The in vivo effects of the Pro12Ala PPARgamma2 polymorphism on adipose tissue NEFA metabolism: the first use of the Oxford Biobank.

AIMS/HYPOTHESIS: To investigate the phenotypic effects of common polymorphisms on adipose tissue metabolism and cardiovascular risk factors, we set out to establish a biobank with the unique feature of allowing a prospective recruit-by-genotype approach. The first use of this biobank investigates the effects of the peroxisome proliferator-activated receptor (PPAR) Pro12Ala polymorphism on integrative tissue-specific physiology. We hypothesised that Ala12 allele carriers demonstrate greater adipose tissue metabolic flexibility and insulin sensitivity. MATERIALS AND METHODS: From a comprehensive population register, subjects were recruited into a biobank, which was genotyped for the Pro12Ala polymorphism. Twelve healthy male Ala12 carriers and 12 matched Pro12 homozygotes underwent detailed physiological phenotyping using stable isotope techniques, and measurements of blood flow and arteriovenous differences in adipose tissue and muscle in response to a mixed meal containing [1,1,1-(13)C]tripalmitin. RESULTS: Of 6,148 invited subjects, 1,072 were suitable for inclusion in the biobank. Among Pro12 homozygotes, insulin sensitivity correlated with HDL-cholesterol concentrations, and inversely correlated with blood pressure, apolipoprotein B, triglyceride and total cholesterol concentrations. Ala12 carriers showed no such correlations. In the meal study, Ala12 carriers had lower plasma NEFA concentrations, higher adipose tissue and muscle blood flow, and greater insulin-mediated postprandial hormone-sensitive lipase suppression along with greater insulin sensitivity than Pro12 homozygotes. CONCLUSIONS/INTERPRETATION: This study shows that a recruit-by-genotype approach is feasible and describes the biobank's first application, providing tissue-specific physiological findings consistent with the epidemiological observation that the PPAR Ala12 allele protects against the development of type 2 diabetes.

Adverse physicochemical properties of tripalmitin in beta cells lead to morphological changes and lipotoxicity in vitro.

AIMS/HYPOTHESIS: Long-term exposure of beta cells to lipids, particularly saturated fatty acids in vitro, results in cellular dysfunction and apoptosis (lipotoxicity); this could contribute to obesity-related diabetes. Our aims were to relate cell death to intracellular triglyceride concentration, composition and localisation following incubation of INS1 cells in saturated and unsaturated NEFA in high and low glucose concentrations. MATERIALS AND METHODS: Insulin-producing INS1 cells were cultured (24 h; 3 and 20 mmol/l glucose) with palmitic, oleic or linoleic acids and the resulting intracellular lipids were analysed by gas chromatography and microscopy. Cell death was determined by quantitative microscopy and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and glucose-stimulated insulin secretion by ELISA. RESULTS: All NEFA (0.5 mmol/l, 0.5% albumin) inhibited glucose-stimulated (20 mmol/l) insulin secretion. Cytotoxicity was evident only with palmitic acid (p<0.05), in which case intracellular triglyceride consisted largely of tripalmitin in angular-shaped dilated endoplasmic reticulum. Cytotoxicity and morphological disruption were reduced by addition of unsaturated NEFA. Triglyceride content (control cells; 14.5 ng/mug protein) increased up to 10-fold following incubation in NEFA (oleic acid 153.2 ng/mug protein; p<0.05) and triglyceride and phospholipid fractions were both enriched with the specific fatty acid added to the medium (p<0.05). CONCLUSIONS/INTERPRETATION: In INS1 cells, palmitic acid is converted in the endoplasmic reticulum to solid tripalmitin (melting point >65 degrees C), which could induce endoplasmic reticulum stress proteins and signal apoptosis; lipid-induced apoptosis would therefore be a consequence of the physicochemical properties of these triglycerides. Since cellular triglycerides composed of single species of fatty acid are not likely to occur in vivo, destruction of beta cells by saturated fatty acids could be predominantly an in vitro scenario.

The effects of rosiglitazone on fatty acid and triglyceride metabolism in type 2 diabetes.

AIMS/HYPOTHESIS: We investigated the effects of rosiglitazone on NEFA and triglyceride metabolism in type 2 diabetes. METHODS: In a double-blind, placebo-controlled, cross-over study of rosiglitazone in diet-treated type 2 diabetic subjects, we measured arteriovenous differences and tissue blood flow in forearm muscle and subcutaneous abdominal adipose tissue, used stable isotope techniques, and analysed gene expression. Responses to a mixed meal containing [1,1,1-(13)C]tripalmitin were assessed. RESULTS: Rosiglitazone induced insulin sensitisation without altering fasting NEFA concentrations (-6.6%, p=0.16). Postprandial NEFA concentrations were lowered by rosiglitazone compared with placebo (-21%, p=0.04). Adipose tissue NEFA release was not decreased in the fasting state by rosiglitazone treatment (+24%, p=0.17) and was associated with an increased fasting hormone-sensitive lipase rate of action (+118%, p=0.01). Postprandial triglyceride concentrations were decreased by rosiglitazone treatment (-26%, p<0.01) despite unchanged fasting concentrations. Rosiglitazone did not change concentrations of triglyceride-rich lipoprotein remnants. Adipose tissue blood flow increased with rosiglitazone (+32%, p=0.03). Postprandial triglyceride [(13)C]palmitic acid concentrations were unchanged, whilst NEFA [(13)C]palmitic acid concentrations were decreased (p=0.04). In muscle, hexokinase II mRNA expression was increased by rosiglitazone (+166%, p=0.001) whilst the expression of genes involved in insulin signalling was unchanged. Adipose tissue expression of FABP4, LPL and FAT/CD36 was increased. CONCLUSIONS/INTERPRETATION: Rosiglitazone decreases postprandial NEFA and triglyceride concentrations. This may represent decreased spillover of NEFAs from adipose tissue depots. Decreased delivery of NEFAs to the liver may lead to lowered postprandial triglyceride concentrations. Upregulation of hexokinase II expression in muscle may contribute to insulin sensitisation by rosiglitazone.

Subcutaneous adipose tissue blood flow varies between superior and inferior levels of the anterior abdominal wall.

OBJECTIVE: Blood flow regulation is thought to mediate the metabolic functions of adipose tissue. Different depots, and even different layers within the subcutaneous adipose tissue, may vary in metabolic activity and blood flow. Therefore, we investigated if any differences in subcutaneous adipose tissue blood flow (ATBF) exist at different locations of the anterior abdominal wall. METHODS: ATBF was measured 8-10 cm above or below the umbilicus, at 8-10 cm (both sides) from the midline, in 18 healthy subjects (BMI range 18-33 kg/m(2)). Measurements of ATBF were performed using (133)xenon washout, during a stable baseline period and after ingestion of 75 g of glucose. RESULTS: At baseline, ATBF was greater at the upper level compared to the lower level (4.4+/-0.3 vs 3.8+/-0.2 ml min(-1) 100 g tissue(-1), P=0.005), but was not different between the right and the left sides at either level. ATBF increased in response to oral glucose at all sites. The mean increase at the superior level was also greater than the inferior level (3.5+/-0.7 vs 2.2+/-0.6 ml min(-1) 100 g tissue(-1), P=0.001). CONCLUSIONS: Even at a constant depth and with only 16-20 cm difference between sites, there are significant differences in function of the same adipose depot. These findings have physiological and methodological implications for in vivo metabolic studies of human adipose tissue.

Prior short-term consumption of resistant starch enhances postprandial insulin sensitivity in healthy subjects.

AIMS/HYPOTHESIS: Diets rich in insoluble-fibre are linked to a reduced risk of both diabetes and cardiovascular disease; however, the mechanism of action remains unclear. The aim of this study was to assess whether acute changes in the insoluble-fibre (resistant starch) content of the diet would have effects on postprandial carbohydrate and lipid handling. METHODS: Ten healthy subjects consumed two identical, low-residue diets on separate occasions for 24 h (33% fat; <2 g dietary fibre). Of the diets one was supplemented with 60 g resistant starch (Novelose 260). On the following morning a fibre-free meal tolerance test (MTT) was carried out (59 g carbohydrate; 21 g fat; 2.1 kJ) and postprandial insulin sensitivity (SI(ORAL)) assessed using a minimal model approach. RESULTS: Prior resistant starch consumption led to lower postprandial plasma glucose (p=0.037) and insulin (p=0.038) with a higher insulin sensitivity(44+/-7.5 vs 26+/-3.5 x 10(-4) dl kg(-1) min(-1) per micro Uml(-1); p=0.028) and C-peptide-to-insulin molar ratio (18.7+/-6.5 vs 9.7+/-0.69; p=0.017). There was no effect of resistant starch consumption on plasma triacylglycerol although non-esterified fatty acid and 3-hydroxybutyrate levels were suppressed 5 h after the meal tolerance test. CONCLUSION: Prior acute consumption of a high-dose of resistant starch enhanced carbohydrate handling in the postprandial period the following day potentially due to the increased rate of colonic fermentation.

No excess of factor V:Q506 genotype but high prevalence of anticardiolipin antibodies without antiendothelial cell antibodies in retinal vein occlusion in young patients.

Factor V:Q506 (factor V Leiden) is associated with venous thrombosis and has been reported to be a risk factor for retinal vein occlusion (RVO). Anticardiolipin antibodies (ACA), also associated with RVO, are a marker for the prothrombotic condition antiphospholipid syndrome, in which antiendothelial antibodies (AECA) are also frequently present. This study reviewed 45 younger patients 10 GPL units); in 6 of these, the titre was >20 GPL units (population reference range = 0-10 GPL units). No patient had antiendothelial cell reactivity. The low-titre ACA may therefore represent a non-specific response to vascular injury.

Choosing among alternative programs for poor children.

Many public programs serve poor children. By setting budgets, benefit levels, and program rules, policymakers decide how many children will receive benefits and which benefits they will receive. Making these choices in a rational way is difficult, given the noncomparability of different types of program benefits and the limited information available about the effects these programs have on poor children. This article suggests four criteria (efficiency, return on investment, incentives, and equity) for evaluating and comparing public programs for poor children, and provides an overview of the patchwork of information that is currently available about the effects of eight large federal programs using these criteria. Some broad themes emerge. First, several programs that target specific benefits directly to children have been shown to have positive effects on a range of outcomes. Second, even before the current round of welfare reform, the mix of federal support available to poor children had changed in a way that put more emphasis on providing benefits in kind. Finally, more must be learned about the effects of programs for poor children before sweeping policy recommendations can be made. This article concludes with policy recommendations that can be supported by the available evidence.

The inevitable partnership between healthcare practice and healthcare buildings.

In this paper, the author points out the tightly-woven relationship between the healthcare provider and the facilities in which the care takes place. This relationship has evolved from the earliest days of organized medicine. Further, he asserts that in these days of reform and of heightened consumer expectations, the facilities controlled by the provider are among his most important assets. Examples cited cover intensive care settings, ambulatory care, and patient-focused care concepts. The author concludes by speculating on the form that the healthcare facilities of the future might take and on some strategies that the provider might follow.

Occult malignancy is associated with venous thrombosis unresponsive to adequate anticoagulation.

The increased incidence of intravascular thrombosis and thromboembolic episodes in patients with malignant disease is well documented. There have, however, been only two reports of covert malignancy in patients who continue to extend their deep vein thrombosis despite apparently adequate anticoagulation. Three patients are described in whom venous thrombosis steadily worsened despite a prothrombin time of at least twice normal. None had either obvious predisposing factors to thromboembolism or a family history of thrombotic disease. Recognition of this phenomenon can be helpful in avoiding delay in diagnosing malignancy in young patients.

Indirect sonographic guidance for epidural anesthesia in obese pregnant patients.

BACKGROUND AND OBJECTIVES: Obesity and edema frequently obscure anatomic landmarks and result in technical difficulties during epidural anesthesia administration. However, the method of indirect sonographic guidance permits identification of the midline by sagittal scan of the laminae of lumbar vertebrae 2, 3, and 4. METHODS: Thirty-six obese women scheduled for elective repeat cesarean delivery were prospectively studied. Use of a 5-MHz transducer positioned with the transducer center site over the second or third interspace allowed measurement of skin-to-lamina distance by the electronic calipers of a Toshiba SAL-32B or RT 3000 GE machine, prediction of needle depth for epidural puncture (EP), and skin marking of the site. After the transducer was removed, a 9.5- or 11.4-cm Tuohy needle was percutaneously advanced perpendicularly from the site until EP was achieved. RESULTS: Needle depth was measured by marker and measure, and epidural anesthesia was successfully administered to all patients. Simple linear regression analysis was performed with strong positive results. Indirect and continuous sonographic guidance studies designed to determine whether sonography reduces complications are planned.

Reversible infertility and Castleman's disease.

Castleman's disease may cause systemic symptoms with biochemical and haematological disturbances (Featherstone et al. 1990). These usually resolve completely soon after surgical removal of the abnormal mass. We report two cases of infertility associated with the systemic disturbances of abdominal Castleman's disease. Both women conceived less than one year after removal of the 'tumour' and delivered normal infants.

Determinants of the initial comfort of hydrogel contact lenses.

A double-masked, randomized study was conducted to determine the effects of power and water content on the initial comfort of hydrogel contact lenses in 10 unadapted subjects. Three lens powers (-0.50, -5.00, and -10.00 D) were used in each of three water contents (38, 55, and 70%). A significant negative correlation (p less than 0.05) was found between lens comfort and lens water content; that is, lower water content lenses of lesser bulk were more comfortable than higher water content lenses. These data will allow practitioners to predict patient awareness to various lens types. When fitting hydrogel lenses to an apprehensive patient who has not worn contact lenses previously, it may be advisable to insert a thin, low water content lens initially, thereby maximizing lens comfort.

Measurement of the depth to the extradural space using ultrasound.

Seventy-five patients requesting extradural analgesia for the relief of pain in labour underwent an ultrasound scan to measure the depth to the extradural space. There was a high degree of correlation between these measurements and the subsequent depth of insertion of the Tuohy needle. The advantages of the technique in clinical practice and as an aid to teaching, are discussed.