Probing the cortical neuronal correlates of a sensory discrimination process

Key to understanding perception is the form of how sensory stimuli are represented in the evoked activity of the brain. Here, we addressed the question of which components of the evoked neuronal activity in the somatosensory cortex represent the stimulus features while trained monkeys discriminated the difference in frequency between two vibrotactile stimuli. We probed whether these cortical neuronal representations are essential to perception. The results show a strong link between the cortical representation of the stimulus and perception.

[Study of the betalactam resistance of Haemophilus influenzae conferred by the bla(ROB-1) gene]

Given the lack of information on the resistance to betalactams conferred by the bla(ROB-1) gene in our area, we decided to undertake a study to determine if and how often it appears in our isolates. We analyzed the presence of the gene in 177 strains of Haemophilus influenzae and compared the results with those from the biochemical tests (nitrocefin). Sixty-three strains tested positive in the nitrocefin test (35.6%). The presence of the bla(ROB-1) gene was detected in seven of the 177 strains (3.9%). All the strains expressing the gene also tested positive in the nitrocefin test. Of the 63 strains that showed biochemical resistance (positive to nitrocefin), seven were found to be caused by the presence of the bla(ROB-1) gene. An epidemiological follow-up for the presence of this gene in our area is therefore advisable.

xln23 from Streptomyces chattanoogensis UAH23 encodes a putative enzyme with separate xylanase and arabinofuranosidase catalytic domains

The xylanase gene xysA of Streptomyces halstedii JM8 was used to isolate a DNA fragment from a gene library of Pstl-digested chromosomal DNA of the lignocellulolytic actinomycete Streptomyces chattanoogensis CECT-3336. Nucleotide sequence analysis revealed a gene (xln23) encoding a bifunctional multimodular enzyme bearing two independent xylanase and alpha-L-arabinofuranosidase domains separated by a Ser/Gly-rich linker. The N terminus of the predicted protein showed high homology to family F xylanases. The C terminus was homologous to amino acid sequences found in enzymes included in the glycosyl hydrolase family 62 and, in particular, to those of alpha-L-arabinofuranosidase AbsB from Streptomyces lividans. PCR and RT-PCR experiments showed that the nucleotide sequences corresponding to each domain are arranged as expected on the chromosomal DNA and that they are cotranscribed. To our knowledge, this is the first description of xylanase and arabinofuranosidase domains in a same open reading frame.

[Neural codes for perception]

OBJECTIVE

This article describes experiments designed to show the neural codes associated with the perception and processing of tactile information.

DEVELOPMENT

The results of these experiments have shown the neural activity correlated with tactile perception. The neurones of the primary somatosensory cortex (S1) represent the physical attributes of tactile perception. We found that these representations correlated with tactile perception. By means of intracortical microstimulation we demonstrated the causal relationship between S1 activity and tactile perception. In the motor areas of the frontal lobe is to be found the connection between sensorial and motor representation whilst decisions are being taken.

CONCLUSIONS

S1 generates neural representations of the somatosensory stimuli which seen to be sufficient for tactile perception. These neural representations are subsequently processed by central areas to S1 and seem useful in perception, memory and decision making.

Influence of hydrolysis, purification, and calibration method on furosine determination using Ion-pair reversed-phase high-performance liquid chromatography

The influence of HCI concentration (6M, 8M, and 10M) and the ratio of sample protein to acid (1 or 5 mg of protein per mL of acid) on furosine formation during sample hydrolysis is studied. The conditions that maximize furosine formation are 10M HCI in the ratio of 1 mg of protein to 1 mL of acid. Purification of the hydrolysate by solid-phase extraction is also considered by examining the effect of hydrolysate volume and volume of 3M HCI used to elute the furosine. Furosine quantitation is carried out using the standard additions and external standard methods. The results indicate that there is no interference by the sample matrix and that external calibration is adequate.

Reduction of Ca(2+) channel activity by hypoxia in human and porcine coronary myocytes

OBJECTIVE

Oxygen (O(2)) tension is a major regulator of blood flow in the coronary circulation. Hypoxia can produce vasodilation through activation of ATP regulated K(+) (K(ATP)) channels in the myocyte membrane, which leads to hyperpolarization and closure of voltage-gated Ca(2+) channels. However, there are other O(2)-sensitive mechanisms intrinsic to the vascular smooth muscle since hypoxia can relax vessels precontracted with high extracellular K(+), a condition that prevents hyperpolarization following opening of K(+) channels. The objective of the present study was to determine whether inhibition of Ca(2+) influx through voltage-dependent channels participates in the response of coronary myocytes to hypoxia.

METHODS

Experiments were performed on porcine anterior descendent coronary arterial rings and on enzymatically dispersed human and porcine myocytes of the same artery. Cytosolic [Ca(2+)] was measured by microfluorimetry and whole-cell currents were recorded with the patch clamp technique.

RESULTS

Hypoxia (O(2) tension approximately 20 mmHg) dilated endothelium-denuded porcine coronary arterial rings precontracted with high K(+) in the presence of glibenclamide (5 microM), a blocker of K(ATP) channels. In dispersed human and porcine myocytes, low O(2) tension decreased basal cytosolic [Ca(2+)] and transmembrane Ca(2+) influx independently of K(+) channel activation. In patch clamped cells, hypoxia reversibly inhibited L-type Ca(2+) channels. RT-PCR indicated that rHT is the predominant mRNA variant of the alpha(1C) Ca(2+) channel subunit in human coronary myocytes.

CONCLUSION

Our study demonstrates, for the first time in a human preparation, that voltage-gated Ca(2+)channels in coronary myocytes are under control of O(2) tension.

Osteoblasts in HIV-infected patients: HIV-1 infection and cell function

BACKGROUND

HIV-infected patients have been shown to have a severe alteration in osteoblast function that appears to be related to the infection.

OBJECTIVE

To determine whether normal human osteoblasts express CD4, whether osteoblasts from patients with HIV infection are infected by HIV-1 and whether osteoblast dysfunction observed in vivo also occurs in vitro.

METHODS

Osteoblast cultures from bone marrow biopsies of HIV-infected patients (n = 14) and control patients (n = 10) were used in a cross-sectional study and a case-control prospective study. Expression of CD4 was analysed using flow cytometry and reverse transcriptase polymerase chain reaction; the presence of HIV-1 particles was determined by measuring p24 antigen in the supernatants of osteoblast cultures and viral DNA or RNA in the osteoblasts using the polymerase chain reaction. Osteoblast function was assessed by measuring cell proliferation, type I collagen and osteocalcin synthesis.

RESULTS

In human osteoblasts, CD4 expression could not be determined using flow cytometry, although low levels of mRNA coding for CD4 were detected. HIV infection was not observed in osteoblast cultures from HIV-infected patients nor was there any alteration in replication and synthesis of type I collagen, although osteocalcin synthesis was increased.

CONCLUSIONS

It is unlikely that HIV-1 infects human osteoblasts in vivo; therefore, the hypothesis that these cells could act as local HIV-1 reservoirs should be reconsidered.

Assessment of cerebral perfusion and cerebrovascular reserve in insulin-dependent diabetic patients without central neurological symptoms by means of 99mTc-HMPAO SPET with acetazolamide

The detection of subclinical abnormalities in cerebral blood flow could be of great value in identifying diabetic patients at risk of stroke. The aim of this study was to assess the contribution of semiquantified post-acetazolamide technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (99mTc-HMPAO SPET) in 15 diabetic patients with no clinical history of central neurological disease. After baseline 99mTc-HMPAO SPET, a second SPET scan was acquired after activation of the cerebrovascular reserve (CVR) with an injection of 1 g of acetazolamide (post-ACZ SPET). Semiquantitative analysis was made in 16 regions of interest (ROIs) drawn for each of the three supratentorial slices selected, and in two ROIs in the infratentorial slice. The CVR was calculated in each ROI by subtracting the decay-corrected baseline images from those obtained in the post-ACZ SPET and expressed as the percent increase in the average counts between the two scans. Baseline perfusion and CVR values in the study group were compared with the corresponding values in a control group. Of 750 cortical ROIs studied, 332 showed a decreased CVR (44.3%). The baseline perfusion SPET study showed hypoperfusion in 65 ROIs (8.6%) and hyperperfusion in 56 (7.4%). Of the 65 hypoperfused regions, 66.2% had a normal CVR and 33.8% had a decreased CVR, whereas of the 56 hyperperfused regions, 51.8% had a CVR within normal limits and 48.2% showed a decreased CVR. In conclusion, in comparison with baseline 99mTc-HMPAO SPET, the ACZ activation test provided additional information in the study of cerebrovascular impairment, and allowed characterisation of the subclinical abnormalities in the population studied. The technique may therefore prove useful in evaluating future preventive strategies for stroke in diabetic patients.

[Abdominal fat assessment by magnetic resonance: comparison with biometric profiles and cardiovascular risk markers]

BACKGROUND

Obesity is associated with numerous metabolic complications and cardiovascular disease. Magnetic Resonance (MR) imaging provides fair resolution of fat distribution, its quantification by semiautomatic methods being feasible. Our purpose was to analyze abdominal fat deposition by MR imaging and quantify its relative distribution in 50 obese patients. RESULTS were then related to anthropometric measures and cardiovascular risk markers.

PATIENTS AND METHOD

Six axial T1-weighted abdominal images were obtained from each patient and transferred to a PC. A software (ASYMED 3.0; Valencia) was used to analyze the images and quantify relative fat deposition. Comparison of MR results with several cardiovascular risk markers was performed using unpaired data Student t-test. Significance level was defined as a P < 0.05.

RESULTS

12% of patients showed predominant intra-abdominal fat deposition.Significant differences were found with regard to age, waist-hip ratio and average serum levels of total cholesterol, LDL, VLDL,triglycerides and apoprotein B between intra-abdominal deposition versus subcutaneous fat deposition.

CONCLUSION

MR imaging allows estimation of abdominal fat deposition and its relative distribution. There is a significant relationship between a predominant intra-abdominal fat deposition and an atherogeniclipid profile.

[Epidemiology of hemorrhagic cerebrovascular disease in the central region of Cuba]

INTRODUCTION

Cerebrovascular diseases are the third most important cause of death in Cuba. Among the programmes given priority by the Cuban Ministry of Public Health and the World Health Organization (WHO), hemorrhagic disorders are the most lethal .

OBJECTIVE

To determine the behaviour of hemorrhagic cerebrovascular disease in the central region of Cuba.

PATIENTS AND METHODS

. An exploratory, descriptive, retrospective study in which 1,401 clinical histories were reviewed. The variables being investigated were then processed using the computer data processor EPINFO 6.0 to determine the mean, standard deviation and chi squared.

RESULTS

An annual incidence rate of 84.03 per 100,000 persons was seen for hemorrhagic cerebrovascular disease; 54.16 and 29.86 per 100,000 persons respectively for intracerebral hemorrhage and subarachnoid hemorrhage; and total mortality of 68.95%. The disorder was associated with possible meteorological factors and the highest percentage was due to intracerebral hemorrhage with 64.45%. Arterial hypertension was the most intensely studied risk marker (p< 0.01). Most cases were elderly (p< 0.001). Surgical treatment was given to 81 patients with subarachnoid hemorrhage, with a predominance of malformations of the middle and anterior cerebral arteries. Treatment was based on depletion using Manitol and calcium antagonists. A considerable number of patients required mechanical ventilation and vaso active drug support. Most were attended in Intermediate Polyvalent Treatment Units and the main complication was sepsis.

CONCLUSIONS

There is a high mortality from hemorrhagic cerebrovascular disease in the central region of Cuba, and once the diagnosis has been made the prognosis is usually poor. The patients included in the programme of attention for subarachnoid haemorrhage showed promising results.

Usefulness of adding multiplex nested-polymerase chain reaction assay of cerebrospinal fluid samples to routine diagnostic testing for herpesvirus encephalitis

The present study was conducted to assess the usefulness of adding the multiplex nested-polymerase chain reaction assay of cerebrospinal fluid samples to routine diagnostic testing for herpesvirus encephalitis and to monitor the efficacy of therapy. Cerebrospinal fluid samples from 45 patients with presumed herpesvirus encephalitis were tested for herpes simplex virus, varicella-zoster virus, cytomegalovirus, human herpesvirus 6, and Epstein-Barr virus. Ten of the 45 patients were positive for a virus using the polymerase chain reaction assay: herpes simplex virus (n=5), Epstein-Barr virus (n=3), and herpes simplex virus plus the Epstein-Barr virus (n=2). Cerebrospinal fluid from two patients who had undergone acyclovir therapy gave negative results. Analysis of cerebrospinal fluid by multiplex polymerase chain reaction can be useful for establishing an accurate diagnosis and as a marker of the efficacy of therapy.

Atrial activity enhancement by Wiener filtering using an artificial neural network

This paper describes a novel technique for the cancellation of the ventricular activity for applications such as P-wave or atrial fibrillation detection. The procedure was thoroughly tested and compared with a previously published method, using quantitative measures of performance. The novel approach estimates, by means of a dynamic time delay neural network (TDNN), a time-varying, nonlinear transfer function between two ECG leads. Best results were obtained using an Elman TDNN with nine input samples and 20 neurons, employing a sigmoidal tangencial activation in the hidden layer and one linear neuron in the output stage. The method does not require a previous stage of QRS detection. The technique was quantitatively evaluated using the MIT-BIH arrhythmia database and compared with an adaptive cancellation scheme proposed in the literature. Results show the advantages of the proposed approach, and its robustness during noisy episodes and QRS morphology variations.

[Primary orthostatic tremor: slow harmonic component as responsible of inestability]

BACKGROUND

Orthostatic tremor (OT) is clinically defined as a tremor of the lower limbs and trunk on walking. It bears a significant functional impairement. Although the term orthostatic tremor was first used by Heilman in 1984, Pazzaglia et al had previously described some cases in 1970. Despite the fact that the pathophysiology of this entity is not fully known, the presence of a central oscillator is generally accepted as being responsible. A high frecuency tremor, between 13 and 18 Hz, constitutes an almost patognomonic finding, and treatment with clonazepam usually improves the symptoms.

PATIENT AND METHOD

We present a patient who described his symptoms as "cramps" in lower limbs and trunk on standing up, which were relieved on walking or resting.

RESULT

This clinical presentation together with a neurophysiological recording of the tremor showing an activity of lower frequency (8 Hz) combined with the usual higher frequency (16 Hz) and above all the clear amelioration of symptoms when treated with gabapentin, i.e. resolution of the low frequency tremor without changes in the 16 Hz tremor, were the peculiar features of this case which merits discussion.

CONCLUSIONS

The slow component of the orthostatic tremor is crucial in this case. The improvement with gabapentin is explained by the disappearance of this slow c

Expression of TCF, TPF/YY1, and the Sp family transcription factors in rabbit endometrium throughout pregnancy

BACKGROUND

TCF, TPF/YY1, and the Sp family are specific transcription factors that bind sequences found within the uteroglobin (UG) gene promoter region that are necessary for transcription. To date, UG gene expression and regulation in vivo are not fully understood. The purpose of this study was to assess the expression patterns of these factors in the rabbit endometrium throughout pregnancy.

METHODS

Endometrial nuclear extracts were obtained from female rabbits on days 0, 3, 5, 7, 15, and 28 after mating. Transcription factor expression was assessed by DNA-protein binding assays using endometrial nuclear proteins and specific oligonucleotides. Band shifts were observed on 4% acrylamide gels and analyzed by densitometry.

RESULTS

The expression patterns of the transcription factors analyzed here differed, as TPF/YY1 and Sp3/SpR-2 were expressed constitutively while TCF and Sp1 showed variable expression patterns throughout pregnancy.

CONCLUSIONS

Our results suggest that UG gene expression in the intact pregnant rabbit is controlled by two constitutive and two regulated factors, and that the DNA-binding sites are located at the TATA box and the GT1 sites within the gene promoter.

Peroxisomal proliferation induced by treatment with clofibrate in a patient with a peroxisomal disease

The induction of peroxisomal proliferation in liver parenchymal cells of rats fed a diet containing clofibrate, a hypolipidemic drug, is a well-established event. However, the available data on human hepatocytes in vivo and in vitro indicate that agents that induce peroxisomal proliferation in rats and mice have no effect on human liver cells. The authors are reporting the case of a patient with clinical and laboratory diagnosis of X-linked-adrenoleukodystrophy. In an initial liver biopsy, a reduced volume fraction of peroxisomes was found (Vv. = .012) after a morphometric analysis, initiating treatment with clofibrate at a dose of 1.5 g/d. The administration of clofibrate was maintained for 7 yr. Liver biopsies were taken after 2, 4, and 7 yr, to follow the peroxisomal response. Results demonstrated a 500% increase in peroxisomal Vv. (.060) after 2 yr of treatment, compared with the pretreatment Vv. In subsequent biopsies, the peroxisomal Vv. value was maintained at 225 and 183% increases above the pretreatment biopsy (.027 and .022, respectively).

Effect of ketamine on spinal cord nociceptive transmission in normal and monoarthritic rats

The effects of systemically and intrathecally administered ketamine on spinal wind-up of normal and monoarthritic rats were studied by using C-fiber reflex responses evoked by repetitive (0.6 Hz) electric stimulation. Both systemic and intrathecal ketamine induced dose-dependent depression of wind-up activity in normal rats, as revealed by the dose-related inhibitory effects of the drug. At the same intraperitoneal doses, ketamine produced a greater inhibitory effect on wind-up activity of monoarthritic rats, compared to normal animals. The intrathecal administration of ketamine also produced wind-up inhibition, the efficacy being higher in the monoarthritic rats. Results indicate that ketamine depresses spinal wind-up, specially in rats submitted to chronic pain, probably due to its antagonistic properties on dorsal horn NMDA receptors, which play a crucial role in the maintenance of chronic pain.

Lesion of the bulbospinal noradrenergic pathways blocks desipramine-induced inhibition of the C-fiber evoked nociceptive reflex in rats

Desipramine-induced inhibition of spinal cord nociceptive transmission was studied in rats with or without lesion of the bulbospinal noradrenergic system by recording the C-fiber evoked nociceptive reflex from a hind limb. Bulbospinal noradrenergic projections were lesioned by injecting intrathecally 20 microg of 6-hydroxydopamine 2 weeks before the electrophysiological experiments. Results show that desipramine (5, 10 and 20 mg/kg intraperitoneally) produced dose-dependent inhibition of the C reflex response duration in rats having intact noradrenergic bulbospinal systems. The inhibitory effect of desipramine was reduced or even abolished in rats pre-treated with 6-hydroxydopamine. In addition, [3H]-noradrenaline uptake was significantly lower in spinal cord slices arising from 6-hydroxydopamine lesioned animals, as compared to that from intact rats. These observations support the notion that the antinociceptive activity of antidepressants with noradrenergic selectivity depends on a normal rate of endogenous noradrenaline released by bulbospinal neurons.

Nutritional evaluation of ethanol-extracted lentil flours

Lentil flours were extracted with 80% ethanol at 25 and 50 degrees C for 1, 2, or 3 h. The various nitrogen fractions, soluble carbohydrates, three amino acids (Lys, His, and Tyr), available lysine, protein digestibility, and vitamins B(1) and B(2) were analyzed to evaluate the effect of extraction. Extraction resulted in an increase in the total nitrogen content of the extracted flours, with extraction temperature affecting the nature of the nitrogen (protein or nonprotein) content. There was also a large reduction in the oligosaccharides of the raffinose family, although the effect of temperature was appreciable only in the case of stachyose. There was hardly any effect on the concentrations of the amino acids analyzed or on protein digestibility; however, a positive correlation between protein digestibility and the available lysine was recorded in the samples. The vitamin B(1) and B(2) contents underwent variable decreases depending on extraction temperature.

Antinociceptive effect of clomipramine in monoarthritic rats as revealed by the paw pressure test and the C-fiber-evoked reflex

The antinociceptive effect of clomipramine was studied in monoarthritic rats by using the paw pressure test and the C-fiber-evoked reflex. Monoarthritis was produced by intra-articular injection of complete Freund's adjuvant into the tibio-tarsal joint. Joint circumference as well as vocalization threshold to graded paw pressure were evaluated weekly during a 14-week period after the intra-articular injection. At week 8, monoarthritic and vehicle-injected control rats were given either clomipramine or saline and both the paw pressure threshold and inhibition of the C-fiber-evoked reflex response were evaluated. Results showed that (i) 1.5, 3.0, and 6.0 mg/kg, i.v. of clomipramine induced significantly greater dose-dependent antinociception to paw pressure testing in the monoarthritic group, as compared to the control one; and (ii) 0.75, 1.5, 3.0, and 6.0 mg/kg, i.v. of clomipramine exerted significantly higher dose-dependent inhibition of the C-reflex activity in monoarthritic rats than in controls. Results suggest that the higher sensitivity to clomipramine in monoarthritic rats could be related to adaptive changes occurring in monoamine metabolism or in other neurotransmitter systems during chronic pain.

[Adult polyglucosan body disease: report of one case]

Adult polyglucosan body disease is a recently established clinicopathological entity, with few cases reported in the literature. In this paper we describe a case of a 46-year-old man who had died to a pancreatic cancer whose neuropathological study revealed a massive accumulation of polyglucosan bodies in the cerebral white matter, brainstem, cerebellum and spinal cord consistent with the adult polyglucosan body disease. We also discuss the pathological criteria used to differentiate this disease from others in which polyglucosan bodies may accumulate in the nervous system.

Oral Cerebrolysin enhances brain alpha activity and improves cognitive performance in elderly control subjects

Cerebrolysin is a porcine brain derived peptide preparation with potential neurotrophic activity. The effects of a single oral dose of the Cerebrolysin solution (30 ml) on brain bioelectrical activity and on cognitive performance were investigated in healthy elderly people. A single oral dose of Cerebrolysin induced a progressive increase in relative alpha activity power from 1 to 6 hours after treatment in almost all the brain electrodes in elderly control subjects. As compared with baseline alpha power (45.8+/-9.5%), the increase in relative alpha activity in the left occipital electrode (O1) reached significant values at 1 hour (57.2+/-8.5%; p < 0.05), 3 hours (59.4+/-7.6%; p < 0.05) and 6 hours (63.4+/-9.8%; p < 0.05) after Cerebrolysin administration. Enhancement in relative alpha power was accompanied by a generalized decrease in slow delta activity that was maximum at 6 hours after Cerebrolysin intake. A significant improvement in memory performance, evaluated with items of the ADAS cog, was also found in elderly people taken a single dose of oral Cerebrolysin (6.9+/-1.0 errors at baseline versus 4.9+/-1.0 errors after treatment; p < 0.01). This memory improvement was more evident in recognition (2.8+/-0.6 errors vs. 1.5+/-0.7 errors; p < 0.05) than in recall tasks (4.1+/-0.5 errors versus 3.4+/-0.5 errors; ns). These data indicate that Cerebrolysin potentiates brain alpha activity, reduces slow EEG delta frequencies and improves memory performance in healthy elderly humans, suggesting that this compound activates cerebral mechanisms related to attention and memory processes. According to the present results, it seems that oral Cerebrolysin might be useful for the treatment of memory impairment and brain damage in eldely subjects with or without neurodegenerative disorders.