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Regional distribution of lung perfusion and ventilation at rest and during steady-state exercise after unilateral lung transplantation.

Cardiopulmonary exercise testing has previously demonstrated a reduced maximum oxygen uptake and anaerobic threshold, as well as abnormal wasted ventilation fraction and gas exchange after unilateral lung transplantation. To further explain the mechanisms of these abnormalities, we assessed the regional distribution of pulmonary blood flow and ventilation at rest and during steady-state exercise in nine recipients of unilateral lung transplants. Krypton-81 (81mKr) aerosol and technetium-99m (99mTc) were utilized to assess lung ventilation (V) and perfusion (Q), respectively. The digitalized images were trisected to analyze apical, mid-, and basilar lung perfusion and ventilation in both the transplanted and native lung, both at rest and steady-state upright exercise. Results were compared with previously reported data obtained in normal subjects in our laboratory using the identical technique. At rest, 75 +/- 13 percent of perfusion was directed to the transplanted lung; however, the corresponding fractional ventilation was only 67 +/- 14 percent. During exercise, there was no significant change in fractional perfusion or ventilation. Resting apical perfusion in the transplanted lung was higher than normal in four patients and comparable to normal in five patients. In contrast to the augmentation of apical perfusion observed in normal subjects during upright exercise, none of our patients increased the regional perfusion to the apices during exercise in either transplanted or native lungs. These unexpected responses suggest either more maximal allograft apical recruitment at rest due to the increased allograft perfusion or an abnormality in the apical pulmonary vasculature after transplantation. Furthermore, the relative mismatch in ventilation and perfusion in transplanted and native lungs suggests regions of high V/Q in the native, and low V/Q in the transplanted lung. This mismatch is most pronounced in recipients of single lung transplants for pulmonary vascular disease.

Adult↗

Hemodynamic effects of aerosolized iloprost in pulmonary hypertension at rest and during exercise.

STUDY OBJECTIVES: Aerosolized iloprost, a stable prostacyclin analog, improves functional capacity even in patients with pulmonary hypertension who did not show a vigorous hemodynamic response after iloprost inhalation at rest. We therefore speculated that aerosolized iloprost elicits more beneficial effects on pulmonary hemodynamics during exercise than at rest. DESIGN AND SETTING: A prospective, open, uncontrolled study at a university hospital. PATIENTS: Sixteen patients with primary or secondary pulmonary hypertension. INTERVENTIONS: Right-heart catheterization at rest and during exercise before and after the inhalation iloprost, 14 to 28 microg. RESULTS: Before iloprost treatment, exercise increased mean (+/- SD) pulmonary artery pressure (PAPm) from 45 +/- 8 to 70 +/- 13 mm Hg, cardiac output from 3.7 +/- 1.0 to 5.8 +/- 2.4 L/min, and pulmonary vascular resistance (PVR) from 904 +/- 322 to 1,013 +/- 432 dyne.s.cm(-5) (each p < 0.05). After recovery, iloprost reduced PAPm from 44 +/- 8 to 41 +/- 6 mm Hg, increased cardiac output from 3.7 +/- 1.0 to 4.9 +/- 1.4 L/min, and lowered PVR from 902 +/- 350 to 636 +/- 248 dyne x s x cm(-5) (each p < 0.05). During exercise after iloprost, PAPm increased to 57 +/- 8 mm Hg, cardiac output to 7.0 +/- 3.0 L/min, and PVR to 673 +/- 279 dyne x s x cm(-5) (each p < 0.05 vs first exercise test). Systemic BP was not altered significantly by iloprost treatment during exercise. CONCLUSIONS: Aerosolized iloprost treatment exerts more favorable effects on pulmonary hemodynamics during exercise than at rest. These findings explain the functional improvement observed in patients with pulmonary hypertension who show only a moderate pulmonary vasodilatory response during iloprost inhalation at rest. Whether these beneficial effects have prognostic significance needs to be elucidated by further study.

Administration, Inhalation↗

Bed rest or ambulation in the initial treatment of patients with acute deep vein thrombosis or pulmonary embolism: findings from the RIETE registry.

BACKGROUND: Traditionally, many patients with acute deep vein thrombosis (DVT) are treated not only by anticoagulation therapy but additionally by strict bed rest, which is aimed at reducing the risk of pulmonary embolism (PE) events. However, this risk has not been subjected to empirical verification. PATIENTS AND METHODS: The Registro Informatizado de la Enfermedad TromboEmbólica is a Spanish registry of consecutively enrolled patients with objectively confirmed, symptomatic acute DVT or PE. In this analysis, the clinical characteristics, details of anticoagulant therapy, and clinical outcomes of enrolled patients with and without strict bed rest prescribed during the first 15 days were compared. Patients in whom ambulation was not possible were not included in this analysis. RESULTS: A total of 2,650 patients entered the study (DVT, 2,038 patients; PE, 612 patients). Of these patients, 1,050 DVT patients (52%) and 385 PE patients (63%) were prescribed strict bed rest. New events of symptomatic, objectively confirmed PE developed during the 15-day study period in 11 patients with DVT (0.5%) and 4 patients with PE (0.7%). Five of these 15 patients (33%) died as a result of their PE. Age < 65 years (odds ratio [OR], 3.1; 95% confidence interval [CI], 0.98 to 11) and cancer (OR, 3.0; 95% CI, 0.98 to 9.1) were associated with an increased rate of new PEs. There were not significant differences between bedridden and ambulant patients in terms of new PE events, fatal PE, or bleeding complications. CONCLUSIONS: Our findings confirm those from previous reports suggesting that bed rest has no influence on the risk of developing PE among patients with acute DVT of the lower limbs. In addition, our findings show for the first time the lack of influence of bed rest even in patients presenting with acute submassive PE.

Bed Rest↗

Conservation of oxygen supply using a reservoir nasal cannula in hypoxemic patients at rest and during exercise.

A reservoir nasal cannula which stores oxygen during exhalation and delivers it as a bolus during inhalation has been reported to conserve oxygen delivery in patients with chronic obstructive pulmonary disease (COPD) at rest. We compared the effects upon arterial oxygen saturation (SaO2) of the reservoir cannula and a standard nasal cannula in hypoxemic obstructed and restricted patients at rest and during exercise. The SaO2 was monitored by ear oximeter. While at rest, 13 obstructed and four restricted patients breathed oxygen from the reservoir cannula at 0.5, 1.0, 1.5, and 2.0 L/min and from a standard cannula at 0.5, 1.0, 2.0, 3.0, and 4.0 L/min. Mean SaO2 was significantly higher with the reservoir cannula compared to the standard cannula at 1.0 and 2.0 L/min (p less than 0.0006) and tended to be higher at 0.5 L/min (p less than 0.1). Seven obstructed patients walked on a level treadmill at 0.75 mph while breathing oxygen at 0.5 and 1.5 L/min from the reservoir cannula and at 1.0 and 3.0 L/min from the standard cannula. The SaO2 during exercise with the reservoir cannula was comparable to that with the standard cannula at approximately half of the oxygen flow rate. The ratio of the oxygen flow rate of the standard to the reservoir cannula to produce 90 percent saturation was estimated and found to be 2.5 +/- 0.8 (mean +/- SD) for patients at rest and 2.9 +/- 1.8 during exercise. We conclude that in hypoxemic patients at rest and during exercise, the reservoir cannula uses less than half the oxygen of a standard cannula to produce similar improvement in SaO2 and thus has advantages of a reduced cost of ambulatory therapy with low-flow oxygen and a longer time permitted away from a stationary source of oxygen.

Carbon Dioxide↗

Electrolyte changes in plasma and urine of athletes during acute and rigorous bed rest and ambulatory conditions.

Rigorous bed rest (RBR) induces significant electrolyte changes, but little it is not known about the effect of acute bed rest (ABR) (i.e., abrupt confinement to a RBR). The aim of this study was to measure urinary and plasma electrolyte changes during ABR and RBR conditions. The studies were done during 3 d of a pre-bed-rest (BR) period and during 7 d of an ABR and RBR period. Thirty male trained athletes aged, 24.4 +/- 6.6 yr were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), acute-bed-rested subjects (ABRS), and rigorous-bed-rested subjects (RBRS). The UACS group experienced no changes in professional training and daily activities. The ABRS were submitted abruptly to a RBR regimen and without having any prior knowledge of the exact date and time when they would be subjected to an RBR regimen. The RBRS were subjected to an RBR regime on a predetermined date and time known to them from the beginning of the study. Sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and phosphate (P) in plasma and urine, plasma renin activity (PRA) and plasma aldosterone (PA), physical characteristics, peak oxygen uptake, and food and water intakes were measured. Urinary Na, K, Ca, Mg, and P excretion and plasma Na, K, Mg, Ca, and P concentration, PRA, and PA concentration increased significantly (p < or = 0.01), whereas body weight, peak oxygen uptake, and food and water intakes decreased significantly in the ABRS and RBRS groups when compared with the UACS group. However, urinary and plasma Na, K, Mg, P, and Ca, PRA, and PA values increased much faster and were much greater in the ABRS group than in the RBRS group. Plasma and urinary Na, K, Ca, Mg, and P, PRA and PA levels, food and water intakes, body weight, and peak oxygen uptake did not change significantly in the UACS group when compared with its baseline control values. It was shown that RBR and ABR conditions induce significant increases in urinary and plasma electrolytes; however, urinary and plasma electrolyte changes appeared much faster and were much greater in the ABRS group than the RBRS group. It was concluded that the more abruptly motor activity is ended, the faster and the greater the urinary and plasma electrolyte change.

Adult↗

The effects of rest interval length on ratings of perceived exertion during dynamic knee extension exercise.

The objective of this study was to examine the effects of rest interval length on perceived exertion and during 3 sets of 10 inertial knee extension repetitions. Thirty healthy men (n = 15) and women (n = 15) volunteers were randomly assigned to 1 of 3 groups (1-, 2-, or 3-minute rest interval length) following the establishment of each subject's 1 repetition maximum (1RM) for inertial knee extension exercise. Subjects in each group performed 3 sets of 10 repetitions at 70% of a theoretical 10RM (based on each subject's 1RM), with a 1-, 2-, or 3-minute rest interval between each set. Perceived exertion was recorded, via the Borg category-ratio scale, from each subject after each repetition of each set. The results demonstrated no significant rest interval length effect on perceived exertion across the 3 sets of 10 repetitions. The results revealed a significantly higher perceived exertion value following the first repetition in set 3 as compared to sets 2 and 1 in all groups. The increase in perceived exertion within each set, as described by the slope, was found to be significantly lowest in set 1, as compared to sets 2 and 3. The major findings of this study demonstrate that perceived exertion significantly increases in a similar manner across 3 sets of 10 knee extension repetitions, despite rest interval lengths of 1-3 minutes.

Adult↗

The optimal complex training rest interval for athletes from anaerobic sports.

Complex training research has indicated that 3-4 minutes may be an optimum intracomplex rest interval. The purpose of this study was to determine if a heavy resistive exercise causes performance enhancement of a slow stretch-shortening cycle exercise and if there is an optimal rest interval. Eighteen subjects performed countermovement jumps (CMJs) before and after a 5 repetition maximum back squat lifting protocol. This procedure was repeated 4 times over 2 days using rest intervals of 30 seconds and 2, 4, and 6 minutes. Flight time and peak ground reaction force (GRF) were the dependent variables. All jumps were performed on a specially constructed sledge and force platform apparatus. Repeated measures analysis of variance found a significant reduction in flight time at the 30-second and 6-minute interval (p < 0.05). No significant difference was found between men and women. Only the men showed an enhancement in jump performance after the 4-minute interval. The improvement window was different for each subject, and an analysis of the greatest increase and decrease in flight time and peak GRF was conducted, showing a significant decrease for men and women and a significant increase in flight time for men and peak ground reaction force for women. The results suggest that complex training can benefit or inhibit CMJ performance depending on the rest interval. The individual determination of the intracomplex rest interval may be necessary in the practical setting.

Adult↗

Rest-interval length affects leukocyte levels during heavy resistance exercise.

We sought to determine the effect of varying rest intervals on leukocyte levels during heavy resistance exercise. Nine college men completed 2 exercise bouts of 10 sets of 10 repetitions at 65% 1 repetition maximum (1RM) leg press with 1- (1MIN) or 3-minute (3MIN) rest intervals, respectively. Blood collected at rest (PRE), immediately postexercise (POST), and 1.5 hours postexercise (1.5H) was analyzed for leukocyte levels. Data were analyzed using a 2 x 3 repeated measures analysis of variance. A greater PRE-POST lymphocytosis (+83% vs. +16%, p = 0.002) and monocytosis (+47% vs. +15%, p = 0.005) was observed following 1MIN vs. 3MIN. Serum creatine kinase (CK) activity was increased to a greater extent 24 h postexercise following the 1-minute rest protocol (p = 0.022). CK was correlated (r = 0.611) to the PRE-POST lymphocytosis. We conclude that short rest intervals increase the extent of postexercise lymphocytosis and monocytosis, when total work is kept constant.

Adult↗

Abnormalities of T waves in effort angina pectoris patients at rest evaluated by spatial velocity electrocardiogram.

The normal shape of the T wave on the standard 12-lead electrocardiogram (ECG) is asymmetrical. The spatial velocity electrocardiogram (SVECG) is a method of recording the slope of the wave of the ECG and makes it possible to quantify the symmetry of the ECG-T wave. The aim of this study was to diagnose resting effort angina pectoris not detectable by conventional resting ECG using SVECG. We studied SVECG-T waves in effort angina pectoris patients with significant coronary artery stenosis but with normal resting ECG (AP group: 50 subjects) and in an age- and sex-matched normal controls (N group: 30 subjects). The SVECG is depicted as a simple differential wave, and all SVECG-T waves had two peaks. The first peak of the SVECG-T wave was designated as the 'a' wave and the second peak as the 'c' wave. The heights (a wave-mag, c wave-mag) and c wave-mag/a wave-mag ratio (c/a ratio) were calculated. The c/a ratio was significantly decreased in the AP group (1.52 +/- 0.29 vs 1.87 +/- 0.27, p < 0.0001). In cases below the cut off c/a ratio of 1.7, the diagnostic sensitivity, specificity and accuracy for effort angina pectoris were retrospectively evaluated to be 82%, 70% and 78%, respectively. The heights of the 'a' and 'c' waves correspond to the maximum slope of the ascending and descending limbs of the T wave on ECG. The symmetrization of the T wave on ECG is considered to occur when the c/a ratio decreases and approaches 1.0. In conclusion, the c/a ratio of the SVECG-T wave is a useful index to diagnose effort angina pectoris at rest when the resting ECG is normal.

Aged↗

Treatment of high-altitude pulmonary edema by bed rest and supplemental oxygen.

STUDY OBJECTIVES: We evaluated the safety and efficacy of treating high-altitude pulmonary edema (HAPE) by bed rest and supplemental oxygen at moderate altitudes. We also characterized clinical parameters in HAPE before and after treatment. DESIGN: Case series. SETTING: Two primary care centers at about 9,200 feet (2,800 meters) above sea level. TYPE OF PARTICIPANTS: All patients aged 16-69 years who had been diagnosed with HAPE and were treated with bed rest and supplemental oxygen. Patients were seen on a follow-up visit. INTERVENTIONS: Selected patients were treated with bed rest and supplemental oxygen rather than hospital admission or descent. MAIN OUTCOME MEASURE: Patients were considered improved on follow-up if room air arterial oxygen saturation was increased by 10 percentage points or if their symptoms had improved. RESULTS: Of 58 patients with confirmed HAPE, 25 (43%) were treated by bed rest and supplemental oxygen and were seen on return visits to the clinic. All of the treated patients improved at the return visit. Systolic blood pressure, heart rate, respiratory rate, and temperature decreased significantly between the first visit and the return visit. Oxygen saturation improved between visits. CONCLUSION: Some patients with HAPE at moderate altitudes where medical facilities are available can be safely treated with bed rest and oxygen without descent.

Adolescent↗

Heart rate variability in athletes and nonathletes at rest and during head-up tilt.

The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV), differs during supine rest and head-up tilt (HUT) when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S) and 10 trained cyclists (C) were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70 masculine HUT. The major aerobic capacity of athletes was expressed by higher values of VO2 at anaerobic threshold and peak conditions (P < 0.05). At rest the athletes had lower heart rates (P < 0.05) and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians): 59.1 ms (S) vs 89.9 ms (C), P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians): 55.7 ms (S) vs 69.7 ms (C), P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups.

Adult↗

Loss of resting bradycardia with detraining is associated with intrinsic heart rate changes.

The mechanisms underlying the loss of resting bradycardia with detraining were studied in rats. The relative contribution of autonomic and non-autonomic mechanisms was studied in 26 male Wistar rats (180-220 g) randomly assigned to four groups: sedentary (S, N = 6), trained (T, N = 8), detrained for 1 week (D1, N = 6), and detrained for 2 weeks (D2, N = 6). T, D1 and D2 were treadmill trained 5 days/week for 60 min with a gradual increase towards 50% peak VO2. After the last training session, D1 and D2 were detrained for 1 and 2 weeks, respectively. The effect of the autonomic nervous system in causing training-induced resting bradycardia and in restoring heart rate (HR) to pre-exercise training level (PET) with detraining was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. T rats significantly increased peak VO2 by 15 or 23.5% when compared to PET and S rats, respectively. Detraining reduced peak VO2 in both D1 and D2 rats by 22% compared to T rats, indicating loss of aerobic capacity. Resting HR was significantly lower in T and D1 rats than in S rats (313 +/- 6.67 and 321 +/- 6.01 vs 342 +/- 12.2 bpm) and was associated with a significantly decreased intrinsic HR (368 +/- 6.1 and 362 +/- 7.3 vs 390 +/- 8 bpm). Two weeks of detraining reversed the resting HR near PET (335 +/- 6.01 bpm) due to an increased intrinsic HR in D2 rats compared with T and D1 rats (376 +/- 8.8 bpm). The present study provides the first evidence of intrinsic HR-mediated loss of resting bradycardia with detraining in rats.

Animals↗

Behavior of resting Aedes aegypti (Culicidae: Diptera) and its relation to ultra-low volume adulticide efficacy in Panama City, Panama.

The resting behavior of Aedes aegypti (L.) adults was investigated in 14 districts of Panama City, Panama, in relation to ground ultra-low volume (ULV) applications of malathion. Adults primarily rested inside the premises (75.1%) at a distance > 6 m from the street (86.4%). Both sexes rested mainly in bedrooms, living rooms, and bathrooms. The small ULV aerosol droplets (2-4 microns) penetrated all indoor resting sites of Ae. aegypti, but in low amounts. Because of the low amount of insecticide reaching the primary resting sites within the premises, limited control of the Ae. aegypti was obtained. This limited the potential effectiveness of ground vehicle ULV applied insecticide as a dengue epidemic control method.

Aedes↗

Circadian changes in urinary bicarbonate, nitric oxide metabolites and pH in female player during handball camp involved in an exercise, rest and sleep cycle.

Bicarbonate and nitric oxide levels are important humoral factors in the blood and are affected by the human body's physical condition. There are few reports, however, on changes in blood bicarbonate and nitric oxide levels during exercise and rest. Since urinary bicarbonate and nitric oxide metabolites reflect the levels of bicarbonate and nitric oxide in the blood, we studied circadian changes in 6 female athletes by monitoring their urinary pH and their levels of urinary bicarbonate and nitric oxide metabolites. Measurements were taken during exercise, rest and sleep. Six female athletes participated in a 3-day team handball training camp where they followed a schedule of exercise, rest and sleep. Urinary samples were collected immediately before and after handball training, at bed-time and upon waking. The urinary pH and levels of urinary bicarbonate and nitric oxide metabolites, including nitrite and nitrate, were examined with a blood gas analyzer and a NOx analyzer. The samples collected after handball training, as compared to the samples taken before exercise, showed a decreased pH, a decrease in levels of bicarbonate and little change in NO metabolites. During rest, urinary bicarbonate, NO metabolites and pH increased markedly in all 6 subjects. The levels of urinary bicarbonate, NO metabolites and pH significantly decreased upon waking. This study took into account the subjects' various physiological conditions when considering the significance of their changes in urinary bicarbonate, NO metabolites and pH during the 3 day handball training program. There were significant circadian changes in the urinary pH, and in the levels of urinary bicarbonate and nitric oxide metabolites, in the athletes involved in the exercise, rest and sleep program at team handball camp.

Activity Cycles↗

Effect of active rest by oral reading on a mirror-drawing task.

This study investigated the effect of active rest on perceptual-motor learning. Two groups received different techniques for promoting recovery during an 8-min. rest period between practice on a mirror-drawing task. The two techniques were active rest by reading orally a book unrelated to the experiment and passive rest during which the group sat without moving the body or thinking about the experiment. Significantly fewer number of errors in the mirror drawing occurred for those subjects who used oral reading during rest. The possibility of raising arousal was discussed.

Adolescent↗

Endogenous myelin basic protein is presented in the periphery by both dendritic cells and resting B cells with different functional consequences.

Multiple sclerosis is an inflammatory disease believed to be triggered by erroneous activation of self-reactive T cells specific for myelin proteins such as myelin basic protein (MBP). Inflammation is limited to the CNS, suggesting that the myelin-specific T cells encounter their Ags only after they cross the blood-brain barrier. However, our previous studies in mice showed that MBP epitopes are constitutively presented in lymphoid tissues. Here we identified which APCs in lymph nodes present endogenous MBP epitopes and determined the functional consequences of this presentation for both naive and activated MBP-specific T cells. Both CD8alpha+ and CD8alpha- dendritic cells were potent stimulators of proliferation for both naive and previously activated/memory MBP-specific T cells. Surprisingly, resting B cells also presented endogenous MBP that was acquired using a BCR-independent mechanism. Interaction with resting B cells triggered proliferation of both naive and activated MBP-specific T cells. Activated/memory MBP-specific T cells proliferating in response to resting B cells presenting endogenous MBP did not produce cytokines and became more refractory to subsequent stimulation. Interestingly, cytokine production by activated/memory T cells was triggered by resting B cells if the number of MBP epitopes presented was increased by adding exogenous MBP peptide. These results suggest that activated MBP-specific T cells may become less pathogenic in vivo following encounter with resting B cells presenting steady-state levels of endogenous MBP but can expand and remain pathogenic if the amount of MBP presented by B cells is increased, which could occur during chronic demyelinating disease.

Animals↗

Comparison of intra-articular injection of 2 ml of 0.9% NaCl solution with rest alone for treatment of horses with traumatic arthritis.

OBJECTIVE: To compare effects of intra-articular injection of 2 ml of 0.9% NaCl solution with rest alone for treatment of horses with traumatic arthritis. ANIMALS: 38 Standardbred horses with moderate to severe lameness that resulted from traumatic arthritis. PROCEDURE: Horses were stratified on the basis of number of affected joints. In each stratum, horses were allocated randomly to treatment groups (intraarticular injection of 2 ml of 0.9% NaCl solution vs rest only). Treatment was for a period of 3 weeks. Horses were inspected weekly with a final examination 2 to 4 weeks after completion of treatment. RESULTS: Mean lameness index was significantly lower during the 3-week treatment period and the entire study period for the NaCl-injected group. A significant decrease in the lameness index during the first 3-week treatment period also was detected for the rest-only group; however, the lameness index increased significantly for this group during the follow-up period, and an overall significant decrease was not detected. Comparison of the lameness index curve indicated a difference in favor of NaCl injection, with a significant difference between the 2 groups at final examination. Nine horses became sound during treatment with rest only, but 6 relapsed before final examination. In the NaCl-injected group, 5 of 10 sound horses relapsed. CONCLUSIONS AND CLINICAL RELEVANCE: Intra-articular injection of 2 ml of 0.9% NaCl solution was beneficial in horses with traumatic arthritis. Use of rest alone for a limited period was inadequate for treatment of young Standardbred horses with traumatic arthritis.

Animals↗

Altered patterns of regional cerebral blood flow in patients with Huntington's disease: a SPECT study during rest and cognitive or motor activation.

UNLABELLED: Previous research using functional transcranial Doppler sonography showed that blood flow velocity in the anterior cerebral artery is significantly less in patients with Huntington's disease (HD) than in healthy volunteers while they are completing mazes. The current research used SPECT to study regional cerebral blood flow (rCBF) in patients with HD during rest and maze testing. METHODS: Seven patients with HD and 9 healthy volunteers were injected twice with 0.96-1.15 GBq 99mTc-labeled hexamethylpropylene amine oxime. During the 10 min after injection, subjects either solved mazes or rested with their eyes open while looking at a modified maze. After SPECT, count density was obtained from 11 brain regions and corrected for decay and injected dose. Two types of data generated from this experiment, including absolute regional counts per pixel in the regions of interest and count density computed as a percentage of activity in the lateral cerebellum, were compared between groups. RESULTS: During rest, the absolute regional count density was greater in the HD brains than in the healthy brains (P < 0.001). Count density was typically between 8% and 13% higher in the HD group than in the healthy group. The single exception was the caudate density, for which the 2 groups had similar values. No significant differences in absolute regional count density were observed between groups during maze testing. When rCBF was calculated as a percentage of cerebellar rCBF, analysis of covariance found decreases in HD caudate density (P < 0.001) and orbital frontal cortex density (P < 0.005) during maze testing. Changes in rCBF in the caudate nucleus predicted gene status (P = 0.0007) and correlated with time to complete the mazes (P < 0.05). CONCLUSION: Patients with HD showed an increase in resting rCBF for all brain regions measured except the caudate nucleus. When rCBF was calculated as a percentage of cerebellar blood flow, rCBF in the striatum and orbital cortex in patients with HD was less during maze testing than during rest. Although the cause of these rCBF changes in HD patients is unclear, nitric oxide synthase, a regulator of vasomotor activity, may be involved.

Caudate Nucleus↗