Rigidity of circulating lymphocytes is primarily conferred by vimentin intermediate filaments.
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Lymphocytes need rigidity while in circulation, but must abruptly become deformable to undergo transmigration into tissue. Previously, the control of leukocyte deformability has been attributed to microfilaments or microtubules, but the present studies demonstrate the greater importance of vimentin intermediate filaments (IFs). In circulating T lymphocytes, IFs form a distinctive spherical cage that undergoes a rapid condensation into a juxtanuclear aggregate during chemokine-induced polarization. Measurements of the resistance of peripheral blood T lymphocytes to global deformation demonstrate that their rigidity is primarily dependent on intact vimentin filaments. Microtubules, in contrast, are not sufficient to maintain rigidity. Thus, vimentin IFs are a primary source of structural support in circulating human lymphocytes, and their regulated collapse is likely to be an essential element in chemokine-induced transendothelial migration. (+info)
Patient morbidity and some patterns of family practice in southeastern Ontario.
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Over a 7-month period the trial version of the International Classification of Health Problems in Primary Care (ICHPPC) was studied. Ten community physicians reported 28 399 encounters wtith 11 437 patients. The overall distribution of health problems was comparable to that found in other North American studies. Some differences between the morbidity distributions in urban and rural practices varies from those of previous Canadian studies. Other differences between practices appeared to be related to the interests and training of the individual physicians. The workload of the physicians varied considerably. Many of the encounters involved problems for which there may be minimal benefit from medical intervention, and there was a large discrepancy in the frequency of follow-up visits for specified stable chronic health problems. The implications of these interpractice variations in the altering field of health care are discussed. (+info)
Circulation Research: origin and early years.
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Circulation Research, first published in 1953, was created by the American Heart Association as "the authoritative new journal for investigators of the basic sciences as they apply to the heart and circulation." This review of the early years of the journal highlights the contributions of the first four Editors: Carl J. Wiggers, Carl F. Schmidt, Eugene M. Landis, and Julius H. Comroe, Jr. The success of Circulation Research is seen not only in the high quality of the articles published in its pages but also in the remarkable improvements in prevention and treatment of cardiovascular disease that have occurred over the past half century. (+info)
Surgical and physical stress increases circulating blood dendritic cell counts independently of monocyte counts.
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Dendritic cells (DCs) are specialized antigen-presenting cells that have the unique ability to initiate a primary immune response. The effect of physiologic stress on circulating blood DCs has thus far not been studied. In this study, we applied a recently developed method of counting blood DCs to test the hypothesis that significant stress to the body such as surgery and exercise might induce measurable changes in the DC numbers, subsets, phenotype, and function. Twenty-six patients scheduled for elective laparoscopic cholecystectomy, 4 for elective hysterectomy, 56 controls, and 5 volunteers who underwent a stress exercise test were enrolled in the study. Absolute DC counts increased acutely (71.7% +/- 11% [SEM], P =.0001) in response to the stress of surgery and dropped below preoperative levels (-25% +/- 14% [SEM], P =.05) on days 2-3. The perioperative DC subset balance remained constant. Interestingly, DC counts changed independently of monocyte counts. Exercise also induced a rise in DC counts but coincidentally with monocyte counts. Surprisingly, no phenotypic or functional activation of DCs was seen in either stress situations in vivo. DCs are rapidly mobilized into the circulation in response to surgical and exercise stress, which may serve to prepare the host's immune defenses against trauma. The independent regulation of the DC and monocyte counts reinforces the distinction between these 2 cell populations. (+info)
Noninvasive transcutaneous determination of access blood flow rate.
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BACKGROUND: Current indicator dilution techniques for determining the vascular access blood flow rate (Qa) require reversal of the dialysis blood lines and are time consuming. We have recently described an indicator dilution technique for determining Qa using a novel optical transcutaneous hematocrit (Hct) sensor that does not require reversal of the dialysis lines, and have validated the accuracy of this method (TQa) in vitro. METHODS: This study compared results using the TQa method with those obtained using a similar indicator dilution technique but which required reversal of the dialysis lines (HD01 Monitor, Transonic Systems, Ithaca, NY, USA) during routine hemodialysis in 59 patients (25 native fistulas and 34 synthetic grafts). The sensor for the TQa method was placed on the skin directly over the access to measure changes in Hct approximately 25 mm downstream of the venous needle. A single 30 mL bolus of saline was infused into the dialyzer venous line over approximately six seconds without reversal of the dialysis blood lines, and the vascular access flow rate was calculated using indicator dilution methods from the time-dependent decrease in the Hct downstream of the venous needle. Two additional small-scale studies were performed to assess the effect skin pigmentation and to evaluate further the reproducibility of the TQa method. RESULTS: Qa values determined by the TQa method were highly correlated with those determined by the HD01 method (N = 72, R2 = 0.948, P < 0.001) over the range of 153 to 2,042 mL/min. There was no significant difference between vascular access flow rates determined by the TQa method and those determined by the HD01 METHOD: Results from one small-scale study showed that the relationship between Qa values determined by the TQa and the HD01 methods was similar when tested only among black patients (N = 12), suggesting that skin pigmentation is not an important determinant of the accuracy of the TQa METHOD: The second small-scale study showed that the intratreatment coefficient of variation for the TQa method was 7.8 +/- 5.6% (N = 14). CONCLUSIONS: : These results show that transcutaneous measurement of Qa is an accurate, simple, and fast technique for determining Qa without requiring the reversal of the dialysis blood lines. (+info)
Effects of exposure to high temperature and feeding level on regional blood flow and oxidative capacity of tissues in piglets.
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To determine to what extent exposure to high ambient temperature and feeding level affect tissue energy metabolism in piglets, regional blood flow and oxidative capacity of tissues were evaluated in sixteen 21.8 +/- 2.8 kg pigs. At 5 weeks of age, littermates were divided into three groups and acclimated to the treatment for 25 days. One group was reared at 33 degrees C and fed ad libitum (33AL, n = 6) while the other two groups were maintained at 23 degrees C and either pair-fed on the basis of the food consumption of their 33AL littermates (23PF, n = 5), or fed ad libitum (23AL, n = 5). Regional blood flow was determined in conscious pigs by injection of coloured microspheres, which were recovered in different tissues after slaughter. Activities of cytochrome oxidase and cytochrome aa(3) content were measured in tissue homogenates of heart, longissimus dorsi and rhomboideus muscles, liver and small intestine. There was decreased blood flow to internal adipose tissue (42 %) and increased blood flow to peripheral tissues (skin, 44 %) and tissues implicated in respiratory evaporative heat loss (diaphragm, 45 %, lungs, 59 %) at 33 degrees C compared to 23 degrees C, which can be viewed as an effective mechanism for increasing heat loss at high temperature. In addition, the concomitant decrease in blood flow (49 %) and slight reduction of oxidative capacities in both muscles at 33 degrees C might contribute to the reduction in thermogenesis, but these effects were also observed when the feeding level was reduced at thermal neutrality (23PF group). In the viscera (intestine, liver), blood flow was decreased in the two groups on a restricted food intake (about 50 % of 23AL), independently of environmental temperature. The results suggest that most of the mechanisms associated with the reduction in energy expenditure during warm acclimation are related to the adaptive reduction in food intake. Experimental Physiology (2001) 86.1, 83-91. (+info)
Effects of angiotensin-(1-7) on forearm circulation in normotensive subjects and patients with essential hypertension.
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Previous animal studies have shown that angiotensin (Ang)-(1-7) is a biologically active component of the renin-angiotensin system, acting as a vasoactive agent, and may play a role in the blood pressure regulation. There is little information, however, on the effect of Ang-(1-7) on human circulation or the mechanism of its action. To investigate the effect of Ang-(1-7) on forearm circulation and to determine whether this effect is altered in patients with essential hypertension, we measured change in forearm blood flow using venous occlusion plethysmography in response to intra-arterial infusion of Ang-(1-7) (10(-10), 10(-9), and 10(-8) mol/min; for 5 minutes) in normotensive control subjects (n=8) and patients with essential hypertension (n=8). Infusion of Ang-(1-7) significantly increased the forearm blood flow response in a dose-dependent manner in both normotensive control subjects (28.7+/-9.7%, at 10(-8) mol/min; P<0.05) and hypertensive patients (31.8+/-15.2%, at 10(-8) mol/min; P<0.05). The vasodilatory effect of Ang-(1-7) was similar in the two groups. Intra-arterial infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthesis inhibitor, did not alter the forearm blood flow response to Ang-(1-7) in either group. These findings suggest that Ang-(1-7) causes vasodilation in forearm circulation of normotensive subjects and patients with essential hypertension through a pathway that is independent of nitric oxide synthesis. (+info)
Arterial occlusion after cannulation.
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The occurrence of ischaemic changes, arterial occlusion, and other complications which may follow percutaneous arterial cannulation was assessed in a survey of 155 patients. No patient complained of or had signs of ischaemic damage though signs of arterial occlusion were found in 33 patients (22%). These signs were significantly more common after periods of cannulation greater than six hours (43%) than after less than six hours cannulation (17%). During recovery from occlusion all patients had palpable pulsation over the artery even though blood flow seemed to be absent. By the end of follow-up blood flow had returned in 19 of the 33 occluded arteries. (+info)