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Biomedical subjects

M F Wright

Publications and source records attributed to M F Wright.

13 recordsLinked to original sources
PubMed2001

Prostaglandin F(2alpha) regulation of the bovine corpus luteum endothelin system during the early and midluteal phase.

Recent evidence in the cow suggests that endothelin-1 (ET-1) plays a role during prostaglandin (PG) F(2alpha)-induced luteal regression. We have examined the effects of treatment with PGF(2alpha) during the early and midluteal phases on three components of the endothelin system: endothelin-converting enzyme-1 (ECE-1), ET type A receptor (ET(A)), and ET-1 in the bovine corpus luteum (CL). Cyclic beef cows were injected (0 h) on Day 4 or 10 with either saline or the PGF(2alpha) analogue Lutalyse (15 mg). The CL were collected at 2 (n = 11), 10 (n = 23), 24 (n = 15), or 48 h (n = 12) after treatment. The cows in which CL were removed after 10 h comprised of two experimental groups. The first group (n = 11) received one injection; the second group (n = 12) received two injections, one at 0 h and one at 8 h. The cows in which CL were collected after 24 and 48 h received one injection every 8 h. Semiquantitative reverse transcriptase-polymerase chain reaction was used to evaluate the mRNA encoding ECE-1, ET(A), and ET-1. The ECE-1 and ET(A) proteins were evaluated by semiquantitative Western blot analysis. The ET-1 was the most likely component of the endothelin system target for PGF(2alpha) regulation during the midluteal phase. The ET(A) and ECE-1 genes were constitutively expressed in the Day 4 and Day 10 CL. A practical application of this observation is that it may be possible to target the ET-1 gene as a way to manipulate the luteolytic action of PGF(2alpha).

Actins↗
PubMed1998

Long-term care for elderly individuals and methods of financing.

As people age, there is an increase in chronic illness and disability and thus a growing need for long-term care. Unfortunately, the concept of long-term care can be very complex and confusing. Elderly individuals and their family members frequently have many questions, such as the following: What is long-term care, and who needs it? What long-term care services are available? Who will provide the services? Where will the services be provided? How much will the services cost, and who will pay for the expenses? Indeed, the cost of providing long-term care, whether in an institution or in one's own home, may represent an enormous burden for individuals and their families. Nurses, especially community health nurses, are in a prime position to address these questions and concerns to ensure appropriate care and services for their clients. This article addresses the questions clients frequently ask by defining long-term care and discussing long-term care services, settings, and providers. In addition, 4 methods of financing long-term care will be presented.

Aged↗
PubMed1996

Cranial desmoid tumor associated with homozygous inactivation of the adenomatous polyposis coli gene in a 2-year-old girl with familial adenomatous polyposis.

BACKGROUND: Familial adenomatous polyposis (FAP) is a dominantly inherited disorder characterized by the presence of more than 100 adenomatous polyps in the colon and rectum starting in the second decade of life. FAP is associated with extra colonic manifestations, including desmoid tumors. METHODS: A 2-year-old girl presented with a rapidly enlarging tumor of the forehead and a family history of FAP. The tumor was cultured for cytogenetic studies. A DNA linkage study using flanking and intragenic polymorphisms of the adenomatous polyposis coli (APC) gene was performed to identify the allele loss in the tumor. Germline mutation identification was by single strand conformation polymorphism analysis of exon 15 of the APC gene, with subsequent double stranded sequencing of fragments with conformational changes. A mutation-induced loss of a restriction site was used to confirm allele loss in the tumor. RESULTS: Microscopically, the tumor had desmoid features. Cytogenetic analysis of the tumor demonstrated loss of chromosome region 5(q21q22). A truncating adenomatous polyposis coli (APC) gene mutation was identified in the leukocyte DNA from the child and her affected father. Linked DNA markers suggested that the tumor had lost the maternal, wild-type allele. A mutation-induced restriction endonuclease site alteration demonstrated hemizygosity of the mutant sequence in the tumor DNA. CONCLUSIONS: These findings are compatible with the presence of a "second hit" inactivation of the APC gene and implicate this gene in the pathogenesis of desmoid tumors.

Adenomatous Polyposis Coli↗
PubMed1992

Cooling rate influences cryoprotectant distribution and organ dehydration in freezing wood frogs.

Ice formation in the freeze-tolerant wood frog (Rana sylvatica) induces the production and distribution of the cryoprotectant, glucose. Concomitantly, organs undergo a beneficial dehydration which likely inhibits mechanical injury during freezing. Together, these physiological responses promote freezing survival when frogs are frozen under slow cooling regimes. Rapid cooling, however, is lethal. We tested the hypothesis that the injurious effects of rapid cooling stem from an inadequate distribution of glucose to tissues and an insufficient removal of water from tissues during freezing. Accordingly, we compared glucose and water contents of five organs (liver, heart, skeletal muscle, eye, brain) from wood frogs cooled slowly or rapidly during freezing to -2.5 degrees C. Glucose concentrations in organs from slowly cooled frogs were significantly elevated over unfrozen controls, but no significant increases occurred in rapidly cooled frogs. Organs from slowly cooled frogs contained significantly less water than did those from controls, whereas water contents from rapidly cooled frogs generally were unchanged. Rapid cooling therefore inhibited the production and distribution of cryoprotectant and organ dehydration during freezing. This inhibition may result from an accelerated, premature failure of the cardiovascular system.

Adaptation, Physiological↗
PubMed1991

Effect of cooling rate on the survival of frozen wood frogs, Rana sylvatica.

Wood frogs (Rana sylvatica) were frozen to -2.5 degrees C under five distinct cooling regimes to investigate the effect of cooling rate on survival. Frogs survived freezing when cooled at -0.16 degrees C.h-1 or -0.18 degrees C.h-1, but mortality resulted at higher rates (-0.30 degrees C.h-1, -1.03 degrees C.h-1, and -1.17 degrees C.h-1). Surviving frogs in the latter groups required longer periods to recover, and transient injury to the neuromuscular system was evident. Some of the frogs that died had patches of discolored, apparently necrotic skin; vascular damage, as indicated by hematoma, also occurred. It is concluded that slow cooling may be critical to the freeze tolerance of wood frogs. Additional studies examined the effect of cooling rate on physiological responses promoting freeze tolerance. Mean glucose concentrations measured in plasma (15-16 mumol.ml-1) and liver (42-45 mumol.g-1) following a 2-h thaw did not differ between slowly- and rapidly-cooled frogs but in both groups were elevated relative to unfrozen controls. Thus, freezing injury to rapidly-cooled frogs apparently was not mitigated by the presence of elevated glucose. Water contents of liver tissue, measured 2 h post-thawing, did not differ between slowly-cooled (mean = 77.6%) and rapidly-cooled (mean = 78.5%) frogs. However, the mean hematocrit of slowly-cooled frogs (48%) was significantly higher than that (37%) of frogs cooled rapidly, possibly owing to differences in the dynamics of tissue water during freezing.

Animals↗
PubMed1991

Glucose loading prevents freezing injury in rapidly cooled wood frogs.

The wood frog (Rana sylvatica) is the most commonly studied of ten species of freeze-tolerant vertebrates. Under natural (i.e., slow) rates of cooling, freezing initiates the production of the cryoprotectant glucose, which is mobilized from the liver and distributed to tissues throughout the body. Rapid cooling during freezing is injurious to wood frogs, probably because cryoprotectant production and mobilization are inhibited. To test this hypothesis, we investigated whether rapid-cooling injury is reduced if exogenous glucose is experimentally introduced to tissues before freezing. Glucose-loaded and control (saline-injected) wood frogs were rapidly cooled during freezing to -2.5 degrees C and subsequently assayed for injury at both cellular (erythrocyte) and neuromuscular (behavioral reflex) levels. Rapid cooling produced substantial hemolysis in control frogs, but erythrocyte injury was significantly reduced in glucose-loaded frogs. Similarly neuromuscular injury was significantly higher in control frogs than in glucose-loaded frogs. These findings suggest that rapid-cooling injury results from an inadequate production and distribution of endogenous glucose during freezing. Furthermore, the inverse relationship between the degree of freezing injury and the quantity of exogenous glucose present strongly implicates glucose as a cryoprotectant in R. sylvatica.

Animals↗