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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 919 records · Page 51Linked to original sources
PubMed1997

Gonadotropin alpha-subunit glycoprotein from channel catfish (Ictalurus punctatus) and its expression during hormone-induced ovulation.

Complementary DNA (cDNA) encoding the channel catfish (Ictalurus punctatus) gonadotropin (GTH) alpha-subunit glycoprotein was cloned by polymerase chain reaction (PCR) from a plasmid library made from pituitary RNA. Complete cDNA cloning was achieved by carrying out two PCR reactions: one with an upstream sense primer plus the universal sequencing primer, located downstream of the poly(A) sequence of the cDNA in the plasmid vector, to amplify the downstream portion of the cDNA; the other with a downstream antisense primer plus the reverse-sequencing primer, located upstream of the very 5' end of the cDNA sense strand in the plasmid vector, to amplify the upstream portion of the cDNA. The two amplified fragments overlapping about 70 bp. Nucleotide sequence analysis revealed that the catfish GTH alpha-subunit was 658 bp encoding 116 amino acids and harboring a 5' nontranslated region (NTR) of 42 bp and a 3' NTR of 265 bp. The deduced amino acid sequence of the catfish GTH alpha-subunit is highly conserved with those from other cloned teleost GTH alpha-subunits. The GTH alpha-subunit was highly expressed even before induction for ovulation in females during spawning season. Administration of carp pituitary extract (a spawning-inducing reagent) induced only 1.4-fold higher expression of the GTH alpha-subunit RNA, but included very rapid egg maturation and ovulation. This unexpected result indicated that the GTH alpha-subunit may not be the limiting factor for ovulation and spawning, which may be regulated by the change of proportional coupling of the GTH alpha-subunit with specific beta-subunit during hormone-induced ovulation.

Amino Acid Sequence↗
PubMed1997

Porcine aromatases: studies on tissue-specific, functionally distinct isozymes from a single gene?

Aromatase cytochrome P450 (P450arom) is expressed in a variety of tissues. Pigs express P450arom as bilaminar blastocysts in utero, and thereafter in the gonads, adrenal glands and placenta. Our studies also demonstrate the existence of porcine isozymes of P450arom which differ substantially in their amino acid composition and function. The placental isoform, most similar to P450arom in other mammals, consists of 503 amino acids. The ovarian isoform, expressed in both theca and granulosa cells, is a 501 amino acid protein exhibiting less than 20% of the activity of the placental isozyme. Furthermore, it is inhibited not only by CGS16949A but also by etomidate which does not inhibit the placental P450arom. Partial sequences generated by the rapid amplification of the cDNA ends (RACE) procedure indicate that the expression of a third isoform in the blastocyst is switched to the placental isozyme during differentiation of the fetal membranes. In addition, these transcripts, and others from the theca, granulosa, testes, adrenal glands and placenta demonstrate differences in the 5'-untranslated region (putative exon I) suggestive of tissue-specific alternative splicing. An identical 5'-untranslated sequence was obtained from transcripts expressed in the theca and granulosa. Testes and adrenal transcripts also have identical 5' ends, which differ substantially from the ovarian sequence. Blastocyst and placenta 5'-untranslated sequences differ from each other and from those expressed in the gonads and adrenals. Several tissue-specific transcripts thus encode porcine P450arom. Interestingly, distinct 5' sequences exist for ovarian and testes P450arom mRNAs, suggesting different promoters and therefore regulation in the male and female gonads. The molecular origins of the functional isoforms and the tissue-specific transcripts are uncertain, however partial genomic sequence and other genetic analyses suggest the existence of multiple genes. However, sequence alignment of the placental and ovarian isoforms indicates complete conservation of putative exon III, so that complex splicing remains a possibility. Clearly, the regulation of P450arom expression is more complex in the pig than in other vertebrates investigated to date.

Amino Acid Sequence↗
PubMed1997

The prognosis of biopsy-proven lupus nephritis in chinese patients: long term follow-up of 86 cases.

OBJECTIVE: To investigate the prognosis of lupus nephritis (LN) and its influencing factors in patients with lupus nephritis in China. METHODS: A retrospective study was carried out in 86 patients followed up for at least 5 years. Clinical features, serological and immunological tests were investigated. Renal biopsies were performed at the beginning of the study and repeated in some cases during the follow-up period. All the 86 patients had serum creatinine (Scr) level less than 132.6 mumol/L at the initial presentation and were divided into three groups according to the level of Scr at the end of the study. Group I: the patients with normal renal function (Scr < 132.6 mumol/L); Group II: the patients with mild-moderate renal insufficiency (132.6 mumol/L < or = SCR < or = 530.4 mumol/L); Group III: the patients with end stage renal failure (ESRF) (Scr > or = 530.4 mumol/L). RESULTS: Forty-seven patients reached clinical remission with normal renal function, 11 had with stabilization of renal function, although the systemic lupus erythematosis (SLE) activity relapsed repeatedly, while 28 subjects developed renal insufficiency after 60-170 (mean 88.12 +/- 28.23) months of observation. ESRF rate was 11.6% in this group of patients. Eight patients died (2 died of infections and 6 died of ESRF) during the follow-up period. At the beginning of the study the rates of hypertension, persistent anemia and hematuria in Group II were 50%, 70%, and 70% respectively, being much higher than those in Group I. The calculation of AI and CI in 60 patients revealed that there were 65% of patients with AI > or = 7 and 70% of patients with CI > or = 3 in Groups II and III, while in Group I there were only 32% of patients with AI > or = 7 and 19% of patients with CI > or = 3. Sixteen cases had pathologic class changed in 48 repeated biopsies. Seven cases changed to Class IV, 5 to Class II, 3 to Class V from other classes and one to class III from Class II. CONCLUSIONS: Factors associated with the development of renal insufficiency in these lupus patients included hypertension, anemia and hematuria. Renal biopsy evaluation offered additional prognostic information and showed that patients with severe active and chronic histologic changes were at risk for developing renal insufficiency. During the clinical course, the renal classification of LN changed in certain patients, thus the histologic classification of renal morphology at initial presentation did not fully predict the outcome. Renal involvement is very common in systemic lupus erythematosis (SLE) patients. Lupus nephritis (LN) is the most common form of secondary renal disease in China. It has various and unpredictable clinical features. The risks associated with its treatment have challenged investigators to detect the factors which may influence the survival rate of patients with LN and to develop the rational approaches to therapy. Decades of intensive investigation at many centers around the world had underscored the predictive value of demographic, clinical and laboratory data prior to treatment. Controversies still existed due to the difference in environment, race and the selection criteria of patients as well as the method used to evaluate the outcome. There are still some factors which are thought to have an impact on the prognosis of LN. Most of the articles on the prognosis of patients with LN were reported from Europe and America either about Caucasian or African-American patients. The prognosis of LN and its influence in Chinese patients need more elucidation.

Adult↗
PubMed1997

[Bacterial vaginosis in pregnant women].

OBJECTIVES: To determine the prevalence of bacterial vaginosis (BV) in pregnant women and to assess the association between BV and adverse pregnancy outcome. METHODS: Bacterial vaginosis was screened in 380 healthy pregnant women during different gestational weeks by clinical features and Grams stained vaginal smears. The pregnancy outcome of these gravidae was followed up. RESULTS: The prevalence of BV in pregnant women was 6.8% (26/380). The incidence of puerperal infection, neonatal infection, and jaundice of newborn were higher in women with BV than those without BV (14.3%, 9.5%, and 23.8% v.s. 2.2%, 1.3%, and 5.4%, respectively P < 0.05, P < 0.05, P < 0.005). CONCLUSION: Pregnant women with BV are associated with maternal infection, neonatal infection, and jaundice of newborn. It is necessary to treat BV during pregnancy.

Adult↗
PubMed1997

[The development of CTTM-1000 distant electrocardiogram central ambulatory monitoring system].

This article introduces a new electrocardiogam telephone transmitting and central ambulatory monitoring (receiving) system, and a device used for monitoring and transmitting the user's electrocardiogram. We also give some detailed discussion about the real time the flow display of ECG, and the signal preprocessing method based on the design of optimum FIR linear phase digital filter for the detection of QRS complexes.

Electrocardiography, Ambulatory↗
PubMed1997

[Determination of complements in serum and middle ear effusion of the patients with secretory otitis media].

Complements in serum and middle ear effusion were determined in 20 patients with secretory otitis media, and compared with those in the normal controls. The C5 and C1-INH in serum of the patients were significantly higher. On the contrary, C9 and B factor (Bf) were significantly lower, and the circulatory immunocomplex was also higher. In patients with secretory otitis media, the middle ear effusion levels of C3, C4 and C5 were significantly lower, and Bf and immunocomplex were significantly higher than those in serum. The results suggest that the ability of complements in clearing immunocomplex is low. Therefore, the immunocomplex may deposit in the mucosa of the middle ear. Thus the permeability of capillary will be increased, and the middle ear effusion occurs.

Adolescent↗
PubMed1997

[Blood pressure responses to cold pressor stress and its relation to sodium metabolism in salt-sensitive children].

OBJECTIVE: To investigate the blood pressure responses to cold pressor stress and its relation to sodium metabolism in salt-sensitive children. METHOD: 268 children aged 10.6 +/- 1.1 years were detected salt-sensitivity with the tests of oral saline load and furosemde sodium-volume depletion. Cold pressor stress test, sodium metabolism, and the related factors were measured. RESULTS: 25% of the children were detected to be salt-sensitive. The increased extent of blood pressure and its recovery time from peak to baseline in salt-sensitive children were significantly higher than those in non-salt-sensitive children during the cold pressor stress test (t = 5.14, 3.94, P < 0.01 and t = 2.16, P < 0.05). The increased extent of blood pressure and its recovery time during cold pressor test were correlated positively with red-cell sodium content, and were correlated negatively with 2 hour urinary sodium excreation during the oral saline load test. CONCLUSION: Children with salt-sensitivity have a remarkably increased blood pressure responses to cold pressor stress (sympathetic activity), which is related with abnormal sodium metabolism.

Blood Pressure↗
PubMed1997

[Early diagnosis of ectopic pregnancy by uterine curettage with serum hCG assay].

OBJECTIVE: To explore the value of uterine curettage combined with serum hCG assay in the diagnosis of early ectopic pregnancy (EP). METHODS: Judgement was done by uterine curettage pathologic examination of uterine content and determination of serum hCG in 61 patients with suspected EP with clinical symptoms, signs and auxillary examinations. RESULTS: Intrauterine pregnancy was confirmed in 17 patients by the presence of chorionic villi in the uterine contents. 26 patients were diagnosed as having EP by the absence of chorionic villi and elevated levels of hCG 24 hours after curettage. 18 patients who had no chorionic villi and the level of hCG fall down spontaneously after curettage were diagnosed having either intrauterine pregnancy or EP, mostly no further intervention. CONCLUSION: Diagnostic curettage with serum hCG determination can be used for differentiating intrauterine pregnancy from EP and it can also provide a reference for further arrangement.

Adult↗
PubMed1997

[Relationship between asthma and activated T-lymphocytes and interleukin-4].

Several studies have suggested that activated T-lymphocytes and its derived cytokines are involved in asthma pathogenesis. To investigate the role of activated T-lymphocytes and interleukin-4 (IL-4) in asthma pathogenesis, we measured soluble interleukin-2 receptor (sIL-2R) and IgE concentrations in serum and production of IL-4 in situumlated peripheral blood mononuclear cell cultures from asthmatics by means of ELISA. The results showed: (1) sIL-2R (512.82 x 10(3) +/- 264.62 x 10(3) U/L) and IL-4 (1,842.42 +/- 824.60 ng/L) levels in acute severe asthmatics were significantly higher than those of controls (242.32 x 10(3) +/- 108.64 x 10(3) U/L and 406.32 +/- 62.16 ng/L, P < 0.01); (2) there was a positive relationship between IL-4 and serum total IgE (r = 0.492); there was a significantly negative relationship between IL-4 and FEV1% (r = -0.821, P < 0.05); (3) after intravenous administration of dexamethasone (DXM) 5 mg daily for 5 days, sIL-2R and IL-4 decreased respectively to (332.61 x 10(3) +/- 124.62 x 10(3) U/L and 314.10 +/- 72.08 ng/L, P < 0.05). These data indicate that activated T-lymphocytes and its derived IL-4 play an important role in asthma pathogenesis and that the effect of steroid on the treatment of asthma is partly due to inhibition of activated T-lymphocytes and IL-4 release.

Adolescent↗
PubMed1997

[Effects of mixture of 22 kinds of volatile organic compounds on human body at different temperature].

Ten healthy volunteers were exposed to mixture of 22 kinds of volatile organic compounds with concentrations of zero to 10 mg/m3 at the temperature of 18, 22 and 26 C, respectively in an artificial climate room for 60 minutes a day and six days week for two consecutive weeks to study their effects on human bodies. Results showed that quality of indoor air decreased significantly, odor intensity increased, number of the subjects who need more ventilation increased, and irritation to eyes, nose and skin intensified under the mixture concentration of 10 mg/m3 and at temperature of 26 degrees C. No significant changes in psychological tests, tear film stability and cytological studies were found. Room temperature at 26 degrees C has a significant synergetic effects on human health. Therefore, quality of indoor air can not be evaluated only by organic compounds polluted in air, but by meteorological conditions.

Adolescent↗
PubMed1997

[The identification and isolation for Pseudomonas vesicularis].

A Gram-negative rod bacteria isolated from the hydrocardia of a hydropericarditis patient was reported. Maincharteristics of the strain are respiratory metabolism, oxidse positive and motility by one polar flagella. Through systematic morphological, physiological and biochemical identification; calculation of G+C mol%, and examination with Biolog Automated Systems, the species of Pseudomonas vesicularis are identified. We pointed out that the strain can infect an immuno-suppressed individual. The change of taxonomic position of the species was discussed.

Female↗
PubMed1997

[Identification and expression of ribulose 1,5-bisphosphate carboxylase/oxygenase gene from Thiobacillus versutus].

The chromosomal DNA of Thiobacillus versutus was hybridized with various heterologous ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) gene as probes. Only Rhodobacter sphaeroides form I RubisCO gene showed homology with T. versutus. The RubisCO gene fragment of T. versutus was isolated using the RubisCO gene of R. sphaeroides as a probe. And the RubisCO gene of T. versutus can express in E. coli cell.

DNA, Bacterial↗
PubMed1997

[Homology analysis of RubisCO gene of Thiobacillus versutus with extremelly acidophilic thiobacilli].

The chromosomal DNA of Thiobacillus thiooxidans and T. versutus was digested with restriction enzymes, blotted to nylon membrane by the way of Southern, and hybridized with the gene probe of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) from T. ferrooxidans. The result showed that T. thiooxidans exhibited high homology with the probe anc T. versutus was less homology with it. However T. versutus can hybridize with the gene probe of RubisCO from Rhodobacter sphaeroides, which indicated that they had high homology with each other. As RubisCO was highly reserved in the evolutionary, they should be divided into different group.

DNA, Bacterial↗
PubMed1997

[Conditions for the overexpressions of copper--resistant proteins from Escherichia coli].

There were five copper--resistant proteins encoded in the copper resistant plasmid pRJ1004 from Escherichia coli. The conditions for the overexpressions of two of the five, PcoC and PcoE, were reported in this paper. For the overexpression of PcoC using IPTG (Isopropyl-beta-D-thiogalactoside) as inducer, the best conditions were: medium, LB; IPTG concentration, 0.1 mmol/L; inducing time, one and half hours. For the overexpression of PcoE using CuSO4 as inducer, the best conditions were: medium, LB; CuSO4 concentration, 2.0 mmol/L; inducing time, one and halfhours.

Bacterial Proteins↗
PubMed1997

[Changes of early renal function before and after using mannitol in patients with cerebral apoplexy].

The alteration of renal function after initiation of mannitol infusion were monitored in 20 patients with cerebrovascular accident to evaluate whether mannitol has nephrotoxicity effects. Serum creatinine and urea nitrogen were increased after initiation of mannitol infusion, but hadn't reached stagistical significance. Urinary and serum alpha 1-microglobulin, beta 2-microglobulin and urinary NAG, gamma-GT were significantly increased after 5-10 days successive infusion of mannitol (P < 0.05). The results suggest that the acute nephrotoxicity effect of mannitol should not be ignored.

Adult↗
PubMed1996

Age-dependent effects of glutamate toxicity in the hippocampus.

While prolonged seizures can cause brain damage at any age, the extent of brain damage following prolonged seizures is highly age-dependent. Seizures in the immature brain are followed by far less histological damage than seizures of similar duration and intensity in mature animals. The reasons for this age-related phenomenon are unclear. Seizure-induced cell death may be due to the neurotoxic effects of excessive glutamate release, we tested the hypothesis that the immature brain is less vulnerable to glutamate-induced neurotoxicity than the mature brain. We administered equal amounts of glutamate (0.5 mumol in 1.0 microliter) unilaterally into the CA1 subfield of the hippocampus of rats at postnatal (P) days 10, 20, 30, and 60. Equal volumes of saline were injected in the contralateral hippocampus. Rats were killed 7 days later and their brains were examined for hippocampal cell loss. The size of the resultant hippocampal lesion was highly age-dependent. Minimal cell loss was noted in the P10 rats, lesions in the P20 rats were smaller than those at P30 and P60, which were similar in extent. This study demonstrates that the extent of glutamate neurotoxicity in the hippocampus is highly age-dependent, with immature hippocampi relatively resistant to glutamate-induced cell death.

Aging↗
PubMed1996

The existence of a hexameric intermediate with molten-globule-like properties in the thermal denaturation of bovine-liver glutamate dehydrogenase.

We have studied the thermal denaturation of hexameric beef-liver glutamate dehydrogenase by itself and in the presence of ADP and guanidine-HCl by a variety of techniques. In differential scanning calorimetry studies, the observed melting temperature and total enthalpy of denaturation show no dependence on protein concentration, but do show significant dependence on the scan rate. This suggests that the overall denaturation process is irreversible and kinetically controlled. Isothermal unfolding kinetics from spectrophotometry confirm this result. The size of the protein, as shown by quasi-elastic light scattering measurements, does not change during the denaturation process. We interpret these results in terms of the following model: N6 reversible N'6-->6U(-->F) where N6 and N'6 are, respectively, the native hexamer and a hexameric, highly folded high-enthalpy species, U is the unfolded monomer and F is some final aggregated state. The kinetic intermediate, N'6, possesses the properties of one definition of a molten globule, having a very high enthalpy and a hexameric compact structured form. This "molten globule" is an obligatory intermediate in the unfolding pathway of the protein. The stabilization of the protein by ADP is due to the modulation of the high-enthalpy two-state predenaturational E reversible E' transition, resulting in the lowering of the energy of the native state of the protein.

Adenosine Diphosphate↗