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Biomedical subjects

E Kobayashi

Publications and source records attributed to E Kobayashi.

At least 343 records · Page 19Linked to original sources
PubMed1992

A polymorphism detected in a variable number of tandem repeats (VNTR) of the seminal vesicle secretion (SVS) IV gene in inbred rats.

The second intron of the rat SVS IV gene contains a tandem repeat region of 20-bp sequences. This region was amplified using the polymerase chain reaction to detect variations. Three alleles, characterized by amplified fragments of 750, 490, and 390 bp, respectively, were found in 24 strains examined. This variation segregated in F1 and backcross progeny in an autosomal codominant manner. We tentatively designated this locus Svs-4. Analysis of linkages between the Svs-4 locus and other loci revealed that it was closely linked to the Svp-1 (less than 2.9%) and the a (10.0 +/- 6.7%) loci, which belong to rat linkage group IV. The Svp-1 and Svs-4 loci, however, were differently distributed among the inbred rat strains.

Alleles↗
PubMed1992

Malignancy and viability of intraparenchymal brain tumours: correlation between Gd-DTPA contrast MR images and proliferative potentials.

The feasibility of diagnosing the malignancy and viability of intraparenchymal brain tumours using Gd-DTPA, enhanced and unenhanced T1-weighted MRIs was investigated. The relationship between the Gd-DTPA enhancement pattern, the growth fraction (GF) determined by using the anti-bromide-oxyuridine (BrdU) monoclonal antibody, the clinical condition, the proliferative potential and the change of Gd-DTPA enhancement over time was studied. Forty-five patients with intracranial tumours were studied with the static method of Gd-DTPA MRI. The enhanced effect in Gd-DTPA MRIs was dependent on tumour-cell density, vascularization, necrosis, and dilatation of vascular lumen. Tumour-cells were observed in eighty-seven of eighty-nine specimens taken from areas with Gd-DTPA enhanced MRIs. Seventy-four percent of these specimens (64 of 87) showed a malignancy of more than 5% growth fraction. On the other hand, tumour cells were observed in twenty-seven of fifty-six specimens taken from areas with Gd-DTPA unenhanced MRIs. Eighty-five percent of these specimens (23 of 27) showed a malignancy value of less than 5% GF. However, fifteen percent of these specimen showed values between 5 and 15% GF. In the kinetic study of Gd-MRIs five patients who were in a clinically stable condition and one patient who had radionecrosis showed a constant pattern of enhancement or slightly increased enhancement 30 min after injection compared to 4 min after injection. Therefore, GD-DTPA MRI can be used effectively in the diagnosis of tumour viability and malignancy after treatment.

Brain↗
PubMed1992

Kinetic mechanism of reduction of testosterone by hepatic 5 beta-reductase of chicken and inhibition of the reductase activity by a secosteroid, an azasteroid and glycyrrhetinic acid.

The present studies on initial velocity of testosterone reduction by hepatic 5 beta-reductase (4-en-3-oxosteroid 5 beta-reductase) of chicken and mode of inhibition of the 5 beta-reduction by 5 beta-dihydrotestosterone and NADP+ indicated that the reduction of testosterone occurred after the 5 beta-reductase bound firstly to NADPH and then to testosterone, forming a ternary complex. After 5 beta-reduction, 5 beta-dihydrotestosterone and then NADP+ were liberated from the complex, following a mechanism of "ordered Bi-Bi". Effect of (4R)-5,10-seco-19-norpregna-4,5-diene-3,10,20-trione (a steroidal 5 alpha-reductase-inhibitor or Secosteroid), diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide (the other steroidal 5 alpha-reductase-inhibitor or 4-MA), and glycyrrhetinic acid (3 beta-hydroxy-11-oxoolean-12-en-30-oic acid, a 5 beta-reductase-inhibitor) was examined upon the 5 beta-reductase activity by double reciprocal plots. The mode of inhibition against testosterone by 4-MA and glycyrrhetinic acid was found to be competitive, while that by Secosteroid was non-competitive.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1992

Sexing of mouse preimplantation embryos by detection of Y chromosome-specific sequences using polymerase chain reaction.

Detection of genes known to be present on the mammalian Y chromosome was adapted for sexing mouse early embryos using the polymerase chain reaction (PCR) method. Sry and Zfy genes located in the sex-determining region of the Y chromosome were chosen for Y-specific target sequences, and DXNds3 sequence on the X chromosome was chosen for control. The two-step PCR method using two pairs of primers for each of the target sequences was employed for detecting the sequences. When DNAs of male and female mice were amplified with these primers, male-specific fragments were detected even in DNAs that were equivalent in amount to two cells. Mouse embryos at the two-cell stage were separated into two individual blastomeres, and one blastomere was karyotyped at the second cleavage. The remaining blastomere was subjected to PCR amplification immediately or after having been cultured for 48 h up to the morula stage. The Sry and Zfy sequences were detected in about half the embryos; detection of the Sry and Zfy sequences corresponded exactly to the presence of the Y chromosome, except in one sample of male morula in which embryos may have been lost before the PCR amplification. It is concluded that the sex of mouse preimplantation embryos can be accurately determined through detection of the Y-specific sequences using the two-step PCR method, even with the single blastomeres separated at the two-cell stage.

Animals↗
PubMed1992

Anticellular and antitumor activity of duocarmycins, novel antitumor antibiotics.

The anticellular and antitumor activities of novel antitumor antibiotics, duocarmycins (DUMs), were examined against human and murine tumor cells. DUMs consist of five compounds, A, B1, B2, C1 and C2, which possess a pharmacophore similar to that of CC-1065, a previously isolated antibiotic. Among them, DUMA exhibited ultrapotent growth-inhibitory activity with an IC50 value of 6 pM against human uterine cervix carcinoma HeLa S3 cells. DUMA and DUMB1 also inhibited the growth of adriamycin (ADM)-resistant lines of human nasopharynx carcinoma KB cells and breast carcinoma MCF-7 cells as well as their sensitive lines. DUMs inhibited the growth of s.c.-inoculated murine tumors such as B16 melanoma, sarcoma 180, M5076 sarcoma and colon 26. DUMs were also significantly effective in increasing the lifespan of i.p.-inoculated B16 melanoma-bearing mice, although their effect was marginal against other i.p.-inoculated tumors. As a whole, DUMB1 exhibited superior activity to the other four compounds. DUMB1 rapidly inhibited the incorporation of [3H]-TdR into macromolecules of HeLa S3 cells as compared with that of [3H]UR or [3H]leucine. DNA strand breaks were detected in DUMB1-treated HeLa S3 cells by agarose gel electrophoresis with a contour-clamped homogeneous electric field apparatus. These results indicate that DUMs possess interesting biological activities as DNA-targeting antitumor antibiotics.

Animals↗
PubMed1992

Wear of denture teeth by use of metal plates. Part 2: Abrasive wear of posterior teeth.

An in vitro study was conducted to evaluate the abrasive wear resistance of high-strength denture teeth (HS teeth). Eight types of specimen were used in the experiments; 3 types of HS teeth, 3 types of conventional plastic denture teeth (PL teeth), porcelain teeth and metal teeth. Sliding-induced wear tests were conducted by sliding the samples on a metal plate. The abrasive wear resistance of the samples was evaluated in terms of wear depth, weight loss and SEM observation. Comparison of wear depth showed that abrasive wear resistance of HS teeth was 4.7 times that of PL teeth, 0.7 times that of porcelain teeth and 8.3 times that of metal teeth. In terms of weight loss, the corresponding values were 3.3-fold, 0.2-fold and 11.4-fold, respectively.

Dental Porcelain↗
PubMed1992

Wear of denture teeth by use of metal plates. Part 3: Abrasive wear of posterior teeth and wear of opposing metal plates.

An in vitro evaluation of abrasive wear resistance of high-strength denture (HS) teeth and wear of metal plates (Pd alloy) on the opposing side was conducted. A total of 8 types of teeth were used in the experiments including 3 types of HS teeth, 3 types of conventional plastic denture (PL) teeth, porcelain teeth and metal teeth (Pd alloy). Sliding-induced wear tests were conducted by sliding these teeth over the metal plates. Abrasive wear resistance of the teeth was evaluated in terms of wear depth and weight loss. A comparison of wear depth showed that the abrasive wear resistance of HS teeth was 4.7 times that of PL teeth, 0.7 times that of porcelain teeth and 8.3 times that of metal teeth. Weight loss showed that the abrasive wear resistance of HS teeth was 3.3 times that of PL teeth, 0.2 times that of porcelain teeth and 11.4 times that of metal teeth. The weight loss of the metal plates was minimal when they slid over HS teeth, but increased in the order PL teeth, porcelain teeth and metal teeth.

Dental Alloys↗
PubMed1991

Inhibition of protein kinase C by calphostin C is light-dependent.

Calphostin C, a secondary metabolite of the fungus Cladosporium cladosporioides, inhibits protein kinase C by competing at the binding site for diacylglycerol and phorbol esters. Calphostin C is a polycyclic hydrocarbon with strong absorbance in the visible and ultraviolet ranges. In characterizing the activity of this compound, we unexpectedly found that the inhibition of [3H]phorbol dibutyrate binding was dependent on exposure to light. Ordinary fluorescent light was sufficient for full activation. The inhibition of protein kinase C activity in cell-free systems and intact cells also required light. Light-dependent cytotoxicity was seen at concentrations about 5-fold higher than those inhibiting protein kinase C.

Animals↗
PubMed1991

Antitumor activity of 7-N-[[2-[[2-(gamma-L-glutamylamino)ethyl]dithio]ethyl]]-mitomycin C.

Through the extensive investigation of new mitomycin C (MMC) derivatives, several compounds with disulfide at N-7 were found to show activities superior to MMC against murine Sarcoma 180 solid tumor. Among them, 7-N-[[2-[[2-(gamma-L-glutamylamino)ethyl]dithio]ethyl]]- mitomycin C (KW-2149) was selected for further evaluation of antitumor activity and toxicity in mice. KW-2149 exhibited activity superior to MMC in increasing survival of i.p. inoculated P388 leukemia-, M5076 sarcoma-, and B16 melanoma-bearing mice. KW-2149 administered i.v. also exhibited superior activity in inhibiting the growth of s.c. inoculated P388 leukemia, M5076 sarcoma, and colon 26 adenocarcinoma and in increasing survival of i.v. inoculated P388 leukemia- and M5076 sarcoma-bearing mice. Furthermore, KW-2149 remarkably increased the life span of MMC-resistant P388 leukemia- and L1210 leukemia-bearing mice. KW-2149 and MMC inhibited the growth of human tumors inoculated into nude mice. The activity of KW-2149 was prominent in human lung carcinoma Lu-65 and Lu-99, bladder carcinoma T24, and epidermoid carcinoma A431. KW-2149 was comparable to MMC in decreasing the number of WBC in the peripheral blood, and the thrombopenia induced by KW-2149 was mild and recovery was rapid. The in vitro anticellular spectrum of KW-2149 against 23 human tumor cell lines was similar to that of MMC. However, KW-2149 inhibited the growth of the cell lines at concentrations of 10- to 100-fold lower than MMC and showed efficient cytotoxicity against MMC-insensitive tumor cell lines. These included lung epidermoid carcinoma Calu-1, stomach carcinoma MKN-28, colon adenocarcinoma DLD-1, colon adenocarcinoma LoVo, bladder carcinoma HT-1197, sarcoma G-292, and melanoma SK-MEL-28 cells. These results indicate that KW-2149 bears interesting characteristics as a new anticancer drug and warrants further development.

Animals↗
PubMed1991

Changes in element concentration and distribution in breast-milk fractions of a healthy lactating mother.

Daily changes in components of breast milk with number of days of lactation after delivery were demonstrated by determining concentrations and distributions of several elements simultaneously. Concentrations of calcium, copper, magnesium, phosphorus, sulfur, and zinc were determined simultaneously by inductively coupled argon plasma-atomic-emission spectrometry (ICP) for whole milk and milk fractions (skimmed milk and whey) collected from 2 to 196 d postpartum from a healthy lactating mother. Calcium and phosphorus concentrations increased in transitional milk. With days postpartum, the other elements decreased from the highest concentrations in colostrum milk, the modes of decrease being characteristic for each element. Distributions of copper, iron, phosphorus, sulfur, and zinc in whey were determined on a gel-filtration column by HPLC with ICP detection (HPLC-ICP method). Distributions of the five elements and absorbance peaks at 254 and 280 nm changed dramatically day by day at the beginning (colostrum milk), resulting in constant distributions after 30 d (mature milk). These results suggest the important roles of daily changing constituents in breast milk, especially in colostrum milk, in the nutrition of the newborn. Several element peaks on a gel-filtration column were identified by comparison with standard samples.

Adult↗
PubMed1991

Biological discrimination between calcium and strontium in kidneys and bone of young and adult rats.

Effects of aging on the biological discrimination between calcium (Ca) and strontium (Sr) by the kidneys and bone were studied in male and female rats of 5 to 50 wk of age by examining Sr/Ca ratios in the plasma, urine, and bone. The Ca-Sr discrimination at the reabsorption process in the kidneys was not affected by aging in male or female rats. On the other hand, discrimination between the two elements was shown to be age-related at the absorption process in the digestive tract, and became more strict with age. The reverse situation was observed in the discrimination of Ca and Sr in the femur; younger rats discriminated the two elements more strictly than older animals.

Aging↗
PubMed1991

Aspergillus mycotic aneurysm--case report.

A 61-year-old female developed subarachnoid hemorrhage after trans-sphenoidal surgery for Rathke's cleft cyst. Neuroradiological examination revealed a large aneurysm at the C1 portion of the right internal carotid artery. Autopsy revealed marked proliferation of aspergillus hyphae in the wall of the aneurysm. A review of previously reported cases of fungal aneurysm proposes two developmental processes. Aneurysms secondary to fungal meningitis tend to be large in size and located in the major cerebral artery trunk, but aneurysms following fungal sepsis tend to be small and in peripheral branches. The former aneurysms are probably caused by fungus invasion into the intracranium, usually from the paranasal sinus, and the latter may be due to fungal emboli like bacterial emboli in bacterial endocarditis. Ruptured fungal aneurysms are difficult to treat, so fungal meningitis or sepsis must be eradicated before an aneurysm develops.

Aneurysm, Infected↗