PubMed Health⌕ Search

Biomedical subjects

T Hayakawa

Publications and source records attributed to T Hayakawa.

At least 19 recordsLinked to original sources
PubMed1992

Microtubule-independent choleresis and anti-cholestatic action of tauroursodeoxycholate in colchicine-treated rat liver.

In order to cast light on the anti-cholestatic and cytoprotective properties of ursodeoxycholic acid (UDCA), intrahepatic transport and secretion of bile salts and biliary phospholipids were investigated by using isolated perfused livers from colchicine-pretreated rats. Administration of taurocholic acid (TCA) after colchicine pretreatment induced marked cholestasis. Tauroursodeoxycholic acid (TUDCA) treatment, in contrast, was associated with maintenance of bile flow, with excretion rates of bile acids and phospholipids similar to those in control animals. Furthermore, TCA-induced cholestasis in colchicine-treated rat livers was clearly decreased by co-administration of TUDCA. Although simultaneous addition of UDCA also showed slight improvement, with or without taurine pre-treatment, biliary bile-salt analysis also showed that cholestasis was markedly remitted as the excretion of taurine-conjugated UDCA was increased. The results suggest that the cytoprotective and anti-cholestatic effects of TUDCA may be linked to action at the intrahepatocyte level, represented by mild detergent effects on organelle lipids and preservation of intracellular transport even under microtubule-dysfunctional conditions. In addition, it was indicated that cytoprotective effects of UDCA may also be exerted after its conjugation with taurine inside hepatocytes.

Animals↗
PubMed1992

Matrix metalloproteinase 9 (92-kDa gelatinase/type IV collagenase) from HT 1080 human fibrosarcoma cells. Purification and activation of the precursor and enzymic properties.

Matrix metalloproteinase 9 (MMP-9) has been purified as an inactive zymogen of M(r) 92,000 (proMMP-9) from the culture medium of HT 1080 human fibrosarcoma cells. The NH2-terminal sequence of proMMP-9 is Ala-Pro-Arg-Gln-Arg-Gln-Ser-Thr-Leu-Val-Leu-Phe-Pro, which is identical to that of the 92-kDa type IV collagenase/gelatinase. The zymogen can be activated by 4-aminophenylmercuric acetate, yielding an intermediate form of M(r) 83,000 and an active species of M(r) 67,000, the second of which has a new NH2 terminus of Met-Arg-Thr-Pro-Arg-(Cys)-Gly-Val-Pro-Asp-Leu-Gly-Arg-Phe-Gln-Thr- Phe-Glu. Immunoblot analyses demonstrate that this activation process is achieved by sequential processing of both NH2- and COOH-terminal peptides. TIMP-1 complexed with proMMP-9 inhibits the conversion of the intermediate form to the active species of M(r) 67,000. The proenzyme is fully activated by cathepsin G, trypsin, alpha-chymotrypsin, and MMP-3 (stromelysin 1) but not by plasmin, leukocyte elastase, plasma kallikrein, thrombin, or MMP-1 (tissue collagenase). During the activation by MMP-3, proMMP-9 is converted to an active species of M(r) 64,000 that lacks both NH2- and COOH-terminal peptides. In addition, HOCl partially activates the zymogen by reacting with an intermediate species of M(r) 83,000. The enzyme degrades type I gelatin rapidly and also cleaves native collagens including alpha 2 chain of type I collagen, collagen types III, IV, and V at undenaturing temperatures. These results indicate that MMP-9 has different activation mechanisms and substrate specificity from those of MMP-2 (72-kDa gelatinase/type IV collagenase).

Amino Acid Sequence↗
PubMed1992

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 3 (stromelysin-1) using monoclonal antibodies.

A one-step sandwich enzyme immunoassay (EIA) for matrix metalloproteinase 3 (MMP-3; stromelysin-1) was developed. The assay system used two simultaneous immunoreactions using a solid phase monoclonal antibody and a horseradish peroxidase-labeled monoclonal antibody (Fab'). The sensitivity of the assay system was 20 micrograms/l and linearity was obtained between 31 and 500 micrograms/l. The EIA system was capable of measuring both precursor and active forms of MMP-3 as well as the forms of MMP-3 complexed with tissue inhibitors of metalloproteinases. MMP-3 levels as measured by this assay are significantly higher in the sera of patients with rheumatoid arthritis as compared to those of healthy subjects and patients with osteoarthritis. Immunoblot analyses showed that in the sera and synovial fluids of patients with rheumatoid arthritis, MMP-3 is present in the 59- and 57-kDa precursor forms.

Animals↗
PubMed1992

Genetically engineered rice resistant to rice stripe virus, an insect-transmitted virus.

The coat protein (CP) gene of rice stripe virus was introduced into two japonica varieties of rice by electroporation of protoplasts. The resultant transgenic plants expressed the CP at high levels (up to 0.5% of total soluble protein) and exhibited a significant level of resistance to virus infection. Plants derived from selfed progeny of the primary transformants also expressed the CP and showed viral resistance, indicating stable transmission of the CP gene and the trait of resistance to the next generation. Moreover, the virally encoded strip disease-specific protein was not detected in transgenic plants expressing CP 8 weeks after inoculation, indicating protection before viral multiplication. These studies demonstrated that CP-mediated resistance to virus infection can be extended to cereals and to the viruses transmitted by an insect vector (planthopper).

Base Sequence↗
PubMed1992

Myristoylation-dependent membrane targeting and release of the HTLV-I Gag precursor, Pr53gag, in yeast.

The unprocessed HTLV-I Gag precursor, Pr53gag, was synthesized in yeast, Saccharomyces cerevisiae. The synthesized Pr53gag was myristoylated, associated with the cellular membrane, and released into the culture medium. The released Pr53gag was pelleted by centrifugation at 100,000 x g for 2 h. Conversion of Gly2 to Ala allowed synthesis of a non-myristoylated soluble Pr53gag which was not released into the culture medium. These results suggest that the release of the HTLV-I Gag precursors Pr53gag, occurs in yeast in a myristoylation-dependent manner.

Amino Acid Sequence↗
PubMed1992

Protective effect of NGF atelocollagen mini-pellet on the hippocampal delayed neuronal death in gerbils.

Very recently, contradictory results were presented as to the effects of exogenous nerve growth factor (NGF) on the hippocampal delayed neuronal necrosis following transient ischemia. In the present study, we administered a large amount of NGF with the atelocollagen mini-pellet system, measured the local NGF contents, and evaluated the effect of this neurotrophic factor on the postischemic hippocampal pyramidal cells in gerbils. We concluded that the exogenous NGF, when given continuously at sufficient concentrations, prevents pyramidal cell damage. The possible cause of discrepancy in previous studies is discussed.

Animals↗
PubMed1992

Requirement of N- and C-terminal regions for enzymatic activity of human T-cell leukemia virus type I protease.

The requirement of N- and C-terminal regions for the enzymatic activity of human T-cell leukemia virus type I (HTLV-I) protease was investigated using a series of deletion mutants. The activity was analyzed by autoprocessing of the protease itself or by processing of the gag p53 precursor. The deletional analyses indicated that Asp38-Gly152 with an additional Met-Pro sequence at the N-terminus was probably sufficient for the enzymatic activity, although the mature HTLV-I protease consists of Pro33-Leu157. A molecular model of HTLV-I protease, which was constructed by comparison with the structure of Rous sarcoma virus protease, predicted that Pro33-Leu37 and Gly143-Leu147 would form a beta-sheet. Our experimental results and the model structure suggest that (a) five amino acids in the N-terminal region (Pro33-Leu37), which are thought to be involved in the beta-sheet, are not crucial for the enzymatic activity; (b) Pro153-Leu157 is not necessary but Pro148-Gly152 is important for the enzymatic activity, in addition to Gly143-Leu147 involved in the beta-sheet.

Amino Acid Sequence↗
PubMed1992

Papaverine inhibits transcytotic vesicle transport and lipid excretion into bile in isolated perfused rat liver.

Papaverine is a nonspecific smooth muscle relaxant and a phosphodiesterase inhibitor. Its effects on biliary excretion of lipids and horseradish peroxidase were investigated in a single-pass isolated perfused rat liver model. A constant infusion of papaverine (1.6 mumol/min; 40 mumol/L) significantly increased bile flow (microliters per minute per gram of liver) before (2.03 +/- 0.09 vs. 1.0 +/- 0.06) and after sodium taurocholate infusion (2.77 +/- 0.10 vs. 1.88 +/- 0.11). However, papaverine significantly and reversibly reduced biliary excretion of phospholipids and cholesterol (nanomoles per minute per gram of liver) after a 1.0 mumol/min sodium taurocholate infusion, from 7.45 +/- 0.83 and 1.42 +/- 0.15 to 1.75 +/- 0.18 and 0.39 +/- 0.06, respectively (p less than 0.01), whereas secretion of bile acids was unaffected. When a 1-min pulse of horseradish peroxidase (25 mg) was infused in isolated perfused rat liver after a continuous infusion of N6,O-2'-dibutyryladenosine 3',5'-cyclic monophosphate (0.25 mumol/min; 6.25 mumol/L), horseradish peroxidase appeared in bile in an early (4 to 6 min) and late (20 to 25 min) peak. Papaverine significantly reduced the late peak, from 1.211 +/- 0.264 to 0.498 +/- 0.107 (p less than 0.01). Papaverine had no significant effects on either cyclic AMP or cyclic GMP in the liver and bile, although it has been reported that papaverine is a phosphodiesterase inhibitor. These findings indicate that papaverine inhibits biliary excretion of lipids but not bile acids, and they suggest that papaverine has an inhibitory effect on transcytotic vesicle transport independent of an increase of cyclic nucleotides in hepatocytes.

Animals↗
PubMed1992

Enzyme immunoassay and immunochemical characterization of pancreatic stone protein in human serum.

Monoclonal antibodies were raised against human pancreatic stone protein (PSP) and used for one-step enzyme immunoassay (EIA). PSP-S2-5 was employed as the standard in the assay. The assay's measurable range was 25-1,500 ng/ml and within run coefficient of variation was 3.7-6.4%. Analytical recovery of the assay was 101.5 +/- 5.65% (mean +/- SD). The results of experiments in which serum was fractionated by Mono S (cation exchange chromatography) suggested that most of immunoreactive material in human serum is PSP-S2-5. The EIA offers simple, rapid, and specific analysis of serum PSP level for clinical diagnosis.

Antibodies, Monoclonal↗
PubMed1992

Enzyme immunoassay for specific analysis of pancreatic stone proteins in human pancreatic juice.

In order to study the concentration of pancreatic stone protein (PSP) in human pancreatic juice, we investigated the influence of the insoluble form of PSP-S1 converted from PSP-S2-5 on PSP determination and the assay method for PSP-S1 precipitate after solubilizing PSP-S1. When bovine trypsin was added to pancreatic juice, PSP-S1 was converted from PSP-S2-5 and precipitated about 45-85% after 1 h. The precipitated PSP-S1 was dissolved in 0.1 M sodium acetate buffer, pH 4.0, and the concentration was measured by the enzyme immunoassay, with similar reactivity to PSP-S1 and PSP-S2-5. The proposed method can offer accurate and specific analysis of the PSP level in pancreatic juice. The results of the fractionation of pancreatic juice and duodenal juice on Mono S cation-exchange chromatography suggested that the major component of PSP was PSP-S2-5 in pancreatic juice and PSP-S1 in duodenal juice.

Calcium-Binding Proteins↗
PubMed1992

Measurements of CSF biochemical tumor markers in patients with meningeal carcinomatosis and brain tumors.

CSF beta-glucuronidase, polyamines and carcinoembryonic antigen (CEA) were analyzed in 16 patients with meningeal carcinomatosis from solid tumor in systemic organs, 27 with benign brain lesions, 18 with primary brain tumors, 14 with metastatic brain tumors and 5 with leptomeningeal dissemination of other malignant diseases. Beta-glucuronidase levels in all cases of meningeal carcinomatosis, meningeal gliomatosis and meningeal lymphoma were higher than 100 micrograms/dl/hr; on the other hand, levels in all cases of benign brain lesions were below 100 micrograms/dl/hr. Levels of beta-glucuronidase and polyamines were not high in the cases with positive cytology after tumor resection. Polyamine levels were below 0.05 nmol/ml in all cases after resection of the metastatic brain tumor. Cystic fluid of malignant tumors showed high levels of beta-glucuronidase and polyamines. On the other hand, the levels of polyamines in the cystic fluid of benign tumor were low, although the levels of beta-glucuronidase were high. Some cases of meningeal carcinomatosis with high levels of serum CEA did not show high levels of CSF CEA. For metastatic brain tumors, the cases with intraparenchymal tumors, especially with dural attachment showed high levels of beta-glucuronidase and CEA preoperatively, but they returned to normal after surgery. In cases of meningeal carcinomatosis treated by intrathecal chemotherapy with methotrexate (MTX) and cytosine arabinoside (Ara-C), CSF beta-glucuronidase reflected the neurological status better than the cell count decreased rapidly following chemotherapy and beta-glucuronidase was considered as a useful CSF marker in cases of meningeal carcinomatosis to monitor the course of the disease. The same situation was observed in CSF CEA and CEA was also considered as a useful marker when CEA levels in CSF are higher than those in serum.

Antineoplastic Agents↗
PubMed1992

Effects of glucocorticoid and chemotherapy on the peritumoral edema and astrocytic reaction in experimental brain tumor.

To study the effects of glucocorticoids and chemotherapeutic agents on the pathophysiology of the tumor-induced brain edema, the site of Evans blue-albumin extravasation, the distribution of extravasated serum albumin, and the extent of local astrocytic reaction were examined in a rat model of implanted brain tumor. Experimental brain tumors were produced by implanting small pellets of Walker 256 carcinosarcoma into the cerebral cortex of Wistar rats. In the steroid group, rats were administered with intraperitoneal methylprednisolone succinate (15 mg/kg) daily on and after the 6th day postimplantation, and sacrificed on the 14th day. In the chemotherapy group, rats were given an intravenous injection of cyclophosphamide (30 mg/kg) on the 14th day, and sacrificed on the 21st day. Rats in the untreated group were sacrificed on the 14th day without any therapy. Each animal was sacrificed by the transcardiac perfusion with paraformaldehyde 30 min after intravenous injection of Evans blue. Firstly, coronal blocks of the brain were examined for Evans blue staining macroscopically. Paraffin embedded sections were studied for the Evans blue fluorescence and for the immunohistochemical reaction to serum albumin and GFAP. The examination of Evans blue demonstrated that the origin of extravasation of serum albumin was the tumor and the adjacent brain with dense tumor cell infiltration in any group of rats. The extravasated serum albumin distributed widely and the astrocytic reaction was prominent in the brain of the untreated group. A positive correlation was observed between the intensity of albumin immunoreaction and the degree of astrocytic proliferation. Chemotherapy effectively decreased the size of tumor and reduced the extravasation of serum albumin. The astrocytic reaction was however, not reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Diagnosis and treatment of patients with meningeal carcinomatosis.

The records of thirty-four patients with meningeal carcinomatosis treated at our hospital between 1984 and 1990 were reviewed. The sources, histologies, metastatic lesions outside the central nervous system, the history of the treatment of primary lesions and intraparenchymal of metastatic brain tumors and the period from the diagnosis of primary lesions and the treatment of intraparenchymal metastatic brain tumors to the diagnosis of meningeal carcinomatosis were investigated. Meningeal carcinomatosis was diagnosed and by neurological signs, CSF cytology, CT scan and MRI. Each patient was given a 5 mg single dose of methotrexate (MTX) alone or combined with 20 mg cytosine arabinoside (Ara-C) administered by intrathecal injection via an Ommaya reservoir and standard lumbar puncture with or without radiotherapy. Following intrathecal chemotherapy 22 of 29 patients showed symptomatic improvement of meningeal irritation and in 10 of 29 patients with cranial nerve impairment amelioration of symptoms was also observed. Moreover, CSF cytology became negative in 10 of 29 patients after a full course of intrathecal chemotherapy. Neurotoxicity Leukoencephalopathy, a neurotoxic effect of intrathecal chemotherapy was not observed in any of the patients. From these results, MTX in small doses is recommended for intrathecal chemotherapy of meningeal carcinomatosis to prevent neurotoxicity.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Ultrastructural study of ascending projections to the lateral mammillary nucleus of the rat.

We examined the synaptic organization of ascending projections from the pars ventralis of the dorsal tegmental nucleus of Gudden (TDV) and the laterodorsal tegmental nucleus to the lateral mammillary nucleus (LM). The LM neuropil consists of terminals containing pleomorphic synaptic vesicles and forming symmetric synaptic contact, and terminals containing round synaptic vesicles and forming asymmetric synaptic contact. They make up 63% and 37%, respectively, of all axodendritic terminals. All axosomatic terminals contain pleomorphic vesicles and make symmetric contact. Following injection of WGA-HRP into the TDV, many anterogradely labeled terminals and retrogradely labeled cells are found in the LM. Labeled terminals contact mainly proximal (more than 2 microns diameter) and intermediate (1-2 microns diameter) dendrites. Serial ultrathin sections of the LM show that 55% of axosomatic terminals are labeled anterogradely. Following injection of WGA-HRP into the laterodorsal tegmental nucleus, many anterogradely labeled terminals are found in the LM, but no retrogradely labeled cells are present. Labeled terminals contact mainly distal (less than 1 micron diameter) and intermediate dendrites as well as somata. In the LM neurons, 46% of axosomatic terminals are labeled anterogradely. All labeled terminals from these nuclei contain pleomorphic vesicles and make symmetric synaptic contact. These results indicate that almost all axosomatic terminals come from the TDV and the laterodorsal tegmental nucleus, which send inhibitory inputs to the lateral mammillary nucleus.

Animals↗
PubMed1992

Experimental study on the indications for barbiturate therapy. Change in haemodynamics and the influence of dopamine.

The effect of barbiturates on the cerebral haemodynamics and the influence of dopamine on barbiturates were investigated using 20 cats, and clinical indication of barbiturate therapy is discussed. Cerebral blood flow, oxygen extraction fraction, and cerebro-vascular resistance as well as physiological variables were evaluated at various concentrations of barbiturates in the blood. Thiamylal caused simultaneous reduction of mean arterial blood pressure and cerebral blood flow. As the disruption of autoregulation proceeded, cerebro-vascular resistance and oxygen extraction fraction increased till the barbiturate-induced coma stage. Furthermore, cerebro-vascular resistance increased much more markedly by the combined use of dopamine. Clinically, our results indicate barbiturates would increase cerebral circulatory disturbances caused by vasospasm following subarachnoid haemorrhage because barbiturates further increase cerebro-vascular resistance. Then again, the combined use of dopamine is not preferable because of deterioration in vasospasm.

Animals↗
PubMed1992

Peritoneal absorption of pancreatic enzymes in dogs.

To elucidate peritoneal absorption of pancreatic enzymes, plasma levels of amylase, lipase, and trypsinogen were measured after the intraperitoneal injection of 10 ml human pancreatic juice in dogs. Plasma pancreatic amylase, lipase, and trypsinogen were determined using the immunoassay specific to the corresponding human pancreatic enzyme to exclude cross-reaction with the endogenous enzyme activities of the canine plasma. Plasma immunoreactivity of human amylase persistently rose during 24 h after the injection, whereas elevation of plasma amylase enzyme activity become significant only at 24 h. Increase of plasma lipase was not remarkable. Significant increase of the immunoreactivity was observed only at 24 h but there was no significant increase of the enzyme activity during this period. Plasma trypsinogen immunoreactivity peaked at 2 h remained significantly elevated during 24 h. The transperitoneal absorption of pancreatic enzymes in dogs was confirmed using intraperitoneal injection of human pancreatic juice combined with immunoassay specific to human pancreatic enzymes.

Amylases↗