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Biomedical subjects

Z Xu

Publications and source records attributed to Z Xu.

At least 577 records · Page 32Linked to original sources
PubMed1992

[Two pairs of particular structures of mandibular joints of mammalian sorex].

The mandibular joints of Chinese Anouroserex squamipes, spuamipes, MILNE-EDWARDS were examined by gross and microscopic studies. We discovered that there were two pairs of joints in these animals. The upper pair of joints, named lateral mandibular joints, were placed on both sides under the parietal bone. The lower pair of joints, named skull-base mandibular joints, were placed on both sides of the skull-base. These two pairs of joints could not be observed simultaneously in the same plane either sagittally or frontally. The lateral fossa and condyle were obliquely from outward, backward and upward to inward, forward and downward on both sides; the fossa looked like a groove concave downward, and the head of the condyles appeared in a cylindrical form. The lower fossae and condyles were transversely forward and inward from the lateral mandibular joints; the fossa looked like a shallow spoon concave upward, and the condyle appeared in a flat surface to fit the upward fossa. The sorex likes to dig holes on the ground to live in and search for insects in the soil to eat. The skull-base mandibular joints will support the jaw to counteract the digging force and protect the lateral mandibular joints from injury. This study has suggested that the morphology of the mandibular joints is adapted to their functional requirements during evolution.

Animals↗
PubMed1992

[Distribution of type IV collagen, laminin and fibronectin during naris formation in the chick embryo].

The presence and distribution of extracellular matrix (ECM) macromolecules were analyzed in the facial primordia of chick embryos from stages (22-28) of development corresponding to naris formation. Frozen sections through the nasal placode, medial nasal processes and lateral nasal processes were prepared for indirect immunofluorescence employing a biotin-avidin DCS system using monoclonal antibodies against type IV collagen, laminin and fibronectin. The results demonstrated that ECM played a very important role in regulating migration, adhesion and anchorage of cells during morphogenesis. Strong fluorescence of basal lamina was present in the areas of rapid ingrowth of the nasal placode. It was suggested that ECM has very important guiding and regulating role during naris formation in chick embryo.

Animals↗
PubMed1992

[Farm irrigation index for culturing Panax ginseng C.A. Meyer].

The growth and yield of annual and perennial Panax ginseng were observed by applying methods of mini-irrigation and irrigation under different negative pressures of soil humidometer. After four experiments optimum values of negative pressure were found to assist timely irrigation, thus providing scientific criteria of rational irrigation and automated mini-irrigation for culturing Panax ginseng.

Humidity↗
PubMed1992

[Hyponatremia in patients with ascites complicating liver cirrhosis].

Eighty unselected cases of hyponatremia complicating liver cirrhosis were analysed. Of these cases, 20 had sodium levels less than 135 mmol/L, 48 less than or equal to 130 mmol/L and 12 less than or equal to 125 mmol/L. 5 cases developed acute hyponatremic syndrome after abdominal paracentesis and high-dose of diuretics. Of these 5 cases, 1 died and 4 recovered after immediate infusion of 3% sodium chloride (200-300 ml/d intravenously for 7-10 days). Both the crystal and colloid pressure of blood determined in 10 cases were less than normal. The sodium level of the ascitic fluid determined in 5 cases was higher than that of serum. Respiratory alkalosis complicated with metabolic alkalosis or acidosis were the main features of acid-base disorders. These might be due to alkalinizing agents therapy, infection and hepato-renal syndrome. Based on these clinical studies, it was shown that paracentesis and diuretics are the main causes of acute hyponatremic syndrome, so these measures should be taken carefully in patients with hyponatremic state previously, especially in patients with poor general, hepatic and renal conditions.

Acid-Base Imbalance↗
PubMed1991

Effect of intracerebral injection of monoclonal acetylcholinesterase antibodies on cholinergic nerve terminals in the rat central nervous system.

In the rat, unilateral intrastriatal injection of monoclonal antibodies to acetylcholinesterase (AChE) produced ipsilateral disappearance of AChE-positive nerve terminals within striatum and adjacent cortex. No alterations in striatal staining patterns were observed for tyrosine hydroxylase, somatostatin, neuropeptide Y, substance P, or neurotensin. Ultrastructural studies demonstrated the presence of degenerating AChE-positive boutons ipsilaterally, while tyrosine hydroxylase positive terminals seemed unaffected. Apomorphine administration to rats which had received unilateral antibody injection resulted in ipsilateral rotational behavior. These data suggest that selective effects on cholinergic terminals with functional deficits can be produced within the central nervous system by intracerebral injection of AChE antibodies.

Acetylcholinesterase↗
PubMed1991

Essential fatty acids and serine as plasmalogen precursors in relation to competing metabolic pathways.

Interest in altered ether-lipid metabolism, associated with peroxisomal disorders including adrenoleukodystrophy and Zellweger's syndrome, has highlighted present limitations in our understanding of the biosynthesis and turnover of plasmalogens. These 1-alkenyl ethanolamine phosphoglycerides are major phospholipids in brain, vascular tissue, neutrophils, and most tumors, and they constitute 15-20% of total phospholipids in cultured glioma cell. In glioma, turnover of polyunsaturated acyl chains in the sn-2 position of plasmalogens was examined in relation to selectivity for the (n - 3) and (n - 6) families. Remodeling of acyl chains was more dependent on chain length than on selectivity between families, consistent with plasmalogens enriched in polyunsaturated, but not specifically (n - 3), fatty acids. Extracellular serine was a precursor of serine and ethanolamine phosphoglycerides and was associated with plasmalogens due to decarboxylation and headgroup exchange. Incorporation of extracellular serine ceased within 8 h, even though more than 50% of the label remain in the medium. Analyses of medium and cellular water-soluble components indicated rapid conversion of serine to glycine and other metabolites not used in phospholipid biosynthesis. Thus, nutrient molecules as precursors of plasmalogens are involved in complex competitive interactions. As functions of plasmalogens are clarified, regulation of plasmalogen turnover becomes an increasingly important issue and elucidation of these processes is essential.

Adrenoleukodystrophy↗
PubMed1991

[Pharmacological studies on Bombyx mori L].

The toxicity of the Bombyx mori extract is very low. It can promote the growth of under-aged male mice, and increase markedly the weight of the prostate glands, seminal vesicles and preputial glands in castrated rats of mice. The results of the experiments have shown that Bombyx mori has androgen-like action.

Animals↗
PubMed1991

Induction of antitumor activity and experimental expansion of human lung cancer-infiltrating lymphocytes.

In order to look for effector cells which are more efficient and less toxic than LAK cells induced from PBL for use in adoptive immunotherapy, we studied the antitumor activity and in vitro expansion of tumor infiltrating lymphocytes (TIL) from human lung cancers and compared their cytological properties with those of autologous PBL. The results showed: 1) Large numbers of TIL could be obtained from lung cancer tissue, approximately 1-5 x 10(8)/g tumor tissue, with an average TIL to tumor cell ratio of 2.3:1 (21 samples). 2) Fresh TIL were not cytotoxic against either NK-sensitive or -resistant tumor targets. After culturing for 6 to 8 d in the presence of rIL-2, TIL showed significant cytotoxicity and were able to kill autologous and allogeneic tumor targets and fresh solid tumor targets. 3) When maintained in the presence of rIL-2, TIL were able to continue proliferating and expanding for more than 2 mon, with expansion indices of 4-512. TIL stopped proliferating following the disappearance of autologous tumor cells in the culture. 4) Chronological studies revealed that the cytotoxicity appeared after 4 days in culture and reached a peak on the 14th day, and cultured TIL remained cytotoxic for at least 4 wk.

Adenocarcinoma↗
PubMed1991

[One-stage reconstruction following resection of oropharyngeal carcinoma].

Fifty-nine cases undergone one-stage reconstruction following radical resection for oropharyngeal carcinoma were reviewed. Pectoralis major myocutaneous flap has been our first choice for reconstruction of surgical defects. A composite repair with forehead island flap and mucosal flap of the posterior pharyngeal wall for defect of the total soft palate was recommended. Preoperative radiation had some influence on wound healing. The 3 and 5 year survival rates were 58.1% and 41.7% respectively, and the cosmetic and functional restorations were satisfactory in most patients operated.

Adult↗
PubMed1991

[Gas chromatograms of fatty acids from Rickettsia and their similarities].

Fatty acid compositions of 7 strains of Rickettsia were analyzed by a on-line GC/MS system. These strains were R. prowazekii E, R. conorii Simko, R. rickettsii R, R. sibirica Barbash and 246, R. sinkiangensis Jinghe, and R. heilungkiangensis 54. The samples were purified by means of the concentrated salt-ether method. There were about 50 peaks in the fatty acid profiles, and 16 of these peaks were determined, i.e. C22:0, C19:0, C18:0, C18:1, C18:2, C17:0, C16:0, C16:1, 3-OH-C14:0, C15:0, C14:0, C13:0, 2-OH-C12:0, C12:0, 2-OH-C10:0, and C11:0. The major fatty acids were the saturated straight chain acids (e.g. C16:0, C18:0, C14:0) and the unsaturated straight chain acids (e.g. C18:1, C18:2, C16:1). Similarities of fatty acid profiles of tested strains were discriminated by the improved Kulik-Vincent method. The result showed that the KV's coefficient of strains Jinghe and 246 was 97.0%, and the KV's coefficient of strains 54 and the others was 81.6-94.6%.

Fatty Acids↗
PubMed1991

[Electrophysiological effects of berbamine on ischemic ventricular tachyarrhythmia].

The effects of berbamine (Ber, 10 mg.kg-1 iv) on ischemic ventricular tachyarrhythmia and electrophysiologic consequences in both normal and ischemic myocardia were studied in the open-chest dogs subjected to programmed electrical stimulation (PES) on 5-8 d after acute myocardial infarction. Its effects were compared with procainamide's (PA). Both drugs distinctly lengthened the QTc interval and the effective refractory period (ERP) of normal and infarct ventricular myocardium, decreased the dispersion of ERP in infarct myocardium (IDR) and the dispersion of ERP in left ventricle (VDR), and increased the diastolic excitability threshold (DET) of normal and infarct ventricular myocardium remarkably. The PES-induced ventricular tachycardia (VT) or ventricular fibrillation (VF) was prevented in 5 out of 6 dogs treated with berbamine and procainamide respectively. (Normal saline did not prevent PES-induced VT or VF). The results suggest that berbamine may be effective in preventing the onset of reentrant ventricular tachyarrhythmia after myocardial ischemic damage.

Alkaloids↗
PubMed1990

Purification and characterization of sea urchin initiation factor 2. The requirement of guanine nucleotide exchange factor for the release of eukaryotic polypeptide chain initiation factor 2-bound GDP.

Protein synthesis in sea urchin eggs is stimulated dramatically upon fertilization. We previously demonstrated that this stimulation is primarily due to an increase in the rate of polypeptide chain initiation which in turn may be regulated at the level of recycling of eukaryotic initiation factor 2 (eIF-2) (Colin, A. M., Brown, B. D., Dholakia, J. N., Woodley, C. L., Wahba, A. J., and Hille, M. B. (1987) Dev. Biol. 123, 354-363). We have now purified eIF-2 from sea urchin Strongylocentrotus purpuratus blastulae to apparent homogeneity by chromatography on DEAE-cellulose, phosphocellulose, Mono Q, Mono P, and Mono S columns. The factor, which differs from mammalian eIF-2, is composed of three non-identical subunits with apparent molecular weights of 40,000-alpha; 47,000-beta, and 58,000-gamma as estimated by sodium dodecyl-polyacrylamide gel electrophoresis. Antibodies raised against rabbit reticulocyte eIF-2 do not cross-react with sea urchin eIF-2. The binding of Met-tRNA(f) to sea urchin eIF-2 is totally dependent on GTP. A 4-fold stimulation in the rate of protein synthesis in unfertilized sea urchin egg extracts is observed by the addition of 1 micrograms of purified eIF-2. The factor also binds GDP to form a binary (eIF-2.GDP) complex which is stable in the presence of Mg2+. GDP binding to sea urchin eIF-2 inhibits ternary (eIF-2-GTP.[35S]Met-tRNA(f) complex formation. The rabbit reticulocyte guanine nucleotide exchange factor (GEF) catalyzes the exchange of GDP bound to sea urchin eIF-2 for GTP and stimulates ternary complex formation. The requirement of GEF for the recycling of eIF-2 suggests that protein synthesis in sea urchins is similar to that in mammalian systems and may also be regulated at the level of GEF activity. The reticulocyte heme-controlled repressor phosphorylates the alpha-subunit of eIF-2 from both sea urchins and rabbit reticulocytes. However, casein kinase II which phosphorylates the beta-subunit of the reticulocyte factor specifically phosphorylates the alpha-subunit of sea urchin eIF-2. In this respect, the sea urchin factor is similar to eIF-2 isolated from other nonmammalian sources. Since both heme controlled repressor and casein kinase II phosphorylate the alpha-subunit of sea urchin eIF-2 caution should be exercised when interpreting the significance of eIF-2(alpha) phosphorylation in sea urchins.

Animals↗
PubMed1990

Cell-free translation systems prepared from starfish oocytes faithfully reflect in vivo activity; mRNA and initiation factors stimulate supernatants from immature oocytes.

Meiotic maturation stimulates a change in the translation of stored mRNAs: mRNAs encoding proteins needed for growth of oocytes are translated before meiotic maturation, whereas those encoding proteins required for cleavage are translated after meiotic maturation. Studies of translational regulation during meiotic maturation have been limited by the lack of translationally active cell-free supernatants. Starfish oocytes are ideal for preparing cell-free translation systems because experimental application of the hormone 1-methyladenine induces their maturation, synchronizing meiosis. We have prepared such systems from both immature and mature oocytes of starfish. Changes in protein synthesis rates and the specificity of proteins synthesized in these cell-free translation supernatants mimic those seen in vivo. Supernatants both from immature and mature oocytes have a high capacity to initiate new translation because 90% of the proteins made are newly initiated from mRNAs. Cell-free supernatants from mature oocytes have a much higher rate of initiation of translation than those from immature oocytes and use the 43S preinitiation complexes more efficiently in initiation of translation. Similarly, we have shown that mRNAs and initiation factors are rate limiting in cell-free translation systems prepared from immature oocytes. In addition, cell-free translation systems prepared from immature oocytes are only slightly, if at all, inhibitory to cell-free translation systems from mature oocytes. Thus, soluble inhibitors, if they exist, are rapidly converted by cell-free supernatants from mature oocytes. The similarities between translation in our starfish cell-free translation systems and in intact oocytes suggests that the cell-free translation systems will be useful tools for further studies of maturation events and translational control during meiosis.

Animals↗