Paradoxical increase in striatal neuropeptide gene expression following ischemic lesions of the cerebral cortex.

Ischemic lesions of the cerebral cortex occur frequently in humans as a result of stroke. One major consequence of the death of cortical neurons is the loss of excitatory cortical projections to subcortical regions. Little is known, however, about the transsynaptic effect of such lesions on neurotransmitter expression in subcortical structures. We have examined the effects of ischemic cortical lesions on the peptidergic neurotransmitters enkephalin and tachykinins in the striatum, a brain region massively innervated by glutamatergic cortical inputs. The levels of enkephalin and tachykinin mRNAs increased in the striatum of adult rats after thermocoagulation of pial vessels. The effects were more pronounced in the striatal region most heavily innervated by the lesioned cortex but were also observed in other striatal regions and on the contralateral side. Increased gene expression was accompanied by increased immunoreactivity for the two peptides. Elevated levels of enkephalin mRNA were observed up to 3 months after surgery in the ipsilateral striatum. Whereas results of previous studies of acute cortical ablations suggested that excitatory corticostriatal neurons were necessary to maintain normal peptide levels in striatal efferent neurons, the present data indicate that lesions of the same corticostriatal neurons secondary to local ischemia result in a paradoxical transsynaptic activation of neuropeptide synthesis in subcortical structures. This effect may play a role in the functional consequences of cortical strokes and progressive cortical atrophy in humans and may have critical bearing for their treatment and prognosis.     

Lesion Study of the Distribution of Serotonin 5-HT4 Receptors in Rat Basal Ganglia and Hippocampus

The regional distribution of 5-hydroxytryptamine (5-HT₄) receptors labelled with [³H]GR113808 was examined in rat basal ganglia and hippocampus after specific lesions. Lesion of serotonin neurons induced by injections of 5,7-dihydroxytryptamine into the dorsal and medial raphe nuclei resulted in increased 5-HT₄ receptor binding in most regions examined, compared with controls. More precisely, there was a 78% increase in the rostral but no change in the caudal part of caudate-putamen, and 83% and 54% increases in the shell and core of the nucleus accumbens respectively. In the substantia nigra, the increase in 5-HT₄ binding was larger (72%) than that in the globus pallidus (32%). In the hippocampus, 63%, 30% and 28% increases were measured in CA2, CA1 and CA3 respectively. Following lesion of dopamine neurons by intranigral injection of 6-hydroxydopamine, increased 5-HT₄ receptor binding was observed in the caudal (59%), but not the rostral part of caudate-putamen, as well as in the globus pallidus (93%). Since no decreases in 5-HT₄ receptor density were detected after the dopamine lesion, it was concluded that these receptors are not expressed in dopamine neurons. Kainic acid lesions of the caudate-putamen were associated with dramatic local decreases in 5-HT₄ receptor binding on the injected side (-89%), which suggested that striatal neurons express 5-HT₄ receptors. Corresponding decreases of 72 and 20% in receptor density were detected in globus pallidus and substantia nigra, consistent with a presumed localization of 5-HT₄ receptors on striatal GABA neurons projecting to these regions. In the substantia nigra, the decrease in [³H]GR113808 binding was localized to the pars lateralis, indicating that striatal neurons belonging to the cortico-striato-nigrotectal pathway, and containing GABA and dynorphin, express 5-HT₄ receptors.     

Response selectivity of neurons in area MT of the macaque monkey during reversible inactivation of area V1.

1. Behavioral results in the monkey and clinical studies in human show remarkable residual visual capacities after a lesion of area V1. Earlier work by Rodman et al. demonstrated that visual activity can be recorded in the middle temporal area (MT) of the macaque monkey several weeks after a complete lesion of V1. These authors also tested the effect of a reversible block of area V1 on the visual responses of a small number of neurons in area MT and showed that most of these cells remain visually responsive. From the results of that study, however, it is difficult to assess the contribution of area 17 to the receptive-field selectivity of area MT neurons. To address this question, we have quantitatively measured the effects of a reversible inactivation of area 17 on the direction selectivity of MT neurons. 2. A circular part of the opercular region of area V1 was reversibly inactivated by cooling with a Peltier device. A microelectrode was positioned in the lower layers of V1 to control the total inactivation of that area. Eighty percent of the sites recorded in the retinotopically corresponding region of MT during inactivation of V1 were found to be visually responsive. The importance of the effect was assessed by calculating the blocking index (0 for no effect, 1 for complete inactivation). Approximately one-half of the quantitatively studied neurons gave a blocking index below 0.6, illustrating the strong residual responses recorded in many neurons. 3. Receptive-field properties were examined with multihistograms. It was found that, during inactivation of V1, the preferred direction changed for most neurons but remained close to the preferred direction or to its opposite in the control situation. During inactivation of V1, the average tuning curve of neurons became broader mostly because of strong reductions in the response to directions close to the preferred and nonpreferred. Very little change was observed in the responses for directions at 90 degrees to the optimal. These results are consistent with a model in which direction selectivity is present without an input from V1 but is reinforced by the spatial organization of this excitatory input. 4. Residual responses were found to be highly dependent on the state of anesthesia because they were completely abolished by the addition of 0.4-0.5% halothane to the ventilation gases. Finally, visual responses were recorded in area MT several hours after an acute lesion of area 17.(ABSTRACT TRUNCATED AT 400 WORDS)     

Single step multiplex real-time RT-PCR for H5N1 influenza A virus detection

H5N1 influenza A virus causes a rapidly fatal systemic disease in domestic poultry and spreads directly from poultry to mammalian species such as leopards, tigers and humans. The aim of this study was to develop a multiplex real-time RT-PCR for rapid detection of H5N1 influenza A virus. The selected primers and various labeled TaqMan MGB reporter probes corresponding to M, H5 and N1 were used in a single step multiplex real-time RT-PCR to simultaneously detect triple fluorescent signals. In order to validate the method, 75 clinical specimens infected with H5N1 isolated from both poultry and mammals, as well as various specimens of other subtypes and RNA from other viral pathogens of poultry and human were tested. The results showed that the multiplex real-time RT-PCR assays can be applied to detect virus suspensions of H5N1 influenza A virus from a wide host range and demonstrated the sensitivity of the assay amounted to approximately 10(2)-10(3)copies/mul. In conclusion, the highlights of this particular method lie in its rapidity, specificity and sensitivity thus rendering it feasible and effective for large-scale screening at times of H5N1 influenza A virus outbreaks.     

Identification of risk factors for voiding dysfunction following TVT placement

OBJECTIVE: To determine preoperative risk factors of postoperative voiding dysfunction after tension-free vaginal tape (TVT) procedure. METHODS: In 2004, 100 patients with genuine stress urinary incontinence underwent surgery by the TVT procedure. Preoperative and postoperative urodynamic study was performed for each patient. Postoperatively, patients' perception of result and quality of life were assessed on two validated scales, namely, Mesure du Handicap Urinaire (MHU) and Ditrovie. Voiding dysfunction was defined by a postoperative peak flow rate of <15 ml/s at 3 mo. Clinical and urodynamic parameters were compared and analysed. RESULTS: At 3 mo, 20 patients (20%) showed evidence of voiding dysfunction despite the absence of clinical symptoms in 14 of them (70%). Multivariate analysis showed that age (p<0.038) and preoperative peak flow rate (p<0.001) were independent risk factors for voiding dysfunction. Parity, menopausal status, body mass index, and maximal urethral closure pressure were not statistically related to the risk of voiding dysfunction. CONCLUSIONS: This study confirms the existence of an important rate of postoperative voiding dysfunction, mostly asymptomatic, and identifies age and preoperative maximal peak flow rate as independent preoperative risk factors. Identification of voiding dysfunction in patients may lead to better follow-up and early detection of late potential complications of suburethral procedures.     

Linezolid in the treatment of brain abscess due to Peptostreptococcus

Brain abscesses can be caused by bacteria, fungi, and parasites. Among bacteria, anaerobic organisms include the Bacteroides species group, Fusobacterium, Peptostreptococcus, and Propionibacterium. In these cases, a 4-week course of parenteral penicillin/cefalosporin and metronidazole is the standard of treatment. We describe a case of brain abscess secondary to anaerobic infection with Peptostreptococcus, which was successfully treated with parenteral and oral linezolid after failure of standard therapy.     

Seasonal and Pandemic Human Influenza Viruses Attach Better to Human Upper Respiratory Tract Epithelium than Avian Influenza Viruses

Influenza viruses vary markedly in their efficiency of human-to-human transmission. This variation has been speculated to be determined in part by the tropism of influenza virus for the human upper respiratory tract. To study this tropism, we determined the pattern of virus attachment by virus histochemistry of three human and three avian influenza viruses in human nasal septum, conchae, nasopharynx, paranasal sinuses, and larynx. We found that the human influenza viruses—two seasonal influenza viruses and pandemic H1N1 virus—attached abundantly to ciliated epithelial cells and goblet cells throughout the upper respiratory tract. In contrast, the avian influenza viruses, including the highly pathogenic H5N1 virus, attached only rarely to epithelial cells or goblet cells. Both human and avian viruses attached occasionally to cells of the submucosal glands. The pattern of virus attachment was similar among the different sites of the human upper respiratory tract for each virus tested. We conclude that influenza viruses that are transmitted efficiently among humans attach abundantly to human upper respiratory tract, whereas inefficiently transmitted influenza viruses attach rarely. These results suggest that the ability of an influenza virus to attach to human upper respiratory tract is a critical factor for efficient transmission in the human population.Influenza is an important cause of morbidity and mortality in humans during seasonal, pandemic, and zoonotic outbreaks. Seasonal influenza is estimated to cause 250,000 to 500,000 deaths per year worldwide. Pandemic influenza viruses of the previous century resulted in an estimated 1 to 4 million deaths for the 1957 H2N2 (Asian flu) and the 1968 H3N2 (Hong Kong flu) influenza pandemics, and 20 to 50 million deaths for the 1918 H1N1 (Spanish flu) influenza pandemic.^1,2 The first influenza pandemic of the 21st century, the currently ongoing new H1N1 virus outbreak (Mexican flu), has caused at least 3486 deaths as of September 13, 2009 (http://www.who.int/csr/don/2009_09_18/en/index.html). The zoonotic highly pathogenic avian influenza virus (HPAIV) H5N1, which is causing an ongoing outbreak in poultry, only occasionally infects humans, but has a high mortality rate, with 262 deaths out of 400+ confirmed infections as of August 2009 (http://www.who.int/csr/disease/avian_influenza/country/cases_table_2009_08_11/en/index.html).The pandemic potential of an influenza virus depends largely on its efficiency of human-to-human transmission. Human influenza viruses, including seasonal H1N1 and H3N2 viruses, and the pandemic H1N1 virus, are transmitted efficiently.³ In contrast, the zoonotic HPAIV H5N1 is only rarely transmitted from human to human.⁴ However, the factors determining efficient virus transmission among humans are poorly understood.Tropism of influenza virus for the human upper respiratory tract (URT) has been speculated to be an important determinant for the efficiency of virus transmission, based both on receptor distribution and virus replication studies.^5,6 Based on lectin histochemistry, the human URT has abundant receptors for human influenza viruses, which are efficiently transmitted.^5,7 This fits with the ability for human influenza viruses to replicate in human URT tissues based on in vivo,⁸ ex vivo,⁷ and in vitro studies.^9,10,11 In contrast, the human URT has only limited receptors for avian influenza viruses.^5,7 This fits with the absence or rarity of HPAIV H5N1 transmission among humans.⁴ However, it is discordant with a study of Nicholls and others, who showed that HPAIV H5N1 can replicate in URT tissues. They explained this discordance by suggesting that HPAIV H5N1 attached to receptors not detected by the lectins used. Therefore, there is currently no consensus on the tropism of HPAIV H5N1 for the human URT. In addition, the studies to date have not studied the human URT systematically, and it is not known what the tropism of the new H1N1 virus is for the human URT.To address the question whether URT tropism of influenza viruses is linked to efficient transmission, we determined the pattern of attachment of selected influenza viruses in the human URT: human influenza viruses, including seasonal H1N1 and H3N2 viruses and pandemic H1N1 virus, which are transmitted efficiently, and avian influenza viruses, including a HPAIV H5N1, isolated from a fatal human case, which is not transmitted efficiently among humans. We measured the pattern of virus attachment by use of virus histochemistry instead of lectin histochemistry.⁶ Virus histochemistry measures the attachment of influenza virus to its host cell directly. Therefore, any receptors other than SA-α-2,3-Gal terminated saccharides and SA-α-2,6-Gal terminated saccharides also would be detected by virus histochemistry. We have used this technique previously to show that the pattern of attachment in the human lower respiratory tract is different for human and avian influenza viruses, which correlates with differences in primary disease.¹²     

Dysfunction of the cortico-basal ganglia-cortical loop in a rat model of early parkinsonism is reversed by metabotropic glutamate receptor 5 antagonism

This study examined the cellular correlates of the akinetic deficits produced in Wistar rats by discrete bilateral 6-hydroxydopamine (6-OHDA) striatal infusions in the dorsolateral striatum, mimicking the preferential denervation of the motor striatal territory in early symptomatic stage of Parkinson's disease (PD). Intraneuronal gene expression of cytochrome oxidase subunit I (COI), a metabolic index of neuronal activity, was increased in the subthalamic nucleus, substantia nigra pars reticulata and decreased in frontal cortical areas, but paradoxically unchanged in the striatum, globus pallidus, entopeduncular nucleus and ventrolateral thalamic nucleus. Neither preproenkephalin A nor preprotachykinin mRNA expression, markers of striatal projection neurons, were modified in the denervated striatal area despite 90% loss of dopamine (DA) terminals. Preproenkephalin A mRNA expression was however, decreased in the nondepleted striatal region, suggesting compensatory increase of dopamine tone from those spared areas. A chronic treatment with the metabotropic glutamate receptor 5 (mGluR5) antagonist 2-methyl-6-(phenylethylnyl)-pyridine (MPEP), which alleviated the akinetic disorders produced by the lesion, reversed the lesion-induced variations of COI gene expression, moderately increased this marker in the structures unaffected by the lesion and did not modify the striatal neuropeptides gene expression. These data suggest that the expression of akinetic deficits in early parkinsonism is associated with focused metabolic changes in the cortico-basal ganglia-cortical loop downstream of the striatum and pallidal complex.     

Single-step multiplex reverse transcription-polymerase chain reaction (RT-PCR) for influenza A virus subtype H5N1 detection

Influenza A virus subtype H5N1 causes a rapidly fatal systemic disease in domestic poultry and spreads directly from poultry to humans. The aim of this study was to develop a rapid, cost-saving and effective method for influenza A virus subtype H5N1 detection. The selected primer set was used in single-step RT-PCR for simultaneous detection in multiplex format of the 276-, 189-, and 131-bp fragments, corresponding to sequences specific for M, H5 and N1. The amplified DNA fragments were clearly separated by agarose gel electrophoresis. The sensitivity of this assay was about 10(3) copies/microL. Moreover, this method can be applied to detect not only avian but also human influenza A virus subtype H5N1. In conclusion, the highlights of this particular method are its rapidity and cost-effectiveness, thus rendering it feasible and attractive for large-scale screening at times of influenza A virus subtype H5N1 outbreak.