First report of methicillin-resistant Staphylococcus aureus Cordobes/Chilean clone involved in nosocomial infections in Brazil.

SUMMARY Methicillin-resistant Staphylococcus aureus (MRSA) commonly causes infection in hospitalized patients. Resistance is due to the acquisition of mecA gene located on the chromosomal element SCCmec and to date 12 types have been identified. Specific epidemic clones of MRSA have emerged with enhanced ability to spread within and among hospitals and to cross national boundaries. We studied 30 isolates from patients with MRSA infections at two hospitals in Porto Alegre city from April to December, 2008 and determined their SCCmec type by PCR. Representative strains were typed by PFGE. Eighteen (60%) isolates carried SCCmec type III and had PFGE profiles clonally related to the previously characterized Brazilian epidemic clone, and 11 (36·7%) isolates with pulsotypes closely related to the Cordobes/Chilean clone harboured SCCmec type I. To the best of our knowledge, this is the first report of the appearance of Cordobes/Chilean clone involved in nosocomial infection in Brazil.

Cross-transmission of vancomycin-resistant Enterococcus in patients undergoing dialysis and kidney transplant

The objective of this study was to investigate the occurrence of vancomycin-resistant Enterococcus (VRE) cross-transmission between two patient groups (long-term dialysis and kidney transplant patients). Molecular typing, by automated ribotyping with the RiboPrinter Microbial Characterization System (Qualicon, USA), was used to analyze VRE isolates from 31 fecal samples of 320 dialysis patients and 38 fecal samples of 280 kidney transplant patients. Clonal spread of E. faecalis and E. casseliflavus was observed intragroup, but not between the two groups of patients. In turn, transmission of E. gallinarum and E. faecium between the groups was suggested by the finding of vancomycin-resistant isolates belonging to the same ribogroup in both dialysis and transplant patients. The fact that these patients were colonized by VRE from the same ribogroup in the same health care facility provides evidence for cross-transmission and supports the adoption of stringent infection control measures to prevent dissemination of these bacteria.

Cross-transmission of vancomycin-resistant Enterococcus in patients undergoing dialysis and kidney transplant.

The objective of this study was to investigate the occurrence of vancomycin-resistant Enterococcus (VRE) cross-transmission between two patient groups (long-term dialysis and kidney transplant patients). Molecular typing, by automated ribotyping with the RiboPrinter Microbial Characterization System (Qualicon, USA), was used to analyze VRE isolates from 31 fecal samples of 320 dialysis patients and 38 fecal samples of 280 kidney transplant patients. Clonal spread of E. faecalis and E. casseliflavus was observed intragroup, but not between the two groups of patients. In turn, transmission of E. gallinarum and E. faecium between the groups was suggested by the finding of vancomycin-resistant isolates belonging to the same ribogroup in both dialysis and transplant patients. The fact that these patients were colonized by VRE from the same ribogroup in the same health care facility provides evidence for cross-transmission and supports the adoption of stringent infection control measures to prevent dissemination of these bacteria.

Selective impairment of excitatory pressor responses after prolonged simulated microgravity in humans.

The haemodynamic and autonomic effects of prolonged exposure to simulated microgravity were assessed non-invasively in seven healthy volunteers completing a 42-day -6 degrees head down tilt. Before, during and after head down tilt, subjects were exposed to moderate excitatory stimuli (mental arithmetic and static handgrip) to gauge possible progressive impairment of pressor responses. Before and after head down tilt, subjects were also exposed to orthostatic stress, to assess influences of simulated microgravity on orthostatic defence. Simple haemodynamics (heart rate and systolic arterial blood pressure), linear (i.e., oscillatory) components of beat-by-beat variability, non-linear properties (i.e., corrected conditional entropy (CCE)) of RR interval variability, and baroreflex slope furnished a non-invasive evaluation of autonomic regulatory mechanisms. Pressor responses to mental arithmetic and to handgrip were markedly impaired after 42 days head down tilt, whereas responses in markers of autonomic regulation were not modified. Standing, performed 8 days after head down tilt to limit the risk of syncope, still induced a variable degree of hypotension, with signs of progressively greater sympathetic activation than before head down tilt. Simulated microgravity-induced reduction of pressor responses, in spite of largely maintained autonomic activation, favours the hypothesis of a peripheral impairment of cardiovascular homeostasis. rights reserved.

Effect of postural changes on cardiovascular responses to static exercise in hypertensive human beings.

OBJECTIVE: In hypertensive patients, exaggerated increases in vascular resistance and arterial blood pressure have been reported on changing posture from supine to upright. In this study we tested the hypothesis that in hypertensive subjects, upright posture induces an increase in the vasoconstrictor and pressor responses to physical exercise. SUBJECTS AND METHODS: We studied 17 males with mild hypertension and 10 sex- and age-matched normotensives. Each performed three bouts of static handgrip at 30% maximum voluntary contraction for 2 min after 10 min of supine rest and, in sequence, after 10 min of sitting and 10 min of standing. Arterial pressure, heart rate and forearm vascular resistance were measured by Finapres and plethysmography, respectively. RESULTS: Exercise posture did not affect the mean arterial pressure and heart rate responses to static handgrip. No significant differences in these responses were observed between the hypertensives and the normotensives in any posture. In the hypertensives (n = 12), forearm vascular resistance did not change significantly from resting values during supine and sitting static handgrip but increased significantly during standing static handgrip. In the normotensives, forearm vascular resistance did not change significantly from resting values during static handgrip in any posture. The forearm vascular resistance response to the standing static handgrip was significantly greater in the hypertensives than the normotensives. The algebraic sum of forearm vascular resistance responses to postural change from sitting to standing plus that induced by sitting static handgrip (i.e. additive reflexes) was significantly less than the forearm vascular resistance response to the standing static handgrip (i.e. combined relexes), indicating a facilitatory interaction between exercise and orthostatic stimuli in hypertensives. In contrast, the algebraic sum of the heart rate responses to postural change from sitting to standing plus that induced by sitting static handgrip was significantly greater than the response to standing static handgrip, indicating an inhibitory interaction. CONCLUSIONS: In hypertensive patients, physiological orthostasis causes an increased vasoconstrictor response to static exercise, but this is opposed by an inhibitory influence on the heart rate response, with the result that the pressor response to static exercise is unaffected by upright posture.

Effects of isokinetic, isotonic and isometric submaximal exercise on heart rate and blood pressure.

The purpose of the present study was to compare arterial pressure (AP) and heart rate (HR) responses to submaximal isokinetic, isotonic and isometric exercises currently employed in physical rehabilitation therapy in terms of both magnitude and time-course. To this aim AP and HR were continuously and noninvasively measured in ten healthy subjects performing isokinetic, isotonic and isometric exercises at the same relative intensity. Isokinetic and isotonic exercises consisted of 30 knee extension/flexion repetitions at 40% of maximal effort. Isokinetic speed was set at 180 degrees s(-1). Isometric exercise consisted of a 60-s knee extension at 40% maximal voluntary contraction. The AP showed a rapid and marked increase from the onset of all types of exercise progressing throughout the exercises. Peak systolic (SAP) and diastolic (DAP) arterial pressure were 190.7 (SEM 8.9) and 121.6 (SEM 7.8) mmHg during isokinetic and 197.6 (SEM 11.2) and 128.3 (SEM 7.7) mmHg during isotonic exercise, respectively. During isometric exercise peak SAP and DAP were 168.1 (SEM 6.3) and 102.1 (SEM 3.7) mmHg, respectively [both lower compared to isokinetic and isotonic exercise (P < 0.05)]. The HR rose abruptly and after five isokinetic and isotonic repetitions it had already increased by about 30 beats min(-1), continuing to rise throughout the exercises. The HR response to isometric exercise was significantly less (P < 0.05) at all times. An immediate fall in AP, undershooting resting levels, was observed at the cessation of all types of exercise, being more marked after isokinetic and isotonic exercise. These results indicate that submaximal exercise of a dynamic type induces greater AP responses than intensity-matched isometric exercise and that even submaximal endurance-type rehabilitation exercise yields an elevated functional stress on the cardiovascular system which could precipitate hazardous events particularly in subjects with unrecognized cardiac diseases.

Evaluation of reproducibility of spontaneous baroreflex sensitivity at rest and during laboratory tests.

OBJECTIVE: The aim of the present study was to examine the reproducibility of arterial baroreflex sensitivity (BRS) provided by the spontaneous baroreflex method at rest and during laboratory tests. METHODS: Twenty healthy volunteers were studied 24 h apart, in the same laboratory and under the same environmental conditions, at rest, during active standing, while performing mental arithmetics and during static hand-gripping. Systolic blood pressure, mean arterial pressure and pulse interval were continuously and non-invasively measured by using a Finapres device. BRS was evaluated by analysing the slopes of spontaneously occurring sequences of three or more consecutive beats in which systolic blood pressure and pulse interval of the following beat both increased or decreased, in the same direction, in a linear fashion. Individual BRS were obtained by averaging all slopes computed within a given test. RESULTS: Under each test condition BRS did not differ significantly between the two consecutive days, showing strikingly similar values. The mean group coefficients of variation (CVAR), obtained by averaging individual CVAR, between the two experimental days were 15.0, 13.9 and 19.7% for resting, standing, static hand-gripping and mental arithmetic, respectively. No relationships were found between individual CVAR and individual mean arterial pressure, pulse interval and number of baroreflex sequences under any tested condition, on both experimental days. CONCLUSIONS: These results show that the spontaneous baroreflex method provides good BRS reproducibility under various stimuli that affect the neural control of circulation differently. They also suggest that BRS variability is dependent neither on haemodynamic modifications nor on the degree of baroreflex engagement, but it seems to reflect an inherent feature of the way in which arterial baroreflex modulate the heart period.

Adaptational changes in the neural control of cardiorespiratory function in a confined environment: the CNEC#3 experiment.

The goal of the study was to characterize the changes in neurovegetative control of the circulation, attending the presumed physiological and psychological stress originated by the isolation and confinement typical of the living condition of space stations, as simulated in a ground based unit, using time and frequency domain analysis. As a secondary goal we sought to verify the implementation of real time data acquisition, for off line spectral analysis of R-R interval, systolic arterial pressure (by Finapres) and respiration (by PVF2 piezoelectric sensors). We addressed the cardiorespiratory and neurovegetative responses to standardized, simple stressors (active standing, dynamic and static handgrip) on the EXEMSI 92 crew, before, during and after the isolation period. On average the appropriate excitatory responses (to stand, dynamic and static handgrip) were elicited also in isolation and confinement. Active standing and small masses muscular exercises are easy to be performed in a confined and isolated environment and provide a valuable tool for investigating the adaptational changes in neural control mechanisms. The possibility there exists of using this time and frequency domain approach to monitor the level of performance and well being of the space crew in (quasi) real time.

Evaluation of spontaneous baroreflex modulation of sinus node during isometric exercise in healthy humans.

The purpose of this study was to 1) evaluate the baroreflex (BR) modulation of the sinus node during isometric exercise in humans by analyzing the variations in pulse interval (PI) in response to beat-by-beat spontaneous changes in systolic arterial pressure (SAP), thus avoiding external intervention to alter arterial pressure (AP); and to 2) evaluate the specific influence of muscle chemoreflex on the SAP-PI relationship. Sixteen healthy males were studied during rest, handgrip at 30% of maximum voluntary contraction [isometric handgrip (IHG)], post-IHG arrested forearm circulation (AFC), and recovery. AP and PI were measured continuously and noninvasively. A BR response was defined by series of at least three consecutive beats in which SAP and PI of the following beat either increased or decreased in a linear fashion. In nine subjects, forearm (FVR) and calf vascular resistances (CVR) were determined. Mean slope (by linear regression) of SAP-PI sequences did not significantly differ between rest, IHG, and AFC (14.1 +/- 2.0, 12.2 +/- 1.6, and 13.2 +/- 1.4 ms/mmHg, respectively), i.e., BR sensitivity was unchanged. IHG resulted in a rightward shift of the regression line relating SAP to PI. The shift was maintained during AFC, when PI returned to control and AP fell slightly but remained significantly elevated. CVR, which did not change during IHG, significantly increased during AFC, whereas FVR increased during both IHG and AFC, but not significantly. The data indicate that arterial BR is "reset" to a higher operating point during isometric exercise. Muscle chemoreflex appears to be partially involved in this modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological unloading of cardiopulmonary mechanoreceptors by posture change does not influence the pressor response to isometric exercise in healthy humans.

In recent studies in humans the role of cardiopulmonary baroreflexes in modulating the cardiovascular responses to isometric exercise (somatic pressor reflex) has been investigated by performing static handgrip exercise during deactivation of cardiopulmonary receptors produced by low levels of lower body negative pressure; however, findings from these studies have not been consistent. The purpose of this study was to investigate whether a more physiological unloading stimulus of cardiopulmonary baroreceptors, obtained by sequentially changing posture, could influence the pressor response to somatic afferent stimulation induced by isometric exercise. To accomplish this, ten healthy subjects performed a 2-min isometric handgrip (IHG) at 30% maximal voluntary contraction after 10 min of supine rest and, in rapid sequence, after 10 min of sitting and 10 min of standing, at the time when, owing to their transitory nature, the cardiovascular effects, due to arterial baroreceptor intervention should have been minimal. During IHG arterial pressure (BPa) was continuously and noninvasively measured to quantify accurately the blood pressure response to IHG both in magnitude and time course. Results showed that the pressor response to IHG was not significantly influenced by change in posture, either in magnitude or in time course. The mean arterial pressure increased by 17.4 (SEM 2.5), 18.6 (SEM 1.2) and 17.0 (SEM 1.3) mmHg in supine, sitting and standing [2.3 (SEM 0.3), 2.5 (SEM 0.2) and 2.3 (SEM 0.2) kPa] positions, respectively. Also the heart rate response to IHG was unaffected by change in posture.(ABSTRACT TRUNCATED AT 250 WORDS)

[The physiopathological aspects and new therapeutic approaches in cardiac-circulatory failure]. / Aspetti fisiopatologici e nuovi indirizzi terapeutici nell'insufficienza cardio-circolatoria.

Pathophysiological mechanisms are reviewed concerning the onset and the perpetuation of the clinical features of congestive heart failure. This syndrome is a severe condition of poor prognosis and bad life quality which in the last decades has reached, in the western industrial countries, the highest levels of general mortality, mainly due to the high prevalence of hypertensive and ischaemic myocardiopathies in the last years. To the clinical features of heart failure mainly contributes a deregulation of the physiological compensatory mechanisms contemporarily and concurrently activated following the primary deficiency of the heart pump function. In physiological conditions, following the myogenic adapting mechanisms reflex mechanisms intervene, activated by intracardiac and aortic and carotid-sinus mechanoreceptors following the variations in intracardiac and intravascular pressure and generally evoking negative feed-back effects. In patients with heart failure arterial high pressure mechanoreceptors respond to the reduction in effective arterial pressure thus provoking a deactivation of the tonic inhibition on the sympathetic cardiovascular drive. This leads to an activation of peripheral and renal vasoconstrictor tone, to a raised medullary catecholamine incretion, to heart rate and inotropism stimulation, and to an increase in pituitary gland ADH production as well as to an activation of renin-angiotensin-aldosterone system (RAAS). Analogous vasoconstrictive, and sodium and water retentive effects can be elicited by endothelin produced by endothelial cells and found in high plasma levels in CHF. These excitatory effects, leading to a rise in systemic vascular resistance and to hydro-electrolytic retention with volume expansion, are not efficiently counteracted by the opposite effects triggered by cardiopulmonary vagally mediated mechanoreceptors activated by the raised cardiac filling pressure and leading to sympathetic nervous inhibition, peripheral and renal vasodilation, ADH and RAAS inhibition. Analogous effects should be provoked by the raised production, due to enhanced heart wall distension, of atrial natriuretic factor leading to vasodilation, natriuresis and diuresis. Reduced sensitivity of cardiopulmonary baroreceptors and lowered production of ANF due to structural cardiac changes could represent, according to most opinions, the main factors responsible for the prevailing sympathetic activation and hydro-saline retention in CHF. The activation of cardiopulmonary sympathetic positive-feed back afferents, could be also involved in the characteristic alteration of the vago-sympathetic balance in heart failure. The persistent reduction in heart pump function could lead to the instauration of vicious circles among the various regulatory systems and create an overcompensation condition.(ABSTRACT TRUNCATED AT 400 WORDS)