Modification of catalytic properties of chicken liver fructose 1,6-bisphosphatase by allicin

The activity of chicken liver fructose 1,6-bisphosphatase increases dramatically after incubation with allicin, a major biologically active compound produced by garlic. Activation is more pronounced when the enzyme is assayed with Mn2+ than Mg2+. Maximum activation is accompanied by the disappearance of 4 highly reactive sulfhydryl groups per molecule of enzyme. This modification also leads to loss of activation by K+, and reduced sensitivity to inhibition by AMP, fructose 2,6-bisphosphate, and high concentration of fructose 1,6-bisphosphate. All the altered properties induced by allicin can be reversed by dithiothreitol or tris(2-carboxyethyl)phosphine, the latter being much more effective.

Serum ferritin measurement and the degree of agreement using four techniques

Four commercial assay kits to measure serum ferritin were compared to establish the degree of agreement and interchangeability between the different techniques based on the intraclass correlation coefficient (ri). Radioimmunoassay, microparticle enzyme immunoassay, enzyme-linked immunosorbent assay, and chemiluminescent immunoassay systems were used. The Pearson product-moment correlation factor (r) between any two methods was at least 0.98, and the intercept of the regression equations ranged from -0.613 to 3.797, indicating that the methods were comparable. Furthermore, the intraclass correlation coefficient (ri) was at least 0.98, suggesting that the methods were interchangeable.

Mechanism of action of the papillomavirus E2 repressor: repression in the absence of DNA binding

Repression of papillomavirus E2-dependent gene expression was studied by using transient transfections into mouse embryo fibroblast cells. Cotransfection of a gene corresponding to the naturally occurring repressor E2-TR along with the full-length E2 gene resulted in up to 98% repression of E2-dependent reporter gene expression. A series of E2 DNA-binding domain mutants were transferred into the E2-TR form and characterized for their ability to repress E2-dependent transactivation. All mutants which were defective for DNA binding but were dimerization competent repressed E2 transactivation as well or nearly as well as the wild-type repressor. E2 mutants which lacked dimerization activity repressed transactivation poorly or not at all. These results indicate that the E2 repressor can inhibit transcription, in the absence of DNA binding, by forming heterodimers with full-length E2.

Thrombospondin and other possible related matrix proteins in malignant and benign breast disease. An immunohistochemical study

Thrombospondin (TSP), which plays an important hemostatic role, is a 450-kd cytoadhesive protein present in the alpha granules of platelets. In vitro experiments using cultured malignant cells suggest that it may help to mediate malignant cell attachment to extracellular matrix and may be important in cancer invasiveness. The authors studied a group of malignant and benign breast tissues for the expression of TSP and provide evidence that TSP may have a role in tumor invasiveness. Using immunohistochemical techniques, the authors found in 48 fresh specimens of breast carcinoma that TSP stained strongly in the desmoplastic stroma or at the basement membrane associated with the malignant ductal epithelium. Tumor cells abutting these tissues revealed cytoplasmic staining for TSP. Stronger TSP staining was seen in the poorly differentiated tumors. These findings were compared with those of normal and benign breast tissue, which showed no TSP staining apart from reactivity in the large distended cysts of fibrocystic disease and faint staining in the stroma of fibroadenomas. Staining for integrin was positive in lymphocytes of both malignant and benign breast disease and equivocally also in the stromal cells of the breast cancer tissue. Immunoreactivity to TSP in tissues was also compared with that of fibronectin, laminin, and collagen type I, III, and IV. The overall findings suggest that thrombospondin may have a role in the tumor biology of invasiveness.

Tissue expansion as an alternative to skin grafting for closure of skin deficits

Recent advances in the technical aspects of tissue expanders for closure of skin deficits have led to an overall reduction in the high rate of complications typically associated with their usage. The authors provide a review of the recent refinements in the technique of the tissue expansion process. A discussion of current and future applications using this technique in the treatment of various lower extremity pathologies, including clubfoot, is presented. A case report on the use of a subcutaneous tissue expander for the treatment of a failed skin graft of the medial ankle is included.

Evidence for heat-stable liver cytosol substance(s) capable of causing oxidative activation of fructose 1,6-bisphosphatase

The endogenous fructose 1,6-bisphosphatase (FBPase) in chicken liver extract undergoes a drastic increase in activity if the pH of the extract is in the alkaline range. Greater and more consistent activation occurs when purified FBPase, placed inside dialysis sack, is incubated in liver extract. Maximal activation (over 16-fold) is accompanied by the disappearance of 4 highly reactive sulfhydryl groups (SH) per molecule of enzyme. The activating effect of the extract remains essentially unchanged after heating to 100 degrees C. Activation can be reversed by dithiothreitol. These data show the existence in liver cytosol of heat-stable substance(s) capable of activating FBPase presumably by forming disulfide bonds with the enzyme's highly reactive SH groups.

Transactivation of heterologous promoters by HIV-1 tat

To determine whether HIV-1 tat can transactivate a heterologous promoter lacking HIV sequences other than the TAR element, TAR was placed downstream of the chicken beta-actin promoter. Tat increased expression directed by the actin-TAR promoter to a degree equal to tat induction of the HIV-1 LTR. Optimal transactivation was observed when TAR was positioned downstream of the actin promoter such that the expected cap site of transcripts from this promoter would be the same as in transcripts directed by the HIV-1 LTR. Tat was able to transactivate, though to a lesser extent, a promoter consisting solely of a TATA element fused to TAR. Thus, tat induction does not require HIV-1 LTR promoter sequences other than TAR. Tat, when fused to the DNA binding domain of BPV-1 E2, was able to transactivate a truncated SV40 promoter containing upstream E2 binding sites, indicating that tat may be capable of transactivation when directed by a DNA binding protein to an upstream site in a heterologous promoter lacking all HIV sequences. Substitution of Ala for Lys at position 41 of tat in the tat-E2 fusion, a mutation which dramatically decreases tat transactivation of the HIV-1 LTR, eliminated this transactivation.

Erythropoietin levels and inhibition of erythropoiesis in end-stage renal failure

Anaemia of chronic renal failure is multifactorial. Twenty-one patients with end-stage renal disease (ESRD) and 21 normal subjects were studied to determine the significance of serum erythropoietin levels and erythropoiesis inhibition in the aetiology of renal anaemia. Serum erythropoietin levels and erythropoiesis inhibition were measured by determining the incorporation of labelled-thymidine into the DNA of rabbit bone marrow cells. The mean haemoglobin concentration was 9.0 +/- 0.5 g/dl (mean +/- SEM) in ESRD and 14.4 +/- 0.4 g/dl in normal controls. Serum erythropoietin levels (99.9 +/- 17.9 mU/ml in ESRD vs 74.9 +/- 9.7 mU/ml in normal controls) and inhibition of erythropoiesis (252 +/- 28.9 in ESRD vs 186.2 +/- 19.4 in normal controls) were not significantly different in both groups. However, erythropoiesis inhibition had a significant correlation with the degree of anaemia (p less than 0.01). The results suggest that erythropoiesis inhibition play a significant role in the pathogenesis of renal anaemia.

Lymphocyte changes in secondary dengue fever: use of the Technicon H*1 to monitor progress of infection

Secondary dengue fever as dengue hemorrhagic fever or dengue shock syndrome is a potentially fatal complication of an infection that presents with few clinical signs that help in the diagnosis. Previous workers have reported the value of buffy coat determinations of atypical lymphocytes as an aid to the diagnosis. We report here the use of an automated white blood cell differential counter, the Technicon H*1 in the monitoring of the atypical lymphocyte count as a measure of the progress of the infection in a retrospective study of serial full blood counts in 45 serologically confirmed patients. Technicon H*1 'basophil' and large unstained cell counts and manual atypical lymphocyte counts rose in tandem with the drop in platelets and decreased when the platelets recovered. In a sub-study, the atypical lymphocytes were immunophenotyped and found to be predominantly derived from T lymphocytes. We conclude that the Technicon H*1 is a useful monitor of the activity of the infection in dengue hemorrhagic fever.

Immunophenotypic characterisation of monocytoid differentiation markers in acute non-lymphoblastic leukaemias

The FAB classification of acute non-lymphoblastic leukaemias has been shown to have some clinical use in the prognostication of patient survival. ANLL with monocytoid features (M4, M5) fare worse than those which are predominantly myeloblastic (M1, M2). Classification is, however, sometimes difficult if non-specific esterase activity is not strongly expressed. Monoclonal antibody characterisation of myeloid differentiation antigens may be of some use as a supplementary aid. We immunophenotyped the blast cells from 26 cases for HLA-Dr, CD14 (Mo2, My4), CD13 (My17) and CD33 (My9) expression using the APAAP method. A combination of CD14 and CD33 used together was useful in differentiating myeloblastic from monocytoid acute non-lymphoblastic leukaemias. We conclude that the use of surface markers is a useful adjunct to the diagnostic means presently available.

Lack of agreement of chromogenic and clotting assays for factor X and protein C in warfarinised plasma

Coagulation serine proteases can be measured with either a chromogenic substrate assay or a clotting assay using deficient plasmas. It is a concern whether both assays give similar quantitative results, in particular in plasma obtained from patients on long term warfarin therapy. If these two assay methods were interchangeable, then the chromogenic substrate assay has the advantages of precision as well as laboratory automation. We used the intraclass correlation coefficient (rI) to assess the agreement between the two methods in measuring factor X and protein C levels in warfarinised plasma. The results indicate that the extent and pattern of agreement of the two methods for the measurement of the two variables in warfarinised plasma are poor, despite high Pearson product moment coefficients of correlation.

Cytogenetic analysis in myeloid malignancies

Forty-one patients with myeloid malignancies, majority newly diagnosed and previously untreated, were systematically karyotyped between January 1988 and December 1989 using fluorodeoxyuridine (FdU) synchronisation and Giemsa banding techniques. Eighteen patients had acute myeloid leukaemia (AML), 13 had one form or other of a myeloproliferative disorder and 10 fulfilled the clinical and morphological criteria for the myelodysplastic syndrome (MDS). Ten AML patients had cytogenetic abnormalities. All 6 chronic myeloid leukaemia (CML) patients carried the Philadelphia chromosome with 2 having additional abnormal clones. Only four MDS patients showed involvement of either chromosome 5 or 7.

Chemotherapy of adult acute myeloid leukaemia

Great strides have been made in the chemotherapy of adult acute myeloid leukaemia in the last two decades. This paper describes our experience in the treatment of adult acute myeloid leukaemia from 1980-88. About two thirds of patients achieve remission with a standard chemotherapy protocol. Early disease relapse and measures to prevent it are major problems. The majority of patients with adult myeloid leukaemia, presently, are not cured with chemotherapy alone.

Diagnosis of leukocyte disorders with an automated haematology counter (Technicon H-1 analyser)

The differential leukocyte count is very important in the diagnosis of various leukocyte disorders. Newer automated haematology counters can now perform differential leukocyte count, thus reducing the dependence on experienced medical technologists. The Technicon H.1 analyser (Technicon Instruments Corp., New York, USA) can perform even more complicated tasks like flagging abnormal cells, generating cytograms based on cell size and cytochemistry. In this paper we report on the useful cellular characteristics of the various leukocyte disorders as measured by the Technicon H.1 analyser.

Hereditary protein C deficiency--the first symptomatic family in Singapore

Protein C is an important physiological inhibitor of coagulation. A deficiency of this protein is a recognised cause of recurrent venous thromboembolism. The assay for protein C was not locally available until recently. Our investigation of a young Malay woman who had sustained two previous pulmonary emboli led us to identify the first family in Singapore with this familial disorder. The definitive diagnosis of symptomatic protein C deficiency justifies longterm anticoagulant therapy in two members of this family. We now systematically screen all young adults who present with the first episode of deep venous thrombosis or pulmonary embolism irrespective of whether the event is spontaneous or seemingly precipitated.

Modulation of hepatic glucose-6-phosphate dehydrogenase activity in male and female rats by estrogen

The effect of estradiol-17 beta on the activity of glucose-6-phosphate dehydrogenase was studied in both male and female rats to further characterize the sex differences in the activity of this enzyme. Four groups of intact and castrated rats were implanted subcutaneously with graded doses (2.4, 4.8 and 7.2 micrograms/day) of pelleted estradiol in a physiologically relevant experimental system. After fourteen days the rats were sacrificed and their livers were assayed for G6PD activities. The result indicated that: (i) the enzyme activity was 3-fold higher in normal adult female than in male rats, (ii) low doses of E2 (2.4, 4.8 and 7.2 micrograms/day) increased the activity of G6PD 6-fold in castrated males and over 2-fold in female castrates as well as intact rats (iii) E2 stimulation of G6PD activity appears to be more effective in castrated males than in female rats (IV) sex difference in the activity of G6PD disappeared after treatment with E2 in castrated rats. It is concluded that the activity of G6PD in rats is markedly enhanced by low doses of E2, which appears to be largely responsible for the sex differences in the activity of this enzyme in rats.

Quantitation of red cell-bound immunoglobulin and complement using enzyme-linked antiglobulin consumption assay

Various techniques have been described for quantitating IgG or complement (C3) on red cells (RBCs). The techniques either are cumbersome, as the complement consumption test, or use radioactivity. This paper describes an antiglobulin consumption assay using an enzyme-linked immunosorbent method that can be used to quantitate IgG, IgM, and C3. With this technique RBCs from normal, healthy donors gave a mean value of 106 +/- 60 molecules of IgG per RBC, 4.5 +/- 3 molecules of IgM per RBC, and 37 +/- 28 molecules of C3 per RBC, respectively. The RBCs of hospital patients, particularly of those with infections or inflammatory conditions, contain increased amounts of nonspecifically bound immunoproteins. The availability of a common method to quantitate RBC-associated IgG, IgM, and C3 allows easy monitoring or study of the immune mechanism of autoimmune hemolytic anemia.

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.

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.

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.

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.

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.

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.