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Biomedical subjects

S Kai

Publications and source records attributed to S Kai.

At least 19 recordsLinked to original sources
PubMed2001

Synthesis and photodynamic activity of a cationic zinc monoazaporphyrin bearing a nitrogen atom at the peripheral position.

A new cationic monoazaporphyrin, zinc 2-aza-8,12,13,17-tetraethyl-2,3,7,18-tetramethylporphyrinium iodide 3 was synthesized. Photodynamic activity of 3 in degradation of 2',3'-isopropylideneguanosine 4 was compared with 2-aza-8,12,13,17-tetraethyl-3,7,18-trimethylporphyrin 1, zinc 2-aza-8,12,13,17-tetraethyl-3,7,18-trimethylporphyrin 2, and hematoporphyrin 5. The quarternary ammonium 3 showed a remarkable increase of photodynamic activity compared with 5, although no appreciable difference in the activity was observed between 1 and 5.

Aza Compounds↗
PubMed2000

Nonsteady condensation and evaporation waves

We study the motion of a phase transition (PT) front at a constant temperature between stable and metastable states in fluids with the van der Waals equation of state. We focus on a case of relatively large metastability and low viscosity, when no steadily moving PT front exists. Simulating the one-dimensional hydrodynamic equations, we find that the PT front generates acoustic shocks in forward and backward directions. Through this mechanism, the nonsteady PT front drops its velocity and eventually stops. The shock wave may shuttle between the PT front and the system's edge, rarefaction waves appearing in the shuttle process. If the viscosity is below a certain threshold, a turbulent state sets in.

Journal Article↗
PubMed2000

Radiographic diagnosis of early colorectal cancer, with special reference to the superficial type of invasive carcinoma.

The possibility of radiographically diagnosing carcinoma with submucosal involvement (invasive carcinoma) is discussed based on 119 invasive carcinomas of the large bowel that had been treated surgically and colonoscopically over a period of 9 years (1989-1997) at the Cancer Institute Hospital in Tokyo. Of these lesions, 38 were superficial-type invasive carcinoma, accounting for 31.9% (38/119) of all invasive colorectal carcinomas, including 36 lesions (94.7%, 36/38) of types IIa and IIa + IIc and 2 lesions (5.3%, 2/38) of type IIc + IIa. No pure type IIc was seen. The radiographic images obtained were correlated with macroscopic findings and analyzed in terms of visualization of the lesion's contour, central depression, converging folds, and basal indentation. A definitive diagnosis of superficial invasive carcinoma can be made radiographically if a lesion measures 10 mm and reveals moderate to severe basal indentation in a complete or nearly complete profile radiographic image. Attention should be paid to the presence of superficial-type advanced carcinomas measuring 10 mm or less, which is not infrequently experienced in Japan. Polypoid invasive carcinoma can be definitively diagnosed in the same way with much more certainty than can the superficial type because few polypoid advanced carcinomas are less than 20 mm. The size and the radiographic sign of the basal indentation are the most important indicators for the diagnosis of invasive carcinoma.

Adenoma↗
PubMed2000

Bromomalonic-acid-induced transition from trigger wave to big wave in the Belousov-Zhabotinsky reaction

The Marangoni effects on chemical waves in the ferroin-catalyzed Belousov-Zhabotinsky reaction were studied. The main purpose of the present study was to understand the mechanism of the big wave, an accelerative chemical wave involving surface-tension-driven fluid motions. Spatiotemporal variations of surface tension caused by a chemical wave were measured using the Wilhelmy method. The transition from conventional trigger waves to big waves, due to a concentration change of bromomalonic acid, was observed. The strong surface activity of the bromomalonic acid which was responsible for the transition was also observed. It led to an acceleration of the big waves through the Marangoni effect.

Journal Article↗
PubMed2000

Effects of short-term denervation and subsequent reinnervation on motor endplates and the soleus muscle in the rat.

The rat sciatic nerve was locally frozen, and changes in the nerve, motor endplates, and the soleus muscle were examined for up to 6 weeks by light and electron microscopy. The wet weights of denervated soleus muscles compared with contralateral values progressively declined to a minimum at 2 weeks after injury (60.7 +/- 2.5%) and began to reverse following 3 weeks. The sciatic nerve thoroughly degenerated after freezing. However, numerous regenerated myelinated and thin nerve fibers were observed at 3 weeks. They were considerably enlarged but still smaller than normal counterparts at 6 weeks postoperatively. Nerve terminals containing synaptic vesicles of endplates disappeared at day 1 and mostly reappeared at 3 weeks (about 70% of the endplates). All endplates examined were reinnervated at 4, 5, and 6 weeks. On the other hand, postsynaptic folds of muscle fibers seemed to be only slightly influenced by denervation or reinnervation. Ultrastructural alterations of myofibrils, in particular the loss of register, immediately appeared after denervation, spread progressively, peaked at 2 weeks, ameliorated following reinnervation, and became significantly normalized at 6 weeks after freezing. The proportion of type II fibers in the soleus muscle similary showed an increase and a decrease with a short delay in response to denervation and reinnervation, respectively. This study clearly demonstrated that the nerve supply affects the ultrastructural integrity of skeletal muscles. In addition, changes in the endplates and the soleus muscle evaluated in this study after short-term denervation are largely reversible following reinnervation.

Animals↗
PubMed1999

Pentachlorophenol (PCP) produces liver oxidative stress and promotes but does not initiate hepatocarcinogenesis in B6C3F1 mice.

To elucidate the mechanism of hepatocarcinogenesis of pentachlorophenol (PCP) in mice, critical effects related to carcinogenicity were studied in the livers of B6C3F1 male mice administered PCP at concentrations of 600 and 1200 p.p.m. in the diet for 8 weeks. Oxidative stress was assessed by measurements of 8-oxodeoxyguanosine (8-oxodG) in the liver nuclear DNA and hepatocyte cell proliferation was quantified by bromodeoxyuridine incorporation. Also, initiation and promotion were assessed in a two-stage hepatocarcinogenesis model in which one group of mice was given PCP at concentrations of 600 and 1200 p.p.m. as initiator for the first 13 weeks with subsequent administration of phenobarbital (PB) as promoter at a concentration of 500 p.p.m. in the drinking water for 29 weeks. A second group was initiated with diethylnitrosamine (DEN) at 20 p.p.m. in the drinking water for the first 13 weeks followed after a 4 week recovery interval by PCP at concentrations of 300 and 600 p.p.m. in the diet for 25 weeks. Significant elevations in 8-oxodG levels and cell proliferation were observed in a dose-dependent manner. Incidences and multiplicities of hepatocellular tumors in mice treated with PCP after DEN initiation were increased compared with those in mice given initiation only. In contrast, in mice given PCP as initiator followed by PB no enhancement of neoplastic lesions occurred. These findings are interpreted to demonstrate that PCP exerts a promoting action, but not an initiating effect on liver carcinogenesis and that the promoting action is related to oxidative stress and compensatory hepatocellular proliferation.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Tumor markers CEA, CA19-9 and CA125 in monitoring of response to systemic chemotherapy in patients with advanced gastric cancer.

BACKGROUND: To evaluate whether tumor markers can be used to assess response to systemic chemotherapy, we analyzed preliminarily the relationship between the response to chemotherapy based on serial imaging and on change in serum tumor marker level of CEA, CA19-9 and CA125. METHODS: We analyzed 26 patients with advanced gastric cancer in whom at least one of the tumor markers CEA, CA19-9 and CA125 was elevated before systemic chemotherapy with regard to the relationship between the change in serum tumor marker level and response assessment by imaging studies throughout the treatment course. A responder was defined as showing a > or = 50% drop in tumor marker level for more than 4 weeks. RESULTS: The sensitivity and negative predictive value of falling tumor marker level after chemotherapy for a partial response in imaging was 100%. When patients were categorized as responders or non-responders, a significant correlation was observed between the assessment of response by tumor markers and by imaging studies. The survival time of responders assessed by tumor markers was significantly longer than that of non-responders. CONCLUSIONS: The measurement of tumor markers might be useful in monitoring response and in predicting the prognosis of patients with advanced gastric cancer treated with systemic chemotherapy. Tumor markers may be used as a means of monitoring treatment in patients when in an imaging study it is difficult to assess response to chemotherapy in clinical practice. Further studies are required to confirm these findings.

Adult↗
PubMed1999

[Cord blood transplantation for adults].

Current reports from Europe and USA show that unrelated cord blood transplantation (CBT) gives good results in treating with children with malignancies and other disorders. However, there are not enough patients in the adults to perform a comparison with other stem cell transplantations. In unrelated CBT, HLA disparity is not a limiting factor and the incidence and the severity of acute and chronic GVHD is lower, even in the state of HLA 2 or 3 antigen-mismatched transplant, than in other stem cell transplantation, but the number of cells infused is important. At this stage, unrelated CBT is an optional source of stem cells in adults patients with malignancies who lack HLA compatible donors in bone marrow donor registries. However, the choice of cord blood units containing large number of cells and good disease status at transplantation might improve results.

Adolescent↗
PubMed1999

[A patient with hepatic metastasis of breast cancer successfully treated with combined chemoendocrine therapy using epirubicin, tegafur and tamoxifen].

A solitary 1 cm sized metastatic lesion was found in the S5 region of the liver on a postoperative ultrasound screening of a 52-year-old breast cancer patient. It was confirmed by CT, MRI and hepatic angiography. At first, she was successfully treated with trans-arterial pirarubicin and lipiodol infusion but a metastatic lesion of similar size was found 6 months later in the same region. We then administered a triple 20 mg dose of epirubicin intravenously, and 450 mg of UFT and 30 mg of tamoxifen daily. Six months later the lesion had disappeared on US and CT scans and a complete remission has persisted for 18 months.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

[Fundamental and clinical study of three-dimensional compensating filters and direct dose monitoring system for total body irradiation].

We devised 3D-compensating filters to improve dose distribution during total body irradiation (TBI). This study investigated the effect of these 3D-compensating filters and related complications in patients who had undergone bone marrow transplantation (BMT) followed by TBI. The 3D-compensating filters were fabricated by CT measurement of body thickness. The effectiveness of the 3D-compensating filters in producing a homogeneous dose distribution was checked by a thermoluminescent dosimeter (TLD) and semiconductor detectors in all patients. At the pelvis, the dose was measured simultaneously with an ionization chamber. The average dose distribution to each site when the 3D-compensating filter was used was 93% to the head, 97% to the neck, 99% to the thorax, and 98% to the pelvis in TLD when the scheduled dose was taken as 100%. There was no significant difference between the TBI and non-TBI groups with regard to the frequency of lung toxicity. Clinical interstitial pneumonitis occurred in 22.7% of the patients, interstitial pneumonitis with CMV in 13.6%, and idiopathic pneumonitis in 6.1% without any virus infection. Only one patient was regarded as having radiation-induced pneumonitis. 3D-compensating filters can be conveniently produced within a short time following CT measurement, and they seem to be safe and useful for dose flattening during TBI.

Adolescent↗
PubMed1998

Evidence that CD31, CD49b, and CD62L are immunodominant minor histocompatibility antigens in HLA identical sibling bone marrow transplants.

Despite complete matching of siblings for the HLA loci, after bone marrow transplantation (BMT), approximately 20% develop graft-versus-host disease (GVHD). This is presumably due to incompatibility of minor histocompatibility antigens (mHa). We investigated the polymorphisms of 14 adhesion molecules (CD2, CD28, CD31, CD34, CD36, CD42, CD44, CD48, CD49b, CD54, CD62L, CD86, CD102, and CD106) in Japanese subjects and their association with the occurrence of GVHD after allogeneic HLA identical BMT. Six molecules (CD2, CD31, CD42, CD49b, CD54, and CD62L), which were found to be polymorphic, were then examined in 118 HLA identical sibling donors and recipients who had undergone BMT. Association of the incompatibility of the polymorphic molecules with the presence or absence of GVHD was examined. In these six, we observed a significant correlation between acute GVHD and the compatibility of CD31 (codons 563/670) (Pcorrected = .018), and CD31 (codons 563/670) + CD62L (Pcorrected = .018) in patients with the HLA-B44-like superfamily. In patients with the HLA-A3-like superfamily, the compatibility of CD62L (Pcorrected = .03) and CD62L + CD49b (P = . 004, Pcorrected = .078) was associated with acute GVHD. Therefore, CD31, CD49b, and CD62L might be candidates for immunodominant mHa.

Adolescent↗
PubMed1998

Protective effects of green tea on hepatotoxicity, oxidative DNA damage and cell proliferation in the rat liver induced by repeated oral administration of 2-nitropropane.

To evaluate the benefit of green tea in mitigating hazards caused by repeated exposure of 2-nitropropane (2NP), we examined the effects of the tea on toxic indices, oxidative DNA damage and cell proliferation in the liver of 2NP-treated rats. Male Fischer 344 rats were administered, by gastric intubation, a total of six doses of 60 mg/kg 2NP(L), or alternatively two doses of 90 mg/kg and then four doses of 120 mg/kg 2NP(H) during 2 weeks. Green tea infusion was given to the rats as drinking water 1 week before the 2NP treatments and throughout the experiment. Significant elevation of hepatotoxic indices was evident in the 2NP(H)-treated group, such as an increase of serum glutamic-oxaloacetic transaminase (GOT) activity and of hepatic lipid peroxidation, together with a decrease in hepatic glycogen and serum triglyceride, and degenerative changes in the hepatocytes. A dose-related increase was observed in oxidative DNA damage and cell proliferation in the liver. Green tea effectively inhibited all of above changes induced by 2NP treatment, suggesting that tea intake may be effective for preventing the hepatic injuries after chronic exposure to 2NP.

Animals↗
PubMed1998

Loss of heterozygosity of NF1 gene in juvenile chronic myelogenous leukemia with neurofibromatosis type 1.

To investigate a genetic relation between juvenile chronic myelogenous leukemia (JCML) and neurofibromatosis type 1 (NF-1), we analyzed the NF1 gene in the leukemic cells of a JCML patient with NF-1. We found a point mutation in exon 29 of one allele and a deletion of the other normal allele in the leukemic cells. The point mutation is considered a germline mutation because it was also detected in fibroblasts obtained from the bone marrow of the patient and the peripheral blood mononuclear cells from a sibling. A loss of heterozygosity of NF1 gene may contribute to the progression of leukemia in NF-1 patients.

Alleles↗