Thyroxine-induced activation of hypothalamo-hypophysial axis in neotenic salamander larvae

Thyroxine injected into the hypothalamus of neotenic Ambystoma tigrinum induces metamorphosis by activating hypothalamo-hypophysial stimulatory control of thyroid activity, thereby removing the hypothalamic block to metamorphosis.     

巨磁电阻读出磁头

用巨磁电阻（GMR）材料构成的磁电子学新器件,已开始在计算机存储领域成功地获得了应用,本文介绍了用于计算机硬件磁盘驱动器的巨磁电阻磁头,描术字它的工作原理、性能特点及研究现状和发展趋势。     

An analysis of automatic teller machine usage by older adults: a structured interview approach

Sex differences in the activity of aromatase cytochrome P450 (CYP19) in the rat brain have been reported during pre- and postnatal development. It is unclear, however, whether these differences are reflected by corresponding differences in specific mRNA levels. To address this question, we have examined aromatase mRNA levels in specific regions of male and female rat brains by means of in situ hybridization (ISH). At prenatal stages of development, i.e. at gestational day 18 (GD18) and GD20, aromatase mRNA was detected in several preoptic, hypothalamic and limbic brain regions. Semiquantitative analysis of aromatase mRNA did not reveal sex differences in any of these regions. In contrast, clear-cut sex differences were determined at postnatal day (PN) 2; male animals expressed significantly more aromatase mRNA in the bed nucleus of stria terminalis (BST) and the sexually dimorphic nucleus of the preoptic area (SDN). Smaller but still significant differences (females > males) were obtained in the medial preoptic area (MPO). At PN6, sex differences of aromatase mRNA signals (males > females) were still present in the BST, but were no longer detectable in the SDN and the MPO. At PN15 and in adult animals, aromatase mRNA levels were similar in BST and medical amygdaloid nucleus of male and female rats. Since aromatase mRNA expression decreases during postnatal development, no ISH signals could be detected anymore in MPO, SDN and ventromedial hypothalamic nucleus. Our results are consistent with the concept that differential regulation of aromatase mRNA expression might be important for the establishment of different neuronal circuitry in male and female animals.     

Manual and computer-aided space analysis: a comparative study

Separate injections of Haemophilus influenzae type b capsular polysaccharide-tetanus conjugate (PRP-T) vaccine and diphtheria-tetanus-pertussis (DTP) reconstitution of freeze-dried PRP-T vaccine with liquid DTP vaccine have been shown to be safe and immunogenic in infants. The present study was conducted to test the safety and immunogenicity of the liquid combination vaccine administered to young infants in the dual-chamber syringe. The study was a monocenter, open clinical trial of 3 month-old infants receiving PRP-T and DTP vaccines in the dual-chamber syringe reconstituted prior to injection. Healthy infants were immunized according to a 3, 4 and 5 months-of-age schedule. The vaccine was administered in a dual-chamber syringe, ready to use with two chambers. The proximal chamber contained freeze-dried PRP-T and the distal chamber contained liquid combination-vaccine DTP. The freeze-dried PRP-T vaccine was reconstituted with the liquid DTP vaccine in the same unidose dual-chamber syringe (0.5 mL) and was injected intramuscularly into the deltoid region. Blood sampling was performed prior to vaccination at 3 months of age and after the third vaccination at 6 months. The primary end-point was the serological response to PRP-T vaccine as expressed by the percentage of infants with an antibody titer greater than or equal to 1 microgram/mL. The reactogenicity was expressed as the percentage of reported local and systemic reactions. A total of 108 infants were included in the study and received the dual-chamber syringe vaccine. After the third injection, all the infants had a PRP antibody titer greater than or equal to 0.15 microgram/mL and 94.4% of infants had a PRP antibody titer greater than or equal to 1 microgram/mL; the pertussis agglutinin titers were over the threshold 40 and 80 in all infants and 98.1% were over the threshold 320. After the third injection, all the infants had diphtheria antibody titers greater than 0.1 IU/mL and 83.3% had titers greater than 1 IU/mL; all the infants had tetanus antibody titers greater than 0.1 IU/mL and 97.2% had results over 1 IU/mL. Thirty-seven infants (34.6%) had local reactions and 64.5% had systemic reactions. The dual-chamber syringe may reduce the cost of vaccine delivery, as well as the workload, and increase the vaccine acceptability and coverage rate of vaccines.     

Radon penetration of concrete slab cracks, joints, pipe penetrations, and sealants

Radon movement through 12 test slabs with different cracks, pipe penetrations, cold joints, masonry blocks, sealants, and tensile stresses characterized the importance of these anomalous structural domains. Diffusive and advective radon transport were measured with steady-state air pressure differences controlled throughout the deltaP = 0 to 60 Pa range. Diffusion coefficients (deltaP = 0) initially averaged 6.5 x 10(-8) m2 s(-1) among nine slabs with only 8% standard deviation, but increased due to drying by 0.16% per day over a 2-y period to an average of 2.0 x 10(-7) m2 s(-1). An asphalt coating reduced diffusion sixfold but an acrylic surface sealant had no effect. Diffusion was 42 times higher in solid masonry blocks than in concrete and was not affected by small cracks. Advective transport (deltaP < or = 60 Pa) was negligible for the slabs (10(-16) m2 permeability), pipe penetrations, and caulked gaps, but was significant for cracks, disturbed pipe penetrations, cold joints, masonry blocks, and concrete under tensile stress. Crack areas calculated to be as small as 10(-7) m2 significantly increased radon advection. Algebraic expressions predict air velocity and effective crack width from enhanced radon transport and air pressures. Masonry blocks, open cracks, and slab cold joints enhance radon penetration but stressed slabs, undisturbed pipe penetrations, and sealed cracks may not.     

National cancer clinical trials: children have equal access; adolescents do not

PURPOSE: To determine whether adolescents with cancer, who in comparison to younger patients have a higher cancer incidence and lower mortality reduction, have equal access to national cancer clinical trials. METHODS: The ethnic/racial distribution of 29,859 subjects < 20 years of age entered onto National Cancer Institute-sponsored clinical trials between January 1, 1991, and June 30, 1994, was compared with the expected distribution of patients of the same age in the United States. RESULTS: The Children's Cancer Group and Pediatric Oncology Group had 29,134 (97.6%) of the total study entries among < 20-year-old subjects during the 3.5 years of surveillance. The adult cooperative groups accounted for < 3% of the clinical trials entries in the 15-19-year age range. When analyzed nationally by region, the under-representation of the older adolescent subjects was universal. From other analyses, the two pediatric cooperative groups were estimated to have registered > 94% of the children < 15 years of age who were expected to have been diagnosed to have cancer, but only 21% of the cancer patients in the 15-19-year age group. CONCLUSIONS: The national pediatric cancer cooperative groups allow the majority of American children < 15 years of age and their families equal opportunity to access clinical cancer trials, regardless of race or ethnicity. Among patients 15-19 years of age, however, > 75% are not being enrolled by any cooperative group sponsored by the National Cancer Institute. Thus, older adolescents are disadvantaged with respect to access to the national clinical trials, regardless of their race or ethnicity.     

Detection of p53 protein overexpression and DNA ploidy analysis in colon cancer

BACKGROUND/AIMS: This study was designed to demonstrate the accumulation of the mutant p53 protein in human neoplasms. The correlation of flow cytometric DNA ploidy pattern with p53 expression using the immunoblotting technique was also investigated. METHODOLOGY: In this study, the occurrence of p53 overexpression was analyzed in 34 cases of adenocarcinoma of the colon by western immunoblotting technique, using an anti-human p53 monoclonal antibody (Do-7). The nuclear protein extract from human colon tumor specimens was immunoblotted relative to protein standards of known molecular weight. Flow cytometric analysis was used to study the DNA ploidy pattern of the tumor cells. RESULTS: Monoclonal antibody p53-Do 7 detected a single band of 53 KDa in 70.5% (24 of 34) of the tumor specimens examined. Whereas, no bands were detected in the normal colon mucosa. The relation between p53 overexpression and the clinicopathological variable (Dukes' staging) was studied and no significant difference in p53 overexpression between Dukes' stages B and C was found. Flow cytometric analysis revealed a higher incidence of DNA aneuploidy in 75% (15 of 20) of p53 positive cases compared with 64.3% (9 of 14) in the diploid tumors. CONCLUSION: The immunoblotting technique can successfully detect the mutant p53 and is therefore expected to provide valuable information on the role of p53 in the process of carcinogenesis.