Altered arachidonic acid metabolism via COX-1 and COX-2 contributes to the endothelial dysfunction of penile arteries from obese Zucker rats

BACKGROUND AND PURPOSE

The aim of the current study was to investigate the role of arachidonic acid (AA) metabolism via cyclooxygenase (COX) in the endothelial dysfunction of penile arteries from pre-diabetic, obese Zucker rats (OZR).

EXPERIMENTAL APPROACH

Penile arteries from OZR and from lean Zucker rats (LZR) were mounted in microvascular myographs to assess vascular function and COX expression was determined by immunohistochemistry.

KEY RESULTS

Acetylcholine (ACh) and AA elicited relaxations that were impaired in arteries from OZR. Inhibition of both COX-1 and COX-2 reduced the relaxant effects of ACh and AA in LZR but not in OZR. Inhibitors of COX-1 and of the TXA(2)/PGH(2) (TP) receptor enhanced the relaxations induced by AA in both LZR and OZR, whereas COX-2 inhibition enhanced these responses only in OZR. TP receptor blockade did not restore ACh relaxant responses in arteries from OZR. Inhibition of COX-1 increased basal tension in OZR and this contraction was blunted by TP receptor blockade. The vasoconstrictor responses to noradrenaline were augmented by indomethacin and by COX-2 inhibition in LZR but not in OZR. Immunohistochemical staining showed that both COX-1 and COX-2 are expressed in the endothelium of penile arteries from both LZR and OZR.

CONCLUSIONS AND IMPLICATIONS

Vasoactive prostanoids were formed via constitutively active COX-1 and COX-2 pathways in normal rat penile arteries. Under conditions of insulin resistance, the release and/or effects of vasodilator prostanoids were impaired, contributing to the blunted endothelium-dependent vasodilatation and to the enhanced vasoconstriction.

Neuronal and smooth muscle receptors involved in the PACAP- and VIP-induced relaxations of the pig urinary bladder neck

BACKGROUND AND PURPOSE

As pituitary adenylate cyclase-activating polypeptide 38 (PACAP 38)- and vasoactive intestinal peptide (VIP) are widely distributed in the urinary tract, the current study investigated the receptors and mechanisms involved in relaxations induced by these peptides in the pig bladder neck.

EXPERIMENTAL APPROACH

Urothelium-denuded strips were suspended in organ baths for isometric force recordings and the relaxations to VIP and PACAP analogues were investigated.

KEY RESULTS

VIP, PACAP 38, PACAP 27 and [Ala(11,22,28)]-VIP produced similar relaxations. Inhibition of neuronal voltage-gated Ca(2+) channels reduced relaxations to PACAP 38 and increased those induced by VIP. Blockade of capsaicin-sensitive primary afferents (CSPA), nitric oxide (NO)-synthase or guanylate cyclase reduced the PACAP 38 relaxations but failed to modify the VIP responses. Inhibition of VIP/PACAP receptors and of voltage-gated K(+) channels reduced PACAP 38 and VIP relaxations, which were not modified by the K(+) channel blockers iberiotoxin, charybdotoxin, apamin or glibenclamide. The phosphodiesterase 4 inhibitor rolipram and the adenylate cyclase activator forskolin produced potent relaxations. Blockade of protein kinase A (PKA) reduced PACAP 38- and VIP-induced relaxations.

CONCLUSIONS AND IMPLICATIONS

PACAP 38 and VIP relax the pig urinary bladder neck through muscle VPAC(2) receptors linked to the cAMP-PKA pathway and involve activation of voltage-gated K(+) channels. Facilitatory PAC(1) receptors located at CSPA and coupled to NO release, and inhibitory VPAC receptors at motor endings are also involved in the relaxations to PACAP 38 and VIP, respectively. VIP/PACAP receptor antagonists could be useful in the therapy of urinary incontinence produced by intrinsic sphincter deficiency.

An In Vitro Method of Studying Functional Responses of Penile Resistance Arteries Under Isobaric Conditions

PURPOSE

We developed an in vitro method that allows us to study the physiopharmacological responses of penile resistance arteries under isobaric conditions.

MATERIALS AND METHODS

Second to third order penile resistance arteries (internal diameter 170 to 210 microm) were mounted in a pressure myograph and cannulated at each end with small glass cannulas (tip external diameter 150 to 180 microm). Internal diameter was continuously recorded and monitored under an intraluminal pressure of 60 mm Hg.

RESULTS

Noradrenaline (0.1 to 0.3 microM) induced a decrease in the luminal diameter of the penile arteries, ie vasoconstriction. This effect was reversed by 1 microM acetylcholine, 1 microM prostaglandin E1 (PGE1) and 1 nM to 1 microM sildenafil citrate. Furthermore, the vasodilatation induced by sildenafil was compared by artery internal diameter values under isometric and isobaric conditions. Although the mean potency of this drug +/- SEM, expressed in pD2, was higher in 5 isometric (7.60 +/- 0.04) than in 4 isobaric (7.03 +/- 0.20) preparations (p <0.05), the slope of the curve was lower in 4 isobaric (0.49 +/- 0.02) than in 5 isometric (1.34 +/- 0.11) studies (p <0.01).

CONCLUSIONS

Under isobaric conditions all vasoactive agents tested inhibited the noradrenaline induced vasoconstriction. Furthermore, the vasodilatory effect of PGE1 beyond baseline diameter could suggest an inhibitory effect of PGE1 on spontaneous myogenic tone. On the other hand, the effect of sildenafil was more potent under isometric than under isobaric conditions. However, the lower slope of the curve under isobaric conditions suggests that the pressure myograph could be a more suitable in vitro model for the study of the activity of penile resistance arteries, and so isobaric conditions correspond more closely to the in vivo situation.

Immunohistochemical and functional evidence for a noradrenergic regulation in the horse penile deep dorsal vein

Our aim was to study the presence of noradrenergic nerves and to characterize the alpha-adrenergic receptors involved in the contractions to electrical field stimulation and to alpha-adrenergic agonists of the horse penile deep dorsal vein. Noradrenergic fibres were visualized by immunohistochemistry using an antibody against dopamine-beta-hydroxylase (DBH). For functional studies, the responses of the venous rings to electrical field stimulation and to alpha-adrenergic agonists (noradrenaline, phenylephrine and BHT 920) were studied in the absence and the presence of noradrenergic transmission- and neuronal sodium channel-blockers (guanethidine and tetrodotoxin, respectively) and of alpha1- and alpha2-adrenergic antagonists (prazosin and rauwolscine, respectively). DBH-immunoreactive fibres were present in the adventitia and in the media layer of the venous rings. Electrical field stimulation (0.5-32 Hz) caused frequency-dependent contractions that were abolished by guanethidine (10(-6) M) and tetrodotoxin (10(-6) M) and reduced by prazosin (10(-9)-10(-7) M) and rauwolscine (3 x 10(-8)-3 x 10(-7) M). Noradrenaline, phenylephrine and BHT 920 induced equipotent contractions of the rings. Prazosin and rauwolscine competitively antagonized the contractions to phenylephrine and BHT 920, respectively. In conclusion, DBH-immunoreactive nerve fibres are present in the horse penile dorsal vein. Both transmural nerve stimulation and alpha-adrenergic agonists induce contraction of the venous rings through a heterogeneous population of alpha1- and alpha2-adrenoceptors.

Contractile response of horse deep dorsal penile vein to histamine

The present investigation was designed to evaluate the effect of histamine on isolated rings of horse deep dorsal penile vein. Under precontracted or basal conditions, histamine evoked an endothelium-independent contraction. Preincubation of the vein rings with the selective H1 receptor antagonist, mepyramine, shifted the concentration-response curve for histamine and to the H1 receptor agonist 2-pyridylethylamine to the right in a competitive manner. Pretreatment with cimetidine, a specific H2 receptor antagonist, did not modify the pEC50 and maximal contraction of the histamine response. Cimetidine and propranolol failed to induce a change in the relaxation caused by dimaprit, the H2 receptor agonist. Histamine contraction was unaffected by thioperamide, the specific H3 receptor antagonist. (R)-alpha-methylhistamine, the H3 receptor agonist, also induced contractions which persisted in the presence of either thioperamide or tetrodotoxin. These data indicate that horse deep dorsal penile vein shows an endothelium-independent contraction response to histamine, mainly mediated by H1 receptors.

Evidence of histamine receptor function in isolated horse penile dorsal arteries

The effect of histamine (10(-9)-10(-3) M) on horse penile dorsal artery was evaluated. Precontracted vessels showed a biphasic response (relaxation-contraction) to histamine, while at basal tone, histamine only induced a contractile effect. The H1 receptor agonist, 2-pyridylethylamine (PEA) (10(-9)-10(-3) M), induced concentration-dependent relaxation in precontracted rings and provoked vasoconstriction at basal tone. Mepyramine (10(-9)-10(8) M), an H1 receptor antagonist, competitively antagonized the relaxant response to histamine (pA2 = 9.7) and PEA (pA2 = 9.2). At basal tone, mepyramine (10(-10)-10(-8) M) also caused a rightward shift in the histamine contraction curve (pA2 = 10.1). Mepyramine (10(-9)-10(-8) M)/PEA Schild plots for resting vessels yielded a pA2 value of 9.4. A regulatory role for H2 and H3 receptors was precluded since there was no response to their agonists (dimaprit (10(-9)-10(-3) M), (R)-alpha-methylhistamine (10(-10)- 3 x 10(-4) M)), and antagonists (cimetidine (10(-5) M), thioperamide (10(-6) M)) did not affect control curves. Removal of the endothelium abolished the relaxant component causing a leftward shift in the contractile component in precontracted rings, with no effect on maximum contraction. Inhibitors of nitric oxide (NO) synthesis, L-NAME (3 x 10(-4) M) and L-NOARG (3 x 10(-4) M), modified the relaxant response while contraction was unaffected. L-Arginine (3 x 10(-4) M) potentiated maximum relaxation but did not affect contraction in precontracted rings. Effects of a prostanoid and K+ channels were ruled out. The biphasic response of precontracted vessels persisted in the presence of indomethacin (3 x 10(-6) M), tetraethylammonium (10(-3) M) and gliblenclamide (10(-5) M). L-NAME plus indomethacin, or this combination plus TEA or glibenclamide produced similar effects as isolated treatments. In resting vessels, histamine contraction was also unaffected by the lack of endothelium, or L-NAME, L-arginine or indomethacin pretreatment. The biphasic response to histamine is probably mediated by H1 receptors with a partial role for NO in the relaxant response in precontracted vessels. In the absence of tone, the contractile effect may be mediated by direct action on smooth muscle.

Endothelium-independent relaxation induced by histamine in human dorsal penile artery

1. In vitro preparations of human dorsal penile arteries were used to evaluate the effect of histamine and to characterize the histamine receptors involved in the response. 2. Cumulative administration of histamine induced a concentration-dependent relaxation in precontracted arteries. The H1 receptor agonist 2-pyridylethylamine induced a biphasic response: contraction followed by dilation. The H2 receptor agonist dimaprit produced a marked relaxation. Mepyramine, a histamine H1 receptor antagonist, led to a slight but statistically significant change in the pD2 value corresponding to the relaxant phase of the H1 receptor agonist and the histamine curve. The H2 receptor antagonist cimetidine induced a marked shift in the dimaprit concentration-response curve without affecting the maximum response. Incubation with cimetidine led to a considerable loss in the sensitivity of the arteries to histamine and in the maximum relaxation. Combined treatment with histamine H1 and H2 receptor antagonists resulted in an additional displacement compared with the effect of each antagonist alone on the histamine response. The effects observed using a histamine H3 receptor agonist and antagonist suggest that the involvement of this receptor is unlikely. 3. Removal of the endothelium was unable to reverse the histamine response. Pretreatment with NG-nitro-L-arginine methyl ester, L-arginine and indomethacin had no effect on the histamine control curve. 4. In conclusion, the vasodilation of human dorsal penile artery induced by histamine seems to be mainly mediated by muscular histamine H2 receptors, without the intervention of key intracellular mediators, such nitric oxide or relaxant prostanoids. A minor population of relaxant histamine H1 receptors cannot be excluded.

Spanish family with Machado-Joseph disease: neurophysiological features and neuropathy study

OBJECTIVES

We have carried out electrophysiological studies and sural nerve biopsy evaluation in a Spanish family with genetically proven Machado-Joseph disease (SCA3/MJD) phenotype III.

PATIENTS AND METHODS

Two symptomatic and other two asymptomatic members of the family were clinically examined. Electrophysiological evaluation included multimodal evoked potentials, quantitative electromyography and nerve conduction studies, and central motor conduction time. We also report neuropathological findings in the sural nerve biopsy in the proband.

RESULTS

Analysis of the SCA3/MJD CAG trinucleotide repeat at the ataxin 3 gene in the DNA of the proband and one of his daughters demonstrated an expanded allele of 63 CAG repeat units. Ataxic pursuit was primary disturbed in MJD, followed by gaze evoked nystagmus, hypermetric saccades and glissades. Limitation of vertical and horizontal gaze, impaired sinusoidal vestibulo-ocular reflex and vestibulo-ocular reflex-fixation-suppression, and active and passive optokinetic nistagmus loss appeared at later stages. Evoked potential studies showed multimodal abnormalities. Electrophysiological and sural nerve biopsy findings correspond well to a pattern of both anterior horn and root ganglion cell distal dominant degeneration. Central motor conduction time was normal in our patients up to advanced stages of the disease.

CONCLUSIONS

Electrophysiological and neuropathological studies suggested widespread peripheral and central affection in MJD. Repeated application of electrophysiological techniques may prove useful for monitoring disease progress.

Motor hand recovery after stroke. Prognostic yield of early transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) was performed in 20 patients within the first days after stroke. Motor evoked potentials (MEPs) were bilaterally recorded over thenar eminence muscles, and central motor conduction time (CMCT), amplitude of the MEPs (A%M) and threshold intensity compared between both sides. Six months later the patients were reexamined. Within the first days after stroke the obtention of MEPs at rest or during voluntary muscle activation have a favorable prognostic value. All patients with early response by TMS reached a good motor function in the following months. The follow-up showed that the electrophysiological improvement was closely related to clinical recovery of the hand function. However, even in cases with a good recovery, the CMCT and, mainly, the A%M, may be significantly different related to those in normal hand. TMS may be an early and valuable prognostic indicator of hand function recovery after stroke, and their prognostic yield is higher than clinical evaluation and CT study. TMS is a quantifiable method of motor disability and may have practical application in the management and rehabilitation therapy in stroke patients.

Central motor conduction in hereditary motor and sensory neuropathy and hereditary spastic paraplegia

Conduction of the central motor pathways (CMCT) by magnetic stimulation of the motor cortex (TMS) was performed in 17 patients with hereditary motor sensory neuropathy (HMSN) and 2 siblings with hereditary spastic paraplegia (HSP). CMCT was prolonged in two patients with HMSN I with associated pyramidal features and in two subjects with HMSN II without clinical pyramidal signs. CMCT may be abnormal in HMSN due to central motor pathways involvement or altered spinal excitability with increased synaptic delay. CMCT was normal in the upper limbs in patients with HSP but increased in the legs. Diagnostic yield of TMS increased in less disabled cases with HSP when selective conduction at the spinal level (C7-S1) was calculated. Abnormal spinal conduction in HSP is consistent with degeneration of the crossed corticospinal tracts at the thoracic level found in neuropathologic observations.

Transcranial magnetic stimulation in amyotrophic and primary lateral sclerosis

Conduction of the central motor pathways after transcranial magnetic stimulation (TMS) was investigated in 7 patients with amyotrophic lateral sclerosis (ALS) and 1 case with primary lateral sclerosis (PLS). Threshold intensity, central motor conduction time (CMCT) and amplitude of the motor evoked potentials (MEPs) were evaluated. Threshold was abnormal in 85% of tested limbs, and CMCT prolonged and amplitude of the MEPs attenuated in 28.5% of patients with ALS. Abnormal CMCT was asymmetric and related to clinical score. MEPs were absent in lower limbs in PLS, with prolonged or attenuated amplitude of the MEPs in upper limbs. EMG showed widespread signs of lower motor neuron involvement in ALS, but not in PLS. Cranial MRI showed frontoparietal cortical atrophy, more marked in pre-central gyrus, and SPECT there was lower tracer uptake in the perirolandic area in the PLS patient. EMG examination, TMS, cranial MRI and SPECT can help in the diagnosis of PLS.

Carpal tunnel syndrome in childhood: study of 6 cases

Six children, 4 girls and two boys, aged 5-14 years, with carpal tunnel syndrome (CTS) are reported. Median nerve entrapment had different aetiologies in each case. One patient developed unilateral CTS symptoms after intensive basketball training. He improved upon terminating this sporting activity. In 3 patients bilateral CTS was associated with Schwartz-Jampel syndrome, trigger finger and mucopolysaccharidosis I (MPS IS = Scheie syndrome), respectively. The latter subject, a boy aged 11 years who had severe bilateral muscle thenar weakness and atrophy, made a good recovery after surgery. Two cases with bilateral CTS had autosomal dominant disease. One of them showed familial CTS with thickening of the transverse carpal ligament. The other child (5 years old) presented early bilateral CTS as first manifestation of hereditary neuropathy with liability to pressure palsies (HNPP). His relatives were asymptomatic, but they showed electrophysiological and nerve biopsy changes consistent with HNPP. Nerve conduction studies (NCS) are diagnostic in paediatric CTS. Moreover, NCS is an objective method to evaluate the evolution of the nerve lesions after surgery. NCS must be performed in nerves of the propositus other than the median, as well as in first degree symptomatic and asymptomatic relatives in order to identify possible familial neuropathies.

The muscle inhibitory period by transcranial magnetic stimulation. Study in stroke patients

Motor evoked potentials (MEPs) elicited over hand muscles by transcranial magnetic stimulation (TMS) were studied in healthy individuals and, bilaterally, in patients with cerebral infarction. Conduction time of the central motor pathways (CMCT), threshold intensity, and amplitude of the MEPs were correlated with recovery motor hand function after stroke. Following MEPs by TMS during tonic muscle contraction, there is a transient suppression of muscle action. This inhibitory period (IP) was significantly shorter in the upper paretic limb of stroke patients with spasticity than in normal limb of the patients and healthy individuals. Shortening of the IP duration was correlated to degree of upper limb spasticity (Ashworth scale) and may be due to supraspinal level reduction of the inhibitory function. The IP study contributes to a better quantification of the hand function in stroke patients.

Urinary albumin excretion in patients with systemic lupus erythematosus without renal disease

OBJECTIVES

To investigate the prevalence of microalbuminuria, urinary albumin excretion (UAE) between 20-200 micrograms/min, in systemic lupus erythematosus (SLE) patients without clinical renal disease, and to discover if this could predict the development of renal disease.

METHODS

This study made six monthly measurements of UAE, creatinine clearance, serological and clinical data in 22 ambulatory women patients with SLE, without clinical renal disease, hypertension, diabetes or heart failure. The patients were followed up for a period of 18 months (four measurements). Age and sex matched healthy controls were used as a comparative group. UAE was measured by nephelometry in three timed overnight urine samples at each visit.

RESULTS

There were no significant differences in the creatinine clearance between the control group and the SLE patients. Creatinine clearance did not show significant changes throughout the study period. SLE patients had wide variations in the UAE rate compared with healthy controls. In five patients (5 of 22; 23%), on occasions, there was mild, transient increase in UAE reaching the level of microalbuminuria. During follow up, one patient with basal (4.67 micrograms/min) and six month (4.73 micrograms/min) normal UAE rate, was admitted with a nephrotic syndrome confirmed on biopsy examination to be proliferative lupus nephritis. Six months after beginning treatment with prednisone and cyclophosphamide her UAE rate returned to normal values (4.65 micrograms/min).

CONCLUSION

SLE patients without clinical renal disease may have microalbuminuria, although this does not seem to warrant any specific action.

Histamine receptors in isolated bovine oviductal arteries

The present in vitro study was designed to evaluate the effect of histamine on isolated rings of bovine oviductal artery and to characterize the histamine receptors involved in the histamine-induced response. Endothelial dependence of the response was also investigated. Cumulative addition of histamine and 2-pyridylethylamine (histamine H receptor agonist) induced a concentration-dependent relaxation in intact arterial segments precontracted with noradrenaline. The histamine H1 receptor antagonist mepyramine showed non-competitive antagonism in the histamine-induced concentration-response curve. However, when the response to histamine was evaluated in the presence of mepyramine and histamine H1 and H3 receptors were blocked, Schild analysis yielded a line with a slope of 1.10 and a pA2 value of 8.91, indicating simple competitive antagonism of mepyramine at histamine H1 receptor sites. The histamine H2 receptor agonist, dimaprit, caused marked dilatation only at high doses. Cimetidine, propranolol and mepyramine failed to inhibit this relaxant effect. In precontracted oviductal arteries, cimetidine did not modify the histamine-induced concentration-response curves. Combined treatment with histamine H1 and H2 receptor antagonists did not induce an additional displacement with respect to the isolated effect of mepyramine thus excluding activation of histamine H2 receptors. Histamine and (R)-alpha-methylhistamine, a selective histamine H3 receptor agonist, produced a moderate contractile effect on the resting tone of preparations. Pretreatment with the selective histamine H1 receptor antagonist decreased the (R)-alpha-methylhistamine response but increased the maximal relaxant effect and abolished the contractile effect of histamine, suggesting the presence of a limited population of contractile histamine H3 receptors. Removal of the endothelium or pretreatment with methylene blue produced a significant inhibition of the relaxant response to histamine. Remaining dilatation was practically abolished by mepyramine and also by indomethacin. The L-arginine analogue, N(omega)-nitro-L-arginine methyl ester (L-NAME) inhibited the effect of histamine and basal production of nitric oxide. L-Arginine, which on its own induced significant endothelium-dependent vasodilatation, reversed the effect of L-NAME on histamine relaxation. Indomethacin only caused a slight modification of the sensitivity of the vessels to histamine, suggesting that prostacyclin or other cyclo-oxygenase products did not make a significant contribution to the model. The absence of the endothelium did not modify the contractile effect of histamine. The results suggest that the relaxant response of isolated oviductal arteries to histamine is dependent on the functional integrity of the endothelium and is mainly mediated by histamine H1 receptors. These receptors may mask a minority presence of histamine H3 contractile receptors located on smooth muscle. The main relaxing factor released from the endothelium by mediation of histamine is nitric oxide, which may also exert an effect on vascular tone.

Conduction velocity along muscle fibers in situ in myasthenia gravis

The muscle fiber conduction velocity (MFCV) was tested distally in the short head of the biceps brachii muscle in 4 patients with ocular and 16 cases with generalized Myasthenia Gravis. The mean MFCV was decreased in 6 cases with generalized form of the disease, 2 of them with short evolution of the symptoms and without drugs therapy. The overall MFCV of 644 fibers in generalized MG was significantly decreased (p < 0.02) related to the results of controls. The MFCV is an index of the muscle fiber size. Muscle fiber atrophy in MG may be due to functional denervation in patients without drugs therapy or to motor neuropathy caused by drugs or associated with thymoma.

Somatosensory evoked potentials and central motor pathways conduction after magnetic stimulation of the brain in diabetes

Somatosensory evoked potentials (SEPs) on stimulating median and posterior tibial nerves, and central and spinal conduction time of the motor pathways calculated by means of magnetic stimulation of the cortex were valuated in diabetic patients. The latencies L1-Cortex and L1-C7 were significantly larger in 54 diabetics than in controls. An increment in L1-C7 interval was found in 17 patients, and the latency L1-Cortex was increased in 20. No patients showed increase in C7-Cortex interval. The increased latency L1-C7 reflects a delayed conduction along afferent spinal pathways in some patients with diabetes in contrast with the normal C7-Cortex supraspinal segment. The central and spinal conduction time after magnetic stimulation of the cortex were normal in 14 out of 15 tested diabetics suggesting that central motor pathways were spared. These results are consistent with the existence of a central-peripheral sensory axonopathy in some diabetics.

Transcranial magnetic stimulation in multiple system and late onset cerebellar atrophies

Central motor conduction time (CMCT) after transcranial magnetic stimulation (TMS) of the cortex, electromyography and nerve conduction velocity were performed in 24 patients with multiple system (MSA) and late onset cerebellar atrophy (LOCA) (often olivopontocerebellar atrophy--OPCA -). CMCT was abnormal in 7 patients with OPCA and one with LOCA. CMCT abnormalities (43% of cases) and increased threshold (68%) were more often found within OPCA group than in another multisystem atrophy and LOCA. Reduction in amplitude of the response after TMS was significantly correlated with cerebral hemispheres's atrophy. Increased threshold was correlated with upper vermal hemisphere atrophy and enlargement of the fourth ventricle. Electrophysiologic signs of mixed peripheral neuropathy were found in 8 patients. TMS abnormalities were not related to peripheral nerve involvement. Marked variation in CMCT suggests heterogeneity in these diseases. However, the percentage of CMCT abnormalities in OPCA group suggests that TMS seems to play a role in the neurophysiological diagnosis of these heterogeneous disorders.

[Clinical and investigative approaches in mitochondrial diseases. A review of 15 cases]

The results of laboratory investigations in concerning 15 patients suspected of mitochondrial disease (MD) are presented. Our purpose is to provide an outline of the investigative modalities that support the clinical suspicion and have been found to be useful in the diagnosis. Five clinical groups were studied including 5 exercise intolerances (2 with inflammatory myopathy), 3 with myopathies (1 with dilated cardiomyopathy), 2 with progressive external oftalmoplegia (1 associated with cerebellar ataxia+epilepsy+hypertrophic cardiomyopathy+pes cavus), 4 with encephalopathies (3 with myoclonic encephalopathies with ataxia and dementia and 1 with epilepsy and tremor), and 1 with metabolic acidosis and cardiomyopathy. We used the following categories of investigative procedures: clinical phenotype analysis including pedigree study, neurophysiological tests, bicycle ergometric evaluation, neuroimaging, microscopic study of skeletal muscle biopsy, post-mortem examination, biochemical assays and molecular genetic studies. EMG showed myopathic changes in 5 cases, features of neuropathy in 2, mixed myopathic and neuropathic pattern in 1 and nonspecific changes in 3. EMG was normal in 3 patients. The most common skeletal muscle abnormalities were variation in fiber size (60%), lipid inclusions (33.3%), oxidative subsarcolemmal aggregates (26.7%) and ragged-red fibers (26.7%). Electron microscopy revealed mitochondrial abnormalities in 8 out of 14 patients' muscle biopsies, and in myocardiac and hepatic tissues of another. Site of biochemical defect was located in 12 patients. Complex I defect in 6, complexes I+IV deficiencies in 3, complex II defect in 1, complex IV deficiency in 1, complexes II+IV deficiencies in 1, and complex III defect in 1. In 2 patients the biochemical defect was not located. Mitochondrial DNA alterations were not found in 7 investigated patients. The clinical spectrum of MD has become increasingly wider. After the clinica suspicion, the diagnosis depends up on the appropriate use of skeletal muscle biopsy, biochemical investigations and molecular genetic techniques. Conventional EMG and automatic measurement of the electromyogram are particularly helpful in confirming the clinical suspicion in patients with predominantly central nervous system disease or in cases in which clinical signs are few.

Motor unit remodelling in Duchenne muscular dystrophy. Electrophysiological assessment

Conventional EMG, motor and sensory conduction velocities, averaging analysis of MUPs, SFEMG, and muscle fiber conduction velocity in situ were performed in 14 boys with Duchenne muscular dystrophy (DD) aged 5 to 11 years. MUPs parameters study showed a striking increment of long duration MUPs followed by satellites and increase of polyphasic potentials of variable duration. The main findings in SFEMG examination were increment in fiber density of the motor unit, large MISI and presence of complex potentials of long duration in all patients. Muscle fiber conduction velocity in situ was significantly slower than in controls, with significant decrease in minimum conduction and increased variability (large SD) in propagation velocity values. Low conduction velocity of muscle fibers, long duration of polyphasics and MUPs followed by satellites, and large MISI were significantly related. These findings support the hypotheses which have suggested that the motor unit remodelling in DD is mainly myogenic. The abnormalities in muscle fiber conduction velocity in situ reflect an increased diameter variation of muscle fibers consistent with splitting fibers, small groups of regenerating and necrotic fibers, and fiber diameter variation found in histological studies. Thus, increased variability in fiber diameter may be the cause of complex and long duration MUPs in DD.

Peripheral nerve conduction and central motor conduction after magnetic stimulation of the brain in myotonic dystrophy

Central motor conduction time was calculated after magnetic stimulation of the brain in 15 patients with myotonic dystrophy and in 38 healthy voluntaries of the same age. Conventional electromyography and motor and sensory conduction velocities were also performed. Central motor conduction time from vertex to C8 was within the normal range in all patients whereas motor conduction velocity of the peripheral nerve and amplitude of the nerve evoked potentials were slightly reduced in 3 and 2 cases respectively, supporting peripheral nerve involvement in some subjects. Our results suggest that the reported central nervous system involvement in myotonic dystrophy, including the nonspecific white matter lesions showed by magnetic resonance imaging, would not affect the conduction of the corticospinal tracts. Magnetic stimulation on the motor cortex is a painless method to study the central nervous system and apports a satisfactory approximation to central motor pathways conduction.

Central motor conduction to upper and lower limbs after magnetic stimulation of the brain and peripheral nerve abnormalities in 20 patients with Friedreich's ataxia

Central motor conduction time (CMCT) to thenar and soleus muscles was measured after magnetic stimulation of the cortex in 20 cases of Friedreich's ataxia (FA) and was abnormal in all. CMCT values were related to disease duration and disability. The amplitude of CMAP after cortex stimulation was severely reduced in the most disabled patients. Reduction in amplitude of the nerve evoked potentials was related neither to disease duration nor grade of disability. These results suggest that clinical worsening in FA is mainly due to progressive central motor pathway involvement. CMCT study is a better index of disease progression than peripheral nerve examination. Abnormalities in CMCT may be the third electrophysiological diagnostic criterion in FA, after reduced amplitude of nerve action potentials and absent H reflex.

Electrophysiologic study in peripheral neuropathy associated with HIV infection

Clinical and electrophysiologic features in 22 patients with HIV infection are reported. Four cases had chronic demyelinating polyneuropathy, two mononeuropathy multiplex, and nine symmetrical sensory-motor polyneuropathy. Seven cases had normal clinical and electromyographic examination. Electrophysiological study had a higher diagnostic yield (68%) than clinical examination (50%) for peripheral neuropathy diagnosis. Thus, peripheral nerve abnormalities are frequent in patients with different stages of HIV infection, although their pathogenesis remains unclear. Symmetrical sensory-motor polyneuropathy is the main type of neuropathy seen in ouvert AIDS, whereas chronic demyelinating polyneuropathy was mainly diagnosed in patients with asymptomatic HIV infection as first manifestation of the disease. Axonal or demyelinating nerve damage was established according to electrophysiological criteria. Frequently a mixture of both lesions was found. Electrophysiologic study is also a good index of neuropathy evolution in HIV infection and to follow-up of nerve abnormalities after treatment.

Central motor pathways conduction after magnetic stimulation of the brain in Cockayne's syndrome

Central motor pathways conduction abnormalities after magnetic stimulation of the brain are reported in two siblings with Cockayne's syndrome. Reduced amplitude of the responses with large central conduction time were the main changes. These results are consistent with signs of diffuse white matter hypomyelination found on MRI. Conversely, only mild changes in conduction velocity of the peripheral nerves were found. Central nervous system involvement can be more severe than peripheral neuropathy in Cockayne's syndrome.

[Trichinosis. A study of a large outbreak on the Iberian peninsula]

An epidemic outbreak of trichinosis after wild boar meat ingestion was analysed. The most frequent clinical manifestations were: muscular pain, fever, periorbitary edema and conjunctivitis. Laboratory tests showed eosinophilia and increased muscular enzymes. There was no mortality. 10 patients had electromyograms, which all showed an inflammatory myopathy pattern. The one fiber study showed similar signs as those found in cases of polymyositis. There was a significant statistical relationship between intensity and duration of symptoms in the intestinal phase and eosinophils levels in peripheral blood. There was also a statistically significant relationship between CPK levels and decrease of mean duration of motor unit potential. Treatment with thiabendazole and steroids was useful. The indirect immunofluorescence test (IIT) proved an excellent method for diagnosing trichinosis.

[Recurrent amyotrophic neuralgia with an unusual clinical expression. Clinical and electrophysiological study]

Neuralgic amyotrophy (NA) is an entity with great variability in its neurological expression. The patient reported here developed symptoms of NA one year before admission, with anterior interosseous nerve palsy. At the time of examination she reports pain in the left upper limb followed by sensory loss over lateral antebrachial cutaneous nerve. Electrophysiologic examination showed signs of chronic denervation in the right anterior interosseous nerve muscles, and reduced amplitude of the sensory nerve action potential of the left lateral antebrachial cutaneous nerve. This case confirms the variety of the nerve involvement in NA, and suggests axonal focal lesions of nerve fascicles or individual peripheral nerve affectation.

[Evaluation of respiratory muscle function (maximal respiratory pressures) in myasthenia gravis]

In myasthenia gravis (MG) the status of respiratory function has a paramount importance and a careful evaluation is recommended. The weakness of respiratory muscles has been demonstrated in several studies. However, a reliable simple method for the evaluation of this muscular group was lacking until recently, when the usefulness of the maximum respiratory pressures, expiratory (MEP) and inspiratory (MIP), was demonstrated. We evaluated with this method a series of 23 patients with a diagnosis of MG (16 females and 7 males), with a mean age of 46 years (22-68 years), clinically stable and without symptomatic dyspnea. They were distributed in: grade I (5), grade II A (12), and grade II B (6). All of them were evaluated with flow-volume curves, pletysmography, gas transfer, MEP and MIP. The resulting values were then correlated with the expected ones, a reduction greater than one SD being considered as abnormal. The results showed that respiratory function was normal without a restrictive pattern. However, the force of respiratory muscles was reduced in the following proportions of patients in the different groups: grade I: MIP 40%, MEP 60%; in grades II A and II B both MEP and MIP were reduced in 84% of patients. When a statistical comparison with the expected values was carried out it was found that MEP and MIP, considered as a group, were reduced to 53% of the expected values (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic inflammatory demyelinating polyneuropathy as first manifestation of human immunodeficiency virus infection

We studied three patients who were admitted to the hospital because of progressive weakness without other systemic signs or symptoms. All three cases were young males who had been intravenous drug user for many years. Electrophysiologic study showed prolonged distal latencies and marked slowing of motor and sensory conduction velocities, consistent with primary demyelination. Nerve biopsy also showed signs of demyelination. Antibodies against HIV in CSF and blood were detected during the diagnostic evaluation. Clinical and electrophysiological studies improved in two cases after prednisone administration. Patients with predominant motor demyelinating neuropathies and risk factors should be screen for HIV infection.

[Multifocal polyneuropathy with persistent conduction blockage. A new subset of chronic inflammatory polyneuropathies]

Recently a subset of chronic demyelinating inflammatory polyneuropathies with asymmetrical involvement limited to upper limbs, at least at the onset, resembling a multifocal mononeuropathy has been described. Electrodiagnostic testing disclosed multifocal CB outside the common entrapment sites has been described. We report a 55 years old man with a 4 years history of paresis, numbness, fasciculations, myokymia, cramps and mild amyotrophy. Electrophysiological evaluation showed proximal multifocal conduction block and abundant spontaneous activity as fasciculations, myokymia and scarce denervation activity. The importance of taking into account this entity in the differential diagnosis of patients with suspected mononeuritis multiplex or motoneuron disease is emphasized. The nosologic place of this entity is also discussed.

Conduction velocity in human muscle fibers in situ. Study in upper and lower limbs in healthy adults

The muscle fibers of the human biceps brachii and vastus medialis muscles were stimulated with low voltages in their distal portion by means of monopolar needles in 50 healthy adults. The electrical activity was recorded proximally by means of a SFEMG electrode. The conduction velocity of the muscle fibers in situ calculated with this method had a Gaussian distribution for both muscles, showed values slightly higher in males than in females, did not decrease significantly with ageing, and was significantly related to limbs perimeter. The recorded potentials and their propagation velocity were the same before than after curarization. The possible interest of the method for testing the muscle fiber function and size in pathological conditions of the nerve and muscle is suggested.

Single fibre and quantitative EMG study in acute stage of human trichinosis

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[Recurrent Miller-Fisher syndrome associated with brachial neuritis]

The clinical and electrophysiological evolution of a 24-year-old patient with Miller-Fisher's syndrome and findings of mild peripheral neuropathy in the electromyographic study is reported. The patient had been treated six years previously for a similar disease and he recovered in 2 months. During the plasmapheresis therapy of the second episode he developed pain and weakness of the left shoulder girdle, and the EMG was consistent with bilateral brachial neuritis. The disease had improved clinically after 6 weeks, except for supracapsular brachial neuropathy; this territory remained denervated after 3 months of evolution. A diagnosis of Crohn's disease had been made between both episodes. The discussion focuses on the rarity of recurrent forms of Miller-Fisher's syndrome and the association of the reported case with brachial neuritis and Crohn's disease.

Electrophysiologic follow-up in Whipple's disease

Neurologic and electrophysiologic findings in a 57-year-old man with Whipple's disease are reported. The patient had severe proximal weakness and weight loss of more than 20 kg. Conventional electromyography and nerve conduction studies suggested mild neuropathy in distal segments of lower limbs and myopathy in proximal muscles. Automatic analysis of the electromyogram in proximal muscles was consistent with myopathy. Conduction velocity of muscle fibers in situ showed low propagation velocity of the impulse. Weakness, weight loss, and all the electrophysiologic parameters improved after treatment, including a compression of the peroneal nerve at the knee, perhaps related to weight loss (slimmer's paralysis).

Slimmer's paralysis: electrophysiological evidence of compressive lesion

A 14-year-old girl developed right peroneal nerve palsy following diet for weight reduction. Peroneal neuropathy started after sitting and leg-crossing. The main electrophysiologic findings showed a severe slowing of conduction velocity in the above-to-below capitulum fibulae segment and a striking reduction in the size of the compound motor action potential when the nerve was stimulated above the knee. These features are consistent with focal demyelination and conduction block of the nerve fibres. The left peroneal nerve showed the same results but less severe. There were no electrophysiological signs of subclinical polyneuropathy. Examination after 3 months was normal. The clinical and electrophysiological features in this case support the compressive origin of the peroneal neuropathy in slimmer's paralysis.

Electrophysiologic study in benign human botulism type B

Conventional electromyography (EMG) and single fiber EMG (SFEMG) were performed in a 64-year-old diabetic woman with mild type B botulism. The main clinical signs were autonomic dysfunction and cranial nerves paresis. Conventional EMG was normal, except for small changes that were consistent with mild mixed peripheral neuropathy in the lower limbs and were related to diabetes. Repetitive stimulation and results of single stimulus before and after full effort were normal. SFEMG showed increased jitter and impulse blocking in clinically normal muscles. The jitter was frequency dependent and improved at a higher innervation rate. Impulse blocking in potentials with only slightly increased jitter was found. The follow-up showed improvement of the jitter in agreement with clinical recovery. Jitter abnormalities were recorded after 16 weeks, when clinical signs of botulism had been reversed to normal. Motor unit fiber density increased progressively, and on examination at 8 weeks, some potentials showed very high jitter values. Both findings might suggest new endplate formation, perhaps due to ultraterminal sprouting development.