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T Okada

Publications and source records attributed to T Okada.

At least 127 records · Page 7Linked to original sources
PubMed2001

Pulsed Doppler sonography for the diagnosis of strangulation in small bowel obstruction.

BACKGROUND/PURPOSE: This study was undertaken to assess the usefulness of pulsed Doppler sonography (PDS) for the detection of strangulation in small bowel obstruction by evaluating the hemodynamics in the superior mesenteric artery (SMA). METHODS: The authors performed PDS in 117 normal children: 22 children aged 0 to 1 months (group I), 27 children aged 1 to 12 months (group II), 36 children aged 1 to 6 years (group III), and 32 children aged 7 to 15 years (group IV). Patients included 25 with simple obstruction: 1 in group II, 10 in group III, and 14 in group IV; and 9 with strangulating obstruction: 2 in group I, 2 in group II, 3 in group III, and 2 in group IV. The authors measured the peak-systolic velocity, end-diastolic velocity (EDV), and mean average velocity and calculated the resistive index (RI). RESULTS: The authors observed both a significant decrease in the EDV and increase in the RI for the SMA in strangulating obstruction compared with simple obstruction. CONCLUSION: Analysis of the hemodynamics in the SMA using PDS is useful to differentiate strangulating obstruction from simple obstruction.

Adolescent↗
PubMed2001

Pulsed Doppler sonography of the hilar renal artery: differentiation of obstructive from nonobstructive hydronephrosis in children.

BACKGROUND/PURPOSE: It is difficult to detect the arcuate or cortical renal arteries when performing pulsed Doppler sonography (PDS) for congenital hydronephrosis. This study was undergone to assess the usefulness of PDS of the hilar renal artery to differentiate obstructive from nonobstructive hydronephrosis. METHODS: The authors performed PDS of the hilar renal artery in 80 normal children: 20 aged 0 to 1 months (group I), 20 aged 1 to 12 months (group II), 20 aged 1 to 6 years (group III), and 20 aged 7 to 15 years (group IV). Based on diuretic renography findings, 22 kidneys from 19 children with a ureteropelvic junction (UPJ) stricture were divided into 7 dilated obstructed and 15 dilated nonobstructed kidneys. The peak-systolic velocity (PSV), end-diastolic velocity (EDV), mean average velocity (Vm) and the resistive index (RI = [PSV - EDV]/PSV) were measured at the hilar renal artery. RESULTS: There was a significant difference in the RI of the hilar renal artery between obstructive and nonobstructive hydronephrosis. CONCLUSION: A pulsed Doppler evaluation of the hilar renal artery is useful for detecting an obstructive UPJ stricture compared with assessing arcuate or cortical renal arteries.

Adolescent↗
PubMed2001

Successful surgical treatment of two cases of congenital chylous ascites.

The authors report on 2 patients with congenital chylous ascites who underwent successful lymphatic duct ligation after a laparoscopic lymphoid dye test. Fetal ascites had been detected in both cases, and both babies were born with marked abdominal swelling. Given that conservative treatment by medium-chain triglyceride (MCT) milk and total parenteral nutrition (TPN) was ineffective, the authors elected to perform lymphatic duct ligation on the 95th postnatal day in the former case and on the 27th postnatal day in the latter case. Lipophilic dye was administered preoperatively both through oral and subcutaneous routes, and the peritoneal cavity was explored using laparoscopy. This laparoscopic lymphoid dye test precisely identified the area of chylous leakage, and the authors were able to repair the malformed lymphatic duct directly at laparotomy. Both postoperative courses have been favorable with no recurrence of symptoms. The lymphatic duct ligation should be considered in cases resistant to conservative treatment for over a month. The present laparoscopic lymphoid dye test is a novel and useful procedure that allows surgeons to identify the exact location of chylous leakage, and thus successfully ligate the lymphatic duct.

Chylous Ascites↗
PubMed2001

Dissociable mechanisms of attentional control within the human prefrontal cortex.

Neuropsychological tests that require shifting an attentional set, such as the Wisconsin Card Sorting Test, are sensitive to frontal lobe damage. Although little information is available for humans, an animal experiment suggested that different regions of the prefrontal cortex may contribute to set shifting behavior at different levels of processing. Behavioral studies also suggest that set shifting trials are more time consuming than non-set shifting trials (i.e. switch cost) and that this may be underpinned by differences at the neural level. We determined whether there were differential neural responses associated with two different levels of shifting behavior, that of reversal of stimulus-response associations within a perceptual dimension or that of shifting an attentional set between different perceptual dimensions. Neural activity in the antero-dorsal prefrontal cortex increased only in attentional set shifting, in which switch costs were significant. Activity in the postero-ventral prefrontal cortex increased not only in set shifting but also in reversing stimulus-response associations, in which switch costs were absent. We conclude that these distinct regions in the human prefrontal cortex provide different levels of attention control in response selection. Thus, the antero-dorsal prefrontal cortex may be critical for higher order control of attention, i.e. attentional set shifting, whereas the postero-ventral area may be related to a lower level of shift, i.e. reorganizing stimulus-response associations.

Adult↗
PubMed2001

Reverse transcriptional mutagenesis induced by ribonucleoside triphosphate analogue, PTP and its availability for anti-HIV-1 therapy.

The bicyclic pyrimidine analogue, 3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-7-one (P) can base pair with both A and G. The riboside 5'-triphsophate of P (PTP) efficiently induces mutation during in vitro transcription and reverse transcription cycles using a phage promoter. In the present study, we have constructed an in vitro transcription system promoted by the human immunodeficiency virus type 1 (HIV-1) 5'-long terminal repeat (LTR) using HeLa nuclear extract supplemented with HIV-1 Tat protein. Using this system, the effects of mutagenic ribonucleotide analogues were studied.

Anti-HIV Agents↗
PubMed2001

Iron accumulation in the liver of male patients with Wilson's disease.

OBJECTIVES: There is accumulating evidence that ceruloplasmin, a copper protein with ferroxidase activity, plays an important role in iron metabolism. The genetic disorder, aceruloplasminemia, can lead to tissue storage of iron as in hemochromatosis. Because most patients with Wilson's disease, a genetic copper toxicosis, have hypoceruloplasminemia, some could be affected by iron overload. METHODS: Four male patients with Wilson's disease were enrolled in this study of pre- and post-treatment iron metabolism. RESULTS: Pretreatment copper contents of the liver were high in all four male patients studied as diagnostic of Wilson's disease. Genetic analysis supported their clinical diagnosis of Wilson's disease without a background of hemochromatosis. Pretreatment serum ceruloplasmin levels were <20 mg/dl in all four patients. A standard penicillamine treatment for 3-8.5 yr further decreased their serum ceruloplasmin levels. Post-treatment serum ferroxidase activity was low as was the serum ceruloplasmin protein. Copper contents in the liver decreased after treatment in all subjects. In contrast, nonheme iron in the liver increased during treatment. Pretreatment liver specimens were positive for histochemical iron in two patients, and post-treatment specimens were positive in all four patients. In two patients, serum aminotransferase levels rebounded with elevation of serum ferritin concentration during the treatment period. Subsequent iron reduction by phlebotomy ameliorated their biochemical liver damage. CONCLUSION: Iron overload related to hypoceruloplasminemia may be clinically important, particularly in male patients with Wilson's disease.

Adolescent↗
PubMed2001

Endoplasmic reticulum stress-induced formation of transcription factor complex ERSF including NF-Y (CBF) and activating transcription factors 6alpha and 6beta that activates the mammalian unfolded protein response.

The levels of molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) are controlled by a transcriptional induction process termed the unfolded protein response (UPR). The mammalian UPR is mediated by the cis-acting ER stress response element (ERSE), the consensus sequence of which is CCAAT-N(9)-CCACG. We recently proposed that ER stress response factor (ERSF) binding to ERSE is a heterologous protein complex consisting of the constitutive component NF-Y (CBF) binding to CCAAT and an inducible component binding to CCACG and identified the basic leucine zipper-type transcription factors ATF6alpha and ATF6beta as inducible components of ERSF. ATF6alpha and ATF6beta produced by ER stress-induced proteolysis bind to CCACG only when CCAAT is bound to NF-Y, a heterotrimer consisting of NF-YA, NF-YB, and NF-YC. Interestingly, the NF-Y and ATF6 binding sites must be separated by a spacer of 9 bp. We describe here the basis for this strict requirement by demonstrating that both ATF6alpha and ATF6beta physically interact with NF-Y trimer via direct binding to the NF-YC subunit. ATF6alpha and ATF6beta bind to the ERSE as a homo- or heterodimer. Furthermore, we showed that ERSF including NF-Y and ATF6alpha and/or beta and capable of binding to ERSE is indeed formed when the cellular UPR is activated. We concluded that ATF6 homo- or heterodimers recognize and bind directly to both the DNA and adjacent protein NF-Y and that this complex formation process is essential for transcriptional induction of ER chaperones.

Activating Transcription Factor 6↗
PubMed2001

Perinatal development of the rat kidney: proliferative activity and epidermal growth factor.

The immunolocalization of proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF) and its receptor (EGFR) was examined in the perinatal rat kidney. As the index of proliferative activity, PCNA-positive cell ratios in glomeruli and proximal tubules were determined. The PCNA-positive ratios in both glomeruli and proximal tubules decreased significantly during the perinatal period and tended to decrease as the glomerular developmental stage proceeded as well. PCNA-positive cells were seen predominantly in the nephrogenic zone of the kidney throughout the period examined. They were noted in the collecting ducts of the nephrogenic zone and were rarely seen in those of the central zone of the kidney. On the other hand, PCNA-positive cells were noted in the straight portion of the proximal tubules and were rarely seen in the convoluted one. EGF-positive cells were seen in the proximal tubules, distal tubules and collecting ducts, though EGF-positive cells in the proximal tubules decreased after birth. EGFR-positive cells were seen along the entire length of the proximal tubules and collecting ducts as well as in immature glomeruli, not in mature ones. These results indicate that marked cell proliferation occurs in the collecting ducts in the peripheral area and in the proximal tubules in the central area of the kidney, that the proliferative activity decreases with age during the perinatal days and that EGF plays an important role in the proliferation of glomerular cells, and in both proliferation and maturation of the cells in the proximal tubules and collecting ducts.

Animals↗
PubMed2001

Cloning and characterization of gonadotropin-inducible ovarian transcription factors (GIOT1 and -2) that are novel members of the (Cys)(2)-(His)(2)-type zinc finger protein family.

Gonadotropins are essential for ovarian follicular development and differentiation. To identify genes that are rapidly induced by gonadotropin in the immature rat ovary, ovarian genes were screened by a subtraction cloning procedure. cDNA clones encoding novel members of the (Cys)(2)-(His)(2)-type zinc finger protein family GIOT1 and -2 (gonadotropin-inducible transcription factor 1 and 2), were identified. Two isoforms of GIOT2 (GIOT2 alpha and 2 beta), which are probably produced by alternative splicing, also exist. Nucleotide sequence analysis revealed that GIOT1, but not GIOT2, contains the krüppel-associated box-A domain at the NH(2) terminus. RNA analyses revealed that these mRNAs were rapidly and temporarily induced by gonadotropins in the rat testis as well as in the ovary. In situ hybridization study revealed that expression of GIOT1 was induced in theca interna cells in the ovary and Leydig cells in the testis. Interestingly, the gene expression of GIOT1 is restricted to the pituitary, adrenal, testis, and ovary, while GIOT2 gene is expressed ubiquitously. A functional analysis of GIOT1 and -2 by a GAL4-based mammalian one-hybrid system revealed that GIOT1, but not GIOT2, is a transcriptional repressor and that the krüppel-associated box-A domain of GIOT1 is responsible for the transcriptional repressor activity. A GAL4-based yeast two-hybrid system was also used to identify proteins that interact with the rat GIOT1. We cloned genes encoding rat homologs of human I-mfa domain containing protein and transcriptional intermediary factor 1 beta, both of which are transcription-regulatory proteins. Interaction of these proteins with GIOT1 was directly demonstrated by GST pull-down assay. Our data strongly suggest that GIOT1 may function as a novel transcriptional repressor by working with rat homologs of human I-mfa domain containing protein and transcriptional intermediary factor 1 beta proteins and may play a significant role at the transcription level in the folliculogenesis.

3T3 Cells↗
PubMed2001

New mu-opioid receptor agonists with piperazine moiety.

New mu-opioid receptor (MOR) agonists containing piperazine and homopiperazine moieties in the structures were synthesized and their affinities to and agonist potencies on MOR were evaluated. Among the synthesized compounds, 4-[4-(2-methoxyphenyl)piperazin-1-yl]-N,N-dimethyl-2,2-diphenylbutanamide (20 Aa) showed the highest affinity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells, and the highest agonist potency on the MOR in isolated guinea-pig ileum preparation.

Animals↗
PubMed2001

Noninvasive assessment of the early progression of atherosclerosis in adolescents with Kawasaki disease and coronary artery lesions.

OBJECTIVES: The severity of carotid arteriosclerosis, defined as increased intima-media thickness (IMT) visible with B-mode ultrasound, is correlated with risk factors for coronary heart disease. Little is known, however, about the relation of IMT, the stiffness of the common carotid artery, and the progression of atherosclerosis in children with Kawasaki disease (KD) and coronary artery lesions (CAL). DESIGN: We investigated the associations among total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride, TC/HDL-C, ApoE genotype, glycohemoglobin, IMT, and arterial stiffness by high resolution ultrasound in 20 adolescents with KD and CAL (age: 16.6 +/- 4.1 years, males: 60%) and 20 sex- and age-matched healthy controls (Cont). RESULTS: No significant differences were observed in the values of body mass index and blood pressure between the 2 groups. Also no significant differences were observed in the levels of TC, LDL-C, HDL-C, triglyceride, TC/HDL-C within normal values, or the allele frequency of Apo E4 between the 2 groups. However, the values of IMT, stiffness, and glycohemoglobin in patients with KD were significantly higher than those in Cont (0.53 +/- 0.07 vs 0.46 +/- 0.05 mm, P <.05; 4.11 +/- 0.86 vs 2.94 +/- 0.91, P <.001; 5.0 +/- 0.4 vs 4.6 +/- 0.2%, P <.05). A significant relationship was observed between sex and the mean IMT (r = 0.46) in Cont; however, no significant correlation was found between mean IMT and other variables in either group. Although the arterial stiffness was strongly related to body mass index (r = 0.58) and systolic blood pressure (r = 0.55) in Cont, no significant relationship was observed between the stiffness and any variable tested in patients with KD. CONCLUSIONS: The less distensible carotid wall in patients with KD compared with that in Cont without major alteration of the lipid profile is likely to be secondary to the changes in arterial walls after a diffuse vasculitis involving noncoronary arteries. These results indicate that the coronary arteries may be predisposed to accelerated atherosclerosis in patients with KD and CAL.

Adolescent↗
PubMed2001

A loss of aggressive behaviour and its reinstatement by oestrogen in mice lacking the aromatase gene (Cyp19).

Aromatase P450 (CYP19) is an enzyme responsible for conversion of androgens to oestrogens. We generated CYP19 knockout (ArKO) mice by targeting disruption of the CYP19 gene and observed that the ArKO males exhibited a complete loss of aggressive behaviour against intruder mice when examined using a resident-intruder paradigm. The defect in the behaviour of ArKO males was reinstated when the mice received supplements of 17beta-oestradiol soon after birth. Nevertheless, the cumulative duration of the behaviour displayed by the treated mice during the test period of 15 min was 19+/-10 s, which was much shorter than that displayed by wild-type males, 90+/-17 s. When the supplementation was started at 7 days after birth, the defect was not restored. These findings illustrate an absolute requirement for oestrogen during the neonatal stage of a male's life for the development of the potential for aggression observed in adulthood. Furthermore, the present study demonstrates that ArKO males are a useful model in which to investigate the neural mechanisms by which aggressive behaviour is controlled.

Age Factors↗
PubMed2001

Oestrogen at the neonatal stage is critical for the reproductive ability of male mice as revealed by supplementation with 17beta-oestradiol to aromatase gene (Cyp19) knockout mice.

Aromatase P450 (CYP19) is an enzyme responsible for the conversion of androgens to oestrogens. We generated CYP19 knockout (ArKO) mice by targeted disruption of Cyp19 and studied the role of oestrogens in male reproductive ability. Approximately 85% of ArKO males were unable to sire offspring. However, no obvious difference was found in testicular and epididymal weights, numbers of sperm in the epididymis or the ability of sperm to fertilize eggs in vitro between wild-type and ArKO males. An examination of mating behaviour demonstrated that ArKO males showed an impairment in mounting behaviour against sexually mature females. The inability of more than 90% of ArKO males to sire offspring was reversed by repeated subcutaneous injections of 17beta-oestradiol when initiated on the day of birth. The effects of 17beta-oestradiol on reproduction were concentration dependent and evident when supplementation was initiated on day 7, but not on day 15 after birth. These findings suggest that oestrogens acting during neonatal life are required for normal mating behaviour in adulthood.

Age Factors↗
PubMed2001

Targeted disruption of the aromatase P450 gene (Cyp19) in mice and their ovarian and uterine responses to 17beta-oestradiol.

Aromatase P450 (CYP19) is an enzyme catalysing the conversion of androgens into oestrogens. We generated mice lacking aromatase activity (ArKO) by targeted disruption of Cyp19 and report the characteristic features of the ArKO ovaries and uteri as revealed by histological and biochemical analyses. ArKO females were totally infertile but there were as many developing follicles in their ovaries at 8 weeks of age as in wild-type ovaries. Nevertheless, no typical corpus luteum was observed in the ArKO ovaries. Electron microscopy revealed the presence of well-developed smooth endoplasmic reticulum, few lipid droplets and mitochondria with less organized tubular structures in the ArKO luteinized interstitial cells. These ultrastructural features were different from those of the wild-type interstitial cells, where there are many lipid droplets and mitochondria with well-developed tubular structures, characteristic of steroid-producing cells. When ArKO mice were supplemented with 17beta-oestradiol (E(2); 15 microg/mouse) every fourth day from 4 weeks of age for 1 month, increased numbers of follicles were observed in the ovaries as compared with those of untreated ArKO mice, although no typical corpus luteum was detectable. Ultrastructural analysis revealed the disappearance of the accumulated smooth endoplasmic reticulum in the luteinized interstitial cells after E(2 )supplementation. Transcripts of pro-apoptotic genes such as p53 and Bax genes were markedly elevated in the ArKO ovaries as compared with those of wild-type mice. Although E(2) supplementation did not cause suppression of the elevated expression of p53 and Bax mRNAs, it caused marked enhancement of expression levels of lactoferrin and progesterone receptor mRNAs in the uteri as well as increases in uterine wet weight. At 8 months of age, ArKO mice developed haemorrhages in the ovaries, in which follicles were nearly depleted, while age-matched wild-type females still had many ovarian follicles. Furthermore, macrophage-like cells were occasionally observed in the ArKO ovarian follicles. These results suggested that targeted disruption of Cyp19 caused anovulation and precocious depletion of ovarian follicles. Additionally, analysis of mice supplemented with E(2) demonstrated that E(2) apparently supports development of ovarian follicles, although it did not restore the defect in ovulation.

Animals↗
PubMed2001

EST analysis of genes that are expressed in the neural complex of Ciona intestinalis adults.

A subtractive cDNA library was made corresponding to mRNAs expressed in the neural complex relative to those expressed in the pharynx of adults of the ascidian Ciona intestinalis. Determination and comparison of expressed sequence tags (ESTs) of a set of 1,527 randomly selected clones demonstrated that they represent 832 independent sequences. Five hundred seventy-two of the clones contained amino-acid-encoding sequences. BLASTX analyses showed that 342 of the 572 clones were strong matches (P < 10(-7)) to previously identified proteins, while the remaining 230 fell into the "no match" category. Among the clones matching previously identified proteins, about 80 clones represented proteins that are involved in the formation, maintenance of the structure, and function of the nervous system: 22 proteins are associated with signal transduction, five proteins are related to the synapse, 11 to transcription factors, nine to transporters, five to enzymes, and 13 to extracellular matrix and cytoskeletal components, and six to apoptosis. In addition, sequence information for genes associated with the immune system and for genes encoding proteins with interesting functions were obtained. These data provide cues for further studies on genes that are expressed in and function in the ascidian nervous system.

Animals↗
PubMed2001

Neuronal form in the central nervous system of the tadpole larva of the ascidian Ciona intestinalis.

The dorsal tubular central nervous system (CNS) of the ascidian tadpole larva is a diagnostic feature by which the chordate affinities of this group, as a whole, are recognized. We have used two methods to identify larval neurons of Ciona intestinalis. The first is serial electron microscopy (EM), as part of a dedicated study of the visceral ganglion (1), and the second is the transient transfection of neural plate progeny with green fluorescent protein (GFP) (2), to visualize the soma and its neurites of individual neurons in whole-mounted larvae of C. intestinalis. Our observations reveal that ascidian larval neurons are simple inform, with a single axonal neurite arising from a soma that is either monopolar or has only very few, relatively simple neurites arising from it, as part of a presumed dendritic arbor. Somata in the visceral ganglion giving rise to axons descending in the caudal nerve cord are presumed to be those of motor neurons.

Animals↗