Biomedical subjects

S Kawamura

Publications and source records attributed to S Kawamura.

At least 73 records · Page 4Linked to original sources

PubMed1999

Zonal organization of the ventral lateral geniculate nucleus in the cat: cholera toxin mapping.

A zonal organization of the ventral lateral geniculate nucleus (LGNv) in the cat was studied with the bidirectional tracing method by using the subunit b of cholera toxin (CTb) as the marker. The prime objectives of the present study were to examine precise distribution of terminals of the retinal afferents to the LGNv, and to correlate it with the origins and terminations of the other central connections of the nucleus. The results obtained are summarized as follows: (1) the LGNv of the cat is divided into 3 zones according to the terminations of retinal afferents: lateral, intermediate, and medial; (2) the lateral zone receives afferents from the retina in which ipsi- and contralateral fibers terminate in a complementary fashion. According to the density of labeling of retinal terminals, the lateral zone is further divided into several areas. It also receives fibers from the visual related cortex; (3) the intermediate zone, which does not receive fibers from the retina nor the visual cortex, is reciprocally connected with the midbrain, primarily with the superficial layers of the superior colliculus (SC), and gives rise to thalamic projections to the nucleus centralis lateralis bilaterally; and (4) the medial zone, from which commissural fibers arise, receives afferents bilaterally from the retina, and sends fibers to the SC bilaterally. These results suggest that the LGNv of the cat has three different zones. Functional participation of each zone has been discussed.

Animals↗

PubMed1999

Calcium-dependent regulation of rhodopsin phosphorylation.

Depending on ambient light conditions, a rod photoreceptor cell adapts to a light stimulus. For example, when it is kept in the light, its light sensitivity decreases because of light adaptation. The adaptational state is regulated by the Ca2+ concentration in the cytoplasm ([Ca2+]i). The [Ca2+]i is high in the dark and becomes low when the cell is light-adapted. The change in [Ca2+]i is detected by several Ca(2+)-binding proteins that change their conformations by binding Ca2+. S-modulin, found in frog rods, or its bovine homologue recoverin, is a 23 kDa Ca(2+)-binding protein that inhibits rhodopsin phosphorylation at high Ca2+ concentrations by inhibiting rhodopsin kinase. Since rhodopsin phosphorylation is an inactivating mechanism for light-activated rhodopsin (R*), the inhibition of this reaction will prolong the lifetime of R*. In this way, S-modulin is expected to increase the efficiency of phototransduction and therefore the light-sensitivity of rods in the dark. When rods are light-adapted, [Ca2+]i decreases so that the lifetime of the R* is expected to reduce, resulting in a decrease in light sensitivity. Even though it is generally agreed that S-modulin inhibits rhodopsin phosphorylation, its physiological function is not yet well understood.

Adenosine Triphosphate↗

PubMed1999

High-resolution crystals of the HU mutant K38N from Bacillus stearothermophilus.

The DNA-binding protein HU is ubiquitous in the prokaryotic cell. It is a major protein component of isolated nucleoids and is believed to control the tertiary structure of prokaryotic DNA. The Bacillus stearothermophilus HU (BstHU) mutants obtained by mutagenesis have been investigated. Crystallization experiments of BstHU-K38N (Lys38 is substituted with Asn) resulted in two forms of crystals suitable for high-resolution x-ray analysis. The first form belongs to the monoclinic space group C2 with unit-cell dimensions of a = 90.1 A, b = 43.5 A, c = 63.7 A, and beta = 135.1 degrees, and it diffracts x rays to 1.5-A resolution. The second form belongs to the tetragonal space group I41 with a = b = 62.6 A and c = 43.3 A, and it diffracts up to 1.8-A resolution.

Bacterial Proteins↗

PubMed1999

Ruptured anterior spinal artery aneurysm: a case report.

BACKGROUND: Spinal artery aneurysms are rare, and are usually found in association with arteriovenous malformations or coarctation of the aorta. CASE REPORT: A 42-year-old man with a ruptured anterior spinal artery aneurysm is presented here. He experienced subarachnoid hemorrhage, which was confirmed by computed tomography. Magnetic resonance imaging revealed an aneurysm in front of the upper part of the medulla. Angiography demonstrated bilateral vertebral artery occlusion. Distal vertebral arteries and the basilar artery were perfused via the dilated anterior spinal artery, which originates in the right subclavian artery. The aneurysm was located at the distal part of the anterior spinal artery, and was successfully clipped through a lateral suboccipital craniotomy 2 months after bleeding from the aneurysm. After rehabilitation, the patient was able to walk with no apparent neurologic deficit. CONCLUSIONS: This case suggests that the anterior spinal artery as a collateral route after bilateral vertebral artery occlusion is under hemodynamic stress, resulting in aneurysm formation and rupture.

Adult↗

PubMed1999

Enzyme-linked immunosorbent assay detection of prostate-specific antigen messenger ribonucleic acid in prostate cancer.

OBJECTIVES: To develop a rapid, sensitive, reverse transcriptase-polymerase chain reaction (RT-PCR) prostate-specific antigen (PSA) messenger ribonucleic acid (mRNA) detection method by applying colorimetric enzyme-linked immunosorbent assay (ELISA). METHODS: Total RNA was extracted from 16 urogenital cancer cells (including PSA-producing LNCaP cells) from pelvic and inguinal lymph node aspiration biopsy samples from patients with prostate, bladder, and penile cancer, as well as from blood samples of 500 patients with urogenital cancer. We used rTth polymerase for RT and PCR. The RNA target was amplified by RT-PCR with dinitrophenyl-labeled primer. The PCR product was denatured and hybridized on a PSA-specific probe-coated microwell plate. RESULTS: In 1 6 cancer cell lines, only LNCaP cells expressed especially high PSA mRNA values, with an optical density (OD) greater than 3. In other cell lines, two testicular cells had relatively high ODs, 1.909 and 0.987, respectively. A high PSA mRNA value was obtained by fine needle aspiration from pelvic lymph node specimens of cytologically positive lymph nodes from patients with prostate cancer but not from patients with cytologically proved bladder or penile cancer. Sensitivity and specificity of fine needle aspiration samples were 70% and 100%, respectively. Blood tests obtained from patients with prostate cancer demonstrated high PSA mRNA values. CONCLUSIONS: The PSA mRNA RT-PCR ELISA method provides a sensitive photometric enzyme immunoassay for the detection of PSA mRNA, using nonradioactive techniques.

Enzyme-Linked Immunosorbent Assay↗

PubMed1999

Pathological evaluation of steroid withdrawal in pediatric renal transplant recipients.

Protocol biopsies were performed to detect and treat subclinical rejection in eight living related pediatric renal transplant recipients who had been withdrawn from steroids. Low-grade tubulitis (t1) and mononuclear cell interstitial inflammation (i1), typical of borderline rejection and low-grade interstitial fibrosis (ci1), and tubular atrophy (ct1), characteristic of chronic rejection, appeared frequently in protocol biopsies more than 3 yr after steroid withdrawal. In contrast, early-type glomerulitis (g), allograft glomerulopathy (cg), arteriolar hyaline thickening (ah), intimal arteritis (v), and fibrous intimal thickening (cv) were not observed in protocol biopsies after steroid withdrawal. Low-dose pulse therapy (methylprednisolone (MP) 250 or 500 mg/d for 3 d) was administered to five patients for borderline and/or acute grade 1a rejection, as determined by protocol biopsies in the absence of clinical rejection. No oral steroids were administered. Renal function in all patients remained satisfactory, without proteinuria, in follow-up periods ranging from 22 to 68 months after steroid withdrawal. Of the eight patients, three grew to almost normal height (> mean -2SD) and four exhibited catch-up growth. Thus, steroid withdrawal can be safe and improves growth in pediatric renal transplant recipients if undertaken with careful clinical follow-up, including protocol biopsies.

Biopsy↗

PubMed1999

Heat shock protein 70 (hsp70) as a major target of the antibody response in patients with pulmonary cryptococcosis.

Cryptococcus neoformans causes infection in individuals with defective T cell function, such as AIDS, as well as without underlying disease. It has been suggested that humoral as well as cellular immunity might play an important role in the immune response to C. neoformans infection. We have recently shown, using immunoblotting, that the 70-kD hsp family of C. neoformans was the major target molecule of the humoral response in murine pulmonary cryptococcosis. In this study we also used immunoblotting to define the antibody responses in the sera of 24 patients with pulmonary cryptococcosis: 21 proven and three suspected diagnoses. Anti-C. neoformans hsp70 antibody was detected in 16 of 24 (66.7%) patients with pulmonary cryptococcosis. Fourteen of 17 (82.3%) patients with high antigen titres (> or = 1:8) and two of seven (28.6%) patients with low titres (< or = 1:4) had detectable levels of anti-hsp70 antibody. Sera from patients positive for anti-hsp70 antibody showed high titres in the Eiken latex agglutination test for the detection of serum cryptococcal antigen. Our results indicate that the 70-kD hsp family from C. neoformans appears to be a major target molecule of the humoral response, not only in murine pulmonary cryptococcosis, but also in human patients with pulmonary cryptococcosis.

Adult↗

PubMed1999

Complete nucleotide sequence, origin of isoform and functional characterization of the mouse hepsin gene.

Hepsin, a type-II membrane-associated serine protease, has been implicated in cell growth and development as well as possible initiation of blood coagulation. Here, we report on the complete nucleotide sequence, functional characterization of key structural features and the promoter of the mouse hepsin gene. The gene has a size of approximately 17 kb, and is composed of 12, 13, or 14 exons depending on alternative intron splicings - one in the 5'-UTR and the other two in the second intron. The latter two, which occur in approximately half of the hepsin transcripts, generate a hepsin mRNA species with an extra exon, which is responsible for producing a hepsin isoform with a unique 20-residue sequence inserted in the cytoplasmic portion of hepsin. Most hepsin transcripts have the 5'-UTR intron spliced, and its splicing can occur independently of the other alternative splicings. The transcriptional initiation site was determined to be 636 bp upstream of the first ATG site in a cytidine-rich region. The 5'-flanking region of hepsin up to nucleotide 274 showed a substantial promoter activity in HepG2 cells, with its expression activity sevenfold higher in the presence of the 5'-UTR intron sequence in comparison to that without the intron sequence. The basal promoter region contains potential binding sites for several transcription factors including SP1, AP2, C/EBP, LF-A1, and E box, which may be responsible for ubiquitous, but liver- and kidney-preferred tissue expression of the hepsin gene.

Alternative Splicing↗

PubMed1999

The significance of resections for residual masses after chemotherapy in metastatic testicular tumors.

BACKGROUND: After chemotherapy for metastatic testicular tumors, masses may remain, often in the metastatic sites. This study analyses the role of resections for the residual masses. METHODS: Seventy-seven patients with advanced (stage II, III) testicular tumors were treated. Of these, 38 patients, including eight with seminoma and 30 patients with non-seminomatous germ cell tumors, underwent resection of residual masses after chemotherapy and have been followed for a median of 41.5 months (range 2-138) after the resection. RESULTS: Residual masses were necrosis/fibrosis in 19 patients, mature teratoma in 11 and cancer in eight. The ratio of cancer in stage III (41.2%) was significantly higher than that in stage II (4.8%). Ten of 38 (26.3%) patients experienced recurrences in sites other than the resected sites, and five of 10 patients have died of cancer. Most recurrences (80%) occurred within two years. Recurrences after resection were detected in 4.8% of stage II patients, 52.9% of stage III, 16.7% of necrosis/fibrosis and mature teratoma, and 62.5% of cancer. The survival rate of patients with cancer was significantly lower in spite of adjuvant chemotherapy after surgery. CONCLUSIONS: Resection for residual masses after chemotherapy in metastatic testicular tumors was useful in confirming the tissue and in controlling the metastatic sites. Recurrences were often found in patients with cancer in the residual mass and the prognosis of patients with cancer was poor, therefore the development of more effective therapy for patients with cancer is required to improve the prognosis.

Adolescent↗

PubMed1999

Severe rhabdomyolysis as a complication of high-dose chemotherapy in a patient with advanced testicular cancer.

BACKGROUND: A 38-year-old man was diagnosed with choriocarcinoma in the left testis, a 9 cm retroperitoneal tumor, left hydronephrosis, multiple lung metastasis and gynecomastia. His serum hCG level decreased but was still above the normal range after four courses of standard chemotherapy. METHODS: High-dose chemotherapy was then given with ICE (ifosfamide, carboplatin, etoposide) from days -7 to-3. RESULTS/DISCUSSION: On day -2 the patient became confused and hallucinated, so the sedatives haloperidol and flunitrazepam were administrated. His creatinine phosphokinase levels increased to 6150 IU/L (reference range <197 IU/L) on day 0. Myoglobinuria and myoglobinemia were noted and the renal dysfunction progressed. A peripheral blood stem cell transplantation was performed after hemodialysis on day 0. Although his bone marrow recovered, the patient died of respiratory failure on day 18. An autopsy revealed massive pulmonary bleeding. Pretreatment renal dysfunction, renal damage by high-dose chemotherapy, ifosfamide-induced hallucinations and the administration of sedatives, such as haloperidol and flunitrazepam, may have been causative factors for the rhabdomyolysis observed in this patient.

Adult↗

PubMed1999

Neoadjuvant therapy and bladder substitute for invasive bladder cancer: 20 years experience at Tohoku University.

BACKGROUND: Neobladder, using the intestine, was performed after neoadjuvant therapy and total cystectomy as a treatment for invasive bladder cancer. METHODS: Between January 1977 and April 1997, an ileocecal neobladder was used for 23 patients and a sigmoid neobladder was chosen for use in 32 patients. For the diagnosis of invasive bladder cancer and the evaluation of neoadjuvant therapy, we used whole-layer core biopsy (WLCB) of the bladder tumor and fine needle aspiration biopsy (FNAB) of pelvic lymph nodes after bipedal lymphography. For neoadjuvant therapy, two to four courses of internal iliac arterial infusion chemotherapy (IIA) were undertaken in 32 patients. Five patients were treated with IIA combined with 40 Gy irradiation to the pelvic space. RESULTS: Pretreatment WLCB revealed a tumor of stage T2b or greater in 10 patients. After neoadjuvant therapy, three patients were down-staged to pT0. In five patients, pretreatment FNAB revealed pelvic lymph node metastases that were not detected by computed tomography or magnetic resonance imaging. Fine needle aspiration biopsy post-neoadjuvant therapy revealed tumor stage N0 in all patients and lymph node dissection revealed pN0 in four patients. Of the five patients who received 40 Gy irradiation, none had any postoperative complications, such as intestinal fistula or urinary leakage. Four male patients (10%) had urethral recurrence, but all were successfully treated by transurethral resection. Two patients treated prior to 1985 experienced local recurrence. Neither was treated by neoadjuvant therapy. Eight patients who died after 1985 had metastatic cancer, but none had local recurrence. None of the patients who received a sigmoid neobladder required clean intermittent catheterization or had bilateral vesico-ureteral reflux. CONCLUSIONS: Neoadjuvant therapy seems to reduce local recurrence in invasive bladder cancer. The sigmoid colon may be suitable for neobladder.

Adult↗

PubMed1999

Genetic analyses of visual pigments of the pigeon (Columba livia).

We isolated five classes of retinal opsin genes rh1(Cl), rh2(Cl), sws1(Cl), sws2(Cl), and lws(Cl) from the pigeon; these encode RH1(Cl), RH2(Cl), SWS1(Cl), SWS2(Cl), and LWS(Cl) opsins, respectively. Upon binding to 11-cis-retinal, these opsins regenerate the corresponding photosensitive molecules, visual pigments. The absorbance spectra of visual pigments have a broad bell shape with the peak, being called lambdamax. Previously, the SWS1(Cl) opsin cDNA was isolated from the pigeon retinal RNA, expressed in cultured COS1 cells, reconstituted with 11-cis-retinal, and the lambdamax of the resulting SWS1(Cl) pigment was shown to be 393 nm. In this article, using the same methods, the lambdamax values of RH1(Cl), RH2(Cl), SWS2(Cl), and LWS(Cl) pigments were determined to be 502, 503, 448, and 559 nm, respectively. The pigeon is also known for its UV vision, detecting light at 320-380 nm. Being the only pigments that absorb light below 400 nm, the SWS1(Cl) pigments must mediate its UV vision. We also determined that a nonretinal P(Cl) pigment in the pineal gland of the pigeon has a lambdamax value at 481 nm.

Amino Acid Sequence↗

PubMed1999

Synthesis and DNA-binding of acridine-netropsin hybrid molecules.

We have designed and synthesized acridine-netropsin hybrid molecules. Spectroscopic (absorption, CD, flow dichroism and fluorescence) measurements reveal that hybrid molecules interact with DNA by both intercalation and minor-groove binding and shows enhanced preference for AT-rich sites.

Acridines↗

PubMed1999

Molecular modeling of single polypeptide chain of calcium-binding protein p26olf from dimeric S100B(betabeta).

P26olf from olfactory tissue of frog, which may be involved in olfactory transduction or adaptation, is a Ca2+-binding protein with 217 amino acids. The p26olf molecule contains two homologous parts consisting of the N-terminal half with amino acids 1-109 and the C-terminal half with amino acids 110-217. Each half resembles S100 protein with about 100 amino acids and contains two helix-loop-helix Ca2+-binding structural motifs known as EF-hands: a normal EF-hand at the C-terminus and a pseudo EF-hand at the N-terminus. Multiple alignment of the two S100-like domains of p26olf with 18 S100 proteins indicated that the C-terminal putative EF-hand of each domain contains a four-residue insertion when compared with the typical EF-hand motifs in the S100 protein, while the N-terminal EF-hand is homologous to its pseudo EF-hand. We constructed a three-dimensional model of the p26olf molecule based on results of the multiple alignment and NMR structures of dimeric S100B(betabeta) in the Ca2+-free state. The predicted structure of the p26olf single polypeptide chain satisfactorily adopts a folding pattern remarkably similar to dimeric S100B(betabeta). Each domain of p26olf consists of a unicornate-type four-helix bundle and they interact with each other in an antiparallel manner forming an X-type four-helix bundle between the two domains. The two S100-like domains of p26olf are linked by a loop with no steric hindrance, suggesting that this loop might play an important role in the function of p26olf. The circular dichroism spectral data support the predicted structure of p26olf and indicate that Ca2+-dependent conformational changes occur. Since the C-terminal putative EF-hand of each domain fully keeps the helix-loop-helix motif having a longer Ca2+-binding loop, regardless of the four-residue insertion, we propose that it is a new, novel EF-hand, although it is unclear whether this EF-hand binds Ca2+. P26olf is a new member of the S100 protein family.

Amino Acid Sequence↗

PubMed1999

Calpain inhibitor-1 reduces infarct size and DNA fragmentation of myocardium in ischemic/reperfused rat heart.

Myocardial ischemia/reperfusion activates a calcium-dependent protease, calpain, in the ischemic myocytes. It is not known whether calpain is involved in the mechanism of ischemia/reperfusion injury in hearts. Thus the purpose of this study was to clarify the effect of a selective calpain inhibitor (CAI) on infarct size and the extent of DNA damage in ischemic/reperfused rat hearts. Rats were divided in four groups (n = 7 each). In saline group, 0.3 ml of saline was administered (i.v.) 10 min before 30-min coronary occlusion followed by 6-h reperfusion. In vehicle group, 0.3 ml of 10% dimethyl sulfoxide (DMSO) was administered 10 min before the 30-min ischemia. CAI (0.5 mg/kg) was administered 10 min before the 30-min ischemia (CAI-A group) and 10 min before the 6-h reperfusion period (CAI-B group). Infarct size was detected with triphenyl tetrazolium chloride, and DNA fragmentation was detected by agarose gel electrophoresis and by in situ nick end labeling (ISEL). Infarct size was significantly smaller in the CAI-A group compared with the vehicle group (13+/-9% vs. 48+/-12%; p < 0.01), and the incidence of ISEL-positive myocyte nuclei in the subendocardial region was significantly reduced in the CAI-A group compared with the vehicle group (26+/-3% vs. 59+/-6%; p < 0.01). However, the effects of CAI in CAI-B group were not significant. Activation of calpain is involved in the mechanism of ischemia/reperfusion injury, and the preischemic administration of CAI was effective in reducing myocardial infarct size and the DNA damage of the myocytes in ischemic/reperfused rat heart.

Animals↗

PubMed1999

Comparison between PCR and detection of antigen in sera for diagnosis of pulmonary aspergillosis.

We evaluated the usefulness of PCR and antigen detection for the diagnosis of pulmonary aspergillosis. Forty-four serum samples from patients with pulmonary aspergillosis (33 with pulmonary aspergilloma, 4 with allergic bronchopulmonary aspergillosis, 4 with invasive pulmonary aspergillosis, and 3 with aspergillus pyothorax) were used in this study. PCR detection of Aspergillus DNA in serum samples was successful in 39 patients. Galactomannan antigen was detected by sandwich enzyme-linked immunosorbent assay in 25 patients and by latex agglutination test in 13 patients. Detection of Aspergillus DNA in serum samples by nested PCR had the highest sensitivity of the three methods tested for the diagnosis of pulmonary aspergillosis.

Antigens, Fungal↗

PubMed1999

Ischemic preconditioning attenuates apoptosis through protein kinase C in rat hearts.

To investigate the role of protein kinase C (PKC) in the mechanism of ischemic preconditioning (IP), infarct size and the incidence of apoptosis caused by ischemia-reperfusion were tested in four groups of Sprague-Dawley rats. Dimethyl sulfoxide (vehicle) or calphostin C (0.1 mg/ml) was administered 5 min before the 30-min coronary occlusion followed by a 6-h reperfusion. Three cycles of 3 min of ischemia followed by 3 min of reperfusion was performed as IP before the 30-min ischemia followed by a 6-h reperfusion with or without calphostin C pretreatment. Infarct size defined by triphenyltetrazolium chloride staining was reduced from 60 +/- 2 to 26 +/- 2% by IP (P < 0.01), but the effect of IP was abolished by calphostin C (51 +/- 3%). Apoptosis defined by in situ terminal deoxynucleotidyl transferase end-labeling (TUNEL) was reduced by IP from 44 +/- 3 to 13 +/- 2% in the subendocardial region (P < 0.01). This effect of IP was abolished by calphostin C (42 +/- 8%). Thus the effect of IP on reducing the infarct size and the incidence of apoptosis are both mediated by PKC in rat hearts.

Animals↗

PubMed1999

Arginine-55 in the beta-arm is essential for the activity of DNA-binding protein HU from Bacillus stearothermophilus.

DNA-binding protein HU (BstHU) from Bacillus stearothermophilus is a homodimeric protein which binds to DNA in a sequence-nonspecific manner. In order to identify the Arg residues essential for DNA binding, four Arg residues (Arg-53, Arg-55, Arg-58, and Arg-61) within the beta-arm structure were replaced either by Gln, Lys, or Glu residues, and the resulting mutants were characterized with respect to their DNA-binding activity by a filter-binding analysis and surface plasmon resonance analysis. The results indicate that three Arg residues (Arg-55, Arg-58, and Arg-61) play a crucial role in DNA binding as positively charged recognition groups in the order of Arg-55 > Arg-58 > Arg-61 and that these are required to decrease the dissociation rate constant for BstHU-DNA interaction. In contrast, the Arg-53 residue was found to make no contribution to the binding activity of BstHU.

Arginine↗