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Biomedical subjects

T Ohyama

Publications and source records attributed to T Ohyama.

At least 145 records · Page 8Linked to original sources
PubMed1997

Prosthodontic treatment for patients with large mandibular defects; porous hydroxyapatite grafts.

It is difficult for both prosthodontists and their patients with large marginal defects to achieve a satisfactory prosthodontic result, because retention, support, and stability of the prosthesis are limited and recovery of esthetics is unsatisfactory owing to large mandibular defects. Alveolar ridge augmentation therapy is performed to compensate for such problems. We have experienced a good prognosis of prosthodontic treatment for over 10 years in two patients with large marginal defects of the partially edentulous mandible, who had undergone grafting of porous hydroxyapatite blocks to their bone defects. It has been reported that porous hydroxyapatite blocks are unsuitable for edentulous patients, because the mucosa covering the hydroxyapatite block is too thin and delicate to support dentures. We, therefore, designed the denture to prevent concentration of occlusal stress on the mucosa. In both of these two cases, we achieved recovery of occlusal function and esthetics by affixing denture to the large marginally resected defect augmented with a graft of porous hydroxyapatite block.

Adult↗
PubMed1997

Deoxyribonuclease secreted from an insectivorous plant Drosera adelae.

A deoxyribonuclease that is secreted from an insectivorous plant Drosera adelae was partially purified by column chromatography. The enzyme acted as an endonuclease on double-stranded DNA and generated oligonucleotides with 3' hydroxyl and 5' phosphate ends. The activity of the enzyme was high in the range from pH 3.5 to 5.0. The enzyme seemed to require divalent cations for maximum activity.

Animals↗
PubMed1996

Methotrexate bound to carbon particles used for treating cancers with lymph node metastases in animal experiments and a clinical pilot study.

BACKGROUND: A new dosage formulation, methotrexate adsorbed onto activated carbon particles (MTX-CH), was developed for treating cancer patients with lymph node metastases. METHODS: MTX-CH injected subcutaneously into the left hind foot pad of rats delivered greater amounts of methotrexate selectively to the regional lymph nodes and to the injection site for longer periods than did the same dose of methotrexate in aqueous solution. Seven days after mice received a subcutaneous inoculation with 5 x 10(5) P388 leukemia cells in the left hind foot pad, when metastasis had occurred in the left popliteal lymph node, methotrexate was injected subcutaneously into the left hind foot pad in the form of either MTX-CH or methotrexate aqueous solution. In clinical trials, patients with cancers in relatively early stages (5 patients with gastric cancer and 1 with esophageal cancer) each received local injections of MTX-CH doses of 250 to 500 mg under fiberscope. RESULTS: MTX-CH extended the survival time better than did methotrexate aqueous solution. In mice who received an inoculation of P388 leukemia cells and drug treatment using the same procedures, the treatment effects on metastases to the regional lymph nodes were significantly greater in mice treated with the MTX-CH than in those given methotrexate aqueous solution. MTX-CH controlled the disease well for 25 to 35 months. CONCLUSIONS: Local injection of MTX-CH is apparently useful for treating digestive cancers with lymph node metastases in patients who have difficulty tolerating surgery.

Aged↗
PubMed1996

Bent DNA in the human adenovirus type 2 E1A enhancer is an architectural element for transcription stimulation.

The upstream half of the human adenovirus type 2 enhancer adopts a curved DNA structure. Most of the enhancer elements are within the curvature, suggesting that this unusual structure is linked to enhancer function. To verify this experimentally, I constructed in vitro transcription assay systems which could distinguish any effects generated by conformational changes in a DNA template. The curved DNA conformation in the enhancer clearly affected the extent of the stimulation of the E1A gene transcription: assays using the wild-type DNA template showed that the moderately curved enhancer was superior to the highly curved enhancer in transcriptional stimulation. In additional experiments, the enhancer region was substituted with a curved DNA derived from the bacteriophage lambda origin of replication. Assays using this mutant revealed that this curved segment could also act as an enhancer when it had the proper conformation. Consequently, DNA conformation may play a general role in transcriptional stimulation.

Adenovirus E1A Proteins↗
PubMed1996

Overexpression of bax sensitizes human breast cancer MCF-7 cells to radiation-induced apoptosis.

Resistance to apoptosis plays an important role in tumors that are refractory to chemotherapy and ionizing radiation (IR). bax, which forms a heterodimer with bcl-2 and accelerates apoptosis, is not, or only weakly, expressed in most human breast cancer cells, and weak bax expression is considered to be related to the resistance of breast cancer cells to apoptosis. bax expression vector was introduced to human breast cancer MCF-7 cells, which exhibit weak expression of bax, to demonstrate its role of modulating radiation-induced apoptosis. bax overexpression in MCF-7 cells by stable transfection does not affect viability by itself, but each stable transfectant was more sensitive to IR than the parental MCF-7 cells. The degree of enhancement in radiosensitivity was dependent on the expression level of bax. IR upregulated p53 and p21WAF1 about 5- to 10-fold and downregulated bcl-2 and bcl-XL by 80-90% at 6 hr in both parent and bax stably transfected MCF-7 cells to the same degree. FACS analysis and DNA electrophoresis revealed that this sensitization was due to apoptosis. We suggest that exogenous bax expression might be one of the factors determining cellular radiosensitivity in MCF-7 breast cancer cells and may have therapeutic applications for enhancing radiation sensitivity in breast cancer cells.

Apoptosis↗
PubMed1996

Visualization of yellowish-orange luminescence from cuprous metallothioneins in liver of Long-Evans Cinnamon rat.

We describe the first use of an emission probe, based on the cuprous thiolate chromophore, for direct microscopical observation of cuprous metallothioneins located in liver of 15-week-old (just before spontaneous hepatitis) Long-Evans Cinnamon rats. The rats show remarkable accumulations of copper and cuprous metallothioneins. In the mildly fixed liver, we visualized the same yellowish-orange luminescence as the specific emission from cuprous metallothioneins, following excitation in 330-385 nm region. In liver from Long-Evans Agouti rat, a counter part of Long-Evans Cinnamon rat, no similar luminescence was found. So, it was thought that cuprous metallothioneins accumulated in the Long-Evans Cinnamon rat liver might emit the yellowish-orange light. To verify this presumption, we tentatively defined three histochemical criteria, quenching tests by oxidation, protonation and mercury treatment, based on the coordination chemical characteristics of metallothioneins. The emission completely satisfied these criteria. Furthermore, the reliability of these criteria was supported by immunocytochemical and biochemical results. Consequently, all results sufficiently indicate that the yellowish-orange luminescence in the Long-Evans Cinnamon rat liver is the emission from cuprous metallothioneins.

Animals↗
PubMed1996

Role of milky spots as selective implantation sites for malignant cells in peritoneal dissemination in mice.

We investigated the significance of milky spots for malignant cells in peritoneal dissemination using three mouse carcinomatous peritonitis models. P388 leukemia and Colon 26 cancer cells were labeled with bromodeoxyuridine (BrdU) and mice were inoculated intraperitoneally. After 24 h the greater omentum and the mesenterium were removed and stained immunohistochemically with anti-BrdU antibody. The labeled cells were found to have preferentially infiltrated into the milky spots in these specimens. Next, using B16 PC melanoma cells, which can be easily distinguished from the other cells by the intrinsic black melanin, the distribution of the melanoma cells was observed macro- and microscopically following intraperitoneal inoculation. The melanoma cells were similarly found to have selectively infiltrated into the milky spots in the omentum and mesenterium after 1 day. Moreover, the melanoma cells were growing and forming distinct metastic lesions within the milky spots 1 week later.

Animals↗
PubMed1996

Effects of the synthesized growth hormone releasing peptide, KP-102, on growth hormone release in sodium glutamate monohydrate-treated low growth rats.

KP-102 (D-Ala-D-beta-Nal-Ala-Trp-D-Phe-Lys-NH2), a new second generation hexapeptide, has a potent growth hormone (GH)-releasing action in vivo and in vitro. Here, we evaluated the GH-releasing action of KP-102 under pentobarbital (PB) anesthesia in neonatally sodium-glutamate-monohydrate-treated low growth (NMSG-LG) rats. The plasma GH level in NMSG-LG rats after i.v. administration of KP-102 at 100 micrograms/kg was 1/6.7 (95% C.L. 1/14.7 - 1/3.0) of that in normal rats given the same dose (p < 0.01). However, the increase was significant compared with that in normal rats after saline administration (p < 0.01). The plasma GH releasing action of KP-102 at 100 micrograms/kg i.v. in rats with lesions in the bilateral hypothalamic arcuate nuclei (ARC), was about 1/6.3 (95% C.L. 1/12.4 - 1/3.2) of that in normal rats under PB anesthesia (p < 0.01). When KP-102 was injected into the ARC at doses of 0.0002, 0.02 and 2 micrograms/rat, GH release was dose-related (p < 0.01) under PB anesthesia. KP-102 at 2 micrograms i.c.v. also increased the plasma GH levels (p < 0.01) to about 1/8.3 (95% C.L. 1/22.7 - 1/3.1) of that by systematic administration, at the same potency as the ARC injection (1/13.7 and 95% C.L. 1/37.2 - 1/5.0). These findings suggest that KP-102 potently stimulates the GH release by a direct or indirect antagonism of somatostatin (SRIF) and growth hormone releasing hormone (GHRH) release in the hypothalamus and by a direct action on the pituitary. Furthermore, the GH-releasing action of KP-102 was similar and additive upon both regions in vivo at the maximum effective dose. Moreover, since the GH-release in response to KP-102 administration differed between NMSG-LG and normal rats, and since KP-102 increased the GH release even in NMSG-LG rats, it should be evaluated in the hypophysial GH secretion tests, and may be used to treat the hypophysial GH secretion insufficiency.

Animals↗
PubMed1996

Distribution of Corynebacterium renale among apparently healthy rats.

We examined the distribution of Corynebacterium renale, a causative agent of urinary calculus, in clinically normal rats at 6 animal facilities in Japan. Swabs of the vulva and vaginal vestibule or prepuce of the rats were cultured for isolation of the organisms. C. renale has been isolated at only one animal facility, where cases of urinary calculus were reported several years ago. In this facility, 32% of female (43/135) and 22% of male (18/82) rats, 4-28 weeks old, were positive for C. renale. In contrast, 92 female and 169 male rats at other facilities without a history of the disease were negative for the organisms.

Animals↗
PubMed1996

Sensitive densitometry for the determination of platelet-activating factor and other phospholipids in human tears.

A sensitive TLC method is reported for the determination of the platelet-activating factor (PAF) and other phospholipids in human tears. Tear samples absorbed on filter-paper were subjected to diatomite column extraction with chloroform-methanol. The eluent containing phospholipids was spotted on a silica gel plate. After removing lipids other than phospholipids by pre-development with hexane-diethyl ether (4 + 1 v/v), individual phospholipid separation was carried out by development with chloroform-methanol-water (65 + 35 + 7 v/v). Phospholipase C and then alkaline phosphatase solutions were sprayed on the TLC plate at 45 degrees C to liberate phosphate from each phospholipid. By spray application of a mixture of ammonium molybdate and Malachite Green, the liberated phosphates appeared as blue-green spots of molybdophosphate-Malachite Green aggregate on a yellow-brown background. The absorbance of each spot on the plate was measured at 620 nm with a densitometer. The peak area was found to be linearly related to PAF content in the range 2-100 pmol per spot, the RSD being 2% (n = 7). Approximately 86% of standard PAF added to tears was recovered. By this method, lysophosphatidylcholine (lysoPC), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in human tears could also be detected with high sensitivity. Each phospholipid in healthy human tears showed a nearly constant content; PAF, lysoPC, PC and PE were present at levels of 26.2, 42.3, 10.0 and 19.7%, respectively.

Chromatography, Thin Layer↗
PubMed1996

Significant influence of accompanying chronic hepatitis status on recurrence of hepatocellular carcinoma after hepatectomy. Result of multivariate analysis.

OBJECTIVE: The aim of this study was to evaluate the correlation between the histologic status of accompanying chronic hepatitis and the recurrence rate of hepatocellular carcinoma (HCC) after hepatectomy by multivariate analysis. SUMMARY BACKGROUND DATA: Recent studies have suggested that a considerable number of intrahepatic recurrence of HCC after hepatectomy might be the results of metachronous multicentric hepatocarcinogenesis. The authors hypothesized that the incidence of recurrence due to metachronous multicentric hepatocarcinogenesis would depend on the histologic status of accompanying chronic viral liver disease, which is a main promoter of HCC. METHODS: One hundred ten patients with HCC who underwent curative resection were studied. Histologic status of accompanying chronic hepatitis was classified into the three categories: 1) normal liver or chronic persistent hepatitis (CPH, n = 13), 2) chronic aggressive hepatitis (CAH, n = 50), and 3) liver cirrhosis (LC, n = 47). RESULTS: The Cox multivariate proportional hazard model showed that the accompanying chronic viral hepatitis status (p = 0.0133), extent of hepatectomy (p = 0.0078), and number of tumors (p = 0.0475) were significantly predictive variables for recurrence-free survival. By the log-rank test, recurrence-free survival rate in patients with CPH was significantly higher than those in patients with CAH (p = 0.0005) and LC (p = 0.0075). Patients with CAH had the lowest recurrence-free survival rate (vs. LC, p = 0.028). CONCLUSIONS: The results of this study indicated the significant influence of histologic activity of hepatitis on recurrence of HCC. This might support the concept of significant contribution of multicentric hepatocarcinogenesis to recurrence of HCC after hepatectomy.

Adult↗
PubMed1996

Cisplatin microcrystals suspended in oil: pathological study of acute toxicity in mice.

The pathological changes brought about by the i.p. administration of a new dosage format, cisplatin microcrystals suspended in oil (CDDP-Oil), was examined in mice. CDDP-Oil decreased the absolute weight and the relative weight (organ weight/body weight) of the kidney, liver and spleen in the mice receiving the dosage form. However, the severity of the reduction of the organ weight in the CDDP-Oil administration groups was not different from that in the cisplatin aqueous solution (CDDP-Sol) administration groups. Histologically, severe degeneration and atrophy were recognized in the kidney, large intestine, small intestine, thymus, spleen, bone marrow and lymph nodes in the CDDP-Oil administration groups as well as CDDP-Sol administration groups. However, there were no additional changes in the macroscopic and microscopic findings in the CDDP-Oil groups. From these results, we concluded that this dosage form did not change the toxicity of cisplatin in terms of pathological effects.

Animals↗
PubMed1996

Simple method for detection of Clostridium botulinum type A to F neurotoxin genes by ploymerase chain reaction.

A polymerase chain reaction (PCR)-based method was established to detect each type of neurotoxin genes of Clostridium botulinum types A to F by employing the oligonucleotide primer sets corresponding to special regions of the light chains of the neurotoxins. In this procedure, the PCR products were easily confirmed by restriction enzyme digestion profiles, and as little as 2.5 pg of template DNAs from toxigenic strains could be detected. The specific PCR products were obtained from toxigenic C. botulinum types A to F, a type E toxin-producing C. butyricum strain, and a type F toxin-producing C. baratii strain, but no PCR product was detected in nontoxigenic strains of C. botulinum and other clostridial species. The neurotoxin genes were also detected in food products of a seasoned dry salmon and a fermented fish (Izushi) which had caused type E outbreaks of botulism. Therefore, it is concluded that this PCR-based detection method can be used for the rapid diagnosis of botulism.

Base Sequence↗
PubMed1996

Molecular composition of Clostridium botulinum type A progenitor toxins.

The molecular composition of progenitor toxins produced by a Clostridium botulinum type A strain (A-NIH) was analyzed. The strain produced three types of progenitor toxins (19 S, 16 S, and 12 S) as reported previously. Purified 19 S and 16 S toxins demonstrated the same banding profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), indicating that they consist of the same protein components. The nontoxic components of the 19 S and 16 S toxins are a nontoxic non-hemagglutinin (HA) (molecular mass, 120 kDa) and HA. HA could be fractionated into five subcomponents with molecular masses of 52, 35, 20, 19, and 15 kDa in the presence of 2-mercaptoethanol. The molar ratios of neurotoxins, nontoxic non-HAs, and each HA subcomponent of the 19 S and 16 S toxins showed that only HA-35 of the 19 S toxin was approximately twice the size of that of the 16 S toxin, suggesting that the 19 S toxin is a dimer of the 16 S toxin cross-linked by the 35-kDa subcomponent. The nontoxic non-HA of the 12 S toxin, but not those of the 19 S and 16 S toxins, demonstrated two bands with molecular masses of 106 and 13 kDa on SDS-PAGE with or without 2-mercaptoethanol. It was concluded from the N-terminal amino acid sequences that 106- and 13-kDa proteins were generated by a cleavage of whole nontoxic non-HA. This may explain why the 12 S and 16 S (and 19 S) toxins exist in the same culture. We also found that the HA and its 35-kDa subcomponent exist in a free state in the culture fluid along with three types of progenitor toxins.

Amino Acid Sequence↗
PubMed1996

Modulation of human soleus H reflex in association with voluntary clenching of the teeth.

1. To determine the effects of motor activity in the jaw on more general motor behavior, we examined the modulation of the soleus H reflex in association with voluntary clenching of the teeth in healthy adult volunteers. 2. The amplitude of the H reflex increased remarkably during teeth clenching. The increase during maximal teeth clenching was greater than that induced either by maximal voluntary isometric contraction of the wrist extensors or by maximal voluntary clenching of the fists. 3. The increase in amplitude of the soleus H reflex showed a positive correlation with the strength of teeth clenching, as monitored by recording electromyographic (EMG) activity from the masseter muscle. 4. The increase in amplitude of the H reflex associated with teeth clenching started before the onset of the EMG activity of the masseter muscle, reached a peak shortly after the onset, and then declined to a plateau that continued in parallel with the masseter EMG until the end of teeth clenching. 5. The increase in amplitude of the H reflex in association with teeth clenching was partially decreased during the inhibitory masseteric reflex evoked by innocuous electrical stimulation of the lip. 6. It is concluded that the soleus H reflex is facilitated in association with voluntary teeth clenching, and that descending influences from the cerebral cortex, as well as peripheral afferent impulses from the oral-facial region, are involved in this facilitation. It is proposed that oral motor activity can exert strong influences on the motor activity of the other parts of the body.

Adult↗