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Biomedical subjects

R Okamoto

Publications and source records attributed to R Okamoto.

At least 199 records · Page 11Linked to original sources
PubMed1990

Gradual low riding of the patella during postoperative course after total knee arthroplasty in osteoarthritis and rheumatoid arthritis.

Patellar height in the lateral view of radiograms was measured on 94 knees of 61 women before and after total knee arthroplasty in order to study postoperative changes of position. The mean age of patients at surgery was 58.4 years (range, 30-77 years). Eighty-one knees were rheumatoid and 13 osteoarthritic. Inserted prostheses were Kinematic anteriorly joined type in 49 knees, Kinematic posterior cruciate retention type in 19, and UCI type in 26. The observation period ranged from 6 months to 9 years, with an average of 2.6 years after surgery. The ratio of length of the patellar ligament to that of the patella (Insall-Salvati's ratio) decreased by more than 10% of preoperative value in 61 knees, remained unchanged in 31, and increased in only 2. The average ratio was 0.93 +/- 0.16 before surgery and 0.75 +/- 0.20 at the final follow-up examination (P less than .01).

Adult↗
PubMed1990

Significance of arterial ketone body ratio measurement in human liver transplantation.

Arterial ketone body ratio (KBR), which reflects the NAD+/NADH ratio of hepatic mitochondria, was measured sequentially in 39 liver transplantations. In 22 cases, KBR was increased to above 0.7 within 6 hr after reperfusion (group A). In 11 cases, restoration of KBR was delayed until the first postoperative day (group B) and in 6 cases, KBR failed to recover (group C). The patients in group A survived liver transplantation without complications. By contrast, morbidity and mortality were significantly higher in groups B and C. In 2 cases in group C, the livers were clinically diagnosed as initially nonfunctioning grafts and the patients underwent retransplantation. Another two died of hepatic failure soon after the operation. It is suggested that delayed recovery of KBR is an early indicator of metabolic overload in the liver allograft, and that a delay exceeding 24 hr may imply the need for retransplantation.

Adult↗
PubMed1990

[Clinical results of total knee arthroplasty using Kinematic type in patients with rheumatoid arthritis under the age of 50 years].

We reviewed 24 total knee arthroplasties using Kinematic type (anteriorly joined type or posterior cruciate retention type) in 18 rheumatoid patients who were under the age of 50 years. Thirteen knees with Kinematic type total knee arthroplasty in 10 rheumatoid patients who were over 70 years of age were also reviewed. Using rheumatoid arthritic knee rating score of J.O.A. (Japan Orthopedic Association), the clinical results of young patients were evaluated and were compared with those of elderly patients. The average total score of young patients and that of older patients was almost equally increased after arthroplasty. Postoperatively in older patients, pain score was elevated more remarkably than in young patients. However, increase in score of quadriceps muscle strength, walking ability and climbing stairs ability were less in older patients than that in young patients. Range of motion was not improved in both young and older patients. However, flexion contracture was improved remarkably in both groups.

Adult↗
PubMed1990

[A solitary extramedullary plasmacytoma of the nasopharynx].

A 72-year-old male, complaining of epistaxis, was referred to our hospital where a physical exam revealed a tumorous mass in the nasopharynx. A subsequent immunohistopathological investigation found that the tumor mass was a plasmacytoma with IgG and a lambda chain. Electrophoresis of a serum sample revealed a normal value and there was no signs indicating a multiple myeloma on x-ray surveys of the skeleton, or from bone marrow aspiration or scintigraphy. Thus the diagnosis was an extramedullary plasmacytoma and the patient received a combined treatment of chemotherapy, radiotherapy, and surgery. Since surgery, the patient has had neither a recurrence or a metastasis of the tumor for four years and three months.

Aged↗
PubMed1990

In vitro antimicrobial activity of a novel aminothiazolylglycylcephalosporin, MT0703S, compared with that of ceftazidime, cefoperazone and aztreonam.

The antibacterial activity of a novel aminothiazolylglycylcephalosporin, MT0703S, possessing a dihydroxypyridone moiety was compared in vitro with the activity of ceftazidime, cefoperazone, aztreonam and other beta-lactam antibiotics using seven bacterial species of a clinical origin. MT0703S showed the most potent activity against P. aeruginosa, including the ceftazidime-resistant strains, E. coli, K. pneumoniae and C. freundii. MT0703S was comparable to aztreonam but more active than ceftazidime and cefoperazone in its activity against K. oxytoca and E. cloacae, and comparable to ceftazidime against S. aureus and S. marcescens. MT0703S was more active than cefoperazone against S. marcescens but less active against S. aureus. The stability of MT0703S against various beta-lactamases appeared to be intermediate between the stability of ceftazidime and that of cefoperazone. The antimicrobial activity of MT0703S increased in a low-iron environment and decreased in a high ferric ion concentration.

Aztreonam↗
PubMed1990

Hepatic resection for advanced hepatocellular carcinoma with removal of portal vein tumor thrombi.

In 13 of 398 patients who underwent hepatectomy, tumor thrombi of the remnant portal vein was concomitantly removed by the balloon catheter method in 8, an open method under hepatic vascular exclusion in 1, and resection of the occlusive portal segment followed by portal reconstruction in 4. In 8 of these patients the liver was cirrhotic. The mode of hepatectomy consisted of bisegmetectomy or trisegmentectomy in 11, segmentectomy in one, and partial resection in one patient. Two patients died of portal thrombosis or hepatic failure in the hospital. The mean survival in four patients was 12 months. Seven are still alive (mean, 16 months). In the corresponding period, nine patients with occlusive tumor thrombi of the portal confluence were hospitalized without operation and survived up to 4 months (mean, 64 days) after detection of the tumoral occlusion. The causes of death of the nine patients were bleeding esophageal varices, rupture of the tumor, or hepatic failure. It was revealed that removal of tumor thrombi in the remnant portal vein contributes to (1) portal decompression, (2) feasibility of arterial embolization, and (3) increase in resectability of the main tumor. At present, this procedure might be regarded as an emergency procedure for the avoidance of the above lethal impendence, but it may open the door to an adjuvant therapy.

Aged↗
PubMed1990

Evaluation of the liver graft before procurement. Significance of arterial ketone body ratio in brain-dead patients.

Hepatic energy metabolism was assessed by measuring the blood ketone body ratio (KBR), that is, the ratio of acetoacetate to beta-hydroxybutyrate in the arterial blood, in 31 brain-dead patients in an intensive care unit (ICU) in Japan and in 25 donors just before procurement of the liver for transplantation in Germany. In the study in Japan, 7 of the 12 brain-dead patients treated with high-dose catecholamine showed significantly decreased KBRs, revealing the detrimental effect of catecholamine on liver metabolism. In contrast, 8 of the 9 untreated patients with blood pressure below 80 mm Hg showed almost normal KBRs. In the 25 donors in Germany, KBR was maintained within the normal range. Based upon conventional criteria, 21 livers were selected for use and the other 4 were discarded. Nineteen of the grafts were able to normalize KBR within 24 h after reperfusion, while 2 failed to function and required a second transplantation. It was suggested that a KBR in the normal range in donors is a prerequisite to immediate recovery of metabolic function of the liver graft after transplantation, and that hypotensive donors as a potential source of liver grafts may warrant further study.

Adolescent↗
PubMed1990

Influence of dopamine on the liver assessed by changes in arterial ketone body ratio in brain-dead dogs.

The influence of dopamine on liver metabolism in the state of brain death was assessed by measuring arterial ketone body ratio (AKBR) in dogs. Mean arterial blood pressure (MABP) was significantly decreased, from 137.4 +/- 3.7 to 64.7 +/- 2.8 mm Hg, 1 hour after completion of brain death (p less than 0.01). In the control group AKBR was maintained at the near control value of 1.07 thereafter, concomitant with a significant decrease in serum lactate levels, despite marked hypotension (p less than 0.05). Dopamine infusion at rates of 5 and 10 micrograms/kg/min sustained both AKBR and MABP at near control values. In contrast, dopamine given at doses greater than 15 micrograms/kg/min caused a significant reduction of AKBR, to less than 0.66 +/- 0.12 (p less than 0.01), although MABP was restored to near-normal levels. In addition, serum levels of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase were significantly elevated, reflecting liver cell injury. It is suggested that the liver is primarily tolerant to hypotension in the state of brain death and that dopamine administered at a rate of 15 micrograms/kg/min or more impairs liver metabolism by reducing the redox state (free nicotinamide-adenine dinucleotide/reduced nicotinamide-adenine dinucleotide) of liver mitochondria.

Animals↗
PubMed1990

Prognostic implications of postoperative suppression of arterial ketone body ratio: time factor involved in the suppression of hepatic mitochondrial oxidation-reduction state.

To determine the tolerance limit of the liver in the critically suppressed mitochondrial oxidation-reduction state, the arterial ketone body ratio (acetoacetate/3-hydroxybutyrate), which reflects hepatic mitochondrial oxidation-reduction potential, was measured 1319 times in 161 patients during the postoperative critical period. Because patients who showed arterial ketone body ratios between 0.40 and 0.25 had a higher incidence of postoperative complications than had those who showed ratios above 0.40, this was designated as the critical zone of the arterial ketone body ratio. When duration in the critical zone was less than 2 days, 90% of the patients were able to tolerate the condition and survive. By contrast, when an arterial ketone body ratio below 0.40 was prolonged for more than 5 days, there was a high incidence of multiple organ failure and a 100% mortality rate, with the average survival period after a 5-day suppression being estimated as 5.7 +/- 2.4 days. It is suggested that the arterial ketone body ratio in the critical zone must be returned to normal values within 2 days to obtain a good prognosis.

Adolescent↗
PubMed1989

[Effects of neo-adjuvant chemotherapy with UFT (a combination of tegafur and uracil) on DNA-synthesizing enzyme activities in human colorectal carcinomas].

Thymidylate synthetase (TS) and thymidine kinase (TK) are known to catalyse the methylation of dUMP for the de novo synthesis of dTMP and the phosphorylation of thymidine for the salvage synthesis of dTMP in the pyrimidine pathway, respectively. High TS and TK activities have been observed in rapidly proliferating tissues such as foetal tissue, regenerating liver and carcinomas. TS and TK activities were measured in histologically normal colon mucosa and colorectal carcinomas with or without neo-adjuvant chemotherapy of an antitumor drug UFT (a combination of tegafur and uracil) in humans. In colorectal carcinomas, 5-FU and uracil levels were increased to 2.6- and 3.2-fold, respectively, those in normal colon mucosa by neo-adjuvant chemotherapy of UFT. In colorectal carcinomas, TS and TK activities were both increased to approximately 2- and 3-fold, respectively, those in normal colon mucosa without UFT treatment. In normal colon mucosa and colorectal carcinomas with neo-adjuvant chemotherapy of UFT, TS activities were reduced to approximately 50% and 40%, respectively, those without UFT treatment. These results indicate that neo-adjuvant chemotherapy with UFT may prevent dissemination of cancer cells during operation, and local recurrence and distant metastasis after operation, inhibiting DNA synthesis via the de novo pathway of pyrimidine synthesis in carcinomas.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Hepatic tolerance to hypotension as assessed by the changes in arterial ketone body ratio in the state of brain death.

Hepatic tolerance to hypotension was assessed by changes in arterial ketone body ratio (KBR) and hepatic energy charge levels in experimental brain death induced by epidural ballooning in dogs, and compared with the hemorrhagic shock model. Systolic arterial blood pressure was significantly decreased from 182 mmHg to 67 mmHg after completion of brain death (P less than 0.01), but KBR was maintained at near the control value of 1.098 +/- 0.051 in spite of marked hypotension. Hepatic energy charge was 0.846 +/- 0.016 and remained at normal level. No significant changes were observed in lactate level, total bilirubin, SGPT, and LDH. SGOT was slightly elevated but was still within normal limits (P less than 0.05). Light microscopic examination revealed no apparent ischemic change in the centrilobular region under hematoxylin and eosin staining. By contrast, KBR decreased from 0.975 +/- 0.054 to 0.273 +/- 0.060 following hypotension in the Wiggers' shock model (P less than 0.01). Lactate levels were gradually elevated significantly (P less than 0.05), but no significant increases were observed in total bilirubin, SGOT, SGPT, and LDH. It is suggested that the hepatic energy status is well maintained in the state of brain death, in which state the liver has high tolerance to marked hypotension until shortly before stoppage of the heart.

Animals↗
PubMed1989

Effects of beta-lactamases and omp mutation on susceptibility to beta-lactam antibiotics in Escherichia coli.

Four types of beta-lactamases consisting of a penicillinase type I (TEM-1), a penicillinase type II (OXA-1), a cephalosporinase of Citrobacter freundii, and a cephalosporinase of Proteus vulgaris were introduced into Escherichia coli MC4100 and its omp mutants, MH1160 (MC4100 ompR1) and MH760 (MC4100 ompR2), by transformation. Effects of the combination of the omp mutations and these beta-lactamases on the susceptibility of E. coli strains were studied with 15 beta-lactam antibiotics including cephalosporins, cephamycins, penicillins, imipenem, and aztreonam. The ompR1 mutant, MH1160, lacks OmpF and OmpC, and it showed reduced susceptibility to 11 of the 15 beta-lactam agents. The reduction in susceptibility to cefoxitin, moxalactam, and flomoxef was much greater than reduction in susceptibility to the other agents. When the ompR1 mutant produced the cephalosporinase of C. freundii, the susceptibility of the mutant to 12 of the 15 beta-lactam antibiotics decreased. The reduction in susceptibility of MH1160 to 10 of the 12 agents affected by the enzyme was two- to fourfold greater than that observed in MC4100. Such a synergistic effect was also observed with the cephalosporinase of P. vulgaris and ompR1 mutation against six cephalosporins, moxalactam, and aztreonam.

Anti-Bacterial Agents↗
PubMed1989

Galactose absorption after oral administration of lactose in neonates.

1. A lactose tolerance test was performed in infants and children. The majority of the infants showed a good response with serum glucose elevations, while there were poor responders among children more than 2 years old. During this test, serum galactose usually was nondetectable, even in the good responders. 2. After simultaneous loading with a constant amount of galactose and varying amounts of glucose in neonates, the degree of elevation of serum galactose levels decreased with increasing amounts of glucose, and loading with equal amounts of galactose and glucose resulted in no elevation of serum galactose levels. 3. In a 6-year-old galactosemic child, serum galactose levels were markedly and continuously elevated after lactose loading. 4. After galactose loading with simultaneous intravenous glucose loading in neonates, elevation of serum galactose was markedly suppressed, as compared with that after galactose loading alone, while it was higher than that after oral loading with the equal doses of galactose and glucose. From the above, the fact that no increase was observed in serum galactose concentration when lactose was loaded orally in neonates is ascribable partially to inhibited absorption of galactose by glucose in the intestine but in the most part to accelerated metabolism of galactose by the glucose absorbed.

Absorption↗
PubMed1989

Structure-activity relationship studies on 4''-O-acyltylosin derivatives: significance of their 23-O-mycinosyl and 4''-O-acyl moieties in antimicrobial activity against macrolide-resistant microbes.

Essential roles for both the 23-O-mycinosyl and 4''-O-acyl moieties of 4''-O-acyltylosin derivatives in the expression of antimicrobial activity against multiple macrolide-resistant strains of Staphylococci and mycoplasmas were demonstrated by in vitro comparison of the MICs of erythromycin, josamycin, tylosin and its 3- and 4''-O-acyl derivatives, demycinosyltylosin (DMT) and its 3- and 4''-O-acyl derivatives and 23-modified 3-O-acetyl-4''-O-isovaleryl-DMT derivatives.

Anti-Bacterial Agents↗
PubMed1989

Tibial plateau-fibular head distance of normal Japanese knees measured in lateral view of roentgenogram.

In total knee arthroplasty, the top of fibular head sometimes has to be resected simultaneously during cutting tibial plateau. Therefore, tibial plateau-fibular head distance was measured in the 244 normal knees of 125 Japanese volunteers (80 men, 45 women), with average age of 27 years ranging from 21 to 40 years. Tibial plateau-fibular head distance was measured using lateral view of knee roentgenogram. The average distance was 6.1 +/- 2.5 mm in men (range, -0.5 to 12.5 mm), and 4.7 +/- 2.6 mm in women (range, -2.5 to 12.0 mm), which was thinner than that of tibial component of conventional knee prosthesis (6-8 mm or over). The relatively high level of fibular head in Japanese may disturb proper positioning of tibial component and transmit load to tibial component in weight bearing, resulting in gradual medial tilting of the tibial component. Resection of either a tip of the fibular head or a segment of the shaft may solve this problem.

Adult↗