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Biomedical subjects

J L Cunningham

Publications and source records attributed to J L Cunningham.

68 records · Page 4Linked to original sources
PubMed1974

Acetanilide oxidation in phenylbutazone-associated hypoplastic anaemia.

Acetanilide like phenylbutazone is paraoxidized by the liver endoplasmic reticulum as a primary biotransformation step. Both compounds were given at different times to each of 10 healthy volunteer subjects and the plasma disappearances measured. Correlation was shown between plasma clearance values of the two compounds (r = + 0.7067; P < 0.05).Eight patients with hypoplastic anaemia after phenylbutazone therapy were investigated. Plasma clearance values and half lives of acetanilide were measured in this group of patients and compared with those of a group of 30 healthy volunteer controls. There was a significant decrease in clearance (P < 0.01) and lengthening of half lives (P < 0.001 in the patients with phenylbutazone-associated hypoplasia. Five patients with idiopathic aplastic anaemia-that is, without history of antecedent phenylbutazone ingestion-were similarly investigated with acetanilide and there was no significant difference between the results in these patients and those in the control group.It is suggested that relatively poor paraoxidation of phenylbutazone producing high blood concentrations on a given dose may be a factor responsible for the drug-associated hypoplasia even though it does not explain the similar pattern of adverse reactions reported in association with oral administration of the metabolite oxyphenbutazone.

Acetanilides↗
PubMedDate not supplied

Disposition kinetics of disopyramide in patients with renal insufficiency.

The pharmacokinetics of an intravenous injection of disopyramide was studied in five normal subjects and six patients with varying degrees of renal impairment. The elimination rate constant (beta) was related to the endogenous creatinine clearance (Clcr). However, a decrease in beta was not observed until the Clcr was reduced below 40 ml min-1. Below 40 ml min-1 a linear relationship existed between beta and Clcr. Similarly, the plasma elimination half-life (t 1/2 beta) showed a significant increase when the Clcr was less than 30 ml min-1. Hence, dosage modification for disopyramide is necessary only when renal function is severely impaired. Overall, the apparent volume of distribution in patients with renal insufficiency was reduced to two-thirds of that in normal subjects. Therefore, in patients with Clcr less than 40 ml min-1 both the loading and maintenance dose of disopyramide should be reduced.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Bone loss during long term space flight is prevented by the application of a short term impulsive mechanical stimulus

In long term space flight, the mechanical forces applied to the skeleton are substantially reduced and are altered in character. This reduced skeletal loading results in a reduction in bone mass. Exercise techniques currently used in space can maintain muscle mass but the mechanical stimulus provided by this exercise does not prevent bone loss. By applying an external impulsive load for a short period each day, which is intended to mimic the heel strike transient, to the lower limb of an astronaut during a long term space flight (5 months), this study tests the hypothesis that the bone cells can be activated by an appropriate external mechanical stimulus to maintain bone mass throughout prolonged periods of weightlessness. A mechanical loading device was developed to produce a loading of the os-calcis similar to that observed during the heel strike transient. The device is activated by the astronaut to provide a transient load to the heel of one leg whilst providing an equivalent exercising load to the other leg. During the EUROMIR95 mission on the MIR space station, an astronaut used this device for a short period daily throughout the duration of the mission. Pre- and post-flight measurements of bone mineral density (BMD) of the os-calcis and femoral neck of the astronaut were made to determine the efficacy of the device in preventing loss of bone mineral during the mission. On the os-calcis which received the mechanical stimulus, BMD was maintained throughout the period of the flight, while it was reduced by up to 7% on the os-calcis which received no stimulus. Post-flight, BMD in both the stimulated and non-stimulated os-calcis reduces, the extent of this reduction however is less in the stimulated os-calcis. For the femoral neck, the mechanical stimulation does not produce a positive effect.

Aerospace Medicine↗
PubMedDate not supplied

Adolescent anger: a developmental study.

This research examined adolescent anger in a cohort of adolescents measured twice, once during the freshman year and again in the senior year of high school. Anger was measured by the Anger Index, a questionnaire developed by Siegel (1984). The purpose of the research was to determine if adolescent anger changed over time and if there were gender differences. Results of the study indicated that anger scores appeared to be stable over time for both boys and girls. There were gender and time differences on individual responses for several items, indicating that certain dimensions of anger may differ over time and by gender. It also appeared possible that the interpretation of certain questions on the anger index was different for the adolescents at the two time intervals.

Adolescent↗
PubMedDate not supplied

The effects of urine pH and plasma protein binding on the renal clearance of disopyramide.

To ascertain whether the renal clearance of disopyramide (pKa = 8.36) is affected by urine pH, the disposition kinetics of disopyramide were compared during excretion of acidic and alkaline urine following both single dose intravenous (2mg/kg) and oral (5 mg/kg) administration to 4 healthy male volunteers. No significant difference was observed in the plasma concentration-time curve of disopyramide. The mean 72 hour recovery of disopyramide and its N-deisopropyl metabolite (MND) in urine was 55.1 and 20.3% of the dose respectively, with no apparent difference between the two routes of administration or pH of urine. Renal clearance of disopyramide was found to vary with time, which is partly the result of a concentration dependent change in plasma protein binding. The unbound fraction of drug in plasma varied from 0.32 to 0.72 between 0.4 to 4microgram/ml concentration. However, time-dependent change in renal clearance of disopyramide persists even after correction for plasma protein binding.

Administration, Oral↗
PubMedDate not supplied

Biomechanical measurement of fracture healing.

Three techniques for measuring fracture healing are presented. These techniques are: (1) use of strain gauge measurements of the forces in an external fixator to determine fracture stiffness, (2) measurement of the vibration modes of a fractured long bone compared to the unfractured contralateral and (3) comparison of the ultrasound velocity across the fracture site with that for the normal unfractured bone. Examples of clinical results obtained using these techniques are presented, and the advantages and disadvantages of each technique are discussed.

Biomechanical Phenomena↗
PubMedDate not supplied

Bond strength variation of synthetic resin teeth in dentures.

The bond strength of denture teeth to acrylic resin denture bases was determined by producing tensile test specimens from standardised and anonymously presented partial dentures. Ten dentures were produced by randomly selected commercial dental laboratories and five were produced in a university dental laboratory. The tooth debonding forces exhibited a wide range of variation both within and between dentures. The university-produced dentures showed, on average, a slightly improved tooth bond strength. This study highlights the need for further investigation of this problem and for the development of a standardised technique to provide satisfactory denture tooth bonding.

Acrylic Resins↗