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Biomedical subjects

Yukiko Yamada

Publications and source records attributed to Yukiko Yamada.

7 recordsLinked to original sources
PubMed2006

Occlusal disharmony induces spatial memory impairment and hippocampal neuron degeneration via stress in SAMP8 mice.

We examined the effect of occlusal disharmony in senescence-accelerated (SAMP8) mice on plasma corticosterone levels, hippocampal neuron number, and spatial performance in the water maze. The bite-raised condition was associated with an accelerated age-related decline in spatial memory, increased plasma corticosterone levels, and a decreased number of neurons in the hippocampal CA3 region. The findings suggest that the bite-raised condition in aged SAMP8 mice induces hippocampal neuron loss, thereby leading to senile memory deficits.

Aging↗
PubMed2005

A catalytic antibody heavy chain HpU-2 degrading its epitope peptide and H. pylori urease.

The HpU-2 monoclonal antibody (mAb) raised against Helicobacter pylori urease mainly recognized the alpha-subunit of the urease. On the other hand, the heavy chain of HpU-2 mAb (HpU-2-H) isolated from the parent mAb recognized both the alpha- and beta-subunit, in which the beta-subunit was recognized more strongly than the beta-subunit. HpU-2-H cleaved a peptide, SVELIDIGGNRRIFGFNALVD, which is the epitope sequence recognized by HpU-2 mAb, showing a double-phase reaction profile at 25 degrees C in a phosphate buffer. After an induction time of 24h, the cleavage of the peptide was initiated by HpU-2-H at a high rate and it was completed at 80 h of incubation. By mass spectroscopy, two main fragmented peptides, SVELIDIGGNRR and SVELIDIGGNRRIFG, were identified. In addition, many small peptide fragments were produced by successive cleavage of the fragmented peptides. Cleavage tests for H. pylori urease by HpU-2-H revealed that the beta-subunit of the urease was cleaved first and completely decomposed at 20 h of incubation. Cleavage of the alpha-subunit started after the complete decomposition of the beta-subunit. These cleavage results were in good agreement with the immunological features of HpU-2-H. The irrelevant proteins, BSA and HSA, were hardly cleaved by HpU-2-H.

Amino Acid Sequence↗
PubMed2005

DNA damage-induced programmed cell death: potential roles in germ cell development.

The detection of DNA damage is necessary to protect against proliferation of potentially harmful cells and often results in cell cycle arrest and programmed cell death. Key components of DNA damage signaling networks include ATM, CHK2, p53, and Bax. Mutations in these damage signaling systems are linked to tumorigenesis and developmental abnormalities. Expression of some of these genes in primordial germ cells (PGCs) argues that PGCs may utilize DNA damage-induced signaling mechanisms to select against germ cells that are genetically defective, thus maintaining the integrity of the germline. This paper summarizes the roles of these DNA damage signaling molecules and addresses their potential involvement in germ cell development.

Animals↗
PubMed2002

Identification of X-linked genes required for migration and programmed cell death of Drosophila melanogaster germ cells.

Drosophila germ cells form at the posterior pole of the embryo and migrate to the somatic gonad. Approximately 50% of the germ cells that form reach their target. The errant cells within the embryo undergo developmentally regulated cell death. Prior studies have identified some autosomal genes that regulate germ cell migration, but the genes that control germ cell death are not known. To identify X-linked genes required for germ cell migration and/or death, we performed a screen for mutations that disrupt these processes. Here we report the identification of scattershot and outsiders, two genes that regulate the programmed death of germ cells. The scattershot gene is defined by a mutation that disrupts both germ cell migration and the death of germ cells ectopic to the gonad. Maternal and zygotic expression of scattershot is required, but the migration and cell death functions can be genetically uncoupled. Zygotic expression of wild-type scattershot rescues germ cell pathfinding, but does not restore the programmed death of errant cells. The outsiders gene is required zygotically. In outsiders mutant embryos, the appropriate number of germ cells is incorporated into the gonad, but germ cells ectopic to the gonad persist.

Animals↗
PubMed2002

Dietary habits and bone stiffness in females aged 18-19 years.

We measured bone stiffness in females aged 18-19 years and observed a mean stiffness of less than 100 (90.2 +/- 10.0). The mean bone stiffness and physique values (height, weight, chest circumference) in these subjects were lower than those in females aged 15-16 years evaluated in our previous study (Yukiko et al., 1997). When the subjects in this study were classified into two groups with a chest circumference > or = and < the mean value (82.2 cm), the former group showed a significantly greater height (p < 0.05), body weight (p < 0.01), and bone stiffness (p < 0.05) than the latter group. When the subjects were classified according to the degree of obesity (BMI), the obese group (BMI > or = 26.0) showed higher bone stiffness (p < 0.05) than the lean group (BMI < or = 20.9). Females in this age range are concerned about their physique and often on a diet, and bone stiffness was higher in those who had dieted than those who had not (p < 0.05). When the subjects were classified according to the age of menarche into two groups with menarche at age < 11 years and > or = 11 years, bone stiffness was higher, chest circumference was about 3 cm greater, and body weight was about 8 Kg higher in the former group than in the latter group. Concerning dietary habits, about 46% of the females aged 18-19 years skipped at least one of the 3 meals. The diet balance (principle food, main dish, side dish, and soup) was poorer (p < 0.01) in the females aged 18-19 years than those aged 13-16 years in our previous study (Yukiko et al., 1997) for breakfast, lunch, and supper. The mean number of consumed food items per day was 15 in the females aged 18-19 years and 21 in those aged 13-16 years, and the mean number of consumed vegetable items was 4.4 in the former and 6.6 in the latter. There was a positive correlation between bone stiffness and the number of consumed food items as well as physique in females aged 12-13 years but not in those aged 18-19 years, suggesting that physical growth has been already completed before the age of 18-19 years. Blood biochemical examinations showed abnormal values in neutral fat, total cholesterol, or serum iron in about 39% of the females aged 18-19 years. Abnormal values were less frequently observed in the group with a mean number of consumed food items > or = 15 than the group with a mean number < 15. The group with abnormal blood biochemical examination values showed significantly higher incidences of "Tend to yawn during the daytime", "Do not defecate every day" and "Have shoulder-low back stiffness" than in the group without abnormal values (p < 0.01).

Adolescent↗