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Biomedical subjects

Y Kojima

Publications and source records attributed to Y Kojima.

At least 145 records · Page 8Linked to original sources
PubMed1998

Phenotypic discordance in monozygotic twins with 22q11.2 deletion.

We report on male monozygotic twins with 22q11.2 deletion and discordant phenotypes. The twins had twin-to-twin transfusion syndrome. Twin 1, the smaller of the pair, had Tetralogy of Fallot, a characteristic facial appearance, swallowing dysfunction, anal atresia, short stature, and mental retardation, whereas twin 2 had a characteristic facial appearance but no other signs of the 22q11 deletion syndrome. Fluorescence in situ hybridization analysis showed a microdeletion on chromosome 22q11.2 in both twins. Zygosity analysis gave a probability of monozygosity greater than 99.999%. These observations indicate that environmental factors or postzygotic events play a role in the phenotypic variability in the twins.

Abnormalities, Multiple↗
PubMed1998

Binding site for blood coagulation factor Xa involving residues 311-325 in factor Va.

Factor Va inactivation by activated protein C is associated with cleavages at Arg306, Arg506, and Arg679 with Arg306 cleavage causing the major activity loss. To study functional roles of the Arg306 region, overlapping 15-mer peptides representing the sequence of factor Va residues 271-345 were synthesized and screened for anticoagulant activities. The peptide containing residues 311-325 (VP311) noncompetitively inhibited prothrombin activation by factor Xa, but only in the presence of factor Va. Fluorescence studies showed that VP311 bound to fluorescence-labeled 5-dimethylaminonaphthalene-1-sulfonyl-Glu-Gly-Arg factor Xa in solution with a Kd of 70 microM. Diisopropylphosphoryl factor Xa and factor Xa but not factor VII/VIIa or prothrombin bound to immobilized VP311 with relatively high affinity. These results support the hypothesis that residues 311-325, which are positioned between the A1 and A2 domains of factor Va and likely exposed to solvent, contribute to the binding of factor Xa by factor Va. Based on this hypothesis, it is suggested that cleavage by activated protein C at Arg306 in factor Va not only severs the covalent connection between the A1 and A2 domains but also disrupts the environment and structure of residues 311-325, thereby down-regulating the binding of factor Xa to factor Va.

Amino Acid Sequence↗
PubMed1998

A de novo missense mutation (R1623Q) of the SCN5A gene in a Japanese girl with sporadic long QT sydrome. Mutations in brief no. 140. Online.

Two missense mutations and a nine-nucleotide deletion of the cardiac sodium channel (SCN5A) gene have been shown to cause long QT syndrome (LQTS) in several familial cases. We identified a novel missense mutation (R1623Q) of the SCN5A gene in a Japanese girl with sporadic LQTS. We used polymerase chain reaction, single-strand conformation polymorphism analysis and DNA sequence analysis to identify a mutation of the SCN5A gene in the patient. A single nucleotide substitution of guanine to adenine, in codon 1612, changed the coding sense of the SCN5A from arginine to glutamine (R1623Q) in the S4 segment of domain IV which is a highly conserved region of the SCN5A. This mutation was not identified in the unaffected biological parents and brother of the patient, and 100 normal, unrelated individuals. This finding is the first evidence of a de nova mutation in SCN5A associated with LQTS.

Amino Acid Substitution↗
PubMed1998

Electrophysiological studies of early stage corticobasal degeneration.

We conducted electrophysiological studies in two Asian patients with probable corticobasal degeneration (CBD). The duration of illness from onset was 16 and 20 months, respectively. The clinical manifestations were markedly asymmetric and characterized by cortical sensory loss, apraxia, action myoclonus, action tremor, and akinetic-rigid parkinsonism. Neither patient responded to levodopa therapy. Simple photon-emission computed tomography (SPECT) study showed significantly decreased regional cerebral blood flow in the frontoparietal areas and thalamus opposite to the predominantly affected limb. A series of electrophysiological studies failed to identify giant somatosensory evoked potentials (SEPs), enhanced long latency electromyography (EMG) reflex, and cortical spikes preceding myoclonic jerk. However, the earliest cortical component of the median nerve SEP was exclusively enlarged in one patient and preserved with depression of the subsequent components in the other patient. Significantly shorter postmotor-evoked potential (MEP) silent period was found after the transcranial magnetic stimulation of the motor cortex in both patients. CBD is a unique clinical entity characterized by action myoclonus probably the result of the pathologic hyperexcitability of the motor cortex, based on a loss of inhibitory input from the sensory cortex.

Aged↗
PubMed1998

Pathophysiological appraisal of a rat model of total hepatic ischemia with an extracorporeal portosystemic shunt.

BACKGROUND: Animal models of total hepatic ischemia (THI) and reperfusion injury are restricted by concomitant splanchnic congestion. This study was performed to determine the requirement suitable for an extracorporeal portosystemic shunt (PSS) to maintain the intestinal integrity in a rat model of THI. MATERIALS AND METHODS: Using a polyethylene tube (0.86 or 1 mm i.d.), PSS was placed between the mesenteric and jugular veins. Comparison was done between THI models with or without PSS and a partial ischemia model with hepatectomy of the nonischemic lobes. Well-tolerated hepatic ischemic period, portal pressure after 10 min of hepatic ischemia, portal endotoxin levels at 1 h after reperfusion, histological features of the small bowel just before reperfusion, and local jejunal and ileal blood hemoglobin oxygen saturation index (ISO2) were compared among the models. RESULTS: Animals without PSS poorly tolerated 30 min of THI. Animals receiving THI with PSS or partial hepatic ischemia tolerated a longer ischemic period (60 min) with a significantly higher small bowel ISO2, lower portal pressure and endotoxin levels (P < 0.01), and less histological damage of the small bowel when compared to those receiving THI without PSS. Portal endotoxin levels after THI with PSS using a 1-mm i.d. tube as well as partial hepatic ischemia were significantly lower than those after THI with PSS using a 0.86-mm i.d. tube. CONCLUSIONS: THI with PSS using a 1-mm i.d. tube was strikingly similar to partial hepatic ischemia in the pathophysiological profile during hepatic ischemia. PSS with a tube 1 mm or more in inner diameter offers pathophysiological advantages in experiments on THI and reperfusion.

Animals↗
PubMed1998

Multiple early bile duct carcinoma associated with congenital choledochal cyst.

Emergency ultrasonography showed a protruding tumor in the markedly dilated common bile duct of a 33-year-old Japanese woman. Magnetic resonance cholangiopancreatography also demonstrated the tumor clearly, almost as clearly as did percutaneous transhepatic cholangiography. With a diagnosis of common bile duct carcinoma associated with congenital choledochal cyst, pancreaticoduodenectomy was performed. In the resected specimen, as well as the protruding tumor, there was also a small slightly elevated lesion. Pathology examination showed adenocarcinoma limited to the fibromuscular layer in the protruding tumor, and adenocarcinoma limited to the mucosa in the elevated lesion. Prophylactic total excision of the choledochal cyst before the occurrence of malignant change is strongly recommended in patients with congenital choledochal cyst. However, in those who are reluctant to undergo the operation, periodic follow-up with ultrasonography and magnetic resonance cholangiopancreatography would be ideal to achieve early detection of malignant change.

Adenocarcinoma↗
PubMed1998

Effects of epidermal growth factor on the invasion activity of the bladder cancer cell line.

PURPOSE: Epidermal growth factor (EGF) is excreted in high concentrations in the urine and stimulates urothelial cell growth. The cultured bladder cancer cell line KU-1 was used to study the molecular mechanisms by which EGF affects urothelial tumor growth and invasion activity. MATERIALS AND METHODS: KU-1 cells were grown in cell culture in the presence or absence of EGF. Anchorage-independent cell growth assays and Matrigel invasion assays were performed. Expression of cytokeratins was examined by Northern and Western blot analyses. Chloramphenicol acetyltransferase assays were used to determine whether EGF stimulated matrix metalloproteinase expression. RESULTS: EGF enhanced anchorage-independent growth in soft agar and increased the number of cells penetrating into a Matrigel membrane. A transient transfection assay revealed that EGF increased the promoter activities of the matrix metalloproteinase 1 and 9 genes in KU-1 cells. Moreover, the morphology of KU-1 cells changed after the addition of EGF to the culture medium. Western and Northern blot analyses demonstrated that EGF decreased cytokeratin 19 expression, but did not affect expression of cytokeratin 8 or 18. CONCLUSION: EGF increased the invasive activity of KU-1 bladder cancer cells in part by increasing the secretion of matrix metalloproteinases. Morphologic changes may result from altered composition of cytoskeletal proteins.

Epidermal Growth Factor↗
PubMed1998

Distinct effects of tetragastrin in rat gastroduodenal mucosa on mucin content and mucosal protective action against histamine-induced injury.

We examined the effects of tetragastrin on mucin (mucus glycoprotein) content and mucosal damage in the rat stomach and duodenum. Following an injection of tetragastrin (12, 120, or 400 microg/kg subcutaneously), no macroscopic damage was found to the gastric mucosa but an increase in corpus mucin content was noted, whereas mucosal lesions appeared and the mucin content decreased in the duodenum in a dose-related manner. In the groups with histamine (0.8, 8, or 80 mg/kg intraperitoneally) administration, the extent of mucosal damage and the decrease in mucin content were dose-related in both these regions. For assessment of the effect of tetragastrin on the protective action in gastroduodenal mucosa, changes in mucin content and mucosal damage with histamine (80 mg/kg) -induced injury were examined. Coadministration of tetragastrin prevented the gastric mucosal damage and inhibited the decrease in corpus mucin content. In the duodenum, tetragastrin aggravated the histamine-induced mucosal damage and did not inhibit the reduction of the mucin content. From the present results, the increase in gastric mucins induced by tetragastrin might be related to the protective effect of gastric mucosa against injury. Tetragastrin did not protect the duodenal mucosa, and histamine-induced injury occurring in this region would be aggravated by the increase in HCl secretion and the decrease in mucin content induced by tetragastrin.

Animals↗
PubMed1998

Mucosal morphological changes in the ileal neobladder.

OBJECTIVE: To determine the ultrastructural changes in the mucosa of intestinal segments used as a neobladder. MATERIALS AND METHODS: Biopsy specimens from the ileal neobladders of eight men (mean age 62 years, range 52-68) who had undergone radical cystectomy were assessed by light and electron microscopy from 1 month to 5 years after operation. The morphology was compared with that in control specimens obtained from three patients of similar age during construction of an ileal neobladder after radical cystectomy. RESULTS: Light microscopy showed shorter mucosal villi and fewer goblet cells. Marked oedema was found in all ileal neobladder walls. Electron microscopy revealed fewer and shorter microvilli and fewer filamentous core rootlets; cell borders were irregular, there were few senile cells in the tip of the villi and more desmosomes. CONCLUSIONS: The absorptive and secretory function of the intestinal mucosa was probably decreased; the oedema of transferred ileal mucosa seemed to be associated with an inflammatory cell reaction. The cellular dynamics of the mucosa of the ileal neobladder changed with time, thus the ileal mucosa in the substitute bladder apparently adapted well to the new environment, i.e. urine retention, and neobladder expansion and contraction.

Aged↗
PubMed1998

Results of closure of urethrocutaneous fistulas after hypospadias repair.

BACKGROUND: Urethrocutaneous fistulas are one of the major causes of morbidity after hypospadias repair. METHODS: During the last 2.5 years, 26 patients underwent repair of 41 urethrocutaneous fistulas. These fistulas were repaired by a 3-layered closure method, by using meticulous surgical techniques aided by optical magnification. In large fistulas, a dermal subcutaneous flap was created and brought over the surgically repaired urethral fistula. RESULTS: Twenty-four of the 26 patients with urethrocutaneous fistulas after hypospadias repair had fistula closure, with a 92% success rate. CONCLUSION: A high success rate was obtained with a multilayered closure using meticulous techniques to repair urethrocutaneous fistulas.

Adolescent↗
PubMed1998

Antitumor effect of irinotecan hydrochloride (CPT-11) on human renal tumors heterotransplanted in nude mice.

BACKGROUND: There has been a paucity of antitumor drugs that are active against renal tumors. Irinotecan hydrochloride (CPT-11), a DNA topoisomerase type 1 inhibitor, has demonstrated antitumor activity against human tumors, however, no antitumor effect of CPT-11 on renal tumors has been reported. The antitumor effect of CPT-11 was investigated on 2 human renal tumors (OUR-10 and OUR-20) heterotransplanted into nude mice. METHODS: Tumor-bearing nude mice were given daily intraperitoneal injections of multiple anticancer drugs suspended in 0.2 mL of phosphate-buffered saline (PBS) 3 times at 3-day intervals. Control mice were injected with 0.2 mL of PBS. The antitumor effects were evaluated by calculating the T/C ratio (treated tumors/controls) of the tumor volume. RESULTS: Among the 10 anticancer drugs tested, 50 mg/kg of CPT-11 showed an active antitumor effect on OUR-20 (T/C ratio 34). However, all drugs tested on OUR-10 failed to show antitumor activity. CONCLUSION: Since CPT-11 was effective in 1 of 2 renal tumors examined without severe toxicity, this drug could be a candidate for chemotherapy of renal cell carcinoma.

Animals↗
PubMed1998

Intrapelvic malignant schwannoma resected transsacrally.

Malignant schwannoma arising in the retroperitoneum is rare. A 68-year-old man underwent transsacral resection for an intrapelvic tumor which proved to be a malignant schwannoma. The transsacral approach is simple and effective, and should be considered for primary management of retrovesicular and retroprostatic tumors.

Aged↗
PubMed1998

Cell biological analysis with respect to cause of fibrous opacification of the anterior capsule after cataract extraction.

It has been assumed that lens epithelial cells (LECs) existing at the capsulotomy edge have been traumatized through anterior capsulotomy in cataract extraction. In this study, the correlation between traumatized LECs remaining at the anterior capsulotomy edge and epidermal growth factor (EGF) found in the aqueous humor, a cell growth factor though to affect cell morphology, was determined. Anterior lens capsules with adhering LECs were obtained following anterior capsulotomy performed during cataract surgery to first confirm the presence of EGF receptors on LECs, which are needed for EGF to be biologically active. Besides, to identify any EGF receptors on traumatized LECs, I next intentionally traumatized the cells by pressing them with a forceps from the anterior capsular side. It has been found that the LECs containing EGF receptors were always those existing at the edge of the anterior capsular opening and LECs containing EGF receptors existed along the pressed region too. The present results indicate that traumatized LECs along the capsulotomy edge have undergone changes to manifest EGF receptors, thus allowing EGF from the aqueous humor to become more active. The physiological effect of EGF upon these LECs may therefore be one of the causative factors of fibrous opacification of the anterior capsulotomy edge after cataract extraction.

Aged↗
PubMed1998

Detection of the sex-determining region of the Y chromosome in 46,XX true hermaphroditism.

OBJECTIVES: Two cases of 46,XX true hermaphroditism were analyzed for two Y-DNA sequences, including the recently cloned gene for male testis determination, the sex-determining region of the Y chromosome (SRY). METHODS: Polymerase chain reaction was performed to amplify the SRY. DNA was prepared from peripheral blood lymphocytes as well as from gonadal tissue preserved in a paraffin block. RESULTS: One hermaphrodite contained the SRY sequences in peripheral blood lymphocytes and the testicular part of ovotestis tissue preserved in a paraffin block, while in the second patient these sequences were not detected. CONCLUSIONS: The SRY positive subject resulted from occult Y mosaicism rather than from X-Y translocation. Testis differentiation in the SRY negative subject may have been caused by mutation of a gene on the X chromosome or, alternatively, on an autosome.

Disorders of Sex Development↗