Movement disorders in patients with peripheral facial palsy.

Acute unilateral facial paralysis is usually a benign neurological condition that resolves in a few weeks. However, it can also be the source of a transient or long-lasting severe motor dysfunction, featuring disorders of automatic and voluntary movement. This review is organized according to the two most easily recognizable phases in the evolution of facial paralysis: (1). Just after presentation of facial palsy, patients may exhibit an increase in their spontaneous blinking rate as well as a sustained low-level contraction of the muscles of the nonparalyzed side, occasionally leading to blepharospasm-like muscle activity. This finding may be due to an increase in the excitability of facial motoneurons and brainstem interneurons mediating trigeminofacial reflexes. (2). If axonal damage has occurred, axonal regeneration beginning at approximately 3 months after the lesion leads inevitably to clinically evident or subclinical hyperactivity of the previously paralyzed hemifacial muscles. The full-blown postparalytic facial syndrome consists of synkinesis, myokymia, and unwanted hemifacial mass contractions accompanying normal facial movements. The syndrome has probably multiple pathophysiological mechanisms, including abnormal axonal branching after aberrant axonal regeneration and enhanced facial motoneuronal excitability. Although the syndrome is relieved with local injections of botulinum toxin, fear of such uncomfortable contractions may lead the patients to avoid certain facial movements, with the implications that this behavior might have on their emotional expressions.     

Biochemical actions of chronic ethanol exposure in the mesolimbic dopamine system

In previous studies, we have demonstrated that chronic administration of morphine or cocaine produces some common biochemical adaptations in the ventral tegmental area (VTA) and nucleus accumbens (NAc), components of the mesolimbic dopamine system implicated in the reinforcing actions of these and other drugs of abuse. Since this neural pathway is also implicated in the reinforcing actions of ethanol, it was of interest to determine whether chronic ethanol exposure results in similar biochemical adaptations. Indeed, as seen for chronic morphine and cocaine treatments, we show here that chronic ethanol treatment increased levels of tyrosine hydroxylase and glial fibrillary acidic protein immunoreactivity, and decreases levels of neurofilament protein immunoreactivity, in the VTA. Also like morphine and cocaine, ethanol increases levels of cyclic AMP-dependent protein kinase activity in the NAc. These actions of ethanol required long-term exposure to the drug, and were in most cases not seen in the substantia nigra or caudate-putamen, components of the nigrostriatal dopamine system studied for comparison. Altered levels of tyrosine hydroxylase in catecholaminergic cells frequently reflect altered states of activation of the cells. Moreover, increasing evidence indicates that ethanol produces many of its acute effects on the brain by regulating NMDA glutamate and GAB_A receptors. We therefore examined the influence of chronic ethanol treatment on levels of expression of specific glutamate and GABA receptor subunits in the VTA. It was found that long-term, but not short-term, ethanol exposure increased levels of immunoreactivity of the NMDARl subunit, an obligatory component of NMDA glutamate receptors, and of the Glu Rl subunit, a component of many AMPA glutamate receptors; but at the same time, long-term ethanol exposure decreased immunoreactivity levels of the α1 subunit of the GABA_A receptor complex. These changes are consistent with an increased state of activation of VTA neurons inferred from the observed increase intyrosine hydroxylase (TH) expression. These results demonstrate that chronic ethanol exposure results in several biochemical adaptations in the mesolimbic dopamine system, which may underlie prominent changes in the structural and functional properties of this neural pathway related to alcohol abuse and alcoholism. © 1995 Wiley-Liss, Inc.     

Niflumic acid-induced increase in potassium currents in frog motor nerve terminals: effects on transmitter release

The actions of the nonsteroidal antiinflammatory drug niflumic acid were studied on frog neuromuscular preparations by conventional electrophysiological techniques. Niflumic acid reduced the amplitude and increased the latency of endplate potentials in a concentration-dependent manner. Neuromuscular junctions pretreated with niflumic acid (0.05–0.5 mM) showed much less depression than control when they were stimulated with trains of impulses. Inhibition of acetylcholine release was reverted by raising the extracellular Ca²⁺ concentration but not by simply washing out the preparations with niflumic acid-free solutions. Pretreatment with indomethacin (0.1 mM), another nonsteroidal antiinflamatory drug, did not affect the niflumic acid-induced inhibition of evoked responses. Niflumic acid (0.1 mM) did not change the amplitude of miniature endplate potentials and had a dual action on the frequency of miniatures: it decreased their frequency at 0.1 mM whereas it produced an enormous increase in the rate of spontaneous discharge at 0.5 mM. Niflumic acid (0.1–1 mM) reversibly increased the amplitude and affected the kinetics of presynaptic voltage-activated K⁺ current and Ca²⁺-activated K⁺ current in a concentration-dependent manner. Niflumic acid (0.1–1 mM) irreversibly decreased the amplitude and reversibly affected the kinetics of the nodal Na⁺ current. Indomethacin (0.1 mM) had no effect on presynaptic currents. In conclusion, niflumic acid reduces acetylcholine release by increasing presynaptic K⁺ currents. This may shorten the depolarizing phase of the presynaptic action potential and may reduce the entry of Ca²⁺ with each impulse.     

The role of Serratia marcescens porins in antibiotic resistance

The outer membrane permeability of Serratia marcescens was studied by comparing porin-deficient mutants with their parental strains. Omp1-deficient strains were selected by moxalactam resistance, whereas mutants lacking the Omp2 porin were obtained by experimental infection with the SMP2 phage, whose primary receptor is the Omp2 porin. The role of porins was demonstrated in quinolone accumulation assays, where semiquantitative differences in accumulation were observed. Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain. The clinical isolates S. marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent.     

Differences in virulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men

Differences in the presence of nine urovirulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men have been studied. Hemolysin and necrotizing factor type 1 occur significantly more frequently among isolates causing prostatitis than among those causing cystitis (P < 0.0001) or pyelonephritis (P < 0.005). Moreover, the papGIII gene occurred more frequently in E. coli isolates associated with prostatitis (27%) than in those associated with pyelonephritis (9%) (P < 0.05). Genes encoding aerobactin and PapC occurred significantly less frequently in isolates causing cystitis than in those causing prostatitis (P < 0.01 and P < 0.0001, respectively) and pyelonephritis (P < 0.01 and P < 0.0001, respectively). No differences in the presence of Sat or type 1 fimbriae were found. Finally, AAFII and Bfp fimbriae are no longer considered uropathogenic virulence factors since they were not found in any of the strains analyzed. Overall, the results showed that clinical isolates producing prostatitis need greater virulence than isolates producing pyelonephritis in women or, in particular, cystitis in women (P < 0.05). Overall, the results suggest that clinical isolates producing prostatitis are more virulent that those producing pyelonephritis or cystitis in women.     

New evidence from magnetic resonance imaging of brain changes after climbs at extreme altitude

The aim of the present study was to look for anatomical changes in climbers' brains, using magnetic resonance imaging (MRI), after extremely high-altitude climbs and to relate them to possible associated risk factors. Clinical history, neurological examinations and MRI were carried out on a group of nine climbers before and after climbing to over 7500 m without the use of supplementary oxygen. None of the subjects showed any neurological dysfunctions. In five climbers MRI abnormalities (high signal areas, cortical atrophy) were observed before the expedition. After the descent, two of them showed new high intensity signal areas recorded by MRI. Both subjects suffered severe neurological symptoms during the climb. The present study suggested that the brain changes observed by MRI could be related to the severity of clinical events at high altitude. However, we do not know the exact meaning of such MRI findings or the reason for their location, predominantly in posterior regions of the brain. The new evidence that a high percentage of climbers show MRI brain abnormalities, and especially the appearance of changes after the ascent, reinforces the possibility of a potential neurological risk in high-altitude climbing.     

Effect of using the flow or the volume signals on the measurement of nonapneic respiratory events

STUDY OBJECTIVES: To assess whether the measurement of breathing reduction during obstructive sleep events depends on using the flow or the volume signals recorded with a pneumotachograph. DESIGN: Prospective observational study. SETTING: Sleep laboratory in a University Hospital. PATIENTS OR PARTICIPANTS: Data from 10 male patients with sleep apnea (54 +/- 11 years, apnea-hypopnea index: 43 +/- 21 events/hour, body mass index: 30 +/- 2 kg/m2). INTERVENTIONS: Slow modification of continuous positive airway pressure was performed during full-polysomnography continuous positive airway pressure titration. MEASUREMENTS AND RESULTS: Air flow was measured by a pneumotachograph, and volume was computed by numerical integration. Obstructive events of different magnitude were selected. In 500 breathing cycles analyzed, the reduction in tidal volume was greater than the reduction in the flow amplitude: mean difference of 0.091 (i.e., 9.1% amplitude) and limits of agreement of 0.095 and -0.277 (i.e., 9.5% and -27.7% amplitude). In 14% of the cycles, the reduction in flow was < 50%, whereas the reduction in volume was > 50%, resulting in discordant event classification. CONCLUSIONS: The quantification of breathing reduction depends on whether the flow or the volume signal is used to assess breathing during sleep.     

Velocity recovery cycles of C fibres innervating human skin

The purpose of this study was to determine whether induced expression of the Ca²⁺ buffering protein parvalbumin (PV) in slow-twitch fibres would lead to alterations in physiological, biochemical and molecular properties reflective of a fast fibre phenotype. Transgenic (TG) mice were generated that overexpressed PV in slow (type I) muscle fibres. In soleus muscle (SOL; 58 % type I fibres) total PV expression was 2- to 6-fold higher in TG compared to wild-type (WT) mice. Maximum twitch and tetanic tensions were similar in WT and TG but force at subtetanic frequencies (30 and 50 Hz) was reduced in TG SOL. Twitch time-to-peak tension and half-relaxation time were significantly decreased in TG SOL (time-to-peak tension: 39.3 ± 2.6 vs. 55.1 ± 4.7 ms; half-relaxation time: 42.1 ± 3.5 vs. 68.1 ± 9.6 ms,   P < 0.05  for TG vs. WT, respectively;   n = 8  –10). There was a significant increase in expression of type IIa myosin heavy chain (MHC) and ryanodine receptor at the mRNA level in TG SOL but there were no differences in MHC expression at the protein level and thus no difference in fibre type. Whole muscle succinate dehydrogenase activity was reduced by 12 ± 0.4 % in TG SOL and single fibre glycerol-3-phosphate dehydrogenase activity was decreased in a subset of type IIa fibres. These differences were associated with a 64 % reduction in calcineurin activity in TG SOL. These data show that overexpression of PV, resulting in decreased calcineurin activity, can alter the functional and metabolic profile of muscle and influence the expression of key marker genes in a predominantly slow-twitch muscle with minimal effects on the expression of muscle contractile proteins.     

Release of ATP induced by hypertonic solutions in Xenopus oocytes

ATP mediates intercellular communication. Mechanical stress and changes in cell volume induce ATP release from various cell types, both secretory and non-secretory. In the present study, we stressed Xenopus oocytes with a hypertonic solution enriched in mannitol (300 m m ). We measured simultaneously ATP release and ionic currents from a single oocyte. A decrease in cell volume, the activation of an inward current and ATP release were coincident. We found two components of ATP release: the first was associated with granule or vesicle exocytosis, because it was inhibited by tetanus neurotoxin, and the second was related to the inward current. A single exponential described the correlation between ATP release and the hypertonic-activated current. Gadolinium ions, which block mechanically activated ionic channels, inhibited the ATP release and the inward current but did not affect the decrease in volume. Oocytes expressing CFTR (cystic fibrosis transmembrane regulator) released ATP under hypertonic shock, but ATP release was significantly inhibited in the first component: that related to granule exocytosis. Since the ATP measured is the balance between ATP release and ATP degradation by ecto-enzymes, we measured the nucleoside triphosphate diphosphohydrolase (NTPDase) activity of the oocyte surface during osmotic stress, as the calcium-dependent hydrolysis of ATP, which was inhibited by more than 50 % in hypertonic conditions. The best-characterized membrane protein showing NTPDase activity is CD39. Oocytes injected with an antisense oligonucleotide complementary to CD39 mRNA released less ATP and showed a lower amplitude in the inward current than those oocytes injected with water.     

Determinants of plasma homocyst(e)ine in patients with nephrotic syndrome

Hyperhomocyst(e)inemia is an independent risk factor for atherothrombosis in several clinical settings in which renal function is impaired, but its prevalence in the nephrotic syndrome has not been investigated in detail, even though this syndrome provides an excellent model in which to study a possible link between albuminuria, proteinuria, and hyperhomocyst(e)inemia. We obtained plasma and urine from 27 patients with biopsy-confirmed membranous glomerulonephritis presenting nephrotic syndrome and 27 matched controls and determined the concentrations of homocyst(e)ine and proteins considered putative markers of glomerular and tubular function. Hyperhomocyst(e)inemia, defined as the mean +SD of the plasma homocyst(e)ine concentration of the controls [plasma homocyst(e)ine concentration >10.8 micromol/l] was present in 26% of the patients with nephrotic syndrome but in only 7.4% of the controls. Furthermore, the degree of hyperhomocyst(e)inemia was more severe in the nephrotic patients than in the controls. The existence of renal failure, tubular damage, and, interestingly, relatively well conserved glomerular function barrier were the main predictors of increased levels of plasma homocyst(e)ine. In conclusion, hyperhomocyst(e)inemia is a frequent cardiovascular risk factor present in patients with nephrotic syndrome and renal failure, but it is not directly associated with proteinuria.