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T Kosaka

Publications and source records attributed to T Kosaka.

At least 37 records · Page 2Linked to original sources

Comparison of emptying between gastric and colonic conduits following esophagectomy.

The emptying of gastric and colonic conduits following esophagectomy was evaluated. Ten consecutive patients who underwent esophagectomy for malignant diseases were divided into two groups as follows: Group I which consisted of 5 patients who underwent pyloroplasty and in whom the gastric greater curvature was used for reconstruction; and Group II which consisted of 5 patients in whom the colonic conduit was used because of previous gastrectomy. The conduits were placed in the retrosternal spaces in all the patients. The radiopaque markers swallowing test and digestive tract scintigraphy were performed to evaluate emptying two months after surgery. The radiopaque markers swallowing test demonstrated that marker rings quickly disappeared from the gastric conduits but remained in the colonic conduits for as long as three hours. Digestive tract scintigraphy demonstrated that there was no significant difference in the 60-minute clearance rate of 99mTc-DTPA from the conduits between the two groups. The results suggested that tiny food fragments remained in the haustral pockets of the colonic conduits, which may be a disadvantage of these conduits.

Aged↗

Structure of intraglomerular dendritic tufts of mitral cells and their contacts with olfactory nerve terminals and calbindin-immunoreactive type 2 periglomerular neurons.

Intraglomerular dendritic tufts of Golgi-impregnated and biotinylated dextran amine (BDA)-labeled mitral cells in the rat main olfactory bulb were analyzed in detail. In particular, the relationships of BDA-labeled tufts with olfactory nerve (ON) terminals and processes of calbindin D-28K-immunoreactive (CB-IR) cells were investigated with confocal laser-scanning light microscopic (CLSM) and electron microscopic (EM) analyses. CB-IR cells were type 2 periglomerular cells that restricted their processes in the ON-free (non-ON) zone of the glomerulus and received few synapses from ON terminals. The mitral tufts varied in complexity, but individual branches were rather simple, smooth processes that bore some branchlets and spines and extended more or less in a straight line or a gentle curve rather than winding tortuously within glomeruli as though they did not consider the compartmental organization, which consisted of ON and non-ON zones that interdigitated in a complex manner with one another. Conventional EM analysis revealed that both thin and thick, presumed proximal branches of mitral/tufted cell dendritic tufts received asymmetrical synapses from ON terminals. Correlated CLSM-EM analysis confirmed direct contacts between the BDA- and CB-labeled processes detected in the CLSM examinations, and synapses were recognized at some of those sites. Furthermore, ON terminals and CB-IR processes were distributed on both proximal and distal dendritic branches in a more or less mosaic pattern. These findings revealed that, on the mitral dendritic tufts, ON terminals and processes of type 2 periglomerular neurons were not clearly segregated proximodistally but, rather, were arranged in a mosaic pattern, which may be important in fine tuning the output from individual glomeruli.

Animals↗

Growth kinetics of algal populations exsymbiotic from Paramecium bursaria by flow cytometry measurements.

BACKGROUND: The ciliate Paramecium bursaria normally exists as a green paramecium system because each animal cell carries several hundred, unicellular, green, algal cells in its cytoplasm. One of the remarkable and poorly understood pecularities of this system is the steady state in the number of algae per protozoan cell. A major point in the study of mechanisms governing the persistence of symbiont numbers is adequate understanding of the algal life cycle. METHODS: Asynchronously growing cell populations of several algal strains (SA-1, SA-3, and SA-9) exsymbiotic from P. bursaria were characterized by flow cytometry. Algal endogenous chlorophyll and DNA contents were monitored to analyze cell growth kinetics at logarithmic and stationary culture phases. Cell sorting visualized the morphology of algae corresponding to the hyperhaploid (2C and 4C) DNA peaks. RESULTS: Cell-division cycle-dependent changes in chlorophyll and DNA content distributions were most dramatic in logarithmically growing algal populations (an increase in the number of S-phase cells and cells with more chlorophyll), which are thought to be associated with accelerated DNA and chlorophyll metabolism in log-phase algal cultures. Upon reaching the stationary phase of growth, algal populations distinctly showed, in addition to one haploid (1C) DNA peak, two hyperhaploid peaks (2C and 4C) corresponding mainly to cells with two and four nuclei, respectively. CONCLUSIONS: Growth characteristics of algae exsymbiotic from P. bursaria monitored by flow cytometry provide valuable information for the analysis of the algal life cycle, which is important for understanding the regulation mechanisms of symbiont numbers.

Animals↗

Bacterial infection promotes colon tumorigenesis in Apc(Min/+) mice.

The Min mouse, which has a germ line mutation in 1 allele of the Apc tumor suppressor gene, is a model for the early steps in human colorectal cancer. Helicobacter pylori infection, a known risk factor for gastric cancer in humans, causes chronic inflammation and increased epithelial cell proliferation in the stomach. Infection with the bacterium Citrobacter rodentium is known to increase epithelial cell proliferation and to promote chemically initiated tumors in the colon of mice. Min mice infected with C. rodentium at 1 month of age were found to have a 4-fold increase in the number of colonic adenomas at 6 months of age, compared with uninfected Min mice. Most of the colonic adenomas in the infected Min mice were in the distal colon, where C. rodentium-induced hyperplasia occurs. These data demonstrate that bacterial infection promotes colon tumor formation in genetically susceptible mice.

Adenoma↗

Identification of human liver diacetyl reductases by nano-liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry.

Several forms of diacetyl-reducing enzyme were found to exist in the human liver cytosol. Three (DAR-2, DAR-5, and DAR-7) of them were purified as a single band on SDS-PAGE by a combination of a few kinds of column chromatographies. The in-gel tryptic digests of the purified enzymes were analyzed by nano-liquid chromatography (LC)/Fourier transform ion cyclotron resonance mass spectrometry (FT ICR MS), which provided peptide masses at a ppm-level accuracy. The enzymes, DAR-2, DAR-5, and DAR-7, were identified as alcohol dehydrogenase beta subunit (ADH2), carbonyl reductase (CBR1), and aldehyde reductase (AKR1A1), respectively, by peptide mass fingerprinting. In addition, an alternating-scan acquisition of nano-LC/FT ICR mass spectra, i.e., switching of normal acquisition conditions and in-source fragmentation conditions scan by scan, provided sets of parent and fragment ion masses of many of the tryptic peptides in a single LC/MS run. The peptide sequence-tag information at the ppm-level accuracy was used to further confirm the protein identities. It was demonstrated that nano-LC/FT ICR MS can be used for rigorous protein identification at a subpicomole level as an alternative technique to nano-LC/MS/MS.

Acetoin Dehydrogenase↗

Morphometric multivariate analysis of GABAergic neurons containing calretinin and neuronal nitric oxide synthase in the mouse hippocampus.

Several studies reported the morphology of calretinin-positive (CR+) neurons and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) labeled or neuronal nitric oxide synthase-positive (nNOS+) neurons in the rodent hippocampus, where these neurons showed similar morphological features. In addition, a previous study reported the frequent colocalization of CR and NADPH-d in the rat hippocampus. In this study, we aimed to examine whether CR+ neurons and nNOS+ neurons belong to a same morphological subpopulation of GABAergic neurons in the mouse hippocampus. Neurons were immunocytochemically classified into three groups, i.e., CR+/nNOS-, CR-/nNOS+ and CR+/nNOS+ groups. The present morphometric analysis was performed in the mouse Ammon's horn, because CR+/nNOS+ neurons were rarely found in the mouse dentate gyrus. We selected three morphometric parameters, i.e., soma area, soma form factor (FF) and number of primary dendrites. Dunnett's post-hoc analysis revealed that soma area, soma FF and number of primary dendrites were significantly larger in CR-/nNOS+ group than in CR+/nNOS- and CR+/nNOS+ groups. The morphometric data of CR+/nNOS+ group were quite similar to those of CR+/nNOS- group. The morphometric multivariate logistic regression analysis revealed that these three morphometric parameters were independent significant variables to discriminate between CR+/nNOS- and CR-/nNOS+ groups, and the majority of CR+/nNOS- and CR-/nNOS+ groups were correctly classified from the morphometric features. The present results clearly indicate that CR+/nNOS- neurons and CR-/nNOS+ neurons belong to different morphological subpopulations, and lead us to speculate that they might play different functional roles in the hippocampal circuit. The further application of morphometric multivariate analysis would be valuable to understand the functional roles of chemically defined neurons in the various brain regions.

Animals↗

Isolated airway exposure to toluene diisocyanate results in skin sensitization.

Toluene diisocyanate (TDI), a highly reactive industrial chemical is a leading cause of occupational asthma in westernized countries. It has also been reported to be a skin sensitizer in mice and guinea pigs although instances of skin sensitivity in humans are rare. It is uncertain if skin-contact is necessary to initiate the dermal sensitization. This study sought to determine if exclusive airway exposure to TDI could result in skin sensitivity. A group of guinea pigs was administered 50 microl of 0.6% TDI intratracheally (it.), another group received intranasal (in.) application of 0.6, 1.2, or 1.8% TDI. Eighty percent (4/5) of the it.-dosed animals, and 92% (11/12) of in.-dosed animals exhibited skin sensitivity. None of 14 control animals gave a positive reaction to patch challenge with TDI. These findings indicate that exclusive exposure of the airways to TDI can result in skin sensitivity and suggest that such events may be possible in TDI workers and should be considered in all workers exposed via the airways to chemical sensitizers.

Administration, Inhalation↗

Nidus and tasseled cell: distinctive neuronal organization of the main olfactory bulb of the laboratory musk shrew (Suncus murinus).

We revealed the structural features of particular synaptic regions, nidi, and newly found neurons, tasseled cells, in the main olfactory bulb (MOB) of the laboratory musk shrew (Suncus murinus). Nidi were intensely immunoreactive for glutamic acid decarboxylase (GAD) and calbindin D28k (CB), were 30-80 microm in diameter, and were located beneath glomeruli, appearing to make glomerulus-nidus unit-like complexes. In contrast to glomeruli, they contained few or no olfactory nerves. Nidi were distributed throughout the whole MOB and made a distinctive layer, nidal layer. Tasseled cells were located in the mitral cell layer and in the middle of the external plexiform layer (EPL) and extended single primary dendrites to the nidus, where their small tuft-like complicated branches intermingled with processes of perinidal cells surrounding nidi. Primary dendrites of mitral/tufted cells also penetrated nidi but passed to glomeruli. In the outer half of the EPL, columnar structures were seen, where CB- and GAD-positive elements appeared to associate with bundles of cylindrical dendrites of presumed mitral/tufted and tasseled cells. By electron microscopic examinations, nidi were confirmed to be particular synaptic areas where GAD-positive processes made symmetrical synapses to GAD-negative presumed tasseled and mitral/tufted cell dendrites and received asymmetrical synapses from the latter. Retrograde tracings revealed that tasseled cells, in addition to mitral/tufted cells, projected their axons to the lateral olfactory tract, indicating that there were two parallel projection systems in the shrew MOB, which might interact with each other via various types of gamma-aminobutyric acid (GABA)ergic interneurons. The present study clearly showed that the neuronal organization of the shrew MOB was distinctly different from that in rodents.

Animals↗

Association of intermediate T cell receptor cells, mainly their NK1.1(-) subset, with protection from malaria.

Mice were infected with Plasmodium (P.) yoelii blood-stage parasites. Both the liver and spleen were the sites of inflammation during malarial infection at the beginning of day 7. The major expanding cells were found to be NK1.1(-) intermediate alphabetaTCR (alphabetaTCR(int)) in the liver and spleen, although the population of NK1.1(+) alphabetaTCR(int) cells remained constant or slightly increased. These TCR(int) cells are of extrathymic origin or are generated by an alternative intrathymic pathway and are distinguished from conventional T cells of thymic origin. During malarial infection, the population of conventional T cells did not increase at all. TCR(int) cells purified from the liver of mice which had recovered from P. yoelii infection protected mice from malaria when they were transferred into 6.5-Gy-irradiated mice. Interestingly, the immunity against malaria seemed to disappear as a function of time after recovery, namely, mice which had recovered from malaria 1 year previously again became susceptible to malarial infection. The present results suggest that TCR(int) cells are intimately associated with protection against malarial infection and, therefore, that mice which had recovered from malaria 1 year previously lost such immunity.

Animals↗

Structural features of mossy cells in the hamster dentate gyrus, with special reference to somatic thorny excrescences.

We have recently revealed that large multipolar neurons, presumed mossy cells in the hamster dentate gyrus (DG), were calretinin (CR)-immunoreactive (IR) at the ventral level, although these neurons were CR-negative at the dorsal level. In the present study, we confirmed this identification with several methods and analyzed structural features of hamster mossy cells in detail. Golgi impregnationi and intracellular Lucifer yellow labeling studies revealed that mossy cells in the hamster dentate hilus had extraordinarily prominent thorny excrescences on their somata as well as on their proximal dendrites. Mossy cells exhibited dorsoventral differences in their structural features; proximal dendrites of single mossy cells were fewer, and thorny excrescences were larger and more complicated at the dorsal level than at the ventral level. Electron microscopic serial section three-dimensional reconstructions revealed that somatic thorny excrescences consisted of large and complicated spines, which received numerous asymmetrical synapses from mossy fiber terminals. In addition, our confocal laser scanning microscopic observations also revealed many glutamic acid decarboxylase-immunoreactive punctae abutting the mossy cell somata and dendrites. Our present and previous observations revealed the structural features of hamster mossy cells and their differences along the dorsoventral axis and further indicated that mossy cells were prominently different in their chemical and morphological features among species.

Animals↗

Serum platelet-activating factor acetylhydrolase (PAF-AH) activity in more than 3000 healthy Japanese.

BACKGROUND: A spectrophotometric assay for platelet-activating factor acetylhydrolase (PAF-AH) activity differs from the radioisotopic assay in its value because of a difference in substrate specificity. The spectrophotometric assay is more precise than the radioisotopic assay, providing information that is not clear with the radioisotopic assay. METHODS: We measured the serum PAF-AH activity in 3106 healthy Japanese, utilizing the spectrophotometric assay with an Hitachi 7170 automatic analyzer. We also measured the serum PAF-AH activity in 18 healthy volunteers to investigate the effect of diet and the change in activity in a day and over 6 weeks. Changes were examined at 0 (day 1), 1, 2, 4 and 6 weeks. RESULTS: The mean value for females was significantly lower than that of males at the 5% level and both male and female activity had a tendency to increase with advancing age. It is known that the PAF-AH is primarily associated with LDL in blood and the PAF-AH activity correlated with the total cholesterol (r=0.52, n=126) and the LDL cholesterol (r=0.60, n=126) concentrations. In the diet study, there was no observable effect on activity. No difference in PAF-AH activity was observed between serum and plasma sample types. The serum PAF-AH activity was stable at 7 degrees C for at least 7 days and at -20 degrees C for at least 2 months. CONCLUSIONS: The serum PAF-AH activity in women was lower than in men until the menopausal age was reached. We could use not only fresh fasting serum, but also plasma sample, non-fasting sample and stored sample to estimate the PAF-AH activity.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

Post-immunisation gastritis and Helicobacter infection in the mouse: a long term study.

BACKGROUND AND AIMS: Helicobacter pylori is a major cause of peptic ulcers and gastric cancer. Vaccine development is progressing but there is concern that immunisation may exacerbate Helicobacter induced gastritis: prophylactic immunisation followed by challenge with H felis or H pylori can induce a more severe gastritis in mice than seen with infection alone. The aim of this study was to investigate the relationship between immunity to Helicobacter infection and post-immunisation gastritis. METHODS: (1) C57BL/6 mice were prophylactically immunised before challenge with either H felis or H pylori. Histopathology and colonisation were assessed one month post-challenge. (2) C57BL/6 mice were prophylactically immunised against H felis infection and gastritis assessed up to 18 months post-challenge. RESULTS: Prophylactic immunisation induced a reduction in bacterial colonisation following H felis challenge which was associated with increased severity of active gastritis with neutrophil infiltration and atrophy. However, immunised mice challenged with H pylori SS1 had little evidence of pathology. Long term follow up showed that post-immunisation gastritis was evident at three months. However, from six months onwards, although immunised/challenged mice still developed gastritis, there was no significant difference between inflammation in these mice and infected controls. Post-immunisation gastritis was not associated with the serum antibody response. Immunisation prevented the formation of secondary lymphoid aggregates in the gastric tissue. CONCLUSION: The H felis mouse model of post-immunisation gastritis is the most extreme example of this type of pathology. We have shown in this model that post-immunisation gastritis is a transient event which does not produce long term exacerbation of pathology.

Analysis of Variance↗

Colocalization of parvalbumin and somatostatin-like immunoreactivity in the mouse hippocampus: quantitative analysis with optical dissector.

The colocalization of parvalbumin (PV) and somatostatin (SS)-like immunoreactivity was studied quantitatively in the mouse hippocampus, with particular reference to their areal and dorsoventral differences. The optical disector method was applied by using a confocal laser scanning microscope with immunofluorescent double-labeling. In the present study, we found a particular subpopulation of hippocampal nonprincipal neurons that contained both PV and SS-like immunoreactivity, i.e., PV-immunoreactive (IR)/SS-like immunoreactive (LIR) neurons. In the CA1 region, PV-IR/SS-LIR neurons were restricted to the stratum oriens (SO). In the CA3 region, they were scattered in the SO, stratum pyramidale (SP), and stratum radiatum (SR). However, they were rarely seen in the dentate gyrus (DG). The proportion of PV-IR/SS-LIR neurons in the PV-IR neurons or SS-LIR neurons was about 10% in the CA1 region, 15-30% in the CA3 region, 0-5% in the DG, and 10-20% in total. Laminar analysis revealed that the proportions of PV-IR/SS-LIR neurons in the PV-IR neurons were high in the SO (about 25%) of the CA1 region, and in the SO (about 50%) and SR (30-45%) of the CA3 region. The proportion of PV-IR/SS-LIR neurons in the SS-LIR neurons was low in the SO of the CA1 region (about 10%), but high in the SO (35-65%) and SR (35-45%) of the CA3 region. Morphologically, medium-sized horizontal fusiform and multipolar PV-IR/SS-LIR neurons were frequently observed, and they showed weak immunoreactivity for PV. Large-sized vertical bitufted and triangular PV-IR neurons lacked SS-like immunoreactivity, and most of them showed moderate to intense immunoreactivity for PV. In addition, we provide direct evidence that some PV-IR/SS-LIR neurons projected to the medial septum by using retrograde labeling with Fluoro-Gold injection. These observations indicate that PV-IR/SS-LIR neurons constitute a particular subpopulation of hippocampal nonprincipal neurons.

Animals↗

Flow cytometry as a strategy to study the endosymbiosis of algae in Paramecium bursaria.

BACKGROUND: The stable symbiotic association between Paramecium bursaria and algae is of interest to study such mechanisms in biology as recognition, specificity, infection, and regulation. The combination of algae-free strains of P. bursaria, which have been recently established by treating their stocks of green paramecia with herbicide paraquat (Hosoya et al.: Zool Sci 12: 807-810, 1995), with the cloned symbiotic algae isolated from P. bursaria (Nishihara et al.: Protoplasma 203: 91-99, 1998), provides an excellent clue to gain fundamental understanding of these phenomena. METHODS: Flow cytometry and light microscopy have been employed to characterize the algal cells after they have been released from the paramecia by ultrasonic treatment. Algal optical properties such as light scattering and endogenous chlorophyll fluorescence intensity have been monitored for symbiotic and free-living strains, and strains at stages of interaction with a host. RESULTS: Neither algal morphology nor chlorophyll content has been found to be altered by sonication of green paramecia. This fact allows to interpret in adequate degree changes in the optical properties of symbiont that just has been released from the association with a host (decreased forward light scatter and chlorophyll fluorescence signals). Optical characterization of both symbiotic and free-living algal strains with respect to their ability to establish symbioses with P. bursaria showed that chlorophyll content per cell volume seems to be a valuable factor for predicting a favorable symbiotic relationship between P. bursaria and algae. CONCLUSIONS: Flow cytometry combined with algae-free paramecia and cloned symbiotic algae identifies algal populations that may be recognized by host cells for the establishment of symbioses.

Animals↗

Biologically active oligodeoxyribonucleotides. Part 12: N2-methylation of 2'-deoxyguanosines enhances stability of parallel G-quadruplex and anti-HIV-1 activity.

2'-Deoxyguanosine residues of a 3',5'-end-modified hexadeoxyribonucleotide (R-95288) with anti-HIV-1 activity were substituted with N2-methyl-2'-deoxyguanosine (m2dG). These modified oligodeoxyribonucleotides (ODNs) showed a 2-fold higher activity than R-95288. Also, the CD spectra of these ODNs indicated that the m2dG modification stabilized the tertiary structure of the G-quadruplex.

Anti-HIV Agents↗