Longitudinal forces acting at side-to-end and end-to-side anastomoses when a knitted polyester arterial prosthesis is implanted in the dog

In a previous study, which investigated the tensions at the proximal and distal end-to-end anastomoses of a vascular prosthesis, no significant differences were found in the longitudinal forces between the two anastomotic sites after different periods of implantation. The present follow-up study was devised to study the longitudinal forces at a proximal side-to-end and a distal end-to-side anastomosis using a warp knitted polyester prosthesis implanted as a canine thorocoabdominal bypass. The external surface of the prosthesis contained a specially printed "tension indicator" design, which enabled changes in length to be assessed photographically at the two anastomoses at the time of implantation and at sacrifice. The longitudinal force at each site was then calculated using a relationship obtained experimentally between the total longitudinal force and the changes in length of the virgin graft in vitro. The in vitro measurements on the prosthesis were performed using a computer-controlled laser calibration system. Although the results showed a tendency toward a gradual loss in longitudinal force at both anastomoses over 7 months in situ, statistical analysis showed no significant difference in the longitudinal force at the two anastomotic sites after any period of implantation. Histopathological and textile analysis also showed that the characteristics of the prostheses were similar at both anastomotic sites. This does not mean, however, that the intramural stress concentrations experienced by the two sites were the same. While comparing the level of the longitudinal forces measured in this study with those observed in the previous thoracic aorta study using end-to-end anastomoses, no significant differences were observed due to the different types of anastomoses. It would appear that the longitudinal force is not one of the main etiological factors that cause the formation and localization of anastomotic failure.

Strategies for an anterior capsular shift of the shoulder. A biomechanical comparison

We evaluated the effect of two different anterior capsular shift strategies on load-induced multidirectional glenohumeral motion. Nine cadaveric shoulders were tested on a special test apparatus in which three motions were constrained but which allowed simultaneous measurement of three translations: anteroposterior, mediolateral, and superoinferior. A simulated Bankart lesion was created by detaching the inferior glenohumeral ligament and labrum from the anterior glenoid from 5 mm superior to the anterior band of the inferior glenohumeral ligament to a point just posterior to the infraglenoid tubercle. The two types of medial-based anterior capsular shifts were performed sequentially using fixation via a transglenoid drill hole and No. 2 suture. One shift medialized the anterior capsule on the glenoid by 5 mm; the other one shifted the anterior capsule 5 mm superior on the anterior glenoid. Biomechanical testing was done in two positions of humeral elevation in the scapular plane, three positions of humeral rotation, and with an externally applied joint compression load of 22 N. Glenohumeral motion was measured in the intact state, after creation of the simulated Bankart lesion, and after each of the two anterior capsular shifts. Both the superior and medial shifts of the capsule decreased anterior glenohumeral translation to equivalent extents. For posterior and inferior translation at 45 degrees elevation, the superior shift significantly decreased translation to a greater extent than did the medial shift.

[Estramustine phosphate, estrogen conjugated with nitrogen mustard inhibits the growth of endometrial cancer cells in vitro]

Estra-1,3,5 (10)-triene-3,17-diol (17 beta)-, 3-[bis(2-chloroethyl) carbamate] (Estramustine EM) was tested for its anticancer effect on human endometrial cancer cell lines: Ishikawa and its estrogen (E) independent sub-clone EIIL (Estrogen Independent Ishikawa Line). The results showed: (1) EM inhibited growth of both cell lines in a dose dependent manner giving ID50 for Ishikawa as 12 microM and for EIIL as 65 microM. (2) The addition of EM to the culture medium caused cell detachment and death associated with a breakdown of DNA to approximately 90 base pair fragments. (3) Reverse transcription-polymerase chain reaction to examine expressions of c-erbB-2, nidogen and fas showed that EM completely abolished fas expression and resulted in a 40% decrease in nidogen expression in Ishikawa but not in EIIL. No change was seen in c-erbB-2 expression. The present data indicate that the E component of EM does not stimulate the growth of Ishikawa or EIIL. Since the growth of both cell lines was inhibited but apparently in an E receptor (ER) dependent manner, EM may be of value in an adjuvant therapy for endometrial cancer, especially an ER positive one.

Effects of caffeine or EDTA post-treatment on EMS mutagenesis in soybean

Seeds of soybean cultivar LD4 were mutagenically treated with EMS (0.3, 0.5, 0.6, 0.9, 1.5 and 1.8%) for 3 h only or plus caffeine (50 mM) or EDTA (1 mM) post-treatment for 5 h. The experimental results indicated that: (1) of the different concentrations of EMS treatment, the M2 mutation frequency induced with 0.6% EMS was the highest (9.7%). When the EMS concentration was over 0.9%, the mutation frequency decreased rapidly. (2) Of the EMS treatments plus caffeine or EDTA post-treatment, the mutagenic effect of 0.6% EMS was the best for inducing morphological variations. Caffeine post-treatment decreased notably the mutation frequency of EMS treatment; when concentrations of EMS were very high (1.5% and 1.8%), mutation frequencies of EDTA post-treatment were still 5.0% and 4.88%, but no mutants were found in EMS treatment or plus caffeine post-treatment. (3) In the M2 mutation spectrum, 11 kinds of mutant types were observed in EMS treatment or plus caffeine or EDTA post-treatment. Relative frequencies of some mutant types (growth period, plant height, grain size, leaf shape and sterility, etc.) were similar among the three treatments, but EDTA post-treatment could change the relative frequencies of yield characteristics (number of pods and grains, grain weight/plant) induced by EMS treatment only.

[Establishment of metastatic sub-clone from estrogen independent Ishikawa cells and its characterization in vitro and in vivo]

An estrogen (E) independent sub-clone (EIIL) was separated from a human endometrial carcinoma cell line, Ishikawa, by culturing the wild type under an E free condition for 350 days. The cells were then implanted into nude mice subcutaneously and tumors allowed to develop for 35 days. The primary lesions were then excised to stimulate recurrence. One animal developed recurrence with multiple distant metastases. The primary tumor and metastatic tumors from the animal were studied for ErbB-2 expression by immunohystochemical techniques or by a reverse transcription followed by polymerase chain reaction (RT-PCR). Expressions of epidermal growth factor (EGF) receptors, aromatase, nidogen, E receptors, hepatocyte growth factors (HGF) and beta-actin were also examined. The results showed that metastatic lesions expressed high levels of ErbB-2, nidogen and aromatase but unchanged levels of EGF receptors and HGF. The metastatic lesions expressed one third of the E receptors which were detected in the EIIL in vitro. These observations suggest that a decrease in ER along with increased expression of nidogen and aromatase is associated with the process of metastasis and the model appears to be of value in studying the process of the acquisition of a metastatic phenotype.

Localization of atherosclerosis in arterial junctions. Concentration distribution of low density lipoproteins at the luminal surface in regions of disturbed flow

To investigate the role of fluid mechanical factors in atherogenesis and anastomotic intimal hyperplasia, the effect of blood flow on the transfer of low density lipoproteins from flowing blood to the luminal surface was studied theoretically using a two dimensional T-junction model. The flow fields in the junction were obtained by solving the Navier-Stokes equations numerically and the concentration distribution of low density lipoproteins at the luminal surface was determined using a finite difference analysis. The transfer of low density lipoproteins from flowing blood to the surface of the vessel wall was greatly enhanced in the two regions of disturbed flow, one in the main vessel, the other in the subsidiary vessel. The highest concentration of low density lipoproteins on the inner surface of the vessel wall was predicted to occur in the areas of the reattachment points. The slower the recirculation flow, the higher the lipid accumulation at the luminal surface in the disturbed flow regions and the wider the highly concentrated low density lipoprotein area. In summary, the authors' mathematical model predicts that locally disturbed blood flows at arterial bifurcations and surgically created junctions provide favorable conditions for the accumulation of atherogenic substances at the luminal surface, thus increasing the potential for lipid infiltration into the vessel wall.

Validation of miniature ultrasonic transit-time flow probes for measurement of renal blood flow in rats

This study validates the accuracy of miniature ultrasonic transit-time flow probes for measuring renal blood flow (RBF) in the rat. Probes for 1-mm and 2-mm vessels were calibrated ex vivo using excised arteries at varying flow rates and hematocrit (Hct). Correlation between measured and true flow rates for the 2-mm probe were identical (r = 1.0) at both normal and subnormal Hct values. Correlation for the 1-mm probe was high (r = 0.994) at normal Hct, but varied at both high flow rates and subnormal Hct values. In vivo correlation of RBF measurements using the 1-mm probe with the clearance and extraction of p-aminohippuric acid showed a high correlation (r = 0.84; n = 72, P < 0.0001) over a wide range of flow rates (0.5-21 ml/min) and Hct (36-74%). Zero flow levels remained steady, averaging -0.2 +/- 0.2 ml/min during occlusion in the living animal and -0.1 +/- 0.3 ml/min after exsanguination. This study shows that the ultrasonic transit-time flowmeter (1-mm and 2-mm probes) is a reasonably accurate and reliable method with which to measure RBF in the anesthetized, acute-instrumented rat.

Luminal surface concentration of lipoprotein (LDL) and its effect on the wall uptake of cholesterol by canine carotid arteries

PURPOSE

The effect of near-wall blood flow velocity and plasma filtration velocity across the arterial wall on luminal surface concentration of low-density lipoproteins (LDL) and the uptake of tritium-cholesterol were investigated.

METHODS

A numeric analysis of LDL transport in steady flow, over the range of physiologically relevant flow rates, predicted a surface concentration of LDL of 4% to 16% greater than that in the bulk flow. The LDL surface concentration increased linearly with filtration velocity and inversely with wall shear rate.

RESULTS

These were validated experimentally in canine carotid arteries. When the transmural pressure was increased from 100 to 200 mm Hg, the filtration velocity increased from 5.13 x 10(-6) cm/sec to 8.41 x 10(-6) cm/sec, whereas the normalized uptake rate of tritium-cholesterol increased from 3.58 x 10(-4) cm/hour to 7.36 x 10(-4) cm/hour.

CONCLUSION

These results indicate that lipids accumulate at the luminal surface in areas where blood flow velocity and wall shear stress are low and where the permeability of the endothelial layer is enhanced. Moreover, the rate of lipid infiltration into the blood vessel walls is affected by the luminal surface concentration. These findings are consistent with chronic hypertension and elevated blood cholesterol concentrations being major risk factors for atherosclerosis.

Structure and oxygen sensitivity of nifLA promoter of Enterobacter cloacae

The nucleotide sequence of the nifLA promoter of Enterobacter cloacae E26 was determined, and the transcription start site of nifLA was mapped by the primer extension. Studies on the oxygen regulation of E. cloacae nifLA promoter with the nifL'-lacZ fusion showed that the nifLA promoter was sensitive to oxygen as Klebsiella pneumoniae nifLA promoter reported previously. Comparison between the nifLA promoter sequences of E. cloacae and K. pneumoniae revealed the presence of an 11-bp conserved sequence between the -24/-12 consensus of sigma 54-dependent promoter and NtrC binding motif. The 11-bp sequence is speculated to be involved in the oxygen regulation of the nifLA promoter of both enteric bacteria.

Biomechanical evaluation of a simulated Bankart lesion

The purpose of this study was to determine the effect of sectioning of the anterior part of the inferior glenohumeral ligament (a simulated Bankart lesion) on load-induced multidirectional glenohumeral motion. Nine fresh, intact cadaveric shoulders were tested on a special apparatus that constrained three rotations but allowed simultaneous measurement of anterior-posterior, superior-inferior, and medial-lateral translation. Coupled anterior-posterior and superior-posterior translations were recorded while anterior, posterior, superior, and inferior forces of fifty newtons were applied sequentially. Testing was done in three positions of humeral elevation in the scapular plane, in three positions of humeral rotation, and with an externally applied joint-compression load of twenty-two newtons. A liquid-metal strain-gauge was placed on the posterior band of the inferior glenohumeral ligament to assess concomitant posterior capsular strain during the various test conditions. All shoulders were tested intact and again after the inferior glenohumeral ligament and the labrum had been detached from the glenoid from just superior to the anterior band of the inferior glenohumeral ligament to a point just posterior to the infraglenoid tubercle. The simulated Bankart lesion resulted in selected increases in anterior translation at all positions of elevation, in posterior translation at 90 degrees of elevation, and in inferior translation at all positions of elevation. However, these increases were very small; the maximum mean increase in translation seen over-all was only 3.4 millimeters, which occurred during inferior translation at 45 degrees of elevation.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of Baji Zibugao on the serum levels of endocrines in thyroidectomized (yang deficiency) rabbits]

In order to study the effect of Baji Zibugao (BJZBG, a medicinal plaster mainly consisting of Radix Morindae Officinalis) on the endocrine functions of hypothyroid rabbits, we determined the serum levels of thyroxine (T4), triiodothyronine (T3), cAMP, cGMP and corticosterone in three groups of rabbits: total thyroidectomized and untreated (group I), total thyroidectomized and treated with BJZBG (group II) and controls (group III). The results showed: (1) The serum level of T4 in group I and II after operation was significantly lower than that before operation (P < 0.005), and the serum level of T3 in group I was also lower than that before operation (P < 0.02), but the change of T3 in group II after operation was not significant (P > 0.05); (2) The serum cAMP level in group I after operation decreased and the cGMP level increased (P < 0.025), but the changes of cAMP and cGMP level in group II after operation were not significant (P > 0.05), (3) The change of serum corticosterone level in group I or II after operation was not remarkable (P > 0.05).

Longitudinal forces acting on a knitted polyester arterial prosthesis when implanted as a thoracic aorta substitute in the dog

The longitudinal forces under which arterial prostheses are held in situ are of great importance. The tension caused by the longitudinal force may be one of the factors involved in the formation of anastomotic false aneurysms. In order to measure the changes in the longitudinal force at both proximal and distal end-to-end anastomoses over different periods of implantation, we devised an experimental study in which the changes in length of a warp-knitted polyester VP1200K (Vascutek Ltd., Inchinnan, Scotland) arterial prosthesis, used as a thoracic aorta substitute in the dog, were recorded photographically at implantation and removal. The longitudinal forces acting at the two sites were then calculated using a linear relationship between the longitudinal force and the changes in length of a virgin prosthesis, which was found experimentally in vitro using a computerized laser calibration system. One-tailed Student's t-test showed no significant difference between the length indicator values at the two anastomotic sites at different periods of implantation except during the 1-month period. Textile analysis of the explanted prostheses and histopathologic observations confirmed this similar behavior at the two anastomotic sites. These observations were contrary to the theoretic prediction regarding the effect of forces applied by drag and tissue ingrowth. Nevertheless, analysis of variance confirmed that there was no difference evident at the two sites between different implantation periods. These observations may explain why the formation of anastomotic false aneurysms is less common at end-to-end anastomoses.

Renal vasoconstriction during inhibition of NO synthase: effects of dietary salt

Since dietary salt loading enhances nitric oxide (NO) generation in the kidney, we investigated the hypothesis that changes in salt intake have specific effects on vascular resistance in the kidney mediated by the L-arginine-NO pathway. We contrasted changes in renal and hindquarter vascular resistances (RVR and HQVR) in anesthetized rats during intravenous infusions of graded doses of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). Groups (N = 8 to 10) of rats were maintained on a high salt (HS) or low salt (LS) diet for two weeks. Compared to those on LS, rats on HS had a greater increase in mean arterial pressure (delta MAP; +32 +/- 4 vs. +22 +/- 3%; P = 0.05) and RVR (+160 +/- 17 vs. +83 +/- 10%; P < 0.005) and a greater fall in renal blood flow (delta RBF; -47 +/- 3 vs. -32 +/- 4%; P < 0.01); changes in HQVR were similar in the two groups. The enhanced RVR response to L-NAME in HS rats could not be ascribed to the higher renal perfusion pressure (RPP) since it persisted in rats whose RPP was controlled by adjustment of a suprarenal aortic clamp. Changes in RVR with an NO donor (SIN-1) were similar in HS and LS rats. L-NAME reduced plasma renin activity in both HS and LS rats. After inhibition of ACE with captopril, or of angiotensin II type I (AT1) receptor with losartan, the increase in RVR with L-NAME remained greater in HS than LS rats.(ABSTRACT TRUNCATED AT 250 WORDS)

[The phenotypic change of smooth muscle cells in the media of pulmonary intra-acinar arteries during hypoxia]

The phenotypic change of smooth muscle cells (SMCs) in the media of pulmonary intraacinar arteries (IAA) was observed in rats during hypoxia. From 3 to 40 exposure days, pulmonary arterial pressure (PAP) and right ventricular hypertrophy increased parallely. From 1 to 5 exposure days, SMCs still displayed the "contractile" phenotype, but the amount of intercellular collagen slightly increased. After 7 exposure days, some medial SMCs changed into the "fully" or "partially" "synthetic" phenotype with an excess of intercellular collagen. From 14 to 40 exposure days, other than some SMCs of partially "synthetic" phenotype, a great number of SMCs acquired the "contractile" phenotype characteristics, but the synthetic and secretive organelles and intercellular collagen were still more than those in the groups from 1 to 5 exposure days. Our results suggested that along with the prolongation of hypoxic exposure, the kinetic changes of SMC phenotype might not parallel with PAP change.

Uptake of 3H-7-cholesterol along the arterial wall at an area of stenosis

Abnormal uptake of atherogenic substances and lipid infiltration have been believed to contribute to the localized genesis and development of atherosclerosis, as well as to late failures of synthetic arterial prostheses. To verify the theoretical prediction that accumulation of lipoproteins on the luminal surface of arterial walls occurs in the regions of disturbed flow, we have carried out an in vitro mass transfer experiment to test the effect of a pseudo steady recirculation flow on the uptake of 3H-7-cholesterol by the arterial wall at a surgically created stenosis. It was found that, as predicted by the theory, in the flow field of the stenosis the uptake of labeled cholesterol reached a maximum around the reattachment point of the vortex distal to the stenosis, where the wall shear stress was lowest (zero). This value of the highest uptake rate was almost twice the average, whereas the uptake level was at a minimum at the stenosis itself where the wall shear stress was highest. The lowest uptake was only 60% of the average. These results provide strong support to our hypothesis, based upon the theory that, in addition to the flow induced changes to the biologic function of endothelial cells, the disturbed flow with slow recirculation itself favors the accumulation of atherogenic lipoproteins at the blood-endothelium boundary, therefore playing an important role in the localized pathogenesis and development of atherosclerosis.

Monoclonal antibody to murine PECAM-1 (CD31) blocks acute inflammation in vivo

A murine model of peritonitis was used to test the role of platelet/endothelial cell adhesion molecule 1 (PECAM-1/CD31) in acute inflammation. A monoclonal antibody (mAb) specific for murine PECAM-1 injected intravenously 4 h before the intraperitoneal injection of thioglycollate broth blocked leukocyte emigration into the peritoneal cavity for up to 48 h. This block was particularly evident for neutrophils. Control mAb, including one that bound to murine CD18 without blocking its function, failed to block emigration when used at the same or higher concentrations. The decreased emigration seen with the anti-PECAM-1 antibody was not due to neutropenia or neutrophil sequestration in the lung, spleen, or other organs; peripheral blood leukocyte counts were not diminished in these mice. In the mesenteric venules of the mice treated with anti-PECAM-1 mAb, leukocytes were frequently seen in association with the luminal surface of the vessel, but did not appear to emigrate. Thus, the requirement for PECAM-1 in the transendothelial migration of leukocytes previously seen in an in vitro model holds true in this in vivo model of acute inflammation.

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.