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Biomedical subjects

T Shimokawa

Publications and source records attributed to T Shimokawa.

At least 55 records · Page 3Linked to original sources
PubMed1999

Technology to obtain sustained release characteristics of drugs after delivered to the colon.

To determine the necessary technology by which sustained drug release is obtained after drug is delivered to the colon, two kinds of microcapsules were prepared and were filled in a pressure-controlled colon delivery capsule (PCDC). As a model drug 5-aminosalicylic acid (5-ASA) was used, because the target site of 5-ASA is the entire large intestine. 5-ASA was microencapsulated using a water-insoluble polymer, ethylcellulose (EC) or with pH-sensitive polymers, Eudragit L-100 or S-100 and encased in PCDC. The particle size of these microcapsules was around 800 microns and the loading efficiencies of 5-ASA were approximately 90%. In vitro dissolution tests were performed with the prepared microcapsules. The release rate of 5-ASA from the microcapsules was significantly prolonged as compared to 5-ASA powder, although there were no significant differences in the release rates between these microcapsules. By incorporating the 5-ASA microcapsules into PCDC, sustained release PCDCs for colon delivery were prepared and in vivo evaluation was performed using beagle dogs. As a fast release colon delivery system, PCDCs were prepared with 5-ASA powder suspended in suppository base. After oral administration of the test preparations to beagle dogs, plasma 5-ASA concentrations were measured and sustained release characteristics of 5-ASA from the test preparations were evaluated from the plasma 5-ASA concentration-time profiles. The first appearance time of 5-ASA into the systemic circulation after oral administration were 3 h for all the colon delivery preparations and it was thought that these test preparations were delivered to the colon. Both EC microcapsules and Eudragit S-100/RS-100 microcapsules in PCDC showed longer the mean residence time MRT, 8.2 +/- 0.6 h and 8.7 +/- 0.9 h, than Eudragit L-100/RS-100 microcapsules in PCDC where the MRT was 6.6 +/- 0.2 h. Since PCDCs containing 5-ASA powder exhibited a MRT of 7.0 +/- 1.0 h, these two types of preparations have suggested sustained release characteristics.

Algorithms↗
PubMed1999

Characterization of norfloxacine release from tablet coated with a new pH-sensitive polymer, P-4135F.

A new pH-sensitive polymer, P-4135F, was evaluated as a colon delivery device for norfloxacine (NFLX) which is used for the therapy of patients with Vero toxin-producing Escherichia coli gastroenteritis. P-4135F has a dissolution threshold pH of 7.2 which is higher than the conventional pH-sensitive polymers, Eudragit S100 and L100. To compare the dissolution site of P-4135F coated tablets with other enteric polymer coatings, mini-tablets containing sodium fluorescein (FL) as a model drug were prepared by coating them with the three polymers. After oral administration of FL mini-tablets to rats, the first-appearance time, Ti, of FL into the systemic circulation was measured. The Tis were 0.7+/-0.2 h for Eudragit L100, 1.8+/-0.4 h for S100 and 2.0+/-0.3 h for P-4135F. Direct inspection of the dissolution process of the FL mini-tablets after oral administration to rats was performed by abdominal incision studies. All of the coated FL mini-tablets started to dissolve in the rat ileum. The dissolution sites were identified to be proximal to the ileocecal junction for P-4135F, at the middle part of the ileum for Eudragit S100 and at the proximal part of the ileum for Eudragit L100. NFLX tablets with different membrane thicknesses of P-4135F were prepared and were orally administered to beagle dogs. The colon delivery efficiency was evaluated by measuring the Ti of NFLX into the systemic circulation. The mean Tis were 1.33+/-0.33 h for 56.8+/-0.5 microm membranes, 3.75+/-0.25 h for 64.6+/-0.7 microm membranes, 4.00+/-1.00 h for 70.5+/-0.5 microm membranes and 3.00+/-1.00 h for 74.9+/-0.4 microm membranes. By comparing the Ti, 4.33+/-0.33 h, obtained after oral administration of NFLX in a pressure-controlled colon delivery capsule, and the colon arrival time, 3.5+/-0.3 h, determined by a sulfasalazine test in beagle dogs. P-4135F coated NFLX tablets appeared to dissolve and disintegrate before reaching the colon. Studies using rats and beagle dogs have suggested that P-4135F dissolves in the lower part of the small intestine, i.e., the ileum. These studies also suggest that this new polymer will be useful for the delivery of NFLX to the lower part of the small intestine.

Acrylic Resins↗
PubMed1999

[Exercise capacity in children late after aortic valve replacement using the Konno procedure].

Between 1980 and 1996, aortic valve replacements using the Konno procedure were performed in 10 patients. In order to assess the latent problems after this procedure, the exercise capacity was evaluated in 6 patients (3 males and 3 females). Exercise stress tests by a bicycle ergometer with ramp protocol were performed and gas exchange responses using the mixing chamber method were measured. The mean age at the time of operation was 6.6 years (range 3 to 11) and the mean age at the time of exercise test was 11.4 years (range 8 to 15). All patients were NYHA class I except 2 patients who had residual PH. Maximum oxygen consumptions were 37 to 39 ml/kg/min in males and 23 to 34 ml/kg/min in females. Maximum heart rates ranged from 166 to 184 bpm and O2 pulses ranged from 4.6 to 7.1 ml/beat/BSA. In the 2 patients who had residual pulmonary hypertension, HR bursting and O2 pulse plateau & decline occurred, which may indicate presence of decreased stroke volume. In conclusion, all patients late after the Konno procedure could tolerate exercise beyond respiratory compensation and there were no arrhythmia during exercise. HR was satisfactorily increased but maximum oxygen consumption was lowered at about 70% of the normal level.

Aortic Valve↗
PubMed1999

Function of poly(ADP-ribose) polymerase in response to DNA damage: gene-disruption study in mice.

To elucidate the biological functions of poly(ADP-ribose) polymerase (PARP, [EC 2.4.2.30]) in DNA damage responses, genetic and biochemical approaches were undertaken. By disrupting exon 1 of the mouse PARP gene by a homologous recombination, PARP-deficient mouse embryonic stem (ES) cell lines and mice could be produced without demonstrating lethality. PARP-/- ES cells showed complete loss of PARP activity and increased sensitivity to gamma-irradiation and an alkylating agents, indicating a physiological role for PARP in the response to DNA damage. p53, a key molecule in cellular DNA damage response, was found to stimulate PARP activity and became poly(ADP-ribosyl)ated in the presence of damaged DNA. However, PARP-/- ES cells showed p21 and Mdm-2 mRNA induction following gamma-irradiation, indicating that PARP activity is not indispensable for p21 and Mdm-2 mRNA induction in the established p53-cascade. On the other hand, in a reconstituted reaction system, purified PARP from human placenta suppressed the pRB-phosphorylation activity in the presence of NAD and damaged DNA. Human PARP expressed in E. coli showed a similar effect on pRB-phosphorylation activity of cdk2. These findings suggest a direct involvement of PARP in the regulation of cdk activity for cell-cycle arrest.

Animals↗
PubMed1999

Early treatment of CMV antigenemia with ganciclovir for prevention of fatal CMV disease in patients receiving marrow from HLA-matched unrelated donors.

The effect of early treatment of cytomegalovirus (CMV) antigenemia with ganciclovir (DHPG) for the prevention of CMV disease was evaluated in 25 patients with hematological malignancy who had received marrow from human leukocyte antigen-matched unrelated donors at our institution. CMV antigenemia occurred in 17 of 25 patients, a high rate of 68%, and was initially detected between 4 and 8 weeks after bone marrow transplantation (BMT) (median time 5 weeks). The incidence of CMV antigenemia was statistically higher in those patients given steroids or antithymocyte globulin (P < 0.01). All 17 CMV antigenemia-positive patients were treated with DHPG until antigenemia was cleared, and this treatment was resumed if antigenemia occurred. CMV antigenemia eventually became negative in all cases. One major drawback of DHPG was that leukopenia was observed in six patients (35%). CMV disease occurred in six patients despite early treatment of CMV antigenemia with DHPG (24%, 6 of 25 patients). Four of them developed CMV disease in the early phase (within six months) and two in the late phase (more than six months). All CMV diseases in the early phase were easily cured by treatment with DHPG while monitoring CMV antigenemia, but CMV disease in the late phase did not respond to DHPG and led to the death of one patient. On the other hand, there were no patients who developed CMV disease in the antigenemia-negative group. Thus, although early treatment using our method was effective in clearing CMV antigenemia in unrelated BMT, it did not totally prevent CMV disease. A further method of early treatment for the prevention of fatal CMV disease is required.

Adolescent↗
PubMed1999

Regulation of murine protein C gene expression in vivo: effects of tumor necrosis factor-alpha, interleukin-1, and transforming growth factor-beta.

Protein C is a precursor of the anticoagulant serine protease, activated protein C, which inhibits coagulation factors Va and VIIIa. Although the liver appears to be the primary site of protein C synthesis, we previously demonstrated that the kidney and male reproductive organs also expressed abundant protein C mRNA in the mouse. In the present study, we further investigated the effects of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and transforming growth factor-beta (TGF-beta) on the expression of protein C mRNA in the principal producing organs, i.e., the liver, kidney, and testis. Both quantitative reverse transcription-PCR assay and in situ hybridization analysis revealed that TNF-alpha decreased protein C mRNA expression in the liver, kidney, and testis. IL-1 also down-regulated protein C mRNA expression in the liver and testis, but not in the kidney. In contrast, TGF-beta unchanged the expression level of protein C mRNA in these three organs. These observations suggest that TNF-alpha and IL-1 may contribute to an increase in the procoagulant potential by downregulation of protein C synthesis in the tissues during inflammatory processes.

Animals↗
PubMed1999

A new marrow T cell depletion method using anti-CD6 monoclonal antibody-conjugated magnetic beads and its clinical application for prevention of acute graft-vs.-host disease in allogeneic bone marrow transplantation: results of a phase I-II trial.

We established a simple method of T cell depletion using anti-CD6 monoclonal antibody-conjugated immunomagnetic beads. Preliminary experiments using this method demonstrated that CD3+ T cells could be partially depleted without depleting CD56+ NK cells. A phase I-II clinical study was performed to assess the safety and efficacy of this partial T cell depletion method for the prevention of acute graft-vs.-host disease (GVHD) in 10 leukemia patients at high risk for GVHD (defined as 1) unrelated transplant from MLC-positive or HLA-DRB1 mismatched donor or 2) related transplant from serologically HLA-A, -B, or -DR one-locus mismatched donor). Cyclosporine (CSP) and methotrexate (MTX) were used for additional prophylaxis against GVHD in all cases. Sustained engraftment occurred in 9 of the 10 patients. Although acute GVHD developed in 6 of the 9 evaluable patients, none developed more than grade III severe acute GVHD. Five patients were alive in remission at a median follow-up of 32 months after bone marrow transplantation, and no relapse of leukemia was observed. We conclude from this pilot study that selective T cell depletion with anti-CD6 monoclonal antibody coupled with CSP and MTX posttransplant immunosuppressive therapy is safe. Further analysis of the phase II-III study is needed to confirm the effectiveness of this protocol.

Acute Disease↗
PubMed1998

New preparation method of intestinal pressure-controlled colon delivery capsules by coating machine and evaluation in beagle dogs.

A new method for preparing large amounts of pressure-controlled colon delivery capsules (PCDCs) which employs a pharmaceutical coating machine, Hicoater-mini, has been developed. In contrast to our original method for preparing PCDCs where the inner surfaces of gelatin capsule were coated with the water-insoluble polymer ethylcellulose (EC), PCDC were directly prepared by coating the capsular shaped suppositories with EC. As a model drug, fluorescein (FL) was used in this study. FL powder was suspended with the suppository base, polyethylene glycol (PEG) 1000, at 50 degreesC, and was hardened in the capsular shape the sizes of which were #0 and #2. The capsular shaped suppositories were coated with 5% w/v ethanolic EC (7G grade) solution by a coating machine. By increasing the coating time from 55 to 75 min, the mean coating thickness of #0 PCDCs increased from 141+/-7 to 211+/-4 micrometer. In the case of #2 PDDCs, the mean coating thickness increased from 102+/-3 to 110+/-5 micrometer by increasing the coating time from 35 min to 40 min. Several kinds of #0 PCDCs having the mean EC coating membrane thickness of 141+/-7 micrometer (type 1), 166+/-4 micrometer (type 2), 188+/-4 micrometer (type 3), 211+/-4 micrometer (type 4) as well as #2 PCDCs having thickness of 102+/-3 micrometer (type 5) and 110+/-5 micrometer (type 6) were used for in vivo evaluation using beagle dogs. After oral administration of the test preparations containing 30 mg of FL, blood samples were obtained from the jugular vein and plasma FL levels were measured. The first appearance time, Ti, of FL in the plasma was used as a parameter for the estimation of the release time of FL from PCDCs in the gastrointestinal tract. The mean Ti of #0 PCDCs were 2.3+/-0.5 for type 1, 3.3+/-0.5 for type 2, 4.8+/-1.0 for type 3 and 7.8+/-1.7 h for type 4 preparations while the mean Ti of #2 PCDCs were 3.2+/-0.4 for type 5 and 3.8+/-0.4 h for type 6, respectively. There were good correlations between EC coatings.

Animals↗
PubMed1998

In vivo effects of pioglitazone on uncoupling protein-2 and -3 mRNA levels in skeletal muscle of hyperglycemic KK mice.

Pioglitazone is a thiazolidinedione drug (TZD) which potently and specifically stimulates peroxisome proliferator-activated receptor gamma (PPAR gamma) and sensitizes cells to insulin. Since TZDs are thought to increase energy expenditure, changes in mitochondrial thermogenesis uncoupling protein-2 and -3 mRNA levels in response to pioglitazone treatment were measured in mouse skeletal muscle. Normally hyperglycemic and hyperinsulinemic KK/Ta mice were given pioglitazone for 2 weeks to treat this non-insulin dependent diabetes-like condition. During treatment, UCP2 mRNA levels increased to 185% of normal untreated control levels in soleus muscle. In contrast, UCP3 mRNA levels significantly decreased, up to 67% of normal untreated control levels. Interestingly, UCP3 mRNA levels correlated quite strongly with blood glucose levels, with r = 0.82 for gastrocnemius tissue and r = 0.92 for soleus tissue. These results may indicate that pioglitazone increases glucose catabolism by direct upregulation of muscle UCP2 gene expression in vivo. Therefore, UCP3 gene expression is controlled by a different mechanism than UCP2 expression.

Animals↗
PubMed1998

Transcriptional regulation of muscle-specific genes during myoblast differentiation.

A rapid, highly sensitive method to determine the mRNA level of muscle-specific markers using TaqMan PCR analysis was developed and used to study sequential gene regulation of myoblasts during induced differentiation of C2C12 cells. mRNA levels of muscle regulatory factor (MRF) myogenin, alpha-actin, thermoregulatory uncoupling protein UCP2 and glucose transporter isotype glut4 increased rapidly during early stage differentiation. In contrast, myf5, beta-actin, UCP1 and glut1 mRNA levels gradually decreased during 8 days. However, the mRNA level of other genes such as MyoD, glyceraldehyde-3-phosphate dehydrogenase and hexokinase II changed only slightly in comparison. Muscle-specific uncoupling protein UCP3 mRNA was detected during differentiation and increased rapidly within 8 days. These data clearly show the sequential and the differential regulation of muscle-specific genes in C2C12 cells during multinucleate myotube formation.

Animals↗
PubMed1998

Evaluation of intestinal pressure-controlled colon delivery capsule containing caffeine as a model drug in human volunteers.

The delivery ability of a pressure-controlled colon delivery capsule (PCDC) containing caffeine as a test drug was evaluated after oral administration to healthy male human volunteers. The driving force causing PCDC disintegration in the intestinal tract is the physiological luminal pressure which results from peristalsis. Three kinds of PCDCs having different thickness of a water-insoluble polymer membrane was prepared by coating the inner surface of the gelatin capsules with ethylcellulose (EC). The mean thickness were 40 +/- 1 (SE) for type 1, 44 +/- 1 for type 2 and 50 +/- 1 micron for type 3 PCDC, respectively. Caffeine was dissolved with a suppository base (PEGs 400 and 1000) and the capsules were filled. Doses were 15, 45 or 75 mg. After blank saliva samples were obtained, test preparations were orally administered to the volunteers and saliva samples were collected for 1 min intervals hourly from 1 to 10 h in the fasted state study, and from 1 to 20 h and at 25 h in the fed state study. Caffeine concentrations in the saliva samples were analyzed by HPLC. The maximum salivary caffeine excretion rate increased as the oral caffeine dose increased. The maximum salivary caffeine excretion rate increased predominantly compared to the pre-dose level in 75 mg dose study. Therefore, all following studies were performed with this dose. The first appearance time of caffeine into the saliva, TI, was used as a parameter to estimate the disintegration time of test preparations in the gastrointestinal tract. The mean TI of types 1, 2, and 3 PCDCs were 3.0 +/- 0.4, 4.0 +/- 0.4 and 4.5 +/- 0.3 h, respectively. After oral administration of 75 mg caffeine in pain gelatin capsule as a reference preparation, caffeine appeared in the saliva within 0.5 h. The mean hardness of the PCDCs were 1.05 +/- 0.10 (type 1), 1.55 +/- 0.06 (type 2) and 2.08 +/- 0.15 newton (type 3), respectively. There were good correlations between three parameters: EC coating membrane thickness, hardness and TI (determination coefficient r2 = 0.935 between TI and thickness, r2 = 0.998 between thickness and hardness, r2 = 0.958 between hardness and TI). The effect of food intake on the delivery ability was examined with type 3 PCDCs. Food intake prolonged the mean TI, from 4.5 +/- 0.3 to 7.8 +/- 1.3 h. This increase is thought to be ascribed to prolonged gastric emptying time. Comparison with reported colon arrival times indicates that the type 3 PCDC functions in colon delivery of caffeine and is thought to be applicable to other drugs.

Adult↗
PubMed1998

Innervation analysis of the small muscle bundles attached to the temporalis: truly new muscles or merely derivatives of the temporalis?

Detailed examinations were performed in ten temporal muscles from five cadavers to identify the muscle bundle arrangements of the temporalis and their innervation. Three additional muscle bundles were clearly observed in the main part of the fan-shaped temporalis: the anteromedial, anterolateral, and mid-lateral muscle bundles. Based on the origins, insertions and detailed innervation patterns, these bundles were considered as parts of the temporalis rather than independent muscles, although the anteromedial and anterolateral bundles had been recently reported as newly described muscles. A possible schematic model of the origins of these muscle bundles is proposed. We also report a branch from the posterior deep temporal nerve which was distributed to the temporal fascia and to the skin of the temporal region.

Cadaver↗
PubMed1998

[The effect of intraoperative high-dose tranexamic acid on blood loss after operation for acute aortic dissection].

The effect of high dose tranexamic acid on blood loss after operations for acute aortic dissection was evaluated. Twenty-eight patients undergoing emergent operations for acute aortic dissection were studied. There were two groups, group T with 13 patients (group T) who were given 7 g of tranexamic acid after induction of anesthesia and 3 g of it after CPB and group C with 15 patients who did not receive tranexamic acid. There was a tendency that group T had less bleeding during operation and after operation (559.6 +/- 865.8 ml in group T and 805.8 +/- 442.9 ml in group C, 1719.2 +/- 1008.7 ml in group T and 3547.7 +/- 4580.1 ml in group C, respectively), but there was no significant difference between two groups. The removal of drainage tubes after operation was significantly earlier in group T (5.0 +/- 2.3 post operative day in group T and 8.1 +/- 5.2 post operative day in group C; p < 0.05). FDP and D-dimer level as measures of fibrinolytic activity were elevated at pre- and postoperative period in both groups, but they tended to be lower in group T at postoperative period. One patient required reexploration because of excessive bleeding and no mediastinal infection was reported in group T, whereas 4 patients underwent reexploration and 2 patients developed mediastinitis in group C. There were 5 hospital death (33.3%) in group C and 2 (15.4%) in group T. High dose of tranexamic acid seems to control fibrinolytic activity, thereby reducing blood loss and requirements, which may contribute to lower morbidity and mortality in operations for acute aortic dissection.

Acute Disease↗
PubMed1998

Peripheral blood stem cell autografts for the treatment of children over 1 year old with stage IV neuroblastoma: a long-term follow-up.

This is the first report of the long-term therapeutic results in 22 children more than 1 year old with stage IV neuroblastoma who were treated with autologous peripheral blood stem cell transplantation (PBSCT). The median age of the patients at PBSCT was 4 years (1 to 10 years) and seven of the 17 patients who were evaluated for N-myc amplification were positive. PBSC were collected by a median of four aphereses per patient. The patients underwent PBSCT from 6 to 21 months after the start of therapy (median 10.5 months) at which time 13 patients were in CR, seven were in PR, and two had refractory disease. Multi-drug therapy using the 'high-MEC' regimen consisting of carboplatinum (400 mg/m2) and VP-16 (200 mg/m2) on days -7 to -4, and melphalan (90 mg/m2) on days -3 and -2, was the primary cytoreductive regimen. The median number of infused MNC and CFU-GM was, respectively, 4.3 x 10(8)/kg and 2.4 x 10(5)/kg. After PBSCT, three patients died of regimen-related toxicities and one patient who was transplanted with refractory disease died of disease progression without any benefit from transplantation. Hematological recovery was evaluated in 21 patients, excluding one early death. The median number of days required to achieve an AGC of >0.5 x 10(9)/l and platelet count of >50 x 10(9)/l were, respectively, 11 and 46. Eleven patients relapsed 3 to 50 months after PBSCT, and currently seven patients (5/13 who were transplanted in CR and 2/7 in PR) are surviving disease-free at 52 to 84 months. Although the retrospective nature of this study and several variables prevent a meaningful analysis, the overall results still support the feasibility of developing a prospective study of PBSCT with a larger number of children with high-risk neuroblastoma.

Child↗
PubMed1998

Physical mapping of duplicated genomic regions of two chromosome ends in rice.

Two genomic regions duplicated in distal ends of the short arms of chromosomes 11 and 12 in rice (Oryza sativa L.) were characterized by YAC ordering with 46 genetic markers. Physical maps covering most of the duplicated regions were generated. Thirty-five markers, including 21 rice cDNA clones, showed the duplicated loci arrayed strictly in the same order along the two specific genomic regions. Regardless of their different genetic distances, the two duplicated segments may have a similar and minimum physical size with an expected length of about 2.5 Mb. However, differences of RFLP frequency for the duplicated DNA copies and recombination frequency for a given homoeologous area between the two regions were observed, indicating that these changes in genome organization occurred after the duplication. Our results establish a good model system for resolving the relationships between gene duplication, expression of duplicated genes, and the frequency of meiotic recombination in small chromosomal regions.

Chromosomes, Artificial, Yeast↗
PubMed1998

Hypocholesterolemic effects of the LDL receptor gene transcriptional upregulator CP-230821.

CP-230821 is a novel, potent LDL receptor gene transcriptional upregulator which decreases total plasma cholesterol level. Interestingly, this plasma LDL decrease does not alter hepatic lipid contents. A series of experiments was undertaken to study the molecular biology of this phenomenon. Twelve hours after CP-230821 treatment, the transcriptional activity and mRNA level of the LDL receptor gene in HepG2 cells were increased by 264% and 426%, respectively. Although treatment with the HMG-CoA reductase inhibitor compactin also increased LDL receptor gene transcription and mRNA, CP-230821 did not increase the level of HMG-CoA reductase gene transcription or mRNA. These results indicate that LDL receptor gene activity may play an important role in the decrease of plasma LDL level. These results further suggest that the LDL receptor gene and the HMG-CoA reductase gene are not strictly coordinately controlled.

Animals↗
PubMed1998

The human poly(ADP-ribose) glycohydrolase maps to chromosome 10q11.23-21.1 by fluorescence in situ hybridization.

Poly(ADP-ribose) glycohydrolase (PARG) digests poly(ADP-ribose), which is synthesized by poly(ADP-ribose) polymerase (PARP) after DNA damage. We mapped the human poly(ADP-ribose) glycohydrolase gene to chromosome 10q11.23-21.1 by fluorescence in situ hybridization analysis. Since chromosomal rearrangements in thyroid papillary carcinoma and loss of heterozygosity in glioblastoma are frequently observed in this region, genetic alteration of PARG could be implicated in these diseases.

Base Sequence↗