Protection from inflammatory disease in insulin resistance: the role of mannan-binding lectin

AIMS/HYPOTHESIS

Decreased sensing of the innate immune system may lead to chronic activation of the inflammatory cascade. We hypothesised that mannan-binding lectin (MBL) deficiency may confer risk of obesity and insulin resistance.

MATERIALS AND METHODS

We performed a cross-sectional study of MBL protein concentration (n=434) and MBL2 gene mutations (exon 1) (n=759) in association with obesity, markers of inflammation and insulin action (euglycaemic clamp, n=113), and a longitudinal study of MBL protein before and after weight loss in obese patients (n=10). We also studied the effects of MBL in vitro in muscle cells and circulating MBL-A (mouse equivalent of human MBL) in a mouse model.

RESULTS

Among 434 consecutive non-diabetic men, the age-adjusted serum MBL concentration was lower in obese subjects than in lean subjects (median: 959 microg/ml [interquartile range: 116.8-2,044 microg/ml] vs 1,365 [467-2,513] microg/ml; p=0.01) and was accompanied by increased serum inflammatory markers. Insulin action correlated significantly with serum MBL (r=0.49, p<0.0001). Serum MBL concentration increased by a median of 110.2% after weight loss. The change in serum concentration of MBL was positively associated with the increase in insulin sensitivity (r=0.713, p=0.021). At least one MBL2 gene mutation was present in 48.2% of obese vs 39.3% of non-obese subjects (p=0.037). The plasma concentration of MBL-A was lower in insulin-resistant obese ob/ob mice, as was the glucose/insulin ratio. Incubation of rat soleus muscle with human MBL markedly increased fatty acid oxidation.

CONCLUSIONS/INTERPRETATION

These findings suggest that MBL, previously thought only to be involved in inflammation and immune system function, affects metabolic pathways.

Dietary fatty acids and insulin secretion: a population-based study

OBJECTIVE

Few epidemiological studies have examined the relationship of dietary fatty acids, especially MUFA, with the interrelation between insulin secretion and insulin resistance. We assessed the relation of dietary fatty acids with insulin secretion in a free-living population.

DESIGN AND SETTING

This cross-sectional, population-based study was undertaken in Pizarra, a small town in Spain.

SUBJECTS AND METHODS

Anthropometrical data were collected for 1226 persons selected randomly from the municipal census, 538 of whom (randomly chosen) were given a prospective, quantitative, 7-day nutritional questionnaire. The fatty acid composition of the serum phospholipids was used as a biological marker of the type of fat consumed. Beta-cell function (betaCFI) and insulin-resistance index (IRI) were estimated by the Homeostasis Model Assessment.

RESULTS

To determine which factors influence the variability of the betaCFI, we analyzed the variance of the betaCFI according to sex, the presence of carbohydrate metabolism disorders and the different components of the diet, adjusting the models for age, body mass index (BMI) and IRI. The dietary MUFA and polyunsaturated fatty acids (PUFA) contributed to the variability of the betaCFI, whereas only the proportion of serum phospholipid MUFA, but neither the saturated fatty acids nor the PUFA accounted for part of the variability of the betaCFI in a multiple regression analysis.

CONCLUSION

The results of this population-based study corroborate the results of other clinical and experimental studies suggesting a favorable relationship of MUFA with beta-cell insulin secretion.

SPONSORSHIP

Fondo de Investigación Sanitaria, Junta de Andalucía and the Asociación Maimónides.

Recovery of menstrual cycle after therapy for anorexia nervosa

OBJECTIVES

Although the relation between sexual dysfunction, undernourishment and weight loss is clear, amenorrhea sometimes precedes weight loss and may persist despite later weight gain. We therefore studied the variations in anthropometric variables in women with restrictive anorexia nervosa (AN) at the time they recovered their menstrual cycle.

METHOD

We undertook a longitudinal study of 40 women with AN. All were in secondary amenorrhea at the start of the outpatient treatment program. Leptin concentrations were measured during the early follicular phase after the patients had recovered their menstrual cycle and had had two regular cycles. Body composition was measured by multifrequency bioelectric impedentiometry and the lean mass, fat mass and percentage fat were recorded.

RESULTS

The menstrual cycle returned in 25% of the patients with a BMI of 17 or lower, in 50% of the patients with fat percentages of 20% or lower and in 25% with fat percentages of 17% or lower. Over 20% of the patients recovered their menstrual cycle without having leptin figures above 1.85 ng/ml.

DISCUSSION

Prediction of recovery of menstruation in women with AN is difficult, as anthropometric variables alone are not sufficient; other factors have also to be taken into account.

Association between MspI polymorphism of the APO AI gene and Type 2 diabetes mellitus

AIMS

Genes of the Apo AI/CIII/AIV cluster on chromosome 11 have been related to plasma lipid patterns. The close relationship between carbohydrate metabolism and lipid metabolism warrants investigation of the association between this cluster and Type 2 diabetes mellitus. We therefore examined the possible association between polymorphisms of this cluster and Type 2 diabetes mellitus as part of a study of the prevalence of diabetes and the metabolic syndrome in southern Spain.

METHODS

A total of 1224 persons were selected randomly from the town of Pizarra in the province of Malaga, southern Spain. The sample errors for the prevalence of Type 2 diabetes mellitus and the three polymorphisms studied were all < or = 4%. All subjects underwent phenotyping after an oral glucose tolerance test (75 g) (WHO 1998 criteria) and the XmnI and MspI polymorphisms of Apo AI and the SstI polymorphism of Apo CIII were genotyped.

RESULTS

Those subjects with the mutated AA genotype of the MspI polymorphism (-75 G-->A) of Apo AI had a greater risk of impaired glucose tolerance [odds ratio (OR) = 1.95, CI = 1.02-3.8, P = 0.05], Type 2 diabetes mellitus, both known (OR = 7.38, CI = 1.3-39.7, P = 0.02) and unknown (OR = 3.7, CI = 1.4-9.9, P = 0.009). This risk was independent of age, sex, obesity, triglyceride level, HDL cholesterol and pattern of insulin resistance.

CONCLUSIONS

Pending confirmation in prospective studies, the AA genotype of the MspI polymorphism of the Apo AI gene, within the Apo A-I/C-III/A-IV cluster, seems to be a risk factor for Type 2 diabetes mellitus.

The apolipoprotein E genotype predicts postprandial hypertriglyceridemia in patients with the metabolic syndrome

Apolipoprotein E (apo E) is a constituent molecule of the triglyceride-rich lipoproteins and participates in their clearance. Polymorphisms in the apo E gene are associated with increased fasting and postprandial levels of triglycerides. We studied 66 patients with the metabolic syndrome, none of whom had diabetes. Details were recorded for cholesterol, triglycerides, apo AI, apo B, insulin, homeostasis model assessment of insulin resistance, homeostasis model assessment of insulin secretion, uric acid, 24-h uric acid urinary excretion, high-density lipoprotein cholesterol, waist to hip ratio, body mass index, and age. The patients were given a 60-g fat overload (Supracal), and measurements were made at 4 h of cholesterol, triglycerides, high-density lipoprotein cholesterol, apo AI, and apo B. Patients who did not have the E3/3 genotype had an odds ratio of postprandial hypertriglyceridemia of 6.2 (confidence interval, 1.41-16.08; P = 0.01) and an odds ratio of hyperuricemia compared with the E3/3-positive patients of 7.5 (confidence interval, 1.04-39.31; P = 0.02). This study shows that patients with the metabolic syndrome who do not have the E3/3 genotype have a greater risk of hyperuricemia and postprandial hypertriglyceridemia after a fat overload.

Dietary palmitic acid influences LDL-mediated lymphocyte proliferation differently to other mono- and polyunsaturated fatty acids in rats

Recent studies suggest that the biological effects of saturated fatty acids depend on the length of their chain. We compared the effect of diets containing different fatty acids on plasma lipids and lymphocyte proliferation in the presence of lovastatin and with increasing amounts of LDL. Lymphocytes from rats fed with a diet rich in palmitic acid had a greater lymphocyte proliferation capacity than those from rats fed with diets rich in oleic acid, linoleic acid, or fish oil. This effect was maintained when small amounts of polyunsaturatwed fatty acids (PUFA; sunflower oil) were added to the palmitic acid diet. LDL receptor activity, measured by the capacity of lovastatin to revert the inhibition of lymphocyte proliferation with increasing amounts of LDL in the medium, was greater in the rats fed with palmitic acid, and was similar to the other groups when small amounts of PUFA were added. All the groups had similar levels of plasma cholesterol, but the LDL levels were significantly lower in the group fed with palmitic acid plus PUFA. The highest HDL-cholesterol (HDLc) levels were found in the palmitic acid group and the lowest LDL-cholesterol (LDLc)/HDLc ratio in the palmitic acid plus PUFA group. These results suggest that diets rich in palmitic acid do not raise total cholesterol, but reduce LDLc or keep it normal, and raise HDLc levels. This effect may be partly due to an increase in LDL receptor activity. The inclusion of small amounts of PUFA in the diet rich in palmitic acid substantially modified the LDL receptor response in the lymphocytes, suggesting that the proportion of different families of dietary fatty acids may be more important than the individual amount of each in absolute terms to explain their effects on plasma lipids and lipoproteins.

Patterns of insulin resistance in the general population of southeast Spain

The aim of this study was to evaluate patterns of insulin resistance in the general population. The study was cross sectional. Clinical, anthropometric, and lipid measurements were made in 1226 persons aged 18-65 years. An oral glucose tolerance test (OGTT) was performed in 1020 subjects, with insulin levels determined at baseline and after 2 h. The homeostasis model assessment insulin resistance index (HOMA IR) and HOMA beta-cell function were calculated. Compared with subjects with normal glucose tolerance, the groups with abnormal OGTT had different baseline insulinemia, 2 h post OGTT insulinemia, HOMA IR and HOMA beta-cell indices. Serum insulin levels at baseline and 2 h after OGTT showed a characteristic pattern for each category of glucose tolerance, resulting from the different insulin responses. In the subjects with normal glucose tolerance, the pattern of the relationships between both types of serum insulin levels was exactly the same, so that it was possible to determine risk groups according to the ratio of baseline serum insulin/2 h insulin. HOMA IR and HOMA beta-cell were significantly associated with the risk of impaired fasting glucose, previously unknown diabetes mellitus, and known diabetes mellitus. These results support the rationale for introducing preventive measures against insulin resistance in the general population.

[Tic disorders and arousal dysfunction: clinical evaluation of 49 children and adolescents]

AIM

Tourette Syndrome (TS) shows a significant comorbidity with obsessive-compulsive disorders, behavioral problems (i.e. attention-deficit/hyperactivity disorders) and sleep disturbances. Several studies showed that sleep problems are common in TS patients affecting 12% to 62% of patients. Aim of this study was to evaluate the relationships between tics, sleep disorders and behavioral disturbances.

METHODS

Fourty-nine consecutive children and adolescents with tics have been studied by the following procedure: a) the Yale Global Tic Severity Scale (YGTSS) was administered in order to establish the severity of tics; b) the Child Behavior Checklist (CBCL) was used to evaluate behavioural disturbances; c) the Sleep Disturbance Scale for Children (SDSC) was filled out in order to assess the presence of sleep disorders. An age-matched control group was used for comparison.

RESULTS

All patients (either TS or non-TS) showed a higher prevalence of sleep disturbances versus the control group. Sleep-wake transition disorders (SWTD) were the most frequent sleep disturbances found in our sample, followed by disorders of initiating and maintaining sleep (DIMS). These latter sleep disturbances were highly correlated with the severity of tics. Internalization problems, anxiety/depression and attention and thinking problems were very frequent in our sample. Correlation analysis showed a positive relationship between internalization problems and DIMS and also between aggressive behaviour and respiratory disturbances during sleep (RDS).

CONCLUSION

The results obtained seem to confirm the literature reports on the strict relationship between tics and sleep disturbances, mainly SWTD, and further support the hypothesis of a dysfunction of arousal mechanism in TS.

Colour Doppler echocardiography in children with group A streptococcal infection related tic disorders

BACKGROUND & OBJECTIVES

A possible relationship has been suggested between tic disorders and streptococcal infections. To understand the complex relationship between streptococcal infections and neuropsychiatric disorders in children the present study was done on colour Doppler echocardiography of patients with possible post-streptococcal tic disorders.

METHODS

The patients were 23 children (22 males, 1 female) affected by tic disorders, who at the time of the observation presented (or had presented in the past) signs of streptococcal infections temporally related to the onset or recrudescence of tic disorders. Echocardiographic examination and laboratory tests were performed on these children.

RESULTS

In 4 cases a mild mitral insufficiency and in 8 cases a minimal mitral insufficiency was seen, all haemodynamically not significant. Follow up studies (up to 1 yr) showed the consistency and persistence of these findings. Of the 12 patients with echocardiographic abnormalities, 10 displayed very high anti streptolysin O (ASO) titres, 5 showed positive cultures for GAS and 9 had abnormal ESR, even if no significant differences were found in respect to patients with tics and normal echocardiography.

INTERPRETATION & CONCLUSION

With the caution due to the design of study and to low number of patients, our data seem to indicate that the pathophysiology of GAS-infection related tic disorders is similar to that SC, at least in some cases.

Characterisation of group A streptococcal (GAS) isolates from children with tic disorders

BACKGROUND & OBJECTIVES

An association between the onset or recrudescence of some neuropsychiatric disorders in children such as tic disorders and group A streptococcal (GAS) infections has been suggested. No information is available on the characterization of GAS strains associated with such disorders. The present study was undertaken to characterize the GAS strains isolated from children with tic disorders and to determine and correlate the antistreptolysin O (ASO) titre with the presence of GAS.

METHODS

During 1996-2001, 368 children with tic disorders were investigated for possible exposition to streptococcal antigens. All children, at the time of the first visit and during the follow up visits were apparently healthy and showed no clinical evidence of streptococcal infections or post streptococcal sequelae. Blood and throat swab samples were collected and serological and bacteriological tests done. The isolates obtained were investigated for T pattern, M protein and emm type, as well as for the production of protease.

RESULTS

Of the 800 throat swabs studied 100, corresponding to 67 patients, were positive for GAS; 49 children were found positive for GAS only once during the study, 18 had more than one sample positive for different serotypes, 8 were positive twice or more for the same type. ASO titres of these children were, in general, elevated. Five types, namely type M12, 3, 13, 11, 1, accounted for 39 per cent of the isolates, M12 being the most common, but a large number of different types were also found. A large number of isolates (62%) showed an elevated prodution of protease in the casein plate assay.

INTERPRETATION & CONCLUSION

Despite the high level of ASO titres found, the results were not in favour of a particular virulence or invasivity of the isolates. Only a few colonies per sample were found indicating that factors different from the microbial virulence play a role in this type of disease.

Contribution of polymorphisms in the apolipoprotein AI-CIII-AIV cluster to hyperlipidaemia in patients with gout

BACKGROUND

Studies have shown that hyperuricaemia is independently related to the insulin resistance syndrome and that polymorphisms of the apolipoprotein AI-CIII-AIV cluster are also related to insulin resistance.

OBJECTIVE

To study the prevalence of polymorphisms of the apolipoprotein AI-CIII-AIV cluster in persons with gout and to determine whether these polymorphisms contribute to the pathophysiology of gout or to altered lipid concentrations.

METHODS

Plasma cholesterol, triglycerides, uric acid, VLDL, LDL, IDL, and HDL triglycerides, cholesterol, and the renal excretion of uric acid were measured in 68 patients with gout with gout and 165 healthy subjects. Polymorphisms were studied by amplification and RFLP in all subjects, using XmnI and MspI in the apolipoprotein AI gene and SstI in the apolipoprotein CIII gene.

RESULTS

The A allele at position -75 bp in the apolipoprotein AI gene was more common in patients with gout than in controls (p = 0.01). Levels of cholesterol, triglycerides, uric acid, basal glycaemia, and HDL cholesterol were higher in the patients (p<0.001). In the patients there was also an interaction between mutations at the two polymorphic loci studied in the apolipoprotein AI gene (p = 0.04). An absence of the mutation at position -75 bp of the apolipoprotein AI gene resulted in increased plasma triglyceride levels.

CONCLUSIONS

Gouty patients have an altered allelic distribution in the apolipoprotein AI-CIII-AIV cluster, which could lead to changes in levels of lipoproteins. This is not caused by a single mutation but rather by a combination of different mutations.

Periodic dip of lipidperoxidation in humans: a redox signal to synchronize peripheral circadian clocks?

The output generated by the endogenous circadian clock to control circadian functions and temporal organization in metazoans is unknown. Redox state perturbations generated by reactive oxygen species (ROS) and antioxidants are known to influence the expression of a number of genes and signal transduction pathways. Evidence has been recently provided that the reduced redox cofactors NAD and NADP both regulate clock gene activity in the suprachiasmatic nucleus (SCN) and are induced by it. Significant periodic variations of lipidperoxidation in human blood with a dip at 04.00 h have been previously reported. Such variations could be expected to alter the cellular redox state, thus possibly functioning as periodic redox signals from the master clock. To verify the existence of the mentioned variations the serum levels of malondialdehyde (MDA), a marker of lipidperoxidation, were monitored by High-Performance Liquid Chromatography in 39 healthy subjects at 3-h intervals over a 24-h period. Throughout the test period, only biological noise could be detected in all test persons. However, the normalized MDA levels at 03.00 h were significantly lower (p < 0.05 to < 0.00005) in 38 (97%) of the cases and showed a significantly lower standard deviation (p < 0.004) than at any of the other 3-h intervals, indicating a periodic dip of lipidperoxidation (PDL) in diurnal active subjects. We hypothesize that the PDL, on the basis of its time of appearance, its frequency and its potential influence on cellular redox state, represents a periodic systemic redox output of the SCN, in terms of a relatively short and sudden interruption of the daily oxidative noise. According to recent research, it could be the result of redox alterations induced by the SCN activity and at the same time the pathway by which the master clock resets and synchronizes peripheral oscillators to the light/dark cycle. Additionally, the antioxidative function of the pineal gland activity postulated elsewhere could play a part in generating the described phenomenon. The PDL could be useful as a circadian phase marker in research dealing with treatment of jet lag and other sleep disorders.

The elevated prevalence of apolipoprotein E2 in patients with gout is associated with reduced renal excretion of urates

OBJECTIVE

Previous studies have demonstrated that the lower renal excretion of urates in patients with hyperuricaemia is inversely related to plasma very low-density lipoprotein (VLDL) levels, and the different genotypes of the apolipoprotein E gene are related to the plasma levels of lipids. The aim of this study was to determine the prevalence of apolipoprotein E in hyperuricaemic patients and to investigate whether the renal excretion of urates is conditioned by the apoliprotein E genotype.

METHOD

The plasma levels of lipoproteins, cholesterol, triglycerides and uric acid, and the renal excretion of uric acid were studied in 68 patients with gout and in another control group of 50 healthy subjects. Both groups were genotyped for apolipoprotein E by means of an amplification technique and inverse hybridization.

RESULTS

The prevalence of the E2 allele was greater in the patients than in the control group. The levels of cholesterol, triglycerides and uric acid were greater in the patients, whereas the levels of high-density lipoprotein were lower. The patients with the E2 allele had higher levels of triglycerides in VLDL and intermediate-density lipoproteins and a lower renal excretion of urates.

CONCLUSIONS

These results show that the reduced renal excretion of uric acid in patients with gout is mediated by high levels of VLDL and by the high prevalence of the E2 allele of apolipoprotein E.

Autosomal dominant GTP-CH deficiency presenting as a dopa-responsive myoclonus-dystonia syndrome

The authors report a kindred in which GTP-CH deficiency resulted in a myoclonus-dystonia syndrome. The proband, a 17-year-old boy, presented with early-onset myoclonus and later, dystonia and bradykinesia. Blood prolactin was increased and CSF homovanillic acid, 5-hydroxyindoleacetic acid, and biopterin were all reduced. L-Dopa/carbidopa administration resulted in clinical improvement. In the paternal branch, the grandfather and three relatives had myoclonus-dystonia and resting or postural tremor of limbs. The authors found a missense mutation in the exon 6 of GCH-1 gene (K224R).

Dietary fatty acids modify insulin secretion of rat pancreatic islet cells in vitro

The type of dietary fat affects the action of insulin by changes induced in the fatty acid composition of cell membranes. Little is known, however, about the effects of dietary fatty acids on insulin secretion or the possible relation between the fatty acid composition of the membrane phospholipids and insulin secretion. We therefore studied the effects of dietary fatty acids on insulin secretion stimulated by glucose, forskolin and arginine, and on the insulin content of isolated pancreatic islets, as well as on the fatty acid composition of muscle phospholipids, which were used as markers of the diet-induced modifications in the cell membranes. Five groups of rats were fed for one month with diets varying only in their fat composition: olive oil, sunflower oil, soybean oil, fish oil and palmitic acid (16:0) + soybean oil (SAT). The SAT group had higher insulin secretion, independently of the secretagogue used. No significant differences were found in insulin content between the groups. The dietary fatty acids modified the fatty acid composition of the muscle phospholipids, both in endogenously synthesized fatty acids and in those which were unable to be synthesized by the organism. No statistically significant relation was found between insulin secretion and the content of certain fatty acids in the muscle phospholipids.

Increased levels of anti-oxidized low-density lipoprotein antibodies are associated with reduced levels of cholesterol in the general population

Autoantibodies against epitopes of oxidized low-density lipoprotein (LDL), initially shown in human sera, were later related with the atherosclerotic process, although recent studies have questioned this association. Moreover, their association with total cholesterol and plasma LDL, or with the other lipoproteins, is not clear. We studied the relation between the levels of autoantibodies to oxidized LDL and lipoproteins in a population of 400 subjects from the lower Guadalhorce area in Malaga, Spain. Anti-oxidized LDL antibodies were measured by enzyme-linked immunosorbent assay (ELISA), and total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and lipoprotein(a) [Lp(a)] were measured with commercial kits. Subjects who were positive for anti-oxidized LDL antibodies had significantly lower levels of total cholesterol (P <.01) and LDL cholesterol (P <.01). There was a negative correlation between titers of anti-oxidized LDL antibodies and levels of total cholesterol (P =.007) and LDL cholesterol (P =.024). This inverse relation between the levels of anti-oxidized LDL antibodies and the levels of total cholesterol and LDL cholesterol in a large population study, together with the discordances already published, suggests that the relation between anti-oxidized LDL antibodies, arteriosclerosis, and lipids is more complex than initially thought.