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Biomedical subjects

S Z Chen

Publications and source records attributed to S Z Chen.

At least 19 recordsLinked to original sources
PubMed1992

[Variation of WGA and PNA binding glycoproteins in early pregnant rabbit uterine fluid].

The qualitative and quantitative changes of two kinds of lectin (WGA, PNA) binding glycoproteins in early pregnant rabbit uterine fluid (D4-D12) were measured by Western blot and Video densitometer scanning methods. During peri-implantation stage (D6, D7 and D9), there are two WGA binding glycoproteins with MW about 42 kd, 28 kd and a PNA binding glycoprotein with MW 75 kd. It is suggested that the three proteins are stage-specific glycoproteins in rabbit uterine fluid in the course of implantation.

Animals↗
PubMed1992

[The expression of MG7 corresponding antigen in gastrointestinal polyps and its relation with cancer].

We studied 112 patients with polyps of the stomach, gallbladder and colorectum by immunohistochemical staining with monoclonal antibody (MG7) against gastric cancer and avidin-biotin complex (ABC) technique. The positive expression of the MG7-corresponding antigen (MG7-Ag) was 100%, 100%, and 60.0% respectively in villous, mixed and tubular polyps. A close correlation was shown between dysplasia of grade II and the positive expression of MG7-Ag (p < 0.05). The positive expression was significantly related to canceration (P < 0.025). No malignancy was found in 45 patients with negative expression. But 12 of 67 patients with positive expression developed cancers in 3 to 38 months. The patients with positive expression of MG7-Ag were high risk group developing cancer.

Adenosine Triphosphate↗
PubMed1992

Variations of lectin-binding glycoproteins in early pregnant rabbit embryo.

In the present study, the quantitative and qualitative changes of three kinds of lectin-binding glycoproteins of early pregnant rabbit embryos (D4-D12) were analyzed. The technique of Western blot, as well as video densitometer scanning and its analytic software was used for analysis. Results found that there were five specific lectin-binding glycoproteins in Day 4 to Day 6 blastocyst fluids: one ConA-binding glycoprotein about 70 kD, two WGA-binding glycoproteins respectively about 42 kD and 25 kD and two PNA-binding glycoprotein respectively about 180 kD and 75 kD. They disappeared immediately after implantation. It is demonstrated that there are stage-specific glycoproteins in rabbit blastocyst fluid which might be relevant to the recognition of pregnancy and implantation.

Animals↗
PubMed1991

Crystallization and chemical modification of disulfide bond of calf chymosin.

In order to carry out protein engineering of chymosin, purification, crystallization and chemical modification of calf chymosin were undertaken. The resolution of iso-enzymes A,B and the degraded product, fraction C was improved and the period of purification was shortened by using fast protein liquid chromatograph (FPLC). Crystal of approximately cubic shape was obtained from 10 mg/ml purified chymosin B at 4 degrees C after successive dialysis against 1.4, 1.8 and 2.0 M NaCl in 0.1 M sodium phosphate buffer. One disulfide bond located on the surface of chymosin molecule was reduced by 0.72 mM dithiothreitol (DTT) at pH 6.3. The reduced disulfide bond was identified as Cys250-Cys283 by using the method of cyanogen bromide cleavage and peptide separation. The reduction of one disulfide bond resulted in the loss of about 25% activity. Carboxymethylated and mercurated derivatives exhibit the similar activity to that of the reduced enzyme suggesting that Cys250-Cys283 plays some role in keeping the conformation with full activity.

Animals↗
PubMed1991

[Re-establishment of sensory function of flaps by nerve implantation].

Taking the afferent sensory fiber discharges as an indicator, re-establishment of sensation of the abdominal island flap was investigated in rabbits. The flap, being fed by the superficial epigastric artery, was transplanted to the leg, and the saphenous nerve was implanted into it. The restoration of flap sensation was studied neuroelectrophysiologically. It was shown that nerve fiber discharges were detected within the boundary of the flaps, and mainly in the central portion of the flap along the course of the implanted nerve, in the nerve implantation animals. There was definite evidence of re-establishment of tactile, pressure, pain and temperature sensations in the flap, except that the unit discharges evoked by lower threshold stimulation were less than normal. In the flaps without nerve implantation nerve fiber discharge was rare, and pain and temperature sensation discharges could not be recorded. In 8 patients, nerve implantation was done in an attempt to re-establish sensations in the fingers. Altogether, 11 lateral antebrachial cutaneous nerve grafts were implanted to 10 fingers. The longest nerve graft was 9cm, and the shortest 2.5cm. They were implanted under the dermis of the denervated palmar skin of fingers or flaps. The follow-up time was 97-924 days. The results were very satisfactory.

Adolescent↗
PubMed1991

[Detection of Plasmodium falciparum infection in humans by (Dig)-DNA probe].

In this study, we used Digoxigenin, (Dig)-11-dUTP, in the Genius kit purchased from Boehringer Mannheim to label the Plasmodium falciparum (P.f.) DNA fragment by random primed labelling method. The P. falciparum DNA fragment was isolated from the recombinant clone pPF14 by enzyme digestion and agarose electrophoresis. This probe is designated pPF14-F-Dig. Purified P.f. DNA and blood samples from malaria patients in Hainan Province of China were detected by the probe in dot-blot hybridization. Thirty-eight patients with falciparum malaria, three with falciparum malaria and vivax malaria and four with vivax malaria were detected with the pPF14-F-Dig probe. The results showed that the pPF14-F-Dig probe could detect at least 40 pg of P.f. DNA and a parasitemia of 0.005 percent. Out of 38 detected P.f. patients' blood samples, 33 hybridized positively with this probe. The positivity rate was 86.8%. Twenty-one normal blood samples all showed negative. In addition, 2 of 3 samples with P.f. and P.v. were positive. Three of 4 samples with P.v. were negative and one was doubtful. The preliminary result of this study indicates that the pPF14-F-Dig probe could detect the patients of falciparum malaria with good sensitivity and specificity, and that this probe can be used to detect the patients with P. falciparum in Hainan Province.

Animals↗
PubMed1990

Crystals of alpha-momorcharin. A new ribosome-inactivating protein.

Crystals of alpha-momorcharin were obtained by vapour phase diffusion. The crystal belongs to the space group R3, with unit cell constants a = b = 131.3 A, c = 39.5 A. There is one alpha-momorcharin molecule in the asymmetric unit; a data set at 3 A has been collected.

Crystallization↗
PubMed1990

Resurfacing difficult wounds: selective use of the posterior tibial flap.

The posterior tibial flap is a type C fasciocutaneous flap from the medial calf with the posterior tibial vascular bundle as its pedicle. Most of the skin perforators, 1 to 3 in number, can be found in the middle third of the leg, with an average diameter of 0.8 mm and an average length of 22 mm. The posterior tibial artery ranges between 1.5 and 2.0 mm in diameter, although it is absent in 8 percent of limbs. Since the saphenous nerve is taken with the flap, this is an innervated flap. The flap can be transferred as a free flap or a pedicled flap. The reversed-flow pedicled flap has an average pedicle length of 8 cm. The posterior tibial flap is a reliable, large, thin, innervated flap and can be raised with the patient supine. Case reports are presented of six patients who received a free flap transfer and of one patient who received a reversed-flow pedicled flap. There were two cases of heel ulcerations, two crushed hands, one chronic ulceration and osteomyelitis of the tibia, one burn contracture of the neck, and one salvage flap for diabetic gangrene of the hand.

Adult↗
PubMed1989

Toxicity of vincristine overdose in a patient with invasive mole.

A few reports have documented overdoses of vincristine sulfate. The present report describes our experience with serious complications of a vincristine overdose in an 18-year-old female who had methotrexate-resistant invasive mole. The patient received VAC therapy as the second line chemotherapy after 2 courses of MTX therapy. In the 6th course of VAC therapy, she was given 5 consecutive daily doses of VCR by mistake. On the 5th day of this VAC therapy, she showed the following toxic symptoms: abdominal pain, lumbago, insomnia, bleeding tendency, absence of motor reflex, leukopenia, and paralytic ileus. These symptoms led to realization of the VCR overdose. Leucovorin calcium administration and supportive treatment were carried out. Although it was difficult to evaluate the efficacy of leucovorin calcium on the vincristine toxic symptoms, she recovered and was discharged on the 36th hospital day.

Adolescent↗
PubMed1989

Skin fibroblasts from individuals hemizygous for the familial adenopolyposis susceptibility gene show delayed crisis in vitro.

Normal human fibroblast cells have not been reported to escape crisis--that is, they die after about 24 doublings in culture. We have been studying the growth properties of skin fibroblast cells from persons in families with familial adenopolyposis of the colon (FAP). An individual hemizygous at the FAP locus will develop hyperplasia of the colonic epithelium followed by colonic polyps, both at an early age. Polyps themselves still retain a single functional FAP allele. A mutation or deletion in this allele in a polyp is hypothesized to lead to further loss of growth control; thus, a tumor is formed. We found that the in vitro life-span of skin fibroblast cells from FAP individuals and from some asymptomatic children were markedly extended when compared with normal individuals.

Adenomatous Polyposis Coli↗
PubMed1989

Limitation of the alpha-methylnorepinephrine hypothesis in the hypotensive effect of alpha-methyldopa.

To test the hypothesis that alpha-methylnorepinephrine (MNE) is the principal active metabolite involved in the hypotensive action of alpha-methyldopa (MD), we determined the relationship between MD's depressor response and tissue levels of MD metabolites in critical sites. After administration of 250 mg/kg MD intraperitoneally to Sprague-Dawley rats (300 +/- 50 g), we studied both heart (left ventricle) and brainstem MD, MNE and endogenous NE levels using HPLC with electrochemical detection. We also measured systolic blood pressure before and during MD (25-250 mg/kg i.p.) treatment using the tail-cuff method. Our results indicate that: (1) peak MD hypotensive response was dose-dependent. (2) Central NE concentration was maximally reduced by 2 hours whereas peripheral NE was maximally reduced by 18 hours. The maximal hypotensive effect was closer to the central peak distribution of MNE than MD. (3) The MD concentrations and NE concentrations in brainstem and heart showed counterclockwise hysteresis while MNE showed clockwise hysteresis. Furthermore, the area of MNE hysteresis in brainstem was larger than that of NE. We conclude that MD's depressor effect can not be completely explained by the assumption that MNE is the sole active metabolite; alternate metabolites or mechanisms would appear to be operative.

Animals↗
PubMed1988

Cloning type-II restriction and modification genes.

We have cloned into Escherichia coli the genes for 38 type-II bacterial modification methyltransferases. The clones were isolated by selecting in vitro for protectively modified recombinants. Most of the clones modify their DNA fully but a substantial number modify only partially. In approximately one-half of the clones, the genes for the corresponding endonucleases are also present. Some of these clones restrict infecting phages and others do not. Clones carrying endonuclease genes but lacking methyltransferase genes have been found, in several instances, to be viable.

Bacterial Proteins↗