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Biomedical subjects

C Weaver

Publications and source records attributed to C Weaver.

At least 55 records · Page 3Linked to original sources
PubMed1992

Effects of physical stress on complete blood count and venous blood gas profile of individuals with sickle cell trait.

The association between sickle cell trait (SCT) and adverse effects of exercise has been controversial. While individuals with SCT are at higher risk of sudden death, the mechanism for this outcome remains to be elucidated. In order to shed light on this controversy, we have monitored venous blood count and blood gas parameter values in normal and SCT subjects during treadmill exercise. White and red blood cell counts and hemoglobin changed significantly over time in both the SCT and normal groups, with peak exercise values different from pre-exercise or post-exercise values. Red blood cell counts showed significant group-time interaction; increase in count during exercise was accentuated in SCT subjects. All blood gas parameters showed significant changes over time in both groups. O2 content was significantly higher in SCT than AA at all time intervals. O2 saturation, pO2 and CO binding to hemoglobin showed significant group-time interaction. Furthermore, O2 saturation for the combined groups was significantly greater at peak exercise and at rest than before exercise. It is possible that treadmill exercise causes microvascular shunting in SCT subjects, leading to a decrease in the peripheral utilization of oxygen.

Adult↗
PubMed1991

Enzymologic studies on patients with methylmalonic aciduria: basis for a clinical trial of deoxyadenosylcobalamin in a hydroxocobalamin-unresponsive patient.

Eleven patients with methylmalonic aciduria have been classified on the basis of detailed enzymology on cultured skin fibroblasts. Nine were classified as mutase deficiencies and were unresponsive to hydroxocobalamin in vivo or in vitro. One was classified as a Cbl A variant and was responsive to hydroxocobalamin therapy in vitro and in vivo. Patient 11 was classified as having deoxyadenosyltransferase deficiency (Cbl B). However, a clinical therapeutic trial of deoxyadenosylcobalamin resulted in no clinical or biochemical improvement. Further studies on the patient's cultured fibroblasts suggested that deoxyadenosylcobalamin fails to reach the mitochondria in an intact form. These studies show that detailed enzymologic classification is essential for the reliable evaluation of the response to therapeutic maneuvers; complementation studies alone may be inadequate to completely classify these patients. Therapy with deoxyadenosylcobalamin offers no advantages over the use of hydroxocobalamin in the treatment of patients with methylmalonic aciduria.

Alkyl and Aryl Transferases↗
PubMed1990

Dieting concerns of 10-year-old girls and their mothers.

The responses of a group of 10-year-old girls on a dietary restraint questionnaire described a wide range of dieting concerns. Subgroups of highly restrained and low-restrained girls were identified and their mothers interviewed. A strong relationship (r = .68) was found between the degree of dietary restraint expressed by the girls and their mothers. The highly restrained girls had a significantly higher EAT score than the low-restrained girls, and shared with their mothers a susceptibility to the disinhibitory effects of negative mood states on their eating behaviour.

Anorexia Nervosa↗
PubMed1990

Divergent post and tube and screw systems for the short crown preparation.

A one-step divergent sliding post incorporated through a crown casting provides effective auxiliary retention for the short crown preparation, especially when interocclusal distance is minimal. With this procedure, retention is gained from the residual walls of both the extracoronal preparation and the canal preparation even though their respective axes may be divergent. A tube and screw attachment may also be incorporated inside and understructure coping to secure a permanently cemented short crown-and-bridge retainer. Both techniques may be used separately or in combination for maximal retention and, despite the additional complexity and cost, will compensate for the short extracoronal walls of the second molar preparation.

Crowns↗
PubMed1989

Absorption of calcium and magnesium from fortified human milk by very low birth weight infants.

Absorption of calcium and magnesium endogenous to human milk, as well as calcium and magnesium added as an exogenous supplement to human milk, was determined in 9 very low birth wt infants. Human milk, intrinsically labeled with stable isotopic tracers of calcium and magnesium, was prepared by administering isotopic tracers intravenously to a lactating woman. Different isotopic tracers, which were representative of calcium and magnesium in the supplement (Enfamil Human Milk Fortifier, Mead Johnson Nutritional Div.), were added to the intrinsically labeled milk. The fortified milk, which was labeled with two calcium tracers and two magnesium tracers, was given orally to the test subjects in a single feeding. True absorption of calcium and magnesium was determined from differences between the doses of tracer ingested and the quantities of tracer excreted in the feces. Stable isotopic tracers were quantified by fast atom bombardment mass spectrometry. These results demonstrate that the fractional absorptions of calcium in the human milk and the added mineral supplement are 80 and 82%, respectively. A total of 89% magnesium endogenous to human milk and 86% of magnesium derived from the mineral supplement was absorbed by the VLBW infants.

Biological Availability↗
PubMed1988

Nonenzymatic isolation and culture of adult islets from atrophic pancreata of copper-deficient rats: a morphologic analysis.

The purpose of this study was to develop a nonenzymatic method of isolating adult islets using atrophied pancreata from copper-deficient rats and to analyze their morphologic characteristics and behavior in culture. This unusual model of isolation was studied because islets remain intact in the course of dietary copper deficiency while the acinar glandular component of the pancreas undergoes selective atrophy and lipomatosis. Small fragments containing islets were readily microdissected from atrophied glands and placed in culture. Within 24 h the fragments congealed into small irregular- to spherical-shaped masses within which the darker profile of islets could be distinguished. Within a period of 3 to 5 d, islet tissue began to bud from the lipocytic mass until by Day 7 spherical aggregates of intact islet tissue separated from the residual fragments. Subsequent to further in vitro treatment, these islets could be maintained as free viable spherical masses if periodically agitated, as attached stationary islets which developed monolayer growth if left undisturbed and as aggregated masses of islet tissue forming megaislets if combined in small groups. Grouped islets treated with actinomycin D and cycloheximide did not exhibit aggregation when incubated with these inhibitors. This suggests that megaislet formation was an active process requiring protein-RNA synthesis rather than passive clumping or aggregation that can accompany metabolically altered or dying islets undergoing cellular shedding and adhesion. Immunohistochemical localization demonstrated that insulin, glucagon, somatostatin, and pancreatic polypeptide-immunoreactive cell types were present within the islets derived from this technique. The cellular topography of these islets was not unlike that described by others for islets cultured from enzymatic isolation. This culture model may serve as a resource for mature, viable islets isolated without mechanical or enzymatic disaggregation which can have attenuating effects on islet function.

Animals↗
PubMed1986

An immunohistochemical, ultrastructural, and physiologic study of pancreatic islets from copper-deficient, penicillamine-treated rats.

Murine copper deficiency induced by diet and supplemented with a copper chelator is known to produce a progressive atrophy of pancreatic acinar tissue largely replaced by noninflammatory lipomatosis, while the ductal and endocrine systems appear to remain unaffected. The islets were studied morphologically and physiologically in animals rendered copper deficient by diet and supplemented with D-penicillamine. Using immunohistochemistry, the distribution of islet cell types from copper-deficient animals exhibited a normal cellular complement for A-, B-, D-, and PP-cells. Ultrastructural analysis showed the islet tissue remains normal in appearance during the course of the metal-deficient state. Physiologic data based on the response of islets to a low- and high-glucose load in perfused, isolated pancreata as well as intravenous glucose tolerance tests indicated that insulin-secreting B-cells were functionally normal. Because of the accessibility of islets enhanced by atrophy of acini, this model may be adopted for the isolation of viable islets and for in situ physiologic studies of islet hormone secretion.

Animals↗
PubMed1986

Vaso-occlusive crisis episodes in sickle cell disease.

Seventeen adult males and females with Hb-SS, Hb-SC (1) and Hb-S Thal (1) hemoglobinopathies were continuously studied for 3 years. Various hematological and biochemical parameters were measured in the venous blood of the subjects for blood gases, CBC profile, blood chemistry (SMA-18), fibrinogen, alpha-HBD and myoglobin levels, percent sickling, blood viscosity, oxygen affinity of whole blood, osmofragility of red blood cells and calcium and zinc contents in plasma and in RBC. The results were compared between those subjects who encountered more frequent vaso-occlusive crisis episodes (frequent sicklers) and those with fewer crisis episodes (infrequent sicklers), along with parameters between crisis and non-crisis states of frequent sicklers. Our studies showed that percent sickling, P50 for O2, CBC profile, PO2, serum calcium, ALP, LDH, alpha-HBD level, zinc and calcium levels in plasma and in RBC varied between crisis and non-crisis states of frequent sicklers and also between frequent sicklers and infrequent sicklers. A logical explanation of such variations may help in understanding the etiology of vaso-occlusive crisis episodes in sickle cell disease.

Adult↗
PubMed1982

Two-point tactual discrimination on the back: a signal-detection approach.

This investigation determined if subthreshold two-point aesthesiometer separations could be discriminated from one-point on the back, using a fixed-based matching signal detection technique. Subjects reliably discriminated two-point separations as small as 2 mm from one point on the back. In addition, the back appears to be more sensitive to discriminating two points from one point than the dorsal forearm.

Back↗
PubMed1981

Two-point tactual discrimination: a signal detection approach.

This investigation determined if subthreshold two-point aesthesiometer separations could be discriminated from one-point on the dorsal forearm. A fixed-based matching signal-detection technique was employed. The results indicated that subjects can reliably discriminate two-point separations as small as 2 mm when compared to one point.

Discrimination Learning↗
PubMed1980

Diagnostic dilemmas and cultural diversity in emergency rooms.

Language and cultural beliefs play an extremely important role in the interaction between patients from diverse cultural groups and physicians. Especially in emergency rooms, there are many dangers in missed communications. A patient from a foreign culture, especially one who does not speak English, often expresses symptoms in ways that are unfamiliar to many American physicians. Specific areas of cultural vulnerability can be identified for the major ethnic groups in the United States as they interact with the scientific medical system. A short review of folk medical beliefs and recommendations for improving diagnostic accuracy and treatment may assist emergency room staffs in offering care that is culturally acceptable to patients of diverse ethnic backgrounds.

Adult↗
PubMed1978

Frequency of occurrence of the transversus menti muscle.

The transversus menti muscle was present in 9 of 16 cadaver specimens. The anatomy and the frequency of this muscle are discussed, as is the possibility of its clinical use in the reconstruction of defects around the angle of the mouth in selected patients.

Aged↗
PubMed1972

Comparison of murine sarcoma viruses in nonproducer and S + L - -transformed cells.

The biologic properties of murine sarcoma viruses in nonproducer and S(+)L(-) cells were compared. Each virus was found to be genetically stable through at least two cycles of rescue and transmission to new cells. There was no evidence for production of a defective murine leukemia virus by S(+)L(-) cells. The results are most consistent with the hypothesis that the sarcoma genome in S(+)L(-) cells contains information for replication functions which the virus in nonproducer cells either lacks or does not express.

Animals↗
PubMedDate not supplied

Angioarchitecture of the atrophic pancreas.

The pancreas has a complex vasculature which comprises both exocrine and endocrine structures. Copper deficiency induces highly selective acinar cell degeneration and progressive noninflammatory lipomatosis in pancreas while Langerhans islets, ducts, and nerves remain unaffected. Pancreatic vasculature was examined in rats that had dietary copper deficiency to characterize changes in the angioarchitecture of the gland. This model was used to assess the degree to which the vasculature of non-acinar components of the gland are potentially altered under conditions of exocrine atrophy. Ultrastructure of pancreas was examined by histology, enzyme histochemistry and immunohistochemistry, corrosion casting and scanning electron microscopy, in situ vascular staining, microsphere injection, biochemical analysis, and morphometry in copper-deficient rats. Results show that no acute angiopathic changes indicative of vascular disorganization accompany atrophy. Only a reduction in the complexity of the capillary beds, which normally vascularize the dense acinar parenchyma, was found. Microsphere quantitation also showed that blood flow to the lipomatous gland remains intact. Furthermore, analysis of the angioarchitecture of the atrophied pancreas supports a largely autonomous blood supply to islets and ducts. These observations support the hypothesis that while the vasculature of the atrophied gland is modified in vascular regions severely targeted by acinar necrosis, the overall structural features of the angioarchitecture are preserved. The atrophied gland thus provides an experimental model to study the vascular routes supplying islet and ductal blood flow within the complex pancreatic circulation.

Animals↗