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Biomedical subjects

M Crowe

Publications and source records attributed to M Crowe.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of anions on the binding of the cAMP receptor protein to the lactose promoter.

The DNA binding affinities of several gene-regulatory proteins, restriction endonucleases and the Escherichia coli RNA polymerase have previously been found to be dependent on the nature of the dominant buffer anion. To discover whether the E. coli cAMP receptor protein (CAP) exhibits a similar dependency, we measured its affinity for its primary lactose promoter binding site (lac site 1) in buffers in which the principal anion was chloride, phosphate, sulfate, acetate, or glutamate. We found that the affinity of CAP for lac site 1 is affected only slightly by changes in the dominant buffer anion. The binding of cAMP is similarly insensitive to buffer anion type, indicating that specific protein-anion interactions, if they occur, must be similar for the free and cAMP-bound forms of the protein. The effect of anion substitution on the ability of acrylamide to quench the intrinsic fluorescence of tryptophanyl residues of CAP is also small, suggesting that changes in buffer anion composition have minimal effect on the conformation of tryptophan-proximal regions of CAP. This conclusion is extended by the finding that anion substitution has a relatively small effect on the urea-concentration dependence of CAP denaturation. Taken together, these results support the notion that neither CAP nor CAP.cAMP nor the CAP.cAMP complex with lac promoter DNA interact selectively with anions present in the surrounding buffer. A possible role for this anion-insensitivity in the in vivo function of CAP is suggested.

Anions↗
PubMed1992

Oral estrogen retains potency as an aversion agent in eggs: implications to studies of community ecology and wildlife management.

The first of two experiments with laboratory rats demonstrated that oral estrogen (17 alpha-ethinylestradiol) can remain in the albumen of eggs at room temperature for up to 8 days with undiminished capacity to produce conditioned taste aversion. The second experiment showed that estrogen remains potent in the yolk of eggs for at least 4 days. There is now greater assurance that egg prey placed into the field will induce reliable CTA among mammalian predators. Community ecologists interested in such processes as competitive release and the responses of prey populations to reduced predation upon their eggs can selectively factor predation out of field experiments without the need for physically excluding predators. Wildlife biologists interested in reducing predation upon the eggs of endangered species now have greater assurance that estrogen-treated egg baits will suppress predation in a more cost-effective manner and with less likelihood of discrimination between treated eggs and those of endangered species.

Animals↗
PubMed1990

Outcome of stroke related admissions to a general hospital.

In a prospective study of patients admitted to a general hospital, 43 patients with stroke were identified accounting for 3.9% of all medical admissions over a six month period. Of these, 23.2% died in hospital, whilst 46.5% were discharged to the community, and 30.3% to institutional care after a mean length of stay in hospital of 24.5 and 34 days respectively. At follow-up seven months following discharge, most patients were alive and still residing in the community or institution to which they had been discharged. The majority of survivors (57%) however, were severely handicapped, 37% of whom were resident with carers in the community. Our study emphasises the overly long stay of stroke patients in the acute hospital, and the high morbidity in survivors with consequent demand on institutional and community care services.

Aged↗
PubMed1985

The size and strength of the quadriceps muscles of old and young men.

The mean isometric strength of the stronger quadriceps muscles of 12 healthy men in their seventies was 39% less than that of 12 healthy men in their twenties (P less than 0.001). The cross-sectional area of the quadriceps was measured at mid-thigh, by ultrasound scanning; the older men's stronger quadriceps were 25% smaller (P less than 0.001). The ratio of the stronger quadriceps' strength to its cross-sectional area was very similar in the old men to values obtained previously for both old and young women, but averaged 19% less than in the young men (P less than 0.02). Quadriceps size and strength were correlated in the old men (r = 0.77, P = 0.03) but not in the young men (r = 0.15). The principal axis of the relationship between quadriceps size and strength in the old men was very similar to those previously reported for both old and young women. The quadriceps strength of some young men is greater than would be expected from the size of the muscle.

Adult↗
PubMed1984

Size and strength of the quadriceps muscles of old and young women.

Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n = 25) and in their 20s (n = 25) and have compared it with the mid-thigh cross-sectional area of the same muscles. The two groups of women showed similar variability when strength was measured on consecutive days (coefficients of variation: 8%). The older women were 35% weaker than the young women (P less than 0.001) and their quadriceps cross-sectional area was 33% less (P less than 0.001). Quadriceps strength and cross-sectional area were correlated (r = 0.66, P less than 0.001, elderly; r = 0.53, P less than 0.01, young) and the principal axis of the relationship was closely similar for the two groups of women. There is therefore no difference in the intrinsic strength of the quadriceps muscles of healthy women in their third and eighth decades. This report also provides normative data for the objective evaluation of quadriceps weakness and/or wasting in female patients. The techniques involved are straightforward, the dynamometer is easily made, and compound ultrasound imaging is widely available.

Adult↗
PubMed1984

Examination of the energetics of aging skeletal muscle using nuclear magnetic resonance.

Human skeletal muscle has been studied in vivo by 31P nuclear magnetic resonance. Young adult subjects were compared with healthy elderly subjects aged 70-80 years. Intracellular pH and concentrations of adenosine triphosphate (ATP), phosphocreatine and inorganic phosphate were measured. At rest, no differences were found between the two age groups. Aerobic dynamic exercise resulted in a similar reduction of phosphocreatine in both groups while the ATP concentration did not change. The pH fall in exercise was not significantly different in the elderly and younger subjects. The time to resynthesize ATP in the recovery period as measured by the time to replete phosphocreatine was also not different in the two groups. The results suggest that the aging process does not affect the metabolic ability of human skeletal muscle to respond to exercise and that changes found in muscle of the elderly are not due to alterations in energy production.

Adenosine Triphosphate↗
PubMed1981

Myocardial glycolytic and gluconeogenic enzyme activity during cardiopulmonary bypass in humans.

Through a study of the activity of the regulatory enzyme of glycolysis phosphofructokinase and the regulatory enzyme of gluconeogenesis fructose-1,6-diphosphatase, myocardial metabolism has been evaluated in the human heart during cardiopulmonary bypass. Three ventricular transmural biopsy specimens were obtained at open-heart surgery before cardiopulmonary bypass was instituted and three similar specimens were taken 30 minutes after cardiopulmonary bypass was started. The enzyme assays were performed on the supernatant obtained from myocardial cells disrupted by sonication. The activity of both enzymes increased during the anoxic conditions of cardiopulmonary arrest. The increase in phosphofructokinase activity is likely due to an overall increase in glycolytic activity, but the presence and increased activity of fructose-1,6-diphosphatase was unexpected.

Cardiopulmonary Bypass↗
PubMed1977

The significance of free blood in liquid and solid tumours.

Impregnation of the vasculature with ink was used to study microvascular changes induced in rats by liquid (ascites) and solid growth of W256 and Y-P388 tumour cells. Ascites fluid produced by both tumours was heavily blood-stained; the deep red colour of solid tumour deposits was similarly due to the presence of free blood. In both types of tumour growth this free blood was due to diapedesis of erythrocytes through tips of capillary sprouts which grow when neovascularization (angiogenesis) occurs in response to any suitable (non-neoplastic or neoplastic) stimulus. Ascites growth of these tumours induced profuse sprouting from the peritoneal capillaries; this sprouting, together with the "bleeding" it caused, were inhibited by local pre-irradiation of the peritoneal vasculature with X-rays before intraperitoneal inoculation of rats with the tumours. Similar angiogenesis with bleeding did not occur following inoculation with an allogeneic tumour in rats which had been previously immunized against the tumour. LI tumour cells (tumour cells lethally irradiated in vitro to destroy their proliferative integrity, but which remain metabolically active) also induced sprouts to grow in close proximity to the implanted LI cells, but heat-killed tumour cells caused no sprouting. The nature and significance of neovascularization of tumours and their so-called "haemorrhagic" growth are discussed.

Angiogenesis Inducing Agents↗
PubMedDate not supplied

Sex therapy: the successes, the failures, the future.

Sexual dissatisfaction or dysfunction occurs in one fifth to one third of the adult population. Although great advances have been made in the pharmacological treatment of impotence, psychological and relationship therapy remain the mainstay of the treatment of sexual problems within relationships.

Combined Modality Therapy↗
PubMedDate not supplied

The i.v. nurse and the i.v. drug abuser: medical and psychosocial implications.

When I.V. nurses treat I.V. drug abusers, they must be aware of the medical and psychosocial issues relevant to this group. Medical issues include the I.V. drug abuser's depleted venous access and this group's high rate of infection with HIV and other blood pathogens. Psychosocial issues relate to the various social and psychological problems associated with drug abuse. Further, when caring for these patients who are at high risk for HIV and other serious blood infections, the I.V. nurse may experience a conflict between her desire to care for the patient and her fear of contracting HIV or another infection through patient contact. Education is recommended so that I.V. nurses can reduce their risk of infection with blood-borne diseases and can better understand these patients. Also suggested are a multidisciplinary approach to treatment and referral to drug rehabilitation programs.

Acquired Immunodeficiency Syndrome↗