Retention of successive position reversals in rats with septal and fronto-polar lesions

Eight successive position reversals were given preoperatively to establish position reversal sets in rats. Six animals received septal lesions, six fronto-polar cortex ablations, and six normals served as a control group. During a series of eight postoperative reversals, rats with septal lesions committed significantly more errors and approach errors than normals while fronto-polar ablations had no detectable effect.     

An analysis of the VEP to luminance modulation and of its nonlinearity.

Identification of the VEP luminance modulation system was carried out using a relatively long pseudorandom binary m-sequence stimulus. The complete first order cross-correlation function provides a "fingerprint" of the nonlinearity in the time domain. Volterra kernel slices up to third order are recognized in the complete first order cross-correlation function. They all lie close to the major diagonal. Higher order kernel slices are not measurable. A cascade block model (sandwich model) analysis shows the nonlinearity to be an asymmetric rectification. Luminance increase causes a stronger response than does luminance decrease. The pre-filter gain function is low-pass. The post-filter gain function is band-pass tuned near 10 Hz. Coherency spectra are used to examine the channel structure of the system. Two channels operating near 8 and 15 Hz are easily identified. Another broad channel (or possibly multiple channels) is present above 30 Hz. In many subjects, the pseudorandom stimuli allow a complete system identification to be carried out in less than 82 sec.     

Hypothermic anticoagulation: testing individual responses to graded severe hypothermia with thromboelastography

Selective incircuit blood cooling could be an effective anticoagulation strategy during hemodialysis. However, it is currently unknown what blood temperature would ensure sufficient anticoagulation. Similarly, no information exists about potential interindividual variability in response to graded hypothermia. Therefore, the aim of this study was to analyze effects of profound hypothermia on human coagulation. Furthermore, a mathematical relationship between blood temperatures and coagulation was sought to predict individual responses to blood cooling. It was designed as a laboratory study. Thromboelastography (TEG) measurements were taken at a temperature range of 38-12°C. To enable measurements below 20°C, the TEG device was placed into an air conditioned chamber allowing for setting of the temperatures over a wide range. The data were analyzed by regression analysis for pooled and individual measurements. Decreasing temperatures always led to a progressive reduction in blood coagulation by delaying the initiation of thrombus formation, as well as by decreasing the speed of its creation and growth. However, the response to cooling was not uniform and the interindividual variability exists. The relationship between blood temperature and coagulation is not linear but exponential (parameters R and K) and sigmoid (parameter α-angle). The lower the blood temperature, the more significant effect on blood coagulation decline. To predict an individual response of the coagulation system over a wide range of temperatures, a mathematical modeling can be used.     

National prevalence survey of hospital-acquired infections in Czechoslovakia

A nationwide 1-day prevalence survey of a total of 12,260 patients in 23 hospitals across Czechoslovakia yielded 751 cases of hospital-acquired infection (HAI), a prevalence of 6.1%. Analysis of the data revealed that the prevalence of HAI amongst surgical patients was almost twice that amongst medical patients (8.2% vs. 4.4%). Persons aged over 60 on the urological and surgical wards were at highest risk of acquiring infection. The most frequent site of HAI was the urinary tract (25%), followed by surgical wounds (15%) and the upper respiratory tract (13%). Fifty per cent of infection in gynaecological patients occurred within 6 days of admission compared with 15% in urological patients, and a wide variation was seen in other specialties.     

The thermal origin of spontaneous activity in the Limulus photoreceptor

1. Discrete depolarizations of the photoreceptor cell membrane called discrete waves occur spontaneously and in response to illumination in the eye of the horseshoe crab, Limulus. Each light induced discrete wave is caused by the absorption of a single photon.2. The frequencies of spontaneous and light induced discrete waves were studied at different temperatures from 0 to 25 degrees C using a new method of counting them to avoid errors due to their temporal overlap.3. The frequency of spontaneous discrete waves followed the Arrhenius relationship with activation energy equal to 48.6 kcal.4. The frequency of the discrete waves caused by a fixed level of steady illumination was not significantly changed when the temperature of the cell was changed.5. The relationship of the frequency of spontaneous discrete waves to temperature was compared to a prediction based on the relationship of the quantum relative spectral sensitivity of the Limulus eye to the temperature of the eye. The prediction was in good agreement with observation and suggests that spontaneous discrete waves result from thermally induced cis to trans isomerizations of visual pigment molecules.     

Epicutaneous immunization with myelin basic protein protects from the experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) with limited treatment modalities. One of the experimental methods that protect from autoimmune diseases is oral tolerance. However, this method failed to show therapeutic efficacy in clinical trials. In our previous work, we found that epicutaneous (ec) immunization with a protein antigen induces a state of profound immunosuppression that inhibits inflammatory response in contact sensitivity (CS), experimental autoimmune encephalomyelitis (EAE) in B10.PL mice that develop chronic form of disease, and also delayed allogeneic skin graft rejection. In the current work, we showed that ec immunization with MBP protects from relapsing and remitting EAE. Protection from the disease correlated with decreased number of mononuclear cells isolated from CNS. Additionally, histological examination showed only a slight mononuclear cell infiltration in spinal cords of mice ec immunized with MBP when compared to positive control where animals were ec treated with PBS before disease induction.     

Chlorocyclinones A-D, chlorinated angucyclinones from Streptomyces sp. strongly antagonizing rosiglitazone-induced PPAR-gamma activation

In the course of our screening to identify novel PPAR-gamma modulators for the potential treatment of type 2 diabetes, four new chlorinated angucyclinones, chlorocyclinones A-D ( 1- 4), were isolated from the mycelium of Streptomyces sp. strain DSM 17045. Their structures were established by spectroscopic methods. Chlorocyclinones antagonize rosiglitazone-induced peroxisome proliferator-activated receptor gamma (PPAR-gamma) activation with IC 50's < 0.4 microM in vitro using an AlphaScreen assay and are able to displace rosiglitazone from the PPAR-gamma ligand-binding domain (LBD) in a scintillation proximity assay (SPA). The compounds proved to be active in a cell-based reporter gene assay as well, antagonizing rosiglitazone-induced PPAR-gamma activity with IC 50 values between 0.60 and 7.0 microM. Chlorocyclinone C ( 3) exhibited the most potent activity in all assays.