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Biomedical subjects

M Waldron

Publications and source records attributed to M Waldron.

At least 19 recordsLinked to original sources
PubMed2006

Insulin sensitivity, fat distribution, and adipocytokine response to different diets in lean and obese cats before and after weight loss.

Obesity is a major health problem in cats and a risk factor for diabetes. It has been postulated that cats are always gluconeogenic and that the rise in obesity might be related to high dietary carbohydrates. We examined the effect of a high-carbohydrate/low-protein (HC) and a high-protein/low-carbohydrate (HP) diet on glucose and fat metabolism during euglycemic hyperinsulinemic clamp, adipocytokines, and fat distribution in 12 lean and 16 obese cats before and after weight loss. Feeding diet HP led to greater heat production in lean but not in obese cats. Regardless of diet, obese cats had markedly decreased glucose effectiveness and insulin resistance, but greater suppression of nonesterified fatty acids during the euglycemic hyperinsulinemic clamp was seen in obese cats on diet HC compared with lean cats on either diet or obese cats on diet HP. In contrast to humans, obese cats had abdominal fat equally distributed subcutaneously and intra-abdominally. Weight loss normalized insulin sensitivity; however, increased nonesterified fatty acid suppression was maintained and fat loss was less in cats on diet HC. Adiponectin was negatively and leptin positively correlated with fat mass. Lean cats and cats during weight loss, but not obese cats, adapted to the varying dietary carbohydrate/protein content with changes in substrate oxidation. We conclude that diet HP is beneficial through maintenance of normal insulin sensitivity of fat metabolism in obese cats, facilitating the loss of fat during weight loss, and increasing heat production in lean cats. These data also show that insulin sensitivity of glucose and fat metabolism can be differentially regulated in cats.

Adiponectin↗
PubMed2006

Fatty acid turnover, substrate oxidation, and heat production in lean and obese cats during the euglycemic hyperinsulinemic clamp.

Simultaneous application of the euglycemic hyperinsulinemic clamp (EHC) and indirect calorimetry was used to examine heat production, fat, and glucose metabolism in lean and obese adult neutered male and female cats. The results show that in lean insulin-sensitive cats glucose oxidation predominated during fasting, whereas lipid oxidation became more prominent in obese cats. Insulin infusion during the EHC in lean cats and obese male cats led to a large increase in glucose oxidation, glycogenesis, and lipogenesis. It also led to an increase in glucose oxidation and glycogenesis in obese female cats but it was significantly less compared to lean cats and obese males. This indicates that obese females show greater metabolic inflexibility. In obese cats of either gender, insulin caused greater suppression of non-esterified fatty acids compared to lean cats suggesting that obese cats show greater fatty acid clearance than lean cats. The heat production per metabolic size was lower in obese cats than lean cats. This would perpetuate obesity unless food intake is decreased. The higher glucose oxidation rate in obese neutered male cats suggests that they are able to replete their glycogen and lipid stores at a faster rate than females in response to insulin and it implies that they gain weight more rapidly. Further studies are needed to investigate if the different response to insulin of male cats is involved in their higher risk to develop diabetes.

Adaptation, Physiological↗
PubMed2006

Assessment and mathematical modeling of glucose turnover and insulin sensitivity in lean and obese cats.

Insulin sensitivity (SI) of glucose disposal can be quantified with the euglycemic hyperinsulinemic clamp (EHC) with tracer glucose infusion. True steady state is, however, difficult to achieve, and non-steady state analysis of EHC data is preferred. This analysis requires information on glucose kinetics that can be obtained from bolus injection of cold and tracer glucose. The aim of this study was to assess glucose kinetics in cats. Mathematical modeling and non-steady state analysis was applied to assess effects of obesity on glucose turnover, glycolysis/glycogen synthesis, SI, and inhibition of endogenous glucose production (EGP) in lean cats (L) and obese cats (O). D-[3-(3)H]-glucose kinetics and 3H-H2O production were analyzed in 4 L and 4 O with three-compartment modeling. Frequently sampled insulin-modified intravenous glucose tolerance tests (FSIGT) with minimal model analysis were performed in 5L and 3 O to assess glucose kinetics and SI. EHC was performed in 10 L and 10 O with primed-constant infusion of 3H-glucose. Data were analyzed with a modified minimal model segregating suppression of EGP by insulin using a non-linear mixed-effects population approach. FSIGT provided estimates of SI, glucose effectiveness SG, and distribution volume. EHC provided estimates of SI, SG, glycolysis, and suprabasal insulin concentration for 50% EGP inhibition. Obesity appears to affect glucose distribution but not utilization at basal insulin, and reduces SI estimated by FSIGT and EHC. Differences in SI between FSIGT and EHC depend on different descriptions of EGP inhibition by insulin. Finally, glucose disposal at basal insulin appears to occur entirely through glycolysis, whereas significant amounts of glucose are sequestrated from oxidation during EHC.

Animals↗
PubMed2005

Training and manpower issues for specialist registrars in paediatrics. How are we doing and where are we going?

All Irish paediatric higher specialist trainees' opinions about the paediatric higher specialist training (HST) scheme and related manpower issues were surveyed. Information was obtained on 1) trainees' level of satisfaction with HST, 2) their ultimate career ambitions including location of final posts, 3) attitudes to both flexible training and consultancies and 4) demographics to assess the significance of gender variations. Fifty-two eligible trainees were identified using the Royal College of Physicians of Ireland database. The survey was administered as an anonymous postal survey. The response rate was 88%. Results indicated a high level of satisfaction with HST (78%) overall although problems were noted with the half-day release programme as only 63% were facilitated. Only 30% wish to practice as subspecialists, 76% of trainees wish to work in an urban hospital and 43.5% desire a flexible consultancy suggesting an incompatibility of trainees' desires with current Irish medical manpower policy. To address these difficulties we suggest establishing more rigorous audit of training posts to ensure deficiencies are corrected and the establishment of flexible training to address gender imbalance and to promote the concept of consultant job sharing.

Adult↗
PubMed2004

The MELAS syndrome. Review of the literature: the role of the otologist.

The mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a rare congenital disorder of mitochondrial DNA (mt-DNA). Patients with this syndrome may present to the otolaryngologist with sensorineural hearing loss (SNHL), which is genetic in origin. A high index of suspicion is required because this hearing loss is part of a syndrome for which early diagnosis and intervention is required.

DNA, Mitochondrial↗
PubMed2001

An ALS-like syndrome with new HIV infection and complete response to antiretroviral therapy.

A 32-year-old woman presenting with a rapidly progressive ALS-like syndrome was found to be HIV positive with a CD4 count of 44/mm(3). The patient recovered completely during 1 year after treatment with nelfinavir, zidovudine, and lamivudine, and recovery is sustained nearly 4 years later. Recovery was accompanied by HIV RNA becoming undetectable in plasma and CSF.

Adult↗
PubMed2000

Nonshared environment: a theoretical, methodological, and quantitative review.

When genetic similarity is controlled, siblings often appear no more alike than individuals selected at random from the population. Since R. Plomin and D. Daniels' seminal 1987 review, it has become widely accepted that the source of this dissimilarity is a variance component called nonshared environment. The authors review the conceptual foundations of nonshared environment, with emphasis on distinctions between components of environmental variance and causal properties of environmental events and between the effective and objective aspects of the environment. A statistical model of shared and nonshared environmental variables is developed. A quantitative review shows that measured nonshared environmental variables do not account for a substantial portion of the nonshared variability posited by biometric studies of behavior. Other explanations of the preponderance of nonshared environmental variability are suggested.

Animals↗
PubMed1995

Early-onset chronic renal failure as a presentation of infantile nephropathic cystinosis.

We report an 18-month-old girl who presented in chronic renal failure after an illness characterised by protracted diarrhoea, poor weight gain and anaemia. There were no symptoms and signs suggestive of a renal Fanconi syndrome, but a diagnosis of nephropathic cystinosis was suggested by renal biopsy and confirmed by an elevated leucocyte cystine concentration. We suggest that the diagnosis of cystinosis should be considered in any child with chronic renal failure of unknown aetiology.

Cystinosis↗
PubMed1993

Oculocerebral hypopigmentation syndrome associated with Bartter syndrome.

We describe a 20-year-old man with tyrosinase-negative oculocutaneous albinism, mental retardation, epilepsy, sensorineural deafness, ataxia, and Bartter syndrome. When combined, these neurocutaneous and renal findings form a previously unreported combination. The neurological and cutaneous manifestations of this case are distinctly different from those of the syndrome first reported by Cross et al. [1967]. The literature is reviewed and an attempt is made at classifying the oculocerebral hypopigmentation syndromes.

Adult↗
PubMed1992

Intraglomerular foam cells and human focal glomerulosclerosis.

Experimental evidence suggests a pathogenetic role for lipids in focal glomerulosclerosis (FGS) analogous to atherosclerosis. As foam cells (FC) are an important factor in atherosclerosis, a retrospective comparative study was done to evaluate the significance of intraglomerular FC in human FGS. Glomerular FC infiltration was evaluated in 115 biopsies of FGS, 120 biopsies of membranous glomerulonephritis (MGN) and 50 biopsies of minimal-change disease (MCD). Selected clinical and laboratory data collected at about the time of biopsy were reviewed. The proportion of biopsies showing glomerular FC was much higher in FGS (70%) than in either MGN (12%) or MCD (0%) p less than 0.001. The mean percent (+/- SD) of glomeruli with FC per biopsy was significantly greater in FGS (7.9 +/- 9.9) than in MGN (2.0 +/- 7.8; p less than 0.0001). Of the 14 MGN biopsies with FC, 13 showed superimposed FGS. Mean serum total cholesterol and triglyceride were not significantly higher in FGS than in either MGN or MCD. The results demonstrate a close association of glomerular FC infiltration with FGS.

Adult↗
PubMed1990

Combined endoscopic cytology and biopsies in the diagnosis of duodenal malignancy.

The value of combined cytohistochemical examination in the diagnosis of malignant duodenal lesions was assessed in 78 patients with suspicious duodenal lesions seen at endoscopy. Cytological smears were taken using the direct-vision brushing technique and all were processed by the same experienced cytologist. Duodenal malignancy was confirmed histologically in four patients. Endoscopic biopsy was positive for malignancy in three of the patients and cytology was suspicious of malignant change in two patients and positive for malignant change in one patient. Cytology alone confirmed the diagnosis of malignancy in one patient. The cumulative diagnostic yield using both biopsy and cytology was 100%.

Biopsy↗
PubMed1984

Early history of parenteral nutrition.

A historical review is presented of a number of aspects of early animal experiments and clinical trials dealing with the i.v. infusion of whole blood and milk; the nutritional use of i.v. erythrocytes, plasma proteins, protein hydrolysates, amino acids, and glucose; and development and use of i.v. fat emulsions. A brief description of the experience with the nutritional use of i.v. ethyl alcohol is also presented. The important studies beginning in the 1960's by Dudrick, Rhoads, Vars, and Wilmore are described elsewhere by them.

Amino Acids↗
PubMed1983

Measuring creativity through computer graphics of hearing-impaired children.

The purpose of this study was to investigate variables affecting visual creativity of 31 hearing-impaired children through the medium of computer graphics. These children ranged in age from 8.0 to 15.9 yr. 16 subjects attended total-communication educational programs and 15 subjects attended aural/oral classes. Each subject worked independently at a computer terminal equipped with a graphics menu developed for a subject's use. Hardcopy printouts of four images per subject were evaluated for creativity, aesthetics, and imagery. Analysis suggested that creativity among hearing-impaired children is influenced by age and communication mode used in the educational setting.

Adolescent↗
PubMedDate not supplied

Genetic conditions in the Irish Roma gypsy population.

Roma gypsy represent a new Irish ethnic minority population with a distinct cultural and racial heritage. There is a strong Roma tradition of consanguinity, which can increase the likelihood of having a child affected by an autosomal recessive disorder. We describe 6 patients from the Roma community who had presented with 4 different autosomal recessive conditions not previously seen in the Irish population, Chronic Granulomatous Disease, HMSN-Russe, and two multiple malformation syndromes.

Child↗