小鼠体内脾脏,骨髓及精原细胞姐妹染色单体交换的比较研究

本文对几种化学诱变剂诱发小鼠体内脾脏、骨髓和精原细胞的SCE进行了比较研究,同时分析了几类常见化合物在小鼠脾脏细胞中诱发SCE的活力。结果显示诱变剂在脾脏细胞中诱发SCE比骨髓和精原细胞敏感。几类化合物都能显著地诱发小鼠脾脏SCE的增加,与对照相比差异显著(P<0.05)或极显著(P<0.01),说明利用小鼠脾脏细胞检测环境诱变物是相当灵敏的。     

Processing and transfer of epidermal growth factor in developing rat jejunum and ileum

Using everted sac technique we demonstrated the transfer of ¹²⁵I-mEGF across the jejunal and ileal walls of suckling, weanling and adult rats. The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline. RP-HPLC analysis detected carboxy-terminal processing of ¹²⁵I-mEGF in suckling and adult rat jejunum and ileum. Suckling rat jejunum produced ¹²⁵I-des(53)mEGF and ¹²⁵I-des(49–53)mEGF, whereas ¹²⁵I-des(48–53)mEGF was detected in suckling rat ileum or adult rat jejunum and ileum. All three forms of ¹²⁵I-mEGF bound to anti-EGF antibody and EGF receptors. The receptor binding of ¹²⁵I-des(53)mEGF was higher than that of ¹²⁵I-mEGF, but those of ¹²⁵-des(49–53)mEGF and ¹²⁵I-des(48–53)mEGF were greatly diminished. Results indicate a carboxy-terminal processing of mouse EGF during uptake and transfer in the small intestine of developing and adult rats, and the resulting products showed altered receptor binding. An identical amino acid sequence of the C-terminal pentapeptide of EGF from mouse, human and possibly rat may suggest a biological significance of C-terminal processing of EGF in the small intestine.     

己酸菌LⅡ己酸发酵过程中生理及代谢特点

在了解了产己酸细菌ＬＩＩ的发酵最适条件的基础上,进一步对己酸发酵过程中的生理及代谢特性作了较详细的分析。结果表明,在己酸发酵过程中除产生正常代谢产物己酸外,还产生丁酸、乙酸、戊酸等其它酸类和甲烷,氢气和ＣＯ_２等气体。用１—^１３Ｃ－乙酸钠和未标记的乙醇作为底物发酵,用色质联用仪（ＧＣ／ＭＳ）分析,结果表明：在己酸合成中碳的来源为乙醇和乙酸,中间代谢产物为丁酸。     

Effects of exercise on mammary metabolism in the lactating ewe

Mammary metabolism in multiparous lactating ewes fed either lucerne chaff:barley grain (L:B; 70:30) or lucerne chaff:lupin grain (L:Lu; 70:30) diets was measured while at rest, during exercise on a treadmill at 0.7 m s⁻¹ on a 10 ° slope for 60 min, and during 30 min recovery from exercise. The effects of these treatments on plasma glucose, lactate, alpha-amino nitrogen (-amino N), non-esterified fatty acids (NEFA) and acetate were measured. Net mammary uptake of oxygen and metabolites was calculated from mammary blood flow and arteriovenous concentration (A − V) differences.

Mammary blood flow was reduced by 25% during exercise. Arterial concentrations of oxygen, glucose, lactate, -amino N and NEFA increased during exercise, whereas acetate concentration either remained unchanged or declined. Mammary A − V differences were significantly higher for oxygen, glucose, lactate and NEFA, and tended to be higher for -amino N and lower for acetate during exercise. The mammary uptakes of oxygen, glucose, lactate and -amino N were unaffected by exercise, whereas the uptake of NEFA was significantly increased and that of acetate was significantly reduced. The changes in arterial concentrations and mammary uptakes in response to exercise were not significantly affected by the diet. The responses in acetate and NEFA fluxes across the mammary gland might bring a change in the utilization of other metabolites as well as in the fatty acid composition of milk fat.     

Enzyme activity profiles in an overwintering population of freeze-tolerant larvae of the gall fly,Eurosta solidaginis

The activity of some enzymes of intermediary metabolism, including enzymes of glycolysis, the hexose monophosphate shunt, and polyol cryoprotectant synthesis, were measured in freeze-tolerant Eurosta solidaginis larvae over a winter season and upon entry into pupation. Flexible metabolic rearrangement was observed concurrently with acclimatization and development. Profiles of enzyme activities related to the metabolism of the cryoprotectant glycerol indicated that fall biosynthesis may occur from two possible pathways: 1. glyceraldehyde-phosphate glyceraldehyde glycerol, using glyceraldehyde phosphatase and NADPH-linked polyol dehydrogenase, or 2. dihydroxyacetonephosphate glycerol-3-phosphate glycerol, using glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase. Clearance of glycerol in the spring appeared to occur by a novel route through the action of polyol dehydrogenase and glyceraldehyde kinase. Profiles of enzyme activities associated with sorbitol metabolism suggested that this polyol cryoprotectant was synthesized from glucose-6-phosphate through the action of glucose-6-phosphatase and NADPH-linked polyol dehydrogenase. Removal of sorbitol in the spring appeared to occur through the action of sorbitol dehydrogenase and hexokinase. Glycogen phosphorylase activation ensured the required flow of carbon into the synthesis of both glycerol and sorbitol. Little change was seen in the activity of glycolytic or hexose monophosphate shunt enzymes over the winter. Increased activity of the -glycerophosphate shuttle in the spring, indicated by greatly increased glycerol-3-phosphate dehydrogenase activity, may be key to removal and oxidation of reducing equivalents generated from polyol cryoprotectan catabolism.Abbreviations 6PGDH 6-Phosphogluconate dehydrogenase - DHAP dihydroxy acetone phosphate - F6P fructose-6-phosphate - F6Pase fructose-6-phospha-tase - FBPase fructose-bisphosphatase - G3P glycerol-3-phosphate - G3Pase glycerol-3-phosphate phophatase - G3PDH glycerol-3-phosphate dehydrogenase - G6P glucose-6-phosphate - G6Pase glucose-6-phosphatase - G6PDH glucose-6-phosphate dehydrogenase - GAK glyceraldehyde kinase - GAP glyceraldehyde-3-phosphate - GAPase glyceraldehyde-3-phosphatase - GAPDH glyceraldehyde-3-phosphate dehydrogenase - GDH glycerol dehydrogenase - GPase glycogen phosphorylase - HMS hexose monophosphate shunt - LDH lactate dehydrogenase - NADP-IDH NADP⁺-dependent isocitrate dehydrogenase - PDHald polyol dehydrogenase, glyceraldehyde activity - PDHgluc polyol dehydrogenase, glucose activity - PFK phosphofructokinase - PGI phosphoglucoisomerase - PGK phosphoglycerate kinase - PGM phosphoglucomutase - PK pyruvate kinase - PMSF phenylmethylsulfonylfluoride - SoDH sorbitol dehydrogenase - V _max maximal enzyme activity - ww wet weight     

Differential expression of Alpha,Mu, and Pi classes of glutathione S-transferases in chemosensory mucosae of rats during development

The expression of three classes of glutathione S-transferases (GSTs), Alpha, Mu, and Pi was investigated in the nasal mucosae of rats during development using immunohistochemical methods. GST Alpha and Mu were first detected in the supranuclear region of sustentacular cells on embryonic days 16. The Bowman's glands expressed differential patterns of immunoreactivity during development, beginning at postnatal day (P) 2 and P6 for Alpha and Mu classes, respectively and being greatest at P11 for both. The acinar cells of vomeronasal glands in the vomeronasal organ expressed Alpha and Mu classes of GSTs from P11 onwards. In the septal organ of Masera, the supranuclear region of sustentacular cells expressed GSTs from P11 with little or no variation during development. In the respiratory mucosa, Alpha and Mu classes of GSTs were detected at the brush borders of ciliated cells and in the acinar cells of posterior septal glands, but not in anterior septal or respiratory glands located on the turbinates. Compared to olfactory mucosa, the changes in immunoreactivity for GSTs were less pronounced in the respiratory mucosa during development. Specific GST Pi immunoreactivity was not detected in the nasal mucosae at any stage of development studied. The occurrence of GSTs in the nasal mucosa, including olfactory, vomeronasal, septal, and respiratory epithelia, suggests that the GSTs are actively involved in the biotransformation of xenobiotics including odorants and pheromones, and may also participate in perireceptor processes such as odorant clearance. In addition, we have developed a working model describing the cellular localization of certain phase I (e.g., cytochrome P-450s) and phase II (e.g., GSTs, -glutamyl transpeptidase) biotransformation enzymes in the olfactory mucosa and their proposed roles in xenobiotic metabolism.     

Y-intercept of the maximal work-duration relationship and anaerobic capacity in cyclists

The degree to which the y-intercept (Y-int) of the linear regression of maximal work output on exercise duration represented anaerobic capacity was determined in ten well-trained male cyclists [peak oxygen uptake ( = 69.8 (SD 4.2) ml · kg ^–1 · min ^–1). Each cyclist performed three exhausting cycle sessions on separate occasions; the mean exercise durations were 312, 243 and 141 s for the low (approximately 104% , medium (approximately 108% and high (approximately 113% intensities respectively, and Y-int (kilojoules; joules per kilogram was derived from the regression of work output on exercise duration. The muscle anaerobic adenosine 5-triphosphate (ATP) yield (ATP) and anaerobic capacity (AC) were estimated from changes in metabolites in the vastus lateralis muscle and blood lactate concentration during the high intensity cycling session. The activities of glycogen phosphorylase, phosphofructokinase and citrate synthase, as well as muscle buffer value (in vitro ) were also determined. The Y-int (kilojoules) was positively correlated (P0.05) with AC (r=0.73), ATP (r=0.70) and in vitro (r=0.71); similar correlations (P0.05) were observed for Y-int (joules per kilogram). The Y-int was not correlated (P>0.05) with any enzyme activity. When the Y-int was transformed into oxygen equivalents [litres of oxygen equivalent (1 O₂ Eq)] it was, on average, 0.92 1 O₂ Eq lower than AC (P0.05); however, an alternative method of establishing the work-duration regression yielded a mean Y-int which was only 0.19 1 O₂ Eq less than AC (P0.05). These findings support the validity of Y-int as a work estimate of anaerobic capacity in well-trained cyclists.     

Intra- and interobserver concordance in scoring Harris lines: A test on bone sections and radiographs

Little attention has been devoted to assessing the reproducibility of (paleo)pathological observations. Harris lines (HL) are among the markers most used to determine chronology of stresses suffered during growth. Nevertheless, their scoring entails remarkable methodological difficulty. Bone sections (S) and radiographs (R) of 29 adult tibiae of archeological provenance (medieval) were scored for HL by five observers. At regular intervals of time, each observer gave two independent counts on both series. Results show a) a substantial interobserver disagreement of HL estimates for both sectional and radiographic records, and b) a high level of intraobserver error. © 1994 Wiley-Liss, Inc.     

The effect of homocysteine thiolactone and its alpha methylated derivative on bone matrix in the mouse

Summary Homocysteine (HC) is a radiation protector but toxic to bone. Its derivative homocysteine thiolactone (HCTL) and the alpha-alkylated analogue (A-methyl-HCTL) was fed to mice for a period of six weeks in a daily dose of 50 mg/kg body weight. Parameters for bone matrix as collagen content, acid solubility of bone collagen, urinary bone collagen cross links (pyridinolines) and urinary acid glycosaminoglycans were determined. Urinary acid glycosaminoglycans were significantly reduced in the HCTL treated group but not in the alpha-methyl-homocysteine thiolactone (A-methyl-HCTL) group (controls: 45 ± 7 mg/mmol creatinine, homocysteine thiolactone 38 ± 5 mg/mmol creatinine, A-methyl HCTL 45 ± 6 mg/mmol creatinine).No differences were found for the parameters of bone collagen between the groups. The potent radiation protecting methylated derivative therefore did not change bone matrix and should be a candidate for further toxicological studies.     

Circulating concentrations of interleukin-6 in cancer patients and their pathogenic role in tumor-induced hypercalcemia

Circulating interleukin-6 (IL-6) concentrations correlate with disease activity in severe inflammatory conditions, in sepsis and in some hematological malignancies. On the other hand, IL-6 is a potent stimulator of osteoclastogenesis and has been implicated as a contributory factor in the genesis of osteopenic conditions. We measured circulating IL-6 levels by a sensitive (detection limit of 10 U/ml) and specific bioassay in 103 patients with advanced cancer, including 41 with tumor-induced hypercalcemia before any specific hypocalcemic therapy. We related IL-6 concentrations to clinical features and to biochemical parameters of bone metabolism, including blood Ca, Ca²⁺, P_i, intact parathyroid hormone, parathyroid hormone-related protein, osteocalcin, 1,25-(OH)₂-vitamin D and, as markers of bone resorption, the fasting urinary excretion of calcium (Ca/creatinine) and hydroxyproline. IL-6 levels were increased, i.e. detectable, in 23% of the patients, 8/41 (20%) hypercalcemic and 16/62 (26%) normocalcemic patients (NS); the distribution of the values was similar in the two groups. The presence of increased IL-6 concentrations was not related to any clinical characteristic, notably not to the survival nor to the existence of bone metastases, whether in hypercalcemic or normocalcemic patients; e.g., only 3/12 (25%) hypercalcemic subjects without bone metastases had elevated IL-6 levels. We found no significant correlations between IL-6 concentrations and any of the biochemical parameters studied. Hypercalcemic subjects with increased IL-6 had higher urinary Ca/creatinine levels than patients with normal IL-6 levels (P<0.005) but this was not the case in normocalcemic subjects. Mean concentrations of inflammatory or other bone metabolism markers were not significantly different between patients with normal or with elevated IL-6 levels. In summary, circulating IL-6 levels were increased in 23% of 103 patients with advanced cancer, but the frequency of increased IL-6 concentrations was not related to the presence of hypercalcemia or to any marker of calcium metabolism or bone turnover. The pathogenic importance of circulating IL-6 in patients with solid tumors remains to be demonstrated and our data indicate that increased circulating levels of IL-6, possibly reflecting the activation of the immune system, only contribute in a minor way to the osteolytic process in patients with tumor-induced hypercalcemia.