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Biomedical subjects

S C Tang

Publications and source records attributed to S C Tang.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Serum apolipoprotein abnormalities in patients with idiopathic nephrotic syndrome].

We measured serum lipid and apolipoprotein (apo) levels in 45 patients with normal renal function at different stages of idiopathic nephrotic syndrome (NS). Wide abnormalities of lipid metabolism were found. The characteristic disorder of serum apos in NS was a decrease in apoAI and AII and a significant increase in apoB, CII, and CIII. Consequently, the ratio of apoAI to apoB was significantly decreased. Some patients with NS in remission had normal serum lipid concentrations, but abnormalities of serum apos were still observed. It is suggested that the nephrotic patients may be at increasing risk for coronary heart disease (CHD), and that apos may be more sensitive predicators of CHD than lipids.

Adolescent↗
PubMed1993

Dynamic observations on NK cell activity and IL-2 and IFN gamma production in vitro in patients on maintenance hemodialysis.

In order to study the immune function of patients on maintenance hemodialysis (MHD), we assayed NK cell cytotoxicity against K562 targets in 40 patients on MHD, and the production of IL-2 and IFN in peripheral blood mononuclear cells (PBMC) after PHA stimulation, in contrast to those in normal controls. The results showed that NK cell activity and IL-2 and IFN levels were markedly lower in the patients than in the controls. After a single dialysis, NK cell activity as well as IL-2 and IFN levels were elevated to different extent. But there was no significant change in patients after long-term dialysis. There was a positive correlation between the NK cell activity and IL-2 and IFN activity in the controls, but no such correlation was found in the patients on MHD. There was a positive correlation between the NK cell activity and IL-2 activity in patients after dialysis, suggesting that immune function were impaired in the patients on MHD, with a decline in the activity of NK cell and IL-2 and IFN, and a disorder of immune regulation cycle. These abnormal immune impairments in the patients could be partly corrected by hemodialysis. However, long-term hemodialysis is not much helpful in the improvement of patient's immune function.

Adult↗
PubMed1993

Correlative factors of left ventricular hypertrophy in end-stage renal disease.

The correlative factors of left ventricular hypertrophy (LVH) in 287 end-stage renal disease (ESRD), admitted from 1983 to 1992, were analyzed. 52% of patients had LVH including 54% of patients on hemodialysis, 75% of patients with peritoneal dialysis and 38% of transplanted patients. Single factor analysis indicated that age, blood pressure, serum creatinine and BUN, hemoglobin, serum alkaline phosphatase, aortic valve disease and present DSRD therapy were related to LVH. Multiple logistic regression analysis indicated that the most important factors which independently related to LVH in all patients studied, were management of present ESRD treatment, age, hypertension and high serum alkaline phosphatase. In a subset of patients with severe LVH, high serum alkaline phosphatase level, high systolic blood pressure and age were the predictive factors. In patients on dialysis, the most important variable were age and high serum alkaline phosphatase. Hypertension was the sole predictor of LVH in the transplant group.

Adult↗
PubMed1993

High-affinity substance P binding sites of neurokinin-1 receptor type autoradiographically associated with vascular sinuses and high endothelial venules of human lymphoid tissues.

BACKGROUND: Factors that affect leukocyte-endothelial cell interaction in high endothelial postcapillary venules and vascular sinuses of lymphatic tissues indirectly regulate immune function. Studies in sheep demonstrated that acute infusion of substance P (SP) into cannulated popliteal lymph node afferent lymphathics produced a marked and prolonged increase in the output of lymphocytes into nodal efferent lymph. The proposed mechanism is an influence of SP on lymph vascular systems. Such functional importance of the immunoregulatory properties of SP in man is unknown. EXPERIMENTAL DESIGN: The expression and distribution of SP receptors in human lymphoid tissue was investigated using slide-mounted fresh-frozen sections of lymph node, hyperplastic tonsillitis, and spleen for ligand binding and autoradiographic studies. RESULTS: Specific binding of radiolabeled SP to lymph node and tonsils reached a plateau within approximately 40 minutes, being half-maximal at 20 minutes. The specific binding was between 65 and 75% of total binding. In contrast, iodinated neurokinin A under identical incubation conditions, did not significantly associate with the tissues. Neither the SP nor the neurokinin A tracer specifically associated with spleen. Binding specificity of radiolabeled SP was analyzed in binding competition experiments. Synthetic SP, SP (3-11), a selective neurokinin-1 agonist and a neurokinin-1 antagonist competed with the specific binding of SP to lymph node and tonsil sections. The half-maximal inhibition of binding was obtained at a concentration of about 0.5 nmol/liter of SP. The fragment SP (1-4) and selective neurokinin-2 ligands did not compete with the specific binding of SP. Scatchard and nonlinear algorithm analyses revealed two binding sites for SP. For lymph node and tonsil, one site showed a high affinity of about 0.4 nmol/liter and 0.7 nmol/liter and a low capacity for SP, respectively. The second site exhibited a lower affinity of 100 nmol/liter and 50 nmol/liter and a higher capacity for SP in lymph node and tonsil, respectively. Autoradiographic localization of the binding sites shows a very high concentration of silver grains when compared with controls. The reaction occurred mainly over vascular sinuses and high endothelial venules with heterogenous density. Silver grain accumulation was also noticed over the marginal sinuses of the B cell follicles. CONCLUSIONS: The biochemical results indicate the presence of neurokinin-1 receptors in human lymph node and tonsil. We suggest that the neurokinin-1 receptors localized to vascular tissues of lymph node and tonsil mediate the affects of SP on lymphocyte traffic, and we propose that SP plays a regulatory role in lymphocyte homing in man.

Autoradiography↗
PubMed1992

Regulation of human T lymphoblast growth by sensory neuropeptides: augmentation of cholecystokinin-induced inhibition of Molt-4 proliferation by somatostatin and vasoactive intestinal peptide in vitro.

The effects on proliferation of Molt-4 lymphoblasts of cholecystokinin (CCK-8), somatostatin-14 (SS), vasoactive intestinal peptide (VIP) and substance P (SP) were investigated using different combinations of the peptides, peptide analogs and their antagonists. In vitro proliferation of the cells was measured by a colorimetric assay for cell growth and survival. Results indicate that SP and SP (3-11) stimulated, whereas CCK-8, VIP and SS inhibited, proliferation in a dose-dependent manner (P < 0.05). Unsulfated CCK-8 had no effect on growth of Molt-4 lymphoblasts, and a specific antagonist of CCK, at a concentration 10(-6) M, diminished the inhibitory effect of CCK-8 on Molt lymphoblasts (P < 0.05). This suggests that the inhibitory action of CCK-8 was mediated by peripheral-type CCK receptors. SS and VIP, at equimolar concentrations of 10(-6) M, significantly augmented the CCK-8-induced inhibition of Molt-4 lymphoblast proliferation. However, none of the inhibiting neuropeptides suppressed stimulation of Molt-4 lymphoblast proliferation in response to SP. These data suggest a role of sensory neuropeptides including CCK in modulating human T lymphoblast proliferation during neuroendocrine interactions with the immune system.

Humans↗
PubMed1990

Myristic acid is incorporated into the two acylatable domains of the functional glycoprotein CD9 in ester, but not in amide bonds.

CD9 is a signal-initiating glycoprotein of uncertain membrane insertion which contains more than one locus of acylation and is distinguished by being the major acylatable platelet protein. The N-terminus of CD9 is blocked to Edman degradation. We investigated whether [3H]myristic acid could be incorporated into CD9, whether that incorporation occurred via an amide linkage, and whether myristate and palmitate were differentially incorporated into the two domains. Pulse-labeling studies, performed on the human osteogenic sarcoma cell line SKOSC which expresses 22 and 24 kDa variants of CD9 demonstrated that the respective precursors of 20.5 and 23 kDa were not radiolabeled by either [3H]myristic acid or [3H]palmitic acid, but that both fatty acids could be ligated to CD9 during the later stages of protein maturation. The failure to incorporate myristic acid cotranslationally suggest that CD9 does not contain amino-terminal amide-bonded myristic acid. Incorporation of radiolabel from both fatty acids proceeded very rapidly and could be visualized after a 10 s pulse. Although myristic acid was partially metabolized into palmitic acid, incorporation of authentic [3H]myristate into CD9 could be demonstrated. The myristic acid bonds were shown to be as sensitive to hydroxylamine treatment as those linking palmitate. Both fatty acids were also incorporated into CD9 in hydroxylamine-sensitive bonds in the presence of cycloheximide, reaching 30-40% of the levels in untreated controls. The sensitivity of myristate ligands to hydroxylamine demonstrates that this fatty acid is not linked via amide, but rather via ester bonds. The sensitivity of [3H]myristate and [3H]palmitate bonds to 2-mercaptoethanol further suggests that either fatty acid is linked via thioester rather than hydroxyester bonds to each domain on CD9. Limited proteolysis analysis with Staphylococcus aureus V8 proteinase of CD9, labeled in the absence or presence of cycloheximide, showed that [3H]myristic acid and [3H]palmitic acid labeled identical peptides, and to the same extent, suggesting that myristate is an alternative substrate for the transacylase(s) involved.

Acylation↗
PubMed1990

Diagnostic contrast echocardiography in children with congenital heart disease.

905 diagnostic contrast echocardiographic studies (DCE) were performed on 223 children. Carbon dioxide microbubble was used as contrast agent in various age groups, especially in newborns and infants because of its safety in application, stable contrast effect, and peripheral vein injection. Two-dimensional echocardiography (2-DCE), a useful tool in diagnosis of left to right shunt lesions reduced false negative diagnoses for ventricular septal defects and eliminated false positive diagnosis for atrial septal defects and patent ductus arteriosus. The accuracy of diagnosis in this series was 97%. The results of this series showed that 2-DCE is also valuable in the diagnosis of congenital heart disease with right to left shunts, and can be used to evaluate shunt levels and determine the obstructive sites on the right side of the heart.

Adolescent↗
PubMed1989

Evidence that monoclonal antibodies against CD9 antigen induce specific association between CD9 and the platelet glycoprotein IIb-IIIa complex.

Monoclonal antibodies to the CD9 antigen are powerful platelet agonists. We report here the novel finding that the anti-CD9 monoclonal antibodies 50H.19 and ALB6 promote physical association between CD9 antigen and the glycoprotein IIb-IIIa complex (GPIIb-IIIa) component of the platelet fibrinogen receptor. The monoclonal antibodies do not consistently immunoprecipitate proteins other than CD9 from 125I-labeled human platelets even if the platelets are first treated with the homobifunctional cross-linking reagent dithiobis(succinimidyl propionate), indicating that CD9 antigen is not physically associated with other membrane proteins in the resting state. However, the addition of agonistic concentrations of either monoclonal antibody before cross-linking results in the coprecipitation of proteins corresponding in mobility and peptide composition to GPIIb, and GPIIIa. The association of CD9 with the GPIIb-IIIa complex is unaffected by a combination of aspirin and ADP scavengers sufficient to abrogate anti-CD9 monoclonal antibody-induced platelet aggregation, and is therefore not dependent upon thromboxane- and ADP-mediated pathways of intracellular signalling. The specificity of the association is demonstrated by the lack of other coprecipitating major proteins, by the requirement for induction by anti-CD9 monoclonal antibodies, and by the failure to promote reciprocal association with either of the anti-GPIIb-IIIa complex monoclonal antibodies P2 or HuP1-m1a.

Antibodies, Monoclonal↗
PubMed1989

[Quantification of pulmonary to systemic flow ratio (Qp/Qs) in children with patent ductus arteriosus by echocardiography].

The assessment of left-right ductal shunting flow in 35 children with PDA by 2-DCE with 35 normal children as a control was shown in the study. A close relationship was demonstrated between the grade of the diastolic negative contrast at the distal ends of the pulmonary artery and Q p/Qs. The diastolic negative contrast effect of 2-DCE could be used as a new important index in the assessment of left-to-right ductal shunting flow. Four parameters which were closely correlated with Qp/Qs were selected from 8 parameters by the stepwise multilinear regression procedure. The 4 parameters were grade II DNCE, LVPWER, grade I DNCE, LADR. A regression equation which was capable of assessing Q p/Qs noninvasively in children with PDA was derived from the 4 parameters. The accuracy of calculation of Qp/Qs by the regression equation was 80%.

Adolescent↗
PubMed1988

The functional glycoprotein CD9 is variably acylated: localization of the variably acylated region to a membrane-associated peptide containing the binding site for the agonistic monoclonal antibody 50H.19.

Recent studies have shown that [3H]palmitic acid strongly labels both glycosylated forms (gp22 and gp24) of the signal-initiating cell surface glycoprotein CD9. We performed a two-dimensional limited proteolysis analysis with Staphylococcus aureus V8 proteinase in order to localize the palmitylation sites to final peptides on both glycosylated forms of CD9. Analysis of [3H]leucine- and [3H]amino acid mixture-labeled gp22 delineated 4 final peptides of 11, 8, 7 and 4 kDa. gp24 produced a similar pattern with the exception that the 11 kDa peptide was replaced by an N-glycosylated 13 kDa peptide. Since all four final peptides (total molecular mass of 30/32 kDa) could not be accommodated by a parent molecule of 22/24 kDa, it is likely that one of the final peptide coexists in two differently modified states. Palmitic acid labeled the 11 kDa/13 kDa final peptides, and the 7 kDa final peptide, with equal intensity, but was not incorporated into the 4 kDa final peptide, demonstrating that fatty acid is ligated in two distinct regions of the molecule. The 8 kDa final peptide was strongly labeled by [3H]palmitic acid, but only weakly by [3H]leucine. We present evidence that this peptide is derived by further acylation of the region defined by the 7 kDa peptide, and that this occurs in only 15% of the molecules. Palmitic acid is turned over faster at these additional sites, indicating that they may be more accessible to membrane transacylases. Proteolysis of CD9 on the intact cell with papain enabled the highly acylated region to be localized to a membrane-associated fragment which contains the binding site for the agonistic monoclonal antibody 50H.19. The co-localization of a functional domain with a region of variable acylation suggests that acylation events may play a role in the transduction of the signal initiated by interaction of the antibody with CD9.

Acylation↗
PubMed1988

The functional cell surface glycoprotein CD9 is distinguished by being the major fatty acid acylated and a major iodinated cell-surface component of the human platelet.

We showed that a 22 kDa protein (which comigrated with the leukocyte differentiation antigen CD9 as determined by immunoblotting with the platelet-activating mAb 50H.19) is a major iodinated component of the platelet surface. The iodinated protein was identified as CD9 by limited proteolysis analysis. The major acylated protein in platelets incubated with [3H]palmitic acid also had a mobility of 22 kDa. The radiolabelled fatty acid in CD9 appears to be ester bonded, as it is removed by treatment with hydroxylamine. Non-enzymatic ligation of the fatty acid is not involved. Since platelets lack protein synthetic capacity, the palmitolation of a surface protein indicates the existence of a plasma-membrane located transacylase which functions independently of protein synthesis. Limited proteolysis analysis of the palmitylated protein obtained by immunoprecipitation with mAb 50H.19 confirmed its identity as CD9. An additional novel minor component of 27 kDa was detected in platelets by immunoprecipitation of 125I-surface-labelled, or [3H]palmitic acid-labelled protein, and by immunoblotting with mAb 50H.19. The analogous cleavage patterns obtained by the limited proteolysis analysis of the 22, 24 and 27 kDa glycoproteins suggest that they may be differently modified variants of a single polypeptide.

Antibodies, Monoclonal↗
PubMed1987

Treatment of unstable trochanteric fractures with Dimon-Hughston osteotomy displacement fixation and acrylic cement.

For the management of unstable trochanteric fractures, a new method consisting of Dimon-Hughston medial displacement osteotomy, fixation with a sliding screw sleeve-plate device, with augmentation of the posterior and medial upper femoral cortical defect with acrylic cement, was performed in 84 patients. All patients were allowed full weight bearing on the affected extremity within 1 week of operation. Sixty-five patients were available for follow-up more than 12 months after operation. Complication rates were low and 77 per cent of the patients achieved excellent and good functional results.

Aged↗
PubMed1987

Treatment of unstable intertrochanteric fractures with Sarmiento valgus osteotomy and acrylic cement augmentation.

Seventy unstable intertrochanteric fractures (Kyle III) were treated by Sarmiento valgus osteotomy, fixation with a sliding hip-screw and plate, and augmentation of the posteromedial upper femoral defect with acrylic cement. Immediate full weight bearing walking was started after the operation. Forty-two patients were followed up for more than 1 year (average 21.4 months). Excellent or good results were obtained in 71.4 per cent. However, there was mechanical failure in which the hip screw cut out of the femoral head superolaterally in 8.6 per cent. Comparison was made between the results of the present technique and our previously reported technique which consisted of Dimon-Hughston medial displacement osteotomy, fixation with sliding hip screw and acrylic cement augmentation to the upper posteromedial femoral defect. It was found that the result of the latter technique is slightly better, probably because of the more rigid reduction.

Aged↗
PubMed1986

Reconstruction of the lateral tibial condyle by a pedicled vascularized fibular graft after en bloc resection of giant cell tumour.

Two patients with giant cell tumour of the lateral tibial condyle underwent en bloc resection and reconstruction by pedicled vascularized fibular graft. Both had good functional results and rapid solid bony union. This procedure preserved the lateral stabilizing structures of the knee, allowed relatively early mobilization and provided some cartilagionous surface for articulation with the lateral femoral condyle. The procedure was technically simple compared with homograft reconstruction, prosthetic replacement or free vascularized bone grafts, and could be performed in less sophisticated centres. The operation also provided additional bone stock for subsequent fusion if necessary.

Adult↗