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Biomedical subjects

Z D Chen

Publications and source records attributed to Z D Chen.

At least 19 recordsLinked to original sources
PubMed2001

Effect of aging on penile ultrastructure.

AIM: To clarify whether there are anatomical changes in tunica albuginea and corpora cavemosa in aged rats. METHODS: Seventeen male Sprague-Dawley rats were divided into three groups based on age. Group A consisted of young rats (9 weeks), Group B, middle aged rats (14 weeks) and Group C, old rats (62 weeks). The penile samples were obtained and observed under a scanning electron microscope. RESULTS: The thickness (mean +/- SD) of the tunica albuginea was 0.14 +/- 0.02, 0.16 +/- 0.03 and 0.06 +/- 0.02 mm in Groups A, B and C, respectively. The tunica albuginea of group C was significantly thinner than those of the other two groups (P < 0.05) and the elastic fibers were diminished in the old rats. In the corpora cavernosa of old rats, the intracavernous pillars were irregular, in which many large collagen fibers could be observed, and the smooth muscle and elastic fibers were reduced. CONCLUSION: In old rats, the tunica albuginea became thinner with diminished elastic fibers; the collagen fibers of corpora cavernosa were increased while the smooth muscle and elastic fibers were reduced.

Aging↗
PubMed2001

[A comparison of the its sequences of the Tibetan medicine "zang yin chen"--Swertia mussotti and its adulterant species].

AIM: To identify the medicine and search for new medicine resource at the molecular level, the ITS of "Zang Yin Chen"--Swertia mussotti and its adulterant species were sequenced. METHODS: The double-stranded DNA was amplified using PCR systems 9,600 kits and sequenced on an ABI 377 automated sequencer from both directions. RESULTS: The ITS sequences of S. mussotti in different populations showed no variation. It has the unique ITS sequence and shows distinct difference from its adulterant species. In the phylogenetic tree based on the ITS data of S. mussotti and all vicarious species constructed by Paup, S. franchetiana and S. mussotti clustered together with high bootstrap support. CONCLUSION: ITS sequences can be used for the molecular authentication between the S. mussotti and its adulterant species. S. franchetiana can be regarded as a new medicine resource of "Zhang Yin Chen".

Base Sequence↗
PubMed2000

Effects of androgen and ageing on gene expression of vasoactive intestinal polypeptide in rat corpus cavernosum.

OBJECTIVE: To clarify the effects of androgens (testosterone and dihydrotestosterone, DHT) and ageing on gene expression of vasoactive intestinal polypeptide (VIP), assessed as the expression of VIP mRNA, in rat corpus cavernosum. Materials and methods The study comprised 160 male Sprague Dawley rats divided into group A (56 rats, 5 weeks old), group B (50 rats, 10 weeks old) and group C (54 rats, 58 weeks old). Groups A-C were subdivided, respectively, into subgroups 1 (intact controls), 2 (castrated), 3 (castrated but given testosterone undecanoate 25 mg/kg per month by intramuscular injection), 4 (castrated with testosterone undecanoate 50 mg/kg per month) and 5 (treated with finasteride 4.5 mg/kg per day, orally). At 4 and 10 weeks after these treatments half the rats were killed. Serum samples were taken for the measurement of total and free testosterone and DHT, using a radioimmunoassay. Penile samples (corpus cavernosum) were frozen in liquid nitrogen and stored at -80 degrees C. VIP mRNA was estimated using a semi-quantitative reverse-transcription polymerase chain reaction. RESULTS: There was no significant difference in VIP mRNA in rat corpus cavernosum between intact control and castrated subgroups, or subgroups treated with finasteride, in groups A-C, including both the 4- and 10-week old animals (P > 0.05). Penile VIP mRNA was unchanged at any dose of testosterone in the castrated subgroups in all groups (P > 0.05). There was no significant relationship between penile VIP mRNA and ageing (P > 0.05). CONCLUSIONS: The gene expression of VIP in rat corpus cavernosum is independent of androgens (testosterone and DHT) and ageing. Androgens probably induce penile erection by pathways other than VIP; ageing may have little effect on penile VIP mRNA.

Aging↗
PubMed1999

Adaptive predictive multiplicative autoregressive model for medical image compression.

In this paper, an adaptive predictive multiplicative autoregressive (APMAR) method is proposed for lossless medical image coding. The adaptive predictor is used for improving the prediction accuracy of encoded image blocks in our proposed method. Each block is first adaptively predicted by one of the seven predictors of the JPEG lossless mode and a local mean predictor. It is clear that the prediction accuracy of an adaptive predictor is better than that of a fixed predictor. Then the residual values are processed by the MAR model with Huffman coding. Comparisons with other methods [MAR, SMAR, adaptive JPEG (AJPEG)] on a series of test images show that our method is suitable for reversible medical image compression.

Angiography↗
PubMed1999

Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and paleobotany.

Phylogeny of the Betulaceae is assessed on the basis of rbcL, ITS, and morphological data. Based upon 26 rbcL sequences representing most "higher" hamamelid families, the Betulaceae are monophyletic, with Casuarinaceae as its sister group, regardless of whether the outgroup is Cunoniaceae, Cercidiphyllaceae, Hamamelidaceae, or Nothofagus. Within the Betulaceae, two sister clades are evident, corresponding to the subfamilies Betuloideae and Coryloideae. However, with only 13 phylogenetically informative sites, the rbcL sequences provide limited intra-subfamilial resolution. Internal transcribed spacer (ITS) sequences provided 96 phylogenetically informative sites from 491 aligned sites resulting in a single most parsimonious tree of 374 steps (consistency index = 0.791) with two major lineages corresponding to the two traditional subfamilies: Betuloideae (Alnus, Betula) and Coryloideae (Corylus, Ostryopsis, Carpinus, Ostrya). This arrangement is mostly consistent with those from rbcL and morphology and is greatly reinforced by analyses with the three data sets combined. In the Coryloideae, the Ostryopsis-Carpinus-Ostrya clade is well supported, with Corylus as its sister group. The sister-group relationship between Ostryopsis and the Carpinus-Ostrya clade is well supported by ITS, rbcL, and morphological data. Phylogenetic relationships among the extant genera deduced by these analyses are compatible with inferences from ecological evolution and the extensive fossil record.

Journal Article↗
PubMed1996

Functional expression of P-glycoprotein in an immortalised cell line of rat brain endothelial cells, RBE4.

The presence of P-glycoprotein in the cell plasma membrane limits the penetration of many cytotoxic substances into cells that express the gene product. There is considerable evidence also to indicate that P-glycoprotein is expressed as part of the normal blood-brain barrier in the luminal membranes of the cerebral capillary endothelial cells, where it presumably performs a protective function for the brain. This report describes the functional expression of P-glycoprotein in an immortalised cell line, RBE4, derived from rat cerebral capillary endothelial cells. The expression of P-glycoprotein is demonstrated by western immunoblotting and by immunogold and fluorescent staining with monoclonal antibodies. The cellular accumulation of [3H]colchicine and [3H]-vinblastine is investigated and shown to be enhanced by the presence of azidothymidine, chlorpromazine, verapamil, cyclosporin A, and PSC 833 ([3'-keto-Bmt1]-[Val2]-cyclosporin) at 50 or 100 microM concentration. It is concluded that the RBE4 cell line is a valuable tool for investigating the mechanisms of P-glycoprotein activity both in the blood-brain barrier and in multidrug resistance in general.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

[Study of etiology on inpatients with diarrhea in Suixian county of east Henan].

To study the etiology of inpatients with diarrhoea, 372 inpatients with diarrhoea were studied in Suixian county in 1990. Three causative agents as diarrhoeagenic bacteria, rotavirus and diarrhoeagenic parasites were isolated. 12 kinds of diarrhoeal pathogens with 237 strains were isolated. The overall isolation rate was 63.71%, including diarrhoeagenic bacteria 44.35%, rotaviruses 12.1% and diarrhoeagenic parasites 7.26%. The main pathogens were Salmonella typhimurium and Rotavirus (44.3% and 18.9% of total pathogens isolated). Inpatients with diarrhoea between 0-1 years (67.1% of total pathogens isolated) had the highest rates. The isolation rates in the third quarter and the fourth quarter were not significantly higher than that of the others seasons. Analysis on epidemiological characteristics clinical diagnosis and infectious agents was also carried out.

Adolescent↗
PubMed1993

Leiomyosarcoma of the gastric cardia: report of a case with unusual clinical manifestation.

In an uncommon presentation of gastric leiomyosarcoma, a rare malignancy of the stomach, a patient aged 63 years was admitted due to progressive exertional dyspnea. Plain film and computed tomography of the chest showed that this patient had a mediastinal neoplasm and the pulmonary function test revealed compromised pulmonary function. Operative findings revealed that this tumor arose in the esophageal-cardiac junction with mediastinal extension; the pathology report was leiomyosarcoma. The patient recovered well and the pulmonary embarrassement was relieved in the succeeding one-year period.

Cardia↗
PubMed1992

Reaction of the nucleotide analogue 2-[(4-bromo-2,3-dioxobutyl)thio]adenosine 2',5'-bisphosphate at the coenzyme site of wild-type and mutant NADP(+)-specific glutamate dehydrogenases from Salmonella typhimurium.

Wild-type glutamate dehydrogenase (EC 1.4.1.4) from Salmonella typhimurium reacts at 25 degrees C in 0.1 M phosphate buffer, pH 7, with the nucleotide analogue 2-[(4-bromo-2,3-dioxobutyl)thio]-adenosine 2',5'-bisphosphate (2-BDB-TA 2',5'-DP) to give 78% inactivation. Protection against inactivation was achieved with NADPH, indicating that modification occurred in the region of the coenzyme binding site. After reaction of the enzyme with 2-BDB-TA 2',5'-DP, the dioxo moiety of the bound reagent was reduced with [3H]NaBH4. The radioactive peptide which corresponds to the sequence Leu282-Cys283-Glu284-Ile285-Lys286 was isolated by HPLC from tryptic digests of inactive modified enzyme but was absent in digests of active enzyme modified in the presence of NADPH. Mutant enzyme E284Q was 64% inactived by 2-BDB-TA 2',5'-DP and modification of the corresponding Leu282-Lys286 peptide was found, while neither mutant enzyme C283I nor C283I:E284Q was inactivated by the nucleotide analogue and no corresponding radioactive peptides were found. These results show that cysteine-283 is the target of the reagent and is located near the coenzyme binding site. The nucleotide analogue 2-[(4-bromo-2,3-dioxobutyl)thio]-1,N6-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A 2',5'-DP) has also been shown to react with cysteine-283 (L. Haeffner-Gormley et al., 1991, J. Biol. Chem. 266, 5388-5394). However, the predominant form of the Leu282-Lys286 peptide after reaction with 2-BDB-TA 2',5'-DP contained only 0.17 mol tritium/mol leucine, whereas the 2-BDB-T epsilon A 2',5'-DP-modified peptide contained 1.80 mol tritium/mol leucine; these results indicate that the reaction product of 2-BDB-T epsilon A 2',5'-DP retains two reducible carbonyl groups while these are not available in the product of 2-BDB-TA 2',5'-DP. It is suggested that cysteine-283 reacts primarily at a carbonyl group of 2-BDB-TA 2',5'-DP to form a thiohemiacetal derivative, while it reacts at the methylene group of 2-BDB-T epsilon A 2',5'-DP with displacement of bromide. Both nucleotide analogues also yielded, in small amount, a crosslinked peptide containing the sequences 282-286 and 299-333, indicating proximity between these regions in the native structure.

Adenosine Diphosphate↗
PubMed1992

The value of adrenal autotransplantation with attached blood vessels for the treatment of Cushing's disease: a preliminary report.

We treated 5 patients with Cushing's disease by total adrenalectomy and left adrenal autotransplantation with attached blood vessels. An end-to-end vascular anastomosis was made between the adrenal central vein and the inferior epigastric artery, and the saphenous vein and adrenal middle artery were anastomosed by intussuscepting the artery into the vein in 4 patients. Steroid replacement was withdrawn 7 to 90 days after bilateral total adrenalectomy. The patients were followed for 1 to 4 years. Repeated measurement of plasma cortisol, 24-hour urinary 17-hydroxycorticosteroid and 17-ketosteroid levels in all cases was normal. As soon as the adrenal central vein and inferior epigastric artery were anastomosed part of the adrenal gland was then excised. Oozing of blood from the cut surface was retained and the adrenal gland was then embedded into the inguinal muscle in 1 patient. Small doses of steroid replacement (12.5 mg. cortisone per day) were still necessary 1 year postoperatively. The result thus indicates that this procedure is feasible and valuable for the treatment of patients with Cushing's disease and no evidence of pituitary adenoma on magnetic resonance imaging or computerized tomography.

Adrenal Glands↗
PubMed1992

[Changes in cardiac contractility induced by stimulation of hypothalamic ventromedial nucleus].

Experiments were performed on anesthetized cats to observe the effect of electrical stimulation of the hypothalamic ventromedial nucleus (VMH) on cardiac contractility as judged by the change in LVSP, dp/dtmax, Vmax, P-dp/dt, P-lndp/dt. Electrical stimulation of VMH induced an augment response in cardiac force, while stimulation of an area between VMH and the third ventricle led only to a decrease in cardiac contractile force. All these changes were not accompanied by significant changes in heart rate and unaffected by bilateral vagotomy. The present experiment indicates that the inotropic and chronotropic regulation centers of cardiac function exist in different hypothalamic areas.

Animals↗
PubMed1991

Interaction of CrATP with the phosphorylation site of the sarcoplasmic reticulum ATPase.

The chromium moiety of gamma,beta-bidentate CrATP slowly accepts a ligand from the sarcoplasmic reticulum Ca-ATPase to form an exchange inert coordination complex (k + 1 = 0.083 min-1; k - 2 = 0.003 min-1, 37 degrees C, 100 microM CaCl2). The stability of the Cr3+ coordinate bonds allowed the complex to be isolated by filtration techniques at neutral pH without acid precipitation. We found 4-5 nmol of [gamma-32P]CrATP to bind to 1 mg of sarcoplasmic reticulum protein with the subsequent occlusion of 7-8 nmol of 45Ca2+. At 37 degrees C, the CrATP.ATPase complex could be formed in the absence of Ca2+, although the reaction was 2-3 times slower than in the presence of Ca2+. Inhibition by Pi, by orthovanadate, and by fluorescein 5'-isothiocyanate verified that the bound CrATP was at the catalytic site. The site of CrATP attachment was found to be on the A tryptic fragment, possibly on the A2 subfragment. It was determined that Ca2+ binding to high affinity sites on the enzyme controls the rate by which the Cr3+ moiety accepts the ligand from the enzyme. The rate of change in the EPR spectrum of iodoacetamide spin-labeled ATPase was shown to follow the rate of ligand acceptance, rather than the binding of Ca2+ and substrate per se. This particular change has been attributed to the formation of an activated complex that is immediately precursory to phosphorylation and indicates here that this complex cannot be properly formed until the metal has been chelated by the enzyme. It is concluded that control over metal chelation (Cr3+ here, Mg2+ in the normal mechanism) is one means by which Ca2+ activates the enzyme.

Adenosine Triphosphatases↗
PubMed1991

Evaluation of cysteine 283 and glutamic acid 284 in the coenzyme binding site of Salmonella typhimurium glutamate dehydrogenase by site-directed mutagenesis and reaction with the nucleotide analogue 2-[4-bromo-2,3-dioxobutyl)thio)-1,N6-ethenoadenosine 2',5'-bisphosphate.

NADP(+)-specific glutamate dehydrogenase of Salmonella typhimurium was previously shown to react irreversibly at the coenzyme site with the nucleotide analogue 2-((4-bromo-2,3-dioxobutyl)thio)-1,N6-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A 2',5'-DP) yielding a partially active enzyme, and inactivation was attributed to modification of the peptide Leu282-Cys-Glu-Ile-Lys286 (Bansal, A., Dayton, M.A., Zalkin, H., and Colman, R.F. (1989) J. Biol. Chem. 264, 9827-9835). Three mutant enzymes have now been engineered, expressed in Escherichia coli, and purified: the single mutants C283I and E284Q and the double mutant C283I:E284Q. The wild-type and mutant enzymes have similar specific activities and Km values for alpha-ketoglutarate, ammonium ion, and NADPH, indicating that neither cysteine 283 nor glutamic acid 284 is essential for activity. The mutant enzyme E284Q, like wild-type glutamate dehydrogenase, is substantially inactivated by 2-BDB-T epsilon A 2',5'-DP. In contrast, the two cysteine mutant enzymes, C283I and C283I:E284Q, are not inactivated by 2-BDB-T epsilon A 2',5'-DP. Modified tryptic peptides with the sequence Leu-X-Glu(Gln)-Ile-Lys were isolated from wild-type or E284Q enzymes inactivated by 2-BDB-T epsilon A 2',5'-DP. This peptide was absent from digests of active wild-type enzyme modified in the presence of the protectant NADPH and from digests of active C283I enzyme after incubation with 2-BDB-T epsilon A 2',5'-DP. Although it is not required for catalytic activity, cysteine 283 is implicated by the results of the affinity labeling experiments as the reaction target of the nucleotide analogue and is located in the region of the coenzyme binding site.

Adenosine Diphosphate↗
PubMed1991

Microsurgical treatment of chyluria: a preliminary report.

We treated 80 patients with recurrent chyluria (68 men and 12 women) by a microsurgical technique since 1978. Transinguinal spermatic lymphangiovenous anastomosis was performed in 64 patients and inguinal lymph node-saphenous vein anastomosis was performed in 16. Followup was 6 months to 11 years in 50 of the former and 12 of the latter patients. Chyluria disappeared completely in 30 (60%) and 8 (66.7%) patients, respectively. In 6 of the former patients (12%) chyluria had disappeared immediately after the operation but it recurred within 1.5 to 3 years. The procedure has the advantage of a superficial operative field, and is simple and less traumatic.

Anastomosis, Surgical↗
PubMed1991

[Diagnosis and treatment of 52 cases of cardiac myxoma].

43 patients with cardiac myxoma had undergone surgical removal of the tumors under CPB 38 tumors were located in the left atrium, 5 in right atrium, and 1 in right ventricle respectively. The sites of attachment of the tumor stalk observed during operation were as follows: 34 left atrial myxomas were attached to the interatrial septum and 4 left atrial myxomas to the atrial wall. 5 right atrial myxomas were attached to the interatrial septum and 1 right ventricular myxoma to the ventricular wall. 1 patient with a right ventricular myxoma which had been removed one year ago appeared new one in the left atrium and the tumor was cut too. The diagnosis of cardiac myxoma was confirmed by 2D-echo-cardiography in all of our cases. Mitral valve replacement was done in 1 patient in this series. There was one death postoperatively. Besides these 43 cases, there were 9 patients who had not been operated upon, because of refusal of operation in 5, sudden death from cardiac arrest before operation in 2, coma from cerebral thrombosis in 1, and serious pulmonary tuberculosis in another one respectively.

Adolescent↗