrile alcoholic in the emergency department.

The authors retrospectively reviewed the charts of 31 alcoholic patients admitted with fever without a defined source. In our population 58% of patients were subsequently found to have an infectious cause for their fever. Pneumonia was the most common infection, but occult urinary tract infections were seen surprisingly often. Noninfectious but serious disorders, such as delirium tremens, prolonged postictal state, and subarachnoid hemorrhage, were also common. Infectious and noninfectious causes commonly coexisted. The most common noninfectious cause was alcohol withdrawal, with or without seizures. The authors believe that indigent, malnourished, chronic alcoholics with fever for which a source cannot be readily identified, should usually be admitted to the hospital for observation and to await culture results.

Adult↗
PubMed1988

Problems associated with collecting drinking water quality data for community studies: a case example, Fresno County, California.

This paper discusses methodology in developing exposure data for the water supply contaminant dibromochloropropane (DBCP) in Fresno County, California. There are 532 drinking water systems (49 large and 483 small) within Fresno County plus 14,000 private wells. We determined the number of wells per system, the output per well, and the population served by each system. The task of deriving water quality estimates for each census tract was complicated by the fact that a single census tract can be served by more than one system; each system usually has more than one well; and a single well can have several episodes of testing for various contaminants. We calculated a series of weighted averages for concentrations of DBCP, arsenic, and nitrates for each census tract, using water production figures for each well as the weighting factor. Water quality data were derived from a total of 14,861 laboratory reports, although the majority did not report on all contaminants. Mean DBCP levels ranged from 0.0041 ppb to 5.7543 ppb among the census tracts. We found no correlation between DBCP levels per census tract compared to either arsenic or nitrates. We believe that we made as complete an exposure assessment as practically feasible.

Arsenic↗
PubMed1987

Cerebral glucose metabolism in the Lennox-Gastaut syndrome.

We used positron emission tomography with fluorine 18-labeled 2-deoxyglucose to study cerebral glucose metabolism in 10 patients with Lennox-Gastaut syndrome who had normal neuroradiological studies. The scans showed decreased metabolic rates relative both to those in the caudate nucleus and to normal control values in 3 patients whose seizures began before the age of 1, as well as in a patient with hyperprolinemia. No patient had a region of persistent focal hypometabolism. Metabolic rates increased in parallel with increased electroencephalographic discharges in 1 patient; 3 patients had lower metabolic rates when the electroencephalogram showed epileptiform discharges and while the patients were taking barbiturates.

Adolescent↗
PubMed1987

125I-iodinated benzazepines bind to melanin: implications for the noninvasive localization of pigmented melanomas.

Both the 5-R and the 5-S enantiomers of [125I]2,3,4,5-tetrahydro-8-iodo-3-methyl-5-phenyl-1H-3-benzazepin- 7-ol bind to melanin. The interaction between the 5-R enantiomer and melanin permits visualization of melanomas in mice with a noninvasive imaging procedure. Two lines of evidence suggest that the interaction between iodinated ligands and melanin is not related to the D-1 dopamine receptor, a known target for the 5-R enantiomer: first, melanin binds both enantiomers of the 125I-iodinated benzazepine while the D-1 receptor binds only the 5-R enantiomer; second, the melanin binding site displays only a 5-fold difference in affinity towards the R- and S-enantiomers of SCH 23390 while the D-1 receptor displays a 100-fold difference in affinity towards these two molecules. Because both enantiomers of the iodinated benzazepine bind to a human pigmented melanoma, we propose that such compounds may be of use in the diagnosis of pigmented melanoma: in addition, we discuss the possible application of these molecules as a supplement to existing technology for the localization of pigmented melanomas.

Animals↗
PubMed1987

Erythrocyte Na+-K+ ATPase activity in childhood: regulation by genetic factors independent of body weight.

A number of previous investigations in obese and normal-weight adults suggested a link between (usually) lower than normal erythrocyte Na+-K+ ATPase activity and obesity, although more recent studies have disputed this link. Developmental patterns of ATPase activity in children have not been studied. Infants of diabetic mothers show an increased incidence of macrosomia and such infants are at risk for later development of obesity. These children provide an ideal group to study the link (if any) between this enzyme and obesity, as well as changes in the level of the enzyme which may occur with age and/or the onset of obesity. The Na+-K+ ATPase levels in erythrocytes from 87 normal children and 27 infants of diabetic mothers were therefore studied by an ouabain-binding method. The study populations contained representatives of three ethnic groups (black, Caucasian and Hispanic) and individuals of normal body weight, as well as overweight and obese individuals. The ATPase activities were not correlated with body weight, sex, or age, nor was umbilical cord red cell ATPase correlated with birthweight. Several children who are being followed have shown considerable variation in percentage ideal body weight (IBW); however their ATPase levels have remained unchanged. There were, however, significant differences among the ethnic groups, with Caucasians having the highest values (0.443 +/- 0.012 pmol ouabain bound/10(9) cells). These data demonstrate the importance of matching study groups by race when investigating factors affecting this enzyme. The differences among the ethnic groups suggest a genetic component in the determination of the activity of this enzyme. This link was further investigated in 14 families and revealed considerable heterogeneity within a given ethnic group, with family members generally having similar enzyme activities, thus supporting a genetic basis for the different enzyme levels. Thus erythrocyte Na+-K+ ATPase in childhood is primarily regulated by genetic factors which are generally independent of body weight.

Black People↗
PubMed1986

Effect of phenytoin on human cerebral glucose metabolism.

We used serial positron emission tomography scans with [18F]2-deoxyglucose to study the effect of phenytoin on human cerebral glucose metabolism in 10 patients with seizure disorders. Local CMRglu for each patient was measured in 10 regions of interest. EEGs were performed during each procedure to match scans for state of consciousness and exclude data from scans with ictal activity. Serial scans without a drug change were performed in six control patients. Metabolic rates were significantly lower in two cortical regions while patients were taking phenytoin. No significant changes on repeat scan were seen in the control population. Measured across all regions of interest, metabolic rates were 13% higher when patients were off phenytoin (p less than 0.02).

Adult↗
PubMed1986

Positron emission tomography in Alzheimer's disease.

Twenty-one patients with a clinical diagnosis of dementia of the Alzheimer's type (DAT) and 29 healthy, age-matched controls were studied using positron emission tomography (PET) and [18F]2-fluoro-2-deoxy-D-glucose to measure regional cerebral glucose consumption in the resting state. Reductions in ratio measures of relative metabolism in some parietal, temporal, and frontal regions were found in mild, moderate, and severe DAT groups. A significant increase in right/left metabolic asymmetry, particularly in parietal regions, also was seen in mild and moderate groups. Only in the severely demented patients was the absolute cerebral metabolic rate reduced significantly from control values. Fourteen patients had repeated PET studies, but only those patients with moderate to severe dementia showed a decline in IQ over 6 to 15 months. There were no significant changes in metabolic measures over time. PET is useful in quantifying regional cerebral dysfunction in DAT, even in the early stages of the disease.

Aged↗
PubMed1985

Sexual dimorphism in the postcranial skeleton of New World primates.

This study examines sexual dimorphism in 24 dimensions of the postcranial skeleton of four platyrrhine species: Callithrix jacchus, Saguinus nigricollis, Saimiri sciureus, and Cebus albifrons. The two callitrichid species show a relatively small amount of variation in the degree of sexual dimorphism among the different dimensions. Variation is considerably higher in the two cebid species as reflected by a mosaic pattern of sexual dimorphisms with males being significantly larger than females in some dimensions, and females significantly larger than males in others. In dimensions of the pectoral girdle and limb bones, males and females in each of the two cebid species are essentially scaled versions of each other, with males being peramorphic compared to females. This pattern is primarily the result of time hypermorphosis, i.e. an extension of the growth period in time in males. Rate hypermorphosis, i.e. an increase in the rate of growth in time in males, appears to play an additional role, however, in S. sciureus. By contrast, in dimensions of the true pelvis, sex differences in shape are dissociated from those in size. They are interpreted as the result of acceleration, i.e. increase in rate of shape change in females, as an adaptation to obstetrical functions. Interspecific analyses indicate positive allometry of mean degree of postcranial dimorphism with respect to body size. This coincides with previous findings by Leutenegger and Cheverud [1982, 1985] on the scaling of sexual dimorphism in body weight and canine size, and thus supports their model which posits selection on body size as the prime mover for the evolution of sexual dimorphism.

Aging↗