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Biomedical subjects

T Machi

Publications and source records attributed to T Machi.

At least 37 records · Page 2Linked to original sources
PubMed1993

Capnocytophaga sputigena bacteremia associated with acute leukemia.

During a three-year period, Capnocytophaga sputigena bacteremia occurred in three patients with acute leukemia receiving induction therapy on a hematology ward. Oral pathology such as periodontitis or severe mucositis was considered to be the most likely source of bacteremia. All three blood culture isolates were identified as that species by deoxyribonucleic acid (DNA) homology studies. Because of the phenotypical similarity of Capnocytophaga species, it is difficult to differentiate them by conventional bacteriological methods. All three isolates were susceptible to antibiotics active against most anaerobes. However, production of beta-lactamase was found in two isolates, one of which proved resistant to both piperacillin and ceftazidime. Therefore, the empiric use of imipenem or clindamycin may be justified in febrile granulocytopenic patients with cancer who develop significant oral lesions.

Acute Disease↗
PubMed1993

[Plasma exchange failures in two patients with thrombotic thrombocytopenic purpura].

We treated two patients with thrombotic thrombocytopenic purpura (TTP) with multiple plasma exchanges for a short period. Following 6 plasma exchanges during 11 days in patient 1 and the 8 exchanges during 13 days in patient 2, consciousness disturbance and thrombocytopenia improved with a decrease in serum lactate dehydrogenase (LDH) levels in both patients. However, thrombocytopenia rapidly progressed with a rise of serum LDH levels after a few days from cessation of the treatment. They received a few rounds of plasma exchange without beneficial effects and eventually died of massive hemorrhage. The clinical course of these patients indicates that some patients with TTP are refractory to repeated plasma exchanges for a short period. It seems important to determine the target point in blood chemistry values such as the LDH level for plasma exchange at which the treatment could be discontinued without causing relapse of TTP.

Aged↗
PubMed1992

Instability of F-actin in the absence of ATP: a small amount of myosin destabilizes F-actin.

The effects of the neutral salt concentration, pH, and coexistence of myosin on the denaturation of F-actin without ATP at low temperature were studied using the DNase I inhibition assay. The percent denaturation of F-actin gradually increased with a decrease in pH from 8.0 to 5.2, on incubation for 2 weeks in the presence of 50 mM KCl at 0 degrees C. This change was much faster in 0.5 M KCl and more than 75% of the F-actin became denatured on incubation for 1 week at pH 5.2. The buffer composition was found to exert a strong influence on the denaturation of F-actin. That is, there was a tendency for the denaturation of F-actin at pH 6.0 to be faster in MES[2-(N-morpholino)ethanesulfonic acid]-NaOH buffer than in sodium phosphate buffer, the critical concentrations of actin in 0.5 M KCl being 0.31 mg/ml for MES-NaOH buffer and 0.15 mg/ml for sodium phosphate buffer. A sigmoidal relationship was found between the percent denaturation of F-actin and the KCl concentration added, the greatest change occurring at KCl concentrations between 0.25 and 0.75 M. The time courses of the denaturation of F-actin showed that the percent denaturation rose at first and that in time the rate of the increase decreased. In the case of pH 8.0 and 0.5 M KCl, it took about 1 week for the denaturation rate to begin to drop. The pH of 6.0 further promoted the instability of F-actin exposed to high KCl concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1992

Changing patterns of blood culture isolates from patients with acute leukemia: a review of twenty years' experience.

During the 20-year period, 1972-1991, 286 episodes of bacteremia occurred in 200 (45%) of 445 patients with acute leukemia in a hematology ward, giving an incidence of 482 episodes per 1,000 hospital admissions. The frequency of bacteremia was almost unchanged throughout the study period. The frequency of gram-negative bacilli decreased significantly, however, from 81% of all the isolates for the first half of the study period to 50% for the latter half. Despite the common use of ceftazidime and imipenem during the last 5-year period, Pseudomonas aeruginosa increased in frequency to be the most frequent organism. This was opposite to the decreased frequencies of Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae. The isolates of P. aeruginosa obtained during this period, all of which proved sensitive to ceftazidime and/or imipenem, were almost equally distributed among five serogroups, although a temporal preponderance of a limited number of serogroups was observed during the preceding 15-year period. On the other hand, the frequency of gram-positive cocci increased from 9% in the first decade to 35% in the latter decade. Staphylococcus epidermidis, Enterococcus species and, to a lesser extent, Staphylococcus aureus were ranked as major pathogens. Among the recent isolates of S. aureus, methicillin-resistant strains virtually replaced methicillin-sensitive ones. Therefore, until more effective means for control of P. aeruginosa bacteremia in particular become available, the occurrence of this infection will continue to limit the successful treatment of acute leukemia.

Acute Disease↗
PubMed1992

Staphylococcus aureus bacteremia in patients with hematologic disorders.

During the 20-year period, 1972-1991, 27 episodes of Staphylococcus aureus bacteremia, including 10 with methicillin-resistant strains (MRSA), were documented in 26 patients with hematologic disorders, mainly acute leukemia and malignant lymphoma, representing 6% of all 433 episodes of bacteremia in a hematology unit. MRSA replaced methicillin-sensitive strains (MSSA) in the last four years. The skin and upper respiratory tract were the two most common primary foci. Most episodes occurred during neutropenia. Pharyngeal colonization often preceded the development of bacteremia. Antibiotic therapy predisposed to MRSA acquisition during hospitalization, whereas MSSA was mostly detected in admission cultures. Among 22 patients with monomicrobial bacteremia, 19 (86%) survived longer than one week, including all four with MRSA bacteremia who received vancomycin. The survival rate did not differ materially between MRSA and MSSA bacteremias. Secondary foci, chiefly located in the lung, were found in 30% of all patients with S. aureus bacteremia. Prolonged antibiotic therapy, therefore, seems warranted in patients with evident metastatic lesions, although abbreviated therapy is proposed in neutropenic cancer patients.

Adolescent↗
PubMed1992

Effect of recombinant human granulocyte colony-stimulating factor (G-CSF) in the treatment of Pseudomonas aeruginosa bacteremia complicating hematologic malignancy--a preliminary study.

The efficacy of recombinant human granulocyte colony-stimulating factor (G-CSF) in the treatment of Pseudomonas aeruginosa bacteremia in cancer patients receiving intensive chemotherapy was studied retrospectively. In 14 of the 24 episodes of P. aeruginosa bacteremia, which occurred in 23 severely neutropenic patients with hematologic malignancies during a three-year period, G-CSF was given subcutaneously or intravenously at daily doses of 75 micrograms/body to 200 micrograms/m2 of body surface. Overall, survival at one week after onset was observed in 13 patients (54%). Treatment with G-CSF, however, had no statistically significant association with one-week survival, although a favorable outcome was well correlated with an increase in the neutrophil count during therapy. On the other hand, septic shock and appropriate antibiotic therapy were the major prognostic factors. The frequency of shock was reduced by appropriate therapy, but not by G-CSF treatment. These preliminary findings thus suggested that G-CSF should not be effective in the treatment of neutropenic cancer patients with P. aeruginosa bacteremia. No adverse effects of G-CSF were observed.

Adolescent↗
PubMed1992

Effect of bilirubin on rabbit cerebral arteries in vivo and in vitro.

The effect of bilirubin on vasoreactivity was examined in the exposed rabbit basilar artery (diameter, 1045 +/- 17 microns; n = 18) and its cortical branches (diameter, 265 +/- 11 microns; n = 43) in vivo. Vasoconstriction induced by uridine triphosphate (UTP; 10(-5) to 10(-3) mol/L) was observed in vivo before and after a 60-minute application of supersaturated bilirubin (10(-4) mol/L). Bilirubin was dissolved in modified artificial cerebrospinal fluid (pH 7.4) or in physiological salt solution (pH 7.6). The latter was spectrophotometrically estimated to contain a higher concentration of free bilirubin because of the formation of less colloid. After treatment with bilirubin in artificial cerebrospinal fluid, the effect was minimal in the basilar arteries (n = 7), whereas the diameter of the branches was reduced by 9.6 +/- 1.5% (n = 23) and UTP-induced vasoconstriction was potentiated. After application of bilirubin in physiological salt solution, the basilar arteries contracted slightly (-2.1 +/- 0.9%; n = 6) and the UTP-induced vasoconstriction in the branches was attenuated (n = 12). After a 60-minute incubation of basilar artery with bilirubin in physiological salt solution in vitro, isometric tension recordings showed a diminution in KCl- and UTP-induced vasoconstrictions. Acetylcholine- and sodium nitroprusside-induced relaxations were also attenuated. It is suggested that bilirubin may exert different effects depending on the size of arteries and the concentration of free bilirubin. The constrictor and potentiating effects of bilirubin could be caused by the impairment of the relaxation mechanism. When the toxic effect of bilirubin becomes severe, the constrictor mechanism is also damaged.

Acetylcholine↗
PubMed1992

The effect of hemoglobin on vasodilatory effect of calcium antagonists in the isolated rabbit basilar artery.

The effect of hemoglobin on the vasodilatory effect of calcium antagonists was studied in isolated rabbit basilar arteries using an isometric tension measurement method. The ability of nimodipine to relax or inhibit contractions elicited by high K+ depolarization or serotonin (5-hydroxytryptamine, 5-HT) was investigated in control arterial rings and rings pretreated by hemoglobin. Hemoglobin (10(-6) and 10(-5) M) reduced the relaxation induced by nimodipine (10(-10) to 10(-8) M) in the rings contracted by 40 mM KCl. This reduction in relaxation was also observed with 3 x 10(-10) to 3 x 10(-9) M nicardipine, 3 x 10(-8) to 3 x 10(-7) M verapamil, and 10(-7) to 10(-6) M diltiazem. On the other hand, the effect of nimodipine was not influenced by endothelial removal or by pretreatment with 10(-5) M albumin or 10(-6) M prostaglandin F2 alpha. Hemoglobin restored the 10(-10) and 10(-9) M nimodipine-induced inhibition of the contraction elicited by CaCl2 (0.3 to 20 mM) in a K(+)-rich, Ca(++)-free solution. This restoration was greater at higher concentrations of CaCl2. Hemoglobin enhanced both the nimodipine-sensitive tonic phase and the less sensitive phasic phase of contractions produced by 10(-6) M of 5-HT. It abolished the inhibitory effect of 10(-8) and 10(-7) M nimodipine on the phasic contraction. Endothelial removal also enhanced both phases of the contraction, but did not abolish the effect of nimodipine. This study showed that the vasodilatory effect of calcium antagonists, especially nimodipine, on the vasoconstriction induced by other vasoactive substances decreased in the presence of hemoglobin.

Albumins↗
PubMed1991

Effect of subarachnoid hemorrhage on serotonin uptake and metabolism in rabbit basilar artery.

The effects of subarachnoid hemorrhage (SAH) on neuronal uptake and metabolism of serotonin (5-HT) in the rabbit basilar artery were examined. Extracted 3H-amines from the isolated arteries after incubation with [3H]5-HT were separated by column chromatography. Radioactivity of 5-HT and 5-hydroxyindoleacetic acid was, respectively, 52.7 +/- 13.9 and 22.9 +/- 5.4 x 10(2) dpm/mg tissue in the control group (n = 8); 32 and 18% of control after denervation (n = 6); 99 and 12% of control after treatment with pargyline (n = 7); and 65 and 76% of control after SAH (n = 7). These results suggest that the neuronal uptake of 5-HT is impaired by SAH, although monoamine oxidase activity is relatively preserved.

Animals↗
PubMed1991

Disseminated mycobacteriosis in patients with severe hematologic disorders.

During a 20-year period disseminated mycobacteriosis occurred in 11 (1.1%) of a total of 1006 patients with severe hematologic disorders, with the frequency remaining almost unchanged. The diagnosis in three patients (27%) was made only at autopsy. Tuberculosis accounted for 64% of all cases. Female preponderance was seen with a male-to-female ratio of 3:8. The major factors associated with dissemination included immunosuppression, weight loss, old age, and diabetes mellitus. Fever was the most common clinical symptom. Chest X-ray abnormalities, hypoproteinemia, liver dysfunction, and hypoxemia were noted in most cases. The prognosis of tuberculosis depended mainly on early diagnosis and treatment, while that for the nontuberculous variety was largely influenced by the underlying disease. Thus, our findings indicated that clinicians must suspect disseminated mycobacteriosis especially in any febrile patient with recent pulmonary pathology on chest X-ray, so that an adequate trial of therapy can be provided.

Adult↗
PubMed1991

Effect of subarachnoid hemorrhage on serotonin uptake and release in the rabbit basilar artery.

This study analyzes the changes induced by subarachnoid hemorrhage (SAH) on the serotonin (5-hydroxytryptamine, 5-HT) uptake and release evoked in rabbit basilar arteries by tyramine. Rabbits were injected with 5 ml of autologous arterial blood into the cisterna magna to produce SAH. Tritium accumulation in basilar arteries was measured after 30 minutes of incubation with 10(-7) M [3H]5-HT and a subsequent 120-minute superfusion (1 ml/min) period. The uptake of 5-HT by arteries 1, 2, 3, and 7 days after SAH was found to be 109%, 69%, 57% (P less than 0.05), and 67% (P less than 0.05) (n = 4, 4, 9, and 6; P less than 0.05) of control (n = 13; 16.8 +/- 1.2 X 10(2) dpm/mg tissue), respectively. The neuronal (cocaine-sensitive) uptake of 5-HT in the arteries 3 days after SAH decreased to approximately 38% of control, whereas the extraneuronal (cocaine-insensitive) uptake of both groups had almost the same absolute value (n = 6 and 6; 4.4 +/- 0.4 and 4.8 +/- 0.4 X 10(2) dpm/mg). Autoradiographic study disclosed that dense clusters of silver grains in the adventitia were not observed after treatment with cocaine (3 X 10(-5) M), although a diffuse distribution of grains was present throughout the vascular wall. The labeled arteries were stimulated by superfusion of tyramine, which is known to replace amines in the sympathetic nerve ending. Tyramine (10(-6) and 10(-4) M)-induced 3H efflux was significantly potentiated by SAH (n = 6) and was suppressed by treatment with cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗