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Biomedical subjects

John Pickup

Publications and source records attributed to John Pickup.

7 recordsLinked to original sources
PubMed2005

Uncoupling of nutrient metabolism from insulin secretion by overexpression of cytosolic phospholipase A(2).

We have generated MIN6 beta-cells that stably overexpress cytosolic phospholipase A(2) (cPLA(2)) and show a ninefold increase in cPLA(2) activity. Overexpression of cPLA(2) did not affect the capacity of MIN6 cells to show elevations in intracellular Ca(2+) concentration ([Ca(2+)](i)) in response to tolbutamide and KCl, and these depolarizing stimuli produced insulin secretion profiles in cPLA(2)-overexpressing cells similar to those they produced in passage-matched nontransfected MIN6 cells. However, cPLA(2)-overexpressing MIN6 cells did not respond to elevations in extracellular glucose with increases in ATP, [Ca(2+)](i), or insulin secretion. Nontransfected MIN6 cells showed a rapid and sustained increase in NAD(P)H autofluorescence in response to 25 mmol/l glucose, and this was reduced by approximately 95% in MIN6 cells overexpressing cPLA(2). This effect was mimicked in nontransfected MIN6 cells by p-(trifluoromethoxy) phenylylhydrazone, a mitochondrial uncoupler. Quantitative RT-PCR indicated that mRNA for uncoupling protein-2 (UCP-2) was increased in the cPLA(2)-overexpressing MIN6 cells, and this could be prevented by exposure to 100 mumol/l methyl arachidonyl fluorophosphate, a cPLA(2) inhibitor. Glucose caused a decrease in rhodamine 123 fluorescence in control cells, but not in those overexpressing cPLA(2), consistent with the transfected cells being unable to maintain mitochondrial proton gradients as a consequence of UCP-2 upregulation. Our data indicate that overexpression of cPLA(2) results in severe impairment of the calcium and secretory responses of beta-cells to glucose through upregulation of UCP-2 and uncoupling of mitochondrial metabolism from ATP generation.

Animals↗
PubMed2004

Daily stress and glycaemic control in Type 1 diabetes: individual differences in magnitude, direction, and timing of stress-reactivity.

The aim of this study was to investigate the relationships between daily stress and glycaemic control in 54 people with Type 1 diabetes over 21 days. Measures included daily reports of stress (hassles), four-times-daily blood glucose measurements, and HbA1c levels. Time-series analyses revealed considerable variation between individuals in the nature and extent of blood glucose response to stress (stress-reactivity). In approximately one-third of the sample, stress was significantly associated with either same- or next-day blood glucose levels (r-range: -0.79 to 0.58). The majority of stress-reactive individuals (20.4% of the sample) demonstrated a positive association between hassles and same-day blood glucose levels. A much less common effect was found in two individuals (3.7%), where hassles were related to decreased same-day blood glucose. 'Stress-reactive' individuals tended to have high HbA1c values at baseline (t(52) = 2.2; P < 0.05), and significant relationships between emotion-focused coping and blood glucose levels (r = 0.93; P < 0.01). In conclusion, although a significant majority of this sample was resistant to the effects of stress, marked individual differences were found in the nature and extent of stress-reactivity. Our study goes beyond other published results as it is longitudinal, uses time-series analyses and includes a relatively larger sample. Clinicians need to be aware of these individual differences in order to advise patients about anticipating and preventing stress-related disruptions of glycaemic control.

Adaptation, Psychological↗
PubMed2002

Glycaemic control with continuous subcutaneous insulin infusion compared with intensive insulin injections in patients with type 1 diabetes: meta-analysis of randomised controlled trials.

OBJECTIVE: To compare glycaemic control and insulin dosage in people with type 1 diabetes treated by continuous subcutaneous insulin infusion (insulin infusion pump therapy) or optimised insulin injections. DESIGN: Meta-analysis of 12 randomised controlled trials. PARTICIPANTS: 301 people with type 1 diabetes allocated to insulin infusion and 299 allocated to insulin injections for between 2.5 and 24 months. MAIN OUTCOME MEASURES: Glycaemic control measured by mean blood glucose concentration and percentage of glycated haemoglobin. Total daily insulin dose. RESULTS: Mean blood glucose concentration was lower in people receiving continuous subcutaneous insulin infusion compared with those receiving insulin injections (standardised mean difference 0.56, 95% confidence interval 0.35 to 0.77), equivalent to a difference of 1.0 mmol/l. The percentage of glycated haemoglobin was also lower in people receiving insulin infusion (0.44, 0.20 to 0.69), equivalent to a difference of 0.51%. Blood glucose concentrations were less variable during insulin infusion. This improved control during insulin infusion was achieved with an average reduction of 14% in insulin dose (difference in total daily insulin dose 0.58, 0.34 to 0.83), equivalent to 7.58 units/day. CONCLUSIONS: Glycaemic control is better during continuous subcutaneous insulin infusion compared with optimised injection therapy, and less insulin is needed to achieve this level of strict control. The difference in control between the two methods is small but should reduce the risk of microvascular complications.

Blood Glucose↗
PubMed2002

Continuous subcutaneous insulin infusion at 25 years: evidence base for the expanding use of insulin pump therapy in type 1 diabetes.

Continuous subcutaneous insulin infusion (CSII) is used in selected type 1 diabetic subjects to achieve strict blood glucose control. A quarter of a century after its introduction, world-wide use of CSII is increasing. We review the evidence base that justifies this increase, including effectiveness compared with modern intensified insulin injection regimens and concern about possible complications. Review of controlled trials shows that, in most patients, mean blood glucose concentrations and glycated hemoglobin percentages are either slightly lower or similar on CSII versus multiple insulin injections. However, hypoglycemia is markedly less frequent than during intensive injection therapy. Ketoacidosis occurs at the same rate. Nocturnal glycemic control is improved with insulin pumps, and automatic basal rate changes help to minimize a prebreakfast blood glucose increase (the "dawn phenomenon") often seen with injection therapy. Patients with "brittle" diabetes characterized by recurrent ketoacidosis are often not improved by CSII, although there may be exceptions. We argue that explicit clinical indications for CSII are helpful; we suggest the principal indications for health service or health insurance-funded CSII should include frequent, unpredictable hypoglycemia or a marked dawn phenomenon, which persist after attempts to improve control with intensive insulin injection regimens. In any circumstances, candidates for CSII must be motivated, willing and able to undertake pump therapy, and adequately psychologically stable. Some diabetic patients with well-defined clinical problems are likely to benefit substantially from CSII and should not be denied a trial of the treatment. Their number is relatively small, as would therefore be the demand on funds set aside for this purpose.

Blood Glucose↗
PubMed2002

"Too clean for our own good?": current issues in home hygiene.

The public is confused by apparently conflicting messages about the need for hygiene to prevent food poisoning and other infectious intestinal disease (IID) and the hypothesis that the increase in atopic disease may be linked to lack of exposure to microbes in early childhood. The consensus of hygiene experts is that the public needs to understand what constitutes effective hygiene and how to target key household areas. Handwashing is particularly important, as are cleanliness and disinfection of food preparation surfaces. The issues are discussed and practical tips are given to pass on to families.

Cooking↗