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Biomedical subjects

M Holloway

Publications and source records attributed to M Holloway.

53 records · Page 3Linked to original sources
PubMed1990

Pharmacokinetics of calcitriol in continuous ambulatory and cycling peritoneal dialysis patients.

Oral calcitriol is commonly used for the treatment of secondary hyperparathyroidism in patients undergoing long-term dialysis, but it has been suggested that intravenous (IV) or intraperitoneal (IP) administration enhances the therapeutic efficacy of the sterol. To examine potential mechanisms for this difference, the bioavailability of calcitriol was evaluated after single oral (PO), IV, and IP doses of 60 ng/kg in each of six adolescent patients with osteitis fibrosa undergoing continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD). Serum calcitriol levels were 3.6 +/- 4.3, 8.2 +/- 7.5, and 2.5 +/- 3.0 pg/mL, respectively, before IV, PO, and IP doses of the sterol; these values increased to similar levels at 24 hours: 55.6 +/- 14.6 pg/mL after PO, 56.4 +/- 17.6 pg/mL after IV, and 53.8 +/- 20.1 pg/mL after IP. Serum calcitriol levels were higher 1, 3, and 6 hours after IV injections than after PO or IP doses; values thereafter did not differ among groups. The bioavailability of calcitriol, determined from the 24-hour area under the curve (AUC0-24) for the increase in serum calcitriol concentration above baseline values was 50% to 60% greater after IV, 2,340 +/- 523 pg.mL-1.h-1, than after PO, 1,442 +/- 467 pg.mL-1.h-1, or IP, 1,562 +/- 477 pg.mL-1.h1, dosages, P less than 0.05. These differences were due to higher values for AUC during the first 6 hours after calcitriol administration. Although IP calcitriol did not increase sterol bioavailability, radioisotope tracer studies indicated that 35% to 40% of the hormone adheres to plastic components of the peritoneal dialysate delivery system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Peroxisomes in pigment epithelium and Müller cells of amphibian retina possess D-amino acid oxidase as well as catalase.

In this paper we identify peroxisomes in Müller cells and retinal pigment epithelial cells of Rana pipiens and Xenopus laevis by virtue of their content of cytochemically stainable catalase. These organelles have the form of an extensive, branched system of tubules in the retinal pigment epithelium and appear as discrete ovoid structures in the Müller cells. In both the pigment epithelium and the Müller cells a second peroxisomal enzyme, D-amino acid oxidase, can be detected in the same structures as catalase by means of a cerium-based cytochemical staining procedure. This oxidase is active only against nonpolar and polar, uncharged D-amino acids.

Animals↗
PubMed1988

Induction of sister-chromatid exchanges by d(42 MeV)-Be neutrons in unstimulated human-blood lymphocytes.

The ability of d(42 Mev)-Be neutrons and 250 kV X rays to produce sister-chromatid exchanges (SCE) has been re-examined using unstimulated (G0) human-blood lymphocytes. Contrary to a previous report, the neutrons produced a significant and dose-dependent increase in SCE. X rays, as previously, produced no measurable increase at any absorbed dose. The relative biological effectiveness (RBE) for this end-point is therefore undefined and effectively infinite. In contrast to the findings of many workers, the between-cell distributions of SCE were, in most cases, underdispersed. This could imply that the SCE burden of a cell was not selectively neutral in these experiments.

Dose-Response Relationship, Radiation↗
PubMed1985

Genetic and quantum chemical basis of the mutagenicity of nitroarenes for adenine-thymine base pairs.

The mutagenicity of nitroarenes for Salmonella typhimurium strains with adenine-thymine base pairs at the mutational site is dependent upon enzymic reduction of the nitro function. Although the electrophilic metabolites of nitroarenes are capable of mutating adenine-thymine base pairs, they show a marked preference for guanine-cytosine pairs when given a choice. Quantum chemical calculations indicate the reactivity order for nucleophilic sites in an AT run of base pairs to be the N-7 of adenine (N7(A)) first, followed by an approximately equal reactivity for C-8 of adenine (C8(A)) and O4 of thymine (O4(T)). Given the low probability of reaction of electrophilic metabolites of nitroarenes with adenine-thymine base pairs, the mutagenic potency of nitroarenes for strains with adenine-thymine base pairs at the mutational site is remarkable.

Adenine↗
PubMed1984

Relationship between polarographic reduction potential and mutagenicity of nitroarenes.

A series of nitropyrenes and other nitroarenes were reduced electrochemically with a dropping mercury electrode. The half-wave potentials (E1/2) corresponding to the reduction of the various nitro functions mutagenicities exhibited by these chemicals in Salmonella typhimurium strains TA98 and TA1538 was demonstrated. A linear relationship between E1/2 and the calculated energies of the Lowest Unoccupied Molecular Orbital (LUMO) was also established. This indicates that the mutagenicities of nitroarenes can be predicted from calculated LUMO energies.

Fluorenes↗
PubMed1975

Complications of silicone implant surgery in the metacarpophalangeal joint.

Of 162 metacarpophalangeal silicone prostheses inserted from 1967 to 1973, fifteen fractured, two were associated with an infection, and there was one case of skin necrosis. A recurrence of ulnar drift occurred in four hands. Three prostheses had to be removed and in one such case additional significant foreign-body reaction was evident. Although the complication rate was over 10 per cent, the failure rate was fairly low.

Arthroplasty↗
PubMedDate not supplied

Patient concerns after discharge from rehabilitation.

A major nursing role in rehabilitation is patient teaching. Through education, the patient is armed with knowledge that enables him or her to reenter community life prepared to be as independent as possible. The teaching in a rehabilitation facility should be evaluated continually to assure its ability to meet patients' needs. This article describes a study in which phone calls made by patients after their discharge were assessed to determine whether knowledge deficits had prompted the calls. The results were used by the hospital nursing staff to make changes in their patient teaching.

Aftercare↗
PubMedDate not supplied

A&E management of sexual assault.

The care of women who have been raped or sexually assaulted tends to be poorly managed in accident and emergency departments. In 1991, a special suite was established at Hillingdon Hospital for the care of such women. This article discusses the process of setting up the unit and looks at what has been achieved so far.

Education, Nursing, Continuing↗
PubMedDate not supplied

Pediatric peritoneal dialysis training: characteristics and impact on peritonitis rates.

OBJECTIVE: Peritonitis is the leading cause of technique failure in pediatric patients on peritoneal dialysis. A survey was developed to determine what impact, if any, training practices and staffing patterns have on peritonitis rates in pediatric patients. DESIGN: A survey developed by the International Society for Peritoneal Dialysis Advisory Committee on Peritonitis Management in Pediatric Patients. PATIENTS: The survey was distributed to 168 centers and was completed by 76 (45%) centers. A total of 597 children younger than 21 years of age received peritoneal dialysis in these centers. RESULTS: The peritonitis rate was significantly lower (1 episode/19.9 months vs 1 episode/13.5 months; p < 0.05) in programs characterized by larger patient numbers (> or = 15 patients vs < 15 patients) and longer training time dedicated to theory and practical/technical skills (p < 0.01). CONCLUSION: Peritoneal dialysis training is an important factor that influences the rate of peritonitis. The results of this survey reinforce the value of the time committed to this effort.

Canada↗