The effect of joint-compressive load and quadriceps muscle force on knee motion in the intact and anterior cruciate ligament-sectioned knee

To determine the effect of an externally applied joint-compressive load and a quadriceps muscle force on knee motion, we tested nine intact cadaveric knees and four knees after sectioning of the anterior cruciate ligament. Anteroposterior translation was measured at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 90 degrees of knee flexion after the application of an anteroposterior force of 100 N, a joint-compressive load of 0, 111, 222, 333, or 444 N, and a quadriceps force of 0 or 133 N. Both a joint-compressive load and a quadriceps force significantly decreased total anteroposterior translation by as much as 50% to 66% in intact knees and 42% to 71% in anterior cruciate ligament-sectioned knees. A substantial anterior translation was also found with the application of a joint-compressive load or a quadriceps force and no anterior force. We termed this translation an anterior neutral-position shift. The anterior neutral-position shift was significantly greater in the ligament-sectioned knees compared with the intact knees, so much so that at flexion angles greater than 15 degrees, the application of a 100-N posterior force could not translate the tibia to the most anterior position achieved in the intact knee with a 100-N anterior force.

[Changes in TXB2/6-keto-PGF1 alpha ratio and their relation to blood lipids of Type A behavioral patterns]

To study the pathophysiological relation between Type A behavioral pattern and coronary artery disease, we analyzed the Type A behavioral pattern, serum triglycerides (TG), cholesterol (TC), high density lipoprotein cholesterol (HDLc), and TXB2, 6-keto-PGF1 alpha in 60 patients with coronary artery disease and 60 age-sex-matched healthy subjects. All of them had normal blood pressure. The results showed Type A behavioral pattern was more prevalent than Type B behavioral pattern in coronary artery diseased patients and the reverse was true in the controlled subjects (P < 0.025); TG, TC and TXB2/6-keto-PGF1 alpha ratio increased significantly in Type A behavioral pattern compared with Type B behavioral patients, but HDLc/(TC+TG) and the level of HDLc decreased significantly in the Type A behavioral pattern than in the Type B behavioral pattern (P < 0.05). The TG, TC increased significantly and 6-keto-PGF1 alpha HDLc decreased significantly in the coronary artery diseased patients (P < 0.05). However, the ratio of TXB2/6-keto-PGF1 alpha was inversely related to HDLc/(TC+TG) among the coronary artery diseased patients. The results of this cross-sectional study suggest that coronary artery disease is associated with Type A behavioral pattern through the metabolism of lipids and prostaglandins in various ways.

The hypoxic moderation of systemic hypertension in spontaneously hypertensive rats

The mechanism of hypoxic moderation of systemic systolic blood pressure was investigated in spontaneously hypertensive rats (SHR). Male SHR rats were divided into hypoxic (H, 5000 m for 15 d) and normoxic (N) groups. The systemic blood pressure of SHR-H (24.9 +/- 1.2 kPa) was found to be 3 kPa lower than that in SHR-N (27.0 +/- 1.3 kPa) (P < 0.05). This protective effect may have been related to the adaptive changes in vascular reactivity which manifested as an increase in the relaxation response of the aorta to ACh (P < 0.01) and a drop in its contraction in response to 5-HT (P < 0.05) following hypoxic exposure. The hypoxic moderating effect against the development of systemic hypertension may have also been related to the increased plasma levels of ANP observed.

PECAM-1 is required for transendothelial migration of leukocytes

Platelet/endothelial cell adhesion molecule 1 (PECAM-1; CD31) is crucial to the process of leukocyte transmigration through intercellular junctions of vascular endothelial cells. A monoclonal antibody to PECAM, or recombinant soluble PECAM, blocks transendothelial migration of monocytes by 70-90%. Pretreating either the monocytes or the endothelial junctions with antibody blocks transmigration. If the endothelium is first activated by cytokines, anti-PECAM antibody or soluble recombinant PECAM again block transmigration of both monocytes and neutrophils. Anti-PECAM does not block chemotaxis of either cell type. Light and electron microscopy reveal that leukocytes blocked in transmigration remain tightly bound to the apical surface of the endothelial cell, precisely over the intercellular junction. Thus, the process of leukocyte emigration can be dissected into three successive stages: rolling, mediated by the selectin class of adhesion molecules; tight adhesion, mediated by the leukocyte integrins and their endothelial cell counter-receptors; and now transmigration, which, based on these studies, requires PECAM-1.

Nitric oxide mediates renal vasodilation during erythropoietin-induced polycythemia

The renal blood flow (RBF) of patients with polycythemia rubra vera is increased despite the high hematocrit (Hct) which elevates the whole blood viscosity. Since blood viscosity determines the shear force on the endothelium which is a major stimulus to nitric oxide (NO) release, we investigated the hypothesis that renal vasodilation during erythropoietin-induced erythrocytosis is mediated by the L-arginine-NO pathway. Groups of Sprague-Dawley rats received thrice weekly injections of erythropoietin (E) for two to five weeks; responses were contrasted with normal rats (N) which received sham injections. The first group was studied after five weeks of erythropoietin injections which led to sharp increases in Hct (E: 72 +/- 3 vs. N: 44 +/- 1%) and mean arterial pressure (MAP: 126 +/- 3 vs. 107 +/- 3 mm Hg). These rats had an elevated basal RBF whether measured by the clearance and renal extraction of PAH or by a transit-time renal blood flow meter. Subsequent groups were studied after two to three weeks of erythropoietin which raised the Hct more modestly to 59 +/- 2%. In this group, the basal MAP was similar in E and N rats. Graded doses of the NO synthase inhibitor, N omega-monomethyl-L-arginine (L-NMA) led to a steeper rise in MAP in E than N; at the highest doses, the MAP had increased by 36 +/- 2 in E and 23 +/- 3 mm Hg in N (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of atherosclerosis in arterial junctions. Modeling the release rate of low density lipoprotein and its breakdown products accumulated in blood vessel walls

Arterial bifurcations and surgically created junctions at anastomoses are places where blood flow may be disturbed and slow recirculation may occur. To address the hypothesis that such disturbances in flow may result in atherogenesis, the transfer of atherogenic substances from vessel wall to flowing blood was studied theoretically using a two dimensional T-junction model. Calculations showed that the transfer of atherogenic substances from vessel wall into flowing blood was suppressed in the two regions of disturbed flow, one in the main vessel, the other in the subsidiary vessel. The lowest release rates were at the points of flow separation and were found to be much lower than those in the undisturbed flow regions. Therefore, our mathematical model predicts that locally disturbed blood flows at arterial bifurcations and surgically created junctions are responsible for two distinct phenomena. First, they provide favorable conditions for the accumulation of LDL at the luminal surface, thus increasing the potential for lipid infiltration into the vessel wall, and second, they impair the transfer into blood of atherogenic substances accumulated in the vessel wall. Such mass transfer abnormalities may account for atherogenesis and late failures of arterial grafts at these sites.

Superoinferior translation in the intact and vented glenohumeral joint

The purpose of this investigation was to measure inferior translation in the intact and vented shoulder in different positions of abduction and rotation. Fifteen shoulders from adult cadavers were tested before and after venting of the joint capsule on an apparatus that permitted unconstrained translation when a 50 N inferior force was applied to the humeral shaft. The greatest inferior translation in the intact shoulder occurred at 45° abduction in neutral rotation. Venting the capsule significantly increased inferior translation in all positions but 45° abduction, and the greatest effect was seen at 0° glenohumeral abduction in neutral rotation. The so-called "sulcus sign" is the result of intraarficular vacuum effect and capsular laxity. Venting the capsule results in a significant increase in inferior translation. This is an important effect to consider during procedures for repairing instability of the shoulder, because failure to appreciate the normal "play" in inferior glenohumeral translation might lead the surgeon to believe that perceived laxity represents actual instability.

Transient picosecond response of the photorefractive effect in InP:Fe

The time lag of the crossed-polarized part of the transmitted probe pulse, which is due to photorefractive energy transfer from the pump pulse, is measured with respect to the original transmitted probe pulse. The average photorefractive response time of the crystal is estimated through theoretical analysis.

[Observation of efficacy of different dialytic therapies in renal transplantation preparation]

Fifty-seven cadaveric renal transplantations in fifty-five cases were analysed of them, thirty cases were prepared by continuous ambulatory peritoneal dialysis (CAPD group); twenty-seven transplantations in twenty-five cases were prepared by hemodialysis (HD group). Our data show that there is no significant difference in the survival duration between CAPD group and HD group; that there is also no significant difference in the survival duration between the two groups treated with the same immunosuppressive drugs, and that patients prepared by CAPD have a low risk of peritonitis after transplantation. It is better not to remove the Tenckhoff catheter until the graft function is stable so that it can be used for the transient peritoneal dialysis in the case of the insult of graft function or for the sampling of the peritoneal effusion for diagnosis of suspectable peritonitis after renal transplantation.

[Inhibitory effect of yunfujing on vestibular stimulative response in rats and volunteers]

Fifty female rats were used in the experiment. With rotation model, Yunfujing was shown to inhibit nystagmic response of rats. The inhibitory effect was 20-30 times stronger than that of Mihuanjun. In Coriolis test, the tolerance time of vestibular stimulative response was taken as a parameter for judging drug efficacy in 32 male volunteers. Following oral administration of Yunfujing at a dose of 400 mg, the tolerance time of vestibular stimulative response was prolonged significantly from 411.34 to 759.63 s. In the mean time, no changes of blood pressure and pulse were observed in the treated group.

[Experimental study of hypoxic pulmonary hypertension]

The dynamic changes in pulmonary vascular tone and reactivity of rats exposed to chronic hypobaric hypoxia were studied with cardiac catheterization and on perfusing isolated lung-preparations. It was found that their greatest rising appeared earlier than that of the pulmonary arterial pressure, and improving heart function might delay the development of hypoxic pulmonary hypertension. Whenever hypoxia was slight in extent, a compensatory increase in cardiac function was seen on the right side with no change in left heart. When hypoxia became more severe, an impairment of heart function occurred predominantly on the left side with or without decrease in the function of the right heart.

Uniform illumination of large targets using a lens array

Inserting an array of nearly 100 similar lenses into a common focal system, the uniformity of the illumination of a target can evidently be improved without being affected by the near-field distribution of laser beams. We report here geometrical- and physical-optics analyses of the lens array and compare them with the experimental results.