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Biomedical subjects

M Nakazawa

Publications and source records attributed to M Nakazawa.

At least 325 records · Page 18Linked to original sources
PubMed1991

Experimental infections of mice and pigs with Streptococcus suis type 2.

Five inbred strains of mice were tested for their susceptibility to Streptococcus suis type 2 including the type strain, two isolates from meningitis in pigs and two isolates from tonsils of clinically healthy pigs. C57BL/6, ICR and ddY strain mice showed lower susceptibility to all strains of S. suis type 2 than BALB/c and SS strain mice. The type strain and the isolates from diseased pigs produced septicaemia and meningitis in BALB/c and SS mice inoculated with 10(8) colony forming unit of the bacteria and 60 to 100% of these infected mice died. On the other hand, mice inoculated with the isolates from healthy pigs showed mild clinical signs but none of them died. In BALB/c mice which died or developed nervous signs, the purulent meningo-encephalitis, myocarditis, ophthalmitis, labyrinthitis and otitis media were observed. S. suis type 2 antigen was demonstrated in these lesions by immunoperoxidase staining using rabbit S. suis type 2 antiserum. These results were similar to those in the experimentally infected pigs with these virulent and avirulent strains against mice. These results indicate that BALB/c and SS strains of mice are useful as an experimental model of S. suis type 2 infections in pigs, and that there are virulent and avirulent strains against mice and pigs among the strains of S. suis type 2.

Animals↗
PubMed1991

Effects of lidocaine on ischemic myocardial metabolism assessed by 31P-NMR in the isolated perfused rat heart.

Using an isolated perfused rat heart preparation, the protective effects of lidocaine and diltiazem on ischemic derangements of myocardial energy metabolism were studied with 31P-nuclear magnetic resonance spectroscopy. The hearts were perfused with a solution containing lidocaine (4.27 x 10(-5), 12.80 x 10(-5) M) or diltiazem (2.22 x 10(-7), 2.22 x 10(-6) M) for 15 min prior to the induction of global ischemia. The decrease in myocardial oxygen consumption rate, assessed as the product of heart rate and left ventricular systolic pressure (HR x LVP), was greater in diltiazem-treated than in lidocaine-treated hearts. Diltiazem and lidocaine significantly retarded the fall in myocardial pH during ischemia and improved ATP recovery after reperfusion. There was a good correlation between suppression of HR x LVP observed before induction of ischemia and decreased drop in pH during the early phase of ischemia in the diltiazem-treated groups (r = -0.78, p less than 0.01), but not in the lidocaine-treated groups. These results indicate that the beneficial effects of diltiazem on the ischemic myocardium are due primarily to the cardio-depressant effects. The beneficial effects of lidocaine cannot, however, be explained solely on the basis of the depression of oxygen consumption.

Animals↗
PubMed1991

Analysis of rhodopsin gene in patients with retinitis pigmentosa using allele-specific polymerase chain reaction.

Point mutations within the rhodopsin gene have been found recently in some patients with autosomal dominant retinitis pigmentosa (ADRP). Currently, four types of point mutations at codons 23, 58 and 347 have been identified. The purposes of this study were to establish simple methods for screening patients with retinitis pigmentosa (RP) to detect these point mutations, and to apply these methods to determine if these mutations are found in Japanese patients with RP. Utilizing the polymerase chain reaction (PCR), a one-step method was developed to detect point mutations at codon 23. This method was then applied to screen genomic DNAs from 30 patients with various types of RP, including ADRP, autosomal recessive RP, simplex RP, Leber's congenital amaurosis or Usher's syndrome. Subsequently, point mutations at codons 58 and 347 were detected by restriction enzyme digestion (Dde I or Msp I) of exons 1 and 5 amplified by PCR. To date, no mutations have been found in codons 23 and 58 in Japanese patients. By using the allele-specific PCR, however, two patients from one pedigree of ADRP were confirmed to have a C-to-T transition at the second nucleotide of codon 347, which results in the substitution of leucine for proline. Our findings indicated the availability of this simple method for detecting these point mutations.

Alleles↗
PubMed1991

Significant non-serotonergic raphe projection to the visual cortex of the rat. An immunohistochemical study combined with retrograde tracing.

The present study investigated the distribution of serotonergic and non-serotonergic raphe neurons with direct projections to the visual cortex. The study employed the WGA-apoHRP-Au retrograde transport technique combined with 5-HT immunohistochemical staining. Retrogradely labeled cells were observed in the dorsal raphe nucleus, the median raphe nucleus, and in the B9 and B6 cell groups. One notable finding was the great number of retrogradely labeled, non-5-HT immunoreactive cells. The average percentages of such cells in the various raphe regions were as follows: DR: 52% (n = 401); MR: 35% (n = 311); B9: 24% (n = 129); B6: 95% (n = 200). The present study demonstrated the presence of a significant proportion of non-serotonergic raphe region neurons projecting to the primary visual cortex in the rat. It is suggested that these neurons may complement the aminergic neurons as part of the ascending system which controls the functions of the visual cortex.

Animals↗
PubMed1991

Lysosomal acid hydrolases in vitreous fluid of patients with proliferative diabetic retinopathy.

Using a new method to collect vitreous fluid safely during vitrectomy, vitreous specimens were obtained from 18 eyes of diabetic patients with proliferative diabetic retinopathy (PDR) and from 14 eyes of nondiabetic patients. The activities of four lysosomal acid hydrolases in these samples were measured and compared with those in serum. Of these enzymes, only N-acetyl-beta-glucosaminidase (NAG), a suspected retinal angiogenic factor, showed higher activity in the vitreous than in the serum in both diabetic (P less than 0.005) and nondiabetic eyes (P less than 0.05). However, no significant difference was found in any enzyme activity between diabetic and nondiabetic samples. These results suggested that this enzyme apparently does not have a significant effect, at least on the pathologic condition, during the late stage of PDR, and that NAG is usually present at higher activity in the vitreous than in the serum of diabetic as well as nondiabetic patients.

Acetylglucosaminidase↗
PubMed1991

Species-specific differences in heterogonic development of serially transferred free-living generations of Strongyloides planiceps and Strongyloides stercoralis.

The direction of free-living development (homogonic vs. heterogonic) in Strongyloides stercoralis and Strongyloides planiceps was examined by successive transplantation of the uterine eggs of free-living females into a test tube culture system containing fresh feces. The eggs from the first-generation free-living females of S. stercoralis did not develop into second-generation free-living adult worms, but all developed into filariform larvae. However, the majority of S. planiceps eggs from the first-generation free-living females developed into second-generation free-living adults. By successive transfer of uterine eggs of each generation, 9 generations developed, and in every cycle more adult worms developed than filariform larvae. However, the number of free-living generations was not infinite; in experiments repeated twice, the number of worms developing from the eggs of eighth or ninth generations was too small to continue further culture. These findings indicate that the pattern of free-living development is different between the 2 species.

Animals↗
PubMed1991

[A double-labeling study of serotonin neurons that project to the visual cortex of developing rat brain].

Immunohistochemical studies of developing rat brains revealed aggregation of serotonin terminal fibers in the visual cortex at from 7 to 14 postnatal days. This aggregation is transient, disappearing 2 weeks after birth. The cells of origin of these serotonin terminals were investigated using double-labeling with retrogradely transported WGA-apoHRP-Au and serotonin immunohistochemistry. WGA-apoHRP-Au was injected into the rat visual cortex on the 9th day after birth. The rats were allowed to survive for 2 days and sacrificed with perfusion. Cryostat sections of the brain were processed with silver-enhancement to develop the retrogradely transported WGA-apoHRP-Au, and then serotonin immunohistochemistry was performed. Double-labeled cells that were labeled with WGA-apoHRP-Au and serotonin-immunoreactive were found mostly in the raphe medianus and raphe dorsalis in rostral and caudal sections of the mesencephalon, respectively.

Animals↗
PubMed1991

[Conotruncal repair of tetralogy of Fallot under 2 years old].

From October 1985 to September 1990, a repair within the conotruncal portion of the right ventricle-Conotruncal repair-was used for the primary repair of consecutive 34 patients with tetralogy of Fallot under the age of 2 years. There were three summarized points of this maneuver: the first was non-use of the tricuspid septal leaflet for closure of the ventricular septal defect, the second was short patch infundibuloplasty with a large monocusp, and the last was total resection of the infundibular septum. Length of the patch infundibuloplasty was just 30% of the right ventricle length according to our formula: 30% of RV (cm) = 1.28 X BSA (m2) + 1.10. The VSD patch was placed between the pulmonary annulus and the ventricular septal crest, consisting of the membranous flap and the posterior extension of the trabecula septomarginalis. The right ventricular (RV) to systemic arterial pressure ratio was 0.49 +/- 0.15 (N = 33) and central venous pressure was 10.2 +/- 1.9 cmH2O (N = 33) six hours after ICU admission and 8.4 +/- 1.5 cmH2O (N = 7) 18 days after operation. RV end-diastolic volume showed no increase after operation: 105 +/- 31 before repair to 104 +/- 23% of Normal after repair in the same patients. Post-operative intubation period was 14 +/- 8 hours and hospital admission period was 17 +/- 6 days after operation. All patients were in sinus rhythm. The 28% of patients showed incomplete right bundle branch block (RBBB) and other 28% of patients showed complete RBBB.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Surgical Procedures↗
PubMed1991

[Reactivity of sevoflurane with carbon dioxide absorbents--comparison of soda lime and Baralyme].

The reactivity of sevoflurane with carbon dioxide absorbents, soda lime and Baralyme which are commercially available carbon dioxide absorbents, was studied. A closed circuit system which was made only for this investigation was set up without rubber. Sevoflurane 5% was circulated for 17 hours. The circulated gas was analyzed by gas chromatography (GC) and degradation products were identified by a gas chromatography-mass spectroscopy (GC-MS) as fluoromethyl 2-methoxy-2, 2-difluoro-1-(trifluoromethyl) ethyl ether, fluoromethyl 2-methoxy-2-fluoro-1-(trifluoromethyl) vinyl ether, and its isomer. These degradation products of sevoflurane from soda lime and Baralyme were the same substances. The rate of degradation by soda lime was 0.88% +/- 0.306, while that by Baralyme was 3.40% +/- 0.501. Baralyme decomposed sevoflurane about four times more than soda lime. There are two possible explanations for these results. One is the Baralyme contains more potassium hydroxide than soda lime. The other is that soda lime absorbs sevoflurane more because it contains more silica.

Absorption↗
PubMed1991

Developmental changes in human megakaryocyte ploidy.

Megakaryocytes (MK) obtained from the differentiation of MK colony-forming units (CFU-MK) were grown from fetal liver, cord blood, and adult marrow in liquid culture containing aplastic plasma. Ploidy distribution was studied by a double-staining technique and flow cytometry and MK maturation by ultrastructural techniques. Cultured MK from fetuses and neonates were small sized (about 10 microns) in comparison to adult MK. They were mature cells that contained large membrane complexes as previously found in vivo. Only 2N and 4N MK were usually present in 8- to 10-week-old fetus cultures; 8N MK were detected at 20 weeks of gestation and in neonates. Higher ploidy classes were present in culture from adults but with a much lower frequency than in marrow. Therefore, a progressive shift to higher ploidy and an increase in MK size were observed simultaneously during development. Interleukin 3 (IL-3) increased MK proliferation as in adults but abrogated MK ploidization of 20-week-old fetus culture. The present results suggest that the changes occurring during ontogenesis are related to intrinsic MK modifications because no inhibitor of MK ploidization could be detected in fetal cultures.

Aging↗
PubMed1991

IgE antibody production in rats against multiple components of excretory-secretory products of the nematode Nippostrongylus brasiliensis.

Infection with the nematode Nippostrongylus brasiliensis (NB) induces the intense production of specific and non-specific immunoglobulin E (IgE) in rats. In the present study, we analysed NB-derived allergenic substances and the variability of IgE antibody production in response to these allergens in outbred Sprague-Dawley rats. Two kinds of crude allergens were used: the excretory-secretory products (ES) of adult NB, and an extract of homogenized adult worms (AW). ELISA showed that IgE antibody titres to ES were more than five times higher than the titres to AW. In the homologous passive cutaneous anaphylaxis (PCA) reaction using serum from infected rats, as little as 50 micrograms of ES had a maximal PCA activity, while even 1 mg of AW still gave a slightly lower PCA titre. Thus, it appeared that ES contained more allergen than AW at the same amount of total proteins. By immunoblot analysis, at least six components were recognized by IgE antibodies from infected animals, and these components were exactly the same in both ES and AW. The results indicated that the allergenic components in ES and AW were the same molecules, and that only those molecules which could be excreted or secreted from living worms were allergenic. Among the array of allergens, 130,000 and 70,000 molecular weight (mw) molecules were commonly recognized by IgE from all serum samples examined, while other components of the allergens were recognized variably by IgE antibodies from individual animals. These findings suggested that individual animals varied considerably in their IgE antibody production to the different constituents of the nematode allergens.

Animals↗
PubMed1990

Lack of significantly positive correlations between elemental concentrations in hair and in organs.

Elemental concentrations (Ca, Cu, Fe, Mg, P, Se and Zn) in the hair of Japanese were examined in relation to those in internal organs (cerebrum, cerebellum, heart, spleen, liver, kidney and rib). No significantly positive correlation was found between elemental concentration in hair and that in internal organ. This result indicates the restricted use of hair as a medium for the estimation of nutritional status of the essential elements examined in the present study, at least on an individual basis. The correlations between the concentrations in organs are also presented.

Bone and Bones↗
PubMed1990

Expression of platelet glycoprotein Ib by cultured human megakaryocytes: ultrastructural localization and biosynthesis.

Glycoprotein Ib (GPIb), the receptor for von Willebrand factor, is a two-chain member constituent of the platelet/megakaryocytic lineage. Studies on its expression have been hampered by the difficulties in obtaining purified megakaryocytes in a sufficient number. We report a suspension liquid culture procedure that allowed isolation of more than 1 x 10(6) megakaryocytes with a purity ranging from 3% to 88% from the blood of patients with chronic myeloid leukemia, from fetal liver or from normal human bone marrow. GPIb was detected on the plasma membrane of all maturing megakaryocytes and also of promegakaryoblasts devoid of demarcation membranes. GPIb was detected on demarcation membranes of maturing megakaryocytes but was absent from all other organelles, including alpha granules. Biosynthesis of 35S-methionine labeled megakaryocytes showed that GPIb with similar electrophoretic mobility to the platelet molecule was synthesized and that it was also composed of two chains, since its molecular weight shifted in reducing conditions from 170 Kd to 145 Kd. The beta chain remained undetectable after methionine metabolic labeling, but it was immunoprecipitated after 3H-leucine metabolic labeling, confirming that this subunit is devoid of methionine. GPIb was associated with GPIX, as it is in platelets, since anti-GPIb antibodies coprecipitated a 17 Kd polypeptide.

Adult↗
PubMed1990

Interrelationship between the concentrations of some elements in the organs of Japanese with special reference to selenium-heavy metal relationships.

Multi-element analyses were conducted on internal organs (cerebrum, cerebellum, heart, spleen, liver and kidney) of Japanese obtained from 45 forensic medical autopsy cadavers. Elements analyzed and analytical methods were as follows: Ca, Cd, Cu, Fe, K, Mg, Na, P and Zn by inductively coupled plasma atomic emission spectrometry; total Hg (T-Hg) and inorganic Hg (I-Hg) by cold vapour atomic absorption spectrometry; methyl Hg (MeHg) by gas chromatography; and Se by fluorometry. A significantly positive correlation between Se and T-Hg was observed in kidney, liver, heart and spleen. The T-Hg/Se molar ratio was less than 1 in all the organs examined. The correlation between Zn and Cd was significant in liver and kidney. Multiple regression analyses using Se as a dependent and I-Hg, MeHg, Zn, Cd, Cu as independent variables were conducted on each organ. Inorganic Hg was a significant independent variable in kidney, whereas in liver and spleen it was MeHg. Cadmium was significant in explaining the variations in Se in liver and kidney medulla, indicating Cd-Se co-accumulation in humans.

Adolescent↗
PubMed1990

On the mode of cardioprotection produced by a new bradycardic agent, FR 76830, during ischaemia and after reperfusion in the isolated perfused rat heart: a 31P-NMR study.

STUDY OBJECTIVE: The aim was to investigate the effects of a newly synthesised bradycardiac agent, FR 76830, on cardiac mechanical function and metabolism during ischaemia and reperfusion. DESIGN: FR 76830 and diltiazem were infused during 15 min before ischaemia. Hearts were then subjected to ischaemia (40 min) followed by reperfusion (40 min). High energy phosphate compounds and myocardial pH were assessed by 31P-NMR. The effects of bradycardia induced by FR 76830 before induction of ischaemia on the metabolic derangement resulting from ischaemia and on functional and metabolic recovery after reperfusion were examined in comparison with diltiazem. EXPERIMENTAL MATERIAL: Male Wistar rats (about 250 g) were used. MEASUREMENTS AND MAIN RESULTS: FR 76830 and diltiazem produced a dose dependent decrease in heart rate before ischaemia. However, the decrease in the double product (heart rate x left ventricular pressure) was observed only with diltiazem. Both FR 76830 and diltiazem attenuated the fall in myocardial pH during early ischaemia and improved the level of ATP during late ischaemia. Diltiazem also produced an improvement in myocardial acidosis during late ischaemia and in the level of ATP during early ischaemia. CONCLUSIONS: The importance of bradycardia in protection of the myocardial cells during early ischaemia and in preservation of ATP content during late ischaemia and after reperfusion was shown. However, to produce an improvement in myocardial pH during late ischaemia a decrease in the double product is needed.

Adenosine Triphosphate↗