Conditioned and unconditioned forelimb reflex systems in the cat: involvement of the intermediate cerebellum

 Temporary inactivation of the cerebellar interposed nuclei was used to assess the role of the intermediate cerebellum in the performance of forelimb cutaneo-muscular reflexes in the cat. The following types of reflexive responses were evaluated: the classically conditioned and unconditioned forelimb withdrawal responses and the forelimb tactile placing, hopping and magnet responses. The experiments tested the hypothesis that the intermediate cerebellum is involved in the performance of all the above forelimb reflexes. The forelimb withdrawal reflex was classically conditioned in a newly developed paradigm in which animals were first operantly conditioned to stand on four elevated platforms. Trained animals were microinjected with a γ-aminobutyric acid (GABA) agonist, muscimol, in the interposed nuclei, and the effects of inactivation of the intermediate cerebellar output on the forelimb reflexes were examined. The main findings of these experiments are that unilateral muscimol inactivation of the interposed nuclei in the cat abolished the expression of the classically conditioned limb flexion reflex, suppressed the performance of the unconditioned withdrawal reflex and, in parallel, downregulated the tactile placing, hopping and magnet postural responses in the ipsilateral forelimb. These observations are inconsistent with concepts indicating exclusive involvement of the intermediate cerebellum in the classically conditioned reflexes elicited by aversive stimuli. On the contrary, they support the hypothesis of a more global involvement of this structure in learned and unlearned defensive flexion reflexes and in automatic postural response systems. Received: 29 July 1996 / Accepted: 26 September 1996     

Mechanisms of fatigue in normal intercostal muscle and muscle from patients with myasthenia gravis

Fatigue mechanisms in normal intercostal muscle and muscle from patients with myasthenia gravis (MG) were evaluated by monitoring the compound muscle action potential (CMAP) and tetanic tension responses to repetitive nerve or muscle stimulation in vitro. When fatigue was induced by nerve stimulation at 30 Hz for 0.5 s every 2.5 s, about half of the original tension decreased after 30 min in normal muscle and 5 min in MG muscle. Analysis of the changes in area of CMAPs and tension indicated that impairment of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 40%, 29%, and 31% of fatigue in normal muscle, and 83%, 0%, and 17% of fatigue in MG muscle. When fatigue was induced by muscle stimulation at 30 Hz, tension declined by a quarter after 30 min in normal muscle, but by a half after 17 min in MG muscle. Impairment of muscle membrane excitation and E-C coupling and contractility accounted for 58% and 42% of fatigue in normal muscle, and 22% and 78% of fatigue in MG muscle. Thus, fatigue of normal muscle is caused by impairment of at least four processes, and enhanced fatigue of MG muscle is caused by greater impairment of neuromuscular transmission, E-C coupling, and contractility. © 1993 John Wiley & Sons, Inc.     

Regulation of local sweating in sleep-deprived exercising humans

Summary Thermoregulatory sweating [total body (m _sw,b), chest (m _sw,c) and thigh (m _sw,t) sweating], body temperatures [oesophageal (T _oes) and mean skin temperature (T _sk)] and heart rate were investigated in five sleep-deprived subjects (kept awake for 27 h) while exercising on a cycle (45 min at approximately 50% maximal oxygen consumption) in moderate heat (T _air andT _wall at 35° C. Them _sw,c andm _sw,t were measured under local thermal clamp (T _sk,1), set at 35.5° C. After sleep deprivation, neither the levels of body temperatures (T _oes,T _sk) nor the levels ofm _{sw, b},m _{sw, c} orm _{sw, t} differed from control at rest or during exercise steady state. During the transient phase of exercise (whenT _sk andT _sk,1 were unvarying), them _{sw, c} andm _{sw, t} changes were positively correlated with those ofT _oes. The slopes of them _{sw, c} versusT _oes, orm _{sw, t} versusT _oes relationships remained unchanged between control and sleep-loss experiments. Thus the slopes of the local sweating versusT _oes, relationships (m _{sw, c} andm _{sw, t} sweating data pooled which reached 1.05 (SEM 0.14) mg·cm^–2·min^–1°C^–1 and 1.14 (SEM 0.18) mg·cm^–2·min^–1·°C^–1 before and after sleep deprivation) respectively did not differ. However, in our experiment, sleep deprivation significantly increased theT _oes threshold for the onset of bothm _{sw, c} andm _{sw, t} (+0.3° C,P<0.001). From our investigations it would seem that the delayed core temperature for sweating onset in sleep-deprived humans, while exercising moderately in the heat, is likely to have been due to alterations occurring at the central level.     

Black/white comparisons of deaths preventable by medical intervention: United States and the District of Columbia 1980-1986

Blacks in the US experience increased mortality (1113 versus 745 per 100,000 males; 631 versus 411 per 100,000 females) and decreased life expectancy (63.7 years versus 70.7 years for males; 72.3 years versus 78.1 years for females); compared to Whites. In an effort to determine if the excess mortality among Black Americans might be explained by differences in access or quality of health care services, we performed a race-specific analysis of conditions for which mortality is largely avoidable given timely and appropriate medical care. Using methodology proposed by Rutstein and Charlton, mortality due to 12 causes was evaluated including tuberculosis, cervical cancer, Hodgkin's disease, rheumatic heart disease, hypertensive heart disease, acute respiratory disease, pneumonia and bronchitis, influenza, asthma, appendicitis, hernias and cholecystitis. In the US, during 1980 to 1986, an average of 17,366 deaths and 286,813 years of potential life (YPLL) before age 65 were lost each year due to all 12 sentinel causes combined. Of these causes, hypertensive heart disease, pneumonia and bronchitis, cervical cancer and asthma accounted for the greatest number of deaths. The mortality rate for all 12 causes combined among Blacks was 4.5 times that of Whites. The highest relative rates among Blacks compared to Whites were observed for tuberculosis, hypertensive heart disease and asthma. The overall mortality rate in the District of Columbia for the selected causes was 3.7 times the national rate. Compared to national rates, statistically significant elevated rates in the District were observed for tuberculosis, hypertensive heart disease and pneumonia and bronchitis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of endoscopic papillosphincterotomy in the treatment of acute pancreatitis

The authors describe results of using endoscopic papillosphincterotomy in 100 patients with acute pancreatitis. Methods of endoscopic papillosphincterotomy and endoscopic papillosphincterowirsungotomy are presented. The effectiveness of the treatment was 96%. Operative procedures on emergency made up 1%, lethality-1%, complications-3% of the cases.     

The statistics on malignant neoplasms of the urinary and male genital organs in 1987 in the USSR

The USSR statistics on malignant neoplastic diseases of the urinary system and male sexual organs which comprised 5.7 per cent in the total mortality was presented for the first time. More than a 50 per cent increment in the death rate from these tumors was documented between 1975 and 1987. Annually, prostatic carcinoma is diagnosed in almost 10 thousand patients and cancer of the urinary bladder in 15 thousand patients. Maximal prevalence of the disease has been recorded in the Baltic republics, the Ukraine and Byelorussia. The detection rate of the aforementioned diseases, Stages I-II, is about 40 per cent. The estimate revealed that the total number of the registered oncological patients was 100 thousand persons. The problems in organization of the oncological care system, material and technical supplies and professional training should be considered.