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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 37 records · Page 2Linked to original sources
PubMed2001

Oxyhemoglobin produces apoptosis and necrosis in cultured smooth muscle cells.

Confluent rat aortic smooth muscle cells were treated with OxyHb in a concentration- and time-dependent manner. A high concentration of OxyHb (100 microM) within 24 h decreased cell density. DNA analysis showed a smear pattern characteristic of cell necrosis. Transmission electron microscopy demonstrated disintegration of the cell membrane and destruction of cell organelles. Western blotting using PARP antibody revealed that 116 kDa PARP was not cleaved to 85 kDa, an apoptosis-related fragment. On the contrary, a low concentration of OxyHb (10 microM) produced apoptotic cell death at 72 h that was supported by DNA analysis and TUNEL staining. These results demonstrated that a high level of OxyHb induced necrosis within 24 h and a low concentration of OxyHb produced apoptosis after 72 h in cultured smooth muscle cells. Morphological alterations induced by OxyHb might contribute to the vascular wall changes in the cerebral arteries following subarachnoid hemorrhage (SAH).

Animals↗
PubMed2001

Suppression of colorectal cancer growth using an adenovirus vector expressing an antisense K-ras RNA.

In human colorectal cancer, K-ras point mutations occur in approximately 40-50% of the cases, a frequency second only to pancreatic cancer (80-90%). Unlike pancreatic and lung cancers, however, the tumor-suppressive effect of antisense K-ras RNA expression has not been examined for colorectal cancers. A recombinant adenovirus vector expressing an antisense or sense K-ras gene fragment (AxCA-AS-K-ras or AxCA-S-K-ras) was first transduced into seven human colorectal cancer cell lines. Stable expression of antisense or sense K-ras RNA was detected by RNA blot analysis. Western blot analysis confirmed a reduction of up to 25% of K-ras-specific p21 protein in the antisense K-ras-transduced HCT-15 cells. In contrast to our previous findings on pancreatic cancer, the status of K-ras point mutations was not correlated with the growth-suppressive effect of the antisense K-ras vector: both the K-ras-mutation-positive and -negative colorectal cancer cell lines were suppressed for their growth in vitro. There was no growth-inhibitory effect on normal cells such as hepatocytes. Next, to test the efficacy in vivo, HCT-15 cells were inoculated subcutaneously into the left flank of SCID mice, and AxCA-AS-K-ras was injected intratumorally three times after the tumor mass was established. The infection of AxCA-AS-K-ras, but not the control AxCA-S-K-ras, significantly suppressed the growth of the HCT-15 subcutaneous tumor. This study shows that the adenovirus-mediated in vivo gene transfer of the antisense K-ras construct may be a useful therapeutic strategy for colorectal cancer.

Adenoviridae↗
PubMed2001

Coexpression of guanylate kinase with thymidine kinase enhances prodrug cell killing in vitro and suppresses vascular smooth muscle cell proliferation in vivo.

Herpes simplex virus-thymidine kinase (HSV-TK) phosphorylates the prodrugs ganciclovir (GCV) and acyclovir (ACV), leading to disruption of DNA synthesis and inhibition of cell proliferation. HSV-TK vectors have been successfully employed in cardiovascular and cancer gene therapy. Activation of GCV and ACV, after an initial phosphorylation step by the viral thymidine kinase, is carried out by guanylate kinase. We reasoned that coexpression of guanylate kinase (GK) with HSV-TK would augment phosphorylation of GCV or ACV, leading to increased cell killing. To test this hypothesis, a vector expressing TK with GK (TKciteGK) was developed and tested on vascular smooth muscle cells (vsmcs) in vitro and in vivo. Compared to HSV-TK vectors, killing of vascular cells transduced with TKciteGK and exposed to GCV was significantly increased (P = 0.03). The TKciteGK construct was evaluated with three promoters: CMV, EF1alpha, and SM22alpha. TKciteGK expression driven by a CMV promoter induced cell killing more effectively than SM22alpha or EF1alpha promoters in primary vsmcs. Based upon these in vitro findings, TKciteGK vectors with a CMV promoter were tested in two animal models of cardiovascular disease: balloon angioplasty and stent deployment in pig arteries. Following vascular injury, expression of CMV-TKciteGK with GCV significantly reduced vsmc proliferation and intimal lesion formation compared to control vectors with GCV. In the angioplasty model, there was an 80% reduction in intima-to-media area ratio (P = 0.0002). These findings were paralleled in a stent model with 66% reduction in intimal lesions (P = 0.006). Coexpression of GK with TK increases cell killing and permits administration of GCV at lower doses. These modifications in TKciteGK vectors and GCV showed enhanced efficacy at lower prodrug doses, leading to improved safety for cardiovascular gene therapy.

3T3 Cells↗
PubMed2001

Theoretical and empirical aspects of gene-culture coevolution.

Cultural transmission can be roughly defined as the transfer of information between individuals by social learning (see below). Genes used to be, and for most species still are, the only means available for the accurate transfer of information across generations. In species where cultural transmission has developed, notably the human, interactions can occur between the two inheritance systems. Gene-culture coevolution refers to the evolutionary phenomena that arise from these interactions. As we shall see, these interactions can take various forms.

Adult↗
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↗