Blunted erythropoietin response to anemia in patients with Type 1 diabetes

BACKGROUND

It is known that patients with renal failure have normochromic normocytic anemia due to impaired endogenous erythropoietin (EPO) synthesis. The aim of this work was to determine whether low serum erythropoietin (s-EPO) levels play a role in the pathogenesis of anemia in patients with Type 1 diabetes without overt nephropathy.

METHODS

We included in the study 13 patients with Type 1 diabetes whose Hb levels were <11 g/dl. Blood cell count, s-EPO, urinary albumin excretion rate (AER), HbA(1c), glomerular filtration rate, serum iron, serum ferritin, the presence of neuropathy, retinopathy and nephropathy were determined.

RESULTS

Ten out of 13 patients with anemia (77%) had a blunted EPO response to anemia. All ten patients with low EPO levels had autonomic neuropathy; five had clinical nephropathy but with serum creatinine<1.6 mg/dl. Three patients were treated with rHuEPO and showed an improvement in their anemia after treatment.

CONCLUSION

The majority of patients with Type 1 diabetes who had anemia also had low EPO levels. The pathogenesis of this phenomenon is probably multifactorial. Autonomic neuropathy appears to play a role, but it is not sufficient, per se, to be the only cause. Dysautonomia might enhance the effect of renal damage.

Efficacy of different Helicobacter pylori eradication regimens in patients affected by insulin-dependent diabetes mellitus

BACKGROUND

Patients with insulin-dependent diabetes mellitus (IDDM) are often affected by chronic infections; antibiotic absorption, however, may be influenced by the disease. H. pylori eradication appears to be reduced in IDDM patients. The aim of the study was to evaluate the efficacy of the most common H. pylori eradication regimens in a population of IDDM-infected patients.

METHODS

One hundred and seventy-two IDDM patients were evaluated. H. pylori infection was assessed through the 13C-urea breath test. Infected patients were randomly assigned to three different standard 7-day eradication regimens: 1) amoxicillin, clarithromycin, pantoprazole; 2) tinidazole, clarithromycin, ranitidine bismuth citrate; or 3) tinidazole, clarithromycin, pantoprazole. Patients in whom eradication was not successful in the first cycle were subsequently submitted to a 7-day therapy with tinidazole, tetracycline, bismuth, and pantoprazole.

RESULTS

Thirty-seven per cent of IDDM patients were infected. None of the triple therapies used provided an eradication higher than 62%. Conversely, the quadruple regimen was successful in 88% of the patients. Ten per cent of the subjects undergoing the triple therapies showed minor side effects, without significant differences among groups, whereas side effects occurred in 25% of the patients treated with the quadruple therapy (P < 0.05).

CONCLUSIONS

IDDM patients show a low H. pylori eradication rate with a standard triple therapy regardless of the regimen utilized, the dosage and/or the duration of the therapy used appearing not to be sufficient to eradicate the infection efficiently. The use of a quadruple regimen leads to the cure of a large percentage of the infected patients in whom the eradication was unsuccessful in the first therapy, although it is accompanied by a greater incidence of minor side effects.

Purine metabolites and malondialdehyde in platelets of diabetic patients

The concentration of some of the purine nucleotides and their metabolites together with that of malondialdehyde (MDA) have been measured in resting and stimulated platelets of type 1 and type 2 diabetic patients. While control platelets show a net decrease of guanosine triphosphate (GTP) (3.1 vs. 2.3 nmol per 10(9) platelets) and guanosine diphosphate (GDP) (3.0 vs. 2.0 nmol per 10(9) platelets) and a significant increase of adenosine (0.04 vs. 0.55 nmol per 10(9) platelets) with platelet stimulation, platelets of type 1 and type 2 diabetic patients have a lesser change of these metabolites (GTP, 2.6 vs. 2.4; GDP, 2.3 vs. 2.4; adenosine, 0.04 vs. 0.30 (P < 0.05 vs. control) nmol per 10(9) platelets in type 1 diabetics; GTP, 2.4 vs. 2.7; GDP, 2.4 vs. 2.1; adenosine, 0.08 vs. 0.32 (P < 0.05 vs. control) nmol per 10(9) platelets in type 2 diabetics). These results indicate that the change (stimulated minus resting) of GTP, GDP and adenosine in diabetic platelets is significantly different from that of controls (P < 0.001). Moreover, the amount of MDA produced during platelet activation seems to be lower than controls only in type 2 diabetes (1.81 vs. 2.86 nmol per 10(9) platelets, P < 0.05). These results seem to indicate that a difference in the pattern of platelet nucleotides could be an important feature even in well-controlled diabetes, while MDA is probably modified only in association with the late vascular complications of diabetes.

Insulin-dependent diabetes mellitus affects eradication rate of Helicobacter pylori infection

BACKGROUND

Patients with insulin-dependent diabetes mellitus (IDDM) are often affected by chronic infections; however, antibiotic absorption may be influenced by the disease. Helicobacter pylori, the most common gastric infection worldwide, is the main acquired factor in the pathogenesis of gastritis and peptic ulcer. The aim of the study was to compare the H. pylori eradication rate obtained with a standard 7-day antibiotic regimen in a group of IDDM H. pylori infected patients and in a control group of infected dyspeptic patients.

METHODS

Thirty-one patients (18 male, 13 female, 39+/-12 years) affected by IDDM and H. pylori infection, and 50 dyspeptic infected patients (23 male, 17 female, 37+/-10 years) were evaluated. H. pylori infection was assessed through 13C-urea breath test. A triple therapy with amoxycillin (1 g b.i.d.), clarithromycin (250 mg t.i.d.) and pantoprazole (40 mg b.i.d.) was given to both groups at the time of diagnosis for 7 days. Cure was defined as the absence of H. pylori infection, assessed by 13C-urea breath test, 6 weeks after completing anti-microbial therapy. Effects of H. pylori eradication on gastrointestinal symptoms (pyrosis, epigastric pain, belching, bloating, halitosis and nausea) were also evaluated.

RESULTS

All enrolled patients completed the study. When compared to dyspeptic patients, the eradication rate was significantly lower in IDDM patients: 92% (46/50) versus 65% (20/31), respectively (P < 0.002). IDDM patients infected by H. pylori showed a different prevalence of some of the gastrointestinal symptoms assessed when compared to the infected dyspeptic patients; in particular, pyrosis, epigastric pain and belching were significantly more prevalent in the infected dyspeptic group. After H. pylori eradication, both groups showed a significant reduction of the intensity of all the gastrointestinal symptoms evaluated, except for nausea.

CONCLUSIONS

IDDM patients showed a significantly lower H. pylori eradication rate when compared to that observed in dyspeptic subjects. The dosage and/or the duration of a standard eradication regimen does not appear to be sufficient to eradicate the infection in IDDM patients. The impairment of the gastrointestinal mucosa microvasculature with a reduction of antibiotic absorption, or the frequent use of antibiotics for other infections with development of resistant strains, may be the mechanisms underlying the observation.

The use of dynamic posturography to detect neurosensorial disorder in IDDM without clinical neuropathy

The main aim was to evaluate the relative importance of sensory interactions for postural stability in 45 patients with insulin-dependent diabetes mellitus (IDDM) with and without peripheral neuropathy. All subjects had normal electronystagmography. Dynamic posturography provides functional, selective testing of three sensory modalities in maintenance of balance, i.e., vestibular, visual, and somatosensory. The Sensory Organization Test (SOT) includes six test conditions during which the subject tries to maintain an upright stance with as little sway as possible. The subject stands on a movable platform facing a square visual surrounding, which can be rotated independently. The test is performed first with the eyes open, then with the eyes closed. The second component of posturography testing consists of the Motor Control Test (MCT) concerning motor responses routinely used in balance maintenance. Compared to control subjects, IDDM patients with peripheral neuropathy but not patients without neuropathy showed lower scores for test conditions SOT 1 (analysis of variance, ANOVA F = 8.3; Scheffe test: p = 0.0007), SOT 2 (F = 6.6; p = 0.004), SOT 3 (F = 3.4; p = 0.04), and SOT 6 (F = 3.4; p = 0.04). The muscle response latencies in MCT were prolonged for small forward perturbations (F = 4.6; p = 0.02) in neuropathic patients (148.3+/-14.2 ms) with respect to control subjects, but not in non-neuropathic patients with respect to control subjects (135.2+/-13.3 ms). Sural (r = 0.2; p = 0.002) and peroneal (r = 0.12; p = 0.02) nerve conduction velocities showed significant correlations with muscle response latencies of MCT for small forward perturbations. Our results suggest a subclinical dysequilibrium in IDDM patients with peripheral neuropathy. The results of dynamic posturography may reflect the impairment of the somatosensory system, rather than a specific lesion of vestibular and/or visual modalities.

Early renal involvement in diabetes mellitus: comparison of renal Doppler US and radioisotope evaluation of glomerular hyperfiltration

PURPOSE

To evaluate the usefulness of Doppler ultrasonography (US) in the diagnosis of hyperfiltration in patients with insulin-dependent diabetes mellitus (IDDM).

MATERIALS AND METHODS

Eighty-one consecutive patients with IDDM were studied. All patients were normotensive and had normal creatinine and blood urea nitrogen levels. The glomerular filtration rate (GFR) was evaluated by means of plasma clearance of chromium-51 ethylenediaminetetraacetic acid, urinary albumin excretion, US evaluation of renal volume, and Doppler evaluation of resistance index (RI) in the renal interlobar arteries. The patients were divided according to GFR into the following groups: those with hyperfiltering kidneys (group 1, n = 40) and those with normofiltering kidneys (group 2, n = 41).

RESULTS

The median renal volume was 351 mL (95% CI = 337 mL, 379 mL) in group 1 and 318 mL (95% CI = 300 mL, 335 mL) in group 2 (P = .005). The number of patients with microalbuminuria was significantly lower in group 1 than in group 2 (P = .02). The median RI was significantly lower in group 1 (0.55; 95% CI = 0.53, 0.57) than in group 2 (0.57; 95% CI = 0.56, 0.59) (P = .04). An RI of less than 0.5, a renal volume greater than 410 mL/m2, and the absence of microalbuminuria were independent predictors of hyperfiltration. An RI of less than 0.5 and a renal volume greater than 410 mL/m2 showed high specificity (98% and 95%, respectively) and poor sensitivity (25% and 23%, respectively) in the diagnosis of hyperfiltration in IDDM patients.

CONCLUSION

Both RI and renal volume showed correlation with GFR, but neither parameter is sufficiently sensitive in screening for hyperfiltration in IDDM patients.

Hyperfiltration in patients with type I diabetes mellitus: a prevalence study

AIM

An increase in glomerular filtration rate (GFR) and renal plasma flow (EFPR) may be considered as prognostic factors for the progression of diabetic nephropathy; however the real predicting value of hyperfiltration in the development of incipient and overt nephropathy is as yet unknown. We have examined the prevalence of hyperfiltration in a population of normotensive adult IDDM patients and the possible effect of long-term metabolic control on glomerular hemodynamics.

MATERIALS AND METHODS

We measured GFR and ERPF values in 177 normotensive, normoalbuminuric insulin-dependent diabetic patients and in 30 healthy subjects by single bolus intravenous injection of 1 miroCu/kg [51Cr]-EDTA and 0.2 microCu/kg [125I]-Hippuran intravenously. We have correlated the GFR values with parameters of metabolic control over the last 3 years and with age, sex, and duration of diabetes.

RESULTS

Patients with a GFR greater than the 95 degrees percentile value of controls (135 ml/min/1,73 m2) were defined as hyperfiltering. They represented the 55.9% (99/177) of our population. We found a strong correlation between GFR and ERPF (p <0.001), and between GFR and average HbA1c levels (p = 0.016) in multiple regression analysis, with age, sex, ERPF, and average HbA1c levels entered as variables (r2 = 0.45). There appeared to be no correlation with the duration of the disease.

CONCLUSIONS

Long-term hyperglycemia provides a significant contribution in GFR and a poor metabolic control is predictive of overt nephropathy. In this study hyperfiltration does not appear to be the major factor of diabetic nephropathy. A follow-up of these patients is necessary to clarify the role of hyperfiltration in the development of overt nephropathy in diabetes.

From synthetic coiled coils to functional proteins: automated design of a receptor for the calmodulin-binding domain of calcineurin

A series of synthetic receptors capable of binding to the calmodulin-binding domain of calcineurin (CN393-414) was designed, synthesized and characterized. The design was accomplished by docking CN393-414 against a two-helix receptor, using an idealized three-stranded coiled coil as a starting geometry. The sequence of the receptor was chosen using a side-chain re-packing program, which employed a genetic algorithm to select potential binders from a total of 7.5x10(6) possible sequences. A total of 25 receptors were prepared, representing 13 sequences predicted by the algorithm as well as 12 related sequences that were not predicted. The receptors were characterized by CD spectroscopy, analytical ultracentrifugation, and binding assays. The receptors predicted by the algorithm bound CN393-414 with apparent dissociation constants ranging from 0.2 microM to >50 microM. Many of the receptors that were not predicted by the algorithm also bound to CN393-414. Methods to circumvent this problem and to improve the automated design of functional proteins are discussed.

Distortion-product otoacoustic emissions and selective sensorineural loss in IDDM

OBJECTIVE

To provide information about possible subclinical damage of the cochlear outer hair cells (OHCs) by means of transiently evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) in subjects with IDDM.

RESEARCH DESIGN AND METHODS

TEOAEs and DPOAEs were recorded in 47 IDDM patients with normal hearing and in age- and sex-matched nondiabetic subjects. Peripheral neuropathy was diagnosed by nerve conduction velocity (NCV) at the peroneal and surral nerves.

RESULTS

A subclinical peripheral neuropathy was found in 15 diabetic patients. Mean TEOAE amplitude was found to be significantly reduced in diabetic patients with a reduced NCV (7.6 +/- 3.2 dB; Scheffé's test: P = 0.03), but not in those without neuropathy (9.5 +/- 4.3 dB), with respect to control subjects (11 +/- 3.1 dB). Neuropathic patients also showed mean reduced DPOAE amplitude values in the region of middle and high frequencies from 1,306 to 5,200 Hz (P < 0.05), whereas no difference was found at the lowest-frequency amplitudes. A frequency-selective reduction of DPOAEs was also found in non-neuropathic patients (P < 0.05) in the region of higher frequencies at 3,284, 4,126, and 5,200 Hz compared with control subjects. No correlations were found among duration of diabetes, HbA1c values, TEOAEs and DPOAEs.

CONCLUSIONS

Our results suggest that IDDM patients show an early abnormality of the micromechanical properties of the OHCs. In IDDM patients without a subclinical peripheral neuropathy, damage is limited to the higher frequencies and can be detected only by DPOAEs, whereas in IDDM patients with neuropathy, damage also involves the middle range of frequencies and can be detected by TEOAEs and DPOAEs. Therefore, DPOAEs seem to be able to detect the earliest cochlear selective-frequency dysfunction in IDDM patients without peripheral neuropathy. DPOAEs appear to be of greater clinical interest than TEOAEs; the former seem to be frequency specific and can be recorded at any chosen frequency, including high frequencies.

Helicobacter pylori infection in patients affected by insulin-dependent diabetes mellitus

BACKGROUND/AIM

Insulin-dependent diabetes mellitus (IDDM) is the result of an autoimmune destruction of pancreatic Langerhans beta cells. Helicobacter pylori infection, the most common cause of gastritis and peptic ulcer, has been associated with some autoimmune diseases. The aim of this study was to evaluate the prevalence of H. pylori infection and gastrointestinal (GI) symptoms in patients with IDDM.

METHODS

116 patients (50 males and 66 females, mean age: 35 +/- 11 years) affected by IDDM were evaluated; 50 healthy subjects matched for age and sex were utilized as a control group. H. pylori infection was determined by a [13C]urea breath test. IDDM duration, daily dosage of insulin and prevalence of GI symptoms (bloating, pyrosis, epigastric pain, belching, halitosis, nausea) were assessed.

RESULTS

The prevalence of H. pylori infection was similar in IDDM patients and in controls (37 vs 34%, respectively). In both groups, the mean age was higher in infected subjects. The mean IDDM duration was significantly greater in infected patients (19 +/- 12 vs 13 +/- 10 years, P < 0.006). Prevalence of infection was directly related to the duration of IDDM (<1 year, 23%; 1-3 years, 32%; >3 years, 40%). The daily dosage of insulin did not differ between infected and non-infected subjects. H. pylori contaminated patients showed a significantly higher prevalence of bloating, pyrosis and epigastric pain when compared with non-infected subjects; conversely, prevalence of belching, halitosis and nausea did not differ between groups.

CONCLUSION

The prevalence of H. pylori infection is high in patients affected by IDDM; however, it does not differ from the infection rate observed in a control group. The rate of infection increases with IDDM duration. Bloating, pyrosis and epigastric pain appear to define infection status better.

Defective plasma antioxidant defenses and enhanced susceptibility to lipid peroxidation in uncomplicated IDDM

Oxidative stress is postulated to be increased in patients with IDDM. Accumulating evidence suggests that oxidative cell injury caused by free radicals contributes to the development of IDDM complications. On the other side, a decreased efficiency of antioxidant defenses (both enzymatic and nonenzymatic) seems to correlate with the severity of pathological tissue changes in IDDM. Thus, we determined plasma antioxidant defenses, measuring the total radical-trapping antioxidant capacity (TRAP) and the two markers of oxidative stress, lipid hydroperoxides (ROOHs) and conjugated dienes, in 72 patients with well-controlled IDDM and without evident complications, compared with 45 nondiabetic subjects. Compared with control subjects, IDDM patients showed significantly reduced plasma TRAP (669 +/- 131 vs. 955 +/- 104 micromol/l, P < 0.001) and significantly increased levels of ROOHs (7.13 +/- 2.11 vs. 2.10 +/- 0.71 micromol/l, P < 0.001) and conjugated dienes (0.0368 +/- 0.0027 vs. 0.0328 +/- 0.0023 arbitrary units [AU], P < 0.01), especially in the trans-trans conformation (0.0340 +/- 0.0028 vs. 0.0259 +/- 0.0022 AU, P < 0.001), with a concurrent reduction of conjugated dienes in the cis-trans conformation (0.0028 +/- 0.0011 vs. 0.0069 +/- 0.0012 AU, P < 0.001). The oxidative parameters studied did not appear to be correlated with metabolic control (HbA1c levels) and lipid profile (cholesterol or triglyceride levels). The reduced TRAP and the increased ROOH and conjugated diene plasma levels, together with the decreased ratio of cis-trans/trans-trans conjugated dienes, which reflects an altered redox status of plasma, indicate that in IDDM patients, oxidative stress is enhanced and antioxidant defenses are defective, regardless of diabetes duration, metabolic control, or presence of complications.

Charcot's foot

Diabetic osteoarthropathy is a chronic progressive arthropathy involving the bones and joints being constantly associated to somatic and autonomic peripheral neuropathy. The pathogenesis is related to sensory and motor neuropathy with morphologic foot alterations, relaxation and abnormal position on walking till complete collapse of the foot shown by the depressed longitudinal medial arch. Bone reabsorption due to osteoclasis and increased blood flow until osteomalacia appears, is characteristic of this arthropathy. The clinical features vary according to the location and severity of articular impairment and the stage of identification. The metatarsophalangeal or tarsometatarsal joint may be involved. The typical manifestation of Charcot's foot is plantar ulcer of variable location according to the weight-bearing area. Treatment tends to reduce the abnormal stress predisposing to ulceration with tailored footwear and orthoses.

Perioperative treatment of the diabetic patient

The diabetic patient is frequently undergoing surgery for the underlying disease and its complications. Before referring the patient to surgery the diabetologist should carefully evaluate the presence of complications, cardiovascular, renal and neurologic disorders in particular. Generally no problems are posed by patients with NIDDM undergoing elective surgery. For more demanding patients and for those with IDDM the most effective and ready treatment is the continuous intravenous infusion of glucose, insulin and potassium. With this regimen, it is possible to perform major surgery in diabetics with a lower risk.

The foot clinic. Multidisciplinary management of the patient with diabetic foot

Treatment of a complex disease as the diabetic foot requires a multidisciplinary management with the close collaboration of a team for care. The most important members of the team are the diabetologist as coordinator, the vascular surgeon, the orthopedist, the radiologist, the orthopedic technician, the podiatrist and the nurse specialist. The care based on this arrangement should be carried out in dedicated rooms and times to exploit at best the organizational potential in the patient's interest, implemented in the foot clinic.

Lower limb ischemia

Diabetes mellitus is the major cause of nontraumatic amputations in the industrialized countries. In 1980 the scientific societies of diabetology and the patients' associations subscribed at St. Vincent a declaration together with the WHO, where a 50% decrease in amputations was among the primary objectives of clinical diabetology. The main cause of amputations is foot ischemia related to obliterating peripheral arterial disease, more diffuse and severe in diabetics, typically affecting the infrapopliteal vessels. Clinical patterns of foot ischemia include superficial necrotic areas and gangrene involving the entire foot with necrosis of all anatomic planes. Infection is a common complication with a negative impact on prognosis. Definitive treatment of ischemia is achieved with revascularization which at present due to the advances in diagnostic procedures can be performed in diabetics with the same effectiveness observed in non diabetics.

A multicenter study on the prevalence of diabetic neuropathy in Italy. Italian Diabetic Neuropathy Committee

OBJECTIVE

The prevalence of neuropathy, a common complication of diabetes, was determined in diabetic patients recruited from 109 outpatient diabetes clinics in Italy.

RESEARCH DESIGN AND METHODS

Neuropathy was diagnosed using the Diabetic Neuropathy Index (DNI), a standardized examination developed for use in the outpatient setting. A total of 8,757 diabetic patients were studied, 51.2% men and 48.8% women, with average and median ages of 56 and 58 years, respectively.

RESULTS

Of the 8,757 patients, 32.3% had neuropathy, defined as a positive score of > 2 points on the DNI. A total of 2,033 (49.6% men and 50.4% women) were administered the Diabetic Neuropathy Score (DNS), the second component of the screening program, by a neurologist. This component consists of a quantitative neurological examination and nerve conduction studies that together provide a summated score. A total of 335 patients (16.5%) were not neuropathic, and 395 (19.4%) had borderline, 453 (22.3%) mild, 592 (29.1%) moderate, and 258 (12.7%) severe neuropathy. The concordance between a positive score on the DNI and a DNS indicating neuropathy was 83.5%. The severity of neuropathy increased with both age and disease duration. Of patients with neuropathy, 64.1% had an average age between 58 and 59 years with a disease duration between 12.4 +/- 8.4 years (mild neuropathy) and 15.6 +/- 9.7 years (severe neuropathy).

CONCLUSIONS

Neuropathy is a common complication of diabetes and, in this study, was present in 32.3% of all patients. An increased awareness of the high prevalence of neuropathy can lead to early therapeutic intervention and possible prevention of later neuropathic complications, such as infection and foot ulcers.

Cochlear dysfunction in IDDM patients with subclinical peripheral neuropathy

OBJECTIVE

To investigate the function of the auditory pathway from the cochlea to the auditory cortex in subjects with IDDM.

RESEARCH DESIGN AND METHODS

Brain stem, middle-, and long-latency auditory-evoked responses and evoked otoacoustic emissions were measured in 48 normally hearing IDDM patients and in age- and sex-matched nondiabetic subjects. Peripheral neuropathy was diagnosed by nerve conduction velocity (NCV) at the peroneal and sural nerves. Auditory brain stem responses (ABRs) reflect auditory pathway function within the brain stem; middle-latency responses (MLRs) and long-latency responses (LLRs) originate from the auditory cortex; and evoked otoacoustic emissions (EOAEs) give objective information about preneural, mechanical elements of the cochlear function.

RESULTS

A subclinical peripheral neuropathy was found in 12 diabetic patients. We found higher latencies of waves I (t = 4.4, P < 0.0001), III (t = 3.7, P = 0.0004), and V (t = 2.7, P = 0.008) of ABRs in diabetic patients (I: 1.7 +/- 0.13 ms; III: 3.9 +/- 0.17 ms; V: 5.7 +/- 0.24 ms), compared with those of the control group (I: 1.6 +/- 0.13 ms; III: 3.7 +/- 0.18 ms; V: 5.6 +/- 0.17 ms). However, neither central transmission time (i.e., the wave interpeak I-V) nor MLRs and LLRs were found to be significantly different in diabetic and control subjects. Mean EOAE amplitude was found to be significantly reduced (F = 4.2, P = 0.02) in diabetic patients with a reduced NCV (7.6 +/- 3.9 dB; Scheffé test: P = 0.03), but not in those without neuropathy (9.1 +/- 4.2 dB), compared with the control group (10.8 +/- 3.1 dB). No correlations were found between duration of diabetes and EOAEs or between sural NCV and peroneal NCV and metabolic control. EOAEs were not correlated with peroneal and sural NCVs.

CONCLUSIONS

Our results indicate that the early preneural dysfunction of cochlear receptors causes a prolonged activation of the peripheral portion of the auditory pathway, while signal conduction along the central auditory pathway was shown to be normal in diabetes.

Postural variations of pulmonary diffusing capacity in insulin-dependent diabetes mellitus

STUDY OBJECTIVE

To assess whether posture-related changes of diffusing capacity could be considered as an early sensitive marker of pulmonary abnormalities in patients with insulin-dependent diabetes mellitus (IDDM) and whether the postural variations of pulmonary capillary blood volume (Vc) could reflect the lung capillary damage that characterizes the diabetic microangiopathy.

DESIGN

Carbon monoxide diffusing capacity (DCO) was measured by the single-breath method. Four DCO measurements, two in sitting and two in supine position, were performed in each subject using gas mixtures containing different oxygen concentrations. Membrane and capillary volume components of the diffusion capacity were calculated and both were expressed as absolute value and corrected by alveolar volume (VA).

PATIENTS

Twenty IDDM patients and 20 normal subjects matched for age and sex were studied.

MEASUREMENTS AND RESULTS

The IDDM patients showed normal pulmonary volumes and flows. No significant differences between the two groups were found for DCO, coefficient of diffusion, Vc, and pulmonary capillary blood volume corrected by alveolar volume in sitting position. All these indexes significantly increased in normal subjects but not in diabetics, by changing the posture of the subject from sitting to supine position. In a multivariate analysis, the presence of diabetes mellitus and the age of the subjects were the only significant predictors of Vc postural changes.

CONCLUSIONS

This postural test, adjusted for age, could be included in a screening diagnostic procedure for an early assessment of pulmonary abnormalities in diabetic patients. The lack of Vc postural increase in diabetics could reflect the presence of a microangiopathy involving the pulmonary small vessels.

NA+/K+ ATPase impairment and experimental glycation: the role of glucose autoxidation

Non enzymatic glycation could be involved in the early impairment of Na+/K+ ATPase that occurs in sciatic nerve of diabetic rats. In fact, decrease of Na+/K+ ATPase activity is one of the first alterations showed in experimental diabetic neuropathy. In this respect, it is known that in the presence of transition metals under physiological conditions, glucose can autoxidize yielding hydrogen peroxide (H2O2) and free radical intermediates, which, in turn, inhibit the cation pump. Our experiments were designed to determine if glucose autoxidation has any relevance in the early steps of Na+/K+ ATPase experimental glycation. Compared experiments with and without the sodium borohydride (NaBH4) reduction step demonstrated that incubation of brain Na+/K+ ATPase with glucose 6-phosphate (G 6-P) and trace metals induced a significant decrease in enzyme activity dramatically enhanced by addition of copper (Cu2+). A concomitant production of H2O2 was noticed. The presence of diethylenetriaminepentaacetic acid (DTPA), a strong metal chelator, completely prevented Na+/K+ ATPase impairment and hydrogen-peroxide formation. No gross structural and conformational alterations of the enzyme can be demonstrated by intrinsic and extrinsic fluorescence measurements. Our results suggest that during the exposure of brain NA+/K+ ATPase to glucose 6-phosphate in vitro (experimental glycation), the decrease in activity can be correlated, at lease in the early phases, to metal-catalyzed production of oxidative species, such as H2O2, through the glucose autoxidation process, and not to glucose attachment to the enzyme. Since plasma hydroperoxides and copper appear to be elevated in diabetic patients with complications, our data suggest a critical role for oxidative reactions in the pathophysiology of the chronic complications of diabetes like neuropathy.

Prevalence of coeliac disease in type I diabetes: a multicentre study

The aim of this study was to point out the prevalence ratio and the clinical presentation of coeliac disease (CD) in a large group of insulin-dependent diabetes mellitus (IDDM) patients.

PATIENTS AND METHODS

1114 patients affected by IDDM were screened for CD using antigliadin and antiendomysium antibodies. Patients who were positive for at least one test underwent an endoscopic biopsy of the descending duodenum in order to verify the presence of villous atrophy. Subjects with CD started a gluten-free diet and underwent a clinical follow up.

RESULTS

Villous atrophy was found in 63 patients (5.6%). Among the Italian population, the rate was 7%. Twenty-four percent of coeliac patients presented with diarrhoea, while 22% were completely symptom-free. A significant correlation was found between the presence of villous atrophy and the duration and onset of diabetes.

CONCLUSIONS

The prevalence of CD in IDDM is higher than previously reported, although the ratio range in different centres from 1.7 to 10%, probably due to both environmental and genetic factors. Twenty-two percent of coeliac patients were completely symptom-free. The prevalence seems to be significantly related to the duration and onset of IDDM.

Lactate dehydrogenase activity of platelets in diabetes mellitus

Lactate dehydrogenase (L-lactate : NAD+ oxidoreductase, EC 1.1.1.27) activity has been measured on the subpopulations of platelets obtained from blood of diabetic patients. Small, but not large platelets show a lactate dehydrogenase activity higher than that of controls. Moreover, a positive statistically significant correlation was found between the activity of small platelets and the percent of glycated haemoglobin, while no correlation was obtained in the case of large platelets. Since we previously demonstrated that lactate dehydrogenase activity of small platelets is exceedingly high in some clinical and experimental conditions, our results not only confirm the involvement of platelets in diabetes but provide more evidence in support of our previous hypothesis of a relationship between lactate dehydrogenase and in-vivo platelet activation.

Daily energy metabolism in patients with type 1 diabetes mellitus

OBJECTIVE

We evaluated the daily energy balance and main substrate utilization in Type 1 insulin dependent diabetic patients and healthy volunteers.

METHODS

Ten patients with Type 1 diabetes mellitus and eight healthy volunteers were studied. Diabetic patients were well controlled under intensive insulin treatment (0.6 UI/kg body weight, HbA1c = 5.5 +/- 0.7%). During the 30 hours each subject spent in the respiration chamber VO2, VCO2, respiratory quotient, daily energy intake, 24-hour, day-time, night-time and basal energy expenditure as well as energy expenditure during exercise (at 40% maximal exercise capacity), main substrate oxidation (carbohydrates, lipids and proteins) and overall diet-induced thermogenesis, were measured. The results were corrected for 24-hour urinary nitrogen loss.

RESULTS

Diet-induced thermogenesis, expressed as percent of energy intake, was found to be significantly lower in diabetic patients than in control subjects (6.69 +/- 1.29% vs 11.8 +/- 4.71% of energy intake, p < 0.05). A negative correlation was found between diet-induced thermogenesis and daily average glycemia for diabetic patients (r = -0.65, p < 0.01). Energy expenditure during exercise, calculated in terms of net work efficiency, was not different between the two groups.

CONCLUSIONS

In conclusion, since diet-induced thermogenesis is highly correlated with the theoretical cost of glucose storage and since no difference was found in carbohydrate oxidation, glucose storage in diabetic patients is probably reduced when hyperglycemia occurs. Diabetic patients in good metabolic control are able to perform mild exercise with a work efficiency very similar to that of control subjects.