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Biomedical subjects

M Nakazawa

Publications and source records attributed to M Nakazawa.

At least 307 records · Page 17Linked to original sources
PubMed1992

[Transient patterns of serotonergic innervation in the rat visual cortex--normal development and effects of enucleation].

Serotonergic innervation formed transient dense aggregation in all rat primary sensory areas during early postnatal development. In the normal rat visual cortex, there were three stages in the transient aggregation of serotonin immunoreactive fibers from postnatal day (PND) 2 to 15. Primary aggregates appeared in the subplate prior to the differentiation of layer IV, and moved upward to the lower layer of cortical plate to form secondary aggregates. Secondary aggregation gave rise to ascending fibers on the cortical surface which were roughly grouped in columns (tertiary aggregation). The serotonin fibers of the tertiary aggregates were arranged in a lattice-like pattern in layer I, and were significantly altered either in size of distribution area or column number after monocular or binocular enucleation. These data indicate that the lattice-like pattern of serotonin innervation in neonatal rats may be an evolutionary precursor of the "blobs" seen in the higher primates.

Animals↗
PubMed1992

Low-level infection with the nematode Nippostrongylus brasiliensis induces significant and sustained specific and non-specific IgE antibody responses in rats.

Specific and non-specific IgE antibody responses were studied in SD rats infected with between 5 and 2500 Nippostrongylus brasiliensis (NB) larvae. In rats with 2500 NB larvae, specific IgE antibody, measured by enzyme-linked immunosorbent assay (ELISA) using NB excretory/secretory substance as antigen, reached a peak at 4 weeks of infection and gradually declined. On the other hand, in rats infected with 10 or 100 NB larvae, specific IgE was induced at 4 weeks of infection and the level continued to rise until at least 8 weeks after infection. The level at 8 weeks was significantly higher in rats infected with 10 or 100 larvae than in rats infected with 2500 larvae. The results indicate that the low-level infection induced a much more sustained specific IgE response than that induced after heavy infection. However, the level of specific IgG was correlated with the dose of infection, and reached a plateau 6 weeks after infection. Total serum IgE increased significantly even in rats infected with five larvae, a dose which did not induce detectable specific IgE. The kinetics of the production of total IgE was different in rats with light and heavy infections. In rats infected with five or 10 larvae, total IgE increased slowly and reached a plateau 4 weeks after infection. On the other hand, rats infected with more than 500 larvae showed a remarkable rise in total IgE at 2 weeks of infection; this rise gradually declined thereafter. Six weeks after infection, total IgE levels were almost the same (2-3 micrograms/ml) in rats infected with 10-2500 NB larvae. These results show that low-level NB infection induces a significant and sustained specific and non-specific IgE response in rats.

Animals↗
PubMed1992

[Radiotherapy in the conservative management of breast cancer].

Breast conserving therapy is now considered standard treatment in patients with early breast cancer, and it yields equal local control and survival equal to those of radical mastectomy, in Europe and the United States. After many reports from western countries, Japanese surgeons started conservative treatment for early breast cancer. The aim of radiotherapy is to eradicate residual tumor after quadrantectomy or lumpectomy. Indication for this management by Fujio Kasumi at the Cancer Institute Hospital is T1, N0, M0. We reported here the method of radiotherapy, that is energy of photon, treatment field and total dose, which are discussed by the study group of the Japanese Society for Therapeutic Radiology and Oncology.

Breast Neoplasms↗
PubMed1991

Detection of Streptococcus suis type 2 in tonsils of slaughtered pigs using improved selective and differential media.

New selective and differential media were devised for the isolation and identification of Streptococcus suis type 2. The selective medium (NNCC) agar) was Todd-Hewitt broth containing 1.5% Bactoagar and 5% defibrinated sheep blood with addition of sodium azide (50 micrograms/ml), nalidixic acid (25 micrograms/ml), colistin (12.5 micrograms/ml) and crystal violet (2 micrograms/ml). The differential medium consisted of heart infusion agar and antiserum specific only for S. suis type 2. In a total of 291 pigs tested by a combination of these media, S. suis type 2 was isolated and confirmed from 40 of them (13.7%).

Agar↗
PubMed1991

Partial agonist activity of celiprolol, a cardioselective beta-antagonist.

The beta-antagonistic effects of celiprolol were assessed in isolated guinea-pig preparations. The pA2 values obtained were 7.84 +/- 0.07, 7.79 +/- 0.06 and 6.45 +/- 0.11 against the positive chronotropic and inotropic effects in the atria and relaxant effects in the trachea induced by isoproterenol, respectively, indicating that celiprolol is a cardioselective beta-antagonist. Celiprolol produced slight positive chronotropic and inotropic effects in atrial preparations and a uniquely strong relaxant effect in tracheal preparations. All these effects were attenuated by pretreatment with 10(-6) M atenolol or 10(-6) M propranolol. In pithed rats, celiprolol produced pressor responses at doses lower than 0.03 mg/kg and hypotensive responses at doses higher than 0.3 mg/kg. It produced sustained increases in heart rate in all doses applied. These effects were attenuated by pretreatment with 1 mg/kg of propranolol. The pressor response might be taken to be a reflection of an increase in cardiac function mediated by cardiac beta 1-receptor stimulation, while the hypotension may be ascribed mainly to stimulation of beta 2-adrenoceptors in the vascular system. It is concluded that celiprolol exerts a uniquely strong partial agonist activity at beta 2-adrenoceptors.

Adrenergic beta-Agonists↗
PubMed1991

Na+/H+ exchange is not operative under low-flow ischemic conditions.

Using 31P-NMR the existence of Na+/H+ exchange system and its contribution to intracellular pH (pHi) regulation were examined in the isolated isovolumic rat heart under physiological and pathophysiological conditions. Ethylisopropylamiloride (EIPA) was used as a tool to search into the role of Na+/H+ exchange system. In the normal well-oxygenated heart dose-dependent negative chronotropic effects were observed with 10(-6) to 10(-5) M EIPA. After 10(-4) M the heart ceased to beat and a progressive fall of high energy phosphates compounds occurred. However, contrary to expectation pHi did not fall but rose after EIPA. In NH4Cl-loaded hearts removal of NH4Cl resulted in a fall of the pHi followed by a rapid recovery to the normal pHi. After 10(-5) M EIPA the fall of pHi became greater and there was no recovery within 35 min of observation period. This dose of EIPA, however, did not affect the time course of changes in the pHi during 60 min of low-flow ischemia (0.2 ml/min). It is concluded that pHi regulation following an acute acid loading is dependent on amiloride-sensitive Na+/H+ exchange. However, Na+/H+ exchange system does not play an important role in maintenance of the pHi under normoxic or ischemic condition. In the normoxic heart EIPA produced a decrease in heart rate without producing any change either in myocardial energy metabolism or in pHi. Thus, the compound could be categorized as a bradycardic agent.

Amiloride↗
PubMed1991

Investigations of origins of serotonergic projection to developing rat visual cortex: a combined retrograde tracing and immunohistochemical study.

The present study investigated whether the raphe neurons which give rise to the transient serotonergic fibers in the visual cortex of neonatal rats persist or disappear as the rats mature. Three experiments were performed employing the WGA-apoHRP-Au retrograde transport technique in conjunction with 5-HT or WGA-HRP immunohistochemical staining. WGA-apoHRP-Au was injected into the primary visual cortex of all rats 9 days postnatally. In the first experiment, the animals were examined after 2 days; retrogradely labeled cells were observed in the dorsal raphe nucleus (DR), the median raphe nucleus (MR), and in the B9 and B6 cell groups; the majority (82.5%) of the cells was serotonergic. In the second experiment, the examinations took place following a survival time of 8 weeks: virtually all of the original raphe-visual cortical serotonergic neurons were found to the present. In the third experiment, also performed after 8 weeks relabeling the raphe-visual cortical neurons by WGA-HRP, it was found that 37.2% of the raphe neurons which had projected to the neonatal visual cortex no longer possessed such projections.

Aging↗
PubMed1991

Isolation of wound-specific cDNA clones from a cDNA library prepared with mRNAs of alkali-burned rabbit corneas.

Alkali burn is one of the most severe corneal injuries. In order to gain a better understanding of the healing of alkali-burned corneas, it is necessary to identify and characterize proteins that are specifically synthesized by the injured corneal tissues. In this study, we developed a useful procedure to identify and isolate cDNA clones that encode messenger ribonucleic acids (mRNAs) that are specific and/or abundant in alkali-burned rabbit corneas (ARCs), but absent in normal rabbit corneas (NRCs). At first, a cDNA library was prepared by cloning cDNA of mRNA isolated from ARCs into the lambda ORF-8 vector. A differential plaque hybridization was used to screen 2.5 x 10(4) plaque-forming units (pfu) from an ARC cDNA library using 32P-labeled cDNAs prepared from mRNA of ARCs and NRCs. Thirty-seven cDNA clones of mRNAs specific for ARCs were identified and isolated in their pureform. The cDNA inserts of these lambda ORF-8 phages were subcloned into the pSM216 vector by in vivo recombination. The cDNA inserts then were characterized by restriction enzyme digestion, i.e., BamHI, HindIII, and EcoRI. The size of the cDNA inserts ranged from 210 to 5,000 base pairs. Using Northern blot hybridization of total RNA prepared from polymorphonuclear neutrophils, mononuclear leukocytes, alkali-burned corneas, and normal corneas, the cDNA clones were divided into three groups. Five cDNA clones encoded mRNA of corneal cells in ARCs. Twenty-four cDNA clones derived from mRNA of inflammatory cells were present in alkali-burned corneas, but Northern blot hybridization failed to identify mRNA of discrete sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalies↗
PubMed1991

Typing of Rhodococcus equi isolated from submaxillary lymph nodes of pigs in Japan.

Isolation of Rhodococcus equi from the submaxillary lymph nodes of pigs, with or without caseous lymphadenitis, and typing of the isolates by two serological methods were carried out. The rate of isolation of the organisms from the lymph nodes of pigs was 5 times higher in the lymph nodes with caseous lymphadenitis than in those without the lesion. Of 219 isolates, 146 (66.7%) were typable by the method of Prescott, while all the 219 isolates (100%) were typable by the method of Nakazawa et al. The most frequently isolated were serotype 2 of Prescott (identical to serogroup 16 of Nakazawa et al.), and serogroup 3 of Nakazawa et al., which did not correspond with any serotypes of Prescott. Serotypes/serogroups of R. equi from pigs were thus first clarified in Japan.

Actinomycetales Infections↗
PubMed1991

A quantitative analysis of hemodynamic effects of the right ventricle included in the circulation of the Fontan procedure.

BACKGROUND: Right heart hemodynamics were analyzed with a catheter-mounted velocity meter in seven patients after direct atrioventricular anastomosis for Fontan procedure (RV group) and were compared with those obtained in eight patients after direct atriopulmonary anastomosis (RA group). METHODS AND RESULTS: In the RV group, cardiac output was 2.7 +/- 0.6 l/min/m2; mean right atrial and pulmonary artery pressures were both 13 +/- 3 mm Hg; mean pulmonary artery wedge pressure was 7 +/- 5 mm Hg; left ventricular end-diastolic volume, determined angiographically, was 129 +/- 40% of normal; and its ejection fraction was 0.50 +/- 0.09. In the RA group, data were similar to those of the RV group except that right heart pressure were lower in the RV group, which was related to the preoperative condition of the pulmonary circulation. In the RV group, the fraction of ventricular forward flow of the total forward flow in the main pulmonary artery ranged from 0.21 to 0.46 and was not correlated with cardiac output or with any other parameter. The backward flow into the inferior vena cava at ventricular systole was greater than the atrial flow in two patients in whom cardiac output was less than 2.2 l/min/m2, whereas caval backward flow at atrial contraction was greater than ventricular flow in the other five patients, of whom four had a cardiac output greater than 3.1 l/min/m2. CONCLUSIONS: We conclude that the inclusion of right ventricle in the circulation of the Fontan procedure does not necessarily improve overall hemodynamics in most patients.

Adult↗
PubMed1991

Effects of environmental hyperthermia on cardiovascular function in the rat embryo.

Effects of hyperthermia on the cardiovascular function of the mammalian embryo have not been well defined. The effect of hyperthermia on the blood flow and umbilical artery blood pressure was studied in rat embryos at gestational d 12 by using a method developed in our laboratory. When the temperature was changed from 37 to 42 degrees C, the heart rate increased by 15% (n = 33). Mean umbilical artery blood pressure, measured by a servo-null micropressure system, decreased from 0.64 +/- 0.05 to 0.53 +/- 0.04 mm Hg (n = 11), whereas blood flow velocity at the conotruncus, a measure of cardiac output, obtained by a 20-MHz pulsed Doppler ultrasound flowmeter, increased by 36 +/- 11% (n = 11). Mean umbilical artery blood flow increased by 66 +/- 13% (n = 11) and its vascular resistance, calculated by ratio analysis, decreased from 3.7 (median) to 1.8 units. These changes returned to baseline values when the temperature was returned to 37 degrees C. The change in blood pressure was different from that seen in the chick embryo, indicating that there is species difference in the hemodynamic effect.

Animals↗
PubMed1991

[Pharmacological effects and metabolism of extracellular ATP].

Cells are equipped with complex mechanisms for synthesis of ATP and try to keep the intracellular level of this compound, which is indispensable for maintenance of normal function and integrity, as constant as possible. Thus, it is generally believed that ATP rarely cross the plasma membrane of viable cells. However, since the first report of Holton in 1959, the release of nucleotides from cells has become an established fact, and the physiological role and metabolism of the released ATP has become an important topic; potent actions of extracellular purine nucleotides and nucleosides have been recognized for many years. In 1972, Burnstock demonstrated that ATP has a transmitter role in certain types of nerves and proposed a concept of purinergic nerve. The receptor for purine nucleotides, designated as P2, as opposed to P1, by Burnstock in 1978 was further subclassified in 1985 into P2X and P2Y by himself, and we now have a train of P2 receptors, such as P2S, P2T, P2Z and so forth. In this review, I summarized the characteristics of these purinoceptors. Pharmacological effects and metabolism of extracellular nucleotides were discussed and a brief mention was made of ecto-nucleotidases.

Adenosine Triphosphate↗
PubMed1991

Effect of carvedilol on venous return: a mechanism of reduction in blood pressure.

We studied the effect of carvedilol, a beta-blocker with a potent alpha-blocking activity, on venous return in anesthetized dogs. Though 3 micrograms/kg of carvedilol caused a slight increase in blood pressure and total peripheral resistance, these changes disappeared by further doses of the agent. On the other hand, each dose of carvedilol (3-100 micrograms/kg) decreased venous return significantly and dose-dependently. These results indicate that the hypotensive effect of carvedilol mainly depends on the decrease in venous return rather than arterial vasodilation.

Adrenergic beta-Antagonists↗
PubMed1991

Hemodynamic effects of benazeprilat in the anesthetized dog with acute left ventricular failure.

To examine the hemodynamic effects of benazepril, an angiotensin converting enzyme inhibitor, in left ventricular failure, its active metabolite benazeprilat was administered during acute ischemic left ventricular failure in anesthetized open chest dog induced by repeated injections of plastic microspheres into the left coronary artery. The coronary embolization with microspheres resulted in a moderate and stable left ventricular pump failure characterized by increased left ventricular end-diastolic pressure (LVEDP) and decreased cardiac output (CO). Benazeprilat (30 micrograms/kg) administered intravenously after a stabilization period lowered LVEDP and maintained CO. The total peripheral resistance was reduced with benazeprilat. The oxygen consumption and the coronary blood flow were reduced with benazeprilat because of a decrease in wall tension and afterload. These results suggest that benazeprilat (benazepril) has beneficial effects for the treatment of acute left ventricular failure.

Acute Disease↗
PubMed1991

A case of multiloculated, intracranial epidermoid cyst in a beagle dog.

An intracranial epidermoid cyst was identified within the fourth ventricle of a male 10-month-old beagle dog. The cyst, which exhibited a multilocular structure, was lined by a stratified squamous epithelium and filled with desquamated keratin. In the region of the roof of the fourth ventricle, choroid plexus adherent to the cyst wall and secondary compression of the cerebellum were also seen.

Animals↗