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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 73 records · Page 4Linked to original sources
PubMed2001

Strict closed-system drainage for treating chronic subdural haematoma.

A comparative study chiefly of the recurrence rate of chronic subdural haematoma after two treatment modalities was conducted. Patients were divided into a burr hole strict closed-system drainage group (SCD group; n=56) and a burr hole closed-system drainage with irrigation group (CDI group; n=45). The burr hole strict closed-system drainage involved simply inserting a drainage tube into the haematoma cavity as quickly as possible after minimally incising the haematoma capsule. The introduction of air into the haematoma cavity was prevented, and irrigation was not performed. Symptoms in both groups disappeared soon after surgery, with no postoperative complications. Haematoma recurred in one patient (1.8%) of the SCD group compared with 5 (11.1%) of the CDI group. The rate of recurrence was significantly lower for the SCD than for the CDI group (p<0.05). In 4 of 5 recurrences in the CDI group, the volume of residual intracapsular air was sufficient after initial surgery. These results suggested that postoperative residual intracapsular air is a factor contributing to recurrence. Burr hole strict closed-system drainage is a simple, less invasive procedure with which to treat chronic subdural haematoma and the outcome is excellent. Furthermore, prevention of intracapsular air intrusion during surgery might help prevent recurrence.

Adult↗
PubMed2001

Factor XII but not protein C, protein S, antithrombin III, or factor XIII is a predictor of recurrent miscarriage.

OBJECTIVE: To investigate whether a decrease in the values of protein C (PC), protein S (PS), antithrombin III (ATIII), factor XII (FXII), or factor XIII (FXIII) has predictive value for subsequent miscarriages. DESIGN: Prospective study. SETTING: Nagoya City University Medical School. PATIENT(S): A total of 536 patients with a history of two or more first-trimester miscarriages. INTERVENTION(S): One hundred and twelve patients treated with low-dose aspirin were excluded from the analysis. MAIN OUTCOME MEASURE(S): The subsequent pregnancy outcome of 424 patients was compared for abnormal and normal levels of each parameter. RESULT(S): There were no differences in the subsequent miscarriage rates between abnormal and normal values of PC, PS, ATIII, and FXIII. However, the rate with abnormal FXII is significantly higher than that with normal FXII. CONCLUSION(S): A decrease in FXII (but not in PC, PS, ATIII, or FXIII) predicts subsequent miscarriage in patients with a history of first-trimester recurrent miscarriages.

Abortion, Habitual↗
PubMed2001

Bacterial Infection in the Conjunctiva of Patients with Adenoviral Conjunctivitis.

Purpose: We evaluate the microbiological features of mixed infection in adenovirus-infected conjunctiva.Subjects: Isolation of bacteria was performed in 82 samples of adenoviral conjunctivitis at six eye clinics in Japan.Methods: For microbiological diagnosis, we performed immunochromatography (IC) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for detection and serotyping of adenovirus, and PCR for detection of herpes simplex virus (HSV) and Chlamydia trachomatis antigens out of 82 samples with adenoviral conjunctivitis.Results: Pathogenic bacteria were isolated in 6 samples out of 82. Out of these 6 cases, 5 samples were gram-negative rods and most of them were Flavobacterium meningosepticum (4 samples). Adenovirus type 8 was isolated from all these mixed infection cases. However, HSV-1 and Chlamydia trachomatis were not found.Conclusions: From these results, it is suggested that gram-negative rods, especially F. meningosepticum, are the most common bacteria causing mixed bacterial infection in adenoviral conjunctivitis.

Journal Article↗
PubMed2001

Elevation of plasma free PAI-1 levels as an integrated endothelial response to severe burns.

To clarify the role of plasminogen activator inhibitor type 1 (PAI-1) in postburn hypercoagulation, we assayed the plasma levels of tissue-type plasminogen activator (t-PA) antigen, total PAI-1 antigen, and total t-PA-PAI-1 complex in 15 burned patients. The total body surface area of the burn injury ranged from 30 to 80%. Serial blood samples were collected from 12 to 168 h following the thermal injury. The plasma t-PA level and the free PAI-1 level increased significantly in the immediate postburn period, and the percent increase in the latter over the values in the healthy controls was much greater than that of the former. The ratio of the concentrations of t-PA-PAI-1 complex to free PAI-1 decreased throughout the 7 postburn days. The fact that the decreases in this ratio clearly showed no dissociation of the euglobulin fraction suggests that the postburn hypofibrinolysis occurred as a result of increased synthesis of PAI-1. On the other hand, changes in several parameters of the coagulation or fibrinolysis system and in plasma thrombomodulin showed that postburn hypercoagulability is associated with secondary hyperfibrinolysis with no evidence of vascular endothelial injury. The paradoxical coexistence of postburn hyper- and hypofibrinolysis is a good reflection of the character of PAI-1, which is a biphasic protein that is both a functional protein and an acute phase reactant. Thus, increased synthesis of PAI-1 may not enhance postburn hypercoagulability to create a coagulation-dominant type of disseminated intravascular coagulation severe enough to trigger multiple organ dysfunction syndrome. In conclusion, increased synthesis of PAI-1 in the initial postburn period reflects an integrated endothelial response to burn stress, and because it is a functional protein, the concentration of free PAI-1 antigen may be an important index for predicting secondary consumption coagulopathy.

Adult↗
PubMed2001

Effect of roxithromycin on T lymphocyte proliferation and cytokine production elicited by mite antigen.

Clinical evidence suggests that roxithromycin (RXM) may be an effective additional therapy for bronchial asthma. However, how it interferes with allergic responses is unclear. To investigate the mechanisms of action of RXM, lymphocyte transformation and interferon (IFN)-gamma, interleukin (IL)-4 and IL-5 synthesis associated with Dermatophagoides farinae (Df), mite antigen in patients with bronchial asthma were evaluated in vitro in the presence of RXM. T cell proliferation in Df antigen-stimulated patients' lymphocytes was suppressed by 50-100 microg/ml of RXM. Production of IL-4 and IL-5 was similarly decreased by 1-10 microg/ml RXM, whereas, IFN-gamma production, which was reduced by Df-stimulation alone, was increased by 50 microg/ml RXM. Our results suggest that skewed cytokine profiles of patients with mite antigen-induced bronchial asthma may be corrected with RXM, which may mimic those of patients in remission, who are tolerant of Df antigen.

Adolescent↗
PubMed2001

Functional human IgE specific for Dermatophagoides farinae antigen is produced in SCID mice reconstituted with peripheral mononuclear cells derived from healthy persons and patients with asthma.

BACKGROUND: Whether normal peripheral blood mononuclear cells (PBMCs) transferred to severe combined immunodeficient (SCID) mice produce specific IgE remains unclear. METHODS: Mice received injections of Dermatophagoides farinae antigen (Df)-stimulated PBMCs from healthy persons (IgE RAST score of 0). RESULTS: High titers of Df-specific IgE were detected. The Df-specific IgE activity produced was comparable to or higher than that produced by cells from patients with asthma although the time to maximal production was longer. IgE derived from PMBCs of healthy persons or patients with asthma induced histamine release from cultured human basophils that had been stimulated with Df antigen or an anti-IgE antibody. Treatment of Df-stimulated PBMCs with a high dose, but not a low dose, of interleukin-4 stimulated production of Df-specific IgE by PMBCs from healthy persons or patients with asthma. In contrast, intravenous injection of IFN-gamma into reconstituted SCID mice decreased Df-specific IgE production by PBMCs from patients with asthma. In PMBCs from healthy persons, IgE class-switching may occur later and block the effects of treatment with IFN-gamma. CONCLUSIONS: PBMCs from healthy persons and persons with asthma have clones reactive to allergen and produce functional IgE specific for relevant antigens in mite-sensitive bronchial asthma.

Allergens↗
PubMed2001

Extracellular matrix interacts with soluble CD95L: retention and enhancement of cytotoxicity.

Fas ligand (CD95L) is synthesized both on the cell surface membrane and in a soluble form. Although CD95L contributes to immune privilege in the cornea and testis, the functions of these alternatively processed proteins are not well understood. Some reports suggest that the cytotoxicity of soluble CD95L is insignificant, whereas others show potent responses in vivo, including hepatocyte apoptosis that causes liver failure. We show here that extracellular matrix proteins interact with soluble CD95L and potentiate its pro-apoptotic activity. The cytotoxicity of supernatants from CD95L-expressing cells was increased by incubation on tissue culture plates coated with these matrix proteins; this effect was mediated by trimeric soluble CD95L. With the use of immunoprecipitation, it was found that CD95L binds directly to fibronectin. In addition, immunohistochemical analysis of the cornea revealed that soluble CD95L binds primarily to extracellular matrix. The retention of soluble CD95L on extracellular matrices is likely to play an important role in the development of peripheral tolerance in immune-privileged sites.

Animals↗
PubMed2001

Polyethylenimine-mediated gene transfer into pancreatic tumor dissemination in the murine peritoneal cavity.

Although peritoneal dissemination of cancer cells often occurs at the advanced stages of pancreatic, gastric or ovarian cancers, no effective therapy has been established. Cationic lipid-mediated gene transfer into peritoneal dissemination may offer a prospect of safe therapies, but vector improvements are needed with regard to the efficiency and specificity of the gene transfer. In this study, the intraperitoneal injection of plasmid DNA:polyethylenimine (PEI) complexes into mice was evaluated as a gene delivery system for the peritoneal disseminations. The luciferase and beta-galactosidase genes were used as marker genes. PEI was more efficient than the cationic lipids examined in this study in vivo, and the transgene was preferentially expressed in the tumors. Although PCR analysis showed that the injected DNA was delivered to various organs, the distributed DNA became undetectable by 6 months after the gene transfer. Blood chemistry and histological analysis showed no significant toxicity in the injected mice. This study demonstrated that the intraperitoneal injection of DNA:PEI is a promising delivery method to transduce a gene into disseminated cancer nodules in the peritoneal cavity.

Animals↗
PubMed2001

Calcium phosphate crystal-associated proteins: alpha-2-HS-glycoprotein, prothrombin fragment 1 and osteopontin.

To study the inhibitory effects of calcium phosphate-associated proteins on calcium oxalate crystallization and urinary concentrations of proteins in people who form stones and healthy controls. From 60 L of urine from healthy men, calcium phosphate-associated proteins (alpha-2-HS-glycoprotein, prothrombin fragment 1 and osteopontin) were obtained. The effects of the proteins on calcium oxalate (CaOx) crystallization were studied with a mixed suspension mixed product removal system. To examine urinary concentrations of the proteins, urine samples were collected from 17 healthy subjects and 15 stone formers and analyzed using anion-exchange chromatography and an enzyme immunoassay. Prothrombin fragment 1 (PTF1) and osteopontin (OPN) had strong inhibitory effects on CaOx crystallization, while alpha-2-HS-glycoprotein had a mild inhibitory effect. Urinary concentrations of PTF1 and OPN were lower in stone formers than in healthy controls. Low urinary concentrations of PTF1 and OPN might be one of the reasons for stone formation.

Adult↗
PubMed2001

Chemoradiotherapy followed by surgery for thoracic esophageal cancer potentially or actually involving adjacent organs.

The objective of this study was to evaluate the therapeutic usefulness of chemoradiotherapy (CRT) followed by surgery in patients with clinically T4 (cT4) esophageal cancer involving adjacent organs such as the trachea, main bronchi, and large vessels. Thirty-seven patients with cT4 squamous cell carcinoma of the thoracic esophagus were enrolled in this study. The CRT regimen comprised cisplatin (70 mg/m2) on day 1, 5-fluorouracil (700 mg/m2) on days 1-4 and external irradiation (200 cGy/day, total 30 Gy) on either days 8-26 (sequential schedule, n=15) or days 1-19 (concurrent schedule, n022). Two courses of CRT were given. The results of CRT were complete response in nine patients, partial response in 19, no change in three (minor response in two), and progressive disease in six patients. The median response duration in all responders was 172 days (range: 56-2469, n=19). After CRT, 13 patients received surgery. In 12 of these patients, tumors were completely resected. Histopathologic examination of the resected specimen revealed a discrepancy between clinical response and histopathologic effect. The median duration of survival and the 1-, 2- and 5-year survival rates were 304 days (84-3155), 45%, 35% and 23% in all patients, respectively, 866 days (190-3155), 83%, 83% and 57% in the 13 patients whose tumors were resected, and 187 days (84--2630), 25%, 5% and 5% in the 24 patients whose tumors were not resected. Grade 3 toxicity, especially hematological reactions, was noted in 13.5% (5/37) of the patients. There was one toxicity-related death (sepsis). A good outcome may be obtained with CRT, followed by surgery when feasible. However, CRT can cause toxic reactions, and close monitoring of patients is required.

Aged↗
PubMed2001

Improved survival and ammonia metabolism by intraperitoneal transplantation of microencapsulated hepatocytes in totally hepatectomized rats.

BACKGROUND: We evaluated the effects of intraperitoneal transplantation of microencapsulated hepatocytes in a 3-stage total hepatectomy rat model. METHODS: A new model of total hepatectomy was created as follows. First, the infrahepatic inferior vena cava was ligated just above the right renal vein. Seven days later, the portal vein was ligated and a portacaval shunt was established using a Teflon catheter over a venipuncture needle. Another 7 days later, total hepatectomy was completed by ligating and dividing the suprahepatic inferior vena cava, the hepatic artery, and the bile duct. Next, 4 x 10(7) hepatocytes (4% of the normal liver hepatocyte mass) isolated from male Wistar rats were microencapsulated within a collagen matrix enveloped by a 3-layer membrane of sodium alginate-poly-L-lysine-sodium alginate copolymer. Capsules containing hepatocytes (diameter, 500-800 microm) and empty capsules (control) were transplanted intraperitoneally 4 days before the total hepatectomy. Survival time and selected blood chemistry concentrations after the total hepatectomy were measured. The capsules were also examined histologically with hematoxylin and eosin staining and modified Gmelin's stain for bile pigments. RESULTS: The survival time was greater in the rats given the microencapsulated hepatocytes than in the control rats (17.3 +/- 3 vs 3.7 +/- 0.1 hours; P <.01). The blood ammonia concentrations increased soon after total hepatectomy but remained significantly lower in the rats with microencapsulated hepatocytes (P <.05). The microcapsules contained numerous viable hepatocytes with abundant bile pigments and no lymphocytic infiltration. CONCLUSIONS: Microencapsulated hepatocytes with an ultrathin polymer layer that protects them from inflammatory and lymphocytic reactions may facilitate their ability to function. In this study, 4 x 10(7) hepatocytes significantly prolonged the survival of rats that underwent hepatectomy and supported ammonia metabolism. Further development of this technique may permit its use in patients with hepatic failure.

Ammonia↗
PubMed2001

Isolation of a benzoate-utilizing Pseudomonas strain from soil and production of catechol from benzoate by transpositional mutants.

Pseudomonas sp. Ba-0511 was isolated from soil by enrichment cultivation on a medium containing 6 mg/ml of sodium benzoate. The bacterium could grow on a medium containing 20 mg/ml of sodium benzoate by a successive enrichment culture. One hundred and twelve transpositional mutants of the bacterium produced catechol from benzoate and accumulated it outside of the cells. Among the mutants, strain BA+63 produced a maximal amount of catechol (2.3 mg/ml) from 6 mg/ml of sodium benzoate after growing for 10.5 h. The conversion rate of benzoate to catechol was 50% on a molar basis. The catechol production by the resting cells increased in the presence of glycerol, and the maximal amount of catechol produced from 6 mg/ml of sodium benzoate reached 3.3 mg/ml at the conversion rate of 72% after 5 h of incubation. The resting cells converted m-methylbenzoic acid to 3- and 4-methylcatechol and m-chlorobenzoic acid to 3- and 4-chlorocatechol.

Benzoates↗
PubMed2001

Intravascular ultrasound imaging before and after angioplasty for stenosis of arteriovenous fistulae in haemodialysis patients.

BACKGROUND: Complications of haemodialysis vascular access have emerged as a major cause of patient morbidity. Intravascular ultrasound imaging is a new technical modality providing visualization of the vessel lumen and wall structure in a cross-sectional fashion. Percutaneous transluminal angioplasty has long been used in the treatment of stenoses of arteriovenous fistulae. However, there is no detailed quantitative information on the stenotic lesion and the morphological change by angioplasty. METHODS: Intravascular ultrasound studies were performed in 40 haemodialysis patients with 63 stenoses in arteriovenous fistulae who had percutaneous transluminal angioplasty. The patients were qualitatively and quantitatively evaluated for echogenic patterns and morphological changes before and after angioplasty. RESULTS: Morphological plaque features in stenotic lesions were classified as 37 soft (58%), five hard (8%), 20 mixed (32%), and one calcified sites. Plaque fractures after angioplasty were detected in 45/63 (71%) instances. The lumen cross-sectional area was found to be dilated approximately threefold (from 3.8+/-2.4 to 11.1+/-4.5 mm(2)) and the external elastic membrane cross-sectional area was dilated approximately twofold (from 11.1+/-5.3 to 19.8+/-8.1 mm(2)) after angioplasty. CONCLUSION: These results indicate that intravascular ultrasound allows both qualitative and quantitative assessments of arteriovenous fistulae in haemodialysis patients. The results further suggest that the mechanism of expansion of arteriovenous fistulae stenoses by percutaneous transluminal angioplasty involves stretching of the vessel wall as well as plaque fractures.

Adult↗
PubMed2001

Asn to Lys mutations at three sites which are N-glycosylated in the mammalian protein decrease the aggregation of Escherichia coli-derived erythropoietin.

Erythropoietin (EPO) derived from Escherichia coli is unstable to elevated temperature and tends to aggregate with time, making it unsuitable for high-resolution structure analysis. The mammalian EPO contains about 40% carbohydrate, which makes this protein more stable and less prone to aggregate than non-glycosylated E.coli-derived EPO, but makes it unsuitable for high-resolution analysis owing to its size and flexibility. In an attempt to decrease the aggregation of E.coli-derived EPO, the three asparagine residues at positions 24, 38 and 83 were mutated to lysine residues. In the native protein, these residues are the sites of N-linked glycosylation, which suggests that they should be located on the surface of the protein and should not be involved in interactions in the hydrophobic protein core. Therefore, the substitution of basic amino acids for these neutral asparagine residues is not expected to affect the protein structure, but should increase the isoelectric point of the protein and its net positive charge, decreasing its tendency to aggregate at or below neutral pH due to electrostatic interactions. No apparent alterations in receptor binding, as determined by both cell-surface receptor competition assay and in vitro receptor dimerization experiments, were observed when these mutations were introduced into the EPO sequence. However, this mutant protein displayed a significant increase in stability to heat treatment and to storage, relative to the wild-type molecule. This resulted in a greater number of observable cross peaks in the mutant EPO in 2D NOESY experiments. However, the mutant was similar to the wild-type in stability when urea was used as a denaturant. This indicates that the introduced mutations resulted in a decrease in aggregation with heating or with prolonged incubation at ambient temperature, without changing the conformational stability or the receptor binding affinity of the mutant protein. This approach of placing charged residues at sites where N-glycosylation occurs in vivo could be applied to other systems as well.

Amino Acid Substitution↗
PubMed2001

Stomach cancer-related mortality.

In Japan stomach cancer remains the leading cause of cancer-related mortality. We analysed the annual mortality rate of stomach cancer in relation to age, gender and life expectancy in Japan between 1970 and 1995. The adjusted stomach cancer-related mortality rates decreased from 88.9 in 1970 to 45.4 per 100,000 in 1995 in males and from 46.5 to 18.5 per 100,000 in females. The male-female ratio for stomach cancer-related mortality in all ages was 1.9-2.5 during this 25-year period, and the mortality rate was higher in females than in males at young age. The negative contribution to life expectancy for stomach cancer in males was 0.65 years and 0.42 years in females, which is consistent with a higher mortality rate in males. This negative contribution was 41.8% of total cancer in 1970 and 39.4% in 1995 in males and 34.4% and 16.0%, respectively, in females. Our results demonstrated the need to take into consideration the characteristics of stomach cancer in young women and the effects of ageing when designing programmes aimed at prevention and control of this malignancy.

Adult↗
PubMed2001

Models of sexual selection on a quantitative genetic trait when preference is acquired by sexual imprinting.

The evolution of a quantitative genetic trait under stabilizing viability selection and sexual selection is modeled for a polygynous species in which female mating preferences are acquired by sexual imprinting on the parents and by exposure to the surviving population at large. Stabilizing viability selection acts equally on both sexes in the case of a sexually monomorphic trait and on males only in the case of a dimorphic trait. A genetically fixed sensory or perceptual bias defines the origin of the scale on which the trait is measured, and the possibility is incorporated that female preferences may deviate asymmetrically from the familiar-either toward or away from this origin. When viability selection is strong relative to sexual selection, the models predict that the mean trait value will evolve to the viability optimum. With intermediate ratios of the strength of viability to sexual selection, a stable equilibrium can occur on either side of this viability optimum, depending on the direction of asymmetry in female preferences. When viability selection is relatively weak and certain other conditions are also satisfied, runaway selection is predicted.

Animals↗
PubMed2001

Contribution to promoting cancer epidemiology in Japan and to the activities of the UICC and others in cancer epidemiology and prevention.

On the occasion of being awarding the 5th Nagayo Mataro Prize for contributions to promoting cancer epidemiology and international involvement in the UICC (International Union against Cancer), the Monbusho Overseas Field Research (International Scientific Research)-Special Cancer Study and others, it is my pleasure to give a concise description of activities in which I have played a role. My achievements in administration and management are only a small part of the whole of what has been accomplished in cancer epidemiology and prevention, but I hope that a comprehensive coverage of the projects in which it has been my good fortune to participate may provide orientation and suggest priorities for research in the coming decades. I have taken part in many meetings that stimulated the interest of young scientists and physicians in epidemiology and prevention. It can be said that efficient administration and management are indispensable for modern scientific research in order to promote information collection and exchange. I, therefore, humbly hope that my experience may be illuminating.

Cohort Studies↗