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Biomedical subjects

M Ball

Publications and source records attributed to M Ball.

At least 19 recordsLinked to original sources
PubMed1995

Individual variation in plasma cholesterol response to dietary saturated fat.

OBJECTIVE: To determine the extent to which plasma lipid concentrations of individuals are consistently sensitive to changes in saturated fats; to examine whether groups that consistently have large or small responses can be defined; and to identify factors which predict response of lipids to dietary change. DESIGN: A double crossover design in which two diets (S, providing 21% energy from saturated fat, and P, providing 10%) were followed for periods of six weeks in the sequence SPSP or PSPS. SETTING: 67 free living subjects, total cholesterol 5.5-7.9 mmol/l. MAIN OUTCOME MEASURES: Relation of cholesterol responses to repeated dietary changes and of potential predictors and cholesterol response. RESULTS: Similar average changes in cholesterol mask a wide range of individual responses. Response was not related to compliance. In all participants the change in cholesterol observed when the nature of dietary fat was changed on the two crossovers was correlated (r = 0.31, P = 0.01); the degree of correlation between the two sets of responses was greater in the 46 consistent responders than in the 21 variable responders (r = 0.71 v r = 0.21). Mean differences in cholesterol between diet S and diet P during the two crossovers were 1.16 (SD 0.35) mmol/l and 0.95 (0.26) mmol/l for consistent hyperresponders and 0.18 (0.26) mmol/l and 0.18 (0.25) mmol/l for consistent minimal responders. In consistent responders, changes in total cholesterol in response to increasing saturated fats correlated with baseline cholesteryl ester transfer activity (r = 0.32, P = 0.03); total cholesterol (r = 0.37, P = 0.01); triglycerides (r = 0.30, P = 0.04); and apolipoprotein B (r = 0.54, P = 0.01). CONCLUSIONS: There is a degree of consistency in cholesterol response to instructions to change dietary fat which is not explained by dietary compliance, and there are groups of consistent hyperresponders and minimal responders within a population of hypercholesterolaemic individuals. Several factors predicting response have been identified. These results have relevance to dietary approaches aimed at reducing the lipoprotein mediated risk of coronary heart disease.

Adult↗
PubMed1995

Dioxin concentrations in the blood of workers at municipal waste incinerators.

OBJECTIVES: Increased concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) in pooled blood samples from workers at municipal waste incinerators have been reported. This study was undertaken to confirm these results in individual blood samples from potentially exposed and unexposed workers at municipal waste incinerators compared with matched unexposed controls and compared with concentrations in the slag and fly ash from the municipal waste incinerators. METHODS: Concentrations of PCDDs and PCDFs were determined in the blood of 10 workers from an old municipal waste incinerator without adequate pollution controls, 11 workers from a newer incinerator with modern pollution controls, and 25 controls from the general population group matched for age (+/- 10 years), sex, and race, and in the slag and fly ash from the older incinerator. RESULTS: Significant increases of certain PCDDs and PCDFs were found in the blood of the workers from the older incinerator compared with the controls as follows: octaCDD (1051 (438) v 637 (344), P < 0.001), hexaCDF (52.3 (28.7) v 30.2 (18.2), P < 0.01), heptaCDF (43.9 (30.4) v 22.7 (12.4), P < 0.001), total PCDDs (1262 (484) v 825 (454), P < 0.001), total PCDFs (133.0 (68.1) v 93.7 (36.7), P < 0.05), and total PCDD/Fs (1395 (537) v 918 (437), P < 0.001). The workers from the older incinerator with the greatest exposure were found to have the most significant increases of the blood PCDDs and PCDFs, and the pattern of increased PCDD and PCDF congeners in the blood corresponded to the pattern in the incinerator slag and ash. No significant differences were found between the blood concentrations of the workers at the newer incinerator and the controls. CONCLUSION: Occupational exposure to slag and fly ash from municipal waste incinerators may increase the blood concentrations of PCDDs and PCDFs. Modern pollution control technology in new incinerators may be able to minimise potential exposure to slag and fly ash and thus the absorption of PCDDs and PCDFs from this source.

Adult↗
PubMed1994

Characterization of a single glycosylated asparagine site on a glycopeptide using solid-phase Edman degradation.

The characterization of site-specific glycosylation is traditionally dependent on the availability of suitable proteolytic cleavage sites between each glycosylated residue, so that peptides containing individual glycosylation sites are recovered. In the case of heavily glycosylated domains such as the O-glycosylated mucins, which have no available protease sites, this approach is not possible. Here we introduce a new method to gain site-specific compositional data on the oligosaccharides attached to a single amino acid. Using a model glycopeptide from a mutant human albumin Casebrook, glycosylated PTH-Asn was recovered after sequential solid-phase Edman degradation, subjected to acid hydrolysis and the sugars were identified by high performance anion exchange chromatography with pulsed amperometric detection. The PTH-Asn(Sac) derivative was further characterized by ionspray mass spectrometry. Comparison between an endoproteinase Glu-C glycopeptide and a tryptic glycopeptide showed that the oligosaccharide attached to Asn494 was stable after at least 10 cycles of Edman degradation.

Amino Acid Sequence↗
PubMed1994

Metabolic effects of alterations in meal frequency in hypercholesterolaemic individuals.

It has been suggested that the metabolic consequences of a given diet may depend in part on the frequency with which meals are eaten. To investigate the effects of meal frequency on plasma lipid metabolism, 16 free-living hypercholesterolaemic men and women consumed their usual diet as 3 or 9 meals/day in random order for 4 weeks. Dietary macronutrient intake and body weight remained similar on the 2 regimens. Fasting plasma lipids were measured after 2, 3 and 4 weeks on each regimen and there were no significant differences in the fasting concentrations of plasma total, LDL, and HDL cholesterol, triglycerides, apolipoprotein A-I and B and the ratio of total: LDL and LDL:HDL cholesterol (HDL-C) on the two diets. The mean (+/- S.D.) fasting total cholesterol was 6.73 +/- 0.74 and 6.81 +/- 0.88 mmol/l on 3 and 9 meals/day, respectively and LDL-C was 4.77 +/- 0.66 and 4.87 +/- 0.78 mmol/l, respectively. There was also no significant variation in the response of plasma triglycerides or serum insulin to a high fat meal following a 3 week adaptation to regimens of 3 and 9 meals/day. Finally the 24 h urinary output of C-peptide was similar on each diet. The consumption of isoenergetic diets as 3 and 9 meals/day did not influence fasting plasma lipid levels, C-peptide excretion or the plasma triglyceride response to a high fat meal of a group of free living hypercholesterolaemic subjects.

Adult↗
PubMed1992

Androgenic-anabolic steroid abuse and platelet aggregation: a pilot study in weight lifters.

The abuse of anabolic-androgenic steroids by athletes has recently been associated with the development of myocardial infarction and stroke. Because platelets play a pathogenic role in these disorders, the authors hypothesized that androgenic steroid abuse among weight lifters was associated with increased platelet aggregation as measured in vitro. Twenty-eight study participants were recruited. Twelve denied current androgen use. However, 8 of these 12 tested positive for urinary androgens. Nonsignificant trends toward increased platelet counts and increased platelet aggregation to adenosine diphosphate were noted when androgen users were compared to nonusers. However, when stratified by age, older (greater than 22 years) androgen users required lower concentrations of collagen to produce 50% aggregation of test platelets than did younger (less than or equal to 22 years) androgen users (1.47 versus 3.35 micrograms/ml; p = .01). Further subgroup analysis revealed nonsignificant trends toward increased adenosine diphosphate-induced aggregability and nonsignificant trends in the platelet count in older weight lifters. Subsequent studies using collagen threshold aggregometry revealed no age-dependent effect in 17 other men (aged 18 to 46 years) not specifically selected for activity (r = .17). This study suggests an association between androgen use, age, and increased platelet sensitivity to collagen in weight lifters and may be helpful in explaining recent thrombotic disease in androgen users. It additionally calls into question the validity of subjective reporting when assessing androgen use among weight lifters.

Adolescent↗
PubMed1992

A pre-embedding reaction method for localizing NADH reductase and succinic dehydrogenase in skeletal muscle.

Paraffin wax embedding methods suitable for demonstrating the distribution of enzyme activity in tissues sections are uncommon; most procedures rely on the use of frozen section techniques. This paper describes a system for demonstrating certain enzymes which involves incubation of the tissue with appropriate substrates before a Paramat wax embedding procedure. While it has distinct merits of its own, the procedure is eminently suitable for use where a cryostat is not available; it can also be readily applied to other enzymes and tissues.

Animals↗
PubMed1992

Should mono- or poly-unsaturated fats replace saturated fat in the diet?

The effects of diets differing in saturated, monounsaturated and polyunsaturated fatty acid composition (SAFA, MUFA and PUFA, respectively) on plasma lipoproteins and factor VIIc were investigated in 28 middle-aged men and women with mild to moderate hyperlipidaemia. The subjects were stabilized on a diet with a total fat content fairly typical of New Zealand, containing approximately 40% energy as fat, before entering a randomized cross-over trial of diets high in PUFA (20% energy; SAFA and MUFA 10% each) or a high MUFA diet (20% energy; SAFA and PUFA 10% each). After 6-week periods on each diet the subjects returned to a high SAFA diet. Body weight and blood pressure remained unchanged during the study. Total and LDL cholesterol, HDL cholesterol and the HDL2 subfraction were significantly lower on both the MUFA and the PUFA diet than on SAFA. However, there were no statistically significant differences in lipoprotein concentrations on the MUFA and PUFA diet. Factor VIIc concentrations were similar on the three diets. The proportion of PUFA in a MUFA diet appears to be a major determinant of the relative lipoprotein response to such a diet. In order to avoid a reduction in HDL-C when replacing SAFA with MUFA it may be necessary to ensure that PUFA does not provide more than about 8% total energy. Thus careful planning is needed to identify the most appropriate foods to replace those rich in SAFA in diets designed to reduce the lipoprotein-mediated risk of coronary heart disease.

Aged↗
PubMed1991

[Diverse aspects of congenital syphilis].

Together with the new rise of recent syphilis in the adult woman, congenital syphilis reappears sporadically in our countries, where prophylactic measures (prenatal serology) are sometimes defeated. It remains much more frequent in developing countries. One should know how to interpret a positive serology in a newborn, as it may only reflect passive transplacental transfer of maternal antibodies. One should on the other hand think of syphilis again when the clinical signs are more or less suggestive, the typical picture not being, by far, the most frequent. In spite of the efficacy of Penicillin G: 50,000 U/kg/day during 10 days, neonatal death rate for congenital syphilis is in the neighbourhood of 10%. Our major effort should therefore be aimed at prevention.

Female↗
PubMed1990

Glycerophosphoethanolamine concentration is elevated in brain of patients with dominantly inherited olivopontocerebellar atrophy.

We measured the concentration of glycerophosphoethanolamine (GPEA), a membrane breakdown product, in autopsied brain of 10 patients with dominantly inherited olivopontocerebellar atrophy (OPCA), a cerebellar ataxia disorder. As compared with the controls, mean GPEA levels were significantly elevated by 37-69% in 11 of the 15 brain areas examined, including extracerebellar brain regions in which no neuronal cell loss could be detected by semiquantitative estimation. Our data suggest the possibility of altered membrane phospholipid metabolism in OPCA which could be a contributing factor in the neuronal cell death.

Adult↗
PubMed1990

Hyperlipidaemia in general practice: three year follow up of an opportunistic screening project.

As part of the national lipid screening project 927 people with a plasma cholesterol level greater than 6.5 mM were detected by screening 4006 men and women aged 25-59 years. Three years later 801 of the 878 patients eligible for a follow-up study (91%) had been followed up at least once. The median number of follow-up visits was two. The bulk of the workload fell on the nursing staff. The mean decrease in cholesterol level was 8-14% in those receiving dietary advice only, 15-25% in those receiving additional drug treatment and 12% for all patients. A proportion of this decrease must be attributable to regression to the mean, loss to follow up when patients were doing well, and the patients' knowledge of their follow-up date. Data on a group of patients not attending for regular follow up suggest that regression to the mean could account for up to 7% of the cholesterol reduction observed. Screening for hyperlipidaemia in general practice is feasible when the necessary infrastructure is provided, but even with a fairly conservative protocol 3% of those screened received drug treatment.

Adult↗
PubMed1989

Prescribed fenoterol and death from asthma in New Zealand, 1981-83: case-control study.

A case-control study was conducted to examine the hypothesis that fenoterol by metered dose inhaler (MDI) increases the risk of death in patients with asthma. The case group comprised 117 patients aged 5-45 who died of asthma between August, 1981, and July, 1983. For each case, 4 controls, matched for age and ethnic group, were selected from asthma admissions to hospitals to which the cases themselves would have been admitted, had they survived. The relative risk of asthma death in patients prescribed fenoterol by MDI was 1.55 (95% CI 1.04-2.33, p = 0.03). The possibility of confounding or effect modification by severity was assessed by consideration of subgroups defined by markers of asthma severity. The fenoterol MDI relative risk was 2.21 (95% CI 1.26-3.88, p = 0.01) in patients prescribed three or more categories of asthma drugs, 2.16 (95% CI 1.14-4.11, p = 0.02) in patients with a hospital admission for asthma during the previous 12 months, and 6.45 (95% CI 2.72-15.3, p less than 0.01) in patients prescribed oral corticosteroids at time of death or admission. In the group of patients with the most severe asthma (defined by a hospital admission during the previous year and prescription of oral corticosteroids) the fenoterol MDI relative risk was 13.29 (95% CI 3.45-51.2, p less than 0.01). After adjustment for severity, no other asthma treatment commonly used in New Zealand seemed to be associated with an increased risk of asthma death. Not all sources of bias can be definitely excluded; however, when considered together with other epidemiological and experimental evidence, these findings are consistent with the hypothesis that use of fenoterol by MDI increases the risk of death in severe asthma.

Acute Disease↗