Functional Anatomy of Visuomotor Skill Learning in Human Subjects Examined with Positron Emission Tomography

The present study was designed to examine patterns of regional cerebral blood flow (CBF) associated with the learning of a repeated visuomotor sequence both in the early and late phases of the acquisition process. In addition, changes in blood flow related to the implicit versus explicit aspects of learning such a skill were investigated. Fourteen normal control subjects were scanned while performing the task (i) in both early and advanced learning stages of the visuomotor sequence; (ii) after having acquired explicit knowledge of the sequences; and (iii) in two control conditions (perceptual and random sequence). Subtraction of the random condition from the highly learned condition revealed specific areas of activity in the right ventral striatum and dentate nucleus of the cerebellum. Blood flow changes in the right hemisphere were also seen in the medial posterior parietal and prestriate regions, as well as in the anterior cingulate cortex. Finally, once the subjects had acquired explicit knowledge of the embedded sequence that was presented in the highly learned condition, increased CBF activity was observed only in the mid-ventrolateral frontal area in the right hemisphere. These findings confirm that both the striatum and the cerebellum are involved in the implicit acquisition of a visuomotor skill, especially in the advanced stages of the learning process, and furthermore that the ventrolateral prefrontal cortex contributes preferentially to the declarative aspect of this task.     

Protection Against Chemically-Induced Oxidative Gastrointestinal Tissue Injury in Rats by Bismuth Salts

Oxygen free radicals (OFR) are implicated in thepathogenesis of stress, chemically induced gastriclesions, and gastrointestinal injury. Theconcentration-dependent scavenging abilities of bismuthsubsalicylate (SBS), colloidal bismuth subcitrate (CBS), andselected OFR scavengers, including superoxide dismutase(SOD), catalase, mannitol, and allopurinol were examinedagainst biochemically or chemically generated superoxide anion, hydroxyl radical, andhypochlorite radical plus hypochlorous acid based on achemiluminescence assay. Furthermore, both gastric (GM)and intestinal mucosa (IM) were individually exposed in vitro to these free radical generatingsystems, and the concentration-dependent protectiveabilities of SBS and CBS against lipid peroxidation (LP)were compared with selected OFR scavengers. In addition, 24-hr fasted rats were orally treated with thenecrotizing agents 0.6 M HCl, 0.2 M NaOH, 80% ethanol,and aspirin (200 mg/kg). The extent of tissue injury inthe GM and IM was determined by assessing LP, DNA fragmentation, and membrane microviscosity.Dose- and time-dependent in vivo protective abilities ofCBS (100 mg/kg) and SBS (15 mg/kg) were also assessed.Following incubations with superoxide anion and hydroxyl radical generating systems in thepresence of 125 mg SBS/liter, approximately 47% and 61%inhibitions were observed in the chemiluminescenceresponse, respectively, while 48% and 46% inhibitions were observed with 125 mg CBS/liter. SBS andCBS exerted similar abilities towards hypochloriteradical plus hypochlorous acid. Approx. 3.1- and3.7-fold increases in LP were observed in the GM and IMof rats following oral administration of 0.6 MHCl. Pretreatment of the rats with SBS and CBS decreased0.6 M HCl-induced LP in the GM by approx. 39% and 27%,respectively, with similar decreases in LP in the IM. SBS exhibited better protectiveabilities towards 0.6 M HCl and 0.2 m NaOH-induced GMand IM injury as compared to CBS. SBS and CBS providedsimilar protection towards 80% ethanol-induced gastric injury, while CBS exerted a superior protectiveability towards aspirin-induced gastric injury. Theresults demonstrate that both SBS and CBS can scavengereactive oxygen species and prevent tissue damage produced by OFR.     

The immunopathology of M cells

Conclusions Mucosal epithelia have two functions, which at first glance seem at variance with each other — maintenance of a barrier and uptake of antigens. The M cell is a unique solution to this problem. However, it also provides many mucosal and systemic pathogens with a convenient portal of invasion, and may also be the point of uptake of detrimental antigens, such as carcinogens and those that induce autoimmune disease. Much remains unknown about the functions of M cells and the precise nature of their interactions with pathogens. Determinants of pathogen tropism for M cells, in particular anatomic sites, must be elucidated before we can proceed to the task of modulating M cell antigenic uptake to enhance absorption and presentation of vaccines and to reduce systemic penetration of allergens and pathogenic microorganisms. Research in this area would be considerably advanced by the development of techniques to induce and maintain differentiated M cells in vitro, and the production of monoclonal antibodies specific for cells of this lineage. Irrespective of these gaps in our current knowledge, it has become increasingly apparent that the M cell may be of paramount importance in the initiation of colonization by many, if not all, important human and animal mucosal pathogens.     

Relationship among level of distraction, evoked potentials, spinal cord ischemia and integrity, and clinical status in animals

Somatosensory evoked potentials (SEPs) and neurogenic-motor evoked potentials (NMEPs) were recorded after overdistraction of the spinal cord at T5-T6, T12-L1, or L3-L4. Measures of spinal cord perfusion and clinical status were also administered. Results indicated that stiffer spinal segments allowed less distraction than more flexible segments. SEPs and NMEPs were lost quickly after overdistraction in stiff segments and slowly in more flexible segments. However, SEPs were less sensitive than NMEPs to effects from overdistraction. Spinal cord perfusion and integrity were consistent with reduced perfusion and structural damage after overdistraction in stiff segments; extremely reduced perfusion but no structural changes in more flexible segments. The application of these results to the clinical situation was provided.     

THE INTRODUCTION OF PATIENT-CONTROLLED ANALGESIA INTO AN ISOLATED RURAL HOSPITAL

This study investigated the feasibility of using patient-controlled analgesia (PCA) effectively in a small 70 bed isolated rural hospital. The tirst 50 patients to use a Bard PCA 1, in the Port Lincoln Hospital, South Australia, were studied. The patients consumed morphine at a mean rate of 1.24 mg/h and used PCA for a mean of 48 h. Thirty-eight per cent of patients required treatment for nausea and other complications which is similar to the rate of those in other published series. Visual analogue pain scores showed excellent pain control, generally without evidence of oversedation; however, there was one episode of respiratory depression. Seventy-eight per cent of patients reported that their pain was relieved most or all of the time. The study demonstrated that a PCA service provided by nursing staff, the GP anaesthetist and rural surgeons is feasible in an isolated rural hospital.     

Recent patterns of growth in radiation therapy facilities in the United States: a patterns of care study report.

The Patterns of Care Study conducted its seventh survey of radiation oncology facilities with megavoltage equipment. The aims were to identify the basic structural characteristics of the radiation oncology specialty, to allow comparison with previous surveys, to identify trends in the patterns of equipment and personnel usage, and to measure the capabilities of facilities to deliver modern radiotherapy. All radiation oncology facilities in the United States and Puerto Rico were surveyed. Multiple mailings and calls yielded identification of and responses from virtually all facilities doing megavoltage radiotherapy. The survey collected information on equipment, patient load, personnel, and types of procedures performed. The complete census was reviewed, summarized, and compared to previous surveys. Results for 1990 showed 1321 facilities, (938 hospital based, 350 freestanding, 33 federal), 492120 new patients, and 2397 treatment machines (1893 linear accelerators or betatrons and 504 cobalt machines). The number of facilities and total machines increased rapidly with most of the increase in facilities occurring in the freestanding category. The number of cobalt units declined, while the number of linear accelerators increased. The results also showed that 6% of facilities did not have the capability of simulating patients and 7% of facilities did not have treatment planning capability. Of all facilities 9% reported doing intraoperative radiation therapy and 18% doing hyperthermia. For recent years in the specialty of radiation oncology the number of facilities and treatment machines increased at a more rapid rate than the number of new patients.