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1.
Conventional studies on bracken fern (Pteridium aquilinum; PA) carcinogenicity have used high dietary concentrations (around 30%) and long-term exposure (up to 52-70 weeks) without consideration of the multistep character of the chemical carcinogenesis process. The present study evaluated specifically the promoting potential of 3-5% dietary crude PA in the rat urinary bladder mucosa in a 32-week-long initiation-promotion assay for chemical carcinogenesis. Initiation of urothelial carcinogenesis was accomplished with N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN). Uracil (U) was provided through the diet in order to expand the population of initiated cells. Seven groups (G) of male Wistar rats were submitted to the following treatments: G1 = BBN (n = 8); G2 = U (n = 10); G3 = BBN-U (n = 9); G4 = BBN-PA-U-PA (n = 16); G5 = PA (n = 8); G6 = BBN-PA (n = 10); G7 = PA-U-PA (n = 12). At the end of the experiment rats presenting epithelial papillary or nodular hyperplasia (PNH), papillomas (PAP), or simultaneous PNH plus PAP numbered, respectively G1: 2-0-1; G2: 0-0-0; G3: 3-0-2; G4: 4-3-2; G5: 1-0-1; G6: 8-0-0; and G7: 0-0-0, with no significant differences in the incidence of lesions among the groups. More frequent and more severe lesions occurred in BBN-initiated animals, predominantly in those also exposed to uracil (G3 and G4). Low-dose crude bracken fern in the diet does not promote rat urinary bladder carcinogenesis after a 32-week period of exposure, even when the initiated urothelial cell population has been expanded through a mechanical stimulus.  相似文献   

2.
Heterotrimeric G proteins of the Gq class have been implicated in signaling pathways regulating cardiac growth under physiological and pathological conditions. Knockout mice carrying inactivating mutations in both of the widely expressed G alpha q class genes, G alpha q and G alpha 11, demonstrate that at least two active alleles of these genes are required for extrauterine life. Mice carrying only one intact allele [G alpha q(-/+);G alpha 11(-/-) or G alpha q(-/-);G alpha 11(-/+)] died shortly after birth. These mutants showed a high incidence of cardiac malformation. In addition, G alpha q(-/-);G alpha 11(-/+) newborns suffered from craniofacial defects. Mice lacking both G alpha q and G alpha 11 [G alpha q(-/-);G alpha 11(-/-)] died at embryonic day 11 due to cardiomyocyte hypoplasia. These data demonstrate overlap in G alpha q and G alpha 11 gene functions and indicate that the Gq class of G proteins plays a crucial role in cardiac growth and development.  相似文献   

3.
Four stains designated as OB94-1 to OB94-4 of group A bovine rotavirus (BRV) were isolated from 35 fecal samples of calves with diarrhea in sporadic outbreaks. In VP7 (G) and VP4 (P) serotyping of these isolates, OB94-1 to OB94-3 were determined as G6P5, G6P5 and G10P5, respectively, by cross neutralization (NT) test and the G- and P- serotyping polymerase chain reaction (PCR) analysis. OB94-4 showed a one-way antigenic relation with the Lincoln stain (G6P1) and a weak antigenic relationship with the KK3 strain (G10P11), and was determined as G6P11 by the PCR method. Thus, OB94-4 was shown to be a new G6 BRV with different antigenic properties from the others in the NT test.  相似文献   

4.
The function of the hypothalamic-pituitary-adrenal axis as related to the degree of severity of a septic process was assessed by measuring plasma levels of beta-endorphin, ACTH and cortisol. Sixty-one cases of postoperative patients treated at the intensive care unit were classified into four groups according to the severity of infection: Group 1 (control) included patients who did not show any sign of infection, group 2 patients with sepsis, group 3 patients with septic syndrome and group 4 patients with septic shock. Compared to G1 patients' ACTH values (4.16+/-2.6pg/ml), a statistically significant increase in ACTH values in various stages of septicemia (p < 0.005) with a noticeable difference also between G3 (7.11 +/-3.7pg/ml) and G4 (11.5+/-6.6pg/ml) (p<0.05) was found. Differences were also observed in beta-endorphin (with a level of significance between the several groups of p = 0.0001). Also, beta-endorphin values in G4 (40.6+/-30.3 pg/ml) differed significantly from each of G1 (17.5 +/-6.6 pg/ml), G2 (21.1+/-11.3 pg/ml) and G3 (23.5+/-12 pg/ ml) (p<0.05). A progressive hypercortisolemia was obvious, with values of G4 (37.2+/-15.6 microg/dl) differing significantly from those of G1 (18+/-4.6microg/dl) and G2 (24-/+8.4microg/dl) (p<0.05) and of G3 (28.5+/-12.3 microg/dl) from that of G1 (p < 0.05). Interestingly, a dissociation of ACTH, beta-endorphin and cortisol was observed, in that the increased values of beta-endorphin and cortisol, detected in the G3 were not associated with a parallel increase in ACTH. These findings might be interpreted in the sense of an impairment of the stress stimulation of the hypothalamic pituitary adrenal axis. Provided that such a situation can be lethal, our results further confirm the idea that a low-dose, steroid replacement might be beneficial to critical illness.  相似文献   

5.
Helicobacter pylori infection increases the serum concentration of gastrin, and this may be one of the mechanisms by which it predisposes to duodenal ulceration. Different forms of circulating gastrin were studied both basally and postprandially in 13 duodenal ulcer patients before and one month after eradication of H pylori. Three antisera that are specific for particular regions of the gastrin molecules were used. Gel chromatography indicated that > 90% of the circulating gastrin consisted of gastrin (G) 17 and G34 both before and after eradicating the infection. The basal median total immunoreactive gastrin concentration fell from 26 pmol/l (range 11-43) to 19 pmol/l (8-39) (p < 0.05), entirely because of a fall in G17 from 6 pmol/l (< 2.4-25) to < 2.4 pmol/l (< 2.4-23) (p < 0.001). The median (range) basal G34 values were similar before (15 pmol (2-36)) and after (10 pmol (2-30)) eradication. The median total immunoreactive gastrin concentration determined 20 minutes postprandially fell from 59 pmol/l (38-114) to 33 pmol/l (19-88) (p < 0.005), and again this was entirely the result of a fall in G17 from 43 pmol/l (9-95) to 17 pmol/l (< 2.4-52) (p < 0.001). The median postprandial G34 values were similar before (13 pmol/l, range 6-42) and after (15 pmol/l, range 6-30) eradication. Eating stimulated a noticeable rise in G17 but little change in G34, both in the presence and absence of H pylori. The finding that H pylori infection selectively increases G17 explains why the infection causes mainly postprandial hypergastrinaemia. G17 is increased selectively because H pylori predominantly affects the antral mucosa which is the main source of G17 whereas G34 is mainly duodenal in origin. This study also indicates that the increased concentration of gastrin in H pylori infection is the result of an increase in one of the main biologically active forms of the hormone.  相似文献   

6.
Replies to the commentaries by R. G. Tweed, L. G. Conway, III, and Andrew G. Ryder (see record 1999-11644-006), T. L. Holdstock (see record 1999-11644-007), and R. J. Smith (see record 1999-11644-008) on Hermans and Kempen's article (see record 1998-12442-002) on the issues of globalization and localization in cross cultural psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

7.
We measured intrapulmonary deposition of 0. 5-, 1-, 2-, and 3-micron-diameter particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and at approximately 1.6 G. Subjects breathed aerosols at a constant flow rate (0.4 l/s) and tidal volume (0.75 liter). At 1 G and approximately 1.6 G, deposition increased with increasing particle size. In microG, differences in deposition as a function of particle size were almost abolished. Deposition was a nearly linear function of the G level for 2- and 3-micron-diameter particles, whereas for 0.5- and 1.0-micron-diameter particles, deposition increased less between microG and 1 G than between 1 G and approximately 1.6 G. Comparison with numerical predictions showed good agreement for 1-, 2-, and 3-micron-diameter particles at 1 and approximately 1.6 G, whereas the model consistently underestimated deposition in microG. The higher deposition observed in microG compared with model predictions might be explained by a larger deposition by diffusion because of a higher alveolar concentration of aerosol in microG and to the nonreversibility of the flow, causing additional mixing of the aerosols.  相似文献   

8.
The connection between lipids and the rate of progression of chronic renal disease was retrospectively examined in 70 patients who were divided into 2 groups according to their baseline creatinine clearance (CCr): Group 1 (Gp1) contained 30 patients with CCr 60-40 mL/min followed for 40.0 +/- 13.3 months; Group 2 (G2) contained 40 patients with CCr 39-15 mL/min followed for 39.0 +/- 18.2 months. The following parameters were considered: basal and final CCr proteinuria per unit of CCr (UProt/CCr); the difference between final and basal UProt/CCr (delta UProt/CCr); the change in CCr/month (delta CCr); baseline triglycerides (TG), total (TC), HDL (HDLC) and LDL (LDLC) cholesterol, Apo AI, Apo B, Lp(a). Besides in basal CCr the 2 groups significantly differed in the final CCr, final UProt/CCr, delta UProt/CCr, delta CCr. No differences were observed concerning lipid parameters except for Lp(a) (G1 14.8 +/- 13.6, G2 28.7 +/- 27.4 mg/dL; p < 0.05). Baseline TG (G1 184.1 +/- 61.3, G2 187.5 +/- 72.1 mg/dL) and Apo B (only G2 1.05 +/- 0.32 g/L) were significantly higher than normal subjects and the Apo AI/Apo B ratio (G1 1.42 +/- 0.43, G2 1.33 +/- 0.45) were significantly lower than in normal subjects. delta CCr, while inversely correlated in both groups with delta UProt/CCr (p < 0.01), only in G2 did it correlate directly with the Apo AI/Apo B ratio (p < 0.05) and inversely with Apo B and LDLC (p < 0.05). Although a correlation between Lp(a) and delta CCr was not found, 20/22 patients (3/5 G1, 17/17 G2) with a level > 30 mg% ran a progressive course. A natural progression of CRI, heralded by an increasing UProt, is highly frequent when baseline CCr is < 40 mL/min; only then lipids seem to add a burden to the renal damage.  相似文献   

9.
A single-chain Fv (sFv) was expressed from the variable regions of the CD40-specific mAb G28-5. The molecule bound CD40 with a high affinity (2.2 nM) and was a monomer in solution. Surprisingly, G28-5 sFv was a potent CD40 agonist that rapidly crosslinked CD40 on the cell surface but did not crosslink CD40-Ig in solution. G28-5 sFv was a more potent agonist than G28-5 IgG and was able to stimulate CD40 responses by B cells and monocytes. G28-5 IgG partially blocked, whereas G28-5 sFv augmented CD40 responses during stimulation with natural ligand (gp39-CD8 fusion protein). These results indicate that the functional activity of ligands built from the binding site of G28-5 is highly dependent upon the size and physical properties of the molecule both in solution and on the cell surfaces.  相似文献   

10.
Previous studies showed that alpha-adrenoceptor (AR) stimulation with norepinephrine is more potent at eliciting contraction in aortas from 1-month-old Fischer 344 rats than from older rats and that this response is mediated by alpha 1b- and alpha 1d-AR subtypes in 1-month-old rats. We examined the G proteins responsible for alpha 1-AR-mediated contractile response and inositol phosphate accumulation in the aortas of 1-month-old Fischer 344 rats. Pertussis toxin (PTX) treatment (2.5 micrograms/ml for 4 hr) of aortic rings partially inhibited phenylephrine (PHE)-stimulated contraction and inositol phosphate accumulation, suggesting the involvement of PTX-sensitive and -insensitive G proteins. Specific antisera directed against G alpha q and G alpha o but not G alpha s and G alpha i precipitated specific alpha 1-AR binding sites labeled with 2-[beta-(4-hydroxy-3-[125I]iodophenyl)ethylaminomethyl]tetralone. The number of 2-[beta-(4-hydroxy-3-[125I]iodophenyl)ethylaminomethyl]tetralone binding sites precipitated by G alpha proteins was increased by activating membrane alpha 1-ARs with PHE. Moreover, PHE stimulated the palmitoylation of G alpha q and G alpha o, and this response was blocked by the alpha 1-AR antagonist prazosin. Characterization of the alpha 1-AR subtypes that couple to G proteins indicates that although aortic alpha 1a-, alpha 1b-, and alpha 1d-ARs were associated with G alpha q, alpha 1b-AR was also linked to G alpha o. These results suggest that alpha 1-ARs mediate the contractile response in rat aorta by coupling to both Gq protein and the PTX-sensitive G(o) protein.  相似文献   

11.
12.
As a role for oxygen free radicals has been suggested in gentamicin (G) nephrotoxicity, we tested the hypothesis that exogenously administered glutathione (GSH), able to restore intracellular antioxidant potential, could be useful in reducing damage. Adult Sprague-Dawley rats were injected with saline (n = 30), subcutaneous (s.c.) G 100 (n = 23) and 150 mg/kg/day (n = 14), or s.c. G at the same dosages plus intraperitoneal (i.p.) GSH 1200 mg/kg/day (n = 24 and 14, respectively) for 7 days. In the G-100-day protocol, GSH-treated rats showed significantly lower renal G content (2.79 +/- 0.8 vs. 3.61 +/- 1.4 micrograms/mg prot) coupled with lower plasma urea (153 +/- 79 vs. 188 +/- 61 mg/dL) and creatinine levels (1.63 +/- 1 vs. 2.45 +/- 1 mg/dL). As to renal oxidant/antioxidant balance, local GSH was increased (0.32 +/- 0.01 vs. 0.19 +/- 0.01 microgram/mg prot) while lipid peroxidation, determined by production of thiobarbituric acid reactive substances (TBARS), was decreased (0.35 +/- 0.02 vs. 0.52 +/- 0.02 nmol/mg prot). In the G-150-mg protocol, GSH-treated rats showed no differences in renal gentamicin content or in blood urea and creatinine levels, in spite of a significantly lower renal TBARS production and a significantly higher GSH content. Urine enzyme excretion did not significantly change in GSH-treated vs. not-GSH-treated rats in both protocols. We conclude that: (a) GSH interferes with G nephrotoxicity mainly via a reduction in G uptake; (b) the oxidative renal stress is not crucial in inducing renal damage. In fact, when increased G dosages blunt the ability of GSH in reducing G uptake, no substantial protection is demonstrated.  相似文献   

13.
14.
Addresses interpretive questions raised in articles by C. Maslach (see record 1980-30451-001) and by G. D. Marshall and P. G. Zimbardo (see record 1980-29870-001) concerning the present authors' (see record 1963-06064-001) 2-factor model of emotion. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

15.
BACKGROUND: Acidic beverages may be involved in regulating the cell proliferation of the gastric mucosa. We therefore analyzed the interaction of Coca-Cola consumption and gastric mucosal proliferation by means of flow cytometry. METHODS: Sixteen healthy students agreed to participate in this study. All volunteers underwent an oesophagogastroduodenoscopy after a 12-h overnight fast. Endoscopic changes in the gastric mucosa were determined quantitatively. One day later, after a 12-h overnight fast, all volunteers received standard Coca-Cola (200 ml, pH 2.6, 4 degrees C). One hour later all volunteers again underwent oesophagogastroduodenoscopy, to measure gastric mucosal damage. During both the first and the second endoscopy at least four biopsy specimens were taken from the antrum for flow cytometric analysis. RESULTS: The endoscopic analysis showed that there was no difference before and after Coca-Cola consumption. However, the flow cytometric analysis showed that Coca-Cola inhibited the proliferation index and the S phase. Before Coca-Cola consumption G0/G1: 60 (57-62), G2/M: 0.6 (0.2-1), S: 40 (37-42), and PI: 0.40 (0.38-0.43) and after Coca-Cola consumption G0/G1: 70 (60-73), G2/M: 1.9 (1.2-2.5), S: 28 (26-32), and PI: 0.30 (0.27-0.34) the cell population G0/G1 and G2/M phases were significantly increased (P < 0.0001, 0.0003), and the cell population S and PI phases were significantly low compared with the pre-consumption data (P < 0.0002, 0.0001). CONCLUSION: The cell cycle analysis reflects that Coca-Cola inhibits a crucial event in the cell cycle occurring at the G1/S border.  相似文献   

16.
1. In the present study we tested the hypothesis that insulin-like growth factor-1 (IGF-1) modulates resting chloride conductance (G(Cl)) of rat skeletal muscle by activating a phosphatase and that the chloride channel, based on the activity of phosphorylating-dephosphorylating pathways, has different sensitivity to specific ligands, such as the enantiomers of 2-(p-chlorophenoxy) propionic acid (CPP). 2. For this purpose G(Cl) in EDL muscle isolated from adult rat was first lowered by treatment with 5 nM 4-beta-phorbol 12,13 dibutyrate (4-beta-PDB), presumably activating protein kinase C (PKC). The effects of IGF-1 and of the enantiomers of CPP on G(Cl) were then tested. 3. IGF-1 (3.3 nM) had no effect of G(Cl) on EDL muscle fibres in normal physiological solution, whereas it completely counteracted the 30% decrease of G(Cl) induced by 4-beta-PDB. No effects of IGF-1 were observed on G(Cl) lowered by the phosphatase inhibitor okadaic acid (0.25 microM). 4. Ceramide, reported to activate on okadaic acid-sensitive phosphatase, mimicked the effects of IGF-1. In fact, N-acetyl-sphingosine (2.5-5 microM), not very effective in control conditions, increased the G(Cl) lowered by the phorbol ester, but not the G(Cl) lowered by okadaic acid. 5. In the presence of 4-beta-PDB, G(Cl) was differently affected by the enantiomers of CPP. The S(-)-CPP was remarkably less potent in producing the concentration-dependent reduction of G(Cl), whereas the R(+)-CPP caused an increase of G(Cl) at all the concentrations tested. 6. In conclusion, the PKC-induced lowering of G(Cl) is counteracted by IGF-1 through an okadaic acid sensitive phosphatase, and this effect can have therapeutic relevance in situations characterized by excessive channel phosphorylation. In turn the phosphorylation state of the channel can modulate the effects and the therapeutic potential of direct channel ligands.  相似文献   

17.
Bass (see 31: 2534) "obtained a correlation of - .20 between the California F scale and an F scale rewritten so that the content of each item reflected a viewpoint opposed to the original (called the G scale). Bass used this correlation in a factor analysis of the F and G scales, placing reliabilities in the diagonals… . However, the notation for the factor matrix… was in terms of F and G, not F and - G. Since the factor loadings… reproduce a correlation of rFG = + .20, the factor matrix labels should read F and - G… . necessitating a reversal in interpretation." (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

18.
The authors reassert the need for methodological changes in depression research appearing in the Journal of Personality and Social Psychology and other personality and social psychology journals. In this rejoinder the authors update their earlier literature review (H. Tennen, J. Hall, & G. Affleck; see record 1995-31710-001) and respond to the commentaries by P C. Kendall and E. C. Flannery-Schroeder (see record 1995-31700-001) and G. Weary, J. A. Edwards, and J. A. Jacobson (see record 1995-31713-001). The authors notice that G. Weary et al.'s own findings demonstrate the need to change how depression is measured and participants are assigned to experimental groups. The authors also challenge G. Weary et al.'s contention that structured interviews are limited because they require interviewer judgments, and they urge personality and social psychologists to learn more about these interviews. Finally, G. Weary et al.'s suspicion that depression research guidelines reflect professional parochialism is disputed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

19.
OBJECTIVE: To examine the relationship between plasma plasminogen activator inhibitor 1 (PAI-1) activity and PAI-1 gene (4G/5G) polymorphism and diabetic retinopathy in Pima Indians with type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied 171 Pima Indians with type 2 diabetes between the ages of 30-70 years in a population-based epidemiological survey. Plasma PAI-1 activity was measured by a spectrophotometric assay and PAI-1 4G/5G promoter genotype by the polymerase chain reaction (PCR) using allele-specific primers. Retinopathy was assessed by ophthalmoscopy after pupillary dilation and classified as any retinopathy or as nonproliferative and proliferative. RESULTS: Retinopathy was present in 70 (41%) subjects, and 4 (2.3%) subjects had proliferative retinopathy. Plasma PAI-1 activity was not significantly different among subjects with and without retinopathy (17.1 +/- vs. 19.7 +/- 9.1 arbitrary units (AU)/ml, P = 0.09). PAI-1 activity was negatively correlated with duration of diabetes (rs = -0.18, P = 0.02). In a logistic regression analysis controlled for age, sex, BMI, and duration of diabetes, any retinopathy was significantly associated with fasting plasma glucose concentrations (P < 0.05), 2-h postload glucose (P = 0.02), and HbA1c (P = 0.008), but not with PAI-1 activity (P = 0.48). The prevalence of retinopathy in the three genotype groups differed significantly (4G/4G, 4G/5G, and 5G/5G were 44, 49, and 24%, respectively; chi 2 = 8.22, df = 2, P = 0.016) and remained significant after controlling for age, sex, BMI, duration of diabetes, glycated hemoglobin, and urine albumin-to-creatine ratio in a logistic regression analysis. The odds ratios for retinopathy in subjects with 4G/4G and 4G/5G, compared with the 5G/5G genotype, were 2.0 and 3.1, respectively. CONCLUSIONS: Although diabetic retinopathy in Pima Indians with type 2 diabetes is not associated with PAI-1 activity, subjects with the 4G/4G and 4G/5G genotype had a higher prevalence of retinopathy compared with 5G/5G PAI-1genotype. These preliminary findings indicate that in Pima Indians with type 2 diabetes, presence of the 4G allele of the PAI-1 gene was associated with a higher risk of diabetic retinopathy.  相似文献   

20.
The enhancing effect of o-vanillin (2-hydroxy-3-methoxybenz-aldehyde) on mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was characterized with mutational specificity. The mutational spectrum of MNNG-induced mutations in the presence of o-vanillin was compared with that in the absence of o-vanillin by means of a series of mutant lacZ genes in E. coli that can detect each of the six types of base substitutions and five kinds of frameshift events. In the absence of o-vanillin, the mutational spectrum induced by MNNG consisted mainly of G.C-->A.T transitions and, to a lesser extent, -1(G.C) frameshift mutations. By adding o-vanillin at 75 micrograms/plate, a marked enhancement was observed in two transitions, G.C-->A.T and A.T-->G.C, and in two frameshift mutations, +1(G.C) and -1(G.C). Only a small change was observed in the -2(C.G-G.C) fraction. Regarding the MNNG-induced frameshifts at the A.T base pair, the +1(A.T) frameshift was much more enhanced by o-vanillin than the -1(A.T) frameshift.  相似文献   

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