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Biomedical subjects

H Taniguchi

Publications and source records attributed to H Taniguchi.

At least 235 records · Page 13Linked to original sources
PubMed1997

Specific binding of acidic phospholipids to microtubule-associated protein MAP1B regulates its interaction with tubulin.

Microtubule-associated protein MAP1B, a major neuronal cytoskeletal protein, is expressed highly during the early stage of brain development and is thought to play an important role in brain development. Although it has been shown that MAP1B localizes both in cytosol and particulate fractions, the underlying molecular mechanism in the membrane localization has yet to be elucidated. In the present study, we show that MAP1B purified from young rat brain can bind to acidic phospholipids, such as phosphatidylserine, but not to a neutral phospholipid, phosphatidylcholine. Furthermore, the binding of MAP1B to taxol-stabilized microtubules was inhibited by the addition of phosphatidylserine or phosphatidylinositol. The addition of phosphatidylcholine showed no effect on the binding of MAP1B to the microtubules. A 120-kDa microtubule-binding fragment of MAP1B was also released from microtubules by the addition of acidic phospholipids. Synthetic peptides derived from the C-terminal half of the tubulin-binding domain, but not that corresponding to the N-terminal half, bound to acidic phospholipids specifically. These results suggest that MAP1B binds to biological membranes through its tubulin-binding site, and the binding may play a regulatory role in MAP1B-microtubule interaction.

Amino Acid Sequence↗
PubMed1997

Structural and functional domains of the troponin complex revealed by limited digestion.

Troponin (Tn), consisting of three subunits, TnT, TnC, and TnI, plays a crucial role in the calcium-dependent regulation of vertebrate striated muscle contraction. In the present study, we have applied limited proteolysis to the Tn complex in order to study domain structures and to detect conformational differences of Tn under different conditions. We found that both TnT and TnI were susceptible to chymotryptic digestion: while TnT was cleaved into TnT-(1-158)-peptide and TnT-(159-259)-peptide irrespective of Ca2+ concentration, the cleavage sites of TnI were dependent on the Ca2+ occupancy of TnC. In addition, we characterized the effects of depletion of the C-terminal part of TnI on acto-S1 ATPase activity. The TnT-(159-259)-peptide-TnC-TnICa-frag complex [TnICa-frag = (TnI-(1-134 and 1-140)-peptide], which was produced in the presence of CaCl2 and MgCl2, retains both the activating and inhibitory capabilities of whole Tn on the acto-S1 ATPase activity, while TnT-(159-259)-peptide-TnC-TnIMg-frag complex [TnIMg-frag = (TnI-(1-116)-peptide], which was obtained in the presence of MgCl2 and EGTA, lost its ability to activate acto-S1 ATPase activity. Our results indicate that residues 117-134 or 117-140 of TnI undergo structural changes upon Ca(2+)-binding to the regulatory sites of TnC and are necessary for the Ca(2+)-dependent inhibitory action of the Tn complex on acto-S1 ATPase activity. We also showed that residues 135-181 or 141-181 of TnI are involved in the interaction of Tn with the tropomyosin-actin filament.

Animals↗
PubMed1997

Specific proteolytic cleavage of the myristoylated alanine-rich C kinase substrate between Asn 147 and Glu 148 also occurs in brain.

The myristoylated alanine-rich C kinase substrate (MARCKS) is a major ubiquitous substrate of protein kinase C. The expression of the protein is regulated during cell cycle progression and cell proliferation. Specific proteolytic cleavage of the protein between Asn 147 and Glu 148 was described recently in cultured cells, and the corresponding proteolytic activity was observed in various tissue extracts except for brain. We purified a 40 kDa fragment of MARCKS from bovine brain that we characterized as the C-terminal specific fragment found in other tissues. The identification of the fragment was achieved by in vitro phosphorylation by protein kinase C, calcium-dependent interaction with calmodulin, mass spectrometric analysis, and N-terminal sequencing. These data suggest that specific proteolytic cleavage of MARCKS also occurs in brain and may be a general mechanism of down-regulation of the protein.

Amino Acid Sequence↗
PubMed1997

Circular dichroism and 1H nuclear magnetic resonance studies on the solution and membrane structures of GAP-43 calmodulin-binding domain.

Growth-associated protein-43 (GAP-43) is believed to be palmitoylated near the N terminus and the modification is assumed to be involved in the membrane anchoring of the protein. However, GAP-43 isolated from bovine brain is not palmitoylated as shown by mass spectrometric analysis, but still retains the ability to bind phospholipids, suggesting that other parts of the molecule are involved in the interaction. Upon addition of acidic phospholipids, purified GAP-43 showed a conformational change from random coil to alpha-helix as indicated by a change in CD spectra. A synthetic peptide corresponding to the calmodulin-binding domain showed a similar conformational change from random coil to alpha-helix in the presence of various acidic phospholipids. These results suggest that the calmodulin-binding domain of GAP-43 is directly involved in the GAP-43-membrane interaction and undergoes a conformational change upon binding to phospholipid membranes. After phosphorylation by protein kinase C, the phospholipid-induced conformational changes were no longer observed. Structural characteristics of the calmodulin-binding domain peptide in aqueous and hydrophobic solvents were further studied in detail by two-dimensional 1H nuclear magnetic resonance. The results obtained suggest that the domain assumes a nascent alpha-helical structure in aqueous solution, which is stabilized under hydrophobic environments.

Animals↗
PubMed1997

Hepatic allograft procurement from non-heart-beating donors: limits of warm ischemia in porcine liver transplantation.

To investigate the tolerance to warm ischemia of liver grafts from non-heart-beating donors, porcine orthotopic liver transplantation was performed using grafts obtained at various periods after cardiac arrest. Graft viability was investigated in relation to changes in hepatic adenine nucleotide metabolism. In donors, livers were divided into four groups according to warm ischemic time after cardiac arrest (group 1: 0 min, n=3; group 2: 30 min, n=3; group 3: 60 min, n=5; group 4: 90 min, n=4). Thereafter, the livers were flushed and preserved for 4 hr using 4 degrees C Euro-Collins solution. After surgery, all of the recipients in groups 1, 2, and 3 survived more than 4 days, except for one pig in group 3 that died of bleeding from an arterial catheter on day 2. By contrast, all of the recipients in group 4 died within 12 hr. The serum glutamic oxaloacetic transaminase concentration at 4 hr after reperfusion of the graft was significantly higher in group 4 (mean+/-SE, 2563+/-556 IU/L) than in groups 1, 2, and 3 (298+/-29 IU/L, 1226+/-222 IU/L, and 1181+/-174 IU/L, respectively). The adenylate energy charge of the liver graft recovered at 1 hr after reperfusion of the graft to 0.852+/-0.013, 0.845+/-0.003, and 0.842+/-0.003 in groups 1, 2, and 3, respectively. The recovery was significantly suppressed in group 4 (0.796+/-0.011). The hepatic adenosine triphosphate concentration also was significantly lower in group 4 compared with the other groups. The present study suggests that liver allografts can be used from non-heart-beating donors subjected to warm ischemia for less than 60 min. Postoperative survival is associated with prompt recovery of the adenylate energy charge of the liver graft.

Adenine Nucleotides↗
PubMed1997

Analysis of lymph node metastasis in early gastric cancer: rationale of limited surgery.

BACKGROUND: Since the majority of patients with early gastric cancer show long-term survival after surgery, a special attention must be directed to preserving gastric function in these patients. Little is known about the protocol of surgical treatment appropriate for early gastric cancer patients. This study was designed to determine the appropriate surgical procedure for early gastric cancer. METHODS: The clinicopathologic features of 52 patients with node-positive early gastric cancer were reviewed retrospectively from hospital records between 1969 and 1994 and were compared with those of 582 patients with node-negative early gastric cancer. Nodal status of positive nodes in the 52 cases was investigated. RESULTS: Depth of invasion, lymph vessel invasion, and tumor size were associated with lymph mode metastasis. Node-positive patients with early gastric cancer had a poorer survival rate than node-negative patients (P < 0.05). Patients with five or more positive nodes and positive nodes distant from the common hepatic artery showed an extremely poor prognosis. CONCLUSIONS: The surgical procedures most appropriate for the treatment of early gastric cancer are as follows: (1) local gastric resection without lymphadenectomy for mucosal cancers of < 2 cm in diameter and for elevated submucosal cancers of < 1 cm in diameter, (2) gastrectomy with dissection of the perigastric nodes, the nodes along the left gastric artery and the common hepatic artery, for the treatment of other early gastric cancers.

Aged↗
PubMed1997

Production, crystallization, and preliminary X-ray analysis of rabbit skeletal muscle troponin complex consisting of troponin C and fragment (1-47) of troponin I.

Troponin is a ternary protein complex consisting of subunits TnC. TnI, and TnT, and plays a key role in calcium regulation of the skeletal and cardiac muscle contraction. In the present study, a partial complex (CI47) was prepared from Escherichia coli-expressed rabbit skeletal muscle TnC and fragment 1-47 of TnI, which is obtained by chemical cleavage of an E. coli-expressed mutant of rabbit skeletal muscle TnI. Within the ternary troponin complex, CI47 is thought to form a core that is resistant to proteolytic digestion, and the interaction within CI47 likely maintains the integrity of the troponin complex. Complex CI47 was crystallized in the presence of sodium citrate. The addition of trehalose improved the diffraction pattern of the crystals substantially. The crystal lattice belongs to the space group P3(1)(2)21, with unit cell dimensions a = b = 48.2 A, c = 162 A. The asymmetric unit presumably contains one CI47 complex. Soaking with p-chloromercuribenzenesulfonate (PCMBS) resulted in loss of isomorphism, but enhanced the quality of the crystals. The crystals diffracted up to 2.3 A resolution, with completeness of 91% and R(merge) = 6.4%. The crystals of PCMBS-derivative should be suitable for X-ray studies using the multiple-wavelength anomalous diffraction technique. This is the first step for elucidating the structure of the full troponin complex.

Animals↗
PubMed1997

Constant delivery of proinsulin by encapsulation of transfected cells.

Gene therapy is a potentially excellent approach for the treatment of diabetes instead of pancreas and islet transplantation. However, one difficulty involved in gene therapy for diabetes is a control of insulin/proinsulin production by the cells transfected with insulin cDNA. The purpose of this study is to examine whether control of the proliferation of transfected cells by encapsulation is a feasible approach for the constant delivery of proinsulin to avoid a life-threatening hypoglycemic state. Previously, we established a mouse fibroblast Ltk- cells transfected with human insulin cDNA producing human proinsulin (91 ng/24 hr/10(6) cells). These cells were encapsulated with semipermeable 5% agarose gel and proinsulin production was examined by in vitro long-term culture system. Intraperitoneal implantation into streptozocin (STZ)-induced diabetic mice was performed to investigate in vivo function of the encapsulated cells. The data from the in vitro study demonstrated that encapsulation of 2 x 10(6) transfectants enabled the stable production of proinsulin for over 80 days (204.4 +/- 5.18 ng/ml/day). Implantation of the encapsulated 2 x 10(7) transfectants improved the hyperglycemic state of diabetic mice for 30 days on the mean value of blood glucose concentration (n = 20). Histological analysis revealed pericapsular inflammation at 30 days after implantation and this may result in malfunction of encapsulated cells. Constant production and delivery of proinsulin could be achieved by encapsulating the human insulin cDNA-transfected cells using 5% agarose. Control of the proliferation of transfected cells appears to be an important factor for constant delivery of human proinsulin toward gene therapy of diabetes mellitus.

Animals↗
PubMed1997

Increased apoptosis rate by hyperthermochemoradiotherapy for advanced rectal cancers.

Apoptosis induced in cancer cells by ionizing radiation, hyperthermia, and 5-fluorouracil (5-FU), termed "hyperthermochemoradiotherapy" (HCR), has been well studied in vitro; however, the role of apoptosis in the tumocidal effect of HCR for primary rectal cancers has not yet been clarified. Therefore, we examined the relationship between the therapeutic effect and induction rate of histological apoptosis in 16 patients with rectal cancers after HCR. Numerous Tunel-positive apoptotic cells were found in the tumor tissue after HCR, but few were found in the tumors which had not received HCR. The histological therapeutic effect was closely correlated to the rate of apoptosis. Thus, we suggest that HCR induces a therapeutic effect mainly through apoptosis in human rectal cancers.

Administration, Rectal↗
PubMed1997

The operative indications for proximal gastrectomy in patients with gastric cancer in the upper third of the stomach.

While proximal gastrectomy is often performed for early gastric cancer in Japan, it remains unclear whether or not proximal gastrectomy should be performed for advanced gastric cancer. This study was designed to determine the operative indications for proximal gastrectomy in patients with gastric cancer in the upper third of the stomach. A total of 1691 patients with gastric cancer were reviewed retrospectively from hospital records during the period from 1969 to 1994, and the clinicopathologic characteristics of 82 patients who underwent proximal gastrectomy were compared with those of 150 patients who underwent total gastrectomy. Lymph node metastasis along the lower part of the stomach was observed in gastric cancers which had invaded beyond the muscularis propria of the stomach, but not in those confined to the muscularis propria. Three patients with gastric cancer that had invaded beyond the muscularis propria and metastasized to nodes along the lower part of the stomach were cured by total gastrectomy. However, there was no difference in the postoperative survival rates of the patients treated with proximal gastrectomy and those treated with total gastrectomy, irrespective of tumor stage and depth of invasion. Thus, proximal gastrectomy should be performed for gastric cancer when the depth of invasion is confined to the muscularis propria of the stomach.

Aged↗
PubMed1997

Analysis of vascular anatomy and lymph node metastases warrants radical segmental bowel resection for colon cancer.

To determine the indications for limited colon cancer surgery in each location, we reviewed the arterial branching patterns and lymph node metastases along the course of specific vascular trunks in 344 colon cancer patients who had undergone preoperative angiography and colectomy with lymph node dissection. Our conclusions are follows: Because the ileocecal artery always arises from the superior mesenteric artery and lymph node metastases of cecum cancer were limited to nodes along the ileocolic artery, cecum cancer can be cured by ileocecal resection. The right colic artery has various origins, and ascending colon cancer shows various patterns of lymph node metastases. Therefore a right hemicolectomy should be performed for ascending colon cancer. The middle colic artery forks into right and left branches, and each branch has different branching variations. If the right colic and middle colic arteries have a common trunk, a right hemicolectomy should be performed for transverse colon cancer on the right side. If the left branch of the middle colic artery has an independent replaced origin, lymph node dissection should be modified according to the variant origin. If the left colic artery and the first sigmoidal artery have a common trunk, the lymph nodes along the common trunk should be removed for sigmoid colon cancer and for descending colon cancer. Of the patients with sigmoid colon cancer, 6.3% also had lymph node metastases along the superior rectal artery. Given that the lymph nodes along the superior rectal artery are skeletonized, sigmoid colon cancer can be also cured by partial sigmoidectomy.

Arteries↗
PubMed1997

Evaluation of non-steroidal ointment therapy for adult type atopic dermatitis: inquiry analysis on clinical effect.

Clinical analysis was performed on non-steroidal ointment therapy for 70 patients with refractory adult-type atopic dermatitis by the clinical data and patient's own evaluation of the therapy obtained through enquiries after discharge from the hospital. Forty cases (57%) were between 20 and 30 years old and the male and female ratio was 39/31. The clinical evaluations were subdivided into five groups; conditions worsened (n = 9), no-change (n = 9), slightly improved (n = 14), much improved (n = 29) and cured (n = 9). Although statistically not significant, the age of onset of atopic dermatitis and the start of use of steroid ointment was much higher while the duration of the atopic dermatitis was much shorter in the remission patients. The duration of steroid ointment therapy for the facial skin was significantly shorter in the remission group when compared to groups with worsened symptoms and no-change in symptoms. Family history and complications of atopic diseases, laboratory data including IgE titer, eosinophils and RAST score were not statistically significant in any group except for a higher prevalence of IgE antibodies against inhalant and food allergens in the group with worsened symptoms. Most patients still used steroid ointment on the trunk lesions while they ceased using from the topical steroid on the facial lesions after discharge. Most frequent precipitating factors pointed out by the patients were emotional stress, irritation by sweat or UV light and longstanding use of steroid ointment. Complications of cataracta and retinopathy were found in 12 cases. These results suggest that remission of adult-type refractory atopic dermatitis can be achieved by the combination of careful daily skin care, use of non-steroidal topical ointment and minimizing the precipitating factors.

Adolescent↗
PubMed1997

Early gastric cancer mimicking advanced gastric cancer.

The clinicopathological features of 37 early gastric cancers mimicking advanced gastric cancer were reviewed retrospectively, and were compared with 596 other early gastric cancers and 126 mp gastric cancers, defined as gastric cancer invading the muscularis propria of the stomach. A greater tumour size (P < 0.005), submucosal invasion (P < 0.005), lymph node and lymph vessel invasion (P < 0.005) and vascular invasion (P < 0.025) were found more frequently in early gastric cancers mimicking advanced gastric cancers than in other early gastric cancers. There were no significant differences in the clinicopathological findings between early gastric cancers mimicking advanced gastric cancers and mp gastric cancers. Patients with early gastric cancers mimicking advanced gastric cancers showed a lower survival rate than patients with other early gastric cancers, but a higher survival than those with mp gastric cancers. The macroscopic appearance of an advanced gastric cancer was an indicator of massive submucosal invasion and lymph node metastasis in early gastric cancer. As early gastric cancers mimicking advanced gastric cancers showed similar clinicopathological findings to mp gastric cancers, these cancers should be treated as mp gastric cancers.

Female↗
PubMed1997

Stability of the mandibular position in occlusion of mandibulectomy patients with lateral discontinuity defect.

In mandibulectomy patients with lateral discontinuity defect, the mandible is severely deviated and the occlusion is considered to be unstable. A thorough understanding of the mandibular occlusal position of these patients is important to achieve desirable results in their occlusal rehabilitation. This study compared the stability of the mandibular positions in occlusion, when the opening distance or the biting force was changed during mandibular movements, by simultaneously measuring four points on the mandible three-dimensionally. This study indicated that the mandibular positions in occlusion of these patients were extremely unstable as compared with those of the normal subjects and were considerably different from each other when the opening distance or the biting force was changed during mandibular movements.

Bite Force↗
PubMed1997

Molecular analysis of kanamycin and viomycin resistance in Mycobacterium smegmatis by use of the conjugation system.

We examined the molecular mechanisms of resistance to kanamycin and viomycin in Mycobacterium smegmatis. All of the M. smegmatis strains with high-level kanamycin resistance had a nucleotide substitution from A to G at position 1389 of the 16S rRNA gene (rrs). This position is equivalent to position 1408 of Escherichia coli, and mutation at this position is known to cause aminoglycoside resistance. Mutations from G to A or G to T at position 1473 of the M. smegmatis rrs gene were found in viomycin-resistant mutants which had been designated vicB mutants in our earlier studies. Using the M. smegmatis conjugation system, we confirmed that these mutations indeed contributed to kanamycin and viomycin resistance, and kanamycin susceptibility was dominant over resistance in a heterogenomic strain. Additional experiments showed that three of four Mycobacterium tuberculosis strains with high-level kanamycin resistance had a mutation from A to G at position 1400, which was equivalent to position 1389 of M. smegmatis.

Base Sequence↗
PubMed1997

Higher concentrations of matrix metalloproteinases in bronchoalveolar lavage fluid of patients with adult respiratory distress syndrome.

This study was designed to investigate possible involvement of type IV collagenolytic matrix metalloproteinases (MMPs; 72-kDa type IV collagenase [MMP-2], 92-kDa type IV collagenase [MMP-9]), and the respective specific tissue inhibitors of these MMPs (TIMP-2 and TIMP-1) in the development of adult respiratory distress syndrome (ARDS). We determined the concentrations of these enzymes in the bronchoalveolar lavage fluid (BALF) from patients with ARDS using newly developed sensitive one-step sandwich enzyme immunoassay methods. BALF obtained from the 17 patients and eight healthy volunteer control subjects were also used for the analysis of the number of the cellular component. Concentrations of the 7S portion of type IV collagen and laminin in the BALF were measured as markers of basement membrane disruption. In the BALF from the ARDS patients, the concentrations of MMP-2 (66.7 +/- 57.0 ng/ml versus < 7.0 ng/ml for controls, p < 0.01) and MMP-9 (118.0 +/- 309.3 ng/ml versus 9.0 +/- 9.5 ng/ml for controls, p < 0.05), and the specific inhibitor of MMP-9 (TIMP-1) (161.0 +/- 145.0 ng/ml versus < 50 ng/ml for controls, p < 0.01) were significantly higher compared with those for healthy control subjects. In the ARDS patients, the concentrations of MMP-2 correlated both with those of 7S collagen and laminin; MMP-9 with the concentration of 7S collagen and the number of neutrophils. These findings suggest that the increased concentration of collagenolytic MMPs in lung plays a role in the pathogenesis of ARDS.

Adult↗