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Biomedical subjects

R Hardy

Publications and source records attributed to R Hardy.

15 recordsLinked to original sources
PubMed1979

A computer program for life table regression analysis with time dependent covariates.

This paper presents a computer program for analyzing time-dependent covariables in survival studies by the life table regression model described by Holford [3]. Basically, life table regression incorporates the elements of regression and the life table into a single model. Regression parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides two methods for testing hypotheses concerning regression coefficients, namely the standard normal deviate test and a Wald statistic based on the first and second derivatives of the log likelihood. Residual plots are provided to assess the fit of the model to the data.

Actuarial Analysis↗
PubMed1979

Differentiation of fluorescent pseudomonads by their effect on milk agar.

Eighty-six clinical isolates of fluorescent pseudomonads that did not produce pyocyanin on Diagnostic Sensitivity Test Agar or Cetrimide Agar were identified on the basis of their antibiotic sensitivity, production of pigment on King's "A" medium, growth at 42 degrees C, production of lecithinase and hydrolysis of gelatin. The identity of the strains was confirmed in tests with the ammonium salt sugars ethanol, glucose and mannitol. These tests were adequate for distinguishing between the three important fluorescent pseudomonads. The detection of casein hydrolysis on milk agar was assessed as a rapid method of distinguishing P. aeruginosa from the other species of fluorescent pseudomonads but proved unhelpful when compared with, or included in, a small set of tests. Most strains of P. aeruginosa and P. fluorescens hydrolysed casein.

Agar↗
PubMed1978

Occurrence and fate of organic and inorganic contaminants in marine animals.

Most chemical contaminants occur in highest concentrations in coastal waters, often maximized in very localized areas. In general, this situation represents the exposure pattern for marine animals. However, the availability of contaminant to an organism depends not only on its concentration but also on its chemical nature, its physical state, and whether the source of exposure is the surrounding seawater or the diet. Depending on the type of exposure, uptake occurs across absorptive surfaces, such as those of the respiratory apparatus or gastrointestinal tract, where selectivity may occur, even among neighboring homologs. Deposition in tissues, accumulation, degradation, or depuration depends on tissue type, metabolic processes, detoxification mechanisms, and the adaptive status of a particular animal. This hypothesis is examined briefly for hydrocarbons, pesticides, other miscellaneous organic contaminants, heavy metals, and radionuclides. It is concluded that most data relate to occurrence and distribution. Considerably less information is available on the underlying biochemical processes.

Animals↗
PubMed1977

Use of transcutaneous electrical stimulation in the control of postoperative pain.

Perception and relief of pain were studied in a varied group of fifty patients who had undergone laparotomy with upper abdominal midline incisions. Twenty-six patients were supplied with functioning transcutaneous electrical stimulators. Twenty-four received nonfunctioning machines. The controls were randomized by a nurse not otherwise involved in this study. Only seventeen of the total study group were judged failures and six of the patients had been receiving preoperative narcotics. Patient response was very favorable and pain relief was good to excellent, especially in one group with working stimulators (p is less than 0.008). Patients with known malignant disease did not respond as well as those with benign disease although anxiety may have been an important factor here. Use of the transcutaneous electrical stimulator would seem particularly worthwhile for patients undergoing elective abdominal operations for benign disease with no history of narcotic usage. Briefing the patient preoperatively on the potential value of transcutaneous electrical stimulation as a method of pain relief may improve end-results.

Adult↗
PubMed1977

Muscle fiber number in immobilization atrophy.

Eight Sprague-Dawley rats 10 to 12 weeks of age had one limb immobilized by plaster in knee flexion and ankle plantar flexion for four weeks. The soleus muscles from the control and immobilized limbs were excised and frozen. The technique used insured that cross sections subsequently cut and stained would contain all the fibers extending from the origin to the insertion aponeuroses. The total number of muscle fibers per muscle was counted from 25 to 50 photomicrographs made for each muscle cross section. Paired comparisons of total muscle fibers in control and immobilized muscles revealed no significant differences. The total number of fibers in control and immobilized soleus muscles was 2812 +/- 521 and 2930 +/- 403, respectively. Therefore, muscle fiber loss does not occur in disuse atrophy produced by external immobilization as has been reported.

Animals↗
PubMed1976

Revised laboratory manual helps solve problems.

This paper describes a project to design a laboratory manual which could be easily understood and used by both those who work in and those who utilize the laboratory in a large teaching hospital complex. Results indicated increased employee knowledge of laboratory policies and procedures, and an improved relationship between patient units and the laboratory.

Alabama↗
PubMed1975

Age-dependent characteristics of compensatory renal growth.

The age-dependent characteristics of compensatory renal growth were studied in neonatal, weanling and young adult rats. Compensatory growth was demonstrated to be greater in young, sexually immature animals than in adults following unilateral nephrectomy. In the four-week interval following surgery in 21-day-old weanling rats, renal mass increased 240% in control animals (group A) and 407% after unilateral nephrectomy (group B). In similarly prepared adult animals, renal weight increased 31 and 81% in the same groups, respectively. The remarkable response in compensatory growth achieved by the young animal was further demonstrated by a greater absolute increase in renal mass in the experimental kidney of young rats compared to adults. Further studies were performed to determine whether the mechanism of compensatory growth in young rats involved formation of new nephrons. The total glomerular count in the remaining kidney of rats after removal of one kidney at 5 (neonatal) and 21 (weanling) days of life did not differ from the value obtained in control neonatal, weanling or adult kidneys. These data indicate that compensatory renal hypertrophy is age-dependent and is greater in young animals. The mechanism for enhanced compensatory renal growth in young animals does not involve glomerular neogenesis since there was no evidence for formation of additional nephrons following nephrectomy either in weanling or neonatal animals.

Aging↗
PubMedDate not supplied

Do saxitoxin-like substances have a role in scombrotoxicosis?

Evidence is presented which establishes that mackerel fed in captivity can, by relay from contaminated shellfish via sand eels, accumulate paralytic shellfish poisons (PSP) in the edible flesh at a level (250 micrograms saxitoxin equivalents per kg) similar to that in the contaminated shellfish. Data from ELISAs performed independently in two laboratories show that commercial mackerel fillets which have been associated with incidents of scombrotoxicosis contained 0.02-1.30 micrograms saxitoxin equivalents per kg, concentrations some two to four orders of magnitude below that normally detectable by the mouse bioassay. The doses, expressed as saxitoxin equivalents, administered inadvertently during volunteer testing of such fillets ranged up to 0.5 ng/kg bw, at least four orders of magnitude less than the fatal oral dose for an adult. The doses associated with the rapid induction of nausea/vomiting and/or diarrhoea, 0.11-1.0 ng/kg bw, could not be distinguished from the doses which failed to produce such symptoms in susceptible volunteers (up to 0.5 ng/kg bw). Factors that might explain this lack of correlation between dose (saxitoxin equivalents) and volunteer response are discussed along with previously published reports of PSP relay through the food web. It is suggested that the relay of algal toxins, particularly PSP, but possibly in combination with diarrheic shellfish poisons, may be responsible for scombrotoxicosis.

Animals↗