Neurons of the inferior olive respond to broad classes of sensory input while subject to homeostatic control

KEY POINTS

Purkinje cells in the cerebellum integrate input from sensory organs with that from premotor centres. Purkinje cells use a variety of sensory inputs relaying information from the environment to modify motor control. Here we investigated to what extent the climbing fibre inputs to Purkinje cells signal mono- or multi-sensory information, and to what extent this signalling is subject to recent history of activity. We show that individual climbing fibres convey multiple types of sensory information, together providing a rich mosaic projection pattern of sensory signals across the cerebellar cortex. Moreover, firing probability of climbing fibres following sensory stimulation depends strongly on the recent history of activity, showing a tendency to homeostatic dampening.

ABSTRACT

Cerebellar Purkinje cells integrate sensory information with motor efference copies to adapt movements to behavioural and environmental requirements. They produce complex spikes that are triggered by the activity of climbing fibres originating in neurons of the inferior olive. These complex spikes can shape the onset, amplitude and direction of movements and the adaptation of such movements to sensory feedback. Clusters of nearby inferior olive neurons project to parasagittally aligned stripes of Purkinje cells, referred to as 'microzones'. It is currently unclear to what extent individual Purkinje cells within a single microzone integrate climbing fibre inputs from multiple sources of different sensory origins, and to what extent sensory-evoked climbing fibre responses depend on the strength and recent history of activation. Here we imaged complex spike responses in cerebellar lobule crus 1 to various types of sensory stimulation in awake mice. We find that different sensory modalities and receptive fields have a mild, but consistent, tendency to converge on individual Purkinje cells, with climbing fibres showing some degree of input-specificity. Purkinje cells encoding the same stimulus show increased events with coherent complex spike firing and tend to lie close together. Moreover, whereas complex spike firing is only mildly affected by variations in stimulus strength, it depends strongly on the recent history of climbing fibre activity. Our data point towards a mechanism in the olivo-cerebellar system that regulates complex spike firing during mono- or multi-sensory stimulation around a relatively low set-point, highlighting an integrative coding scheme of complex spike firing under homeostatic control.

Synchronicity and Rhythmicity of Purkinje Cell Firing during Generalized Spike-and-Wave Discharges in a Natural Mouse Model of Absence Epilepsy

Absence epilepsy is characterized by the occurrence of generalized spike and wave discharges (GSWDs) in electrocorticographical (ECoG) recordings representing oscillatory activity in thalamocortical networks. The oscillatory nature of GSWDs has been shown to be reflected in the simple spike activity of cerebellar Purkinje cells and in the activity of their target neurons in the cerebellar nuclei, but it is unclear to what extent complex spike activity is implicated in generalized epilepsy. Purkinje cell complex spike firing is elicited by climbing fiber activation and reflects action potential firing in the inferior olive. Here, we investigated to what extent modulation of complex spike firing is reflected in the temporal patterns of seizures. Extracellular single-unit recordings in awake, head-restrained homozygous tottering mice, which suffer from a mutation in the voltage-gated Ca_V2.1 calcium channel, revealed that a substantial proportion of Purkinje cells (26%) showed increased complex spike activity and rhythmicity during GSWDs. Moreover, Purkinje cells, recorded either electrophysiologically or by using Ca²⁺-imaging, showed a significant increase in complex spike synchronicity for both adjacent and remote Purkinje cells during ictal events. These seizure-related changes in firing frequency, rhythmicity and synchronicity were most prominent in the lateral cerebellum, a region known to receive cerebral input via the inferior olive. These data indicate profound and widespread changes in olivary firing that are most likely induced by seizure-related activity changes in the thalamocortical network, thereby highlighting the possibility that olivary neurons can compensate for pathological brain-state changes by dampening oscillations.

Impact of polychlorinated biphenyl Aroclor 1254 on testicular antioxidant system in adult rats

To clarify the reproductive toxicity of polychlorinated biphenyl compounds through determination of testicular lipid peroxidation, reactive oxygen species and enzymatic and non-enzymatic antioxidants in rats exposed to Aroclor 1254. Adult male rats were administered Aroclor 1254 at a dose of 2 mg/kg per day ip for 30 days. The rats were sacrificed 24 hours after last dosing and the serum and other tissues collected and processed for relevant determinations. The body weight and the weights of the testis, epididymis, ventral prostate and seminal vesicle and the serum testosterone and estradiol were significantly decreased in Aroclor 1254 treated rats. The testicular lipid peroxidation, hydrogen peroxide and hydroxyl radical were significantly elevated whereas, testicular antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (GST) and glutathione reductase (GR) were significantly decreased. The non-enzymatic antioxidants, vitamin C and vitamin E, were also decreased. These results suggest that Aroclor 1254 induces an increase in the lipid peroxidation, hydrogen peroxide and hydroxyl radical and diminish in the antioxidant defense system in rats, indicating that the free radical-dependent mechanism may play an important role in the testicular toxicity of polychlorinated biphenyls.

Laminar heat transfer and friction factor characteristics of carbon nano tube/water nanofluids

This paper presents an experimental investigation on the convective heat transfer and friction factor characteristics of CNT/water nanofluid through a circular tube fitted with helical screw tape inserts with constant heat flux under laminar flow condition. Nanofluids of 0.1% and 0.2% volume fractions are prepared by two step method. Thermo-physical properties like thermal conductivity and viscosity are measured by using KD2 thermal property analyzer and Brooke field cone and plate viscometer respectively. From the measurements, it is found that the viscosity increase is substantially higher than the increase in the thermal conductivity. The helical screw tape insets with twist ratios Y = 3, 2.44 and 1.78 are used to study the convective heat transfer and friction factor characteristics under laminar flow in the Reynolds number range of 520-2500. It is observed that, in a plain tube, maximum enhancement in Nusselt number for 0.1% and 0.2% volume fractions of nanofluids compared to pure water is 15% and 32% respectively. With the use of inserts, maximum enhancement in Nusselt number corresponding to twist ratios of 1.78, 2.44 and 3 are obtained as 8%, 16% and 4.6% for 0.1% volume fraction of nanofluid and 5%, 4% and 12% for 0.2% volume fraction of nanofluid when compared with water in plain tube. Thermal performance factor evaluation revealed that the values at all Reynolds number for all twist ratios and both concentration of CNT nanofluid are greater than unity which indicates that helical screw tape inserts with twist ratios considered are feasible in terms of energy saving in laminar flow.

Assessment of soft bottom polychaete diversity in Thondi, Palk Bay, India

Polychaete assemblages are relatively poorly known in comparison to other components from Indian waters. In the present study, the spatial and seasonal distributions of polychaetes were investigated in the Thondi coastal area. Polychaete assemblage structure seems to be influenced by environmental parameters, such as temperature, salinity, pH, dissolved oxygen and total organic carbon. A total of 34 polychaete species were found, of which 26 species were in station I while 22 species in station II. There was a pronounced variation in diversity of polychaetes between the studied sites. Among the families maximum percentage of species constituted by Glyceridae (12%) and minimum Owenidae (4%) at station I and in station II, the Eunicidae (14%) was maximum and Pisinidae as (4%) minimum. The population density varied from 1456 to 2456 no m(-2) in station I; 2120 to 4424 in station II and diversity index varied from 1.96 to 2.48 in station I; 2.01 to 2.53 in station II. Species richness varied from 1.21 to 1.65 in station I; 1.36 to 1.69 in station II and evenness index varied from 0.9 to 0.97 in station I; 0.91 to 0.98 in station II. BIO-ENV analysis showed that salinity, TOC and temperature as the key variables in influencing the faunal distribution.

Distribution of enteric bacteria in the sediments of Parangipettai and Cuddalore coast of India

Distribution of major groups of enteric bacteria viz., Escherichia coli, Shigella spp., Salmonella spp., Vibrio parahaemolyticus and Vibrio cholerae was studied in the sediment samples collected from different depths of 5, 15, 25 and 35 m in Parangipettai and Cuddalore coast during March, 2009 to February, 2010. Among the bacterial population in Parangipettai, V parahaemolyticus was found to be maximum with an occurrence of 55% followed by Shigella spp. (15%), V cholerae (12%), Salmonella spp. (12%) and E. coli (6%). In Cuddalore, as an oddity, Vibrio cholerae emerged as dominant species with an incidence of 60% of the total. V parahaemolyticus came next in the order with an incidence of 14%, followed by E. coli (11%), Shigella spp. (8%) and Salmonella spp. (7%). Similarly, monsoon and premonsoon seasons registered higher bacterial populations in both the regions. When the depth wise results were viewed, 5 and 15 m depths showed maximum (V parahaemolyticus 3.7 x 10 CFU g(-1) in Parangipettai; V cholera--8.6 x 10 CFU g(-1) in Cuddalore) bacterial population compared to subsequent depths. Cluster and MDS also showed distinct spatial and seasonal variations of bacterial populations in both the regions. Biota-Environment (BIO-ENV) method revealed the combinations of temperature, salinity and TOC as the best match influencing bacterial population.

Paget's disease of the mandible

Paget's disease (PD) is a chronic progressive disease of the bone characterized by abnormal bone resorption and deposition affecting either single bone (monostotic) or many bones (polyostotic) with uncertain etiology. We report a case of isolated mandibular involvement in a 65-year-old female patient, clinically asymptomatic with abnormally increased alkaline phosphatase level (1 368.1 U/l). Although prevalence of PD is common in western countries, but rare in Asian chapter, that too isolated mandibular involvement, considering this fact, we report this case of PD for documentation.

Alcohol use disorders (AUD) among tuberculosis patients: a study from Chennai, South India

BACKGROUND

Alcohol Use Disorders (AUDs) among tuberculosis (TB) patients are associated with nonadherence and poor treatment outcomes. Studies from Tuberculosis Research Centre (TRC), Chennai have reported that alcoholism has been one of the major reasons for default and mortality in under the DOTS programme in South India. Hence, it is planned to conduct a study to estimate prevalence of alcohol use and AUDs among TB patients attending the corporation health centres in Chennai, India.

METHODOLOGY

This is a cross-sectional cohort study covering 10 corporation zones at Chennai and it included situational assessment followed by screening of TB patients by a WHO developed Alcohol Use Disorders Identification Test AUDIT scale. Four zones were randomly selected and all TB patients treated during July to September 2009 were screened with AUDIT scale for alcohol consumption.

RESULTS

Out of 490 patients, 66% were males, 66% were 35 years and above, 57% were married, 58% were from the low monthly income group of 8. Age (>35 years), education (less educated), income (

CONCLUSIONS

AUD among TB patients needs to be addressed urgently and the findings suggest the importance of integrating alcohol treatment into TB care.

Collapse

Key Words Collapse

MESH Headings

• Adult
• Alcohol Drinking/epidemiology
• Alcohol-Related Disorders/complications
• Alcohol-Related Disorders/epidemiology
• Alcohol-Related Disorders/therapy
• Demography
• Female
• Humans
• India/epidemiology
• Male
• Mass Screening
• Treatment Outcome
• Tuberculosis/complications
• Tuberculosis/diagnosis
• Tuberculosis/epidemiology
• Tuberculosis/therapy

Collapse

Grants Collapse

HIV prevention interventions in Chennai, India: are men who have sex with men being reached?

India has the greatest number of HIV infections in Asia and the third highest total number of infected persons globally. Men who have sex with men (MSM) are considered by the Government of India's National AIDS Control Organization (NACO) a "core risk group" for HIV in need of HIV prevention efforts. However there is a dearth of information on the frequency of participation in HIV prevention interventions and subsequent HIV risk and other correlates among MSM in India. Recruited through peer outreach workers, word of mouth and snowball sampling techniques, 210 MSM in Chennai completed an interviewer-administered assessment, including questions about participating in any HIV prevention interventions in the past year, sexual risk taking, demographics, MSM identities, and other psychosocial variables. Bivariate and multivariable logistic regression procedures were used to examine behavioral and demographic correlates with HIV prevention intervention participation. More than a quarter (26%) of the sample reported participating in an HIV prevention intervention in the year prior to study participation. Participants who reported engaging in unprotected anal sex (UAS; odds ratio [OR] = 0.28; p = 0.01) in the 3 months prior to study enrollment were less likely to have participated in an HIV prevention program in the past year. MSM who were older (OR = 1.04; p = 0.05), kothis (feminine acting/appearing and predominantly receptive partners in anal sex) compared to panthis (masculine appearing, predominantly insertive partners; OR = 5.52, p = 0.0004), those with higher educational attainment (OR = 1.48, p = 0.01), being "out" about having sex with other men (OR = 4.03, p = 0.0001), and MSM who reported ever having been paid in exchange for sex (OR = 2.92, p = 0.001) were more likely to have reported participation in an HIV prevention intervention in the preceding year. In a multivariable model, MSM reporting UAS in the prior 3 months were less likely to have participated in an HIV prevention intervention (AOR = 0.34, p = 0.04). MSM who were older (AOR = 1.05, p = 0.05), those with higher educational attainment (AOR = 1.92, p = 0.0009), and MSM who were "out" about having sex with other men (AOR = 2.71, p = 0.04) were more likely to have reported participating in an HIV prevention program. Findings suggest that exposure to HIV prevention interventions may be protective against engaging in UAS for some MSM in India. Understanding predictors of participation in an HIV prevention intervention is helpful for identifying Indian MSM who might have had no exposure to HIV prevention information and skills building, hence allowing researchers and prevention workers to focus efforts on individuals at greatest need.

Use of benthic biodiversity for assessing the impact of shrimp farming on environment

An attempt was made to find out the impact of shrimp farm discharges on benthic diversity in the discharge point of a shrimp farm. The duration of the study was one culture period right from stocking to harvest. The results revealed that the values of environmental entities were in the safe levels. As regards nutrients, maximum value of TOC and phosphorus were recorded in the sample collected after harvest and minimum in the sample collected during culture. BIO-ENV method revealed that nitrogen, sediment salinity and TOC were manifested as best variable combination explaining faunal distribution. Polychaetes are the dominant group (50%) with 13 species followed by crustaceans (32%) with 10 species, gastropods (10%) with 2 species and bivalves (8%) with 3 species. The faunal density was found to vary in relation to months as observed in the samples which were collected during various seasons in the other areas of estuary. In line with this, diversity values were also paralleled to the faunal density. In a nut shell, the study revealed no negative impact of shrimp farming to the estuarine benthic biota.

Unseen and unheard: predictors of sexual risk behavior and HIV infection among men who have sex with men in Chennai, India

In India men who have sex with men (MSM) are stigmatized, understudied, and at high risk for HIV. Understanding the impact of psychosocial issues on HIV risk behavior and HIV infection can help shape culturally relevant HIV prevention interventions. Peer outreach workers recruited 210 MSM in Chennai who completed an interviewer-administered psychosocial assessment battery and underwent HIV testing and counseling. More than one fifth (46/210) reported unprotected anal intercourse in the past 3 months, 8% tested positive for HIV, and 26% had previously participated in an HIV prevention intervention. In a multivariable logistic-regression model controlling for age, MSM subpopulation (kothi, panthi, or double-decker), marital status, and religion, significant predictors of any unprotected anal intercourse were being less educated (adjusted odds ratio [AOR] = .54; p = .009), not having previously participated in an HIV prevention program (AOR = 3.75; p = .05), having clinically significant depression symptoms (AOR = 2.8; p = .02), and lower self-efficacy (AOR = .40; p < .0001). Significant predictors of testing positive for HIV infection were: being less educated (AOR = .53; .05) and not currently living with parent(s) (AOR = 3.71; p = .05). Given the prevalence of HIV among MSM, efforts to reach hidden subpopulations of MSM in India are still needed. Such programs for MSM in India may need to address culturally-relevant commonly cooccurring psychosocial problems to maximize chances of reducing risk for infection.

Assessment of long term status of sputum positive pulmonary TB patients successfully treated with short course chemotherapy

BACKGROUND

Long term status of pulmonary tuberculosis (PTB) patients treated with short course chemotherapy (SCC) regimens remains unknown.

OBJECTIVE

To assess the clinical, bacteriological, radiological status and health related quality of life (HRQoL) of PTB patients 14-18 years after successful treatment with SCC.

METHODOLOGY

In a cross-sectional study, cured PTB patients treated during 1986-1990 at the Tuberculosis Research Centre (TRC) were investigated for their current health status including pulmonary function tests (PFT). The St Georges respiratory questionnaire (SGRQ) was used to assess the HRQoL.

RESULTS

The mean period after treatment completion for the 363 eligible participants was 16.5 yrs (range 14-18 yrs., 84% coverage); 25 (7%) had been re-treated and 52 (14%) died. Among the investigated, 58 (29%) had persistent respiratory symptoms; 170 (86%) had radiological sequelae but none had active disease. Abnormal PFT was observed in 96 (65%) with predominantly restrictive type of disease in 66 (45%). The SGRQ scores for activity and impact were high implying impairment in HRQoL.

CONCLUSION

Assessment of long term status of cured PTB patients showed an impairment of lung functions and HRQoL highlighting the need to address these issues in the management of TB that may provide added value to patient care.

Fourier transform infrared and Raman spectral assignments and analysis of 7-amino-4-trifluoromethylcoumarin

FTIR and FT-Raman spectra of 7-amino-4-trifluoromethylcoumarin (ATMC) have been recorded in the range 4000-400 and 3500-100 cm(-1), respectively, using Bruker IFS 66 V spectrometer. A detailed vibrational analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions, relative intensities, fundamentals, overtones and combination bands. With hope of providing more and effective information on the fundamental vibrations, a normal co-ordinate analysis has been performed by assuming C(S) point group symmetry. The simple valance force field (SVFF) has been employed in normal co-ordinate analysis and to calculate the potential energy distribution (PED) for each fundamental vibration are reported. The PED contribution to each of the observed frequencies shows the reliability and precision of the spectral analysis.

Effect of Aroclor 1254 on Sertoli cellular antioxidant system, androgen binding protein and lactate in adult rat in vitro

Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental toxicants. Previous studies suggested that PCBs (Aroclor 1254) induce toxic effects including reproductive toxicity. The present study was designed to investigate the impact of Aroclor 1254 on Sertoli cellular function and antioxidant system of adult rat in vitro. Sertoli cells were isolated from adult rat testes and treated with various concentrations (10(-10) to 10(-7) M) of Aroclor 1254 for 6, 12 and 24 h. After the treatment period, cell viability was assessed and the Sertoli cellular antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), gamma-glutamyl transpeptidase (gamma-GT) and glutathione reductase (GR) and lipid peroxidation (LPO) were assayed. In addition, androgen binding protein (ABP) and lactate secretions were also quantified in Sertoli cell culture medium. Sertoli cellular viability and activity of antioxidant enzymes were significantly reduced in Aroclor 1254 (10(-10) to 10(-7) M) treatment for 6, 12 and 24 h whereas, the Sertoli cellular lipid peroxidation was significantly increased in a dose and duration dependent manner. In addition, ABP secretion diminished and lactate secretion was significantly elevated in the same manner. To conclude, the present study suggested that Aroclor 1254 disrupts Sertoli cellular metabolic functions such as ABP, lactate secretions and activity of antioxidant enzymes.

Effects of Vitamin C and E on PCB (Aroclor 1254) induced oxidative stress, androgen binding protein and lactate in rat Sertoli cells

The effect of Aroclor 1254 and the ameliorative effect of Vitamin C and E on Sertoli cell function were studied in adult male rats. The rats were administered Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received Vitamin C (100 mg/kg bw/day) while the other group received Vitamin E (50 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. Necropsy was performed at 24 h after the last injection. Sertoli cells were isolated for the estimation of enzymatic antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GST), and gamma-glutamyl transpeptidase (gamma-GT). Lipid peroxidation (LPO), hydrogen peroxide and hydroxyl radical were estimated. Sertoli cellular androgen binding protein (ABP) and lactate were also quantified. Whereas body weight, testis weight, relative weight of testis, ABP, lactate and specific activities of SOD, CAT, GPx, GR, GST, gamma-GT were all decreased, the levels of hydrogen peroxide, hydroxyl radical and LPO were significantly increased in the Sertoli cells of Aroclor 1254 treated rats. Simultaneous administration of Vitamin C or E restored these parameters to a normal range. Thus, the present study suggests that Aroclor 1254 exposure induces oxidative stress in rat Sertoli cells and furthermore that simultaneous administration of Vitamin C or E ameliorated these effects.