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D Z Xiang

Publications and source records attributed to D Z Xiang.

11 recordsLinked to original sources
PubMed2001

Sleeve-related thrombosis: a new form of catheter-related thrombosis.

In a detailed study of central venous catheter-related sleeve and thrombosis in experimental animals, a new form of thrombosis was detected and termed sleeve-related thrombosis. A silastic catheter was placed in the jugular vein and the anterior vena cava of 22 rabbits and 54 rats. After intervals of 1, 3, 7 days, 2, 3, 4 weeks and 1, 2, 4, 6 months the veins were examined by light microscopy and by transmission electron microscopy. In about 50% of the rats a thrombus was observed at the end of the catheter sleeve. Consecutive cutting allowed the visualization of a transition from a sleeve via part of sleeve and part of thrombus to a pure thrombus. This thrombus was separated from the vein wall and could not be considered a mural thrombus. As the thrombus was only attached to the terminal part of the organized catheter sleeve we propose the name sleeve-related thrombosis.

Animals↗
PubMed2000

Intimal hyperplasia after long-term venous catheterization.

OBJECTIVE: Intimal hyperplasia is a well-known consequence of arterial injury and arterialization in vein grafts. However, the subacute and chronic vein wall changes which occur after catheterization have not been well studied. In this animal study, intimal hyperplasia in the vein wall after catheterization was examined. METHODS: A silicon catheter was placed in the anterior caval vein of 54 rats. After in situ fixation at scheduled intervals (1 day to 6 months), the pathologic changes in the vein wall were studied on semi-serial histology sections by means of light microscopy. RESULTS: Three forms of intimal hyperplasia could be observed: plaque-like, papillary-like and incorporation of the mural part of the sleeve into the underlying vein wall. Although the appearance of each was different, their composition was identical. All were mainly composed of alpha-actin-positive cells and collagen localized above the internal elastin layer, and covered by endothelium if facing the lumen. The plaque-like and papillary-like forms were mainly localized in the anterior vena cava, while sleeve incorporation mainly occurred in the jugular vein. Plaque-like and papillary-like intimal hyperplasia could be seen together on the same slide, but these two forms were never seen together with sleeve incorporation. CONCLUSION: Intimal hyperplasia occurs after venous catheterization and is probably caused by chronic injury to the vein wall due to knocking and rubbing movements of the catheter against the wall.

Actins↗
PubMed1998

Composition and formation of the sleeve enveloping a central venous catheter.

PURPOSE: After catheterization, 42% to 100% of central venous catheters are surrounded by a "fibrin sleeve." This sleeve has been considered the cause of catheter-related infections, withdrawal occlusion, and pulmonary embolism. The reactions between the vein wall and the catheter were studied. METHODS: A silicone catheter was placed in the anterior caval vein of 123 rats. After in situ fixation at scheduled intervals, the pathologic changes were studied on semi-serial histologic sections by means of light microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). In 36 rats, the catheter was withdrawn immediately; in 72 rats, it was left in situ up to 6 months; and in 15 rats, the study was performed up to 10 months after withdrawal of a catheter that had remained in situ for 6 months. RESULTS: In the group in which the catheter was withdrawn immediately, mural thrombi disappeared by day 7. In the group in which the catheter remained in situ, thrombi remained around the proximal portion of the catheter. This pericatheter thrombosis (PCT) was invaded by migrating and proliferating smooth muscle cells (SMCs), originating from an injured vein wall, and transformed from day 7 into a tissue composed predominantly of SMCs and collagen and covered by endothelial cells. Later, the number of cells decreased, and the relative amount of collagen increased. Up to 10 months after withdrawal of the catheter, the collapsed sleeve was still present within the vein. CONCLUSION: The sleeve around a central venous catheter is not a fibrin sleeve, but a stable cellular-collagen tissue covered by endothelium. It is mainly formed by smooth muscle cells migrating from the injured vein wall into the early pericatheter thrombus.

Animals↗
PubMed1992

Structure function analysis of vitamin D analogs with C-ring modifications.

Analogs of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2D3) with substitutions on C-11 were synthesized. Small apolar substitutions (11 alpha-methyl, 11 alpha-fluoromethyl) did not markedly decrease the affinity for the vitamin D receptor, but larger (11 alpha-chloromethyl or 11 alpha- or 11 beta-phenyl) or more polar substitutions (11 alpha-hydroxymethyl, 11 alpha-(2-hydroxyethyl] decreased the affinity to less than 5% of that of 1 alpha,25-OH)2D3. Their affinity for the vitamin D-binding protein, however, increased up to 4-fold. The biological activity of 11 alpha-methyl-1 alpha,25-(OH)2D3 closely resembled that of the natural hormone on normal and leukemic cell proliferation and bone resorption, whereas its in vivo effect on calcium metabolism of the rachitic chick was about 50% of that of 1 alpha,25-(OH)2D3. The 11 beta-methyl analog had a greater than 10-fold lower activity. The differentiating effects of the other C-11 analogs on human promyeloid leukemia cells (HL-60) agreed well with their bone-resorbing activity and receptor affinity, but they demonstrated lower calcemic effects in vivo. Large or polar substitutions on C-11 of 1 alpha,25-(OH)2D3 thus impair the binding of the vitamin D receptor but increase the affinity to vitamin D-binding protein. The effects of many C-11-substituted 1 alpha,25-(OH)2D3 analogs on HL-60 cell differentiation exceeded their activity on calcium metabolism.

Animals↗
PubMed1992

Polyunsaturated fatty acids decrease the apparent affinity of vitamin D metabolites for human vitamin D-binding protein.

The affinity of purified human vitamin D-binding protein from serum (DBP) for 25-hydroxyvitamin D3 (25-OHD3) and 1 alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] was measured in the presence of free fatty acids (FFA), cholesterol, prostaglandins and several drugs. Mono- and polyunsaturated fatty acids markedly decreased the affinity of both 25-OHD3 and 1,25-(OH)2D3 for DBP, whereas saturated fatty acids (stearic and arachidic acid), cholesterol, cholesterol esters, retinol, retinoic acid and prostaglandins (A1 and E1) did not affect the apparent affinity. Several chemicals known to decrease the binding of thyroxine to its plasma-binding protein did not affect the affinity of DBP. The apparent affinity of DBP for both 25-OHD3 and 1,25-(OH)2D3 decreased 2.4- to 4.6-fold in the presence of 36 microM of linoleic or arachidonic acid, respectively. Only a molar ratio of FFA:DBP higher than 10,000 was able to decrease the binding of 25-OHD3 to DBP by 20%. Much smaller ratio's of FFA:DBP (25 for arachidonic and 45 for oleic acid), however, decreased the binding of 1,25-(OH)2D3 to DBP. These latter ratio's are well within the physiological range. The addition of human albumin in a physiological albumin:DBP molar ratio did not impair the inhibitory effect of linoleic acid on the binding of [3H]25-OHD3 to DBP. The binding and bioavailability of vitamin D metabolites thus might be altered by mono- and polyunsaturated but not by saturated fatty acids.

Albumins↗
PubMed1991

Vitamin D analogs with low affinity for the vitamin D binding protein: enhanced in vitro and decreased in vivo activity.

The affinity of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] and analogs with side-chain modifications [MC 903 or calcipotriol, MC 1147 or 24,24-dihomo-1 alpha,25-(OH)2D3 and 1,25-(OH)2-16ene-23yne-D3] for the vitamin D receptor and the serum vitamin D binding protein (DBP) were compared. The affinity of MC 903 for the receptor from chick and rat duodenum or from human peripheral blood mononuclear cells or HL-60 cells varied between 60 and 100% relative to the affinity of 1,25-(OH)2D3. The relative affinity of 1,25-(OH)2-16ene-23yne-D3 and MC 1147 varied for the same receptors between 45-70 and 3.5-25%, respectively. The relative affinity of MC 903 for human DBP was 30-fold decreased, whereas the two other analogs did not bind to DBP at all even in more than 1000-fold excess. The in vitro biologic activity of 1 alpha,25-(OH)2D3 on phytohemagglutinin-stimulated normal human lymphocyte proliferation was markedly inhibited by the addition of physiologic amounts of DBP to the cell culture medium. No such inhibition was observed when MC 903 or 1147 was evaluated similarly. DBP therefore reversed the rank order of the in vitro potency of these analogs. Intramuscular injections for 10 consecutive days to vitamin D-deficient chicks demonstrated a greater than or equal to 100-fold lower biologic activity of MC 903, MC 1147, and 1,25-(OH)2-16ene-23yne-D3 compared to that of 1 alpha,25-(OH)2D3 as evaluated by serum calcium and osteocalcin concentrations, as well as by duodenal calbindin D28K and bone calcium content.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Blood rheology during an intensified conventional insulin treatment (ICIT) in insulin-dependent diabetes.

Fifteen insulin-dependent diabetes mellitus (IDDM) patients with minor diabetic complications underwent an intensified conventional insulin treatment (ICIT) program consisting of multiple daily insulin injections with an insulin pen. Blood viscosity parameters were measured before the start, after 6 weeks, 1 and 2 years with a Contraves LS30 viscosimeter. At the start several rheological parameters were disturbed in the diabetic subjects. Mean total hemoglobin A1 (HbA1) significantly (at least P less than 0.05) decreased while the plasma free insulin level significantly increased (at least P less than 0.05) under ICIT. During the first 6 weeks hematocrit (P less than 0.01), plasma (P less than 0.05), whole blood (P less than 0.05) and erythrocyte (P less than 0.01) viscosities significantly decreased but they increased again at 1 year of ICIT. Only plasma viscosity (P less than 0.05) remained below the starting value after 1 and 2 years. Normalization of the blood sugar level improved plasma and whole blood viscosity by an insulin-induced dilution phenomenon after 6 weeks. The persisting decrease in plasma viscosity was accompanied by a significant alteration of the plasma protein profile. These findings suggest that metabolic status influences blood rheology in IDDM patients but by different mechanisms on a short- or long-term basis.

Adult↗
PubMed1989

Blood viscosity in human obesity: relation to glucose tolerance and insulin status.

Obesity is known to be associated with an elevated risk for cardiovascular disease. Rheological disturbances could be factors contributing to these vascular complications. Therefore we have evaluated blood viscosity parameters in 128 obese (BMI greater than 28 kg/m2) adults and in 90 non-obese healthy subjects. Whole blood, plasma and erythrocyte viscosity values were determined with a Contraves LS30 viscosimeter. Plasma and whole blood viscosity were significantly (all P less than 0.001) increased in the obese subjects. The increased low shear erythrocyte viscosity suggested a diminished erythrocyte deformability in obesity. The rheological abnormalities were present even in the absence of impaired glucose tolerance, diabetes, hypertension or hyperlipidaemia. In the obese group the rheological parameters showed significant correlations (at least P less than 0.05) with BMI, insulin or C-peptide area during an oral glucose tolerance test and plasma lipids. Our findings demonstrate that obesity per se may be associated with abnormal blood viscosity properties.

Adult↗
PubMed1984

The frequency of major psychiatric disorder in Chinese inpatients.

The authors applied DSM-III criteria to 268 consecutive Chinese inpatients. Nearly a quarter had affective disorder, a third had schizophrenia, and, except for one patient, none had alcoholism or drug abuse. The authors discuss the factors influencing hospitalization in China.

Adult↗