Correlation of the leptin:adiponectin ratio with measures of insulin resistance in non-diabetic individuals

AIMS/HYPOTHESIS

Obesity is the dominant cause of insulin resistance. In adult humans it is characterised by a combination of adipocyte hypertrophy and, to a lesser extent, adipocyte hyperplasia. As hypertrophic adipocytes secrete more leptin and less adiponectin, the plasma leptin:adiponectin ratio (LAR) has been proposed as a potentially useful measure of insulin resistance and vascular risk. We sought to assess the usefulness of the LAR as a measure of insulin resistance in non-diabetic white adults.

METHODS

Leptin and adiponectin levels were measured in 2,097 non-diabetic individuals from the Ely and European Group for the Study of Insulin Resistance (EGIR) Relationship between Insulin Sensitivity and Cardiovascular Risk (RISC) study cohorts. LAR was compared with fasting insulin and HOMA-derived insulin sensitivity (HOMA-S) in all individuals and with the insulin sensitivity index (M/I) from hyperinsulinaemic-euglycaemic clamp studies in 1,226 EGIR RISC participants.

RESULTS

The LAR was highly correlated with HOMA-S in men (r = -0.58, p = 4.5 x 10(-33) and r = -0.65, p = 1.1 x 10(-66) within the Ely and EGIR RISC study cohorts, respectively) and in women (r = -0.51, p = 2.8 x 10(-36) and r = -0.61, p = 2.5 x 10(-73)). The LAR was also strongly correlated with the clamp M/I value (r = -0.52, p = 4.5 x 10(-38) and r = -0.47, p = 6.6 x 10(-40) in men and women, respectively), similar to correlations between HOMA-S and the M/I value.

CONCLUSIONS/INTERPRETATION

The leptin:adiponectin ratio is a useful measure of insulin resistance in non-diabetic white adults. These data highlight the central role of adipocyte dysfunction in the pathogenesis of insulin resistance. Given that variations between fasting and postprandial leptin and adiponectin levels tend to be small, the leptin to adiponectin ratio might also have potential value in assessing insulin sensitivity in the non-fasted state.

Adiponectin receptor genes: mutation screening in syndromes of insulin resistance and association studies for type 2 diabetes and metabolic traits in UK populations

AIMS/HYPOTHESIS

Adiponectin is an adipokine with insulin-sensitising and anti-atherogenic properties. Several reports suggest that genetic variants in the adiponectin gene are associated with circulating levels of adiponectin, insulin sensitivity and type 2 diabetes risk. Recently two receptors for adiponectin have been cloned. Genetic studies have yielded conflicting results on the role of these genes and type 2 diabetes predisposition. In this study we aimed to evaluate the potential role of genetic variation in these genes in syndromes of severe insulin resistance, type 2 diabetes and in related metabolic traits in UK Europid populations.

MATERIALS AND METHODS

Exons and splice junctions of the adiponectin receptor 1 and 2 genes (ADIPOR1; ADIPOR2) were sequenced in patients from our severe insulin resistance cohort (n=129). Subsequently, 24 polymorphisms were tested for association with type 2 diabetes in population-based type 2 diabetes case-control studies (n=2,127) and with quantitative traits in a population-based longitudinal study (n=1,721).

RESULTS

No missense or nonsense mutations in ADIPOR1 and ADIPOR2 were detected in the cohort of patients with severe insulin resistance. None of the 24 polymorphisms (allele frequency 2.3-48.3%) tested was associated with type 2 diabetes in the case-control study. Similarly, none of the polymorphisms was associated with fasting plasma insulin, fasting and 2-h post-load plasma glucose, 30-min insulin increment or BMI.

CONCLUSIONS/INTERPRETATION

Genetic variation in ADIPOR1 and ADIPOR2 is not a major cause of extreme insulin resistance in humans, nor does it contribute in a significant manner to type 2 diabetes risk and related traits in UK Europid populations.

PPARGC1A coding variation may initiate impaired NEFA clearance during glucose challenge

AIMS/HYPOTHESIS

The peroxisome proliferator-activated receptor gamma coactivator 1-alpha protein, encoded by the PPARGC1A gene, transcriptionally activates a complex pathway of lipid and glucose metabolism and is expressed primarily in tissues of high metabolic activity such as liver, heart and exercising oxidative skeletal muscle fibre. Ppargc1a-null mice develop systemic dyslipidaemia and hepatic steatosis. In humans, NEFAs downregulate PPARGC1A expression in skeletal muscle. Furthermore, a common non-synonymous coding variant at PPARGC1A (Gly482Ser, rs8192678) is associated with decreased PPARGC1A mRNA levels and increased type 2 diabetes risk.

MATERIALS AND METHODS

In a population-based sample of 691 healthy middle-aged Europids we assessed whether Gly482Ser is associated with levels of NEFA when fasting and in response to an oral glucose challenge. We also assessed the potential effect-modifying role of adipose tissue mass on these phenotypes.

RESULTS

After adjustment for age, sex, fat mass and fat-free mass, the Ser482 allele associated with higher NEFA at 30 min and 2 h and with NEFA AUC (all values p<or=0.02). Furthermore, suggestive evidence of interaction between fat mass and Gly482Ser was observed for fasting NEFA (p=0.059). After stratification by level of obesity, genotype associations were observed in the obese for fasting NEFA (p=0.028) and NEFA at 30 min (p=0.013) and 2 h (p=0.002), and with NEFA AUC (p=0.005), but no significant associations were observed in lean individuals (all values p>0.6).

CONCLUSIONS/INTERPRETATION

Our observations indicate that NEFA clearance is blunted following a glucose load in carriers of the PPARCG1A Ser482 allele. This association is augmented by obesity.

Incidence of Type 2 diabetes in England and its association with baseline impaired fasting glucose: the Ely study 1990-2000

AIM

To determine the incidence of Type 2 diabetes and to examine the effect of different cut-points for impaired fasting glucose (IFG) on diabetes incidence.

METHODS

Population-based longitudinal study (1990-2000) with clinical, anthropometric and biochemical measurements, including an oral glucose tolerance test (OGTT), in 1040 non-diabetic adults aged 40-69 years at baseline. Baseline glucose status was defined as normoglycaemia < 5.6, IFG-lower 5.6-6.0 and IFG-original 6.1-6.9 mmol/l. The all-IFG group included fasting glucose values of 5.6-6.9 mmol/l.

RESULTS

The 10-year cumulative incidence of diabetes was 7.3 per 1000 person-years. Diabetes incidence was 2.4 [95% confidence interval (CI) 1.2, 4.8], 6.2 (4.0, 9.8) and 17.5 (12.5, 24.5) per 1000 person-years in those with normoglycaemia, IFG-lower and IFG-original, respectively. Compared with normoglycaemia, the age/sex-adjusted risk [hazard ratio (HR) and 95% CI] for incident diabetes was greatest in the IFG-original category (HR 6.9; 3.1, 15.2) and increased to a lesser degree in the IFG-lower (HR 2.5; 1.1, 5.7) and all-IFG categories (HR 4.1; 1.9, 8.7). When adjusted for confounding factors, the magnitude and direction of associations persisted, with HR 1.9, 4.4 and 2.9, for the categories IFG-lower, IFG-original and all-IFG, respectively.

CONCLUSIONS

Diabetes incidence is more strongly related to IFG defined as fasting glucose between 6.1 and 6.9 mmol/l than to the lower category of 5.6-6.0 mmol/l, or entire range of 5.6-6.9 mmol/l. Future studies should examine the association of IFG with cardiovascular outcomes, but for diabetes risk our study supports the use of the IFG cut-point at 6.1 mmol/l.

Polymorphisms in the gene encoding sterol regulatory element-binding factor-1c are associated with type 2 diabetes

AIMS/HYPOTHESIS

The sterol regulatory element-binding factor (SREBF)-1c is a transcription factor involved in the regulation of lipid and glucose metabolism. We have previously found evidence that a common SREBF1c single-nucleotide polymorphism (SNP), located between exons 18c and 19c, is associated with an increased risk of type 2 diabetes. The present study aimed to replicate our previously reported association in a larger case-control study and to examine an additional five SREBF1c SNPs for their association with diabetes risk and plasma glucose concentrations.

METHODS

We genotyped six SREBF1c SNPs in two case-control studies (n=1,938) and in a large cohort study (n=1,721) and tested for association with type 2 diabetes and with plasma glucose concentrations (fasting and 120-min post-glucose load), respectively.

RESULTS

In the case-control studies, carriers of the minor allele of the previously reported SNP (rs11868035) had a significantly increased diabetes risk (odds ratio [OR]=1.20 [95% CI 1.04-1.38], p=0.015). Also, three other SNPs (rs2236513, rs6502618 and rs1889018), located in the 5' region, were significantly associated with diabetes risk (OR > or =1.21, p< or =0.006). Furthermore, two SNPs (rs2236513 and rs1889018) in the 5' region were weakly (p<0.09) associated with plasma glucose concentrations in the cohort study. Rare homozygotes had increased (p< or =0.05) 120-min post-load glucose concentrations compared with carriers of the wild-type allele. Haplotype analyses showed significant (p=0.04) association with diabetes risk and confirmed the single SNP analyses.

CONCLUSIONS/INTERPRETATION

In summary, we replicated our previous finding and found evidence for SNPs in the 5' region of the SREBF1c gene to be associated with the risk of type 2 diabetes and plasma glucose concentration.

PARL Leu262Val is not associated with fasting insulin levels in UK populations

AIMS/HYPOTHESIS

PARL, the gene encoding presenilins-associated rhomboid-like protein, maps to chromosome 3q27 within a quantitative trait locus that influences components of the metabolic syndrome. Recently, an amino acid substitution (Leu262Val, rs3732581) in PARL was associated with fasting plasma insulin levels in a US white population (N=1031). This variant was also found to modify the positive association between age and fasting insulin. The aim of this study was to test whether these findings could be replicated in two UK population-based cohorts.

METHODS

Participants from the Medical Research Council Ely and Hertfordshire cohort studies were genotyped for this variant using a SNaPshot primer extension assay and Taqman assay respectively. Full phenotypic and genotypic data were available for 3,666 study participants.

RESULTS

Based on a dominant model, we found no association between the Leu262Val polymorphism and fasting insulin levels (p=0.79) or BMI (p=0.98). We did not observe the previously reported interaction between age and genotype on fasting insulin (p=0.14).

CONCLUSIONS/INTERPRETATION

Despite having greater statistical power, our data do not support the previously reported association between PARL Leu262Val and fasting plasma insulin levels, a measure of insulin resistance. Our findings indicate that this variant is unlikely to be an important contributor to insulin resistance in UK populations.

Studies of the SIM1 gene in relation to human obesity and obesity-related traits

OBJECTIVE

The single-minded 1 (SIM1) is a basic helix-loop-helix transcription factor, which plays a critical role in the development of the paraventricular nucleus (PVN) of the hypothalamus. SIM1-deficient mice have a hypocellular PVN and are severely obese with increased food intake.

DESIGN

We examined whether variants in the SIM1 gene might be associated with severe early-onset obesity in humans. Two hundred and seventy-seven subjects with hyperphagia and severe, early-onset obesity were screened. Association studies with common single-nucleotide polymorphisms (SNPs) in the SIM1 gene were performed in two population-based cohorts.

RESULTS

One novel missense mutation, I128T, was found in one obese subject and not in 192 controls. However, the variant did not co-segregate with obesity in the family. Four SNPs, IVS4+83GA, P352T, A371V and T653T, were also identified. The two common SNPs, P352T and A371V, which are in complete linkage disequilibrium, were genotyped in 981 subjects from a population-based cohort, the Ely Study. An allele frequency of 0.13 was observed. Male subjects carrying the P352T/A371V haplotype were found to have a slightly higher body mass index (BMI; P=0.038). Female subjects homozygous for the haplotype gained more weight over a period of 4.5 and 10 years (P=0.003 and P=0.02, respectively). The association studies were repeated in another population-based cohort, the European Prospective Investigation into Cancer and Nutrition (EPIC) - Norfolk Study with 4869 subjects successfully genotyped. Male subjects homozygous for the P352T/A371V haplotype had slightly higher BMI (P=0.04).

CONCLUSION

Mutations in SIM1 are not commonly found in humans with severe early-onset obesity. The relationship between the common variants in SIM1 with BMI and body weight gain deserves further exploration in other populations.

Elevated plasma adiponectin in humans with genetically defective insulin receptors

CONTEXT

Adiponectin has been suggested to play a role in the etiopathogenesis of at least some forms of insulin resistance, in part based on a strong correlation between plasma levels of adiponectin and measures of insulin sensitivity.

OBJECTIVE

The objective of the study was to establish whether this relationship is maintained at extreme levels of insulin resistance.

DESIGN/SETTING

This was a cross-sectional study in a university teaching hospital of subjects recruited from the United Kingdom and the United States.

PARTICIPANTS

Participants included 75 subjects with a range of syndromes of severe insulin resistance and 872 nondiabetic controls.

OUTCOME MEASURES

Fasting plasma insulin, adiponectin, and leptin were measured.

RESULTS

Unexpectedly, subjects with mutations in the insulin receptor, despite having the most severe degree of insulin resistance, had elevated plasma adiponectin [median 24.4 mg/liter; range 6.6-36.6 (normal adult range for body mass index 20 kg/m(2) = 3-19 mg/liter)], whereas all other subjects had low adiponectin levels (median 2.0 mg/liter; range 0.12-11.2). Plasma leptin in all but one subject with an insulin receptoropathy was low or undetectable [median 0.5 ng/ml; range 0-16: normal adult range for body mass index of < 25 kg/m(2) = 2.4-24.4 (female) and 0.4-8.3 ng/ml (male)].

CONCLUSIONS

We conclude that the relationship between plasma adiponectin and insulin sensitivity is complex and dependent on the precise etiology of defective insulin action and that the combination of high plasma adiponectin with low leptin may have clinical utility in patients with severe insulin resistance as a marker of the presence of a genetic defect in the insulin receptor.

Meta-analysis of the Gly482Ser variant in PPARGC1A in type 2 diabetes and related phenotypes

AIMS/HYPOTHESIS

Peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PPARGC1A) is a transcriptional co-activator with a central role in energy expenditure and glucose metabolism. Several studies have suggested that the common PPARGC1A polymorphism Gly482Ser may be associated with risk of type 2 diabetes, with conflicting results. To clarify the role of Gly482Ser in type 2 diabetes and related human metabolic phenotypes we genotyped this polymorphism in a case-control study and performed a meta-analysis of relevant published data.

MATERIALS AND METHODS

Gly482Ser was genotyped in a type 2 diabetes case-control study (N=1,096) using MassArray technology. A literature search revealed publications that examined Gly482Ser for association with type 2 diabetes and related metabolic phenotypes. Meta-analysis of the current study and relevant published data was undertaken.

RESULTS

In the pooled meta-analysis, including data from this study and seven published reports (3,718 cases, 4,818 controls), there was evidence of between-study heterogeneity (p<0.1). In the fixed-effects meta-analysis, the pooled odds ratio for risk of type 2 diabetes per Ser482 allele was 1.07 (95% CI 1.00-1.15, p=0.044). Elimination of one of the studies from the meta-analysis gave a summary odds ratio of 1.11 (95% CI 1.04-1.20, p=0.004), with no between-study heterogeneity (p=0.475). For quantitative metabolic traits in normoglycaemic subjects, we also found significant between-study heterogeneity. However, no significant association was observed between Gly482Ser and BMI, fasting glucose or fasting insulin.

CONCLUSIONS/INTERPRETATION

This meta-analysis of data from the current and published studies supports a modest role for the Gly482Ser PPARGC1A variant in type 2 diabetes risk.

Gross Motor Function Classification System and outcome tools for assessing ambulatory cerebral palsy: a multicenter study

The relationships between different levels of severity of ambulatory cerebral palsy, defined by the Gross Motor Function Classification System (GMFCS), and several pediatric outcome instruments were examined. Data from the Gross Motor Function Measure (GMFM), Pediatric Orthopaedic Data Collection Instrument (PODCI), temporal-spatial gait parameters, and oxygen cost were collected from six sites. The sample size for each assessment tool ranged from 226 to 1047 participants. There were significant differences among GMFCS levels I, II, and III for many of the outcome tools assessed in this study. Strong correlations were seen between GMFCS level and each of the GMFM sections D and E scores, the PODCI measures of Transfer and Mobility, and Sports and Physical Function, Gait Velocity, and Oxygen Cost. Correlations among tools demonstrated that the GMFM sections D and E scores correlated with the largest number of other tools. Logistic regression showed GMFM section E score to be a significant predictor of GMFCS level. GMFM section E score can be used to predict GMFCS level relatively accurately (76.6%). Study data indicate that the assessed outcome tools can distinguish between children with different GMFCS levels. This study establishes justification for using the GMFCS as a classification system in clinical studies.

Genetic variation in the corticotrophin-releasing factor receptors: identification of single-nucleotide polymorphisms and association studies with obesity in UK Caucasians

OBJECTIVE

To investigate whether genetic variation at the loci encoding the corticotropin-releasing factor receptors-1 and -2 (CRF-R1 and CRF-R2) contributes to human obesity.

DESIGN

The coding region of the CRF-R1 and CRF-R2 genes was screened in 51 severely obese children (body mass index (BMI)>4 kg/m(2) standard deviations above the age-related mean) using denaturing high-performance liquid chromatography and direct nucleotide sequencing. Common polymorphisms that were identified were typed from a UK Caucasian population-based cohort by a PCR-based forced restriction digestion. A repeated measures analysis was used to determine associations between the C861T and G1047A genotypes and anthropometric and biochemical indices relevant to obesity.

RESULTS

In subjects with extreme early-onset obesity, four missense mutations were found, each in a single individual: CRF-R1 (Val161Met) and CRF-R2 (Glu220Asp, Val240Ile and Val411Met). However, none of these missense mutations clearly cosegregated with obesity in family studies. Two common single-nucleotide polymorphisms, C861T (Cys287Cys) in CRF-R1 and G1047A (Ser349Ser) in CRF-R2, were also detected. G1047A did not associate with any obesity-related phenotype. In contrast, carriers of the CRF-R1 polymorphism, C861T, had a significantly higher body mass index (BMI).

CONCLUSION

Mutations in the coding sequence of the CRF-R1 and CRF-R2 genes are unlikely to be a common monogenic cause of early-onset obesity. In an adult UK Caucasian population, the CRF-R1 C861T polymorphism is associated with increased BMI.

Does peroxisome proliferator-activated receptor gamma genotype (Pro12ala) modify the association of physical activity and dietary fat with fasting insulin level?

Peroxisome proliferator-activated receptor gamma (PPARgamma) has a role in controlling adipogenesis and insulin sensitivity. Previous studies have suggested that a common polymorphism (Pro12Ala) in the PPARgamma-2 isoform of this gene may be associated with markers of insulin resistance. We have previously shown that in combination, the relationships with fasting insulin of dietary polyunsaturated to saturated fatty acid ratio (P:S ratio) and physical activity are additive. We have also demonstrated that the association between P:S ratio and fasting insulin level is modified by the Pro12Ala genotype. The purpose of the present study was to investigate whether the Pro12Ala genotype modified the combined relationships of P:S ratio and physical activity level (PAL) on fasting insulin concentration. A population-based cohort of 506 Caucasian men and women aged 31 to 71 years was genotyped for the Pro12Ala polymorphism. P:S ratio was assessed by food-frequency questionnaire (FFQ) and PAL was estimated from 4 days of free-living heart rate monitoring following individual calibration of heart rate against energy expenditure during an exercise stress test. The combined associations of PAL and P:S ratio on fasting insulin level were examined stratified by Pro12Ala genotypes in a dominant model for the Ala allele. Among Pro allele homozygotes, there was no interaction between PAL and P:S ratio on fasting insulin (P =.929). However, in carriers of the Ala allele the association of P:S ratio with fasting insulin was modified by activity level (interaction P = 0.038). In those who were inactive and carried the Ala allele, the age-, sex-, and body mass-adjusted relationship between P:S ratio and log insulin was not significant (beta = -0.03, P =.93). In contrast, in physically active Ala carriers, the association of P:S ratio with log fasting insulin was highly significant (beta = -0.93, P =.004). In conclusion, this study examined the modification by PPARgamma genotype of the association between energy expenditure, P:S ratio, and fasting insulin level, a measure of insulin resistance. These data show that in Pro allele homozygotes the combined associations of P:S ratio and PAL are additive. In contrast, in Ala allele carriers, PAL modifies the association between P:S ratio and fasting insulin level in a multiplicative manner.

The effect of the Gly16Arg polymorphism of the beta(2)-adrenergic receptor gene on plasma free fatty acid levels is modulated by physical activity

The lipolytic effects of catecholamines are mediated through members of the beta(2)-adrenergic receptor (BAR-2) family. Previous studies have suggested that genetic variants in the BAR-2 gene may be associated with obesity in some populations. To our knowledge, no studies have directly examined the effects of this polymorphism on circulating nonesterified fatty acid (NEFA) levels. To explore this issue further, a cohort of 604 Caucasian individuals (aged 40-65 yr) was genotyped for a common polymorphism in the BAR-2 gene (Gly16Arg), and the relationships between genotype, body mass index (BMI), NEFA, and lipid levels were examined. Women bearing the Arg16 allele had higher BMI values (P < 0.01) than Gly16Gly women. Women carriers of the Arg16Arg genotype had lower fasting plasma NEFAs (P < 0.01) and greater suppression of NEFAs (P < 0.01) after an oral glucose load than women bearing the Gly16 allele. In multivariate analysis after adjustment for age, sex, and smoking status, the interaction between the BAR-2 genotype and BMI in determining fasting NEFA concentrations was statistically significant (P < 0.05). The availability of objective measures of total energy expenditure in this population permitted the further examination of interactions, particularly that between genotype and physical activity. In the population as a whole, after adjustment for confounding by age, smoking, and BMI, the effect of the Arg16Arg genotype on the suppression of NEFA levels was modified by physical activity level (P for interaction <0.05). These data suggest the existence in this population of a gene-physical activity interaction on NEFA levels.

Variation in the promoter of the human hormone sensitive lipase gene shows gender specific effects on insulin and lipid levels: results from the Ely study

We previously identified a hormone sensitive lipase (HSL) promoter variant, -60C>G, which in vitro exhibits 40% reduced promoter activity. In this study we examined the effect of the -60C>G on glycemic and lipid measures in the population based Ely study of metabolic function and insulin resistance in 218 middle-aged men and 276 middle-aged women. Adipose tissue HSL is the rate-limiting step in triglyceride lipolysis, generating free fatty acids for energy utilization. HSL is also expressed in pancreatic beta-cells where its activity therefore may affect insulin secretion. In the women, carriers of the HSL -60G allele had significantly lower fasting insulin levels (P=0.0005) and a lower total area under the curve for insulin during the oral glucose tolerance test (P=0.005). There was no demonstrable association in men with these measures of insulin sensitivity but carriers of the -60G allele had significantly lower fasting non-esterified fatty acid (NEFA) levels (P=0.025) and higher low density lipoprotein cholesterol levels (P=0.02) than men who were non-carriers. This study provides additional evidence for a role for HSL in the development of insulin resistance, from which carriers of the -60G allele, associated here with markers of insulin sensitivity in women, and with lower NEFA levels in men, might be protected.

Induction of melanoma in murine macrophage inflammatory protein 2 transgenic mice heterozygous for inhibitor of kinase/alternate reading frame

The molecular and genetic events that contribute to the genesis and progression of cutaneous malignant melanoma are poorly understood, attributable in large part to the different genetic alterations accompanying tumorigenesis. Inhibitor of kinase 4a (INK4a) is often inactivated in families with hereditary melanoma. Loss of INK4a/alternate reading frame (ARF) in mice is associated with increased incidence of other tumors such as lymphoma and fibrosarcoma. However, the incidence of melanoma in INK4a/ARF-deficient mice is very low. Our previous studies have revealed that the CXC chemokine, CXCL1, is overexpressed in human malignant melanoma cells and is linked to transformation of immortalized murine melanocytes. To study the direct role of CXCL1 on the genesis of primary melanoma lesions, transgenic mouse lines were established that express the murine homologue of CXCL1, murine macrophage inflammatory protein 2 (MIP-2), under the transcriptional control of the tyrosinase promoter/enhancer (Tyr-MIP-2) in the mice that were deficient or not deficient for INK4a/ARF. Strong MIP-2 immunoreactivity was associated with pigmented melanocytes in the hyperproliferative hair follicles in the Tyr-MIP-2 transgenic mice, and the level of MIP-2 expression was similar in both INK4a/ARF heterozygous or wild-type mice. After treatment of mice with 7,12-dimethylbenz(a)anthracene, cutaneous melanomas formed in 12% (17/145) of the Tyr-MIP-2 transgene-positive mice, whereas only 2% (3/146) of the Tyr-MIP-2 transgene-negative mice developed melanoma. When melanocytes cultured from MIP-2 transgenic mice null for INK4a/ARF were transplanted into nude mice, melanoma formation occurred in 83% (10/12) of the cases with a latency period of 3 months. However, no melanoma lesions arose in nude mice injected with INK4a/ARF -/- melanocytes, which did not express the MIP-2 transgene. Our results demonstrate that constitutive expression of MIP-2 in INK4a/ARF-deficient melanocytes facilitates formation of malignant melanoma.

[Transconjunctival approach to the fractures of the orbital floor and infraorbital rim]

OBJECTIVE

To study the surgical approach to the orbital floor and infraorbital rim.

METHOD

15 cases of fractures of the orbital floor and infraorbital rim were treated with the transconjunctival approach.

RESULT

All fractures of the orbital floor and infraorbital rim were repositioned and fixed through transconjunctival approach. Except for 1 case with mild canthal malposition, no other complication was observed.

CONCLUSION

The transconjunctival approach can provide adequate exposure of the infraorbital rim and orbital floor without scar formation in the face.

Uncoupling protein 3 genetic variants in human obesity: the c-55t promoter polymorphism is negatively correlated with body mass index in a UK Caucasian population

OBJECTIVE

To investigate whether genetic variation at the UCP3 locus contributes to human obesity.

SUBJECTS

Ninety-one obese children (BMI>4 standard deviations from age related mean) and 419 Caucasian adults from the Isle of Ely Study.

DESIGN

Single strand conformation polymorphism (SSCP) analysis was used to scan the coding region of the UCP3 gene in 91 severely obese children. A common polymorphism identified in this gene (c-55t) has been shown to associate with lower UCP3 mRNA expression. Polymerase chain reaction-based forced restriction digestion was used to detect this allele in Caucasian adults. Multiple regression analysis was used to determine associations between the c-55t genotype and anthropometric, energetic and biochemical indices relevant to obesity.

MEASUREMENTS

For the obese children, SSCP analysis and sequencing of variants were carried out. For the Isle of Ely Study, c-55t genotype and anthropometric (body mass index, waist-hip ratio, percentage body fat), energetic (dietary fat intake, physical activity index, adjusted metabolic rate, maximum oxygen consumption) and biochemical indices (pre- and post-glucose challenge plasma triglycerides, non-esterified fatty acids, insulin and glucose) were determined.

RESULTS

A previously reported missense mutation (V102I) was detected in a single obese Afro-Carribean child. Twenty-one percent of the genes examined in the Isle of Ely study carried the c-55t promoter variant. Age-adjusted body mass index (BMI) was significantly (P=0.0037) lower in carriers of this variant.

CONCLUSION

Mutations in the coding sequence of UCP3 are unlikely to be a common monogenic cause of severe human obesity. In a Caucasian population the UCP3 c-55t polymorphism is negatively associated with BMI.

Evidence for gene-nutrient interaction at the PPARgamma locus

The importance of the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma) in regulating insulin resistance and blood pressure has been demonstrated in families with loss of function mutations. Gain of function mutations has been associated with severe obesity. However, previous population studies of the common variant Pro12Ala have produced conflicting results. As it is likely that the natural ligands for this receptor may include fatty acids, we hypothesized that the effect of this common variant may be altered by the character of the diet, particularly the ratio of dietary polyunsaturated fat to saturated fat (P:S ratio). We studied 592 nondiabetic participants in an ongoing population-based cohort study who were genotyped for the Pro12Ala polymorphism in the PPAR gamma2 isoform. As the Ala homozygotes were uncommon (2.0%), all analyses were conducted comparing Pro homozygotes (79.1%) to Ala allele carriers. There was no difference in fasting insulin concentration or BMI between Ala allele carriers and Pro homozygotes. The fasting insulin concentration was negatively associated with the P:S ratio (P = 0.0119) after adjustment for age and sex, and a strong interaction was evident between the P:S ratio and the Pro12Ala polymorphism for both BMI (P = 0.0038) and fasting insulin (P = 0.0097). The data suggest that when the dietary P:S ratio is low, the BMI in Ala carriers is greater than that in Pro homozygotes, but when the dietary ratio is high, the opposite is seen. This gene-nutrient interaction emphasizes the difficulty of examining the effect of common polymorphisms in the absence of data on nongenetic exposures, and may explain the heterogeneity of findings in previous studies.

Junctional epidermolysis bullosa associated with congenital localized absence of skin, and pyloric atresia in two newborn siblings

Congenital localized absence of the skin has been observed in various subsets of inherited epidermolysis bullosa (EB). Pyloric atresia is a rare disorder that has been seen in association with EB. Ureterovesical junction obstruction is a condition unique to the association between pyloric atresia and EB. The authors describe 2 premature male siblings with pyloric atresia, congenital localized absence of the skin, urinary obstruction, and EB at birth. Electron microscopic study of the biopsy specimen from the first sibling revealed characteristic findings of EB simplex. However, prenatal diagnosis of the next sibling was made by integrin B4 mutations and the electron microscopic study of the biopsy specimen after delivery confirmed junctional EB (JEB). These cases emphasize this unusual combination of defects and limitations of electron microscopy.

[Clinical analysis of 40 patients who were re-operated after prosthetic augmentation mammaplasty]

OBJECTIVE

To summarize the reasons of complications after prosthetic augmentation mammaplasty and explore the optimal preventive measures and therapy.

METHOD

The reasons for 40 patients who were re-operated on after prosthetic augmentation mammaplasty were analyzed in as many aspects as possible, such as the location of the incision, the type of the prosthesis, etc. Preventive measures and therapy of the complications were also summarized.

RESULTS

Capsular contracture was the most common reason for reoperation. The second was prosthetic rupture and translocation. The main reasons resulting in complications included impertinent indications, poor quality of the prosthesis and an incompetent surgeon.

CONCLUSIONS

The key to reduce the complications is proper selection of good prosthesis, strict indications, better comprehension of the knowledge about prosthetic augmentation mammaplasty and a qualified plastic and aesthetic surgeon for the operation. The inareolar incision is the best choice to remedy the complications.

[The clinical study of tongue flaps repairing after resecting pharyngeal neoplasm and laryngeal neoplasm]

OBJECTIVE

To study the repair methods of the defect after resecting pharyngeal neoplasm and laryngeal neoplasm.

METHODS

Four kinds of tongue flap, such as 1/3 tongue flap, 1/2 tongue base flap, tongue base flap and transverse tongue flap were devised and applied in 15 patients with pharyngeal neoplasm and laryngeal neoplasm.

RESULTS

These tongue flaps were alive in all patients. The wound of 13 patients healed in I stage. Two patients dehiscenced because of infection and healed after treatment. All the patients deglutited well. One-year, 3-year, disease-free survive rate were 92.9% (13/14), 72.7% (8/11) respectively.

CONCLUSION

Tongue flaps are obtained easily, with enough blood flow, adapted to pharyngeal environment, easily alive and low complication in repairing the pharyngeal defect. We think that these tongue flaps should be applied in clinic.

A common apolipoprotein B signal peptide polymorphism modifies the relation between plasma non-esterified fatty acids and triglyceride concentration in men

Insulin and non-esterified fatty acids (NEFA) are important regulators of triglyceride metabolism. The relations between these compounds and the effect of a common 3 amino acid deletion in the apolipoprotein B (ApoB) signal peptide (SP) following an oral glucose challenge have been investigated. The frequency of the shorter SP-24 allele was 32% (95% C.I. 29.5-36.5) in 725 subjects undergoing an oral glucose tolerance test (OGTT). Fasting plasma triglyceride concentration was positively correlated with fasting plasma insulin concentration and negatively with the degree of plasma NEFA suppression following the glucose challenge. Linear regression analysis showed the relation between triglyceride concentration and NEFA suppression, but not the relation between triglyceride concentration and fasting insulin, to be altered by the SP polymorphism in men but not in women. The strength of the association was dependent on the number of SP-24 alleles, with SP-24 homozygotes showing the greatest dependence (men P=0.031, women P=0. 914). It was proposed that the complex regulation of very low density lipoprotein (VLDL) output by NEFA and by insulin may explain, at least in part, the conflicting reports concerning the presence of the ApoB SP polymorphism, fasting serum lipids and ischaemic heart disease (IHD).

[Study on the pharmacologic effect of propolis]

Pharmacologic effects of propolis were investigated in this article. The results suggested that propolis has pharmacologic functions in many aspects. It is a new-type medicine derived from animal in pharmacology and food both. To small mouse, propolis showed the functions of anti-fatigue and endurance to lack of oxygen. To high-blood-lipid-model mouse, it prevented increase of blood-mucus and blood lipid(TC, TG, LDL-C) (P < 0.05-0.01), but there were insignificant changes to red-blood-cell proportion (HCT) and high-density lipoprotein chelesteral (HDC-C). To small immunosuppessive-model mouse, propolis could strengthen macrophagocyte phagocytosis in the abdominal-cavity (P < 0.05), and increase the thymus-index (P < 0.05), but there were insignificant changes to the spleen-index. The LD50 > 7500 mg/kg to small mouse.

The CART gene and human obesity: mutational analysis and population genetics

The cocaine- and amphetamine-regulated transcript (CART) peptide is a recently characterized neuropeptide implicated in the control of appetite. We hypothesized that genetic variation in CART may contribute to human obesity. The entire coding region of CART was determined by nucleotide sequencing in 91 unrelated subjects with severe early-onset obesity. A novel amino acid change, Ser66Thr, was found in 2 probands and in 0 of 100 control subjects but did not cosegregate with obesity in family studies. Two common polymorphisms were found in the 3'-untranslated region (A1475G and deltaA1457). An effect of these polymorphisms on body composition and intermediate phenotypes related to obesity was examined in a large Caucasian population in the U.K. Neither polymorphism showed any significant relationship with obesity; however, men heterozygous for the A1475G variant had significantly lower waist-to-hip ratio (WHR), fasting plasma insulin, and fasting triglycerides. Regression analysis indicated that the effects on insulin and triglycerides were likely to be secondary to the effects on WHR. Thus, we have conducted the first systematic study of the CART gene in human obesity, and although no clear association with obesity was found, the data suggest that genetic variation in the CART locus might influence fat distribution and variables related to syndrome X.