Biomedical subjects
Publications and source records attributed to K Tang.
Various isomer matrices were used for laser-desorption ionization of mixtures of oligomers. It was found that the efficiency of production of oligomer ions changed drastically when different isomers were used as matrices. For selected matrix materials, parent oligomer ions with sizes up to 64 bases were observed.
Ferulic acid, 3-hydroxypicolinic acid (3-HPA), and 2,5-dihydroxybenzoic acid (2,5-DHB) were used as matrices in MALDI of various oligonucleotides. It was found that 2,5-DHB is an excellent matrix for polydeoxyribothymidylic acid. A poly-T oligonucleotide with a size of 130 bases was successfully detected. 3-HPA was found to be a good matrix for MALDI of homo-oligomeric deoxynucleotides as well as those containing four different bases. Parent ions of pd(A)60, d(T)100, d(G)40, and d(C)40 were observed, and a mixed-base oligonucleotide of 150-mer was also detected. Polymer ions of poly-A as large as 420-mer were measured; however, the efficiency for detecting poly-T with 3-HPA as a matrix was slightly worse than when 2,5-DHB was used. Comparisons of three matrices for various oligonucleotides is also presented.
Expression of the mouse metallothionein-I (MT) promoter/bovine growth hormone (bGH) or the phosphoenolpyruvate carboxykinase (Pepck) promoter/bGH fusion genes in male transgenic mice is associated with alternations in adenohypophyseal function and fertility. To determine the effects of these gene constructs on gonadotropin synthesis and secretion, we have examined basal and GnRH-stimulated LH and FSH release in vitro using static incubations and perifusions of the pituitary; we have also examined pituitary content of LH, FSH, LH beta mRNA, and FSH beta mRNA in MT/bGH and Pepck/bGH transgenic mice as well as in normal mice. In addition, we have measured LH and FSH release from normal pituitaries transplanted under the kidney capsules of Pepck/bGH transgenic or normal mice. We found that in Pepck/bGH transgenic mice, pituitary contents of FSH and FSH beta mRNA were reduced, while FSH release in vitro in pituitary incubations and perifusions was increased. Steady-state levels of LH beta mRNA as well as LH responses to GnRH in perifusions were reduced; LH release in incubations and pituitary LH content were not changed; and basal LH secretion in perifusions was increased. In MT/bGH transgenic mice, in which peripheral bGH levels are much lower than in Pepck/bGH mice, similar trends were observed, but most of the apparent differences between transgenic and normal animals were not statistically significant. When normal pituitaries were transplanted under the kidney capsules of Pepck/bGH transgenic mice, the expected decrease in LH and FSH secretion was attenuated and the response to GnRH stimulation was lost.(ABSTRACT TRUNCATED AT 250 WORDS)
The expression of the mouse metallothionein-I (MT) promoter/human GH (hGH) fusion gene leads to reduced fertility and increased plasma LH levels in male MT/hGH transgenic mice. To determine the effects of hGH on gonadotropin synthesis and release, we have examined basal and GnRH stimulated LH and FSH release in pituitary incubations and perifusions; and pituitary content of LH, FSH, LH-beta messenger RNA (mRNA), and FSH-beta mRNA in MT/hGH transgenic males and in their normal littermates. For comparison, similar studies were performed in GH and PRL deficient Ames dwarf mice in which plasma gonadotropin levels are known to be reduced. We have also measured the LH and FSH release from normal pituitaries transplanted under the kidney capsule of MT/hGH transgenic or normal mice. We found that in MT/hGH transgenic mice, there were parallel increases in unstimulated and GnRH stimulated LH release from pituitary incubation, in pituitary LH content and in LH-beta mRNA levels. In pituitary perifusion, the basal LH secretion was elevated, whereas LH responses to GnRH pulses were not altered. In transgenic males, FSH-beta mRNA was increased, whereas basal and GnRH-stimulated FSH release and pituitary FSH content did not differ from their normal controls. After normal pituitaries were transplanted to kidney capsules of MT/hGH transgenic mice, the expected decrease in LH and FSH secretion was attenuated and the responsiveness to GnRH stimulation was maintained. In Ames dwarf mice, all gonadotropin content and release, as well as pituitary beta-mRNA contents were decreased. We conclude that in MT/hGH transgenic mice, the expression of LH-beta and FSH-beta gene is increased. In addition, there is a translational or posttranslational inhibitory influence on FSH synthesis. Although our previous studies suggest that the effects of hGH gene expression on LH and FSH release are exerted primarily at the hypothalamic level, the present results suggest existence of GnRH unrelated peripheral factors which can directly stimulate pituitary gonadotropin synthesis and release. In Ames dwarf mice, the deficiency of GH and PRL, as well as TSH, is associated with decreased LH-beta and FSH-beta gene expression which may account for the reduction in plasma gonadotropin levels.
Mechanical deformation of normal ATP-replete human erythrocytes increased their permeability to Ca2+ sufficiently to turn on the Ca(2+)-activated K+ channel (the Gardos channel). When Ca2+ is absent, mechanical deformation of normal erythrocytes induces an equivalent increase the permeability of both Na+ and K+, In the presence of 0.1 to 1 mM Ca2+, a further increase in the K+ efflux rate was seen. There was no increase in Na+ flux above that induced by deformation itself. The involvement of the Ca(2+)-activated H channel was verified by showing the specific inhibitors of the channel, quinine and charybdotoxin, prevent the Ca(2+)-induced increase in K+ efflux. These results are consistent with a model of sickle cell dehydration proposed by Bookchin et al. ((1987) Prog. Clin. Biol. Res. 240, 193-200). The estimated rate of Ca2+ entry under these conditions (37 degrees C, 1000 dyne/cm2, and laminar shear) was about 1 mmol/loc per h.
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Fifty-seven cadaveric renal transplantations in fifty-five cases were analysed of them, thirty cases were prepared by continuous ambulatory peritoneal dialysis (CAPD group); twenty-seven transplantations in twenty-five cases were prepared by hemodialysis (HD group). Our data show that there is no significant difference in the survival duration between CAPD group and HD group; that there is also no significant difference in the survival duration between the two groups treated with the same immunosuppressive drugs, and that patients prepared by CAPD have a low risk of peritonitis after transplantation. It is better not to remove the Tenckhoff catheter until the graft function is stable so that it can be used for the transient peritoneal dialysis in the case of the insult of graft function or for the sampling of the peritoneal effusion for diagnosis of suspectable peritonitis after renal transplantation.
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Serum 18-hydroxycorticosterone, aldosterone, and potassium were measured under basal conditions in 34 patients with documented primary aldosteronism, 10 patients with essential hypertension, and 9 normal subjects. The results revealed that 22 of 23 patients with aldosterone-producing adenomas had 18-hydroxycorticosterone levels greater than 100 ng/dl, and all 9 patients with idiopathic adrenal hyperplasia had plasma levels less than 100 ng/dl. Two patients with unusual macromicronodular hyperplasia of the adrenal glands had levels greater than 100 ng/dl. We found a significant relationship between serum potassium and the ratio of 18-hydroxycorticosterone to aldosterone in patients with idiopathic adrenal hyperplasia, but not in those with an aldosterone-producing adenoma. We conclude that measurement of serum 18-hydroxycorticosterone is a useful predictor of the etiology of primary aldosteronism.
Tumor cell clones isolated from a rat 13762NF mammary adenocarcinoma and its spontaneous metastases were heterogeneous in their survival responses to continuous 42 degrees heating. Clones MTLn3 and MTF7 had similar initial survival responses; they were significantly less sensitive than clone MTC. Following the first decrease in survival, different magnitudes of induced thermal resistance were observed. When ratios of the first and resistant slopes of survival curves were compared (the thermotolerance ratio), the order of induced thermal resistance was MTLn3 greater than MTF7 greater than MTC. These clones were compared for the rates of synthesis of heat stress proteins (HSP). The same four major HSP at Mr 112,000, 90,000, 70,000, and 22,000 were induced or enhanced in all 3 clones. The rates of synthesis of these HSP were analyzed through a unique system of computer-assisted video densitometry and digitization. When all 4 HSP were analyzed as a group, the rates were significantly different (p less than 0.017), and the rank order of rates of synthesis was significant with MTLn3 greater than MTF7 greater than MTC. Induction kinetics of the individual HSP were different. Individually, the HSP at Mr 112,000, 90,000, and 22,000 were synthesized at significantly different rates between clones (p less than 0.001) but the Mr 70,000 HSP was not. Absolute total protein synthesis was highest for clone MTLn3, and MTF7 was higher than MTC but only marginally. Although absolute accumulations of these HSP could not be directly compared between these clones, the higher rates of HSP synthesis in these tumor cell clones correlated with more thermal resistance. These data support the working hypothesis that one or more of these HSP have a direct role in the mechanism(s) for inducing thermal resistance in rat tumor cells, but other factors such as total protein synthesis could modify the complex bio-chemical and phenotypic pathways involved in induced HSP and thermal resistance.
Maternal, fetal and umbilical blood glucose, insulin, and human growth hormone (HGH) levels were measured to determine their relation during labor and at delivery. There was a positive correlation between fetal glucose and HGH, as well as between the fetal insulin and HGH values. Higher birthweights were associated with lower umbilical venous HGH and higher insulin levels. Thus, the balance between insulin and growth hormone might be involved in the regulation of fetal growth.
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Cotton wilt defense reaction is a complicated continuous process and involves a battery of genes. In this study, we adopted suppression subtractive hybridization (SSH) technique to isolate differentially expressed ESTs from Gossypium barbadense variety 7124 during Verticillium wilt defense process. An array of 1165 clones from the subtractive library has been screened with reverse northern blotting, of which 131 ESTs were considered as over-expressed and 16 ESTs were down-regulated. Sequence analysis and blast search showed that 83 ESTs were homologous to 45 unique sequences in the databases. Among all these differentially expressed ESTs, at least three kinds of genes were characterized. The majority of ESTs with deduced identity to aerobic metabolism enzymes strongly expressed in the infection process. Likewise, ESTs similar to those reported for pathogen-related protein genes were also picked out in this study. These ESTs in combination with other kinase-like genes and a defensin-like EST constituted an assembly of genes responded during pathogens' infection. These results imply that sea-island cotton undergoes strong oxidative stress and results in a series of defense responses when attacked by V. dahliae. To our knowledge, this is the first report on the isolation of global ESTs during sea-island cotton defense reaction.
A novel Pto-like gene (designated as SsPto) is cloned from yellow-fruit nightshade (Solanum surattense). The full-length cDNA of SsPto is 1331 bp long with an open reading frame of 960 bp encoding a polypeptide of 320 amino acid residues. The deduced SsPto protein has a calculated molecular weight of 36.21 kDa with an isoelectric point of 6.18. Multiple sequence alignment shows that SsPto protein shares 71.4% and 71.6% identities to Pto proteins from Lycopersicon pimpinellifolium and L. hirsutum respectively. Genomic Southern blot analysis indicates the presence of a small family of SsPto in the S. surattense genome. SsPto is found to be constitutively expressed in the S. surattense plant with the highest expression in stems. However, under induction by TMV for 6 days, SsPto expresses the highest in roots. Further expression analysis reveals that the signaling components of defense/stress pathways, such as methyl jasmonate (MeJA), salicylic acid (SA), gibberellic acid (GA3) and hydrogen peroxide (H2O2), up-regulate the SsPto transcript levels over the control. Cold treatment, nevertheless, has no significant effect on SsPto expression whereas SsPto expression is down-regulated by dark treatment. Our findings suggest that this novel stress- and pathogen-inducible SsPto from S. surattense may participate not only in the defense/stress responsive pathways, but also in diverse processes of plant's growth and development.
A new WRKY gene was cloned from Brassica chinensis by rapid amplification of cDNA ends (RACE). The full-length cDNA of BcWRKY was 1175 bp long and contained a 924 bp open reading frame (ORF) encoding a putative W-box-binding protein of 308 amino acids. The predicted BcWRKY protein was found to have a potential bipartite nuclear localization sequence (NLS-BP) in its N-terminal region followed by a WRKY DNA-binding domain. Bioinformatic analysis revealed that BcWRKY resembled other WRKY domain-containing proteins from Arabidopsis (AtWRKY18), tobacco (WIZZ), parsley (PcWRKY4) and wild oat (ABF2). Expression of the BcWRKY gene could be induced by salicylic acid (SA), and influenced by Pseudomonas syringae pv. tomato strain DC3000 infection and wounding treatment. Our study implies that BcWRKY might have similar functions possessed by other WRKY genes such as inducing the expression of some defense-related genes and increasing plant's disease resistance ability.