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Biomedical subjects

K Okamura

Publications and source records attributed to K Okamura.

At least 91 records · Page 5Linked to original sources
PubMed2000

Comparative genome analysis of the mouse imprinted gene impact and its nonimprinted human homolog IMPACT: toward the structural basis for species-specific imprinting.

Mouse Impact is a paternally expressed gene encoding an evolutionarily conserved protein of unknown function. Here we identified IMPACT, the human homolog of Impact, on chromosome 18q11. 2-12.1, a region syntenic to the mouse Impact locus. IMPACT was expressed biallelically in brain and in various tissues from two informative fetuses and in peripheral blood from an informative adult. To reveal the structural basis for the difference in allelic expression between the two species, we elucidated complete genome sequences for both mouse Impact ( approximately 38 kb) and human IMPACT ( approximately 30 kb). Sequence comparison revealed that the two genes share a well-conserved exon-intron organization but bear significantly different CpG islands. The mouse island lies in the first intron and contains characteristic tandem repeats. Furthermore, this island serves as a differentially methylated region (DMR) consisting of a hypermethylated maternal allele and an unmethylated paternal allele. Intriguingly, this intronic island is missing from the nonimprinted human IMPACT, whose sole CpG island spans the first exon, lacks any apparent repeats, and escapes methylation on both chromosomes. These results suggest that the intronic DMR plays a role in the imprinting of Impact.

Alleles↗
PubMed2000

Gastrointestinal tract, hepatic, hindlimb, and renal recovery of CO(2) in vivo.

Whole body oxidative rates of labeled substrates are often measured by collecting expired air and determining the amount of labeled CO(2) that is produced. However, the CO(2) produced may not be completely recovered under all circumstances, and there is a wide variation in values reported under different experimental conditions ( approximately 50-100%). The potential contribution of specific organs to this variation has not been defined. In vivo studies using healthy, postabsorptive, multicatheterized conscious canines were conducted to determine gastrointestinal tract, hepatic, hindlimb, and renal recoveries of NaH(14)CO(3) during a 180-min constant infusion [0.022+/-0.002 (SE) microCi x kg(-1) x min(-1)]. Before the constant infusion period, a bolus infusion of NaH(14)CO(3) (1.76+/-0.16 microCi/kg) was given, and the rate of decay in blood was measured over a 15-min period to determine pool size. The pool size for the distribution of (14)CO(2) was approximately 80% of the total body pool (16.0+/-1.7 liters). Whole body recovery was 97.2+/-6.7%. The recoveries across the liver, gut, leg, and kidney were 99.9+/-1.3, 98.0 +/-1.4, 96.7+/-2.6, and 99.9+/-2.1%, respectively. In conclusion, hepatic, gastrointestinal tract, hindlimb, and renal recoveries of CO(2) in vivo were near 100%, suggesting that CO(2) loss is not greater in gluconeogenic organs and that corrections for incomplete recovery of CO(2), when measuring oxidation of substrates across these organs under normal postabsorptive conditions, would be very minor.

Animals↗
PubMed2000

Association of intrauterine growth retardation with monosomy of the terminal segment of the short arm of the X chromosome in patients with Turner's syndrome.

Short stature, which may be a result of intrauterine growth retardation (IUGR), is a characteristic of Turner's syndrome. However, the loci responsible for IUGR have not been well studied. We reviewed the birth records of 74 patients with Turner's syndrome: 20 with pure X monosomy, 44 with X-mosaicisms, and 10 with X-structural abnormalities. The overall incidence of IUGR was 39.2% (29 of 74 patients). The SHOX gene is encoded in a terminal segment of the short arm of the X chromosome. In 39 patients where two copies of the SHOX gene were absent, the incidence of IUGR was 46.2% (18 of 39 patients). In 14 patients with two copies of the SHOX gene, the incidence of IUGR was significantly lower at 7.1% (1 of 14 patients). Our results suggest that SHOX influences in utero growth in Turner's syndrome.

Comorbidity↗
PubMed2000

Foods and nutrients in relation to bladder cancer risk: a case-control study in Aichi Prefecture, Central Japan.

To elucidate the role of diet in the etiology of bladder cancer, we conducted a case-control study from 1996 to 1999 in Aichi Prefecture, Central Japan. Cases were patients newly diagnosed with bladder cancer, and one hospital control was selected for each case, matching gender, age, and hospital. A well-validated food frequency questionnaire was adopted to estimate intakes of nutrients and food groups. Odds ratios (ORs) adjusted for smoking and occupational history were computed using conditional logistic models. The analyses based on 297 cases and 295 controls revealed the following. 1) The more the intake of milk and dairy products, the lower the OR; the ORs across quartiles in all subjects were 1.02, 0.73, and 0.52. Fruit intake was negatively associated with the risk, particularly in men (ORs across quartiles = 0.76, 0.77, and 0.52). Green-yellow vegetables were associated with a decreased risk in the highest quartile of consumption in men (OR = 0.57). 2) Dietary intakes of retinol and saturated fatty acids were related to a reduced risk in all subjects (ORs across quartiles = 0.75, 0.54, and 0.66 and 0.55, 0.54, and 0.60, respectively). Monounsaturated fatty acids had an inverse association with bladder cancer risk in men.

Adult↗
PubMed2000

Two cases of acute myositis associated with influenza A virus infection in the elderly.

During the influenza epidemic of 1998-1999, we observed two elderly patients with influenza-like symptoms who had evidence of acute myositis with elevated serum enzymes. Influenza A infection was confirmed serologically in either case. The present cases suggest that it is important to distinguish influenzal myositis from other forms of myopathy in the elderly patients.

Acute Disease↗
PubMed2000

Telomerase activity in normal ovaries and premature ovarian failure.

The average age for the onset of menopause in humans is about 51 years. On the other hand, premature ovarian failure (POF) is generally defined as the onset of menopause before the age of 40 years. Telomeres have been extensively examined as a mitotic clock. Telomeric DNA is elongated by telomerase. We analyzed the telomerase activity of 20 patients with normal ovaries and 5 patients with POF. Telomerase activity was present in the normal ovaries, however it decreased with age. Eight normal ovaries under 38 years of age showed significantly higher telomerase activity among the women with a regular menstrual cycle. Two POF patients showed high telomerase activity and 3 showed low telomerase activity. Our findings indicate that telomerase is present in the normal human ovary and that telomerase activity decreases with age. Patients with follicle dysfunction showed high telomerase activity and those with follicle depletion showed very low telomerase activity. Based on these results, we speculated that the decline of telomerase activity in the ovary is related to primordial follicle depletion with age and telomerase activity can be used as a marker of the ovarian functional age.

Adult↗
PubMed2000

Compound heterozygous mutations (PHE53/54DEL and HIS373LEU) of the P450c17 gene result in a 17alpha-hydroxylase/17,20-lyase deficient male pseudohermaphrodite with unambiguous external genitalia.

The autosomal recessive disease 17alpha-hydroxylase/17,20-lyase deficiency is characterized by mutation of the P450c17 enzyme, which catalyzes 17alpha-hydroxylation and 17,20-lysis in the steroidogenic pathways. Although 17 mutations of this enzyme have been reported, only a few of them resulted in a completely unambiguous phenotype of female external genitalia in 46, XY individuals. We report here a Japanese patient with a 46,XY karyotype, who showed such a unambiguous female external genitalia. Nucleotide sequencing of the P450c17 gene revealed the patient to be a compound heterozygote carrying two different mutations (PHE53/54DEL in exon 1 and HIS373LEU in exon 6). As these mutations have been previously detected in unrelated Japanese patients, it is confirmed that these mutations accumulate regionally. Since these mutations could be screened by a multiple genotyping method, the method is applicable when 17alpha-hydroxylase/17, 20-lyase deficiency is suspected in Japanese patients.

Adrenal Hyperplasia, Congenital↗
PubMed2000

Growth regulation mechanisms in higher plants under microgravity conditions - changes in cell wall metabolism.

During Space Shuttle STS-95 mission, we cultivated seedlings of rice (Oryza sativa L. cv. Koshihikari and cv. Tan-ginbozu) and Arabidopsis (Arabidopsis thaliana L. cv. Columbia and cv. etr1-1) for 68.5, 91.5, and 136 hr on board, and then analyzed changes in the nature of their cell walls, growth, and morphogenesis under microgravity conditions. In space, elongation growth of both rice coleoptiles and Arabidopsis hypocotyls was stimulated. Also, the increase in the cell wall extensibility, especially that in the irreversible extensibility, was observed for such materials. The analyses of the amounts, the structure, and the physicochemical properties of the cell wall constituents indicated that the decreases in levels and molecular masses of cell wall polysaccharides were induced under microgravity conditions, which appeared to contribute to the increase in the wall extensibility. The activity of certain wall enzymes responsible for the metabolic turnover of the wall polysaccharides was increased in space. By the space flight, we also confirmed the occurrence of automorphogenesis of both seedlings under microgravity conditions; rice coleoptiles showed an adaxial bending, whereas Arabidopsis hypocotyls elongated in random directions. Furthermore, it was shown that spontaneous curvatures of rice coleoptiles in space were brought about uneven modifications of cell wall properties between the convex and the concave sides.

Arabidopsis↗
PubMed2000

[Statistics of the operations at the Department of Urology, Tone Chuo Hospital during a six-year period (June 1993-May 1999)].

A clinical statistic survey was made on the operations performed at the Department of Urology, Tone Chuo Hospital between June 1993 and May 1999. The total number of operations was 1296, consisting of 97 (7.5%) operations of the kidney, 67 (5.2%) operations of the ureter, 190 (14.7%) operations of the bladder, 454 (35.0%) operations of the prostate, 63 (4.9%) operations of the urethra, 92 (7.1%) operations of the penis, 149 (11.5%) operations of the scrotum and 184 (14.2%) other operations. With the aging society, the number of operations for those over 60 years old has exceeded 60%.

Adolescent↗
PubMed1999

Solid cystic tumor of the pancreas in elderly men: report of a case.

Solid cystic tumor of the pancreas is a primary pancreatic neoplasm of unknown etiology that most commonly occurs in young women and ordinarily contains hemorrhagic tissue. We report herein the unusual case of a 75-year-old man found to have a solid cystic tumor in the body and tail of the pancreas, who is the oldest such male patient to be documented in Japan. The results of laboratory data and imaging studies indicated that the patient had a nonfunctioning islet tumor or solid cystic tumor of the pancreas, and distal pancreatectomy with splenectomy was performed. The diagnosis of solid cystic tumor was confirmed based on macroscopic and histological findings of the resected pancreatic tumor. The patient is currently in good health, without any signs of tumor recurrence 1 year and 4 months after his operation. A total of 181 cases of solid cystic tumors of the pancreas reported in the Japanese literature, including our case, were reviewed to evaluate the clinical differences between patients aged 50 years or over and those younger than 50 years.

Aged↗
PubMed1999

Cytokine release during hypoxia reoxygenation by Kupffer cells in rats with obstructive jaundice.

The release of cytokine by Kupffer cells during hypoxia/reoxygenation was studied in vitro in male Wistar rats with obstructive jaundice to investigate the kinetics of interleukin-8 (IL-8) release by Kupffer cells during hypoxia/reoxygenation, and to study the influence of endotoxin during the reoxygenation period. The rats were divided into two groups: one that underwent bile duct ligation (group OJ), and one that underwent a sham operation (group C). Kupffer cells were isolated by collagenase digestion and centrifugal elutriation. The cells were first subjected to hypoxia as 95% nitrogen, after which they were given reoxygenation as 95% oxygen. In addition, they were stimulated with lipopolysaccharide (LPS) 0, 1, and 10 ng/ml. In both groups, the levels of IL-8 became increased during the period of hypoxia/reoxygenation, and reoxygenation after hypoxia further intensified IL-8 production. During the period of hypoxia, the IL-8 levels in group OJ were significantly increased compared with those in group C. With the LPS challenge, there was no significant difference in IL-8 levels in either group. In conclusion, obstructive jaundice induces the activation of Kupffer cells, resulting in increased IL-8 production during hypoxia/reoxygenation.

Analysis of Variance↗
PubMed1999

Combined right hepatic and retrohepatic caval resection with reconstruction using a polytetrafluoroethylene graft for primary leiomyosarcoma of the liver: report of case.

We present herein the case of a 53-year-old woman who underwent successful surgical treatment for a leiomyosarcoma of the liver that originated from the posterior hepatic segment and involved the retrohepatic inferior vena cava (IVC). A computed tomographic scan and magnetic resonance imaging demonstrated a large tumor, with rich vascularity, in the liver. The IVC was found to be occluded on these scans, which was confirmed by venacavography. The patient underwent a combined right hepatic and caval resection with reconstruction using an expanded polytetrafluoroethylene graft. The tumor consisted of spindle-shaped cells with cigar-shaped nuclei. It also had a moderate degree of cellularity and ten mitotic figures per ten high-power fields. Immunohistologically, desmin and alpha-smooth muscle actin were stained positive in the tumor cells, implying that the tumor was derived from smooth muscle cells. The patient is alive and well 15 months after her operation.

Blood Vessel Prosthesis Implantation↗
PubMed1999

Successful surgical treatment for implanted intraperitoneal metastases of ruptured small hepatocellular carcinoma: report of a case.

We report herein the case of a 53-year-old man with disseminated intraperitoneal metastases caused by the rupture of small hepatocellular carcinoma (HCC). He was admitted to our hospital in shock after suffering a trauma injury to the upper abdomen. Ultrasonography revealed a massive hemoperitoneum. At surgery, 4000 ml of blood was drained from the abdominal cavity and a ruptured tumor, 2 cm in diameter, was found in the right lobe of the liver. The tumor was resected with an adequate surgical margin and subsequent microscopic examination confirmed a diagnosis of moderately differentiated HCC without associated liver cirrhosis. The patient was readmitted 14 months later following the development of right lower quadrant pain. Ultrasonography and computed tomography revealed extrahepatic abdominal tumors, and abdominal angiography demonstrated four intraperitoneal tumors. At surgery, four implanted metastases adhered to the greater omentum were found and resected. No other tumors were detected. Microscopically, all four tumors were confirmed as moderately differentiated hepatocellular carcinoma. Ruptured HCC may lead to implanted intraperitoneal metastasis, but rupture of small HCC is very rare. While hepatic resection is the treatment of choice for ruptured HCC, according to our review of the literature, only a few patients have survived long-term after resection of implanted metastasis.

Adult↗
PubMed1999

Increased sensitivity to thyroid hormone replacement therapy followed by hyponatremia and eosinophilia in a patient with long-standing young-onset primary hypothyroidism.

We describe a 51-year-old woman with long-standing young-onset primary hypothyroidism. Serum cortisol, adrenocorticotropin, and arginine vasopressin levels were normal, but urinary excretion of 17-hydroxycorticosteroid was decreased. Administration of a very small initial dose of thyroid hormone induced severe acute complications including fever, palpitation, and sweating associated with a rapid decrease in serum thyrotropin level, a dramatic increase in serum alkaline-phosphatase level, and a decrease in serum total cholesterol level. A week later, the late complications of nausea, severe hyponatremia, and eosinophilia occurred. Serum cortisol level decreased slightly but remained within normal limits during this hyponatremic period. This rare case suggests that increased sensitivity to thyroid hormone can occur in long-standing primary hypothyroidism with biphasic clinical course of acute thyrotoxic complications followed by severe hyponatremia resembling hypoadrenocorticism.

17-Hydroxycorticosteroids↗
PubMed1999

Bone mineral density of the shoulder joint in frozen shoulder.

The purpose of this study was to evaluate the osteopenia in several parts of the shoulder joint in a series of individuals suffering from frozen shoulder and to elucidate the pathogenesis. The bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA). In 30 cases of frozen shoulder, 16 men and 14 women, BMD of the head of the humerus, greater tubercle of the humerus, surgical neck of the humerus, and neck of the scapula was evaluated. The average age of the male patients was 58.4 years and of the women, 59.5 years. At the neck of the scapula, there were no significant differences in any of the cases. However, there was a marked decrease in BMD at the proximal end of the humerus on the affected side of women. In contrast, men showed no significant difference between the affected and unaffected shoulders, suggesting that the degree of osteopenia remains low compared with women. Although frozen shoulder is a disease which may occur in both men and women, the loss of bone was conspicuous only in women. This may be due to the involvement of female hormones in alterations of bone in frozen shoulder, as in cases of osteoporosis, in addition to the originally low bone density in women. The degree of osteopenia of the proximal humerus with frozen shoulder was not correlated with the duration of the disease, range of motion of the shoulder joint, or patient's age.

Absorptiometry, Photon↗
PubMed1999

Effect of amino acids and glucose on exercise-induced gut and skeletal muscle proteolysis in dogs.

The effect of amino acid and/or glucose administration before and during exercise on protein metabolism in visceral tissues and skeletal muscle was examined in mongrel dogs. The dogs were subjected to treadmill running (150 minutes at 10 km/h and 12% incline) and intravenously infused with a solution containing amino acids and glucose (AAG), amino acids (AA), glucose (G) or saline (S) in randomized order. The infusion was started 60 minutes before exercise and continued until the end of the exercise period. An arteriovenous-difference technique was used to estimate both tissue protein degradation and synthesis. When S was infused, the release of leucine (Leu) from the gut and phenylalanine (Phe) from the hindlimb significantly increased during exercise, thus indicating that exercise augmented proteolysis in these tissues. The balance of Leu across the gut during exercise demonstrated a net uptake with both AAG and AA, whereas a net release was observed for G and S. In addition, Leu uptake in the gut during the last 90 minutes of the exercise period tended to be greater with AAG versus AA (P = .06). Phe balance across the hindlimb during the late exercise period showed a significant release with S, AA, and G, whereas the balance with AAG did not show a significant release. These results suggest that exercise-induced proteolysis in the gut may be reduced by supplementation with AA, and this effect may be enhanced by concomitant G administration. However, in skeletal muscle, both AA and G may be required to prevent net protein degradation during exercise. G provided without AA did not achieve net protein synthesis in either tissue.

Amino Acids↗