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Biomedical subjects

Z H Yu

Publications and source records attributed to Z H Yu.

At least 19 recordsLinked to original sources
PubMed2001

A stable glucose biosensor prepared by co-immobilizing glucose oxidase into poly(p-chlorophenol) at a platinum electrode.

An amperometric glucose biosensor was successfully developed by electrochemical polymerization of p-chlorophenol (4-CP) at a Pt electrode in the presence of glucose oxidase. The amperometric response of this biosensor to hydrogen peroxide, formed as the product of enzymatic reaction, was measured at a potential of 0.6 V (vs. SCE) in phosphate buffer solution. The performances of sensors, prepared at different monomer concentrations and polymerization potentials, were investigated in detail. The biosensor prepared under optimal conditions had a linear response to glucose ranging from 2.5 x 10(-4) to 1.5 x 10(-2) mol L(-1) with a correlation coefficient of 0.997 and a response time of less than 2 s. Substrate selectivity of the polymer-based enzyme electrode was tested for coexisting interferents such as uric acid and ascorbic acid, and no discernible response was observed. After 90 days, the response of the biosensor remained almost unchanged, indicating very good stability.

Biosensing Techniques↗
PubMed2000

Multifractality of drop breakup in the air-blast nozzle atomization process.

The multifractal nature of drop breakup in the air-blast nozzle atomization process has been studied. We apply the multiplier method to extract the negative and the positive parts of the f(alpha) curve with the data of drop-size distribution measured using dual particle dynamic analyzer. A random multifractal model with the multiplier triangularly distributed is proposed to characterize the breakup of drops. The agreement of the left part of the multifractal spectra between the experimental result and the model is remarkable. The cause of the distinction of the right part of the f(alpha) curve is argued. The fact that negative dimensions arise in the current system means that the spatial distribution of the drops yielded by the high-speed jet fluctuates from sample to sample. In other words, the spatial concentration distribution of the disperse phase in the spray zone fluctuates momentarily, showing intrinsic randomness.

Journal Article↗
PubMed1998

Primary non-Hodgkin's lymphoma of the nasal cavity: prognostic significance of paranasal extension and the role of radiotherapy and chemotherapy.

BACKGROUND: This study was conducted to determine whether the paranasal extension of a primary non-Hodgkin's lymphoma (NHL) of the nasal cavity has any deleterious effect on patient outcome. METHODS: One hundred and seventy-five patients with previously untreated nasal NHL were reviewed. There were 2 with low grade, 107 with intermediate grade, 17 with high grade, and 49 with unclassifiable lymphomas. In 48 cases the immunophenotype was available and 46 were T-cell lymphoma. According to the Ann Arbor system, there were 133 patients with Stage IE, 28 with Stage IIE, 4 with Stage IIIE, and 10 with Stage IVE lymphomas. Stage IE was subdivided into limited Stage IE (i.e., confined to the nasal cavity [67 patients]) or extensive Stage IE (i.e., presenting with extension beyond the nasal cavity [66 patients]). For patients with limited Stage IE disease the treatment of choice was radiotherapy with or without chemotherapy. In patients with extensive Stage IE disease, treatment was comprised of a combination of chemotherapy and radiotherapy or radiotherapy alone. For patients with a more advanced stage of disease (IIE-IVE), chemotherapy was an integral part of the treatment and was completed by irradiation, especially for patients with Stage IIE disease. RESULTS: The actuarial overall survival (OS) and disease free survival (DFS) rates at 5 years for the whole group were 65% and 57%, respectively. The 5-year OS and DFS rates were influenced by stage, with a gradual decrease from 75% and 68% for Stage IE disease to 35% and 28% for Stage IIE disease, and 31% and 19% for Stage IIIE/IVE disease. Patients with limited Stage IE disease survived significantly longer (90% 5-year OS) compared with those with extensive Stage IE disease (57% 5-year OS; P < 0.001). For 67 patients with limited Stage IE disease, the 5-year OS was 89% with radiotherapy alone and 92% with radiotherapy and chemotherapy, whereas for 66 patients with extensive Stage IE disease, the 5-year OS was 54% with radiotherapy and 58% with combined modality therapy or chemotherapy (P > 0.05). CONCLUSIONS: The prognosis of patients with primary NHL of the nasal cavity is stage dependent. In this large cohort of Stage IE patients, it was demonstrated that the paranasal local extension was a significant prognostic factor associated with poorer treatment outcome. The authors believe that Ann Arbor Stage IE should be subclassified further into limited and extensive Stage IE. The addition of chemotherapy did not appear to modify significantly the survival of patients with either limited or extensive Stage IE disease. The extranodal progression observed in patients with extensive Stage IE and Stage IIE-IVE disease clearly illustrates the need for improvement of systemic treatment.

Adolescent↗
PubMed1998

Neuroendocrinology of melatonin in reproduction: recent developments.

The circadian melatonin rhythm with high levels in the dark period is important for the synchronization of reproductive response to appropriate environmental conditions in animals. The target sites of melatonin action on reproductive functions remain to be clarified. Using autoradiography (ARG) and radioreceptor binding assays with 2[125I]iodomelatonin, a melatonin agonist, as the radioligand, studies on the sites of melatonin action have increased significantly in the last ten years. The recent cloning of melatonin receptor subtypes also allowed the characterization of receptor(s) to the molecular level. Earlier reports have documented that the hypothalamic-pituitary axis plays a vital role in the regulation of reproduction by melatonin. This is supported in part by the demonstration of melatonin receptors in the suprachiasmatic nuclei (SCN) in the brain and pars tuberalis (PT) in the pituitary. However, the nature of SCN and PT involvement in the reproductive action of melatonin remains unknown. In addition to the hypothalamus and pituitary, the two classical sites of melatonin action, other targets have been identified. The recent demonstration of 2[125I]iodomelatonin binding sites or melatonin receptors in the testis, epididymis, vas deferens, prostate, ovary and mammary gland suggest the concept of multiple sites of melatonin action on the reproductive system. The presence of melatonin receptors in the said tissues is consistent with earlier reports of direct melatonin actions on different levels of the reproductive system. This multiple levels of melatonin action, from the hypothalamus, pituitary, gonads to other reproductive tissues form a robust system of photoperiodic control in animal reproduction. This would guarantee successful gestation and delivery of the offspring at a time with optimum food availability and ultimately favourable for the survival of species. Molecular and cellular studies of melatonin signaling system(s), its regulation and effects on downstream functional events in the future may provide new insights and directions for the study of the physiology and pharmacology of fertility and contraception in animals and humans.

Animals↗
PubMed1998

Asymmetrical testicular weights in mammals, birds, reptiles and amphibia.

The testes of different classes of animals (mammals, birds, reptiles and amphibia) were weighed. Some species showed inconsistent left-right asymmetric testicular weights, while other species (including amphibians, reptiles, some birds and some mammals) showed consistent asymmetry in their weights. In rodents, for example, five strains of mice consistently exhibited asymmetrical testes, with the right testis always being heavier than the left. In contrast, another strain of mice showed inconsistent bilateral asymmetry of the testes.

Amphibians↗
PubMed1998

Gossypol as a male antifertility agent--why studies should have been continued.

It has been nearly three decades since the beginning of nationwide research into gossypol as a male antifertility agent in China. Several lines of data implicating some side effects of gossypol were published which led to the termination of this area of research in China. The present review re-examines these data and points out the confusion surrounding issues such as hypokalaemia, irreversible azoospermia and other side effects. The prospects and related difficulties for gossypol as a potential male contraceptive are also discussed.

Animals↗
PubMed1998

[Changes of angiotensin II autocrine by cultured pulmonary artery smooth muscle cells exposed to anoxia].

Alterations of autocrine function of pulmonary arterial smooth muscle cells (PASMCs) might play an important role in development of hypoxic pulmonary hypertension (HPH). To test this hypothesis, the effects of hypoxia on angiotensin II (AT II) secretion by cultured new born bovine PASMCs were investigated. AT II secretion decreased significantly when PASMCs were incubated under 2.5% O2 hypoxic condition for 3 to 48 h (P < 0.01 vs control), but decreased further under anoxic condition (P < 0.01 vs control and 2.5% O2 group). Nitric oxide (NO) donor SIN-1 inhibited AT II secretion significantly under normoxic condition, but NO synthase inhibitor L-nitro-arginine (LNA) eliminated the inhibitory effect of anoxia on AT II autocrine and promoted AT II release. It was also found that the concentration of cGMP in PASMCs increased significantly (P < 0.01) at 24 h incubation in 0% O2, an effect that can be attenuated by LNA. Hypoxia stimulated 3H-TdR incorporation of PASMCs significantly (P < 0.001), while captopril exerts an inhibition in normoxic condition (P < 0.001), but without effect under hypoxic condition. The above results suggest that hypoxia can inhibit AT II secretion by inducing endogenous NO production in PASMCs. AT II autocrine is not involved in hypoxic proliferation of PASMCs, but a decrease of AT II may contribute to prevention of the development of HPH.

Angiotensin II↗
PubMed1998

[Modulations of proliferation between in vitro pulmonary artery endothelial cells and smooth muscle cells under hypoxia].

Vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) are structurally and functionally closely connected. Their interactions may play important roles in the development of hypoxic pulmonary artery hypertension. In the present study, mitogenic regulations between cultured new bovine pulmonary arterial endothelial cells (PAECs) and pulmonary arterial smooth muscle cells (PASMCs) under both normoxic and hypoxic conditions were investigated. Cell proliferation was assessed by 3H-thymidine incorporation and flow cytometry. Normoxic conditioned medium (CM) from cultured PASMCs inhibited 3H-thymidine incorporation of PAECs by 58% (P < 0.01), but normoxic or hypoxic CM from PAECs promoted or inhibited 3H-thymidine incorporation of PASM by 60% and 27% respectively (P < 0.01). When mixed PAECs and PASMCs were cultured for 24 h, relative 3H-thymidine incorporation of the mixed cells decreased by 22% (P < 0.01 vs monoculture) under normoxic condition, and increased by 75% or 44% under 0% O2 or 2.5% O2 (P < 0.01 vs normoxic mixculture). When PAECs and PASMCs were cocultured in either normoxic or hypoxic conditions, proliferation of PAECs was inhibited while that of PASMs was stimulated significantly (P < 0.01), as compared with that of homotypic cultured cells. These findings suggest that PAECs and PASMCs may mutually regulate their proliferation each other, and this mutual modulation may be changed under hypoxic condition.

Animals↗
PubMed1997

Seminoma arising in corrected and uncorrected inguinal cryptorchidism: treatment and prognosis in 66 patients.

PURPOSE: The purpose of this study was to analyze prognosis and treatment results for seminoma arising in corrected and uncorrected inguinal cryptorchidism (SCIC and SUIC). METHODS AND MATERIALS: We reviewed 66 patients with inguinal seminomas between June 1958 and December 1991 at the Cancer Hospital and Institute of Chinese Academy of Medical Sciences. Of these patients, 23 had prior orchiopexy and 43 presented with an inguinal form of cryptorchidism. At presentation, 17 of 66 (26%) patients had nodal metastases. This nodal involvement was 30% (7 of 23) for SCIC and 23% (10 of 43) for SUIC, respectively. These numbers are comparable with those in a series of patients treated for scrotal seminoma at our institution (26% vs. 20%). However, 3 of 23 (13%) patients who had prior orchiopexy presented with inguinal nodal metastasis as compared with 0 of 43 patients with SUIC or 4 of 237 patients with scrotal seminoma (p < .05). There were 49 stage I, 5 stage IIA, 8 stage IIB, 3 stage III, and 1 stage IV patients. All patients underwent radical orchiectomy and received further radiotherapy, chemotherapy, or both. Patients with stage I and stage II disease were treated primarily with radiotherapy, whereas patients with stage III and IV disease were treated with chemotherapy. RESULTS: The overall and disease-free survival at 5 and 10 years was 94% and 92%, 89% and 87%, respectively. The overall 5- and 10-year survival by stage was 100% and 100% for stage I, and 77% and 68% for stage II, respectively (p < .05). There was no significant difference in survival between SUIC and SCIC (93% vs. 96% at 5 years). Four patients developed relapse. Two of these four patients experienced relapse at the inguinal area, due to a marginal miss. Three of four patients with relapse were successfully salvaged, and one died of disease. CONCLUSION: Our results indicate that prognosis for inguinal seminoma is excellent and similar to that of scrotal seminoma. Postorchiectomy radiotherapy can be considered as the standard treatment for stage I and IIA inguinal seminoma. We recommend routinely including the para-aortic and ipsilateral pelvic nodes.

Adult↗
PubMed1997

Clinical characteristics, prognosis, and treatment of pelvic cryptorchid seminoma.

PURPOSE: To analyze the clinical characteristics, prognosis, and treatment outcome of pelvic cryptorchid seminoma (PCS), and to determine whether whole abdominal-pelvic irradiation for Stage I disease is necessary. METHODS AND MATERIALS: From 1958 to 1991, 60 patients with PCS were treated at the Cancer Hospital of Chinese Academy of Medical Sciences, Beijing. They presented with a lower abdominal mass and showed a predominance for the right side. A high proportion of patients with PCS [26 of 60 (43%)] had metastatic disease, compared to 20% of those with scrotal seminoma, and there was a tendency toward a higher frequency of pelvic nodal metastases. There were 34 Stage I, 6 Stage IIA, 11 Stage IIB, 5 Stage III, and 4 Stage IV patients. Of these 60 patients, 56 underwent laparotomy with or without cryptorchiectomy (37 radical orchiectomy, 7 partial orchiectomy, and 12 biopsy of the primary or cervical node), and 4 cervical node biopsy only. All patients were further treated with radiotherapy, chemotherapy, or a combination of both. Patients with Stage I and II disease received radiotherapy, whereas patients with Stage III and IV were treated with chemotherapy. RESULTS: The overall and disease-free survivals at 5 and 10 years were 92% and 87%, and 88% and 84%, respectively. The 5- and 10-year survivals were 100% for Stage I, 94% and 87% for Stage II, and 56% and 42% for Stage III/IV, respectively (p < 0.05). Volume of irradiation, i.e., whole abdominal-pelvic radiotherapy (10 patients), versus hockey-stick encompassing paraaortic, ipsilateral iliac nodes and the primary tumor or tumor bed (17) did not influence outcome in Stage I patients. Five patients relapsed within 2-12 years after treatment, and four of these patients were successfully salvaged. Four patients developed a second malignant tumor and died. CONCLUSION: Stage I and II PCS can be adequately controlled by radiotherapy regardless of the surgical procedure. Whole abdominal-pelvic irradiation for Stage I and IIA disease is not required, and fields can be limited to the paraaortic, ipsilateral iliac nodes and primary tumor or tumor bed. We recommend platinum-based chemotherapy for Stage IIB-IV PCS.

Adolescent↗
PubMed1997

[Effects of serotonin on the proliferation of pulmonary arterial smooth muscle cell under hypoxia].

The effects of hypoxia on the bovine pulmonary arterial smooth muscle cell (PASM) proliferation and serotonin transporter gene expression were investigated using 3H-Thymidine incorporation, immunocytochemical staining and mRNA dot blot hybridyzation, the results were as follows, PASM 3H-Thymidine incorporation increased in response to anoxia for 24 h (P < 0.05). The anoxia-induced increased in DNA synthesis of PASM was significantly stimulated by 5-HT (100, 10 and 1 mumol/L) (P < 0.001), but 5-HT did not increase 3H-TdR incorporation under normoxic condition. Immunocytochemical reaction of serotonin in PASM under normoxic condition was markedly stronger than that of anoxic PASM (P < 0.001). Dot blot analysis showed hypoxia increased serotonin transporter mRNA expression of PASM (P < 0.01). These results indicate that stimulation of PASM proliferation with enhanced serotonin transporter gene expression and high consumption of 5-HT in hypoxia or/and anoxia may take part in the development of hypoxic pulmonany hypertention.

Animals↗
PubMed1996

Autoradiographic distribution and physiological regulation of 2-[125I]iodomelatonin binding in rat epididymis.

Autoradiographic study was conducted to localize 2-[125I]iodomelatonin binding in the rat epididymis. In the peripubertal (6 weeks old), postpubertal (8 weeks old) and adult (3 months old) rats, intense specific 2-[125I]iodomelatonin labelling of the corpus epididymidis was observed. The intensity of 2-[125I]iodomelatonin binding in the distal epididymal segment was significantly decreased in orchidectomized rats but the effect could be reversed with testosterone replacement. The intensity of 2-[125I]iodomelatonin binding in the distal rat epididymal segment did not show any diurnal rhythmicity when mid-light period and mid-dark period levels were compared, and was unaffected by constant lighting. Our data suggest androgen-dependent expression of 2-[125I]iodomelatonin binding sites, independent of light-induced changes in circulating melatonin, in the rat corpus epididymidis. A novel role of melatonin and its receptor in the regulation of the functions of rat corpus epididymidis is strongly implicated.

Animals↗
PubMed1995

Genomic localization of tomato genes that control a hypersensitive reaction to Xanthomonas campestris pv. vesicatoria (Doidge) dye.

Xanthomonas campestris pv. vesicatoria causes bacterial spot, one of the most serious diseases of tomatoes. The lycopersicon esculentum accession 'Hawaii 7998' is the only reliable source of resistance to race 1 strains of the pathogen. This resistance is associated with a hypersensitive reaction controlled by multiple nondominant genes. The inoculated area becomes fully necrotic 24 hr after inoculation in 'Hawaii 7998,' whereas full necrosis is observed 5 and 4 days after inoculation in the susceptible species L. pennellii (LA 716) and their F1, respectively. An interspecific backcross population, using 'Hawaii 7998' as the recurrent parent, was analyzed to determine the linkage relationships between the resistance genes and 135 molecular marker loci. The range of responses of the BC1 population included those of the parents. Linkage to a hypersensitive response factor was assessed by comparing the rates of necrosis development between homozygous and heterozygous plants at 8 hr-intervals. Three factors that affect the hypersensitive response of 'Hawaii 7998' were detected. One factor is on the short arm of chromosome I, another on the long arm of chromosome I, and a third on the long arm of chromosome 5. These factors appeared to act independently and to have additive effects.

Chromosome Mapping↗
PubMed1994

Identification and characterization of 2[125I]-iodomelatonin binding sites in the rat epididymis.

Putative melatonin receptors in different parts of the male reproductive system of rats (Sprague-Dawley), mice (ICR), hamsters (Syrian) and guinea pigs (Dunkin-Hartley), rat epididymal sperm, and boar and human semen were studied by a radioreceptor assay using 2[125I]iodomelatonin as the radioligand. There was limited or no detectable binding of 2[125I]iodomelatonin to membrane preparations of rat testis, seminal vesicles, prostate, or sperm from rat, human, and boar. However, significant bindings of 2[125I]iodomelatonin to the epididymides of rat, mouse, hamster, and guinea-pig were demonstrated. The relative binding capacities of 2[125I]iodomelatonin to the distal epididymal segment in different rodent species was of the order rat mouse hamster guinea pig. The relative number of binding sites was much lower in the proximal segment than in the distal segment of epididymis. 2[125I]iodomelatonin binding to the distal segment of rat epididymis was studied in detail. The binding sites fulfilled all criteria for a receptor site; being stable, saturable, reversible, and of high affinity. The binding had an equilibrium dissociation constant (Kd) of 62.6 +/- 7.79 pmol/l (n = 7) and a density (Bmax) of 1.55 +/- 0.16 fmol/mg protein (n = 7). The Hill coefficient approached 1.0, suggesting a single class of 2[125I]iodomelatonin binding sites. Pharmacological studies revealed that these 2[125I]iodomelatonin binding sites were specific for melatonin receptors. In addition, there was an age-related change in the 2[125I]iodomelatonin binding sites in the rat distal epididymal segment. The binding increased from a lower value in 1-month-old rats to a higher adult value in the 1 1/2- to 24-month-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[A 5 year surveillance of blindness in Yilong Commune, Yian County, Heilongjiang Province].

A sample of 35,404 people in Yilong Commune, Yian County, Heilongjiang Province, has been under surveillance since 1985 when the primary eye care system was established. In 1985, there were 52 blind people, representing a blindness prevalence of 0.15%; in 1990, the figure was reduced to 44, representing a prevalence of 0.12%. During the 5 years in between, the original 52 blind people were reduced by 15, while, from 22 cases of blinding eye diseases, 14 new cases of blindness arose, of whom 7 cases were cured. The incidence of blindness was 0.09/1000. The new cases of blindness were mainly elderly people and children, and the blinding diseases were glaucoma, cataract and congenital/hereditary diseases.

Blindness↗
PubMed1992

The primary structure of fatty-acid-binding protein from nurse shark liver. Structural and evolutionary relationship to the mammalian fatty-acid-binding protein family.

The primary structure of a fatty-acid-binding protein (FABP) isolated from the liver of the nurse shark (Ginglymostoma cirratum) was determined by high-performance tandem mass spectrometry (employing multichannel array detection) and Edman degradation. Shark liver FABP consists of 132 amino acids with an acetylated N-terminal valine. The chemical molecular mass of the intact protein determined by electrospray ionization mass spectrometry (Mr = 15124 +/- 2.5) was in good agreement with that calculated from the amino acid sequence (Mr = 15121.3). The amino acid sequence of shark liver FABP displays significantly greater similarity to the FABP expressed in mammalian heart, peripheral nerve myelin and adipose tissue (61-53% sequence similarity) than to the FABP expressed in mammalian liver (22% similarity). Phylogenetic trees derived from the comparison of the shark liver FABP amino acid sequence with the members of the mammalian fatty-acid/retinoid-binding protein gene family indicate the initial divergence of an ancestral gene into two major subfamilies: one comprising the genes for mammalian liver FABP and gastrotropin, the other comprising the genes for mammalian cellular retinol-binding proteins I and II, cellular retinoic-acid-binding protein myelin P2 protein, adipocyte FABP, heart FABP and shark liver FABP, the latter having diverged from the ancestral gene that ultimately gave rise to the present day mammalian heart-FABP, adipocyte FABP and myelin P2 protein sequences. The sequence for intestinal FABP from the rat could be assigned to either subfamily, depending on the approach used for phylogenetic tree construction, but clearly diverged at a relatively early evolutionary time point. Indeed, sequences proximately ancestral or closely related to mammalian intestinal FABP, liver FABP, gastrotropin and the retinoid-binding group of proteins appear to have arisen prior to the divergence of shark liver FABP and should therefore also be present in elasmobranchs. The presence in shark liver of an FABP which differs substantially in primary structure from mammalian liver FABP, while being closely related to the FABP expressed in mammalian heart muscle, peripheral nerve myelin and adipocytes, opens a further dimension regarding the question of the existence of structure-dependent and tissue-specific specialization of FABP function in lipid metabolism.

Amino Acid Sequence↗
PubMed1992

Electrolytes, protein, and lactate dehydrogenase isozymes of parotid saliva in mineralocorticoid-treated rats.

Small quantities of parotid saliva were obtained from 7 of 11 rats in which hypokalemia was induced by treatment with deoxycorticosterone acetate (DOCA). Thirst in the treated rats was indicated by an increase in water consumption. A decrease of 28% in plasma potassium levels indicated that the DOCA-treated rats had become hypokalemic; chloride decreased 6-7% while sodium was unchanged. Saliva showed significant increases in potassium and protein and a decrease in sodium; lactate dehydrogenase-2 and -4 bands appeared darker on the electrophoretic profile. These changes are relevant to the clinical manifestations and diagnosis of hypokalemia.

Animals↗