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991.
A cross-sectional survey was made in 56 exceptionally healthy males, ranging in age from 20 to 84 years. Measurements were made of selected steroidal components and peptidic hormones in blood serum, and cognitive and physical tests were performed. Of those blood serum variables that gave highly significant negative correlations with age (r > -0.6), bioavailable testosterone (BT), dehydroepiandrosterone sulfate (DHEAS), and the ratio of insulin-like growth factor 1 (IGF-1) to growth hormone (GH) showed a stepwise pattern of age-related changes most closely resembling those of the age steps themselves. Of these, BT correlated best with significantly age-correlated cognitive and physical measures. Because DHEAS correlated well with BT and considerably less well than BT with the cognitive and physical measures, it seems likely that BT and/or substances to which BT gives rise in tissues play a more direct role in whatever processes are rate-limiting in the functions measured and that DHEAS relates more indirectly to these functions. The high correlation of IGF-1/GH with age, its relatively low correlation with BT, and the patterns of correlations of IGF-1/GH and BT with significantly age-correlated cognitive and physical measures suggest that the GH-IGF-1 axis and BT play independent roles in affecting these functions. Serial determinations made after oral ingestion of pregnenolone and data from the literature suggest there is interdependence of steroid metabolic systems with those operational in control of interrelations in the GH-IGF-1 axis. Longitudinal concurrent measurements of serum levels of BT, DHEAS, and IGF-1/GH together with detailed studies of their correlations with age-correlated functional measures may be useful in detecting early age-related dysregulations and may be helpful in devising ameliorative approaches.  相似文献   
992.
The Gp31 protein from bacteriophage T4 functionally substitutes for the bacterial co-chaperonin GroES in assisted protein folding reactions both in vitro and in vivo. But Gp31 is required for the folding and/or assembly of the T4 major capsid protein Gp23, and this requirement cannot be satisfied by GroES. The 2.3 A crystal structure of Gp31 shows that its tertiary and quaternary structures are similar to those of GroES despite the existence of only 14% sequence identity between the two proteins. However, Gp31 shows a series of structural adaptations which will increase the size and the hydrophilicity of the "Anfinsen cage," the enclosed cavity within the GroEL/GroES complex that is the location of the chaperonin-assisted protein folding reaction.  相似文献   
993.
We report on preoperative estimation of operative risk, principally rating liver injury in chronic liver disease, c.g., chronic hepatitis and cirrhosis, for liver resection and general surgery. Regarding general surgery, elective and standard operation are possible in Child A and operations with measures to lessen intraoperative blood loss and lymphadenectomy in Child B, but in Child C, surgery is limited to emergency palliative operations, and conservative treatment methods must chosen. In liver resection and major surgery it is important to estimate extent of liver resection and operative risk, primarily by R15 and KICG, and make an overall judgment based on fibronectin, hyaluronic acid, sinusoidal endothelial cell function measured by thrombomodulin, sigma IRI in the 75g OGTT, Fischer's ratio and other indices of lipid metabolism. Generally, surgery limits are: KICG, 40%. Conventional indices of hepatic reserve should be reviewed. Indices recently attracting interest in liver resection cases are quantitative 99mTC-galactosyl human serum albumin scintigraphy using liver cell surface asialoglycoprotein receptor, and functional hepatic resection rate using 99mTC-GSA SPECT images, which is important in estimating liver regeneration after percutaneous trashepatic portal embolization.  相似文献   
994.
A group of 7,8-(methylenedioxy)-1-phenyl-3,5-dihydro-4H-2, 3-benzodiazepin-4-ones was synthesized and assayed for antagonism of rat brain alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors expressed in Xenopus oocytes. The benzodiazepinones inhibited AMPA-activated membrane current responses in a manner consistent with noncompetitive, allosteric inhibition of the receptor-channel complex. The most potent compound in the series was 1-(4-aminophenyl)-7,8-(methylenedioxy)-3,5-dihydro-4H-2, 3-benzodiazepin-4-one (6), which had an IC50 of 2.7 microM. For comparison, the reference compound GYKI 52466 (2) had an IC50 of 6.9 microM. Compound 6 also had potent anticonvulsant activity in a mouse maximum electroshock-induced seizure (MES) assay: the ED50 was 2.8 mg/kg iv, whereas the ED50 for GYKI 52466 was 4.6 mg/kg iv. In contrast to a previous report, the 7,8-dimethoxy analogue of 6 was a low-potency AMPA antagonist (IC50 >100 microM) and weak anticonvulsant (ED50 >10 mg/kg iv). The benzodiazepinones described herein are potent noncompetitive AMPA receptor antagonists that could have therapeutic potential as anticonvulsants and neuroprotectants.  相似文献   
995.
CRH and POMC-derived peptides are produced at a number of intrauterine sites in both the nonpregnant and pregnant states. It is hypothesized that CRH and POMC-derived peptides may be produced locally by the uterus to modulate myometrial contractility. This study has examined the distribution of these peptides in human uterine tissue during the ovulatory cycle and pregnancy. The immunoperoxidase staining method was used to localize CRH and POMC-derived peptides: ACTH, beta-endorphin, and alphaMSH. Immunoreactive (IR-) CRH and IR-POMC-derived peptides, beta-endorphin and alphaMSH, were observed in the myometrial smooth muscle, vascular smooth muscle, endometrial glandular epithelium, and luminal epithelium of the nonpregnant uterus (n = 17). Staining for IR-CRH did not change during the cycle from the proliferative (n = 8) to the secretory phases (n = 9). Conversely, staining for IR-beta-endorphin and IR-alphaMSH was only observed during the secretory phase of the cycle (n = 9). In uterine tissue obtained from pregnant women (n = 20) IR-CRH was present in the myometrial smooth muscle, vascular smooth muscle, decidua, and glandular epithelium. IR-POMC-derived peptides were not detectable at any uterine site during pregnancy (n = 20). IR-CRH was measurable in myometrial extracts collected from pregnant women undergoing cesarean section (20.9+/-3.8 ng/g wet wt; n = 7) and from nonpregnant premenopausal women undergoing hysterectomy (7.7+/-2.1 ng/g wet wt; n = 6). IR-CRH concentrations significantly increased with pregnancy. Levels of messenger ribonucleic acid encoding for CRH were examined in nonpregnant (n = 4) and pregnant (n = 10) myometrial smooth muscle and were also significantly increased with pregnancy. This study has demonstrated that levels of CRH and POMC peptide in human uterine tissue change with pregnancy and that CRH is produced locally by myometrial smooth muscle cells. These studies are consistent with the possibility that the CRH peptide has an autocrine/paracrine activity during pregnancy and labor that may be related to the modulation of myometrial contractility.  相似文献   
996.
Hysteresis of the nasal airway pressure-flow relationship (PFR) is seen during hyperpnea, with lower nasal resistance during increasing inspiratory flow than during decreasing flow. We hypothesized that the nasal PFR hysteresis arose in the nasal vestibule airway because of progressive collapse during the inspiration. We measured the inspiratory transnasal and transvestibular PFR for one nasal passage in five normal subjects breathing via a nasal mask during voluntary hyperventilation, both with voluntary nostril flaring and without flaring. The inspiratory hysteresis (IH) was quantified as the ratio of the areas under the descending and ascending pressure-flow curves. Flaring reduced the vestibular IH from 1.96 +/- 0.06 to 1.15 +/- 0.06 and the nasal IH from 2.05 +/- 0.13 to 1.28 +/- 0.06 (both P < 0.01). Our results demonstrate that hysteresis arises in the compliant vestibule segment of the nasal airway, likely because of progressive collapse of the nasal vestibule during inspiration. The findings suggest that hysteresis is prevented by voluntary nostril flaring maintained throughout inspiration.  相似文献   
997.
India ink and radioactive 51Cr-labeled microspheres were used in separate trials to examine the role of the yolk stalk lumen as a distinct pathway between the yolk sac and gut through the first 5 d of posthatch growth in broiler chicks. Throughout this period, India ink was able to pass from the yolk sac through the yolk stalk and into the intestine, but was not able to pass from the intestine into the yolk stalk or yolk sac. Furthermore, labeled microspheres moved from the yolk sac via the yolk stalk into the gut; which caused the total counts per minute of the intestine, yolk stalk, and excreta to progressively increase. It was concluded that India ink and 51Cr-labeled microspheres were useful materials in establishing that the yolk stalk provides a direct one-way passage by which material in the yolk sac may move into the intestine of broiler chicks during the first 5 d after hatching.  相似文献   
998.
When alpha-hydroxytamoxifen (alpha-OHTAM) was incubated with rat liver hydroxysteroid (alcohol) sulfotransferase a (STa) and 3'-phosphoadenosine 5'-phosphosulfate, (E)-alpha-OHTAM was found to be a better substrate for STa than (Z)-alpha-OHTAM. To explore the formation of tamoxifen (TAM)-derived DNA adducts, DNA was incubated with STa and either (E)-alpha-OHTAM or (Z)-alpha-OHTAM in the presence of 3'-phosphoadenosine 5'-phosphosulfate. Using 32P-postlabeling analysis, the amount of TAM-DNA adducts resulting from (E)-alpha-OHTAM was 29 times higher than that observed with (E)-alpha-OHTAM alone. Using (Z)-alpha-OHTAM and STa, some TAM-DNA adducts were also detected but at levels 6.5 times lower than that observed with (E)-alpha-OHTAM and STa. When compared with standards of stereoisomers of 2'-deoxyguanosine 3'-monophosphate-N2-tamoxifen, the major tamoxifen adduct was identified chromatographically as an epimer of the trans form of alpha-(N2-deoxyguanosinyl)tamoxifen, and the minor adduct was identified as an epimer of the cis form. In the reaction mixture, a conversion from (E)-alpha-OHTAM to (Z)-alpha-OHTAM through the carbocation intermediate was also detected. These results show that sulfation of alpha-OHTAM catalyzed by STa results in the formation of TAM-DNA adducts.  相似文献   
999.
The proliferative response of human lymphocytes to stimuli such as foreign histocompatibility antigens or mitogens is generally assessed by measuring the amount of tritiated thymidine which the cells incorporated in culture. In this paper, the possibility of assessing lymphocyte proliferation and viability by an empirical assay, using measurement of light absorbance on a ELISA reader in the yellow wave length (450 nm/air-550 nm/air), has been studied. The correlation of these measurements with a colormetric viability assay using MTS/PMS, with tritiated thymidine incorporation and with trypan blue exclusion viability counting, was determined. The results showed that the light absorbance assay correlated well with cell proliferation during 48-120 hours culture period and with cell viability after a 72 hour period. The MTS/PMS colormetric assay as well as trypan blue exclusion cell counting confirmed that the light absorbance assay was not merely caused by dead cells. This data confirm that the light absorbance assay is sufficiently sensitive to low levels of proliferation to allow detection of such responses at least as effectively as thymidine incorporation. The light absorbance assay procedure avoids the expense, time and hazards associated with scintillation counting, and is simple to perform without the necessity for reagents and preparative steps required by other assays.  相似文献   
1000.
The myocardium of the left ventricle of the heart is a fibrous structure, the fibres being wound helically anticlockwise on the epicardium and changing progressively through the wall thickness to being wound helically clockwise on the endocardium. At any point, therefore, the material can be considered as transversely isotropic. For mechanically modelling the ventricle, two independent material properties, the along-fibre and across-fibre moduli of elasticity are required. This paper describes a computer method for determining these by using a finite element model and matching cavity volume and ventricle length against values derived from cineangiographic and pressure data. The method is applied to a group of patients with various cardiac diagnoses and the modular ratios for their myocardia are derived.  相似文献   
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