Search PubMed⌕ Search

Biomedical subjects

P Han

Publications and source records attributed to P Han.

At least 91 records · Page 5Linked to original sources
PubMed1988

Altered fibrinolysis in DVT: influence of site of sampling.

Alteration of the fibrinolytic system is considered to be important in the development of deep venous thrombosis (DVT). Using specific assays for tissue plasminogen activator (t-PA) activity, t-PA inhibitor (PAI) and t-PA antigen, we measured these activities in 16 women who developed DVT during their pregnancies. A group of 24 healthy females of comparable age was studied as controls. PAI was increased in 87% of these patients compared to the healthy controls. In some of these patients a defect in release of t-PA from vascular endothelium was found as well. The site at which blood was sampled for analysis appeared to be an important criterion in the ex vivo assessment of functional t-PA reserve and PAI levels, though relatively less so for the latter measurement. The unaffected lower limbs, relative to the unaffected upper limbs, showed an increase in PAI and a demonstrable decrease in t-PA release, both representing increased risk factors for rethrombosis. The affected lower limbs showed similar but more accentuated changes in these parameters.

Adult↗
PubMed1988

Haematolytic disease due to ABO incompatibility: incidence and value of screening in an Asian population.

The population in Singapore is predominantly Asian, with Chinese forming the major ethnic group. The incidence of haemolytic disease of the newborn (HDN) due to Rh incompatibility is very low. The true incidence of HDN due to ABO incompatibility is unknown. Early discharge is practised in Singapore making it important to predict severe HDN due to ABO incompatibility as this would constitute the main cause of haemolysis next to G6PD deficiency. One thousand, six hundred and eight baby-maternal pairs were typed for ABO, Rh, and tested for direct Coombs' test, maternal titre, cord bilirubin and haptoglobin levels. Two hundred and fifty-one were found to be ABO incompatible, with 141 group A and 110 group B babies. The incidence of HDN due to ABO incompatibility was 3.7% of all group O mothers. Coombs' test, maternal antibody titre, cord bilirubin and haptoglobin levels were of low predictive value for severe HDN due to ABO incompatibility. The data further support the notion that it is not cost effective to screen for ABO incompatibility.

ABO Blood-Group System↗
PubMed1988

Direct enzyme linked antiglobulin tests (ELAT) for detecting in-vivo sensitized erythrocytes: evaluation of screening for ABO incompatibility of newborn.

ABO incompatibility of the newborn is one instance where immune hemolysis may present with a negative direct antiglobulin test (DAT) and therefore a simple sensitive test for detecting sensitization would be useful in this clinical situation. To evaluate the usefulness of ELAT in detecting in-vivo sensitized red cells, 1608 maternal-baby pairs were screened for ABO incompatibility over a period of 10 mth. Of 251 ABO-incompatible babies, there were 49 (19.5%) with positive DAT, but an additional 67 (26.7%) were ELAT positive. These were eluate positive as well, indicating that the increased number with sensitized cells as shown by ELAT is due to detection of in-vivo sensitized cells. The positive predictive value for ABO hemolytic disease of the newborn (HDN) is 48%, which is two times that of DAT. Calculating the difference of the absorbance from baseline (delta OD) may give an indication of degree of sensitization which together with the maternal antibody titre would aid us in the estimation of antigen dosage on the baby's red cells and in the appraisal of the role of antigen dosage in HDN.

ABO Blood-Group System↗
PubMed1988

Acquired factor VIIIC deficiency due to circulating factor VIIIC inhibitors.

The management of patients with Factor VIIIC inhibitor is frequently a therapeutic challenge. Treatment is often individualized. We describe 3 patients, nonhaemophilic adults, with bleeding diatheses caused by a circulating inhibitor to Factor VIIIC. One patient had long standing rheumatoid arthritis. The other two did not have any apparent underlying disease, although one of them had an antecedent antecedent phenylbutazone injection for arthralgias. Prednisolone was prescribed for two patients which resulted in rapid clinical improvement and the eventual normalization of Factor VIIIC activity. The role and rationale of immunosuppressive therapy in Factor VIIIC inhibitor is reviewed.

Adult↗
PubMed1987

Enzyme enhancement for the measurement of protein C.

Protein C measurement is now a necessary work-up of a patient with thrombosis. We described an enzyme enhancement of Laurell's immunoelectrophoresis for assay of protein C antigen. With this modification, the rockets are well defined and easily visualized and the sensitivity of the assay increased (2.5%). Samples with low protein C antigen are easily assayed.

Humans↗
PubMed1987

Wilms' tumour with acquired von Willebrand's disease.

A young infant with Wilms' tumour was found to have acquired von Willebrand's syndrome but no bleeding symptoms. Neither parent of the infant had evidence of von Willebrand's syndrome. Postoperatively, after removal of the tumour, factor VIII complex levels returned to normal. The mechanism of the acquired von Willebrand's syndrome was unclear. No evidence was found of an inhibitor of factor VIII complex or entrapment of factor VIII in the tumour.

Antigens↗
PubMed1986

Activation of chicken liver fructose- 1,6-bisphosphatase by oxidized glutathione.

Treatment of chicken liver fructose- 1,6-bisphosphatase with oxidized glutathione (GSSG) leads to an increase in activity. This activation is markedly enhanced if treatment is performed in the presence of AMP or Mn2+. The effects of AMP and Mn2+ appear to be synergistic. The maximal activation is over 13-fold and is accompanied by the disappearance of 4 sulfhydryl groups per molecule of enzyme. Both fructose 1,6-bisphosphate and fructose 2,6-bisphosphate can largely prevent this activation. Activation can be reversed by dithiothreitol or cysteine. It appears that GSSG activates this enzyme by thiol/disulfide exchanges with the enzyme's specific sulfhydryl groups.

Adenosine Monophosphate↗
PubMed1986

The noncoding region of HPV-6vc contains two distinct transcriptional enhancing elements.

HPV-6vc subgenomic fragments were inserted into an enhancer-dependent expression vector for chloramphenicol acetyltransferase (CAT) and assayed for the presence of transcriptional enhancing elements. A transcriptional enhancing element was detected in the noncoding region (NCR) of the HPV-6vc viral genome when the CAT assays were performed in viral transformed human kidney cell lines (293 and 324K), in human cervical carcinoma cell lines (HeLa and Siha), and in bovine papillomavirus type 1 (BPV-1) transformed mouse cells (C127-53). The NCR region of the HPV-6b genome was only capable of enhancing transcription of the CAT gene in the HeLa cell line at a level one-third that of the HPV-6vc NCR. The HPV-6vc NCR enhancing activity in C127-53 cells was further stimulated by the addition of sodium butyrate to the growth medium. Localization of the DNA sequences in the HPV-6vc NCR responsible for enhancing transcription revealed two distinct enhancer elements. One element (HPV-6vc position 7218-7544) was active in the 293, HeLa, Siha, and C127-53 cells. The second enhancer element (HPV-6vc position 7544-7971) was only capable of stimulating transcription in HeLa, C127-53, and Siha cells. When the HPV NCR-CAT expression vectors were cotransfected with a competitor plasmid (pNCR75) into C127-53 or HeLa cells then transcriptional enhancement decreased, indicating competition of cellular factors which affect both segments of the HPV-6vc NCR.

Acetyltransferases↗
PubMed1985

Spin label studies of the essential sulfhydryl group environment in chicken liver fructose-1,6-bisphosphatase.

The local environment of the essential sulfhydryl groups in chicken liver fructose-1,6-bisphosphatase has been investigated by ESR techniques using a series of iodoacetamide spin labels, varying in chain length between the iodoacetate and nitroxide free radical group. The ESR spectrum of spin-labeled chicken liver fructose-1,6-bisphosphatase showed that the sites of labeling were highly immunobilized when the enzyme was chemically modified by spin label iodoacetate, suggesting that the sulfhydryl groups of the protein are in a small, confined environment. From the change in the ESR spectra of these nitroxides as a function of chain length, we conclude that the sulfhydryl group is located in a cleft approx. 10.5A in depth.

Animals↗
PubMed1985

Simple procedure for removal of AMP from NADP preparation.

A simple and reliable procedure for removal of AMP from NADP preparation is described. In this procedure, a mixture of AMP and NADP solution is first incubated with 5'-nucleotidase to hydrolyze AMP to adenosine and inorganic phosphate (Pi). The reaction mixture is then applied to a Dowex 1 (formate) column. Adenosine and 5'-nucleotidase are removed by washing the column with 20 mM HCOOH. NADP is finally eluted with 3.5 M HCOOH followed by precipitation and washing with acetone. The yield of salt-free NADP is about 80%. Although Pi is coeluted with NADP in the acid form (H3PO4), it is removed during the precipitation and repeated washing with acetone. A slight modification of this procedure for simultaneous removal of AMP, ADP, and ATP from NADP preparation has also been discussed.

Adenosine Monophosphate↗