Charcot-Marie-Tooth type 4B is caused by mutations in the gene encoding myotubularin-related protein-2

A gene mutated in Charcot-Marie-Tooth disease type 4B (CMT4B), an autosomal recessive demyelinating neuropathy with myelin outfoldings, has been mapped on chromosome 11q22. Using a positional-cloning strategy, we identified in unrelated CMT4B patients mutations occurring in the gene MTMR2, encoding myotubularin-related protein-2, a dual specificity phosphatase (DSP).

Genetic refinement and physical mapping of the CMT4B gene on chromosome 11q22

Charcot-Marie-Tooth disease type 4B (CMT4B) is a demyelinating autosomal recessive motor and sensory neuropathy characterized by focally folded myelin sheaths in the peripheral nerve. We recently mapped the CMT4B gene to a 5-cM interval on chromosome 11q22, using homozygosity mapping and haplotype sharing analysis on a large inbred pedigree. In the present study, we report the construction of a YAC-based transcript map across the 5-cM critical region, including 26 YACs, 35 STSs, and 52 ESTs. Furthermore, using 15 additional physically ordered microsatellite markers from the 11q22 region on the original inbred family, we were able to narrow the critical interval for the gene to 2 Mb, which is now flanked by markers D11S1757 and CHLC-GATA3B05. Finally, after computer analysis of the 33 ESTs assigned to the 2-Mb interval, we demonstrated that 21 different transcripts as well as 3 known genes might represent potential candidates for the disease.

Effects of glucose ingestion on cardiac autonomic nervous system in healthy centenarians: differences with aged subjects

BACKGROUND

Spectral analysis of heart rate variability (HRV) investigates the cardiac autonomic nervous system (ANS) activity. In particular, low frequency/high frequency (LF/HF) is considered an index of cardiac sympatho-vagal balance and is stimulated by glucose ingestion in healthy subjects. No studies have evaluated the effect of glucose ingestion on cardiac ANS in centenarians.

MATERIALS AND METHODS

In 30 healthy centenarians (HC) and 25 aged subjects (AS) power spectral analysis of HRV was investigated during an oral glucose ingestion.

RESULTS

Glucose ingestion rose LF/HF ratio in both groups studied. Such stimulatory effects were restrained to the first 60 min of the study. Independent of age, gender, body mass index (BMI) and fasting plasma norepinephrine and FT3 concentrations, HC had basal total power (1318 +/- 546 vs. 1918 +/- 818 msec2, P < 0.01), lower low frequency (LF) (33 +/- 21 vs. 50 +/- 11 n.u., P < 0. 03), and higher high frequency (HF) (74 +/- 18 vs. 43 +/- 15 n.u., P < 0.05) than AS. Consequently, LF/HF ratio (0.43 +/- 0.07 vs. 0.91 +/- 0.05, P < 0.02) was also lower in HC than in AS. In AS, but not in HC, the baseline LF/HF ratio correlated significantly with BMI (r = 0.48, P < 0.01), waist-hip-ratio (WHR) (r = 0.45, P < 0.02), fasting plasma insulin (r = 0.49, P < 0.01) and norepinephrine (r = 0.57, P < 0.02) concentration. Glucose ingestion was associated with a significant rise in LF/HF ratio in both groups studied but per cent changes in glucose mediated stimulation of LF/HF was lower in HC than in AS. In a control study, water administration did not affect power spectral parameters of HRV.

CONCLUSION

Our study demonstrates that basal- and glucose-stimulated LF/HF, an indirect index of cardiac sympatho-vagal balance, are lower in HC than in AS.

Vitamin E deficiency due to chylomicron retention disease in Marinesco-Sjögren syndrome

We report on 2 brothers (aged 19 and 12 years) with Marinesco-Sjögren syndrome who also had very low serum vitamin E concentrations with an absence of postprandial chylomicrons. The molecular study ruled out ataxia with isolated vitamin E deficiency, abetalipoproteinemia, and hypobetalipoproteinemia. The electron microscopy of the intestinal mucosa was consistent with a chylomicron retention disease. We speculate that both chylomicron retention disease and Marinesco-Sjögren syndrome are related to defects in a gene crucial for the assembly or secretion of the chylomicron particles, leading to very low serum levels of vitamin E.

Effects of insulin on the cardiac autonomic nervous system in insulin-resistant states

The effects of insulin infusion on cardiac autonomic nervous system (ANS) activity were investigated in healthy subjects (n=15) and in patients with various types of insulin-resistance, such as obese subjects (n=20) and those with hypertension (n=15) or type II (non-insulin-dependent) diabetes (n=22). Healthy subjects and patients underwent euglycaemic hyperinsulinaemic glucose clamp, and cardiac ANS and haemodynamic changes were investigated by continuous recording of heart rate variability by the Holter technique and by venous occlusion plethysmography respectively. At baseline, healthy subjects had the highest values for total spectral power and the low-frequency (LF) component, and the lowest value for the high-frequency (HF) component. In the pooled data (n=72), the fasting plasma insulin concentration was correlated with baseline total spectral power (r=-0.37; P<0.001) and the LF/HF ratio (r=-0. 35; P<0.003). Such correlations were still significant (P<0.01 for both) after adjustment for body fat and mean arterial blood pressure. In a multivariate linear stepwise analysis (n=72), a model including body fat, waist/hip ratio, fasting plasma glucose concentration and insulin-mediated glucose uptake explained 47% of the variability of the change in the LF/HF ratio, with body fat (t=-3.11; P<0.01) and insulin-mediated glucose uptake (t=-3.48; P<0. 008) being significantly and independently associated with insulin-mediated changes in the LF/HF ratio. Insulin infusion reduced the total spectral power and increased the LF/HF ratio in healthy subjects, but not in insulin-resistant patients. In conclusion, our study demonstrates that insulin fails to stimulate cardiac ANS activity in insulin-resistant patients, independently of the causes of insulin resistance.

Familial temporal lobe epilepsy autosomal dominant inheritance in a large pedigree from southern Italy

To further elucidate the inheritance pattern and range of phenotypic manifestations of benign familial temporal lobe epilepsy (FTLE), we report a large family recently identified in southern Italy. There were 8 patients (4 men), ranging in age from 31 to 68 years in three generations. One affected patient was deceased at the time of the study. Genealogical study strongly supported autosomal dominant inheritance with incomplete penetrance, as three unaffected individuals transmitted the disease. Clinical anticipation could not be assessed because of the ascertainment method. Male to male transmission occurred. Identifiable antecedents for seizures were present in only two patients, who had a simple febrile convulsion and a closed head trauma, respectively. Migraine was overrepresented in this family. Onset of seizures ranged from 17 to 52 years (mean: 27 years). All patients had weekly simple partial seizures suggestive of temporal origin with vegetative or experiential phenomena. Very rare partial complex seizures occurred in 6/7 patients. One had two generalized nocturnal seizures as well. Two had previously been misdiagnosed as having gastritis or panic attacks, and one had not been diagnosed. Interictal anteromesiotemporal spiking was seen in 5/7 patients, and occurred mostly during NREM sleep. Neurological examination, brain CT or MR scans were normal. Antiepileptic medication always controlled the seizures.

Genetic refinement and physical mapping of the CMT4B gene on chromosome 11q22

Charcot-Marie-Tooth disease type 4B (CMT4B) is a demyelinating autosomal recessive motor and sensory neuropathy characterized by focally folded myelin sheaths in the peripheral nerve. We recently mapped the CMT4B gene to a 5-cM interval on chromosome 11q22, using homozygosity mapping and haplotype sharing analysis on a large inbred pedigree. In the present study, we report the construction of a YAC-based transcript map across the 5-cM critical region, including 26 YACs, 35 STSs, and 52 ESTs. Furthermore, using 15 additional physically ordered microsatellite markers from the 11q22 region on the original inbred family, we were able to narrow the critical interval for the gene to 2 Mb, which is now flanked by markers D11S1757 and CHLC-GATA3B05. Finally, after computer analysis of the 33 ESTs assigned to the 2-Mb interval, we demonstrated that 21 different transcripts as well as 3 known genes might represent potential candidates for the disease.

The dopamine D2 receptor gene is a susceptibility locus for Parkinson's disease

The dopamine D2 receptor (DRD2) gene has been proposed as a candidate gene underlying several psychiatric and neurologic disorders. The aim of the present study was to examine if selected polymorphisms in the DRD2 gene are associated with Parkinson's disease (PD). We determined the allelic frequencies for four polymorphisms located in the DRD2 gene in a sample of 135 patients with PD and 202 normal control subjects. No significant difference was observed in the allelic frequencies between patients with PD and control subjects with regard to the -141C Ins/Del and the Ser311/Cys311 variants. On the contrary, the A1 allele of the TaqIA polymorphism and the B1 allele of the TaqIB polymorphism were more frequent in patients with PD than in control subjects (control subjects: TaqIA A1 = 14.6%, TaqIB B1 = 10.6%; patients with PD: TaqIA A1 = 20.7%, TaqIB B1 = 17.4%). Patients carrying the A1 allele or the B allele had an increased risk of developing PD (TaqIA, odds ratio: 1.71, 95% confidence intervals: 1.08-2.73; TaqIB, odds ratio: 1.83, 95% confidence intervals: 1.12-3.02). The TaqIA and TaqIB polymorphisms were in strong linkage disequilibrium, suggesting that these two polymorphisms convey the same information about the risk of presenting with PD. Genetic variation in the DRD2 gene may influence the risk of developing PD, thus confirming that the DRD2 gene is a susceptibility locus for PD.

Chronic vitamin E administration improves brachial reactivity and increases intracellular magnesium concentration in type II diabetic patients

Vascular disease accounts for the majority of the clinical complications in diabetes mellitus. As an exaggerated oxidative stress degree has been postulated as the link between diabetes mellitus and endothelial function, a possible positive effect of plasma vitamin E (Vit.E) administration on brachial reactivity could be postulated. Our study aims at investigating the possible effect of chronic Vit.E administration on brachial reactivity, oxidative stress indexes, and intracellular magnesium and calcium content in type II diabetic patients free of diabetic complications. Forty adult, type II diabetic patients were enrolled in the study, which was deigned as a double blind, randomized vs. placebo trial. At baseline all patients underwent the following tests: 1) anthropometric and metabolic examinations, 2) evaluation of oxidative stress indexes, 3) intracellular magnesium and calcium measurements, and 4) determination of arterial compliance and distensibility. Then, all patients were randomly assigned to Vit.E treatment at a dose of 600 mg/day (Evion Forte; n = 20) or placebo (n = 20) over 8 weeks. At the end of this treatment period, a complete reevaluation of the patients was made. Vit.E treatment was associated with a significant improvement in the percent change in brachial artery diameter (P<0.03) and oxidative stress indexes (P< 0.005). In the Vit.E group, the percent change in brachial artery diameter correlated positively with the percent change in oxidative stress indexes (oxidized/reduced glutathione, Trolox-equivalent antioxidant capacity, thiobarbituric acid reaction products, lipid peroxides) and intracellular cation content (magnesium and calcium). After adjustment for age, sex, body mass index, and wait/hip ratio, all of these correlations remained significant (P<0.03 for all). Furthermore, adjusting for glycosylated hemoglobin, plasma total cholesterol, and homeostatic model index, brachial artery diameter was still correlated with the percent change in oxidative stress indexes (P<0.04 for all). Nevertheless, the relationship between the percent change in brachial artery diameter and oxidative stress indexes was no longer significant after adjustment for intracellular Mg and Ca2+. In conclusion, our study demonstrates that chronic administration of Vit.E improves brachial artery reactivity in patients with type II diabetes mellitus. Such an effect seems mediated by a reduction in oxidative stress and a regulation of intracellular calcium and magnesium contents.

Apolipoprotein E polymorphisms and Parkinson's disease

The apolipoprotein E (APOE) gene polymorphism has been studied in Parkinson's disease (PD) with conflicting results. Recently, a newly described functional polymorphism in the regulatory region of the APOE gene, (-491 A/T), has been associated with late-onset Alzheimer's disease. We studied the association between these two polymorphisms of the APOE gene with PD in a sample of 126 PD patients and in 119 controls from the same geographic background. Allelic and genotypic frequencies were not different between PD cases and population controls for either the APOE or -491 A/T polymorphism. The age at onset of the disease was not different according to the specific genotypes of the two polymorphisms of the APOE gene.

Apolipoprotein E polymorphisms and the risk of nonlesional temporal lobe epilepsy

PURPOSE

To evaluate whether the inheritance of the apolipoprotein E (ApoE) epsilon4 allele is a risk factor for nonlesional temporal lobe epilepsy (TLE), and to determine whether the newly described -491 A/T ApoE polymorphism may independently affect the risk of nonlesional TLE.

METHODS

The study group consisted of 63 patients (35 women and 28 men; age at onset of epilepsy, 30.6 +/- 19.6 years; mean (+/-SD). All of them had received a diagnosis of nonlesional TLE after a detailed clinical, electroencephalographic, and brain magnetic resonance investigation. The ApoE polymorphisms were determined from blood samples by standard methods. The molecular study also was performed in 220 age- and sex-matched normal individuals.

RESULTS

There were no differences between TLE patients and controls in either allelic or genotypic frequencies of the ApoE and -491A/T polymorphisms. Moreover, no effect of ApoE or -491A/T polymorphisms was found on the age at onset and severity of epilepsy.

CONCLUSIONS

The allelic and genotypic frequencies of ApoE polymorphisms in Italian patients with nonlesional TLE are comparable to control values, indicating that ApoE polymorphisms are not a significant genetic risk factor for the occurrence of nonlesional TLE.

Baseline heart rate variability in healthy centenarians: differences compared with aged subjects (>75 years old)

Healthy centenarians have better anthropometric, endocrine, metabolic and immunological parameters than aged subjects (>75 years old). Heart rate variability (HRV) has been demonstrated to be a good index of the cardiac autonomic nervous system. It is not known whether there are any differences in cardiac autonomic nervous system activity between aged subjects and healthy centenarians. It is possible that differences in cardiac autonomic nervous system activity could represent one of a cluster of factors explaining the extreme survival of centenarians. Thus we aimed to answer the following question: is there any difference in baseline HRV parameters between aged subjects and healthy centenarians? Therefore power spectral analysis of HRV at baseline was investigated in 25 aged subjects (age > or = 75 years) and 30 healthy centenarians (age > or = 0 years). Anthropometric measurements were made in all subjects, fasting blood samples were drawn for metabolite determinations, and HRV was determined. Independent of age, gender, body mass index and fasting plasma noradrenaline and free 3,3',5-tri-iodothyronine concentrations, healthy centenarians had lower basal values for total power (1318+/-546 compared with 1918+/-818 ms(2); P<0.01) and the low-frequency component (33+/-21 compared with 50+/-11 normalized units; P<0.03) and a higher value for the high-frequency component (77+/-15 compared with 61+/-18 normalized units; P<0.05) than aged subjects. Consequently, the low-frequency/high-frequency ratio (0.43+/-0.07 compared with 0.91+/-0.05; P<0.02) was also lower in the healthy centenarians than in the aged subjects. Our study demonstrates that the basal low-frequency/high-frequency ratio, an indirect index of cardiac sympathovagal balance, is lower in healthy centenarians than in aged subjects.

A hypofibrinolytic state in overweight patients with cerebral venous thrombosis and isolated intracranial hypertension

Evidence suggests that isolated intracranial hypertension (iIH) is often associated with cerebral venous thrombosis (CVT). In eight patients referred to our Institution for iIH who were later shown to harbor CVT we have performed a comprehensive coagulation work-up, including genetic tests for inherited predisposition to thrombophilia, to clarify the etiology of sinus venous thrombosis. All subjects were women. All but one were overweight. There were high plasma concentrations of D dimer, thrombin-anti-thrombin complexes or prothrombin fragments 1 and 2, further supporting the neuroimaging diagnosis of CVT. Importantly, seven of eight cases had a raised level of plasminogen activator inhibitor 1, a well known inhibitor of fibrinolysis related to obesity. Tissue plasminogen activator levels were elevated accordingly. Factor V gene mutation was present in one subject, and the 20,210 prothrombin gene mutation was found in another individual. Three patients had elevated plasmatic levels of homocysteine. In conclusion, the present study provides solid evidence that impaired fibrinolysis probably related to overweight, acting in concert with other prothrombotic abnormalities, is involved in the pathogenesis of CVT presenting as iIH.

APOE and risk of cognitive impairment in multiple sclerosis

OBJECTIVES

The APOE gene polymorphism and the -491 A/T polymorphism in its regulatory region have been associated with an increased risk for developing Alzheimer's disease. We examined these polymorphisms in multiple sclerosis (MS) patients, to determine if a genetic predisposition may explain the risk for developing cognitive decline in MS.

MATERIAL AND METHODS

Eighty-nine relapsing-remitting and secondary progressive MS patients underwent to a full neuropsychological battery as well as to determination of APOE and -491 A/T polymorphisms. Genetic analysis was also performed in 107 population controls.

RESULTS

The APOE polymorphism was not associated with the risk of cognitive impairment in MS patients. The AA genotype of the -491 A/T polymorphism in the APOE regulatory region was more frequent in cognitively impaired than in cognitively preserved MS subjects.

CONCLUSION

The AA homozygous state of the -491 A/T polymorphism of the APOE regulatory region is associated with cognitive impairment in patients with MS.

Low plasma insulin-like growth factor-1 concentrations predict worsening of insulin-mediated glucose uptake in older people

OBJECTIVE

The relationship among insulin action, advancing age, and insulin like growth factor-1 (IGF-1) is poorly understood. To gain further insight, the predictive role that low plasma IGF-1 concentration may have on insulin- mediated glucose uptake in older persons was investigated.

DESIGN

The study was designed as a longitudinal, observational trial.

PARTICIPANTS

Fifty-eight healthy aged (73.1+/-9.4 years) subjects (31 males/27 females) were followed up for 12 months.

MEASUREMENTS

At baseline and at the end of the follow-up, insulin-mediated glucose uptake was assessed by euglycemic glucose clamp and plasma total IGF-1 and IGF-binding protein 3 (IGF-BP-3) in each subject, and concentrations were determined.

RESULTS

At baseline, plasma IGF-1 concentrations correlated with whole body glucose uptake (WBGD) (r = 0.39, P < .003), insulin-stimulated glucose oxidation (GOX) (r = 0.35, P < .009), and non-oxidative glucose metabolism (r = 0.37, P < .007). Such correlations were also independent of age, sex, body fat, and waist/hip ratio. Fasting plasma total IGF-1 concentrations (84+/-56 vs 63+/-44 microg/L, P < .040), plasma IGF-1/IGF-BP3 molar ratio (0.13+/-0.05 vs 0.10+/-0.03 P < .050), and WBGD (34.8+/-5.0 vs 23.1+/-4.6 micromol/kg x min, P < .010) were more elevated at baseline than at the end of the follow-up. Low baseline fasting plasma IGF-1 concentration (RR = 1.5, 95%CI = 1.3-1.7) and plasma IGF-1/IGFBP-3 molar ratio (RR = 1.4, 95% CI = 1.3-1.8) predicted a decline in WBGD. The predictive role of plasma IGF-1 on age-related decline in WBGD was independent of age, sex, body fat, waist/hip ratio, and degree of physical activity (model 1), or of fasting plasma free fatty acid and triglyceride concentrations, LDL/HDL ratio, and basal adjusted respiratory quotient (model 2). Finally, low plasma IGF-1 concentration predicts a decline in WBGD independent of body fat, free fatty acids, waist/hip ratio, and basal adjusted respiratory quotient (model 3).

CONCLUSION

Our study demonstrates that fasting plasma IGF-1 concentration may have a modulatory role on insulin action in older people. This finding might prompt an evaluation of the direct effect of IGF-1 administration on insulin sensitivity in older adults.

Dopamine D2 receptor gene polymorphism and the risk of levodopa-induced dyskinesias in PD

OBJECTIVE

To investigate whether polymorphisms in the genes for dopamine receptors D1 and D2 are associated with the risk of developing peak-dose dyskinesias in PD.

BACKGROUND

Peak-dose dyskinesias are the most common side effects of levodopa therapy for PD. The identified predictors may only partially account for the risk of developing peak-dose dyskinesias because a substantial proportion of patients never develop peak-dose dyskinesias. Genetic factors could play a role in determining the occurrence of peak-dose dyskinesias.

METHODS

A case-control study of 136 subjects with sporadic PD and 224 population control subjects. We studied three polymorphisms involving the dopamine receptor D1 gene and one intronic short tandem repeat polymorphism of the dopamine receptor D2 gene.

RESULTS

The polymorphisms of the dopamine receptor D1 gene were not associated with the risk of developing PD or peak-dose dyskinesias. The 15 allele of the polymorphism of the dopamine receptor D2 gene was more frequent in parkinsonian subjects than in control subjects. More important, the frequency of both the 13 allele and the 14 allele of the dopamine receptor D2 gene polymorphism was higher in nondyskinetic than in the dyskinetic PD subjects. The risk reduction of developing peak-dose dyskinesias for PD subjects carrying at least 1 of the 13 or 14 alleles was 72% with respect to the PD subjects who did not carry these alleles.

CONCLUSIONS

Certain alleles of the short tandem repeat polymorphism of the dopamine receptor D2 gene reduce the risk of developing peak-dose dyskinesias and could contribute to varying susceptibility to develop peak-dose dyskinesias during levodopa therapy.

Autosomal recessive hereditary motor and sensory neuropathy with focally folded myelin sheaths (CMT4B)

Hereditary motor and sensory neuropathy with focally folded myelin sheaths, or Charcot-Marie-Tooth neuropathy type 4B (CMT4B), is a distinct clinical and genetic entity belonging to the heterogeneous group of autosomal recessive demyelinating neuropathies. We first described a large inbred pedigree with 10 patients affected by CMT4B, which enabled us to uncover the genetic findings, clinical spectrum, and natural history of such a disorder. The clinical picture was characterized by infantile onset with progressive symmetric distal and proximal muscular weakness. Using homozygosity mapping and haplotype sharing analysis, we found evidence of linkage of chromosome 11q23. We then identified a second unrelated family in which two individuals were affected with CMT4B. Although the clinical findings were similar to those previously reported, we excluded the disease locus segregating in this smaller pedigree from the 11q23 region. We thus provided evidence for a second locus causing the CMT4B phenotype. All these findings indicate that CMT4B seems to be phenotypically quite homogeneous, but is genetically heterogeneous.

Emotion-induced myoclonic absence-like seizures in a patient with inv-dup(15) syndrome: a clinical, EEG, and molecular genetic study

We have described a clinical EEG and molecular genetic study of a 9-year-old boy with inv-dup(15) syndrome in whom seizures were induced by emotionally gratifying stimuli. The reflex seizures began 5-20 s after the onset of repeated cheek-kissing from his mother or after viewing of pleasant or funny events. They were characterized by bilateral discharges involving mainly the temporal regions and evolving into myoclonic absence-like seizures. Nonemotional stimuli, such as a pinch, sucking or rubbing his cheeks, or the sound of the kiss alone, failed to provoke seizures. The seizures were resistant to antiepileptic (AED) treatments. Molecular genetic investigations revealed a correct methylation pattern of the chromosomes 15, and three copies (two maternal and one paternal) of the segment 15q11-q13, including the GABRb3 gene. We hypothesize that an overexpression of cerebral gamma-aminobutyric acid (GABA)-mediated inhibition accounts for the severe epilepsy that we observed in this patient.

Pharmacodynamics of the long-duration response to levodopa in PD

OBJECTIVE

To determine the latency, magnitude, and duration of the long-duration response (LDR) to levodopa in PD in relationship to the administration of levodopa at different interdose intervals.

METHODS

In six patients with PD, two different 15-day treatment regimens were used in which the drug was administered with interdose intervals of 24 or 8 hours.

RESULTS

The LDR built up within a few days with either regimen, but a faster rate of administering levodopa shortened the latency to the appearance of a sustained LDR. Once a sustained response had been reached, the magnitude of the LDR showed a stable ceiling effect that was independent of the levodopa schedule. After discontinuation of treatment, the decay of the LDR was similar for both regimens.

CONCLUSIONS

The system underlying the LDR to levodopa may be completely saturated when a sustained response has been fully developed. The intervals between doses of levodopa shorter than the interval effective to reach a sustained LDR should not be used in the clinical management of patients with PD because the antiparkinsonian benefit deriving from the LDR is already maximal and briefer intervals do not provide a greater benefit.

Effects of different insulin infusion rates on heart rate variability in lean and obese subjects

The low-frequency to high-frequency ratio (LF/HF ratio) is an index of cardiac sympathovagal balance. We hypothesized that insulin might also stimulate the LF/HF ratio. Thus, 15 lean and 15 obese subjects were studied. Each subject underwent sequential hyperinsulinemic clamps (insulin infusion rate 0.50, 1, and 2 mU/kg x min) while the heart rate was recorded by the Holter technique continuously. Indirect calorimetry allowed determination of the respiratory quotient (Rq) and substrate oxidation. The leg blood flow (LBF), leg vascular resistance (LVR), and plasma norepinephrine concentration were also measured. In seven lean subjects, hyperinsulinemic clamps were repeated along with propranolol infusion (0.1 mg x kg(-1) as an intravenous bolus dose followed by continuous intravenous infusion of 0.5 mg x kg(-1) x min(-1) throughout the study). Lean subjects had better insulin action than obese subjects. Insulin infusion was associated with an increase of the deltaLF/HF ratio in both lean (P < .001 for time-dependent changes) and obese (P < .02 for time-dependent changes) subjects; however, the extent of insulin-mediated stimulation of the LF/HF ratio was greater in lean versus obese subjects. Insulin infusion did not significantly affect HF values in both groups. Independently of gender, body fat, changes in the plasma norepinephrine concentration, LBF, and LVR, the deltaLF/HF ratio at the end of the fastest insulin infusion (0.8 +/- 0.2 v 0.3 +/- 0.2, P < .04) was still greater in lean versus obese subjects. The deltaLF/HF ratio was also more stimulated during insulin versus insulin + propranolol infusion in lean subjects. In conclusion, insulin stimulates the LF/HF ratio in both lean and obese subjects and thus produces a shift in the cardiac autonomic nervous system activity toward sympathetic predominance.

Prognostic importance of insulin-mediated glucose uptake in aged patients with congestive heart failure secondary to mitral and/or aortic valve disease

Previous studies have demonstrated that insulin resistance is a common feature of congestive heart failure (CHF), but the clinical significance of such insulin resistance is still debated. We tested the hypothesis that insulin-mediated glucose uptake (IMGU) is a prognostic factor in CHF in aged patients. For this purpose 174 aged patients with CHF participated in a cross-sectional and a longitudinal study of 24 months' duration. In this latter study survival analysis was calculated comparing subjects at the first and second tertile of IMGU with those at third tertile. All subjects underwent anthropometric (body mass index, waist/hip ratio), cardiovascular (arterial blood pressure, 24-hour Holter monitoring, peak VO2, left ventricular ejection fraction, echocardiography), and metabolic (determination of fasting plasma glucose, insulin, catecholamine, free fatty acids, tumor necrosis factor-alpha concentrations, and assessment of IMGU by euglycemic hyperinsulinemic glucose clamp) investigations. In the cross-sectional study, IMGU correlated with age (r = -0.33, p <0.001), body mass index (r = -0.46 p <0.001), ventricular premature complexes (r = -0.78, p <0.001), left ventricular ejection fraction (r = -0.15, p <0.05), fasting plasma norepinephrine (r = -0.75, p <0.001), tumor necrosis factor-alpha (r = -0.45, p <0.001), free fatty acids (r = -0.54, p <0.001), and peak VO2 (r = 0.67, p <0.001). In the longitudinal study patients at the first and second tertile of IMGU had a lower probability of survival than patients at the third tertile (p <0.03). Cox regression analysis showed IMGU to be a prognostic factor independent of fasting plasma norepinephrine, tumor necrosis factor-alpha, free fatty acid concentration, New York Heart Association class, peak VO2, and left ventricle ejection fraction (relative risk 1.1, 95% confidence intervals 1.0 to 2.1). In conclusion, our study demonstrates that insulin resistance is a common feature of CHF most likely due to elevated plasma norepinephrine and tumor necrosis factor-alpha concentrations, and that IMGU is an independent prognostic factor in CHF.

Idiopathic generalized epilepsies with versive or circling seizures

OBJECTIVES

To describe the electroclinical features of the idiopathic generalized epilepsies (IGEs) with versive or circling seizures.

METHODS

Sixteen patients with versive or circling seizures and interictal electroclinical features of IGE were studied. Patients with insufficient clinical or imaging data, with a follow-up period less than 1 year or with partial seizures in addition to the versive or circling ones were excluded from the study. All patients underwent full interictal clinical and neurophysiological studies. The EEG patterns of 13 versive or circling seizures from 4 patients were also analyzed.

RESULTS

A specific IGE syndrome was recognized in 9 out of the 16 patients (56%). More specific, 1 patient had childhood absence epilepsy (CAE), 4 had juvenile absence epilepsy (JAE), and 4 had juvenile myoclonic epilepsy (JME). No specific IGE syndrome was recognizable in the remaining 7 patients (44%). These 7 patients had a juvenile epileptic syndrome (mean age at onset of seizures was 15.7 years) characterized by versive or circling seizures followed or not by generalized tonic-clonic fits. Three main EEG patterns were identified during versive or circling seizures: 1) generalized spike-and-wave discharges at 3-4 cps; 2) generalized polyspike-and-wave discharges at 1 to 2.5 cps beginning with generalized fast activity at 12-14 cps, and 3) generalized spike-and-wave discharges at 3-4 cps intermingled with fast activity at 12-14 cps. Most patients had good response to treatment on a single drug regimen (mainly valproic acid).

CONCLUSIONS

Versive or circling seizures may occur in the context of an IGE. Although many individuals share the features of different IGE syndromes including CAE, JAE and JME, a consistent number of patients, who show circling or versive seizures solely, remain without a specific syndromic diagnosis. When occurring in the context of IGE, circling or versive seizures do not worsen the prognosis.

Hyperekplexia in a patient with a brainstem vascular anomaly

OBJECTIVES

To describe a patient with a clinical picture suggestive of idiopathic hyperekplexia (IH), who was later found to harbour a subtle brainstem vascular anomaly.

PATIENT

A 35-year-old man, 4 years earlier, developed sudden jumping and falling in response to unexpected sensory stimuli.

RESULTS

Neurological examination was normal. Electromyography showed an excessively large and non-habituating motor startle response. There were no mutations of the alpha1 subunit of the inhibitory glycine receptor which cause hereditary hyperekplexia. Although all these findings were consistent with a diagnosis of IH, a blink reflex study showed an enhanced recovery curve suggestive of a brainstem lesion. A detailed MRI study revealed a subtle vascular anomaly involving the lower brainstem.

CONCLUSION

This is the first report of sporadic hyperekplexia related to a brainstem vascular anomaly. Subtle damage to the brainstem should always be excluded in patients with sporadic hyperekplexia, regardless of the coexistence of additional clear-cut neurological symptoms.