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Biomedical subjects

G Menzinger

Publications and source records attributed to G Menzinger.

At least 37 records · Page 2Linked to original sources
PubMed1997

Contribution of central neuropathy to postural instability in IDDM patients with peripheral neuropathy.

OBJECTIVE: To evaluate the contribution of central neuropathy on postural impairment observed in diabetic patients with peripheral neuropathy. RESEARCH DESIGN AND METHODS: Central sensory and motor nervous propagation, nerve conduction velocity, and static posturography were assessed in the following age-matched subjects: 7 IDDM patients with peripheral neuropathy (group DN), 18 IDDM patients without peripheral neuropathy (group D), and 31 control subjects (group C). Somatosensory-evoked potentials (SEPs) during tibial nerve stimulation were recorded, and the spine-to-scalp sensory central conduction time (SCCT) was evaluated. Motor-evoked potentials (MEPs) were recorded from leg muscles during magnetic transcranial brain stimulation, and the scalp-to-spine motor central conduction time (MCCT) was evaluated. The following posturographic parameters were calculated from the statokinesigram: trace length, trace surface, velocity of body sway with its standard deviation, and VFY (a parameter derived from the velocity variance and the anteroposterior mean position of the body). RESULTS: SCCT was significantly higher in the DN group than in the C and D groups (P < 0.001). MCCT was similar in all groups. Posturographic parameters were all significantly impaired in the DN group (P < 0.01). While posturographic parameters showed a direct relationship with some parameters of peripheral nerve conduction, no correlations were observed with SEP and MEP central conduction time. These results were also confirmed by logistic regression, which indicates peripheral neuropathy as the only implicating factor in postural instability (odds ratio 0.22, 95% CI 0.07-0.75) after data reduction by means of factor analysis. CONCLUSIONS: Although diabetic patients with peripheral neuropathy show a delay in central sensory conduction, postural instability may be fully explained by the presence of peripheral neuropathy.

Adult↗
PubMed1997

Autonomic neuropathy: clinical and instrumental findings.

The development of sensitive techniques evaluating functions under autonomic control has allowed the early detection of widespread abnormalities in diabetes mellitus. However, despite a high frequency of functional abnormalities, an overt clinical syndrome develops slowly and is quite rare. Characteristic clinical features, more recent methods for evaluating autonomic function, diagnostic procedures, and main instrumental findings in a diabetic population are reported. Emphasis is given to more promising techniques evaluating autonomic control of the cardiovascular system, such as myocardial scintigraphy and assessment of 24-h blood pressure and heart rate variability. The clinical meaning of the number of functional abnormalities observed in diabetic patients is considered. While the role of autonomic neuropathy in the pathogenesis of gastrointestinal motor disorders, hypoglycaemia unawareness or diabetic impotence needs to be revised, the importance of autonomic-related sweating and blood flow abnormalities in the pathogenesis of diabetic foot lesions is now better documented. Moreover, growing evidence of the importance of autonomic control of cardiovascular system, together with cardiovascular dysfunction linked to diabetic autonomic neuropathy, supports the hypothesis of a possible role of autonomic neuropathy in the increased cardiovascular morbidity and mortality observed in diabetic patients.

Cardiovascular Diseases↗
PubMed1996

Twenty-four-hour pattern of blood pressure and spectral analysis of heart rate variability in diabetic patients with various degrees of autonomic neuropathy. Comparison to standard cardiovascular tests.

We performed four cardiovascular tests of autonomic function (deep breathing, lying to standing, Valsalva manoeuvre, postural hypotension) and simultaneous 24h recordings of blood pressure (BP) and ECG in 35 normotensive diabetic subjects. Autoregressive power spectrum analysis of RR interval variability was applied to 24h ECG recordings to obtain for day and night periods power of low- (0.03-0.15 Hz, LF) and high-frequency (0.18- 0.40 Hz, HF) components, relative markers of sympathetic and vagal activity respectively, and their ratio (LF/HF), assumed as index of sympathovagal balance. Eighteen patients showed normal cardiovascular tests, 6 patients one abnormal heart rate test, 5 patients two abnormal heart rate tests, and 6 patients also abnormal postural hypotension test. In diabetic patients with increasing degree of autonomic neuropathy, there was a progressive reduction of day-night change in systolic BP (p < 0.01), of LF during the day (p < 0.01), of HF during the night (p < 0.04), of day-night change in HF (p < 0.02), and of day-night change in HF/LF (p < 0.03). Day-night change in systolic BP was related to postural hypotension (p < 0.001) and to deep breathing (p < 0.01). Day LF was related to lying to standing (p < 0.001), to postural hypotension (p < 0.005) and to deep breathing (p < 0.007). Night HF was related to deep breathing (p < 0.0002) and to lying to standing (p < 0.02). Day-night change in HF/LF was slightly related to deep breathing, lying to standing, and to postural hypotension (p < 0.04). In a multiple regression analysis including age, diabetes duration, and cardiovascular tests as independent variables, day-night change in BP and day LF were only related to postural hypotension, whereas night HF was related to deep breathing. In conclusion, in diabetic patients with increasing autonomic damage, there is a progressive impairment of nocturnal fall of BP and of sympathetic activity during the day, blunted nocturnal increase of vagal activity and lower circadian variation in sympathovagal balance. The significant but not very close correlation of day-night pattern of BP and sympathovagal activity to standard cardiovascular reflex tests, supports the independent usefulness of 24h BP monitoring and spectral analysis of heart rate variability in diabetic neuropathy.

Adult↗
PubMed1996

Effects of beta-adrenergic blockade on insulin-mediated glucose disposal in hypertensive and normotensive rats.

OBJECTIVE: To evaluate the impact of beta-adrenergic blockade in spontaneously hypertensive rats (SHR) and in their normotensive controls, Wistar-Kyoto (WKY) rats, on whole-body glucose disposal under metabolic steady state conditions, in unrestrained and conscious animals. METHOD: SHR (n = 13) and WKY rats (n = 12) underwent a 240 min insulinaemic clamp study with or without a super-infusion (120th to 240th minutes; second step) of propranolol. RESULTS: From 0 to 120 min (the first step) SHR showed significantly increased glucose uptake, muscle glycogen synthesis and glycogen synthase activity compared with WKY rats. When propranolol was superinfused, glucose uptake and muscle glycogen synthesis in SHR returned to levels similar to those observed in WKY rats during the first step. No significant differences were found for whole-body glycolysis in SHR and WKY in the first and second steps. CONCLUSION: Hypertensive rats display an increased insulin sensitivity compared with controls. Beta-Blockade is associated with a reduction in overall glucose metabolism in SHR, but not in WKY rats.

Adrenergic beta-Antagonists↗
PubMed1996

Postural rearrangement in IDDM patients with peripheral neuropathy.

OBJECTIVE: To evaluate the influence of diabetic peripheral neuropathy on postural strategy. RESEARCH DESIGN AND METHODS: Static posturography and nerve conduction velocity were performed in the following age-matched subjects: 10 IDDM patients with peripheral neuropathy, 23 IDDM patients without peripheral neuropathy, and 21 control subjects. All subjects with signs or symptoms of postural instability were excluded from the study. The following posturographic parameters were drawn: 1) velocity of body sway, expressed as mean velocity and average of the SDs, 2) VFY, the parameter derived from the velocity variance and the anteroposterior mean position of the body (this parameter monitors the postural strategy pursued by the subject), and 3) fast Fourier transformation on the x (FFTX) and y (FFTY) planes, spectral analysis of the frequencies of body oscillation on frontal (x) and anteroposterior (y) planes. RESULTS: Mean velocity and its SD were higher in IDDM patients with peripheral neuropathy than in control subjects and IDDM patients without peripheral neuropathy (P < 0.001). VFY was increased in IDDM patients with peripheral neuropathy versus control subjects and IDDM patients without peripheral neuropathy (P < 0.01). A direct relationship was found between parameters of posturography and some parameters of nerve conduction tests. CONCLUSIONS: Diabetic patients with peripheral neuropathy demonstrate a shift from physiological ankle control to hip postural control as monitored by specific posturography analysis.

Adult↗
PubMed1995

Electrophysiological assessment of visual function in newly-diagnosed IDDM patients.

Electrophysiological tests (electroretinogram, oscillatory potentials, visual evoked potentials, in the basal condition and after photostress) reveal an abnormal function of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess whether electrophysiological abnormalities in visual function exist in newly-diagnosed diabetic patients free of any fluorangiographic signs of retinopathy. Ten control subjects (age 28.7 +/- 2.44 years) and then IDDM patients (age 25.2 +/- 6.78 years; disease duration 5.3 +/- 3.5 months) in stable metabolic control (HbA1C 7.5 +/- 1.1%) were evaluated. Flash-electroretinograms and oscillatory potentials were similar in both groups. Visual evoked potentials (VEP) recorded under basal conditions showed that P100 latency was significantly increased in the diabetic patients compared to control subjects (p < 0.01), while N75-P100 amplitude was similar in both groups. The recovery time of VEP after photostress was equivalent in diabetic patients and control subjects. The impaired basal VEPs suggest an early involvement of the nervous conduction in the optic nerve. However, the preserved flash-electroretinogram and the normal recovery time after photostress indicate that a short disease duration does not induce physiopathological changes in the outer retinal layers or in the macular function.

Adult↗
PubMed1995

Glycogen synthase activity in two rat models of hypertension.

Several studies on both humans and animal models have reported a pathogenetic relationship among hyperinsulinism, insulin resistance, and hypertension. We have previously evaluated whole body glucose disposal and insulin sensitivity in different models of hypertensive rats, showing an increase rather than an impairment of glucose metabolism, which in turn was due to an improved ability of insulin to channel the absorbed glucose towards the nonoxidative disposal. Aiming to confirm our previous findings we performed the direct assay of skeletal muscle glycogen synthase on tissue samples from the previous clamp studies, as a rate limiting step enzyme of glycogen synthesis, under conditions of physiologic hyperinsulinemia and euglycemia. Glycogen synthase was assayed on samples from rectus muscle tissues of spontaneously hypertensive rats and high sodium, one kidney, one figure-8 hypertensive rats. Compared to controls, our data show an increased activity of glycogen synthase in the hypertensive animals, which is consistent with the increased glycogen synthesis previously reported. In conclusion, under our experimental conditions, hypertension and chronic hyperadrenergism are associated with an increased ability of insulin to stimulate glucose uptake and disposal. These latter effects are mainly due to an increase in nonoxidative disposal and glycogen synthase activity.

Animals↗
PubMed1995

Pneumoconiosis and systemic sclerosis following 10 years of exposure to polyvinyl chloride dust.

The case history is presented of a 58 year old man who was exposed to thermoplastic dusts, mainly polyvinyl chloride (PVC), for 10 years. Radiography and high resolution computed tomographic scans of the lungs suggested both pneumoconiotic and scleroderma-like lesions. Transbronchial biopsy revealed foreign body granulomas with macrophages laden with birefringent inclusions which ultrastructurally resembled PVC dust. Biopsy samples of thickened skin showed histological evidence of extensive fibrosis. During follow up Raynaud's phenomenon and oesophageal involvement developed. The antinuclear antibody titre was 1:640, and the Sc1-70 subset was positive. It is concluded that exposure to PVC dust may cause pneumoconiosis and secondary systemic sclerosis.

Chemical Industry↗
PubMed1995

Effects of insulin on cholesterol synthesis in type II diabetes patients.

OBJECTIVE: To evaluate the effects of intensive insulin therapy and subsequent optimized metabolic control on daily urinary mevalonic acid (MVA) excretion, an index of whole-body cholesterol synthesis, and the acute effects of insulin on plasma MVA concentrations in type II diabetes. RESEARCH DESIGN AND METHODS: Ten (five men and five postmenopausal women) nonobese, normolipidemic (total cholesterol < 6.2 mmol/l, triglycerides < 2.82 mmol/l), type II diabetic patients in poor metabolic control (HbA1c > 10%, fasting plasma glucose > 11 mmol/l) and receiving sulfonylurea treatment were selected. The 24-h urinary MVA excretion and plasma lipid values were determined before and after intensive insulin therapy. The acute effects of insulin on plasma MVA concentrations were also evaluated during a 3-h euglycemic hyperinsulinemic clamp study. RESULTS: Urinary MVA excretion rates (mumol/24h) were 1.82 +/- 0.21 in control subjects and 2.49 +/- 0.35 (P < 0.01 vs. control subjects) and 1.78 +/- 0.28 in patients before and after intensive insulin therapy, respectively. Total cholesterol, low-density-lipoprotein (LDL) cholesterol, and triglycerides decreased by 9, 8, and 12%, respectively, after blood glucose optimization. Acute insulin infusion during the euglycemic clamp studies reduced mean plasma MVA concentrations at 120 and 180 min by 29 and 38%, respectively (P < 0.01 for both vs. baseline). CONCLUSIONS: Our study demonstrates that in nonobese, normolipidemic, type II diabetic patients under poor metabolic control, an increased cholesterol synthesis is normalized by insulin therapy. Hyperinsulinemia in the presence of euglycemia acutely decreases the circulating levels of MVA, the immediate product of hydroxymethylglutaryl-CoA reductase activity and an index of whole-body cholesterol synthesis.

Apolipoprotein A-I↗
PubMed1995

Manufactured shoes in the prevention of diabetic foot ulcers.

OBJECTIVE: To evaluate the efficacy of manufactured shoes specially designed for diabetic patients (Podiabetes by Buratto Italy) to prevent relapses of foot ulcerations. RESEARCH DESIGN AND METHODS: A prospective multicenter randomized follow-up study of patients with previous foot ulcerations was conducted. Patients were alternatively assigned to wear either their own shoes (control group, C; n = 36) or therapeutic shoes (Podiabetes group, P; n = 33). The number of ulcer relapses was recorded during 1-year follow-up. RESULTS: Both C and P groups had similar risk factors for foot ulceration (i.e., previous foot ulceration, mean vibratory perception threshold > 25 mV). After 1 year, the foot ulcer relapses were significantly lower in P than in C (27.7 vs. 58.3%; P = 0.009; odds ratio 0.26 [0.2-1.54]). In a multiple regression analysis, the use of therapeutic shoes was negatively associated with foot ulcer relapses (coefficient of variation = -0.315; 95% confidence interval = -0.54 to -0.08; P = 0.009). CONCLUSIONS: The use of specially designed shoes is effective in preventing relapses in diabetic patients with previous ulceration.

Confidence Intervals↗
PubMed1995

Body sway in diabetic neuropathy.

OBJECTIVE: To evaluate the influence of peripheral neuropathy on body sway assessed by posturography. RESEARCH DESIGN AND METHODS: The age-matched study subjects included 10 insulin-dependent diabetes mellitus (IDDM) patients with peripheral neuropathy (DN), 23 IDDM patients without peripheral neuropathy (D) according to the San Antonio Consensus Conference guidelines, and 21 control subjects (C). All subjects with symptoms and/or clinical signs of postural instability were excluded from the study. RESULTS: The trace surface was significantly larger in the DN than in the C and D groups (P < 0.05), and the trace length was longer in the DN than in the C and D groups (P < 0.01). Mean velocity was faster in the DN than in the other two groups (P < 0.001). A direct relationship was found between the parameters of posturography and some parameters of the nerve conduction velocity. CONCLUSIONS: Diabetic patients with peripheral neuropathy demonstrate a relative deficit in their ability to maintain posture. Posturography allows an early disclosure of the failure of postural control.

Adult↗
PubMed1994

Visual evoked potentials after photostress in insulin-dependent diabetic patients with or without retinopathy.

Visual evoked potentials (VEPs) were assessed under basal conditions and after photostress in normal control subjects, in insulin-dependent diabetic patients with retinopathy (IDDPWR) and in insulin-dependent diabetic patients without retinopathy (IDDP). The VEPs recorded under basal conditions showed a P100 latency significantly higher in IDDP and IDDP-WR eyes than in control eyes and in IDDPWR than in IDDP eyes (P < 0.01). N75-P100 amplitude was significantly lower in IDDP and IDDPWR eyes than in control eyes (P < 0.01). No difference was recorded in the N75-P100 amplitudes between IDDP and IDDPWR eyes. In all eyes, the VEPs recorded after photostress showed an increase in latency and a decrease in amplitude. In both IDDPWR eyes and IDDP eyes VEPs recorded at 20, 40 and 60 s after photostress showed higher mean increments in P100 latency than in C control eyes, and IDDPWR eyes showed higher mean increments in P100 latency than IDDP eyes (IDDP vs control P < 0.01, IDDPWR vs control P < 0.01, IDDPWR vs IDDP P < 0.017). The mean reductions in amplitude observed at 20, 40 and 60 s after photostress in IDDP and IDDPWR eyes were lower than in control eyes (IDDP vs control P = 0.01, IDDPWR vs control P < 0.01, IDDPWR vs IDDP P < 0.01). VEPs were superimposable on the basal VEP (recovery time) at 73.9 s in control eyes, at 88.17 s in IDDP eyes and at 113.3 s in IDDPWR eyes. VEPs after photostress in IDDP patients with normal visual acuity and no fluorangiographic signs of retinopathy may show multiple modifications. This may indicate the presence of an early functional deficiency of the central retinal layers.

Adult↗
PubMed1994

Autonomic neuropathy and transcutaneous oxymetry in diabetic lower extremities.

Transcutaneous oxygen tension is a useful method with which to assess the functional status of skin blood flow. The reduced values observed in diabetic patients have been interpreted as a consequence of peripheral vascular disease. However, diabetic patients show lower transcutaneous oxygen tension values than control subjects with equivalent degrees of peripheral vascular disease, suggesting that additional factors are involved. Since the autonomic nervous system influences peripheral circulation, we studied the relationship between autonomic neuropathy and foot transcutaneous oxymetry in non-insulin-dependent diabetic (NIDDM) patients without peripheral vascular disease. The following age-matched patients were selected and evaluated: control subjects, C, (n = 20), NIDDM patients without autonomic neuropathy, D, (n = 16) and with autonomic neuropathy, DN, (n = 20). All diabetic patients showed lower transcutaneous oxygen tension values than control subjects, while no differences were observed between the diabetic patients with and without autonomic neuropathy. In addition the saturation index that increases in the presence of autonomic neuropathy does not correlate with foot TcPO2. In conclusion autonomic neuropathy does not influence foot TcPO2 and therefore it is unlikely that it contributes to development of foot lesions during induction of foot skin ischaemia.

Autonomic Nervous System↗
PubMed1994

The effects of insulin on plasma mevalonate concentrations in man.

Mevalonate production is a limiting step in cholesterol synthesis. We studied the effects of insulin on plasma mevalonate concentrations during a 3-hour euglycemic hyperinsulinemic clamp study in 10 healthy males starting at 9 h a.m. after 14 h of fasting. Physiological variations in plasma mevalonate were evaluated on a different day from 9 to 12 h a.m. under saline infusion. During the clamp studies, slight but significant decreases were noted for VLDL-triglyceride and VLDL-cholesterol at 120 and 180 min (p < 0.05) and for apolipoprotein B-100 from 60 min on (p < 0.05). Plasma mevalonate decreased significantly by 34 and 41% at 120 and 180 min, respectively (p < 0.001), while the mean percent decrease due to diurnal variations was 12% at 12 h a.m. In conclusion, hyperinsulinemia in the presence of euglycemia acutely decreases the circulating levels of mevalonic acid, the immediate product of HMG CoA reductase in the cholesterol pathway.

Adult↗
PubMed1994

Autonomic neuropathy influences great toe blood pressure.

OBJECTIVE: To assess the influence of autonomic neuropathy on toe blood pressure (TBP), a parameter used currently as an ischemic index. RESEARCH DESIGN AND METHODS: The age-matched study subjects included 20 non-insulin-dependent diabetes mellitus (NIDDM) patients with autonomic neuropathy (DN) and 10 NIDDM patients without autonomic neuropathy (D), assessed by standard cardiovascular tests and galvanic skin response, and 8 control subjects (C). None of the subjects had peripheral vascular disease (PVD) (ankle/brachial index 0.9-1.1. RESULTS: The TBP and toe/brachial index (TBI) were significantly lower in DN than in C and D (P < 0.01). The saturation index (SI), the ratio between foot venous and arterial partial pressure of oxygen (PO2), was significantly higher in DN than in C and D (P < 0.05). An inverse relationship was found between TBI and SI (r = 0.554, P = 0.001). CONCLUSIONS: The autonomic nervous system directly influences peripheral circulation. In diabetic patients without PVD, a failure of sympathetic fibers caused by autonomic neuropathy could lead to a reduction of TBP. Therefore, TBP cannot be used as an ischemic index in diabetic patients.

Analysis of Variance↗