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Biomedical subjects

T Arakaki

Publications and source records attributed to T Arakaki.

At least 19 recordsLinked to original sources
PubMed2002

Variation in CO2 assimilation rate induced by simulated dew waters with different sources of hydroxyl radical (*OH) on the needle surfaces of Japanese red pine (Pinus densifora Sieb. et Zucc.).

The hydroxyl radical (*OH) is generated in polluted dew on the needle surfaces of Japanese red pine (Pinus densiflora Sieb. et Zucc.). This free radical, which is a potent oxidant, is assumed to be a cause of ecophysiological disorders of declining trees on the urban-facing side of Mt. Gokurakuji, western Japan. Mists of *OH-generating N(III) (HNO2 and NO2-) and HOOH + Fe + oxalate solutions (50 and 100 microM, pH 5.1-5.4) simulating the dew water were applied to the foliage of pine seedlings grown in open-top chambers in the early morning. Needles treated with 100 microM N(III) tended to have a greater maximum CO2 assimilation rate (Amax), a greater stomatal conductance (g(s)) and a greater needle nitrogen content (Nneedle), suggesting that N(III) mist acts as a fertilizer rather than as a phytotoxin. On the other hand, needles treated with 100 microM HOOH + Fe + oxalate solution showed the smallest Amax, g(s), and Nneedle, suggesting that the combination of HOOH + Fe + oxalate caused a decrease in needle productivity. The effects of HOOH + Fe + oxalate mist on pine needles were very similar to the symptoms of declining trees at Mt. Gokurakuji.

Carbon Dioxide↗
PubMed1996

A structure-based model for cytochrome P450cam-putidaredoxin interactions.

Putidaredoxin (Pdx) is a Fe2S2 ferredoxin which acts as the physiological reductant of cytochrome P-450cam (CYP101). A model for the solution structure of oxidized Pdx has been determined using NMR methods (Pochapsky et al (1994) Biochemistry 33, 6424-6432). 1H-15N correlations and redox-dependent amide exchange rates have also been described (Lyons et al (1996) Protein Sci 5, 627-639). Data obtained from mutagenesis and kinetic measurements concerning the interactions of Pdx and CYP101 are summarized. A model for the structure of the homologous ferredoxin adrenodoxin (Adx) is also described, and data concerning Adx activity are discussed in relation to this structure. The structures of Pdx and CYP101 were used as starting points for molecular modeling and molecular dynamics simulations. Close approach between the metal centers of the two proteins and interaction between aromatic residues on the surfaces of the proteins are premised. The resulting complex exhibits three intermolecular salt bridges, five intermolecular hydrogen bonds and a 12 A distance between the metal centers. The first direct observations of interaction between Pdx and CYP101 (by two-dimensional NMR of 15N-labeled Pdx in solution with CYP101) are described. The results of the NMR experiments indicate that conformational gating of the electron transfer complex between CYP101 and Pdx may be important.

Adrenodoxin↗
PubMed1994

[Hypopituitarism caused by colonic carcinoma metastasis associated with hypophysial aspergillosis].

Pituitary metastases constitute 1% to 8.3% of all metastatic brain tumors. The most frequent localization is in the posterior lobe and diabetes insipidus may be the only symptom of dysfunction. Cerebral aspergillosis is an unusual disease and it has been described complicating an underlying malignancy or following intracraneal surgery. We describe a case of hypopituitarism and hyperprolactinemia in a patient with pituitary metastases of a colon carcinoma and aspergillosis. Two years before a colon adenocarcinoma (Class C1 of Duke) had been resected. There were no clinical signs of hypopituitarism or galactorrea. The laboratory findings showed deficiency of cortocotropin (ACTH), luteinizing hormone (LH), follicle stimulating hormone (FSH) and slight hyperprolactinemia (PRL). Cerebral magnetic resonance image (MRI) revealed an intra and suprasellar mass which extended to the hypothalamus. Chest X-ray film and computed tomographic scanning (TC) confirmed a macronodular mass at the apical segment of the inferior left lung lobule with mediastinal hypertrophic lymph nodes. A non functional pituitary tumor was diagnosed and transphenoidal surgery was carried out. At microscopic examination a malignant proliferation was found suggesting colonic differentiation. Fragments of tumoral pituitary tissue showed hyphae of aspergillus in the form of abscess. Aspergillosis complicating neoplastic disease is more often present in leukemia and lymphoma than in solid tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1993

Aqueous-phase photochemical formation of peroxides in authentic cloud and fog waters.

Gas-to-drop partitioning of hydrogen peroxide and its precursor, the hydroperoxyl radical (HO2.), has been considered the predominant or sole source of hydrogen peroxide in atmospheric water drops. However, atmospheric water can absorb solar ultraviolet radiation, which initiates the photoformation of peroxides (primarily hydrogen peroxide). Measurements of peroxide photoformation rates in authentic atmospheric water samples demonstrate that aqueous-phase photochemical reactions are a significant, and in some cases dominant, source of hydrogen peroxide to cloud and fog drops. This additional source could significantly change the current understanding, and hence, the models, of sulfuric acid deposition because hydrogen peroxide is the limiting reagent in the dominant pathway for the oxidation of sulfur dioxide to sulfuric acid in the troposphere over eastern North America.

Atmosphere↗
PubMed1992

Efficacy of ivermectin against Strongyloides stercoralis in humans.

Okinawa Prefecture is an endemic area of Strongyloides stercoralis infection. Since treatment of this infection remains unsatisfactory, we evaluated the efficacy of ivermectin. Twenty-three patients were treated with a single oral dose of ivermectin (mean +/- SD, 105.5 +/- 20.8 mcg/kg of body weight), followed by a second dose two weeks later. The rate of cure was 85.7% at 2 weeks after the first treatment, and 90.5% at 2 weeks after the second treatment. Side effects occurred in 2 patients (8.7%), but they were mild and transient. The results indicate that ivermectin might be useful and relatively safe for the therapy of Strongyloides stercoralis infection as an alternative to thiabendazole or mebendazole.

Aged↗
PubMed1992

Age-related prevalence of Strongyloides stercoralis infection in Okinawa, Japan.

Age-prevalence of Strongyloides stercoralis infection was studied in six areas of Okinawa, Japan. In all localities, most of the infected inhabitants were aged over 40 years of age and females were less infected than males. The peak prevalence was found in inhabitants in their fifties in high endemic groups and shifted to higher age in lower endemic groups. This age-prevalence pattern resembles more that of schistosome infections than that of other gastrointestinal helminthic infections.

Adolescent↗
PubMed1992

Is the prevalence of HTLV-1 infection higher in Strongyloides carriers than in non-carriers?

To assess the concomitance of strongyloidiasis and HTLV-1 infection, an epidemiological survey was conducted in Okinawa, Japan, using the agar-plate culture, a highly sensitive method for detection of Strongyloides stercoralis. No significant difference in the positive rate of anti-HTLV-1 antibody was found between Strongyloides carriers and non-carriers. This result suggests that these two infections occur independently.

Adolescent↗
PubMed1992

Epidemiological aspects of Strongyloides stercoralis infection in Okinawa, Japan.

The epidemiology of Strongyloides stercoralis infection was compared among three localities with various prevalences of human T lymphotropic virus type 1 (HTLV-1) infection in Okinawa Prefecture, Japan, using agar-plate culture of faeces. The prevalence of S. stercoralis infection is much higher in Gusukube, where HTLV-1 infection is rare, than in Yomitan, where this viral infection is common. In all localities the parasite prevalence is significantly higher in males than in females, whereas the prevalence of HTLV-1 infection is much higher in females. These epidemiological facts suggest that infection by S. stercoralis occurs independently of that by HTLV-1.

Adolescent↗
PubMed1991

[Clinical study on ivermectin against Strongyloides stercoralis].

We previously reported the efficacy of ivermectin (IVM) for the treatment of 23 strongyloidiasis patients. We now reported the efficacy and safety of IVM therapy on 54 patients. Fifty-four patients, 28 males and 26 females, received a single oral dose of IVM one hour before breakfast and this treatment was repeated 2 weeks later. The following results were obtained: 1) The cure rate at 2 weeks after the initial treatment was 92.5% (49 of 53 patients) and 2 weeks after the second course was 96.0% (48 of 50 patients). 2) Four patients (7.4%) complained of diarrhea (n = 2 patients), constipation (n = 1), borborygmus (n = 1), dizziness (n = 1), diplopia (n = 1) and peri-anal itching (n = 1) after the first treatment. Three patients (5.6%) complained of borborygmus (n = 1), itching (n = 1) and exanthema (n = 1) after the second treatment. But all symptoms were mild and required no treatment and subsided in a few days. 3) Positive rate of HTLV-1 antibody was 25.9% in the patients. As described above, although side effects occurred in some cases, they were mild and transient. From these results, we concluded that IVM is an effective drug for strongyloidiasis.

Adult↗
PubMed1991

[New trial with thiabendazole for treatment of human strongyloidiasis].

Okinawa prefecture is well known as an endemic area of Strongyloides stercoralis infection, and its recent infection rate was reported 6.2%, which was investigated by a new technique to detect S. stercoralis, agar plate method. Traditional treatment with thiabendazole was temporarily effective for S. stercoralis, but the recurrence rate was extremely high. We tried the new treatment for the purpose of complete eradication of the parasite. The patients were divided into two groups, who were given 500 mg of thiabendazole three times daily for 5 days and not medicated for the following 9 days. The medication was repeated 3 times in group 1 which consisted of 92 patients and 4 times in group 2 which consisted of 70 patients. Obtained results were as follows: 1) Six months after treatment, the cure rate was 89.5% in the only one course treatment, and 100% in more than 2 course treatments. 2) Side effects such as nausea, vomiting, anorexia or general fatigue were noted in 67.5% of all the patients after initial treatment, and 45.1% of the patients were dropped out of this trial. The dose of the drug was reduced in 32.1% of the patients, and only 22.8% were treated with full course of the regimen. 3) The elevation of S-GPT was observed in 33.8% of all patients. After initial treatment the rate was only 8.1%, but after 3 or 4 repeated course of treatments the rate was elevated to 39.0% and 45.4%, respectively. The liver injury was closely related to the total dose of thiabendazole and the period of the medication.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Two case reports of septic shock due to Vibrio vulnificus with liver cirrhosis].

We have recently experienced a case of Vibrio vulnificus septicemia which occurred in a patient with hepatic cirrhosis, and as we were able to give early antibiotic treatment, the patient survived. We would like to report this case here together with another case experienced 2 years ago. Case 1 was a 58-year-old male who was attending our hospital as an outpatient for hepatic cirrhosis. At 5:30 pm on August 8, 1987, he consumed abalone and giant clam and at 9 pm complained of high fever with shaking chills. He was admitted to our department as an emergency case. Cefoperazone was administered resulting in a decline of fever on the following day. During the course of treatment he fell transiently into pre-DIC, but due mainly to the administration of antibiotics his condition was subsided. Case 2 was a 53-year-old male who was under medical care in our hospital for grave hepatic cirrhosis. On October 11, 1985, he consumed sushi and two days later suffered chills and pyrexia. A blood culture revealed Vibrio vulnificus. His condition improved transiently with administration of Cefazolin, but oliguria, hypotension and ascites occurred subsequently, and finally the patient died on the 22nd day.

Humans↗