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Biomedical subjects

R G Chapman

Publications and source records attributed to R G Chapman.

At least 19 recordsLinked to original sources
PubMed2001

Basicity of the amino groups of the aminoglycoside amikacin using capillary electrophoresis and coupled CE-MS-MS techniques.

This paper describes the use of capillary electrophoresis (CE), and coupled CE and mass spectrometric techniques, to measure the values of the pKa of the amino groups of the aminoglycoside antibiotic amikacin and of its acetylated derivatives. These values of pKa (8.4, 6.7, 9.7, 8.4) were determined by measuring the electrophoretic mobilities of the molecules as a function of pH; they are within 0.7 unit of certain values reported in the literature (by 13C and 15N NMR spectroscopies) but resolved ambiguities left by these earlier studies. The range of values of pKa of amino groups also indicates the complex dependence of the acidity of a functional group (and thus the extent of ionization at a specified value of pH) on the molecular environment of that group.

Acetylation↗
PubMed2000

Restricted motion of guests confined in carceplexes and capsules.

Guest orientation within carceplexes and capsules was determined qualitatively from NMR data, and the molecular mobility of guests was determined via coalescence of (1)H NMR signals. Both are highly dependent on guest size and shape, as is interconversion of twistomers. Incarceration of 1,4-thioxane results in a large (1.8 kcal/mol) constraint on thioxane's conformational mobility (chair-to-chair interconversion). Similar conformational constraints (1.6 kcal/mol) were determined for 1,4-dioxane both when incarcerated in carceplex 1b and when encapsulated reversibly in capsule 3b. Encapsulation-induced conformational constraints of this magnitude are unprecedented, and are particularly striking for the noncovalently linked capsules.

Magnetic Resonance Spectroscopy↗
PubMed1988

Nursing procedures and their function as policies for effective practice.

Documents covering nursing procedures form part of the District Health Authorities policies in the United Kingdom. How far such written documents contribute to standards of care has not been established. As part of a wider investigation, a postal survey of all District Health Authorities in England and Wales was undertaken to examine the content of procedures for catheter care. Eighty-two per cent of Authorities responded and it was found that the documents consisted largely of a detailed list of steps to be followed. There was no complete coverage of all components of care and there were gaps in information concerned with patient safety. In discussion it is suggested that procedures reflect technical performance rather than guidelines for good practice. In the light of this analysis it is argued that the profession should reconsider the place of such documents within the Health Authorities' quality assurance programme.

Catheters, Indwelling↗
PubMed1988

Bacteriuria during indwelling urethral catheterization.

The incidence of bacteriuria and the risk factors related to its acquisition were determined in a prospective study of 220 hospitalized patients. Bacteriuria was recorded in 97/220 (44%) of patients, in 42 cases within 48 h (Group A) and in 55 cases more than 48 h (Group B) after catheterization. The results of a multivariate analysis of Group A demonstrated that the reason for catheterization, the use of antimicrobial chemotherapy and the medical specialty of care were the only variables of those assessed associated with the acquisition of bacteriuria. In a similar analysis of Group B the number of days the catheter was in situ and the use of antimicrobial chemotherapy were the only factors which achieved statistical significance.

Adolescent↗
PubMed1986

The candidate's view of the orthopaedic residency selection process.

Two hundred and seventy-nine applicants for an orthopaedic residency who participated in the 1985 match program returned a questionnaire that was designed to evaluate the candidate's impression of the process of selecting a residency. The respondents requested information from an average of thirty-three programs and applied to an average of twenty-two programs. The candidates who participated in the match each ranked an average of 7.5 orthopaedic residency programs. The candidates assigned a high ranking to programs in which the morale of the staff was high and the faculty was committed to teaching. Low morale, poor treatment by people at the institution, an inadequate commitment to teaching, a disorganized day of interviews, and a program in transition were the major reasons for not ranking a program. We concluded that the process is run for the convenience of the programs, with little regard to the problems that are faced by the applicants.

Choice Behavior↗
PubMed1985

Patient preferences in surgery for scoliosis.

To assess individual preferences for a method of scoliosis surgery, we surveyed 224 teen-age patients, their parents, orthopaedic surgeons, and other health professionals. Rather than asking the respondents directly for the relative importance that they would assign to the four possible outcomes, we employed conjoint analysis, a preference measurement technique that is widely used in marketing and psychology. In conjoint analysis, respondents explicitly trade off the relative desirability of certain aspects of the outcome of scoliosis surgery--for example, between greater degree of curve correction or greater risk of reoperation. This study indicated that risk of nerve damage had the highest relative importance to the respondents, followed by risk of reoperation, curve correction, and aftercare, in that order. This ranking was found in all five groups of respondents.

Adolescent↗
PubMed1979

Controlled comparison of cimetidine and carbenoxolone sodium in gastric ulcer.

Fifty-four outpatients with endoscopically diagnosed benign gastric ulcer were allocated at random to treatment with either cimetidine 800 mg daily for six weeks or carbenoxolone sodium 300 mg daily for one week then 150 mg daily for five weeks. Ulcers were reassessed by endoscopy at the end of the trial. The endoscopist was unaware of the treatment and did not take part in the clinical care of the patients. Twenty-one of the 27 patients (78%) given cimetidine and 14 of the 27 (52%) given carbenoxolone had healed ulcers. Symptomatic response occurred earlier with cimetidine but was not significantly better. Unwanted effects were more common in the carbenoxolone group: 12 patients developed hypokalaemia, four of whom needed oral potassium supplements. The results suggest that histamine H2-receptor blockade is at least as effective as carbenoxolone sodium for benign gastric ulcer and produces fewer side effects.

Administration, Oral↗
PubMed1978

Linkage and gene localization of hereditary spherocytosis (HS).

Fifteen kindreds with dominant hereditary spherocytosis (HS) were studied. Expansion of the data from a family with an 8/12 translocation provided further evidence that at least one locus for HS is located near the breakpoint of the translocation. Linkage analysis of all families showed a lack of linkage with all marker loci studied except for Gm (IgG). Linkage between Gm and HS was shown to be significant with a maximum lod score of 3.42 at a recombination fraction of 22%. No heterogeneity of the recombination fraction was observed either between sexes or between families. These results are compatible with the hypothesis that HS is not a heterogeneous disorder.

Female↗
PubMed1977

Levels of erythropoietin in patients with the anemias of chronic diseases and liver failure.

Two mechanisms are felt to be responsible for the production of anemia in patients with chronic diseases. The first is failure to produce adequate amounts of erythropoietin (EP), and the second is failure to deliver iron to the bone marrow in amounts sufficient to support normal erythropoiesis. In order to evaluate these hypotheses we studied urine and serum EP levels and levels of 2,3-diphosphoglycerate in normal subjects, in patients with the anemia of chronic diseases, in patients with chronic liver disease, and in patients with a variety of other anemias. Based on the results, we propose first that insufficient production of EP is one of the major mechanisms responsible for anemia in patients with chronic diseases. Second, insufficient production of EP is, in part, responsible for anemia seen in patients with chronic liver disease. Third, serum and urine EP levels decrease with aging, and this correlates with the fall of hemoglobin levels seen in older normal subjects.

Aging↗
PubMed1968

Red cell life span after splenectomy in hereditary spherocytosis.

Despite the persistence of spherocytosis after splenectomy in hereditary spherocytosis, it has usually been assumed that red cell life span returns completely to normal after this treatment. Diisopropyl fluorophosphate. DF(32)P, a noneluting red cell label, was given intravenously to 11 patients in five unrelated families 2-27 yr after splenectomy for typical hereditary spherocytosis. Hemoglobin ranged from 14.0 to 19.8 g/100 ml in this group and reticulocytes from 1.1 to 2.9%, showing the excellent clinical response to splenectomy. Loss of red cell radioactivity corrected for radiophosphorus decay was linear with time during the 60-70 days of the study. Red cell survival as indicated by this rate of loss was 96 +/- 13 days (range 76-118 days), significantly less than the 123 +/- 14 days observed with the same method in 12 persons with normal red cells (P < 0.0005). I conclude that splenectomy does not eliminate the decreased red cell survival in hereditary spherocytosis. The residual 22% decrease in red cell survival is clinically unimportant, but it must be considered in evaluation of biochemical differences observed in hereditary spherocytic red cells.

Adult↗