Search PubMed⌕ Search

Biomedical subjects

R Mizuno

Publications and source records attributed to R Mizuno.

At least 55 records · Page 3Linked to original sources
PubMed1998

Anorexia nervosa with left atrial failure.

A 14-year-old girl with anorexia nervosa was admitted to our hospital because of severe weight loss. She was 152 cm in height and weighed 27 kg. An echocardiogram demonstrated normal left ventricular contraction and a small left ventricular end-diastolic dimension. Pulsed Doppler transmitral flow demonstrated normal early filling velocities but a complete absence of late diastolic flow after the apparent electrocardiographic P wave, consistent with atrial electromechanical dissociation, so called atrial failure. Six months after admission, her body weight increased to 42 kg. Pulsed Doppler showed a normal transmitral flow pattern in both early and late diastole. We do speculate that atrial failure was related to malnutrition due to anorexia nervosa. Atrial failure can be one of the clinical features of patients with anorexia nervosa.

Adolescent↗
PubMed1998

Behavior and reproduction of invertebrate animals during and after a long-term microgravity: space experiments using an Autonomous Biological System (ABS).

Aquatic invertebrate animals such as Amphipods, Gastropods (pond snails), Ostracods and Daphnia (water flea) were placed in water-filled cylindrical vessels together with water plant (hornwort). The vessels were sealed completely and illuminated with a fluorescent lamp to activate the photosynthesis of the plant for providing oxygen within the vessels. Such ecosystem vessels, specially termed as Autonomous Biological System or ABS units, were exposed to microgravity conditions, and the behavior of the animals and their reproduction capacity were studied. Three space experiments were carried out. The first experiment used a Space shuttle only and it was a 10-day flight. The other two space experiments were carried out in the Space station Mir (Shuttle/Mir mission), and the flight units had been kept in microgravity for 4 months. Daphnia produced their offspring during a 10-day Shuttle flight. In the first Mir experiment, no Daphnia were detected when recovered to the ground. However, they were alive in the second Mir experiment. Daphnia were the most fragile species among the invertebrate animals employed in the present experiments. All the animals, i.e., Amphipods, pond snails, Ostracods and Daphnia had survived for 4 months in space, i.e., they had produced their offspring or repeated their life-cycles under microgravity. For the two Mir experiments, in both the flight and ground control ecosystem units, an inverse relationship was noted between the number of Amphipods and pond snails in each unit. Amphipods at 10 hours after the recovery to the ground frequently exhibited a movement of dropping straight-downward to the bottom of the units. Several Amphipods had their legs bent abnormally, which probably resulted from some physiological alterations during their embryonic development under microgravity. From the analysis of the video tape recorded in space, for Ostracods and Daphnia, a half of their population were looping under microgravity. Such looping animals could be observed still at the end of the 4 month stay in space. No looping behavior was noted for Amphipods and pond snails.

Animals↗
PubMed1998

[A case of polyangiitis overlap syndrome].

A 47 year old man was admitted to a local hospital because of fever and severe epigastric pain. Laboratory examination showed eosinophilia (9,812/microliter) and an elevated serum IgE level (934 IU/ml). Multiple hemorrhagic gastric ulcers and a left adrenal tumor was also found. The gastric ulcers were resistant to conservative therapy. On the eighth hospital day, total gastrectomy and left adrenalectomy were performed. Surgical specimens from the stomach and adrenal gland showed necrotizing angiitis with infiltration of eosinophils, and thrombus formation. Eosinophilia was persistant to the treatment by corticosteroid and immunosuppressant. Thereafter polymononeuropathy in lower limbs and necrotizing lesions in toes developed and were resistant to medication and gangrionic block. According to the clinical and pathological findings, we made diagnosis of this case as polyangiitis overlap syndrome with some features of Allergic granulomatous angiitis and Polyarteritis nodosa.

Churg-Strauss Syndrome↗
PubMed1997

Atrial conduction abnormalities in patients with systemic progressive sclerosis.

BACKGROUND: Atrial abnormalities in patients with progressive systemic sclerosis have not been evaluated in terms of intra-atrial conduction. We hypothesized that a delay in atrial conduction in these patients might produce diastolic abnormalities as well as atrial arrhythmias. OBJECTIVE: To evaluate the atrial function of patients with progressive systemic sclerosis by using echocardiography to measure the intra-atrial electromechanical activation coupling interval. METHODS: Twenty patients with progressive systemic sclerosis were assessed by Doppler echocardiography. Twenty age-matched healthy controls were also evaluated. Two-dimensional guided M-modes of ventricular long axes were recorded using simultaneous phono- and electrocardiograms of the apical four chamber view at the right lateral, septal and left lateral sites of the atrioventricular rings. Transmitral and tricuspid pulsed Doppler flow velocities were also recorded. Filtered P wave duration was measured on the signal averaged ECG to determine the duration of atrial electrical activation. RESULTS: There was a delay in P on the electrocardiogram (P) at the onset of atrial contraction on long axis M-modes at all three atrioventricular ring sites in patients with progressive systemic sclerosis as compared with controls (P-right; 56 +/- 13 vs 47 +/- 10 ms, P-septal; 74 +/- 14 vs 55 +/- 10 ms, and P-lateral; 93 +/- 16 vs 72 +/- 11 ms, P < 0.01). Inter-atrial conduction time [(P-lateral)-(P-right)] was delayed in patients with progressive systemic sclerosis, compared with healthy controls (37 +/- 15 vs 25 +/- 6 ms, P < 0.01). Mitral A waves acceleration and deceleration times were also decreased in the patients. The interval was prolonged between P to the onset and the peak of the A wave in transmitral flow. Duration of the filtered P wave was significantly prolonged in progressive systemic sclerosis as compared with controls (124 +/- 12 ms vs 106 +/- 8 ms, P < 0.01). PQ intervals, E waves and acceleration and deceleration times did not differ significantly in progressive systemic sclerosis vs, controls. The A wave acceleration rate on transmitral flow (peak A wave velocity/acceleration time) showed a significant correlation with inter-atrial conduction delay (r = 0.55, P < 0.01). CONCLUSIONS: Intra-atrial electromechanical coupling intervals were delayed in patients with progressive systemic sclerosis. Thus, the mechanical late diastolic filling time due to atrial contraction in the total diastolic phase was severely limited, and this resulted in a restricted mitral A wave. We should therefore evaluate patients with progressive systemic sclerosis for significant atrial abnormalities.

Atrial Function↗
PubMed1997

Myogenic responses of isolated lymphatics: modulation by endothelium.

OBJECTIVE: To characterize the effect of increases of intraluminal pressure on the spontaneous diameter oscillations of isolated lymphatics and on the maximum and minimum diameter, in the presence and absence of endothelium. METHODS: Afferent lymphatics were isolated from rat iliac lymph nodes. After cannulation of both ends, lymphatics were equilibrated for 60 minutes at a pressure of 6 cm H2O, and then changes in diameter oscillations to increases in perfusion pressure (from 2-10 cm H2O, were measured. The endothelium was removed by intraluminal infusion of air. Changes in diameter were expressed as a percentage of the corresponding passive diameter obtained in Ca(2+)-free solution. RESULTS: Isolated lymphatics showed phasic spontaneous constriction and dilation (approximately 50 to approximately 150 microns). Removal of extracellular Ca2+ abolished spontaneous diameter oscillations, and the passive diameter increased from 183.0 +/- 5.3 to 205.1 +/- 8.8 microns as pressure increased from 2 to 10 cm H2O. In response to increases in pressure, the normalized minimum diameter (Dmin) increased (from 30.1% +/- 1.1% to 54.8% +/- 1.9% while the normalized maximum diameter (Dmax) of lymphatics did not change. With increasing pressure the amplitude of vasomotion (Dmax-Dmin) decreased, whereas the oscillation frequency increased. Removal of endothelium significantly reduced Dmax; hence, the oscillation amplitude decreased while the frequency increased. Also, endothelium removal elicited a significant change in the slope of the pressure-Dmax curve (from 0.01 +/- 0.4 to -1.43 +/- 0.34). CONCLUSIONS: Increases in intraluminal pressure greatly affect the spontaneous vasomotion of lymphatics and activate the myogenic mechanism intrinsic to the smooth muscle. In addition, endothelial factors are important to maintain adequate lymphatic vasomotion. These findings suggest that intraluminal pressure and endothelial factors can be important contributors to the tone and pumping activity of lymphatics in vivo.

Animals↗
PubMed1997

[A test of a hypothesis of automatic phonological processing of Kanji words].

This paper aims to examine a hypothesis that phonological processing should occur in Japanese Kanji words as well as in Kana words, but automatic in Kanji words. In Experiment 1, subjects performed concurrent articulation or finger tapping during a semantic processing task of Kana words with 2 to 4 phonemes, for which phonological processing should be indispensable. Concurrent articulation was found to eliminate the phoneme number effect found in the control condition, but finger tapping was not. This result indicates the effectiveness of concurrent articulation in articulatory suppression. In Experiment 2, the materials were changed to Kanji words, for which phonological processing had been supposed to be dispensable, and subjects performed the same task. The results showed no phoneme number effect even in the control condition, and the reaction time in the concurrent articulation condition was delayed significantly. These results suggest the existence of automatic phonological processing of Kanji words. Finally, the pertinence of this hypothesis was confirmed by applying it to the explanations of 3 kinds of Japanese dyslexia.

Adult↗
PubMed1997

Macrophage-induced nitric oxide and prostanoid dependent relaxation of arterial smooth muscles.

We have studied mechanisms of vasodilation induced by supernatant fluid of rat macrophages (Mø), using an arterial bioassay preparation. The cells emigrated by an intraperitoneal injection of thioglycollate were isolated and cultured for 12 h in RPMI 1640 medium with and without 2.0 mM L-arginine. More than 98% of the isolated cells clearly demonstrated Wright's esterase staining and phagocytosis of acetylated low-density lipoprotein. The bioassay preparation was made of dog isolated femoral arteries with and without the endothelium. The supernatant of macrophages cultured in the L-arginine-free RPMI 1640 caused a significant reduction of the precontraction in the bioassay rings, being approximately 51.6-66.7% of sodium nitroprusside (SNP) induced maximum vasodilation in each ring. The supernatant of macrophages cultured in the RPMI 1640 containing 2.0 mM L-arginine produced a significantly smaller relaxation (approximately 32.3-33.3%). The Mø-induced vasodilation was significantly inhibited by the coculture of the macrophages with 1 microM dexamethasone, 10 microM cycloheximide, 50 microM N omega-nitro-L-arginine methyl ester (L-NAME), 10 microM indomethacin, or 10 microM aspirin. The L-NAME-induced inhibition was significantly reversed by an additional treatment with 100 microM L-arginine. The coculture with both L-NAME and indomethacin caused a reduction of the Mø-induced vasodilation (approximately 12.5-13.4%) similar to reductions produced by dexamethasone (approximately 10.8-12.1%) and cycloheximide (approximately 11.4-12.4%). Coculture with 10 micrograms/mL bacterial lipopolysaccharide caused a slight facilitation of the Mø-induced vasodilation (approximately 78.2-79.6%). These findings suggest that supernatant fluid of rat exuded macrophages cultured with low concentrations of L-arginine causes an endogenous nitric oxide (NO) and vasodilative prostaglandin dependent relaxation of arterial smooth muscles.

Animals↗
PubMed1996

Granulocyte-colony stimulating factor produced by pancreatic carcinoma.

CONCLUSION: A rare case of granulocyte-colony stimulating factor (G-CSF) produced by carcinoma of the pancreas has been reported. BACKGROUND: This is the first case showing high G-CSF concentration in the aspirated tumor fluid (mucin) at its early stage without leukocytosis. METHODS: The tumor, detected incidentally in a 64-yr-old male, was removed by a distal pancreatectomy. The mass was 7.0 x 6.5 x 4.5 cm, and was histologically diagnosed as cystadenocarcinoma with prominent sarcomatous transformation. It was classified as anaplastic carcinoma. RESULTS: After 4 wk of resection, progressive leukocytosis was observed. Seven weeks after the operations, the peripheral leukocyte count increased to 126,000/mL. After 8 wk of resection, the patient died of recurrence. The serum G-CSF concentration was elevated after recurrence. The preserved mucin contained in the cystic components of the resected specimen had a G-CSF concentration higher than 2400 pg/mL. G-CSF is a known cytokine and an etiologic agent in paraneoplastic syndromes. An early diagnosis can, therefore, be made prior to the manifestation of clinical symptoms by the evaluation of the aspirated tumor fluid. This can lead to the prevention of the paraneoplastic syndrome with inhibitory cytokines in future.

Cystadenocarcinoma↗
PubMed1996

[Clinical study on bacteremia in patients with liver cirrhosis].

Infections and fever are frequent in patients with liver cirrhosis. Study on bacteremia in cirrhotic patients has not been reported in Japan. In a 16 year period from 1979 to 1994, we collected 39 cases with 40 episodes and 44 microorganisms of bacteremia for this study. The incidence of bacteremia in cirrhotic hospital admissions was 4.8% (39/808). Gram negative bacteria were the predominant microorganisms of bacteremia (66%, 29/44). Among them, Escherichia coli, Klebsiella pneumoniae, Vibrio sp. were the three most commonly detected microorganisms. Pseudomonas aeruginosa bacteremia has not been detected. Laboratory data of cirrhotic patients showed that positive blood culture patients had significantly lower serum albumin, prothrombin time and hepaplastin test than negative patients. Focal infection could be diagnosed in only 45% (20/44). The mortality rate was 28% (11/39), but the bacteremia related death (by septic shock) were only 2 cases. The other causes of death were hepatic failure in 9 cases. In conclusion, bacteremia is a important complication of liver cirrhosis. Blood culture is necessary in cirrhotic patients with fever.

Adult↗
PubMed1996

[The influence of long-term memory on visuo-spatial sketchpad: a test of a new factor causing recency effects].

Three immediate serial recall experiments, using articulatory suppression examined the influence of visual long-term memory on visuo-spatial sketchpad. In Experiments 1 and 2, serial recall rates of unfamiliar figures, familiar figures, and numbers were investigated. The results showed that the more visual long-term memory the stimuli evoked, the more salient recency effects and primacy effects occurred. Based on these results, the following process is hypothesized to be one of the factors causing recency effects. If the visual information of items inputted into visuo-spatial sketchpad is already in long-term memory, only their retrieval cues are formed and retained. Thus, other information is erased from visuo-spatial sketchpad, which makes more room, so that subsequent items are inputted into visuo-spatial sketchpad. In Experiment 3, reaction times of a visual secondary task during presentation were measured. The results indicated that there was more room in visuo-spatial sketchpad when primacy and recency effects occurred, which supported the hypothesis. Finally, the interaction of working memory and long-term memory is discussed.

Adult↗
PubMed1996

Primordial germ cells in the embryos of Medaka fish.

In the second International Microgravity Laboratory (IML-2) mission in 1994, four small Japanese killifish (Medaka, Oryzias latipes) made a space travel of 15 days aboard a space shuttle. These four adult Medaka fish successfully mated in space for the first time among vertebrate animals. Moreover, the eggs they laid developed normally, at least in their external appearance, hatching as fry (baby fish) in space. Fish mated and laid eggs every day during the first week. Near the end of the mission most of the eggs had a well-developed body with two pigmented eyes. In total, 43 eggs were laid (detected), out of which 8 fry hatched in space, as truly 'space-originated' babies. A further 30 fry hatched within 3 days after landing. This is the normal hatching rate, compared with the ground-based data. Among the 8 space-originated fry, four were killed for histological sections, and germ cells at the gonadal region were counted for each fry. Their numbers were in the range of the germ cells of the normal control fry (ground-kept samples). Thus, as embryos developed normally in their external appearance, inside the embryos the formation of primordial germ cells took place normally in space, and their migration to the genital ridges was not hindered by microgravity. The two of the remaining space-originated fry have grown up and been creating their offspring in the laboratory. This proved that the primordial germ cells formed in space were also normal from a functional point of view. The four space-travelled adult fish re-started mating and laying eggs on the 7th day after landing and continued to do so every day afterward. Fertilization rate and hatchability of these eggs were as high as the eggs laid by the laboratory-kept fish. This fact implies that in gametogenesis of adult fish, there are no specific stages of germ cells extremely susceptible to microgravity.

Animals↗
PubMed1995

Laparoscopic splenectomy in children. Preliminary results and comparison with the open technique.

To determine the safety and efficacy of laparoscopic splenectomy (LS) in children, a retrospective review of our preliminary experience using LS was compared to results in patients who previously underwent open splenectomy (OS). From July 1993 to January 1995, we performed eight LS procedures in six children with hereditary spherocytosis (HS) and two with immune thrombocytopenic purpura (ITP). Laparoscopic cholecystectomy was simultaneously done in one case with HS. There were 4 males and 4 females who ranged in age from 5 to 15 years--an average age of 8.8 years. Two cases in the early series required a counterincision because of bleeding. Eleven patients who previously underwent OS in our department were used to compare demographics, operative courses, and surgical outcomes. The ages, genders, diseases, body weights, and spleen weights were comparable between LS group and OS groups. The operative time for the LS group was statistically longer than for the OS group (226 +/- 24 min vs 101 +/- 8 min, P < 0.001). The estimated blood loss in the LS group was similar to that of the OS group (100 +/- 39 ml vs 73 +/- 11 ml. P = 0.97). There were no peri- or postoperative complications in two groups. The postoperative hospital stay of LS group was statistically shorter than that of the OS (6.8 +/- 0.6 days vs 10.4 +/- .05 days, P < 0.0001). LS provided better cosmesis and minimized trauma in children over OS. LS appears to be a safe and effective procedure in children, and is useful in the management of pediatric patients with HS or ITP.

Adolescent↗
PubMed1995

5-Hydroxytryptamine-induced NO-dependent relaxation in isolated strips of monkey popliteal lymph nodes.

5-Hydroxytryptamine (5-HT, 0.01-100 microM) and 5-carboxamidotryptamine (5-CT, 0.001-10 microM) produced dose-related relaxations in strips cut from monkey popliteal lymph nodes precontracted with a perfusion of Krebs bicarbonate solution containing 80 mM KCl. These 5-HT agonists caused no significant effect on the basal tone of the lymph node strips. The 5-HT-induced relaxation is competitively antagonized by pretreatment with a selective 5-HT1-like receptor antagonist, methiothepin (0.01-0.1 microM). Schild plot analysis showed that the pA2 value and slope of methiothepin against 5-HT were 8.80 +/- 0.11 and 0.99 +/- 0.07 (n = 6), respectively. Pretreatment with methysergide (0.01-0.1 microM) significantly attenuated the 5-HT-induced relaxation of the strips. On the other hand, treatment with ketanserin (0.01-0.1 microM) and ICS-205-930 (0.01-0.1 microM) caused no significant effect on the 5-HT-or the 5-CT-induced relaxation. The 5-HT-induced relaxation was significantly reduced by 10 microM NG-monomethyl-L-arginine, which was reversed by 1 mM L-arginine. The relaxation in the lymph node strips was also significantly reduced by treatment with 10 microM methylene blue but not with 30 microM aspirin. These results suggest that 5-HT1-like receptors exist in the monkey popliteal lymph nodes. Stimulation of these receptors produces an endogenous nitric oxide (NO)-dependent relaxation in lymph node smooth muscle through an activation of cytosolic guanylate cyclase in the cells.

Animals↗
PubMed1994

Cloning and expression of myelin-associated oligodendrocytic basic protein. A novel basic protein constituting the central nervous system myelin.

We have screened genes predominantly expressed in the rat spinal cord, and we report here cloning of the most abundant unknown gene. It is a novel member of the central nervous system (CNS) myelin-constituting proteins, myelin-associated oligodendrocytic basic protein (MOBP). MOBP is abundantly expressed specifically in oligodendrocytes at the mRNA level only next to myelin basic protein (MBP) and proteolipid protein. Two isoforms have been confirmed. One of them has proline-rich tandem repeats and has 84% homology with human counterpart in terms of predicted amino acid sequences. The cDNA-derived primary structure predicts a small, soluble, basic protein. The immunoelectron microscopy has shown that MOBP is expressed throughout compact myelin. All these characteristics are similar to MBP. One definite difference between MBP and MOBP is that MOBP is expressed exclusively in the CNS myelin. These findings suggest that MOBP shares some important functions with MBP in the CNS myelin such as myelin compaction.

Amino Acid Sequence↗
PubMed1994

Isolation of a cDNA clone encoding a novel membrane protein expressed in lymphocytes.

By subtractive hybridization using single-stranded phagemids with directional inserts, we isolated a mouse cDNA clone, LSM-1, from temperature-sensitive Abelson virus-transformed immature B cells whose differentiation was being induced after the shift from the permissive (35 degrees C) to the non-permissive temperature (39 degrees C). LSM-1, which encodes an as yet unknown peptide of 197 amino acids, has a putative signal sequence and a trans-membrane region, and is expressed in B- and T-cell lines, in spleen, thymus, and bone marrow of adult mice, and in embryos.

Amino Acid Sequence↗
PubMed1993

Molecular cloning of a novel putative G protein-coupled receptor (GPCR21) which is expressed predominantly in mouse central nervous system.

A novel cDNA clone encoding a putative G protein-coupled receptor (named GPCR21) was isolated from a mouse brain cDNA library along with its homologue, GPCR01 (the mouse counterpart of previously reported rat receptor R334 [(1991) FEBS Lett. 292, 243-248]) by the polymerase chain reaction using degenerate oligonucleotide primers. Northern blotting and reverse transcription-polymerase chain reaction analyses showed predominant expression of these two receptors in the central nervous system. In situ hybridization analysis revealed their prominent expression in the limbic system and further demonstrated the differential distribution of their mRNAs in mouse brain. Although the ligands for these receptors are yet to be identified, the significant sequence homology between these receptors suggests that they constitute a new receptor subfamily and they possibly represent different receptor subtypes for an unknown neurotransmitter.

Amino Acid Sequence↗