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Biomedical subjects

H Masaki

Publications and source records attributed to H Masaki.

At least 235 records · Page 13Linked to original sources
PubMed1991

Use of a triple protease-deficient mutant of Bacillus subtilis as a host for secretion of a B. subtilis cellulase and TEM beta-lactamase.

The mature portion of the TEM beta-lactamase (BLA) gene (bla) derived from pBR322 was fused with the promoter and signal region of Bacillus subtilis cellulase (BSC) gene (bsc), and the productivity was compared with that of the cloned native bsc gene, using a wild-type B. subtilis strain and a strain deficient in three proteases (i.e., extracellular serine protease, extracellular neutral protease, and the major intracellular serine protease) as hosts. The effects of the sen, sacQ, and prtR genes, carried on the same plasmids, were tested as for the productivities of BSC and BLA. The production of BSC was increased 9-fold by using the combination of the triple-protease deficient strain and the sacQ gene, compared with that by using the wild-type strain as a host, and no degradation of BSC was observed in the triple-protease deficient strain. On the other hand, though the production of the BSC-BLA fusion protein increased 2.5-fold in the triple-protease deficient strain, the BLA activity was decreased after the cell reached the stationary phase of growth, possibly due to some proteolysis. These observations show different sensitivity of secretary proteins to cellular proteases, and suggest that BLA is decomposed by remaining minor proteases.

Amino Acid Sequence↗
PubMed1991

[Replacement of the ascending aorta and aortic valve with a composite graft using a reversed St. Jude medical mitral valve prosthesis].

Between 1981 and 1989, ten patients underwent replacement of the ascending aorta and aortic valve by a composite graft for an aneurysm of the ascending aorta with aortic regurgitation. The first two cases using an SJM aortic valve prosthesis and Teflon felt-pledgeted mattress sutures for the proximal anastomoses required a coronary bypass graft from the tube graft to the anterior descending coronary artery because of difficulty in completing the graft-left coronary ostial anastomoses. In the subsequent seven cases, an SJM mitral valve prosthesis with a large, soft cuff for a valved conduit was sewn in reverse and a thin wall Teflon roll was used for the Teflon felt of the pledgeted mattress suture in the proximal anastomoses. As a result, anastomoses between the tube graft and coronary ostia were performed easily and successfully in eight patients. One case with Marfan syndrome required reoperation nine years after the first operation for recurrence of the aneurysm of the aortic arch. Thus, the need for careful and continued follow-up is important in the Marfan syndrome.

Aortic Aneurysm↗
PubMed1991

[Coronary artery bypass surgery in dialysis patient].

In patients with chronic renal failure undergoing hemodialysis for a long period, arteriosclerosis progresses rapidly, and the incidence of ischemic heart diseases is high. We performed coronary artery revascularization in a patient with chronic renal failure complicated by angina pectoris in whom discontinuation of dialysis was sometimes needed for hypotension during dialysis. Her postoperative course was uneventful. Problems in intra and postoperative management of dialysis patients are reported.

Angina Pectoris↗
PubMed1990

Simple monochromatic refractometer for trans-epidermal water loss (TEWL).

We have developed a novel, portable refractometer (Noevir-Eva) for measuring transepidermal water loss (TEWL) which consists of a light emitting diode and a phototransistor. Cobalt chloride is used as an indicator of the amount of water. Filter paper, previously soaked with cobalt chloride solution and then dried, is attached to the skin with tape (3M Blenderm). Then, the monochromatic light (670 nm) which is yielded from the light-emitting diode is irradiated, reflecting on the above-mentioned filter paper, and the intensity of the reflected light is detected by a phototransistor. The amount of water evaporation from the surface of the skin is determined by the unit of reflected light intensity. The measured values by this new apparatus show a linear relationship with those of the commercially available apparatus (Evaporimeter EP-1). Accordingly, this new refractometer for the TWEL proved to be sensitive, dependable and also inexpensive.

Adult↗
PubMed1990

Synergistic effect of thyroid hormone and thyrotropin on iodothyronine 5'-deiodinase in FRTL-5 rat thyroid cells.

The effects of T3 and T4 on the iodothyronine 5'-deiodinase (5'-D) activity in FRTL-5 rat thyroid cells were investigated. T3 and T4 stimulated the 5'-D activity in a dose-dependent manner. Kinetic studies showed that the stimulation of the 5'-D by T3 was associated with an increase in maximum velocity (Vmax) in [11.9 +/- 0.2 (mean +/- SE) and 25.4 +/- 0.9 pmol I-released/mg protein.min, respectively, in control and cultured with 10(-9) M T3 for four days] but without a change in apparent Michaelis-Menten constant (Km) (94.8 +/- 5.3 nM and 105.4 +/- 12.1 nM, respectively). Furthermore, cycloheximide (5 microM) completely abolished the stimulatory effect of T3 on the 5'-D activity. T3 and T4 also enhanced the 5'-D activity stimulated by TSH in a dose-dependent manner. Kinetic studies showed that the stimulatory effect of T3 on the 5'-D stimulated by TSH was again associated with an increase in Vmax (86.0 +/- 4.0 and 166.5 +/- 1.9 pmol I- released/mg protein.min, respectively, cultured with 0.3 U/liter TSH and cultured with TSH plus 10(-9) M T3 for four days) without a change in apparent Km (114.0 +/- 7.4 nM and 111.6 +/- 12.5 nM, respectively). Cycloheximide (5 microM) completely abolished the stimulatory effect of TSH plus T3 on the 5'-D activity. There were no significant differences observed between cells cultured with TSH and with TSH plus T3 in either the intra- or extracellular cAMP contents. Furthermore, T3 enhanced the 5'-D activity stimulated by (Bu)2 cAMP. These results strongly suggest that T3 or T4 was synergistic with TSH in stimulating the 5'-D activity in FRTL-5 cells, and that cAMP production would be an important component of the synergism.

Animals↗
PubMed1990

Graves' immunoglobulin G stimulates iodothyronine 5'-deiodinating activity in FRTL-5 rat thyroid cells.

To elucidate the effect of Graves' immunoglobulin G (IgG) on iodothyronine deiodination in the thyroid, we examined the characteristics of iodothyronine 5'-deiodinating (I-5'-D) activity in FRTL-5 rat thyroid cells and the effect of Graves' IgG on its activity. FRTL-5 cells were sonicated and incubated with 0.5 mumol/L rT3 with a tracer amount of [125I]rT3 in 0.1 mol/L phosphate buffer containing 1 mmol/L EDTA and 0.5 mmol/L dithiothreitol. The released 125I- was separated by Dowex-50WX2 column and counted. The amount of I- released was tissue, incubation time, temperature, and pH dependent, strongly suggesting that the reaction is enzymatic. The activity was completely inhibited by propylthiouracil. The Km value for rT3 was approximately 0.32 microM when analyzed by Lineweaver-Burk plot. TSH, dibutyl cAMP, and Graves' IgG induced I-5'-D activity in a dose-dependent manner. However, cycloheximide (5 mumol/L) abolished the stimulating effects of these agents on I-5'-D activity. These results suggest that TSH, dibutyl cAMP, and Graves' IgG induced I-5'-D activity through the synthesis of new enzyme protein. A significant positive correlation between thyroid-stimulating antibody activity assayed by measuring cAMP production using FRTL-5 cells and I-5'-D activity induced by the Graves' IgG in 10 patients with untreated Graves' disease was observed (r = 0.79; P less than 0.01). The present findings suggest that type I iodothyronine 5'-deiodinase exists in FRTL-5 rat thyroid cells and that Graves' IgG as well as TSH stimulate the activity at least in part by activating adenylate cyclase.

Animals↗
PubMed1990

Effects of H+ and HCO3- secretion on mucus gel pH in isolated antral mucosa of bullfrog stomach.

To study the mechanism of self-protection of the gastric surface epithelium, we measured the pH gradient of the mucus gel layer in the isolated bullfrog antral mucosa with pH-sensitive microelectrodes in the Ussing chamber preparation. Under the control condition of 15mM HCO3- and 1.5% CO2 serosal perfusion, the pH on the interface between luminal solution and mucus gel layer (pHLMI) was 6.04 +/- 0.12 (n = 7), and the pH on the interface between the mucus gel layer and epithelial cell (pHMEI) was 5.69 +/- 0.13 (n = 7). When gastric acid secretion was stimulated by histamine (10(-4) M), the pHLMI became 5.43 +/- 0.12 (n = 4) and the pHMEI 4.40 +/- 0.18 (n = 4). Inhibition of acid secretion by cimetidine (10(-4) M) raised the pHLMI to 6.51 +/- 0.07 (n = 7) and the pHMEI to 6.23 +/- 0.08 (n = 7). Omeprazole (10(-4) M) also raised the pHLMI and the pHMEI to 6.78 +/- 0.13 (n = 7) and 6.56 +/- 0.13 (n = 7), respectively. These data suggested that the H+ ions secreted from the oxyntic cells were able to diffuse to the lateral side within the mucus gel layer, affecting the local pH just above the surface epithelial cells. Under high serosal HCO3- condition (45mM HCO3- and 1.5% CO2 in serosal side), the pHLMI and the pHMEI were elevated to 7.22 +/- 0.10 (n = 7) and 6.92 +/- 0.10 (n = 7), respectively. This result suggested that HCO3- secretion, which was served to neutralize the invading acid, depended upon the supply of HCO3- from the serosal medium. Thus, the serosal HCO3- would be working not only in the acid-protection, but also in the maintenance of pH gradient across the mucus gel layer.

Acid-Base Equilibrium↗
PubMed1990

[Factors related to prognosis and relapse in acute myelomonocytic and monocytic leukemias (M4 and M5)].

To analyse the factors which were related to prognosis at first examination and early diagnosis of relapse in complete remission phase, 26 patients with acute myelomonocytic leukemia (M4) and acute monocytic leukemia (M5) were investigated. There was a tight relationship between age and remission rate in patients with M4 and M5. Six of M4 with eosinophilia (M4Eo) patients revealed 83.3% as remission rate with good prognosis in the survival curve. LDH level of them was lower than other patients significantly. In order to diagnose relapse before clinical manifestations, it was useful to follow up number of mature monocytes (over 600/microliters) in the peripheral blood.

Adolescent↗
PubMed1990

[Estimating the quality of life in childhood cancer survivors from parent questionnaires].

Multidisciplinary clinical research on childhood cancer has achieved a marked improvement in survival rate during the last two decades. Due to the increase of long-term survivors, the survey of quality of life (QOL) of cured children is essential. But methods to estimate QOL of children have not been established. We attempted to estimate the QOL of surviving patients from the responses to a questionnaire filled out by their parents. The total number of patients treated at the National Children's Hospital from 1965-1987 was 937, of which 296 patients are still surviving. Among these survivors 108 patients were selected to be surveyed because they were being followed up by our attending physicians. The originally elaborated questionnaire was sent to parents in June 1989. Seventy-eight parents responded. The questionnaire consisted of four major questions. The first was how the QOL of the child compared to that of an ordinary child. The parents circled the appropriate level of QOL determined by our scale (1 lower, 4 the same as ordinary child, 7 excellent). The average score was 5.61 showing that parents felt their child's QOL is superior to an ordinary child. The second question concerned how the present status of the child was influenced by the experience of cancer. Answers were divided into five categories as follows: 1) Good or positive (10%); 2) nothing in particular (49%); minimum (29%); negative (9%); and other (7%). The third question concerned any anxieties. Most parents had numerous anxieties about the relapse, late effects, education, job prospects, marriage and offspring and getting the latest information. The fourth question dealt with what to tell the child as to their true diagnosis. Answers were divided as follows: absolutely no (56%); yes, but in the future (23%); yes, already done (10%); and yes, through our physician; (13%). After studying the questionnaires we interviewed the parents. We noticed that the parent/child relationship was very close. A meeting was conducted with parents and all the staff (doctors, psychologists and nurses). In conclusion, the QOL in surviving childhood cancer patients is considered to be better than that of ordinary children by their parents. This result is likely due to the excellent parent/child relationship.

Adolescent↗
PubMed1989

Sequence and characteristics of the Bifidobacterium longum gene encoding L-lactate dehydrogenase and the primary structure of the enzyme: a new feature of the allosteric site.

The gene ldh, encoding L-lactate dehydrogenase (LDH; EC 1.1.1.27) of Bifidobacterium longum aM101-2, was cloned in Escherichia coli using an oligodeoxyribonucleotide hybridization probe. The amino acid (aa) sequence, deduced from the sequence of the cloned DNA, was consistent with the results of protein chemical analysis of B. longum LDH. The transcription start points (tsp) in B. longum were identified by S1 nuclease mapping. A sequence, GTAGCAA-(14 bp)-TTATAGA, which is located a few bp upstream from the tsp, was assigned as the promoter of this ldh gene. In the 3'-noncoding region, there were two structures that strongly resembled the Rho-independent transcriptional termination signal of E. coli. Therefore, the B. longum ldh gene might form a monocistronic unit. The deduced primary structure of B. longum LDH had 40% identity with LDHs from Thermus caldophilus, Bacillus stearothermophilus, Lactobacillus casei and dogfish muscle. Most bacterial LDHs are allosterically regulated by fructose 1,6-bisphosphate (FBP), while the vertebrate LDHs are not. The anion-binding site of vertebrate LDHs has been thought to correspond to the FBP-binding site of bacterial LDHs. Although the B. longum LDH was regulated by FBP, the charge properties of aa residues in the putative FBP-binding site of the LDH were closer to those of the vertebrate LDHs than to those of bacterial LDHs.

Allosteric Site↗
PubMed1989

Coronary flow velocity waveforms in aortic stenosis and the effects of valve replacement.

In 6 patients with pure aortic stenosis, the flow velocity waveforms in the left anterior descending coronary artery were studied using an 80-channel 20-MHz pulsed Doppler velocimeter before and immediately after aortic valve replacement. All patients showed normal coronary arteriograms. The left anterior descending coronary artery flow velocity waveform in aortic stenosis was characterized by a reverse flow in the first half of systole and a slowly increasing diastolic inflow. After aortic valve replacement, the reverse flow in the first half of systole disappeared in all patients, but an end-systolic reverse flow was discerned in 5 of 6 patients. The increasing rate of the diastolic inflow was augmented in all patients. After aortic valve replacement, the time from onset of diastole to the diastolic peak velocity was shortened from 176.8 +/- 28.8 to 90.5 +/- 18.8 ms (p less than 0.01), and the diastolic peak velocity increased from 90.5 +/- 28.0 to 122.5 +/- 17.2 cm/s (p less than 0.05). Blood pressure and heart rate, however, did not change significantly before and after valve replacement. These changes in the left coronary artery velocity waveforms after valve replacement suggest the beneficial effects of removal of aortic stenosis on human coronary artery inflow.

Aortic Valve↗
PubMed1989

Pemphigoid nodularis.

A 61-year-old man with prurigo nodularis subsequently developed bullous pemphigoid. Direct immunofluorescence studies of a prurigo nodularis-like lesion and peribullous skin showed the deposition of IgG, IgA, and C3 in a linear pattern at the basement membrane zone. Indirect immunofluorescence studies disclosed circulating anti-basement membrane zone antibodies. Immunoelectron microscopy revealed IgG, IgA, and C3 distributed in the lamina lucida and on the undersurface of the basal keratinocytes in both peribullous and prurigo nodularis lesions. These findings confirmed the diagnosis of pemphigoid nodularis.

Complement C3↗
PubMed1989

Molecular structure and immunity specificity of colicin E6, an evolutionary intermediate between E-group colicins and cloacin DF13.

The primary structure of a 3.1-kilobase E6 or E3 segment carrying colicin and related genes was determined. Plasmid ColE6-CT14 showed striking homology to ColE3-CA38 throughout this segment, including homology to the secondary immunity gene, immE8, downstream of the E6 or E3 immunity gene. The ColE3-CA38 and ColE6-CT14 sequences, however, contained an exceptional hot spot region encoding both the colicin-active domain (RNase region) and the immunity protein, reflecting their different immunity specificities. On the other hand, some chimeric plasmids were constructed through homologous recombination between colicin E3 and cloacin DF13 operons. The resulting plasmids were deduced to produce chimeric colicins with a colicin E3-type N-terminal part, a cloacin DF13-type C-terminal-active domain, and the DF13 immunity protein. The killing spectra of the chimeric colicins and the immunities of the plasmids were identical to those of colicin E6 and ColE6-CT14, respectively, showing that the colicin E6 immunity specificity is completely equivalent to that of cloacin DF13. Nevertheless, colicin E6 has been found to show a sequence diversity from cloacin DF13 almost to the same extent as that from colicin E3 in their RNase and immunity regions, indicating that only a small number of amino acids defines the immunity specificity for discrimination between colicins E3 and E6 (or cloacin DF13).

Amino Acid Sequence↗
PubMed1989

Intracellular pH of gastric surface epithelial cells exposed to HCl and ethanol.

Ultramicro-pH electrodes were used to determine intracellular pH changes induced by luminal perfusion of acid and alcohol in the gastric mucosa. In preparations of the bullfrog antral mucosa mounted on a horizontal type Ussing chamber, we determined intracellular pH (pHi) in situ of the surface epithelial cells exposed to HCl in the presence or absence of 10% ethanol in the luminal side. The pHi and apical membrane potential (LEM) of the surface epithelial cells were measured with double-barreled liquid ion-exchanger pH microelectrodes. In normal control conditions, the mucosal pHi was 7.43 +/- 0.01 and LEM was 29.5 +/- 0.7 mV (SE, n = 54). Acidification of luminal perfusate to pH 3.5 had no influence on pHi. Exposure to luminal 1 mM HCl (luminal pH: pHL = 3.1) lowered pHi to 7.31 +/- 0.01 (n = 6). Addition of 10% ethanol (EtOH) to luminal perfusate at pH 4.2 (0.1 mM HCl) led to immediate and progressive acidification of pHi (delta pHi = 0.12 +/- 0.02, n = 6). Hyperpolarization of LEM (by several mV) was also observed under such conditions, indicating an altered ion permeability of the apical membrane. These results suggest that even a low concentration of alcohol added to the gastric lumen causes a significant change in the surface epithelial cells, and this change becomes manifest when the luminal fluid is acidified to pH lower than 4.

Animals↗
PubMed1989

[Improved method for combined agar/alginate hydrocolloid impression. Bond strength of combination agar-gel/alginate].

The authors have been developing an improved method that an alginate mix is applied to gelled agar to obtain precise impressions. In the present study, the bond strength of the improved method was investigated. Thirty-one agar impression materials and thirteen alginate impression materials were used. The tensile-bond strength between an alginate (VAd) and various agars (exp. 1), and between an agar (DBRS) and various alginates (exp. 2), was measured by means of the Instron Testing Machine (model 1123) operated at a cross-head speed of 500 mm/min. The bond strength varied with the combinations of the products of agar and alginate. The bond strength of some combinations was higher than the stress in removing impressions from the mouth. Comparing the products of the same manufacture, the bond strength varied with the different colors (composition) of agar, but didn't vary with the different types of cartridge++ or syringe. The result suggested that the bond strength between agar and alginate depended, not only on the agar, but also on the alginate.

Agar↗
PubMed1989

[Effects of nitroglycerin on the graft flow during aortocoronary bypass surgery].

The effects of an intravenous infusion of nitroglycerin on the hemodynamics and bypass graft flow to left coronary artery were studied in sixteen patients during coronary artery surgery. Systolic blood pressure, cardiac output and left ventricular minute work were not affected by 0.2 microgram/kg/min of nitroglycerin but graft flow volume especially diastolic graft flow increased significantly and the characteristics of flow velocity waveform in the graft became more diastolic predominant. By 1 microgram/kg/min of nitroglycerin a significant decrease in systolic blood pressure, cardiac output and graft flow were recognized, however diastolic graft flow was preserved despite of a decrease in left ventricular minute work. These findings demonstrate that nitroglycerin can be safely administered intravenously during aortocoronary bypass surgery, and suggest that nitroglycerin improves the balance of myocardial oxygen demand and supply, and relieves myocardial ischemia.

Animals↗