Contextual modulation of synchronization to random dots in the cat visual cortex

Synchronization of neuronal activity has been proposed as a binding mechanism for integration of image properties into one coherent percept. In the present study, we investigated the contextual modulation of synchronization to random dot patterns. Coherent motion of random dots evoked well synchronized responses in area 17 of anaesthetized cats when the stimulus was presented in the compound receptive field of recorded sites. Gradually changing the directional coherence of random dots in the surround while maintaining fully coherent motion of the stimulus in the receptive field significantly suppressed synchronization of neuronal activity for some stimulus conditions. However, usually one or two peaks of increased synchronization were found in the surround coherence tuning curves with low (8–12%) and/or moderate (25–50%) coherence in the surround. At the population level, synchronization was significantly depressed with incoherent motion in the receptive field and when both the surround and the receptive field were jointly stimulated with 0% coherence. The intriguing finding was the discovery of two distinct groups of cells with opposite synchronization changes dependent on the presence or absence of significant synchronization in their spontaneous activity. The latter group of neurons showed peaks of increased synchronization with lower surround coherence, thus probably being more sensitive to the direction of the surround motion. Overall, our findings support the notion that binding of stimulus properties can be achieved by synchronized activity of cortical cells. However, our findings go further than the original hypothesis of feature binding by synchrony to show that synchronization of cortical activity may be directly related to the decision making processes, which in turn are related to the threshold of perception of coherent motion.     

Anxiety during pregnancy and fetal attachment after in-vitro fertilization conception

The aim of this study was to compare 70 couples who had conceived by in- vitro fertilization (IVF) with 63 matched controls for the prevalence of anxiety and quality of attachment to the baby during pregnancy. Results for mothers showed no group differences using a global measure of anxiety, the Spielberger State-Trait Anxiety Inventory. However, pregnancy-specific measures revealed significantly higher levels of anxiety in IVF mothers about the survival and normality of their unborn babies, about damage to their babies during childbirth and about separating from their babies after birth. When IVF mothers were differentiated according to the number of treatment cycles, more differences in anxiety level were revealed, with most increases occurring in mothers who had experienced two or more treatment cycles. IVF fathers did not differ from controls on the global anxiety measure. No data on pregnancy-specific anxiety were available for fathers. Neither IVF mothers nor IVF fathers differed from controls on measures of attachment to the baby during pregnancy. Results are discussed in the context of the need for researchers to employ differentiated and issue-specific measures to identify concerns that may be unique to IVF couples. Clinical implications regarding the need for psychological support during pregnancy are also discussed.      

Feline leukaemia virus: protective immunity is mediated by virus-specific cytotoxic T lymphocytes

Feline leukaemia virus (FeLV) nucleic acid vaccination of domestic cats affords protection against viraemia and the development of latency without inducing antiviral antibodies.1 To determine the contribution of cell-mediated immunity to the control of virus replication and clearance from the host, FeLV-specific cytotoxic T lymphocyte (CTL) responses were compared in vaccine-protected, transiently viraemic, and persistently viraemic cats. Vaccinal immunity was associated with the detection of higher levels of virus-specific effector CTL in the peripheral blood and lymphoid organs to FeLV Gag/Pro and Env antigens than those observed in unvaccinated control, persistently viraemic cats (P<0.001). Likewise, higher levels of virus-specific CTLs were also observed in transiently viraemic cats which recovered following exposure to FeLV. In cats that controlled their infection, recognition of Gag/Pro antigens was significantly higher than the recognition of Env antigens. This is the first report highlighting the very significant role that virus-specific CTL have in determining the outcome of FeLV infection in either vaccinated cats or cats recovering naturally from FeLV exposure.     

Human rabies postexposure prophylaxis during a raccoon rabies epizootic in New York, 1993 and 1994.

We describe the epidemiology of human rabies postexposure prophylaxis (PEP) in four upstate New York counties during the 1st and 2nd year of a raccoon rabies epizootic. We obtained data from records of 1,173 persons whose rabies PEP was reported to local health departments in 1993 and 1994. Mean annual PEP incidence rates were highest in rural counties, in summer, and in patients 10 to 14 and 35 to 44 years of age. PEP given after bites was primarily associated with unvaccinated dogs and cats, but most (70%) was not attributable to bites. Although pet vaccination and stray animal control, which target direct exposure, remain the cornerstones of human rabies prevention, the risk for rabies by the nonbite route (e. g., raccoon saliva on pet dogs' and cats' fur) should also be considered.     

GAD65 and insulin B chain peptide (9-23) are not primary autoantigens in the type 1 diabetes syndrome of the BB rat

To investigate whether GAD65 whole molecule, GAD65 p35 or insulin B chain peptide (amino acids 9-23) play an essential role in the pathogenesis of type 1 diabetes in the BioBreeding (BB) rat, we gave serial injections of GAD65, p35 or insulin B chain (9-23) to six groups of BB/Worcester rats. The individual antigens were administered either intrathymically on day 2 and intraperitoneally in MF 59-0 adjuvant 5 times during the first 5 weeks, or by intranasal instillation once neonatally and 5 days/week for the following 6 weeks. Control groups were injected with vehicle only. Age of onset of diabetes and degree of insulitis were not different between controls and antigen-treated rats. Rats that received GAD65 intrathymically and intraperitoneally developed high GAD65-antibody titers without altering diabetes development. In GAD65-treated animals, serum antibodies recognized epitopes at 3 sites on GAD65 in diabetic animals but only at 1 site in non-diabetic animals. GAD65-injected animals also showed a significant reduction of IFN-gamma mRNA expression in the thymus. This study provides evidence against the hypothesis that GAD65 and insulin B chain peptide (9-23) are primary diabetogenic autoantigens in BB rats because immunizations with these antigens and GAD65-induced immune deviation did not alter the development of diabetes.     

Improved postoperative analgesia with preoperative piroxicam

Purpose

Piroxicam like other Non-Steroidal Anti-Inflammatory drugs can be used to provide postoperative analgesia. With a half-life of 50 hr given preoperatively its’ analgesic effect should continue postoperatively. This study compared the effects of 20 mg piroxicam given at different times in the perioperative period on postoperative analgesic requirement.

Method

Following ethical committee approval and written informed consent, 60 ASA I and II patients presenting for inpatient gynaecological laparoscopic surgery were given either 20 mg piroxicam or a placebo po two hours preoperatively, immediately before induction of anaesthesia or one hour postoperatively in a randomised double bind manner.

Results

Postoperative Visual Analogue Pain Scores were lower on admission to the recovery ward in patients given piroxicam preoperatively (Group 1), than in the other two treatment groups (groups 2 and 3). Pain scores were 2.72 vs 4.25 vs 6.67 respectively (P < 0.001). Pain scores did not differ at any other times. Time to first analgesic request was greater in the group 1 than in the other two treatment groups; 141 (61) min vs 115 (147) in Group 2 and 30 (36) min in Group 3. Nine patients in Group 1 requested further analgesia compared with 15 in Group 2 and 16 in Group 3. There were no piroxicam-induced side-effects.

Conclusion

Piroxicam given two hours preoperatively reduced pain scores, time to first analgesia and postoperative analgesic requirements compared with administration prior to induction or one hour postoperatively.