Diabetic neuropathy

Macrophage infiltration and death in the nerve during the early phases of experimental diabetic neuropathy: a process concomitant with endoneurial induction of IL-1beta and p75NTR

This study describes the infiltration and death of monocyte/macrophages and concomitant endoneurial expression of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) and neurotrophin receptor p75 (p75NTR) in the sciatic nerve at the early phases of experimental diabetic neuropathy induced in Lewis rats by streptozotocin (STZ) intraperitoneal injection. Immunocytochemistry and single nerve fiber immunostaining showed the presence of macrophages in diabetic nerves by weeks 2 and 3 after STZ administration, and the 15% of these cells were TUNEL positive. IL-1beta was evident in scattered macrophages, and along few isolated nerve fibers until week 5, when it became undetectable, in concomitance with complete endoneurial clearance of macrophages. p75NTR showed an up-regulation in the sciatic nerve of diabetic rats that began by week 3 after STZ administration, reached its peak by week 5, and returned then to a barely detectable level by week 6. These findings seem to indicate that macrophages and IL-1beta may be involved in the pathogenesis of diabetic neuropathy, participating not only to nerve damage but also to the promotion of an attempt of regeneration via p75NTR induction.

Somatosensory loss increases vestibulospinal sensitivity

To determine whether subjects with somatosensory loss show a compensatory increase in sensitivity to vestibular stimulation, we compared the amplitude of postural lean in response to four different intensities of bipolar galvanic stimulation in subjects with diabetic peripheral neuropathy (PNP) and age-matched control subjects. To determine whether healthy and neuropathic subjects show similar increases in sensitivity to galvanic vestibular stimulation when standing on unstable surfaces, both groups were exposed to galvanic stimulation while standing on a compliant foam surface. In these experiments, a 3-s pulse of galvanic current was administered to subjects standing with eyes closed and their heads turned toward one shoulder (anodal current on the forward mastoid). Anterior body tilt, as measured by center of foot pressure (CoP), increased proportionately with increasing galvanic vestibular stimulation intensity for all subjects. Subjects with peripheral neuropathy showed larger forward CoP displacement in response to galvanic stimulation than control subjects. The largest differences between neuropathy and control subjects were at the highest galvanic intensities, indicating an increased sensitivity to vestibular stimulation. Neuropathy subjects showed a larger increase in sensitivity to vestibular stimulation when standing on compliant foam than control subjects. The effect of galvanic stimulation was larger on the movement of the trunk segment in space than on the body's center of mass (CoM) angle, suggesting that the vestibular system acts to control trunk orientation rather than to control whole body posture. This study provides evidence for an increase in the sensitivity of the postural control system to vestibular stimulation when somatosensory information from the surface is disrupted either by peripheral neuropathy or by standing on an unstable surface. Simulations from a simple model of postural orientation incorporating feedback from the vestibular and somatosensory systems suggest that the increase in body lean in response to galvanic current in subjects with neuropathy could be reproduced only if central vestibular gain was increased when peripheral somatosensory gain was decreased. The larger effects of galvanic vestibular stimulation on the trunk than on the body's CoM suggest that the vestibular system may act to control postural orientation via control of the trunk in space.

Hyper-responsivity in a subset of C-fiber nociceptors in a model of painful diabetic neuropathy in the rat

While clinical characteristics of diabetic painful neuropathy are well described, the underlying electrophysiological basis of the exaggerated painful response to stimuli, as well as the presence of spontaneous pain, are poorly understood. In order to elucidate peripheral contributions to painful diabetic neuropathy, we quantitatively evaluated the function of C-fibers in a rat model of painful diabetic neuropathy, diabetes induced by the pancreatic beta-cell toxin streptozotocin. While there was no significant effect of diabetes on conduction velocity, mechanical threshold or spontaneous activity, the number of action potentials in response to sustained threshold and suprathreshold mechanical stimuli was significantly increased in the diabetic rats. Moreover, there was a clustering of responses of C-fibers in diabetic rats; while two-thirds of C-fibers fired at the same mean frequency as C-fibers in control rats, one-third of C-fibers in diabetic rats were markedly hyper-responsive, demonstrating a threefold increase in firing frequency. The high-firing-frequency C-fibers in rats with diabetes also had faster conduction velocity than the low-firing-frequency C-fibers in rats with diabetes or in C-fibers in control rats. The hyper-responsiveness was characterized by a selective increase of the shortest interspike intervals (<100ms) in the burst component (first 10s) of the response to a sustained suprathreshold stimulus; in the plateau phase (last 50s) of the response to a 60-s suprathreshold stimulus, we found a selective increase of interspike intervals between 100 and 300ms in hyper-responsive C-fibers in rats with diabetes. The hyper-responsiveness did not correlate with mechanical threshold, presence of spontaneous activity or location of the fiber's receptive field. In summary, in an established model of painful diabetic neuropathy in the rat, a subset of C-fibers demonstrated a marked hyper-responsiveness to mechanical stimuli. The subset was also found to have a greater mean conduction velocity than the fibers not demonstrating this hyper-responsivity. The present findings suggest that study of individual neurons in vitro may allow elucidation of the ionic basis of enhanced nociception in diabetic neuropathy.

Cervicobrachial involvement in diabetic radiculoplexopathy

Diabetic radiculoplexopathy is commonly viewed as a condition affecting the lower extremities. However, other regions may also be affected and the presence of upper extremity involvement has rarely been emphasized. Our goal was to illustrate the clinical features of arm involvement in this condition. Of 60 patients with diabetic lumbosacral radiculoplexopathy, we identified 9 who also had upper extremity involvement. The study included 8 men and 1 woman, ranging in age from 36 to 71 years. Upper limb involvement developed simultaneously with the onset of lower limb disorder in 1 patient, preceded it by 2 months in another patient, and occurred between 3 weeks and 15 months later in the remaining 7. In 5 cases, arm involvement developed after symptoms in the legs began to improve. The upper extremity weakness affected the hands and forearms most severely. It was unilateral in 5 patients and bilateral but asymmetric in 4. Pain was often present, but it was not a prominent feature. In most patients, neurologic deficits in the arms improved spontaneously after 2-9 months. We conclude that diabetic radiculoplexopathy may involve the cervical region before, after, or simultaneously with the lumbosacral syndrome. The upper limb process is similar to that in the legs, with subacutely progressive weakness and pain followed by spontaneous recovery.

Autonomic nervous function assessment using thermal reactivity of microcirculation

There are only a few reliable objective methods of diagnosing peripheral neuronal damage suitable for routine use; the most important is based on measurement of nerve conduction velocity, which only shows changes when severe disturbances are already present. However, it is precisely at this stage that the possibilities of therapy are no longer satisfactory. As small fibres are affected earlier in the course of most forms of PNP than the large ones, assessment of afferent as well as efferent C-fibre function gains importance in the management of this widespread disease. In assessment of autonomic dysfunction, variability of the heartbeat with deep breathing or the Valsalva manoeuvre is a good and generally accepted test, although not strongly associated with other PNP test abnormalities. However, axonal degeneration starts in the most distal parts of the axon due to impaired axonal transport. Therefore, the longest C-fibres, i.e. in the lower extremities, are affected first, and incipient changes are most prominent there. For this reason HLDF, a reflex response of the skin blood flow stimulated by heat, has advantages in assessment of early C-fibre dysfunction. Considering the fact that the afferent and efferent sympathetic C-fibres are involved in regulation of microcirculation, the skin blood flow regulation is investigated by means of laser Doppler flowmetry. The microcirculation is stimulated by heat and the reaction of microcirculation is assessed as a value for the function of afferent and efferent (sympathetic) C-fibres. The results of this method are in close correlation with electrophysiologic tests, which is not achieved with sudomotor function.

Neurological changes induced by stress in streptozotocin diabetic rats

Previous studies from our laboratory demonstrated that chronic stress produces molecular, morphological, and ultrastructural changes in the rat hippocampus that are accompanied by cognitive deficits. Glucocorticoid impairment of glucose utilization is proposed as a causative factor involved in stress-induced changes. Current studies have examined the neurological changes induced by stress in rats with a preexisting strain upon their homeostatic load--namely, in streptozotocin (stz)-diabetic rats. Administration of stz (70 mg/kg, i.v.) produced diabetic symptoms such as weight loss, polyuria, polydipsia, hyperglycemia, and neuroendocrine dysfunction. Morphological analysis of hippocampal neurons revealed that diabetes alone produced dendritic atrophy of CA3 pyramidal neurons, an effect potentiated by 7 days of restraint stress. Analysis of genes critical to neuronal homeostasis revealed that glucose transporter 3 (GLUT3) mRNA and protein levels were specifically increased in the hippocampus of diabetic rats, while stress had no effect upon GLUT3 expression. Insulin-like growth factor (IGF) receptor expression was also increased in the hippocampus of diabetic rats subjected to stress. In spite of the activation of these adaptive mechanisms, diabetic rats subjected to stress also had signs of neuronal damage and oxidative damage. Collectively, these results suggest that the hippocampus of diabetic rats is extremely susceptible to additional stressful events, which in turn can lead to irreversible hippocampal damage.

Surgical outcome of cervical expansive laminoplasty in patients with diabetes mellitus

STUDY DESIGN

The results from cervical laminoplasty in 18 patients with diabetes mellitus were compared with results from the same procedure in 34 nondiabetic patients matched for age, gender, and disease.

OBJECTIVE

To analyze the effects of diabetes mellitus on the surgical outcome after cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

There have been no reports on the results of cervical laminoplasty patients with diabetes.

METHODS

A retrospective analysis of 18 patients with diabetes mellitus who underwent cervical laminoplasty and 34 nondiabetic patients who underwent the same surgical procedure was undertaken. The postoperative score, intra- and postoperative findings, complications, and radiologic factors were compared between the two groups. In the group with diabetes, the correlation between the recovery rate of the Japanese Orthopedic Association score and the factors indicating the severity of diabetes was assessed.

RESULTS

There was no statistical difference between the total Japanese Orthopedic Association scores of the two groups. However, the group with diabetes mellitus showed a poor recovery of sensory function of the lower extremities. Three patients in the group with diabetes had superficial wound complication after surgery. In contrast, none of the patients in the control group had a wound problem. Furthermore, a negative correlation was observed between the recovery rate and the preoperative HbA1 level in the group with diabetes.

CONCLUSIONS

Although patients with diabetes mellitus who had cervical myelopathy experienced benefits from cervical laminoplasty similar to those of nondiabetic patients, the patients with diabetes were more likely to have wound complication. Furthermore, the negative correlation between the recovery rate and the preoperative HbA1 value might suggest that long-term diabetes control of more than 2 to 3 months before surgery at least is recommended for a favorable surgical outcome.

'Numbness of the feet' is a poor indicator for polyneuropathy in Type 2 diabetic patients

AIMS

To identify neuropathic sensory symptoms associated with a clinical neurological examination (CNE) and to investigate whether these symptoms could be used as a diagnostic or screening tool for diabetic polyneuropathy in general practice.

METHODS

Five hundred and eighty-eight patients with Type 2 diabetes, recruited from 26 general practices in the Netherlands, underwent a CNE and completed a diabetes symptom checklist that included 10 items on neuropathic sensory symptoms. Linear regression analyses were performed to assess the association between neuropathic symptoms and CNE. Receiver operating characteristic (ROC) curves were created to assess the diagnostic properties of neuropathic symptoms.

RESULTS

In this population, with a mean age of 66.8 years, 32% were identified with diabetic polyneuropathy according to the CNE. Variables that showed the strongest association with CNE score were age (beta = 0.41), symptoms of sensory alteration (beta = 0.27), and the item 'numbness of the feet' (beta = 0.35) in particular. ROC curves showed that prediction of diabetic polyneuropathy from these symptoms was unsatisfying. The sensitivity and specificity of daily symptoms of 'numbness of the feet' were 28% and 93%, respectively, in patients <68 years, and 22% and 92%, respectively, in patients > or =68 years.

CONCLUSIONS

Identification of neuropathic sensory symptoms is not useful as a diagnostic or even a screening tool in the assessment of diabetic neuropathy in daily practice. Therefore, the results reported in this paper mandate an annual foot examination by the general practitioner.

Methods for assessing diabetic polyneuropathy: validity and reproducibility of the measurement of sensory symptom severity and nerve function tests

The usefulness of sensory symptoms in the assessment of diabetic polyneuropathy is unclear. In the present study, we studied the hypothesis that pain is associated with small nerve fibre function, and that sensory alteration is associated with large nerve fibre function. In addition, we assessed the reproducibility and the ability to detect changes in clinical status over time of the nerve function tests currently used in clinical trials. Patients (78) with stable diabetic polyneuropathy were examined on three separate occasions with a test-retest interval of 17 and 52 weeks. Small nerve fibre function was measured using temperature discrimination thresholds for warmth (TDTwarmth) and cold (TDTcold). Large nerve fibre function was measured by testing sensory and motor nerve conduction velocities (SNCV and MNCV) and vibration perception thresholds (VPT). Neuropathic pain was only significantly associated with TDTcold, and with the MNCV of the tibial nerve. Sensory alteration was associated with almost all nerve function tests except the SNCV and MNCV of the ulnar nerve. The measurements of symptom severity and the nerve function tests all proved to be sufficiently reproducible. The standardized smallest detectable difference on group level (SDD) of the measurement of sensory alteration and neuropathic pain were almost the same (9% and 12%, respectively). Among the nerve function tests, the SNCV and MNCV had the smallest SDD (3-4%), and were, therefore, potentially the most responsive instruments. The SDD of the TDT was greater than the VPT (9-14% vs 21-28%, respectively). In conclusion, neuropathic pain was not associated with small nerve fibre function, and sensory alteration was associated with both large and small fibre function. In addition, the standardized measurement of symptom severity, the SNCV and MNCV tests, and the VPT test appear to be useful for monitoring the course of polyneuropathy in clinical trials.

Dysfunction of small myelinated afferents in diabetic polyneuropathy, as assessed by laser evoked potentials

OBJECTIVE

To verify whether laser evoked potentials are useful in assessing the function of small afferent fibers and to compare dysfunction of large and small afferent fibers in patients with diabetic polyneuropathy.

METHODS

The brain potentials evoked by CO2 laser stimulation of the hand and foot were studied in diabetic patients (n = 45) with various degrees of peripheral nerve damage. Laser evoked potentials (which assess the function of small myelinated afferents) were also compared with ulnar and sural nerve sensory action potentials (which assess the function of large myelinated afferents) by scoring the abnormalities of the two neurophysiological tests with similar criteria.

RESULTS

Laser evoked potentials were often absent; the mean latency was normal and mean amplitude decreased, as expected in axonopathies. Although clinical examination showed more frequent impairment of vibratory than pinprick sensation, laser evoked potentials and sensory action potentials yielded similar abnormality scores and showed a strong intra-individual correlation.

CONCLUSIONS

Laser evoked potentials, possibly better than standard clinical examination for assessing the abnormalities of small-diameter afferents, indicate that diabetic polyneuropathy induces large- and small-afferent dysfunction in parallel.

ABT-627, an endothelin ET(A) receptor-selective antagonist, attenuates tactile allodynia in a diabetic rat model of neuropathic pain

Tactile allodynia, the enhanced perception of pain in response to normally non-painful stimulation, represents a common complication of diabetic neuropathy. The activation of endothelin ET(A) receptors has been implicated in diabetes-induced reductions in peripheral neurovascularization and concomitant endoneurial hypoxia. Endothelin receptor activation has also been shown to alter the peripheral and central processing of nociceptive information. The present study was conducted to evaluate the antinociceptive effects of the novel endothelin ET(A) receptor-selective antagonist, 2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N, N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid (ABT-627), in the streptozotocin-induced diabetic rat model of neuropathic pain. Rats were injected with 75 mg/kg streptozotocin (i. p.), and drug effects were assessed 8-12 weeks following streptozotocin treatment to allow for stabilization of blood glucose levels (>/=240 mg/dl) and tactile allodynia thresholds (</=8.0 g). Systemic (i.p.) administration of ABT-627 (1 and 10 mg/kg) was found to produce a dose-dependent increase in tactile allodynia thresholds. A significant antinociceptive effect (40-50% increase in tactile allodynia thresholds, P<0.05) was observed at the dose of 10 mg/kg, i.p., within 0.5-2-h post-dosing. The antinociceptive effects of ABT-627 (10 mg kg(-1) day(-1), p.o.) were maintained following chronic administration of the antagonist in drinking water for 7 days. In comparison, morphine administered acutely at a dose of 8 mg/kg, i.p., produced a significant 90% increase in streptozotocin-induced tactile allodynia thresholds. The endothelin ET(B) receptor-selective antagonist, 2R-(4-propoxyphenyl)-4S-(1, 3-benzodioxol-5-yl)-1-(N-(2, 6-diethylphenyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxy lic acid (A-192621; 20 mg/kg, i.p.), did not significantly alter tactile allodynia thresholds in streptozotocin-treated rats. Although combined i.p. administration of ABT-627 and A-192621 produced a significant, acute increase in tactile allodynia thresholds, this effect was significantly less than that produced by ABT-627 alone. These results indicate that the selective blockade of endothelin ET(A) receptors results in an attenuation of tactile allodynia in the streptozotocin-treated rat.

Diabetic neuropathies: features and mechanisms

Diabetic neuropathies include both focal neuropathies and diffuse polyneuropathy. Polyneuropathy, the most common of the diabetic neuropathies excluding focal entrapment, has not yet been explained by a single disease mechanism despite intensive investigation. A number of abnormalities appear to cascade into a 'vicious cycle' of progressive microvascular disease associated with motor, sensory and autonomic fiber loss. These abnormalities include excessive polyol (sugar alcohol) flux through the aldose reductase pathway, functional and structural alterations of nerve microvessels, nerve and ganglia hypoxia, oxidative stress, nonspecific glycosylation of axon and microvessel proteins, and impairment in the elaboration of trophic factors critical for peripheral nerves and their ganglia. While an initiating role for nerve ischemia in the development of polyneuropathy has been proposed, the evidence for it can be questioned. The role of sensory and autonomic ganglia in the development of polyneuropathy has had relatively less attention despite the possibility that they may be vulnerable to a variety of insults, particularly neurotrophin deficiency. Superimposed on the deficits of polyneuropathy is the failure of diabetic nerves to regenerate as effectively as nondiabetics. Polyneuropathy has not yet yielded to specific forms of treatment but a variety of new trials addressing plausible hypotheses have been initiated. This review will summarize some of the clinical, pathological and experimental work applied toward understanding human diabetic neuropathy and will emphasize ideas on pathogenesis.

Chronic inflammatory demyelinating polyneuropathy in diabetics: motor conductions are important in the differential diagnosis with diabetic polyneuropathy

OBJECTIVE

It is important to recognize CIDP occurring in diabetics because, unlike diabetic polyneuropathy, it is treatable. The aim of this study was to find out whether there are clues which help to differentiate CIDP in diabetics from diabetic polyneuropathy.

METHODS

We compared the electrophysiological and pathological findings of 7 diabetics, who developed a predominantly motor polyneuropathy with the features of CIDP, with a group of diabetics referred for symptomatic polyneuropathy.

RESULTS

Of the 7 diabetics we believe developed CIDP, 6 met at least 3 and one patient two of the 4 electrophysiological criteria of demyelination. Of the 100 patients referred for diabetic polyneuropathy, only 4 fulfilled two criteria and none 3. Nerve biopsy findings were not helpful in differential diagnosis, as segmental demyelination and remyelination, onion bulbs and inflammatory infiltrates, which are the histologic features of CIDP, were also present in diabetic polyneuropathy.

CONCLUSIONS

CIDP can be diagnosed in a diabetic patient when motor symptoms are predominant, are more severe than expected in diabetic polyneuropathy and 3 of the 4 electrophysiological criteria for demyelination are fulfilled. When only two criteria are met, we believe that a trial with one of the established treatments for CIDP may be helpful in confirming the diagnosis.

Effects of ALCAR on the fast axoplasmic transport in cultured sensory neurons of streptozotocin-induced diabetic rats

The effects of acetyl-L-carnitine (ALCAR) on fast axoplasmic transport were studied in cultured dorsal root ganglion (DRG) neurons of diabetic rats. Three-month-old male rats were used 7 days after streptozotocin injection. Neurons obtained from ganglia were cultured with a high concentration of glucose. The amount and the mean velocity of retrogradely transported particles, reduced in the diabetic animal, were transiently recovered by 1 mM ALCAR. The number of particles moving at 0.8-1.2 microm/s, considered to be lysosomes, increased in the velocity distribution. ALCAR did not modify the amount and mean velocity of anterograde particles which were unaffected by diabetes, or of bidirectional particles in neurons of control rats. This study suggests that diabetic neuropathy may be relieved by ALCAR via recovering retrograde axoplasmic transport.

An adenosine kinase inhibitor attenuates tactile allodynia in a rat model of diabetic neuropathic pain

The present study was conducted to characterize the development of tactile allodynia in the streptozotocin-induced rat model of diabetes, and to evaluate the antinociceptive effects of systemically administered morphine and the adenosine kinase inhibitor, 5'-deoxy-5-iodotubercidin (5'd-5IT) in this model. Rats were injected with 75 mg/kg streptozotocin (i.p.), and blood glucose levels were determined 3-4 weeks later. Diabetic (blood glucose levels > or = 250 mg/dl) and vehicle-injected rats were examined weekly for the development of tactile allodynia by measuring the threshold for hind paw withdrawal using von Frey hairs. Withdrawal thresholds were reduced to 6.8+/-0.6 g (mean+/-S.E.M.) in approximately one-third of streptozotocin-treated rats 7 weeks after streptozotocin treatment as compared to control thresholds (13.2+/-0.1 g), and this allodynia persisted for at least an additional 7 weeks. In additional experiments, morphine sulfate (5-21 micromol/kg, i.p.) produced dose-dependent antinociceptive effects on tactile allodynia for up to 2 h post-dosing. The adenosine kinase inhibitor, 5'd-5IT (2.5 and 5 micromol/kg, i.p.) also dose-dependently attenuated tactile allodynia. Pretreatment with the opioid receptor antagonist, naloxone (27 micromol/kg, i.p.) or the non-selective adenosine receptor antagonist, theophylline (111 micromol/kg, i.p.) significantly diminished the anti-allodynic effects of morphine and 5'd-5IT, respectively. The present study demonstrates that the potent and selective adenosine kinase inhibitor, 5'd-5IT, is equally effective as morphine in blocking tactile allodynia in this model.

Subclinical neuropathy in type I diabetic children

OBJECTIVES

Small and large, somatic and autonomic nerve fibre functions were neurophysiologically evaluated in 33 asymptomatic neurologically free type I diabetic children and 69 age-matched healthy controls.

METHODS

The evaluation of large and small somatic nerve fibre function was performed by conventional nerve conduction studies, thermal specific and thermal pain sensitivity tests, as well as autonomic nerve fibre functions by sympathetic skin response and R-R interval variation assessment.

RESULTS

A significant difference was established between the healthy and the diabetic group. Neurophysiologically determined subclinical neuropathy was found in 87% of type I diabetic children. The majority of abnormal recordings were found on the lower limbs. The dysfunction of the somatic motor large nerve fibre type in the lower limbs was altered in 57% of patients, somatic sensory large in 39%, somatic sensory small in 45%, and sympathetic in 45%. The leading abnormal measure was a delayed sympathetic skin response on the foot (42% of diabetic children) followed by a reduced amplitude of sural nerve action potential (36%). The whole spectrum of recordings showed scattered involvement of nerve functions. There was no selective susceptibility of nerve fibre types exposed to a noxious factor.

CONCLUSION

A complex neurophysiological assessment, including standard nerve conduction studies as well as psychophysical examination and autonomic nerve function tests, evaluating the function of small and large nerve fibres, is recommended for evaluating the subclinical neuropathy in asymptomatic type I diabetic children.

Effects of streptozotocin-induced diabetes on heart rate, blood pressure and cardiac autonomic nervous control

Diabetes-associated alterations in resting heart rate and blood pressure have been demonstrated in clinical studies and in animal models of insulin-dependent diabetes mellitus (IDDM). These alterations may result from changes in the heart, vasculature or autonomic nervous system control. Using the streptozotocin- (STZ-) treated rat model of IDDM, the current study was designed to: (1) monitor changes in heart rate and blood pressure continually during a 10-week period in conscious unrestrained animals; and (2) determine if observed alterations in heart rate were mediated by changes in sympathetic and/or parasympathetic nervous control. Biotelemetry techniques were used. Heart rate and blood pressure were recorded 24 h a day at 10 min intervals before and after induction of diabetes. Diabetes was induced by i.v. administration of 50 mg/kg STZ. Resting autonomic nervous system tone was estimated by chronotropic responses to full-blocking doses of nadolol (5 mg/kg i.p.) and atropine (10 mg/kg i.p.). STZ-induced diabetes was associated with time-dependent reductions in heart rate and its circadian variation. Diastolic blood pressure and mean arterial pressure did not differ significantly when compared between control and STZ-treated animals; however, pulse pressure was diminished in diabetic rats. Chronotropic responses to both nadolol and atropine were blunted significantly in diabetic animals suggesting that resting levels of both vagal and sympathetic nervous tone to the heart were diminished. Heart rate in the presence of both nadolol and atropine was also decreased in diabetic rats. All effects observed following administration of STZ were reversed, at least in part, by insulin treatment. These results suggest that IDDM is associated with time-dependent reductions in resting heart rate and autonomic nervous control of cardiac function.

Normal distributions of thermal and vibration sensory thresholds

The distributions of sensory thresholds were estimated in a healthy population while controlling for potential covariates. Using the method of levels and the two-alternative forced choice, thermal and vibration thresholds respectively were measured in the hand and foot of 148 subjects. Age was uniformly distributed between 20 and 86 years. Independent effects of age, gender, height, and skin temperature were estimated using multiple linear regression. Parametric and nonparametric methods were used to estimate the distributions of interest. Significant age-related increases were observed for all vibration thresholds (P < 0.0001), and for thermal thresholds in the foot (P < 0.0002). Percentiles were estimated for thermal thresholds in the hand and age-adjusted continuous distributions were calculated for all other thresholds. Height was positively associated with vibration thresholds in the foot (P < 0.003), and appropriate corrections were made. Our results provide reference values for thermal and vibration sensory thresholds in a healthy population, allowing for the accurate diagnosis of disordered sensory function.

Lamotrigine in the treatment of painful diabetic neuropathy

An open trial was conducted to study the potential efficacy of lamotrigine, a novel antiepileptic agent that blocks voltage-sensitive sodium channels and inhibits the release of glutamate, in relieving the pain associated with diabetic neuropathy. Subsequent to a 1 week washout period from previous analgesics, lamotrigine was administered at a dose of 25 mg/day for 1 week. The dose was doubled on a weekly basis up to 400 mg/day over 6 weeks. The McGill pain questionnaire (MPQ), spontaneous pain and a series of mechanical and thermal stimuli-induced pain were measured with the use of 0-100 visual analogue scale (VAS), on seven office visits. Pain level was also recorded by each patient twice daily, 1 week before, during, and 2 weeks after the treatment period with the use of a 0-10 numerical pain scale (NPS). Quantitative mechanical (Von Frey filaments) and thermal testing (QTT), and routine blood tests were performed at the beginning and at the end of the study. Thirteen patients completed the study. Spontaneous pain measured by VAS and NPS gradually dropped from a baseline of 49 +/- 8 and 6.8 +/- 0.6, to 20 +/- 8.6 (p < 0.001) and 4.3 +/- 0.9 (p < 0.001), respectively, at the end of the treatment period. Similarly, cold allodynia dropped from 38 +/- 9.2 to 16 +/- 15.3 (p = 0.01), and the MPQ score from 13.6 +/- 0.8 to 11.0 +/- 1.5 (p < 0.01). In contrast, no significant changes were found in the QTT, mechanical pain thresholds and laboratory results. Two patients were withdrawn from the study because of adverse effects. A long-term follow up showed that most patients were still using lamotrigine 6 months after the end of the study. The results of the study suggest that lamotrigine is potentially effective and safe in treating painful diabetic neuropathy. Copyright Rapid Science Ltd

Acupuncture for the treatment of chronic painful peripheral diabetic neuropathy: a long-term study

Forty-six diabetic patients with chronic painful peripheral neuropathy were treated with acupuncture analgesia to determine its efficacy and long-term effectiveness. Twenty-nine (63%) patients were already on standard medical treatment for painful neuropathy. Patients initially received up to six courses of classical acupuncture analgesia over a period of 10 weeks, using traditional Chinese Medicine acupuncture points. Forty-four patients completed the study with 34 (77%) showing significant improvement in their primary and/or secondary symptoms (P < 0.01). These patients were followed up for a period of 18-52 weeks with 67% were able to stop or reduce their medications significantly. During the follow-up period only eight (24%) patients required further acupuncture treatment. Although 34 (77%) patients noted significant improvement in their symptoms, only seven (21%) noted that their symptoms cleared completely. All the patients but one finished the full course of acupuncture treatment without reported or observed side effects. There were no significant changes either in the peripheral neurological examination scores, VPT or in HbA1c during the course of treatment. These data suggest that acupuncture is a safe and effective therapy for the long-term management of painful diabetic neuropathy, although its mechanism of action remains speculative.

Diabetes-induced suppression of IGF-1 and its receptor mRNA levels in rat superior cervical ganglia

Insulin-like growth factor-I (IGF-I) is implicated in the development, survival and maintenance of function of sympathetic and sensory neurons. These neurons are affected at an early stage during the course of diabetes. Reverse transcriptase polymerase chain reaction (RT-PCR) based assay revealed that rat superior cervical ganglia (SCG) express mRNA transcripts for IGF-I and its receptor. Moreover, specific membrane protein binding sites for IGF-I within the SCG have also been demonstrated using competition-inhibition and affinity cross-linking techniques. An induction of diabetes with streptozotocin (STZ, 55 mg/kg, i.v.) produced a marked decrease in the SCG levels of mRNA transcripts for IGF-I and its receptor. Concentrations of circulating IGF-I and its receptor protein within the SCG were also reduced in this disease state. Insulin treatment partially prevented diabetes-related alterations in circulating IGF-I and the SCG-IGF-I system. Overall, the data described in this study may be of value in understanding the pathogenetic mechanism(s) responsible for the development of diabetic sympathetic neuropathy.

Autoimmune diabetic neuropathy

Recent work has shown that inflammatory vasculopathy is commonly seen in biopsies of diabetic patients with neuropathy. Most of these patients have had syndromes consistent with proximal diabetic neuropathy or amyotrophy. This suggests that inflammatory vasculopathy is important in the pathogenesis of these disorders. Immunosuppressive therapy may benefit many of these patients.

Long-term effects of pancreatic transplantation on diabetic neuropathy

Restoration of a long-lasting euglycemic state by a functioning pancreatic transplantation (PTx) is the most logical treatment for insulin-dependent diabetes mellitus and for amelioration of secondary complications, including neuropathy. We evaluated neurological function by clinical examination, nerve conduction studies, and autonomic function tests in 115 patients with a functioning PTx and in 92 control patients treated with insulin, at baseline and 1, 2, 3.5, 5, 7, and 10 years later. In control patients, neuropathy progressively worsened during follow-up. The clinical examination score and composite indices of abnormality of motor and sensory nerve conduction decreased significantly at all intervals tested. Autonomic function indices also decreased, but significantly only after 1 year. In patients who received a successful PTx the neuropathy improved. The motor and sensory nerve conduction indices increased significantly at all intervals after transplantation, whereas the clinical examination and autonomic tests improved only slightly. Patients who received either a PTx alone, a PTx after a kidney graft, or simultaneous pancreatic and kidney transplantations improved similarly over the follow-up. These results indicate that a functioning PTx halts the progression and improves the signs of diabetic polyneuropathy by restoration of a normoglycemic state.

Diabetic neuropathy

The most common form of diabetic neuropathy is chronic, distal symmetrical sensorimotor, or predominantly sensory neuropathy; the latter is invariably associated with some degree of autonomic dysfunction. There are, however, other neuropathic patterns in diabetes mellitus that are uncommon but are important to recognize, since they may mimic many other non-neurologic diseases. This article discusses a variety of forms of mononeuropathies and diabetic proximal motor neuropathy, commonly known as diabetic amyotropy.

Demographic and clinical features of diabetes mellitus in 1095 Yemeni patients

The ever-increasing incidence of diabetes mellitus is a cause for growing public health concern in both developed and developing countries. In this study, we aim to explore the special demographic and clinical features of diabetes, as seen in a large sample of Yemeni patients, and to compare these features with those reported in other countries. All patients referred to our diabetic clinic over a five-year period were investigated according to a standardized protocol. Data was collected and fed into a personal computer with a software statistical package for analysis. The relative frequencies of clinical classes of diabetes were 10.5% for IDD, 58.6% for non-obese NIDDM; 26.2% for obese NIDDM, and 4.7% for IGT. In the IDDM class, the age-specific relative frequency rate showed a higher and earlier onset peak frequency in females than in males. Among NIDDM class, about 31% of patients were diagnosed under the age of 45 years, and only 12% were first diagnosed after the age of 65 years. Most NIDDM patients came from social classes I and II (professionals and intermediate professionals) and most IDDM patients came from social class IIIM (skilled manual). A positive family history of diabetes among first-degree relatives of index patients was observed in 33.7% of IDDM patients, in 30% of non-obese NIDDM patients, in 39.2% of obese NIDDM patients and 32% of IGT patients. Female NIDDM patients had a significantly higher mean body mass index (BMI) than males (P<0.0001). Hypertension was recognized in 24.2% of the diabetic population aged 20 to A(3) 65 years. Large vessel disease (LVD) was observed in 28% of patients, small vessel disease (SVD) in 45%, and peripheral neuropathy in 40.7%. Inadequate glycemic control was noticed during follow-up in the majority of patients. Diabetes mellitus in Yemen, especially NIDDM, is characterized by an earlier age at onset, and predominance of males and non-obese NIDM subclass. Other characteristics include moderate genetic susceptibility, inadequate glycemic control and high prevalence of chronic complications.

Outcome of carpal tunnel release surgery in patients with diabetes

The surgical outcomes in 149 patients with diabetes and carpal tunnel syndrome who underwent transverse carpal ligament release surgery are reported. Associated factors such as insulin dependence, length of time with diabetes, electrodiagnostic studies, severity of neurological deficit, presence of polyneuropathy, and cervical disc disease were considered. Analysis of preoperative and postoperative symptoms, clinical findings, diagnostic studies, and patient self-assessment indicated that the majority of patients with diabetes experienced a favorable surgical outcome, regardless of any associated factors. Eighty-four percent of the patients reported good to excellent postoperative results in their hands. Further analysis of the subpopulation of insulin-dependent diabetics showed that 81% experienced good to excellent postoperative results. These results compare favorably with those of the control group: 200 nondiabetic patients, of whom 90% rated their results from carpal tunnel release surgery as good to excellent. There were no major complications in any group.

Duodenal complications in bladder-drained pancreas transplantation

BACKGROUND

The most common type of pancreas transplantation is whole pancreaticoduodenal (with bladder drainage) from a cadaver donor. Complications can arise not only from the pancreas itself but also from the simultaneously transplanted duodenum. The purpose of this study was to analyze the incidence, diagnosis, and treatment of duodenal complications and their impact on patient and pancreas graft survival rates.

METHODS

Our retrospective study is based on 425 pancreaticoduodenal transplantations performed between July 1, 1986, and June 30, 1994. Complications pertaining to the duodenal segment were labeled early if they occurred within the first postoperative month and late otherwise. Mean follow-up was 55 months (range, 13 to 108 months).

RESULTS

We noted 85 (20%) duodenal complications: duodenal leaks (n = 42), hematuria (n = 26), recurrent urinary tract infections (n = 9), duodenal ulceration or necrosis (n = 6), and bladder stones (n = 2). Of these complications, 40 (48%) required surgical intervention. In all, duodenal complications resulted in 14 (16%) enteric conversions and eight (9%) pancreas graft losses (six because of duodenal leak and 2 because of hematuria). The mortality rate from duodenal complications was 0%.

CONCLUSIONS

Duodenal complications were common, but they were not associated with a high rate of pancreas graft loss (only 9%). With early diagnosis and treatment, morbidity can be reduced and death avoided in pancreas transplant recipients.

Endogenous mono-ADP-ribosylation in retina and peripheral nervous system. Effects of diabetes

The extranuclear endogenous mono-ADP-ribosylation of proteins was monitored in cellular preparations of retina, superior cervical ganglion, dorsal root ganglia and peripheral nerve. At least 6 protein fractions are ADP-ribosylated in the crude extract fraction from retina control preparations, while in diabetic rats the number of retina labeled proteins and the extent of labeling are highly reduced. In the superior cervical ganglion labeling was present in 10 proteins, in diabetics it was greatly decreased. Treatment of diabetic rats with silybin, a flavonoid mono-ADP-ribosyltransferase inhibitor, did not affect hyperglycemia, but prevented the alteration of extent of protein ADP-ribosylation. These data suggest that proteins of retina and peripheral ganglia are excessively ADP-ribosylated in vivo. The effects of silybin treatment on excessive mono-ADP-ribosylation of proteins was associated with the prevention of reduction of substance P-like immunoreactivity levels, that is typical of diabetic neuropathy. In the membrane fraction of sciatic nerve Schwann cells, at least 9 proteins were ADP-ribosylated, diabetes caused a marked increase of labeling. A comparable increase involving the same proteins is triggered by chronic nerve injury and by corticosteroid treatment. Silybin treatment of diabetic rats prevented such an increase. We propose that the inhibition of excessive protein mono-ADP-ribosylation by silybin prevented the onset of diabetic neuropathy. While the effects on Schwann cells is likely indirect and secondary to the improvement of diabetic axonopathy.

Profile of neurological problems in diabetes mellitus retrospective analysis of data from 1294 patients

Data from 1294 patients with diabetes mellitus admitted to the Endocrinology Department of the Institute of Medical Sciences, Srinagar, Kashmir, from 1986 to 1994, were analyzed for frequency of various neurological problems. Of 1294 patients, 46.29% had clinical evidence of one or more neurological problems. The frequency of neurological problems was significantly more in patients with type II diabetes mellitus (P<0.001). Predominant neurological problems included peripheral neuropathy (96.66%), stroke (5.51%), Parkinsonism (1.50%), seizure disorder (1.17%) and dementia (1%). Mean (+/- SD) age of patients with neurological problems was significantly more (P<0.001) than those without neurological problems (52.07+/- 9.52 versus 47.45+/- 12.87 years for type II diabetes mellitus; 26.73+/- 8.40 versus 18.0+/- 3.62 for type I diabetes mellitus). Mean duration of diabetes in patients with neurological problems was significantly more than those without neurological problems (6.70+/- 6.04 versus 3.95+/- 4.22 years for type II diabetes mellitus; 5.63+/- 3.67 versus 1.89+/- 2.57 for type I diabetes mellitus). At the time of admission, fasting blood glucose was lower in patients without neurological problems as compared to patients with problems (9.08+/- 2.22 versus 11.05+/- 4.91 mmol/L for type II diabetes mellitus; 9.44+/- 2.80 versus 13.01+/- 5.01 mmol/L for type I diabetes mellitus; P7lt;0.001).

Chronic inflammatory demyelinating polyneuropathy (CIDP) in diabetics

Seven diabetic patients developed a progressive, moderately severe, motor rather than sensory neuropathy predominantly affecting the legs. This met clinical and electrophysiological criteria for chronic inflammatory demyelinating polyneuropathy (CIDP). Nerve biopsies showed a variety of abnormalities, none of which clearly distinguished between diabetic polyneuropathy and CIDP. The patients were treated with combinations of corticosteroids, azathioprine, plasmapheresis and intravenous immune globulin; all improved substantially. We believe that CIDP may masquerade as unusually severe and progressive diabetic distal symmetric polyneuropathy. It is important to recognize CIDP in diabetics because, unlike diabetic polyneuropathy, CIDP is treatable.

Alterations of protein mono-ADP-ribosylation and diabetic neuropathy: a novel pharmacological approach

This study monitored the extranuclear endogenous mono ADP-ribosylation of proteins. At least 10 proteins were ADP-ribosylated in a crude extract from control superior cervical ganglia, and 7 were labeled in control dorsal root ganglia; whereas in the diabetic rat the extent of labeling was reduced. These data suggest that proteins of peripheral ganglia are excessively ADP-ribosylated in vivo. Treatment of diabetic animals with silybin, a flavonoid with ADP-ribosyltransferase inhibitory activity, did not affect hyperglycemia, but prevented the alterations in the extent of mono-ADP-ribosylation of proteins. This effect was associated with the prevention of substance P-like immunoreactivity loss in the sciatic nerve. In the membrane fraction of sciatic nerve Schwann cells, at least 9 proteins were ADP-ribosylated, in diabetic rats the extent of labeling was increased. A comparable increase involving the same proteins was triggered by chronic nerve injury and by corticosteroid treatment. Silybin treatment of diabetic rats prevented such an increase. We propose that the inhibition of excessive protein mono-ADP-ribosylation by silybin prevented the onset of diabetic neuropathy, while the silybin effect on mono-ADP-ribosylation of Schwann cells is likely indirect and secondary to the improvement of diabetic axonopathy.

[Electrophysiologic study, diagnosis and cases of acquired sensory polyneuropathy]

Sensory neuropathies encompass a group of neuropathies affecting solely or predominantly peripheral sensory nerves. They are rarely encountered in clinical practice. The authors review sensory nerve conduction studies and compare the various recording technics. Values of compound sensory action potential amplitude and sensory nerve conduction velocity are analyzed. On the basis of clinical and electrophysiological sensory impairment, three types of neuropathies can be proposed: neuropathies with either large, small or total myelinated fibers involvement. Lastly definable causes of sensory neuropathies are reviewed.

Peripheral neuropathy and peripheral nerve injury

The peripheral nerves to the bladder can be altered by several disease processes. Voiding symptoms alone are not reliable in predicting the exact neurogenic bladder dysfunction. Urodynamic evaluation is crucial to optimize therapy and to rule out concomitant pathology.

AAEM case report #13: diabetic amyotrophy

A case fulfilling the criteria for the diagnosis of diabetic amyotrophy is reported. Based on the clinical and electrodiagnostic features, it is concluded that diabetic amyotrophy is a recognizable clinical entity that can be differentiated from other diabetic neuropathies. The site of the lesion and the pathogenesis in diabetic amyotrophy remain controversial. The course of the illness is variable with gradual, but often incomplete, improvement.

Nerve conduction studies in adrenomyeloneuropathy

OBJECTIVE

Adrenomyeloneuropathy (AMN) is an X linked metabolic disorder presenting with progressive spastic paraparesis in the third to fifth decade of life. Although peripheral neuropathy is also present in most patients, prominent pyramidal signs may make its clinical recognition difficult. The objective was to characterise the peripheral neuropathy in patients with AMN by nerve conduction studies.

METHODS

Nerve conduction studies were performed in 99 men known to have AMN and in 38 heterozygous women, all of whom had neurological disabilities.

RESULTS

Of the 13 variables obtained, at least one was abnormal in 82% of patients. The abnormalities were more common in men than in women (87% v 67%); in legs than in arms (77% v 38%); in motor than in sensory conduction (80% v 39%); and in latency (distal and F wave) and velocity compared with amplitude (80% v 29%). Twenty six patients had at least one nerve variable value in the demyelinating range. Four variables (sural velocity, peroneal amplitude, peroneal velocity, and peroneal F wave) were correlated with the expanded disability status scale; five variables (peroneal velocity, tibial H reflex, median distal latency, median conduction velocity, and median F wave latency) were correlated with serum very long chain fatty acids (VLCFAs); and two variables (sural amplitude and peroneal distal latency) were more likely to be abnormal in patients with normal adrenal function than in patients with Addison's disease.

CONCLUSIONS

Nerve conduction studies in patients with AMN are often abnormal and suggest a mixture of axonal loss and multifocal demyelination. Their correlation with disability status and serum VLCFAs suggests that measures from nerve conduction studies may be useful in evaluating future treatments.

Effect of steroids on CSF matrix metalloproteinases in multiple sclerosis: relation to blood-brain barrier injury

Contrast-enhanced MRI in patients with MS shows that increased permeability of the blood-brain barrier (BBB) commonly occurs. The changes in capillary permeability often precede T2-weighted MRI evidence of tissue damage. In animal studies, intracerebral injection of the matrix metalloproteinase (MMP) 72-kDa type IV collagenase (gelatinase A) opens the BBB by disrupting the basal lamina around capillaries. Steroids affect production of endogenous MMPs and tissue inhibitors to metalloproteinases (TIMPs). To determine the role of MMP activity in BBB damage during acute exacerbations of MS, we measured MMPs in the CSF of patients with MS. Patients (n = 7) given steroids to treat an acute episode of MS had CSF sampled before and after 3 days of methylprednisolone (1 g/day). Patients had a graded neurologic examination and gadolinium-enhanced MRI before treatment. CSF studies included total protein, cell count, and a demyelinating profile. We measured levels of MMPs, urokinase-type plasminogen activator (uPA), and TIMPs by zymography, reverse zymography, and Western blots. The MMP, 92-kDa type IV collagenase (gelatinase B), fell from 216 +/- 70 before steroids to 54 +/- 26 relative lysis zone units (p < 0.046) after treatment. Similarly, uPA dropped from 3880 +/- 800 to 2655 +/- 353 (p < 0.03). Four patients with gadolinium enhancement on MRI had the most pronounced drop in gelatinase B and uPA. Western immunoblots showed an increase in a complex of gelatinase B and TIMPs after treatment, suggesting an increase in a TIMP (p < 0.05). Reverse zymography of CSF samples showed that steroids increased a TIMP with a molecular weight similar to that of mouse TIMP-3 (p = 0.053). Our results suggest that increased gelatinase B is associated with an open BBB on MRI. Steroids may improve capillary function by reducing activity of gelatinase B and uPA and increasing levels of TIMPs.

Diabetic peripheral neuropathy: a clinicopathologic and immunohistochemical analysis of sural nerve biopsies

We performed quantitative immunohistochemical studies of sural nerve biopsy specimens from 20 patients to determine whether endoneurial and epineurial lymphocytic infiltration occurs in diabetic nerves. The diabetic nerves contained a mean of 129 CD3+ cells per tissue section compared to 19 cells in patients with chronic neuropathy matched for the histologic severity of disease, and 0-5 cells in normal control nerves. The T-cell infiltrates in the diabetic nerves were predominantly of the CD8+ cell type. Activated endoneurial lymphocytes expressed immunoreactive cytokines and major histocompatibility class II antigens. Microvasculitis was found in 12 (60%) patients. Infiltrative T cells may contribute to the pathogenesis of diabetic neuropathy through a variety of effector mechanisms.

Structure-function relationships within peripheral nerves in diabetic neuropathy: the hydration hypothesis

To define the quantitative relationship between peripheral nerve structure and function imposed by endoneurial oedema in the diabetic state, we determined values for sural nerve hydration structure as measured by magnetic resonance spectroscopy, and for neurological function with scores for nerve conduction properties (NCV-score), neuropathic symptoms (NS-score), and examination signs (NE-score). The coefficient of sural nerve hydration was elevated to 30 +/- 6% (p < 0.05) in 79 symptomatic neuropathic diabetic subjects with an average of 15 years of diabetes mellitus, compared to a value of 25 +/- 3% in 72 non-diabetic control subjects. In contrast, in 75 asymptomatic diabetic subjects with an average of 6 additional years of diabetes, the mean hydration coefficient was only 28 +/- 5% (p < 0.05). A nerve hyperhydration state was identified with a prevalence of 25% within the asymptomatic group characterized by nerve hydration greater than the 95th percentile, early changes in nerve electrophysiology and neurological examination, but with no symptomatology of neuropathy. Stratification of the symptomatic neuropathic group by worsening nerve electrophysiology, demonstrates a coincident deterioration in neurological examination (RR = 5.39 at maximum NCV-score), and neuropathy symptomatology (RR = 4.80 at maximum NE-score). The present data are consistent with the hypothesis that endoneurial oedema initiates deterioration sequentially in nerve electrophysiology, followed by abnormal findings on neurological examination, preceding the patient's final perception of symptomatic stocking glove peripheral diabetic neuropathy.

Management of diabetic pregnancy complicated by coronary artery disease and neuropathy

Various manifestations of diabetic neuropathy may complicate pregnancies of young diabetic patients. Of all forms of diabetic neuropathy, autonomic neuropathy, and, in particular, gastropathy, may cause the most devastating complications. Because neuropathy is a common abnormality in young asymptomatic diabetic women, screening for this disorder may be advisable and can be accomplished by relatively simple and noninvasive tests. Screening is best performed before conception or early in pregnancy, because pregnancy itself and its possible complications later modify the autonomic nervous function tests and make testing unreliable. Practitioners and obstetricians who provide care and counseling to young diabetic patients should be familiar with the risks and consequences to maternal and fetal health that may be imposed by the different forms of neuropathy. Moderate-to-severe autonomic dysfunction may be considered a relative contraindication to pregnancy, especially if gastropathy is part of the clinical presentation. The management dilemmas and high mortality and morbidity associated with symptomatic diabetic neuropathy may justify the addition of a new independent class, class N (neuropathy), to the current classification systems for diabetes in pregnancy.

Treatment of diabetic polyneuropathy with the neurotrophic peptide ORG 2766

The efficacy of the neurotrophic peptide ORG 2766 in diabetic patients with polyneuropathy was evaluated in a double-blind, placebo-controlled, multicentre trial. One hundred and twenty four patients were randomised in five groups to receive 0.1, 0.4, 2 or 5 mg ORG 2766 or placebo, once daily, administered subcutaneously 52 weeks. Thermal discrimination thresholds (TDT) and vibration perception thresholds (VPT), motor and sensory nerve conduction velocity, Hoffmann reflex, heart rate variation during deep breathing and heart rate response after standing up, neurological examination score and neuropathic symptom score were determined at baseline and after 17, 34 and 52 weeks of treatment. Of the nerve function indices studied, at week 52 the TDTwarmth of the hand in the ORG 2766 0.1, 0.4 and 5 mg groups and the TDTcold of the foot in the ORG 2766 0.1 and 0.4 mg groups significantly improved compared with placebo. Further significant improvement as compared with placebo was observed in the paraesthesia score at week 34 and week 52 in the ORG 2766 2 mg group. Only at week 34 had both the heartbeat variation during deep breathing and the VPT of the foot in the ORG 2766 0.1 mg group improved significantly, compared with placebo. No further statistically significant differences were observed at time for the other measures. No adverse reactions were observed. The only recorded drug-induced side effect was pain at the injection site. Taking all measures of efficacy into account, the statistically significant results observed did not show consistency within each measure. Therefore, it is concluded that ORG 2766, in contrast to earlier reports, is not effective in treating diabetic polyneuropathy.

Central motor conduction time in children and adolescents with insulin-dependent diabetes mellitus (IDDM)

Measurement of central motor conduction time (CMCT) after percutaneous magnetic stimulation of the brain is an electrophysiological method that may discover subclinical impairment of central nervous system (CNS). In order to detect an impairment of CNS, we measured CMCT right (R) and left (L) after percutaneous stimulation of the brain in 34 patients affected by insulin-dependent diabetes mellitus (IDDM) (16 males and 18 females), aged 16.4 +/- 4.1 years (7.3-23.2 years), with duration of disease 7.6 +/- 4.9 years (7/12-16 years), and HbA1c annual mean 7.41 +/- 1.1% (n.v. 5.14 +/- 0.84%). Twenty-three sex- and age-matched healthy subjects served as controls. In our IDDM patients we observed a delay of CMCT R (P < 0.0005) and L (P < 0.0005) as compared to controls. No correlation was found between CMCT (R and L) and chronologic age, duration of disease, peroneal motor nerve conduction velocity. No association was observed between CMCT (R and L) and HLA antigens. On the basis of IDDM duration, patients were divided into 2 groups (G): G I (9 pts) with IDDM < 2 years and G II (25 pts) with IDDM > 5 years, 12 of them with precocious signs of one or more microangiopathic complications. No difference in CMCT (R and L) was observed between the 2 groups and between G I and controls; G II patients had a longer delay of CMCT R (P < 0.0001) and L (P < 0.0001) than controls. In G II patients, a positive correlation between CMCT R and HbA1c of the 5 years before the test (P < 0.025) was also observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetic neuropathy in the rat: 1. Alcar augments the reduced levels and axoplasmic transport of substance P

This study examined the sciatic nerve axonal transport of substance P-like immunoreactivity (SPLI) and its basal content in stomach, sciatic nerve and lumbar spinal cord of 8- and 12-week alloxan-diabetic rats, respectively. One group of diabetic rats received acetyl-l-carnitine (ALCAR) throughout the experimental period. Alloxan treatment caused hyperglycemia and reduced boy growth. Axonal transport of SPLI was studied by measurement of 24-hour accumulation at a ligature on the sciatic nerve. There was a marked reduction (from 50% to 100% according to the nerve segment examined) of anterograde and retrograde accumulation of SPLI in the constricted nerve of 8-week diabetic rats. In the sciatic nerve of ALCAR-treated diabetic rats, the accumulation of SPLI was comparable to control values. In the sciatic nerve, lumbar spinal cord and stomach of 12-week diabetic rats, there is a significant reduction of SPLI content. ALCAR treatment prevented SPLI loss in these tissues. Sciatic nerves showed the typical sorbitol increase and myo-inositol loss that were significantly counteracted by ALCAR. This study suggests that ALCAR treatment prevents diabetes-induced sensory neuropathy by improving altered metabolic pathways such as polyol activity and myo-inositol synthesis, and by preventing the reduction of synthesis and axonal transport of substance P.