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Biomedical subjects

M Wan

Publications and source records attributed to M Wan.

At least 55 records · Page 3Linked to original sources
PubMed1995

Comparison of HIV-1 protease expression in different fusion forms.

Earlier observations showed that the expression of recombinant protease of human immunodeficiency virus type-1 (HIV-1 PR) was usually in a low level, and its proteolytic activity and hydrophobicity were believed to be toxic for the host cells. Various constructs were investigated that contained an N-terminal extended HIV-1 PR gene (PR107) in order to find a system which can express this protease in high level. The constructs of PR107 gene expressed as fusion proteins either with glutathione S-transferase (GST) by pGEX-PR107 or with maltose-binding protein (MBP) by pMAL-PR107 showed that the full length of fusion protein exhibited self-cleavage in E. coli. The results from expression experiments indicated that the size of the fusion portion does not affect the self-processing of fused HIV-1 PR to release its mature form, despite the attachment of only one subunit of the dimeric protease to GST or MBP. The construct, pET-PR107, under the control of strong bacteriophage T7 promoter system, did not show clear advantages for expression of this HIV-1 PR. Comparing these three constructs, the pGEX-PR107 system showed the highest expression level. Quantitative immuno-blotting indicated that the amount of HIV-1 PR expressed by pGEX-PR107 was twice that expressed by pMAL-PR107, and thrice that expressed by pET-PR107. More than 1 mg of pure HIV-1 PR from per liter culture of E. coli. DH5 alpha containing pGEX-PR107 can be obtained via the purification procedures [Biochem. Mol. Biol. International, (1995) 35:899-912].(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-Binding Cassette Transporters↗
PubMed1995

[Tissue culture and rapid propagation of Pinellia ternata (Thunb) Breit].

In this papar, selection of the explaints and morphogenesis of the plantlet involved in the tissue culture of Pinellia ternata have been investigated, the effect of different combinations of growth-regulating substances on the morphogenesis has been studied, and the result of the establishment of clonal rapid propagation system and the transplanting of test-tube Pinellia seedlings has also been reported.

Culture Techniques↗
PubMed1993

Histologically benign or low-grade malignant tumors adjacent to high-grade ovarian carcinomas contain molecular characteristics of high-grade carcinomas.

It is presently not clear if ovarian carcinomas arise de novo or from benign precursors (cystadenomas) and if high-grade malignant tumors (carcinomas) develop from preexisting low-grade carcinomas. The presence of allelic losses on chromosome 11p15.5 distinguishes high-grade ovarian carcinomas from either low-grade carcinomas or cystadenomas. We therefore examined the distribution of such losses in different parts of heterogeneous tumors showing mixed histological grades or showing adjacent large histologically benign neoplasms. The results showed that all neoplastic areas, including those that were histologically benign or compatible with low-grade carcinomas, contained allelic losses at the above locus. This suggests that the morphologically less aggressive portions of these heterogeneous tumors were not typical cystadenomas or low-grade carcinomas and contained molecular abnormalities indicative of at least a predisposition to the high-grade carcinoma phenotype.

Alleles↗
PubMed1993

Induction of metallothionein synthesis by cadmium and zinc in cultured rabbit kidney cells (RK-13).

The effects of increasing concentrations of Zn(II) and Cd(II) on the expression of the four isometallothioneins (isoMTs), namely MT-1a, MT-2a, MT-2d and MT-2e, in rabbit kidney cells (RK-13) and the development of cellular tolerance to these metal ions were studied. The results showed that, whereas in parental cells MT concentration was low and composed nearly exclusively of MT-2a and MT-1a, all four isoMTs increased massively in abundance when the cells were exposed to toxic concentrations of Zn(II) or Cd(II), the relative increase being largest in the two minor isoforms MT-2d and MT-2e. While the response of the four isoMTs to the challenge by Zn(II) or Cd(II) was qualitatively comparable, there were differences in sensitivity and delay time, Cd(II) being the more efficient inducer and much faster in eliciting the onset of isoMT synthesis. An even larger production of isoMTs resulted when RK-13 cells were cultured in the presence of a series of metal concentrations yielding sub-lines of increased metal tolerance. In this instance too, there were marked differences in the response to Cd(II) and Zn(II). Thus, in cells of sub-lines selected for tolerance to moderate concentrations of Cd(II) the kinetic analysis of isoMT accretion gave indications of a saturable induction process while no such evidence was forthcoming for Zn(II). In sub-line cells selected for tolerance to the highest concentrations of Cd(II) or Zn(II) isoMT formation was increased by another order of magnitude, reaching for some isoforms a 100- to 1000-fold augmentation over the amounts measured in cells of the unexposed parental cells. A potentiation of this magnitude goes beyond the range of ordinary regulation of gene expression. It is to be viewed instead as an enlargement of the capacity of isoMT synthesis acquired by a variety of mechanisms in the surviving cells.

Animals↗
PubMed1993

Resolution and quantification of four metallothionein isoforms from rabbit kidney cells.

Reversed-phase high-performance liquid chromatography coupled with an on-line integrating chromatographic data system was used to separate and quantify the four major isometallothioneins MT-1a, MT-2a, MT-2d, and MT-2e present in metallothionein samples from cultured rabbit kidney cells as prepared by gel-filtration and/or ion-exchange chromatography. The standard curves for each of these isoforms showed closely comparable linear correlations between the amount of protein applied to the column and their integrated absorbance peak area at 220 nm. The lower limit of quantification is 30 pmol, sufficient to assess basal isometallothionein concentrations and to follow their variation upon metal exposure.

Animals↗
PubMed1993

Isolation of a novel fluorescent toxin from the coral reef crab, Lophozozymus pictor.

A novel toxin has been isolated from an aqueous extract of the coral reef crab Lophozozymus pictor by a combination of ion exchange and two-dimensional thin layer chromatography. The isolated toxin exhibited bioactivities similar to palytoxin (toxicity response of mice, cytotoxicity towards HeLa cells and release of potassium ions from rat erythrocytes). Unlike palytoxin it gave an intense blue fluorescence under ultraviolet light. A fluorescence scan showed that the toxin had a maximum excitation wavelength at 285 nm and a maximum emission wavelength at 355 nm. The toxin was distinguishable from palytoxin when analysed by high performance capillary electrophoresis and reverse phase high performance liquid chromatography.

Acrylamides↗
PubMed1991

[Treatment of onychomycosis with hydrazine hydrate].

The antimycotic efficacy and tolerability of hydrazine hydrate was assessed in an open study in 87 patients with onychomycosis. After six months of treatment 47% of the patients were cured, and in further 39% a marked improvement of the clinical symptoms was seen. The results show that hydrazine hydrate leads to remarkable therapeutic success in onychomycosis.

Adolescent↗
PubMed1990

Does pregnancy alter the rate of progression of diabetic nephropathy?

The effect of gestation on the rate of decline in renal function was studied in 11 pregnancies complicated by diabetic nephropathy. For each pregnancy, serum creatinine levels were available within 4 years before pregnancy, during pregnancy, and within 4 years after delivery. Although all of these patients were hypertensive and had increased proteinuria during pregnancy, the mean serum creatinine just prior to conception (1.3 +/- 0.5 mg/dl) and the last follow-up value (1.2 +/- 0.3 mg/dl) were not significantly different. When the inverse of serum creatinine (1/Scr) was used to estimate creatinine clearance, the renal function was either improved or remained stable in the majority of the pregnancies (7 of 11). The observed decline in renal function through the end of follow-up appeared to be consistent with the expected natural course of diabetic nephropathy in the absence of pregnancy. Furthermore, the slope for inverse serum creatinine before and after pregnancy was not significantly different. In conclusion, pregnancy in patients with mild to moderate diabetic nephropathy does not seem to accelerate the rate of decline in renal function.

Adult↗
PubMed1990

Differentiation of monochorionic and dichorionic twin placentas by antenatal ultrasonic evaluation.

The prenatal identification of various types of placentation is important for the antenatal management of twin pregnancies. Such classification can be achieved with the use of ultrasound examination. In 32 cases of twin pregnancy the intervening septum was classified as either a thick (dichorionic) or thin (monochorionic) type. Macroscopic and microscopic examination of the placenta after delivery confirmed the ultrasound diagnosis in 24 of the 30 cases, an accuracy of 80%.

Cardiotocography↗
PubMed1990

A case of hemolytic disease of the newborn caused by anti-Hro and anti-e.

A Chinese woman of blood group B, D- and her husband of blood group AB, CCDee were examined. The woman had not been transfused before. Their first two babies died. Anti-Hro and anti-e were found in the mother's serum. During her third pregnancy, the titer of antibodies went up quickly, approximately one titer per month. After 36 weeks of pregnancy, the baby was delivered by Caesarean section. The cord blood Hb was 88 g/L, his red blood cell count 2.7 x 10(12)/L, and total bilirubin 114.6 mol/L. The baby was of blood group AB, and CDe-D-genotype. Exchange transfusion was begun 2.5 hours after birth. O, ccDEE washed red cells together with group AB plasma were used. Two days later, 70 ml washed O, ccDEE concentrated red cells were administered. The baby is alive and in good health.

Erythroblastosis, Fetal↗
PubMed1989

Diagnosis of intra-amniotic infection: the acridine orange stain.

The rapid diagnosis of intra-amniotic infection in patients with premature rupture of the membranes (PROM) and preterm labor is of utmost importance. The Gram's stain examination of amniotic fluid can only detect half of these infections. The acridine orange (AO) stain has been claimed to be superior to the Gram's stain in the detection of bacteria in biologic fluids. Therefore, we undertook the present study to examine the value of AO in the detection of bacteria in amniotic fluid. One hundred and thirty-eight patients with a culture-documented prevalence of intra-amniotic infection of 23.2% were studied. The diagnostic indices of the AO were: sensitivity, 43.8%, specificity, 97.2%, positive predictive value, 82.8%, and negative predictive value, 85.1%; the diagnostic indices for the Gram's stain were: sensitivity, 46.8%, specificity, 98.1%, positive predictive value, 88.2%, and negative predictive value, 85.9%. There was no difference in the diagnostic values of the tests. The agreement between the two techniques was substantial, as indicated by a kappa index of 0.72 (SE = 0.17, p less than 0.001). The AO offered no significant advantage over the Gram's stain examination of amniotic fluid in the detection of intra-amniotic infection. However, the AO stain was able to identify mycoplasma infections that escaped detection by the Gram's stain. Therefore, the AO is presently the only microscopic technique capable of detecting mycoplasma in amniotic fluid.

Acridine Orange↗
PubMed1989

[Extraction of effective parts of Alternanthera philoxeroides (Mart.) Griseb. and its antiviral effect].

Several parts of Alternanthera philoxeroides were extracted by lead-salt sedimentation and double phase solvent extractive technique and their antiviral effects were studied. The results showed that extracts of petroleum ether, ether, and ethyl acetate have inhibitory effect on epidemic hemorrhagic fever virus (EHFV). The antiviral effective part is coumarin analogue.

Antiviral Agents↗
PubMed1988

Labor and infection. II. Bacterial endotoxin in amniotic fluid and its relationship to the onset of preterm labor.

We have previously reported the detection of endotoxin in the amniotic fluid of patients with gram-negative intraamniotic infection. Endotoxin or lipopolysaccharide is a potent biologic product capable of inducing prostaglandin release from several cell types and, therefore, may be involved in the onset of human parturition in the presence of intraamniotic infection. This article describes a technique for the quantification of endotoxin in amniotic fluid. The method uses a computer-assisted quantification of the turbidimetric reaction between the Limulus amebocyte lysate and endotoxin. Serial dilutions of Escherichia coli endotoxin in culture-negative amniotic fluid were prepared, and the samples were run in the assay. Amniotic fluid was found to enhance the reaction, and a dilution of 1:20 was required for this biologic fluid to behave similarly to pyrogen-free water. The sensitivity of this kinetic turbidimetric technique in the detection of endotoxin in amniotic fluid was 40 pg/ml. This method was applied to the quantification of endotoxin concentration in amniotic fluid in 26 patients with intraamniotic infection and premature rupture of membranes. Patients in active labor had higher concentrations of endotoxin (median = 47,514 pg/ml) than nonlaboring patients (median = 635 pg/ml) (p less than 0.025). Therefore, women with preterm labor had a higher median concentration of endotoxin in amniotic fluid than patients who were not in labor.

Amniotic Fluid↗
PubMed1988

The value and limitations of the Gram stain examination in the diagnosis of intraamniotic infection.

Gram stain examination of amniotic fluid is a method used for the rapid diagnosis of intraamniotic infection in patients with preterm premature rupture of membranes and preterm labor. The management of these patients relies heavily on the Gram stain results. Therefore, it is critical that the diagnostic value and limitations, optimal technique, and outcome correlates be precisely established. Most studies have focused on culture results rather than on Gram stain results to describe neonatal and maternal outcome. However, management is based on the Gram stain because culture results are not immediately available. One hundred eighty-seven amniocenteses were performed in 131 patients with preterm premature rupture of the membranes (n = 90) and preterm labor (n = 41). Spun and unspun Gram stains were performed. Centrifugation of the sample did not improve the sensitivity of the technique significantly. The agreement between the two methods was substantial (kappa index 0.89, p less than 0.001). The sensitivity of the Gram stain was 44.8% and the specificity was 97.6%. The sensitivity of the Gram stain was directly proportional to the number of bacteria present in amniotic fluid. In the presence of greater than 10(5) colony forming units per milliliter, 80% of the Gram stains were positive. The absence of both bacteria and white blood cells in a smear was associated with a negative culture of amniotic fluid in 95% of the cases. Clinical chorioamnionitis was associated with a positive Gram stain of amniotic fluid (p less than 0.001). There was a trend toward a higher incidence of endometritis in patients with a positive Gram stain compared with those with a negative Gram stain (p = 0.07). There was no neonatal infectious morbidity in patients with a true negative Gram stain. Patients with a false negative Gram stain had a 25% incidence of neonatal infectious complications (proved and suspected sepsis).

Adult↗
PubMed1988

Fetal body and breathing movements as predictors of intraamniotic infection in preterm premature rupture of membranes.

A prospective study of fetal behavior in cases complicated with preterm premature rupture of membranes was conducted in 41 patients. The length of time and the number of fetal breathing and gross body movements were correlated with the amniotic fluid culture results. An episode of fetal activity (body movements and breathing movements) of greater than or equal to 30 seconds during 30 minutes of observation was associated with the absence of intraamniotic infection in 100% of the cases. On the other hand, the absence of fetal breathing movements and gross body movements of less than a 50 second duration during 30 minutes of observation was associated with positive amniotic fluid cultures in all cases. If an episode of fetal breathing movements was present but lasted less than 30 seconds and/or the total time of gross body movements was greater than 50 seconds, 64% of patients had an intraamniotic infection.

Amniocentesis↗
PubMed1988

The value of the leukocyte esterase test in diagnosing intra-amniotic infection.

This communication examines the diagnostic value of the leukocyte esterase activity (LEA) test in the detection of intra-amniotic infection. Amniotic fluid from 171 consecutive patients with premature rupture of membranes (n = 149) and preterm labor (n = 22) was obtained through amniocentesis. Gram stain, bacterial and mycoplasma cultures, and LEA tests were performed. The LEA had a sensitivity of 19%, a specificity of 86.7%, a positive predictive value (PPV) of 42.3% and a negative predictive value (NPV) of 67.6% in the prediction of a positive amniotic fluid culture (prevalence of positive cultures = 33.9%). The Gram stain had a sensitivity of 36.2%, specificity of 94.7%, PPV of 77.8%, and NPV of 74.3%. When both tests were combined, a significant increase in sensitivity to 50% was observed. This was associated with a drop in specificity to 81.4%. There was a correlation between the number of white blood cells in the amniotic fluid and the result of the LEA test. A positive LEA assay was associated with an increased likelihood of postpartum endometritis, but not with clinical chorioamnionitis or neonatal infectious morbidity.

Amniocentesis↗
PubMed1988

Listeria monocytogenes chorioamnionitis and preterm labor.

Two cases of Listeria monocytogenes chorioamnionitis in association with preterm labor are presented. The pathogenicity and the recommended treatments of listeriosis in regard to the pregnancy outcomes of our patients are discussed.

Adult↗