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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 1,261 records · Page 70Linked to original sources
PubMed1993

Cloning and structural analysis of calmodulin gene from rice.

Full-length cDNA encoding rice (Oryza sativa, cv. Nongken 58S) calmodulin (CaM) mRNA has been cloned using polymerase chain reaction (PCR) with synthesized primers from the sequence of barley CaM gene. Sequence analysis revealed that the rice gene is 450 bp in length that and its predicted polypeptide consists of 148 amino acids. It differs from those that of barley and alfalfa in only one position, respectively. The nucleotide homology between rice and barley is 90%, between rice and alfalfa is 88%, between rice and rat is 73%.

Amino Acid Sequence↗
PubMed1993

Further study on the magnesium-mediated change in physical state of phospholipid modulates mitochondrial F0-F1-ATPase activity.

We have postulated that magnesium may play a role in altering the lipid fluidity of the bilayers, which would induce a change of conformation of the F0-ATPase portion (buried in the lipid core) of mitochondrial F0-F1-ATPase. Such change could be transmitted to the soluble F1 portion, resulting in higher enzymatic activity. The assumption was further supported by the results presented in the following: (1) A conformational difference for the F0-ATPase-containing proteoliposomes induced by the magnesium effect could be detected using a fluorescent probe acrylodan; (2) H(+)-translocation activity of F0-ATPase-incorporated proteoliposomes with magnesium, monitoring by fluorescence quenching of 9-aminoacridine or the bulk phase pH change, was higher than that without magnesium; (3) The magnesium effect on the reconstituted F0-F1-ATPase activity was greatly enhanced when the reconstitution was carried out in the presence of oligomycin sensitivity conferring protein (OSCP, a main component of the connecting link between the F1 and F0 sector of F0-F1-ATPase).

2-Naphthylamine↗
PubMed1993

Effect of acupuncture on weight loss evaluated by adrenal function.

In order to understand the relationship between patients' adrenal function and simple obesity and effect of acupuncture on it, the obesity indices, lipid indices, fasting blood-glucose, noradrenaline, dopamine, adrenalin and cortisol were observed. The results indicated that patients with simple obesity had hypofunction of the sympathetic-adrenal system and the hypothalamus-pituitary-adrenal system. Acupuncture treatment not only affected weight loss but also enhanced functioning of the two systems, suggesting that the effect of acupuncture on weight loss may be produced by enhancing the functions of both the sympathetic-adrenal system and the hypothalamus-pituitary-adrenal system.

Acupuncture Therapy↗
PubMed1993

[Pathologic, electron microscopic and experimental examination of band keratopathy].

One hundred and thirteen cases previously diagnosed as band keratopathy were reexamined by light microscopy and histochemistry, 10 cases of which were studied by TEM and 2 cases were studied by SEM. We find that the calcium deposition initially occur as fine calcific particles within the cytoplasm of epithelic cells and in the basal membrane and bowman's layer, which aggregated to form calcific spherules and large calcific masses extracellularly. When 3 normal corneal tissues were frozen and cultured, the calcium deposition occur in the superficial layer of bowman's membrane and in the stromal lamellae, Authors suggest that the degeneration and calcific abnormal metabolism of the cell caused by various factors is the main pathogenesis that leads to the calcific deposit. The evaporation and constructive destruction of the corneal surface in the interpiperbral area inhibits the formation of the lacrimal membrane and results in deposition of calcium salts in the superficial tissue of exposed cornea in a band configuration. The combination of glycosaminoglycan with calcium salts is the dynamics of aggregation of the fine calcific particles to form the calcific spherules and calcific masses.

Calcium↗
PubMed1993

[Prevention of reserpine induced experimental gastric ulcer in rat with amoxicillin a report of preliminary controlled study].

In recent years, amoxicillin (A) has been proved very effective in clearing helicobacter pylor (HP) and promoting ulcer healing. Is the cure due solely to the clearance of HP? Forty three Wistar rats were randomized into four groups to investigate the efficacy of A in preventing the experimental ulcer induced by reserpine and compare it with that of ranitidine (R) and antacid weishuping (W). A normal saline (NS) group was used as control. The total numbers of ulcer induced per rat for the NS, W, R and A groups were 7.8 +/- 5.1, 2.2 +/- 3.2, 1.0 +/- 1.2 and 2.1 +/- 1.9, respectively. The ulcer indices were 20.8 +/- 13.2, 4.5 +/- 7.7, 2.0 +/- 3.7 and 4.5 +/- 3.9, respectively. No HP was identified. The results indicated that A, R and W were all effective in preventing reserping induced ulcer with no significant difference (P > 0.05); they were significantly more effective than NS (P < 0.05). Since A is not an antacid and no HP existed in the experimental rats, there must be a mechanism of A involved in the prevention of experimental ulcer.

Amoxicillin↗
PubMed1993

[Renal structure and function in experimental diabetic rats following unilateral nephrectomy].

Renal structure and function in 50 streptozotocin-induced diabetic rats having unilateral nephrectomy and the effect of captopril treatment were observed for 3 months. The glomerular filtration rate, renal plasma flow, KW/BW, mean glomerular volume, wide glomerular basement membrane, glomerular mesangial cell proliferation as well as the ratio of 6-keto-PGF1 alpha/TXB2 of kidney tissue in the diabetic rats were significantly increased than those in the non-diabetic rats. These indexes were not significantly different between groups with and without captopril treatment. The results mentioned above illustrated that the obvious renal injury in diabetic rats receiving unilateral nephrectomy could be found as early as in the 3rd month of the experiment. These changes might be related to the metabolic abnormality of glucose and prostaglandins in the kidney and no effect of low dose captopril were noted on the renal injury.

Animals↗
PubMed1993

[Chart for estimating neonatal weight].

Estimation of neonatal weight can be used to aid management during gestation as well as to help choose the delivery method. In this study, the uterine height and abdominal circumference of 403 normal women were measured within a week before delivery. The babies were weighed immediately after birth and the data calculated by a computer and analyzed by stepwise regression analysis. A multiple linear regression equation was formed, as follows: Y gram (neonatal weight) = 101.24X1 (uterine height) +16.58X2 (abdominal circumference) -1907.64. This equation was used to construct a chart for estimating neonatal weight. Error analysis between the predicted and actual weights of 115 babies was conducted, and the results showed that the error was within +/- 300 g in 82.6%. The chart is considered a simple, convenient and accurate method for estimating fetal weight in the clinic.

Abdomen↗
PubMed1993

Morphometric analysis of benign and malignant adrenal pheochromocytomas.

At present, there are no reliable histologic features that can predict malignancy in adrenal pheochromocytomas other than the documentation of metastases. With the use of computerized interactive morphometry, our aim was to assess nuclei from tissue sections of confirmed cases of benign and malignant pheochromocytomas to determine whether consistent quantitative differences existed between the two. Eight benign cases with at least a 5-year follow-up and nine malignant cases with documented metastases were evaluated. Size distribution plots of the maximum nuclear cord length and of the nuclear area showed a narrow peak for the malignant cases, whereas benign cases showed a right-shifted curve with a wider peak. We concluded that nuclear morphometric analysis of benign and malignant pheochromocytomas yields two distinctive patterns and may be of utility in the assessment of future cases.

Adrenal Gland Neoplasms↗
PubMed1993

Lack of evidence for the involvement of cytochrome P-450 or other hemoproteins in metabolic activation of glyceryl trinitrate in rabbit aorta.

The present study was conducted to test the hypothesis that glyceryl trinitrate (GTN) metabolic activation in blood vessels is mediated by cytochrome P-450 or some other hemoprotein. The effects of cytochrome P-450 inhibitor [2-dimethylaminoethyl-2,2-diphenyl-n-pentanoate (SKF-525A) and metyrapone] on the response of rabbit aortic rings to GTN was determined by recording cumulative GTN dose-response curves in the presence of either or both inhibitors. The cytochrome P-450 inhibitors did not interfere with the ability of GTN to relax rabbit aortic rings. Treatment of rabbit aortic strips (RAS) with carbon monoxide (CO) was undertaken to elucidate a potential role of ferrous hemoproteins in mediating GTN-induced relaxation. CO did not significantly inhibit GTN-induced vasodilation of RAS. Biotransformation of GTN to glyceryl dinitrates by RAS exposed to CO for 5 min or nitric oxide (NO) for 10 min was determined by incubation of the tissues with 0.5 microM [3H]- or [14C]-GTN in the presence of CO or NO for 10 sec, 30 sec or 2 min. Neither CO nor NO exposure inhibited glyceryl-1,2- or -1,3-dinitrate formation by RAS after the 10-sec or 2-min incubation with RAS. For the 30-sec incubation, NO exposure did inhibit glyceryl dinitrate formation by RAS. This was deemed to be less important than the 10-sec data, the time just before the onset of relaxation. Therefore, emphasis is placed on lack of inhibition by NO at this earlier time point.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Morphometric analysis of neoplastic renal aspirates and benign renal tissue.

This study was designed to develop a practical morphometric procedure for the diagnosis of carcinoma in renal aspirates. We studied aspirates from renal cell carcinomas (grades 1-2) and normal kidneys. Video images of nuclei were traced on a high-resolution, touch-sensitive screen connected to an image analysis system. From each tracing the computer calculated nuclear perimeter length, nuclear profile area, maximal chord length, and the means and standard deviation for all measurements. Size distribution of nuclear profile areas and perimeter length in discrete bins ranged, respectively, from 30 to 80 at 10 microns2 intervals for areas and from 1 to 12 microns at 1-micron intervals for the maximum chords. The size distribution plots for the maximal chord of individual nuclei demonstrated an early narrow peak at low values for normal renal aspirates (peak located in the class ranging from 7 to 8 microns), while a broader, flatter peak with a shift to the right and a malignant tail was seen in renal cell carcinoma aspirates (peak located at 9-10 microns). These data were used for multivariate analysis to form two categories to establish a data base against which unknown cases could be tested. Multivariate analysis using a total of 14 variables yielded a value of 169.1 for the euclidean distances between the center of clusters of the neoplastic and normal renal aspirates and confirmed the classification with posterior probabilities of 1.0. From these data, automated classificatory analysis of 10 unknown cases was performed by means of the k-nearest neighbor procedure, with correct classification established in each case.

Biopsy, Needle↗
PubMed1992

Regioselectivity in the sulfation of some chemically-modified heparins, and observations on their cation-binding characteristics.

Two modified forms of heparin, polymers A and B, have been prepared, one containing residues of nonsulfated alpha-L-idopyranosyluronic acid (3) and the other residues of alpha-L-galactopyranosyluronic acid (7), in place of the normal alpha-L-idopyranosyluronic acid 2-sulfate (1). In addition, both A and B contained 2-acetamido-2-deoxy-alpha-D-glucopyranosyl 6-sulfate residues (6) in place of the corresponding N-sulfated residues (2) of the original heparin. These polymers were subjected to sulfation under various conditions. Examination of the products by NMR spectroscopy showed that polymer A was sulfated initially at position-3 of residue 3, and that slower substitution occurred at position-3 of 6. By contrast, polymer B exhibited low regioselectivity, as sulfation occurred with about equal facility at positions-2 and -3 of 7, and -3 of 6. The sulfation products had no significant anti Xa activity. Based on the paramagnetic effects of Cu2+ and chemical shift displacements induced by Ca2+, NMR spectroscopy was used to compare cation-binding properties of A and B with those of heparin. In contrast to heparin, which forms a complex with Cu2+ detectable at a level of < 10(-3) mol per dimeric unit of the polymer, neither A nor B exhibited an interaction with the cation. However, polymer A was found to bind Ca2+, in this respect being distinct from the related modification, 1-->6, which contains a 2-sulfate group in 1, as well as from polymer B.

Carbohydrate Sequence↗
PubMed1992

Biosynthetic regulation of proteoglycans by aldohexoses and ATP.

Biosynthetic regulation of renal glomerular heparan sulfate-proteoglycans by various aldohexoses (mannose, glucose, and galactose) was investigated. Isolated kidneys were perfused for 5 hr with medium containing [35S]sulfate, to label sulfated proteoglycans, or [35S]methionine, to label total glomerular proteins. All the hexoses, above 10 mM concentration, caused a significant decrease in the de novo synthesis of [35S]sulfate-labeled proteoglycans. The relative effectiveness of the hexoses was as follows: mannose much greater than glucose greater than galactose. The proteoglycans were of relatively lower molecular weights and exhibited reduced charge-density characteristics. Autoradiographic studies revealed a 2- to 3-fold decrease of grain density over the glomerular basement membrane and mesangial compartments, and immunoprecipitable heparan sulfate-proteoglycans were similarly decreased 2- to 3-fold. There was no significant decrease in the total [35S]methionine-labeled glomerular proteins or immunoprecipitable type IV collagen and laminin. Cellular ATP levels were dramatically reduced in all groups, and the maximal depletion was caused by mannose. Addition of ATP (0.1-1.0 mM) to the perfusion medium resulted in the normalization of the de novo synthesis and of the biochemical characteristics of heparan sulfate-proteoglycans. The relevance of decreased de novo synthesis of proteoglycans due to the depletion of ATP in hyperglycemic states is discussed in terms of increased glomerular permeability to plasma proteins, as seen in diabetes mellitus.

Adenosine Triphosphate↗
PubMed1992

cDNA cloning of a novel human ubiquitin carrier protein. An antigenic domain specifically recognized by endemic pemphigus foliaceus autoantibodies is encoded in a secondary reading frame of this human epidermal transcript.

Autoantibodies from a patient suffering from endemic pemphigus foliaceus (EPF), a blistering skin disease, were used to screen a lambda gt11 human keratinocyte cDNA library. One immunoreactive cDNA clone (lambda EPF5) containing a 900-base pair insert was isolated and subjected to further analysis. Eight of 25 EPF sera were shown to react with the EPF5 fusion protein on immunoblots. The EPF5 cDNA insert hybridized with a 1.2-kilobase epidermal RNA transcript on a Northern blot. Sequence analysis revealed that lambda EPF5 contained the complete coding sequence for a 24-kDa polypeptide exhibiting significant sequence homology with a family of enzymes known as ubiquitin carrier proteins, or E2s, which are an essential component of the ubiquitin-protein conjugation system. The homology was particularly high in the core region containing the active site cysteine. The keratinocyte ubiquitin carrier protein expressed in bacteria, and isolated either intact or as a glutathione S-transferase fusion protein, exhibited the ability to form a thiol ester linkage with ubiquitin in a ubiquitin activating enzyme (E1)-dependent manner, a characteristic property of ubiquitin carrier proteins. The E2 enzyme encoded by clone EPF5 is the first member of this protein family to be cloned from an epidermal source. Interestingly, the EPF autoantibody-reactive epitope and the ubiquitin carrier protein were shown to be encoded in two different translational reading frames. The relevance of the cloned EPF epitope in the pathogenesis of this autoimmune disorder remains to be determined.

Amino Acid Sequence↗
PubMed1992

T cell recognition of self-human histocompatibility leukocyte antigens (HLA)-DR peptides in context of syngeneic HLA-DR molecules.

It has been suggested that self major histocompatibility complex (MHC) peptides bound to self MHC molecules may be involved in the intrathymic induction of self tolerance. We studied the antigenicity of synthetic peptides derived from the first domain of DR beta 1*0101 chain in a DR beta 1*0101 responder. We found that a peptide corresponding to residues 21-42 of the beta chain could elicit the proliferation of autoreactive T cells. A T cell line (TCL-SUN) and 7 of 9 T cell clones (TCC) derived from TCL-SUN specifically recognized peptide 21-42 in the presence of APCs carrying the DR beta 1*0101 allele. DR beta 1*0101 positive APCs stimulated the TCCs in the absence of peptide, although the magnitude of the response was much lower than in cultures with peptide. This suggests that self DR1 molecules are continuously processed into peptides that are presented by the DR1 molecules on the surface of the cells. The data indicate that some T cells whose TCR binds to self MHC peptides presented by self MHC molecules are not deleted, although their ligand is continuously present. TCCs specific for peptide 21-42 presented in the context of DR1 were also stimulated by cells heterozygous for DR beta 1*0301 and 1601, indicating that some DR peptide-specific autoreactive T cells participate in alloreactivity.

Antibodies, Monoclonal↗
PubMed1992

Spontaneous transformation of rat ovarian surface epithelial cells: association with cytogenetic changes and implications of repeated ovulation in the etiology of ovarian cancer.

BACKGROUND: Ovarian surface epithelial cells undergo several rounds of division to repair the wound created by follicular rupture at the time of ovulation. This cyclical requirement for cell division, when not interrupted by the long anovulatory rest periods that occur during pregnancy and lactation, may contribute to the development of ovarian cancer. PURPOSE AND METHODS: To test this hypothesis, we isolated rat ovarian surface epithelial cells from 10 adult female Fisher rats, initiated two mixed-population and seven clonal cell lines, and repeatedly subcultured these cells in vitro for more than 20 passages. We then tested them for the acquisition of the following four features associated with transformation: 1) the loss of contact inhibition, 2) the capacity for substrate-independent growth, 3) the ability to form tumors when injected subcutaneously and/or intraperitoneally into athymic mice, and 4) cytogenetic abnormalities. RESULTS: Loss of contact inhibition was observed in all nine late-passage cell lines. Six of the nine late-passage, but none of the early-passage, cell lines tested exhibited a capacity for substrate-independent growth that was augmented in a dose-dependent manner by epidermal growth factor. Two late-passage cell lines (clone 2 and mixed-population 2) generated tumors in athymic BALB/c mice within 3 weeks following subcutaneous injection of 5 x 10(6) cells, whereas similar numbers of early-passage cells from the same cell lines failed to generate palpable tumors. Late-passage clone 7 cells were tumorigenic when 5 x 10(7) cells were injected intraperitoneally. Two of the cell lines analyzed exhibited alterations involving losses of part or all of one member of the chromosome 5 pair. Clone 2 possessed an interstitial deletion, del(5)(q21.3q24), consistent with the loss of an uncloned putative tumor suppressor gene at 5q22q23 previously reported to reside near the loci for the interferon alpha, interferon beta, and c-jun genes. Early-passage clone 7 cells exhibited chromosome 5 monosomy, while late-passage cells contained one normal chromosome 5 and a derivative (5q12q). Southern analysis of the three cell lines revealed no consistent loss of loci for the interferon and c-jun genes, although early-passage clone 7 cells had one half the gene copy number for the interferon beta and c-jun genes and both early- and late-passage clone 7 cells lacked DNA sequences hybridizing with the probe for interferon alpha. CONCLUSION: This pattern of passage-dependent spontaneous transformation of rat ovarian surface epithelial cells in vitro supports the hypothesis that repetitious ovulation contributes to the etiology of human ovarian cancer.

Animals↗