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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 775 records · Page 43Linked to original sources
PubMed1991

Activation by spermine of citrate synthase from porcine heart.

Spermine activated citrate synthase from porcine heart by decreasing the Km value for the substrate oxaloacetate without affecting the maximal velocity. Spermine markedly increased the maximal velocity of the saturation function with respect to acetyl-CoA as the substrate under conditions of intracellular concentrations of oxaloacetate, but the enzyme was not activated by spermine under conditions of higher concentrations of oxaloacetate. The concentration of spermine required for 50% activation of the enzyme was about 50 microM. Spermidine showed only a little activation, while putrescine caused no activation. Spermine, which contributes to an activation of Ca2(+)-sensitive dehydrogenases of the citric acid cycle by enhancing Ca2+ uptake into mitochondria, can activate citrate synthase directly, and is responsible for the stimulation of oxidative metabolism in mitochondria.

Animals↗
PubMed1991

Cloning and expression in yeast of a cDNA clone encoding Aspergillus oryzae neutral protease II, a unique metalloprotease.

The neutral protease II (NpII) from Aspergillus oryzae is a zinc-containing metalloprotease with some unique properties. To elucidate its structure, we isolated a full-length cDNA clone for NpII. Sequence analysis reveals that NpII has a prepro region consisting of 175 amino acids preceding the mature region, which consists of 177 amino acids. As compared with other microbial metalloproteases, NpII is found to be unique in that it shares only a limited homology with them around two zinc ligand His residues and that the positions of the other zinc ligand (Glu) and the active site (His) cannot be established by homology. When a plasmid designed to express the prepro NpII cDNA was introduced into Saccharomyces cerevisiae and the transformant was cultured in YPD medium (2% glucose, 2% polypeptone, 1% yeast extract), it secreted a proNpII. However, in a culture of the same medium containing 0.2 mM ZnCl2, it secreted a mature NpII with a specific activity and N-terminus identical to those of native NpII. This observation suggests that either an autoproteolytic activity or a yeast protease effected the processing.

Amino Acid Sequence↗
PubMed1991

Urinary screening of elementary and junior high-school children over a 13-year period in Tokyo.

The School Health Law of Japan was passed in 1974 mandating urine screening of elementary and junior high-school students for the detection of renal disease. A first morning urine was obtained on an annual basis for each individual student for the time period 1974-1986. The prevalence of proteinuria and haematuria among elementary school children was 0.08% and 0.54%, respectively, while junior high-school students demonstrated corresponding prevalences of 0.37% and 0.94%. The theoretical merits of this screening programme include the detection of glomerulonephritis with possible early therapeutic intervention. However, a limitation to this approach is its over-sensitivity where asymptomatic urine abnormalities is found to be 10 times greater in frequency than glomerulonephritis histologically.

Adolescent↗
PubMed1991

Long-term intermittent administration of interferon-alpha in patients with chronic non-A, non-B hepatitis.

IFN-alpha was administered intermittently over a 6 month period in 39 patients with chronic non-A, non-B hepatitis confirmed by peritoneoscopy and liver biopsy. Three million units of IFN-alpha were administered 3 times a week for the first 6 months then twice, then once a week. In 26 patients (67%), GPT decreased and remained within the normal range during the course of administration, and in 9 patients (23%) GPT remained normal for over 6 months after the discontinuation of IFN-alpha. There was no significant difference of efficacy among 3 groups liver histology groups (CPH, CAH-2A, and CAH-2B), but GPT decreased significantly in patients with sporadic hepatitis compared to patients with a history of blood transfusion. Furthermore, GPT decreased significantly in patients with a history of a blood transfusion within the preceding 2 years compared to patients with a history of a blood transfusion over 7 years ago. GPT increased markedly after an early tapering to 2 doses weekly, but it did not increase after a 6 month administration. In conclusion, the long-term administration of 300 million unit IFN-alpha, 3 times weekly for 6 months, about 2.5 hundred million units in total, is thought to be an effective way to control chronic NANB hepatitis.

Adult↗
PubMed1991

Pulmonary hypertension and polymorphonuclear leukocyte elastase after esophageal cancer operations.

To evaluate the role of polymorphonuclear leukocyte (PMN) elastase in pulmonary impairment occurring after operation for esophageal cancer, 10 patients were randomized preoperatively into two equal groups. One group received a placebo infusion and the other, an infusion of the PMN elastase inhibitor ulinastatin. In the placebo group, the mean plasma PMN elastase level increased from 154 +/- 23 micrograms/L preoperatively to 449 +/- 56 micrograms/L at 6 hours postoperatively (p less than 0.01), whereas the mean plasma fibronectin concentration decreased from 490 +/- 70 micrograms/mL preoperatively to 265 +/- 81 micrograms/L on postoperative day 2 (p less than 0.01). The mean pulmonary vascular resistance increased markedly from 151 +/- 24 dynes.s.cm-5.m-2 preoperatively to 284 +/- 76 dynes.s.cm-5.m-2 at 6 hours postoperatively (p less than 0.01). In the group given ulinastatin, 150,000 units every 12 hours from the start of the operation, the mean PMN elastase value at 6 hours postoperatively was lower (275 +/- 66 micrograms/L; p less than 0.01) and the fibronectin level on postoperative days 1 and 2, higher (p less than 0.05). A lower pulmonary vascular resistance was noted into day 2 (p less than 0.05). Our results suggest that PMN elastase may participate in the development of postoperative pulmonary impairment.

Aged↗
PubMed1991

A multifocal schwannoma of the masseteric nerve causing hemicrania.

A case is reported of schwannoma of the right masseteric nerve, invading the pterygopalatine fossa and the parapharyngeal space through the mandibular notch in a 61-year-old woman. The tumor in this case was composed of four various-sized interconnected nodules, simulating a string of beads. The tumor was the cause of the patient's chronic hemicrania, as confirmed by the relief from and disappearance of head pain after surgical removal of the tumor. The most important aspects of this case are the anatomic site of the schwannoma and its uncommon clinicopathologic manifestations; this tumor originated from the masseteric nerve and is the first case reported to straddle the mandibular notch.

Cranial Nerve Neoplasms↗
PubMed1991

12-Keto steroidal glycosides from the caudex of Yucca gloriosa.

Eight new steroidal glycosides, tentatively named YS-VI, -VII, -VIII, -IX, -X, -XI, -XII and -XIII were isolated from the caudex of Yucca gloriosa along with P-1, YG-2 and YG-3 previously obtained from flowers. The structures of five of these compounds were elucidated as mexogenin 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-galactopyranoside (YS-VI), gloriogenin 3-O-beta-D-glucopyranosyl-(1----2)-[beta- D-glucopyranosyl-(1----3)]-beta-D-glucopyranoside (YS-VII) and 3-O-beta-D-glucopyranosyl-(1----2)-[beta-D-glucopyranosyl)-(1----3)]- beta-D-galactopyranoside (YS-VIII), manogenin 3-O-beta-lycotetraoside (YS-IX) and 3-O-alpha-L-rhamnopyranosyl-beta-lycotetraoside (YS-X), respectively, on the basis of chemical and spectral evidence.

Carbohydrate Sequence↗
PubMed1991

12-Hydroxy steroidal glycosides from the caudex of Yucca gloriosa.

The structures of the new steroidal saponins (tentatively named YS-XI, -XII and -XIII) have been isolated from the caudex of Yucca gloriosa and characterized as 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-galactopyranosyl 5 beta- (25R)-spirostan-3 beta, 12 beta-diol, 3-O-beta-D-glucopyranosyl-(1----2)- [beta-D-glucopyranosyl-(1----3)]-beta-D-glucopyranosyl 5 beta- (25R)-spirostan-3 beta, 12 beta-diol and 3-O-beta-D-glucopyranosyl-(1----2)- beta-D-galactopyranosyl 5 beta-(25R)-spirostan-2 beta,3 beta,12 beta-triol, respectively.

Acetylation↗
PubMed1991

Correlation between pain and synovitis in patients with internal derangement of the temporomandibular joint.

A correlation between pain scores by questionnaire and synovitis index via arthroscopic inspection was made in 28 patients with internal derangement of the temporomandibular joint (TMJ) with closed lock. A statistically significant but weak correlation was found between the visual analog scale of pain and the index of distribution of synovitis. However, in the questionnaire, pain on chewing had a positive correlation with both the intensity and distribution of synovitis in the TMJ. This study indicates that synovitis is one cause of TMJ pain in patients with closed lock.

Adult↗
PubMed1991

Equilibrium and kinetic studies of the binding of tri- and tetra-anionic ligands to bovine serum albumin.

The binding of tri- and tetra-anionic azo dyes (Amaranth, Ponceau 4R, and Ponceau 6R) to bovine serum albumin (BSA) at pH = 7.0 and 25 degrees C has been studied by equilibrium dialysis, spectrophotometry, and by stopped-flow and temperature-jump methods. Equilibrium dialysis revealed that BSA has one primary binding site and about two secondary sites for each dye. The values of the binding constant for the primary site show that the stability of the complex at the primary site progressively increases with an increase in the number and the density of anionic charges on ligand. Kinetic data have been found to be consistent with a scheme in which a rapid bimolecular binding is followed by two isomerizations of the complex (in the case of Amaranth) or by one isomerization (in the cases of Ponceau 4R and Ponceau 6R). Equilibrium and rate constants for each step of the scheme were determined. From the results it was found that the increment of the number and the density of anionic charges on ligand accelerates the forward process of the final isomerization step but retards the backward one of it, resulting in the enhancement of the stability of the complex at the primary site. On the basis of these results and the structure of the ligands, the detailed binding mechanism has been discussed in the light of the electrostatic interaction between the ligands and the binding site on BSA.

Animals↗
PubMed1991

Escherichia coli mediated biosynthesis and in vitro anti-HIV activity of lipophilic 6-halo-2',3'-dideoxypurine nucleosides.

A series of 6-substituted 2',3'-dideoxypurine ribofuranosides (ddP) was enzymatically synthesized with live E. coli in an effort to enhance the lipophilicity of this class of anti-human immunodeficiency virus (HIV) compounds and thereby facilitate drug delivery into the central nervous system. All 6-halo-substituted ddPs were substantially more lipophilic, as defined by their octanol-water partition coefficient (P), than their nonhalogenated congeners 2',3'-dideoxyinosine (ddI) or 2',3'-dideoxyguanosine (ddG). For this class of compounds, log P's ranged from +0.5 to -1.2 in the following order: 6-iodo, 2-amino-6-iodo greater than 6-bromo, 2-amino-6-bromo greater than 6-chloro, 2-amino-6-chloro greater than 6-fluoro, 2-amino-6-fluoro much greater than ddG greater than ddI. These compounds were evaluated in vitro for ability to suppress the infectivity, replication, and cytopathic effect of HIV. 2-Amino-6-fluoro-, 2-amino-6-chloro-, and 6-fluoro-ddP exhibited a potent activity against HIV comparable to that of ddI or ddG and completely blocked the infectivity of HIV without affecting the growth of target cells. The comparative order of in vitro anti-HIV activity was 2-amino-6-fluoro, 2-amino-6-chloro, 6-fluoro greater than 2-amino-6-bromo greater than 2-amino-6-iodo, 6-chloro greater than 6-bromo greater than 6-iodo. These compounds also exhibited potent in vitro activity against HIV-2 and 3'-azido-3'-deoxythymidine-resistant HIV-1 variants. All 2-amino-6-halo-ddPs and 6-halo-ddPs were substrates for adenosine deaminase (ADA) and were converted to ddG or ddI, respectively. In the presence of the potent ADA inhibitor 2'-deoxycoformycin, 6-halo-substituted ddPs failed to exert an in vitro antiretroviral effect. These dideoxypurine nucleoside analogues represent a new class of lipophilic prodrugs of ddG and ddI that possess the potential for more effective therapy of HIV-induced neurologic disorders.

Adenosine Deaminase↗
PubMed1991

Foot protein isoforms are expressed at different times during embryonic chick skeletal muscle development.

We have investigated the time course of expression of the alpha and beta triad junctional foot proteins in embryonic chick pectoral muscle. The level of [3H]ryanodine binding in muscle homogenates is low until day E20 of embryonic development, then increases dramatically at the time of hatching reaching adult levels by day N7 posthatch. The alpha and beta foot protein isoforms increase in abundance concomitantly with [3H]ryanodine binding. Using foot protein isoform-specific antibodies, the alpha foot protein is detected in a majority of fibers in day E10 muscle, while the beta isoform is first observed at low levels in a few fibers in day E15 muscle. A high molecular weight polypeptide, distinct from the alpha and beta proteins, is recognized by antifoot protein antibodies. This polypeptide is observed in day E8 muscle and declines in abundance with continued development. It appears to exist as a monomer and does not bind [3H]ryanodine. In contrast, the alpha isoform present in day E10 muscle and the beta isoform in day E20 muscle are oligomeric and bind [3H]ryanodine suggesting that they may exist as functional calcium channels in differentiating muscle. Comparison of the intracellular distributions of the alpha foot protein, f-actin, the heavy chain of myosin and titin in day E10 muscle indicates that the alpha foot protein is expressed during myofibril assembly and Z line formation. The differential expression of the foot protein isoforms in developing muscle, and their continued expression in mature muscle, is consistent with these proteins making different functional contributions. In addition, the expression of the alpha isoform during the time of organization of a differentiated muscle morphology suggests that foot proteins may participate in events involved in muscle differentiation.

Actins↗
PubMed1991

Pulmonary carcinogenicity of 3,9- and 3,7-dinitrofluoranthene, 3-nitrofluoranthene and benzo[a]pyrene in F344 rats.

3,9- and 3,7-Dinitrofluoranthene (3,9- and 3,7-DNF), 3-nitrofluoranthene (3-NF) and benzo[a]pyrene (B[a]P) were tested for pulmonary carcinogenicity by intrapulmonary implantation of the compounds into rat lung. These chemicals were given in various doses as suspensions in beeswax-trycaprylin and the animals were observed for 100 weeks. The control group received no drugs. The incidences of lung tumors were 19/21 (90.5%), 7/10 (70%) and 1/10 (10%) in rats treated with 200, 100 and 50 micrograms of 3,9-DNF, 4/9 (44.4%), 3/10 (30%) and 0/10 (0%) in rats treated with 200, 100 and 50 micrograms of B[a]P, 12/22 (54.5%) in rats treated with 200 micrograms of 3,7-DNF and 1/20 (5%) in rats treated with 1000 micrograms of 3-NF respectively. No lung tumors were found in control rats. The incidence of lung tumors induced by 3,9-DNF was twice as high as that induced by B[a]P, when the equivalent dose levels of the two compounds were compared. Histologically, most of the tumors induced by 3,9- and 3,7-DNF and B[a]P were squamous cell carcinomas.

Animals↗
PubMed1991

Isolation and characterization of recombinant human prorenin in Chinese hamster ovary cells.

Recombinant human prorenin (rh-prorenin) was purified from supernatants of Chinese hamster ovary (CHO) cell line transfected with the cDNA for rh-prorenin by employing a simple two-step procedure which consisted of ammonium sulfate precipitation and immunoaffinity chromatography using a monoclonal antibody specific for the profragment of human prorenin. About 100-fold purification with 35% recovery was achieved after the two steps. Purified rh-prorenin migrated as a single protein band with apparent molecular weights of 46,000-47,000 and about 50,000 on SDS-PAGE and gel filtration (HPLC), respectively, although it consisted of multiple components (pI values, 5.6-6.4) that could be resolved by isoelectric focusing (IEF). The treatment of rh-prorenin with endo-beta-N-acetylglucosaminidase converted the rather broad protein band to a sharp band on SDS-PAGE and reduced the number of multiple pI peaks on IEF. Amino-terminal sequence analysis of both the purified rh-prorenin and rh-renin revealed Leu-Pro-Thr-Asp- and Leu-Thr-Leu-Gly-, respectively, which agreed with those predicted from the base sequences of their cDNA. These data suggested that microheterogeneity of rh-prorenin is due to the carbohydrate moiety, but not to the protein moiety. Purified rh-prorenin was almost inactive, but was cleaved at the carboxyl end of a dibasic pair Lys-2-Arg-1 by trypsin and converted to active renin. However, at the early stage during trypsin activation, new intermediate forms between rh-prorenin and rh-renin were formed, suggesting multiple activation steps of rh-prorenin in addition to the one step activation.

Amino Acid Sequence↗
PubMed1991

Identification of the active site of human renin with use of new fluorogenic peptides.

Fluorogenic peptide substrates were synthesized in which amino acid residues corresponded to the C-terminal and the N-terminal sides of the site of human angiotensinogen cleaved by renin. Compared with the synthetic substrates of renin previously reported, these fluorogenic substrates had practical advantages in that their digestion products could be rapidly separated and sensitively detected by high-pressure liquid chromatography with a fluorescence detector. The recombinant human renin and human plasma split Leu-Val, which cleavage site is similar to that in human angiotensinogen. The kinetic parameters of the reaction of renin using these substrates were calculated. There seemed to be at least eight subsites in the active site of recombinant human renin, to judge from the enzyme-substrate binding characteristics. The two histidine residues (S5 and S'3) in the octapeptide His-Pro-Phe-His-Leu-Val-Ile-His were important in the enzyme action.

Amino Acid Sequence↗
PubMed1991

Cloning and functional expression of a novel endoprotease involved in prohormone processing at dibasic sites.

We cloned and sequenced a cDNA from a library of mouse pituitary AtT-20 cells which are known to cleave an endogenous and various foreign prohormones at dibasic sites. This cDNA encodes a novel 753-residue protein, named PC3, which is structurally related to the yeast Kex2 protease involved in precursor cleavage at dibasic sites and to recently identified mammalian Kex2-like proteins, furin and PC2. Among examined cell lines and tissues, PC3 mRNA was only detected in AtT-20 cells. The substrate specificity of PC3 expressed in mammalian cells was similar to that observed in AtT-20 cells. We conclude that PC3 is a resident prohormone processing endoprotease in AtT-20 cells.

Amino Acid Sequence↗
PubMed1991

Secretory expression of the human serum albumin gene in the yeast, Saccharomyces cerevisiae.

We have fused a cDNA gene encoding mature human serum albumin (HSA) to several secretory leader-encoding sequences. The hybrid genes were cloned into an episomal vector under the control of several yeast promoters and then introduced into yeast cells. The GAL1 promoter in combination with either the native HSA pre-sequence or a modified HSA pre-sequence gave the highest production of immunoreactive HSA, 90 mg/liter being reached in a shake flask culture. The invertase pre-sequence, the mating factor alpha 1 prepro-sequence, and the modified HSA pre-sequence directed accurate processing. In contrast, the chicken lysozyme pre-sequence and the native HSA pre-sequence directed incorrect processing. Episomal vectors were unstable within the host cells under non-selective culture conditions. To improve the plasmid stability, the hybrid genes were incorporated into an integrative vector. Transformants carrying multicopies of the plasmid integrated at the LEU2 locus stably secreted HSA. The highest yield of 65 mg/liter in a shake flask culture was obtained with the combination of the yeast glyceraldehyde-3-phosphate dehydrogenase promoter and the modified HSA pre-sequence. By constructing transformed strains containing multicopies of plasmids integrated at both the chromosome LEU2 and HIS4 loci, we have obtained a stable strain that continuously secretes as much as 85 mg HSA per liter of culture medium.

Amino Acid Sequence↗