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Biomedical subjects

S Kato

Publications and source records attributed to S Kato.

At least 991 records · Page 55Linked to original sources
PubMed1993

Enhancement of DNA polymerase beta activity in the pituitary gland by hormonal feedback.

The activity of DNA polymerase beta (beta-enzyme) in bovine and rat pituitary glands was remarkably higher in the anterior than in the posterior lobe. In sucrose gradient centrifugation, the activity in the anterior lobe of the bovine pituitary gland appeared at the sedimentation constant, 3.3 S, while that of rat pituitary gland appeared at 3.3 S, 7.3 S and 12 S, respectively. The activity in each fraction increased in the anterior lobes of rat pituitaries that were stimulated to release TSH by decreased thyroid hormone levels induced by an antithyroid drug. These results suggest that the activity of the beta-enzyme is high in the cells of the anterior lobe which are hyperfunctioned to produce pituitary thyreotrophic hormone and may be controlled by hormonal feedback regulation.

Animals↗
PubMed1993

Capacity of goat epididymal spermatozoa to undergo the acrosome reaction and subsequent fusion with the egg plasma membrane.

The capacity to undergo the acrosome reaction and subsequent fusion with the egg plasma membrane was examined in goat epididymal spermatozoa. Spermatozoa from the proximal and distal caput and distal cauda were preincubated in a sealed glass tube for induction of the acrosome reaction, and their viability, acrosome morphology and penetrability into zona-free hamster eggs were determined. A simplified triple-stain technique revealed that most of the preincubated live spermatozoa in the samples from the distal caput and distal cauda epididymides underwent morphological changes that indicated the occurrence of the acrosome reaction. Electron microscopic examination revealed that the outer acrosomal membrane of many spermatozoa in these samples showed fusion at multiple sites to the plasma membrane. However, the rates of acrosome-reacted cells in the proximal caput spermatozoa were still lower. The sperm penetration assay demonstrated that the penetration rates of distal caput and distal cauda spermatozoa preincubated for 2 h were 93% and 74% respectively, whereas proximal caput spermatozoa scarcely penetrated into eggs. These results indicate that increasing numbers of goat spermatozoa improve in the functions related to the acrosome reaction and subsequent fusion with the egg plasma membrane during their transit through the caput epididymidis.

Acrosome↗
PubMed1993

Heterogeneity of hepatic acetaldehyde adducts in guinea-pigs after chronic ethanol administration: an immunohistochemical analysis with monoclonal and polyclonal antibodies against acetaldehyde-modified protein epitopes.

The formation of acetaldehyde (AcH) adducts was immunohistochemically demonstrated in the livers of experimental animals after chronic ethanol consumption. Recently, we established a hybridoma producing monoclonal antibody against the adduct. Although the polyclonal antibody obtained from a rabbit immunized with adducts had affinities for AcH adducts produced with 20 microM, 1 mM and 10 mM of AcH, the monoclonal antibody could recognize only those produced with 1 and 10 mM of AcH, suggesting that there is a difference of antigenicity between the adducts formed with a high concentration of AcH and those modified with a low concentration of AcH. AcH adducts in the liver of guinea-pigs fed ethanol for 90 days were detected by immunohistochemical staining with the polyclonal and monoclonal antibodies. The staining of liver specimens with polyclonal antibody was observed around both the portal and perivenular areas, whereas the reactions to monoclonal antibody were localized only in the perivenular area. These data suggest that AcH adducts are able to be formed around both portal and perivenular areas in the liver and that the perivenular area might be exposed to a higher concentration of AcH than the portal area after ethanol intake.

Acetaldehyde↗
PubMed1993

7-Alkyldeoxyguanosine adduct detection by two-step HPLC and the 32P-postlabeling assay.

7-Alkyldeoxyguanosine DNA adducts may be a marker for some N-nitroso compound exposures and subsequent human cancer risk. A sensitive and highly specific assay for the detection of 7-methyl-2'-deoxyguanosine-3'-monophosphate (7-methyldGp) and 7-ethyl-2'-deoxyguanosine-3'-monophosphate (7-ethyldGp) has been developed by combining two different HPLC purification steps with the 32P-postlabeling assay. We previously reported that ion-pair reverse-phase (IP) chromatography coupled with the 32P-postlabeling assay detects 7-methyldGp in human lung, but have found that other nucleotides and unknown adducts co-elute. Thus, weak anion exchange (AE) HPLC was added in tandem with IP HPLC prior to the 32P-postlabeling assay. 2'-Deoxyguanosine-3'-monophosphate (dGp) is incorporated into the assay as an internal standard for the assessment of enzyme labeling efficiency and adduct recovery. The methodology was validated using radiolabeled DNA and liquid scintillation counting, which accounts for adduct loss from enzymatic digestion to detection. Levels of 7-ethyldGp also were correlated with accelerator mass spectrometry. The overall adduct recovery with this method was 58% for 7-methyldGp and 98% for 7-ethyldGp. The detection limit for both assays using 100 micrograms of DNA was one adduct in 10(8) unmodified dGp. 7-MethyldGp and 7-ethyldGp levels were determined in ten human lung samples at levels of 1.4-5.4 and 0.6-3.1 adducts per 10(7) dGp respectively, and in five human lymphocyte samples at levels of 5.0-8.3 and 0.3-1.4 adducts per 10(7) dGp respectively. Combining the two HPLC purification steps and the 32P-postlabeling assay attains chemical specificity, retains sufficient quantitative sensitivity and should be useful in human biomonitoring studies.

Animals↗
PubMed1993

Filament-forming domain of carp dorsal myosin rod.

Substructure of the myosin rod and its correlation to the filament formation were investigated by using fish myosin rod. It was found that fish rod contains a unique chymotrypsin susceptible site, 40 kDa from the COOH-terminus or 20 kDa downstream from the subfragment-2/light meromyosin junction (S-2/LMM junction). Cleavage at this new site produced subfragment-2 possessing 95 kDa subunit (95k S-2) and light meromyosin possessing 40 kDa subunit (40k LMM). The latter is the shortest unit ever reported to exhibit filament formation. Moreover, the 40k LMM was able to form filaments independently of the presence of Mg2+, while filament formation of rod and ordinary LMM (70k LMM) was promoted by Mg2+ addition. These results indicated that the Mg2+ binding sites are present within the NH2-terminal 20 kDa region of the 70k LMM. We concluded that the COOH-terminal 40 kDa portion of rod is responsible for the self-assembly ability of myosin, while the NH2-terminal 20 kDa region of the 70k LMM is the regulatory domain for thick filament formation through Mg(2+)-binding.

Animals↗
PubMed1993

Phylogenetic diversity of phytopathogenic mycoplasmalike organisms.

By using specific primers, the 16S rRNA genes of Japanese mycoplasmalike organisms (MLOs) were amplified by polymerase chain reactions from MLO-enriched fractions of plants infected with each of six different MLOs. Each of the polymerase chain reaction fragments (length, 1,370 nucleotides) was directly sequenced in both strands by using 17 oligonucleotide primers. A phylogenetic tree constructed by using the sequence data showed that these Japanese MLOs are phylogenetically diverse microorganisms that fall into three groups, group I (onion yellows, tomato yellows, mulberry dwarf, and paulownia witches' broom MLOs), group II (tsuwabuki witches' broom MLO), and group III (rice yellow dwarf MLO). A high level of sequence homology (99%) between the Oenothera hookeri MLO and the severe strain of the western aster yellows MLO on the one hand and group I MLOs on the other indicates that the O. hookeri MLO and the severe strain of the western aster yellows MLO belong to group I and suggests that these MLOs, isolated from two geographically separated locations, descended from a very similar ancestor. Although group I contains phylogenetically identical MLOs, the organisms are transmitted by diverse insect vectors. The three MLO groups are more closely related to Acholeplasma laidlawii than to Mycoplasma gallisepticum. Thus, although MLOs are phylogenetically diverse, they are evolutionarily distant from other mollicutes. These data, together with other information (including phylogenetic relationships, vector specificity, plant-pathogenic properties, and habitat in plant phloem sieve tubes), suggest that MLOs could be classified into at least three phylogenetic groups (groups I through III).

Acholeplasma↗
PubMed1993

Diminution of dopaminergic neurons in the substantia nigra of sporadic amyotrophic lateral sclerosis.

The substantia nigra was examined immunohistochemically using the antibody to tyrosine hydroxylase in 15 patients with sporadic amyotrophic lateral sclerosis (ALS). The number of dopaminergic neurons was diminished in the substantia nigra of seven cases. The diminution was not related to the age, duration of the illness or use of respirators. Supranuclear ophthalmoplegia developed in four and dementia in three out of seven patients with reduction of nigral dopaminergic neurons. In addition, five out of the seven patients developed respiratory failure within 2 years after the onset of the illness. The nigral dopaminergic system may be involved in rapidly progressive ALS patients with supranuclear ophthalmoplegia and/or dementia.

Aged↗
PubMed1993

Comparative study on the expression of stress-response protein (srp) 72, srp 27, alpha B-crystallin and ubiquitin in brain tumours. An immunohistochemical investigation.

This immunohistochemical study compares the expression of stress-response (heat-shock) protein (srp) 72, srp 27, alpha B-crystallin and ubiquitin in 86 primary human brain tumours and 21 carcinoma metastases to the central nervous system. Normal brain tissues were included for control purposes. Serial sections of formalin-fixed, paraffin-embedded tissues were used. Most meningiomas (17/23), glioblastomas (11/12) and breast carcinoma metastases (9/10) and some astrocytomas (7/13), pituitary tumours (4/9) and lung cancer metastases (5/11) had tumour cells that reacted with one or more of the antibodies used. Around 43% of the meningiomas and 25% of the glioblastomas expressed srp 72 only. Sole expression of srp 27, alpha B-crystallin or ubiquitin was seen in several tumours. Some meningiomas (3/23) and breast cancer metastases (4/10) co-expressed srp 72 and srp 27, and 1/3 of the glioblastomas co-expressed srp 27 and alpha B-crystallin. We conclude that primary and metastatic tumours of the brain produce stress-related proteins and that certain tumours concurrently express two or more srp's.

Brain Neoplasms↗
PubMed1993

Growth and growth hormone secretion in children after bone marrow transplantation.

Long-term sequelae of bone marrow transplantation (BMT) are a major concern among long-term survivors since the procedure has been considerably developed over the past decade. In this study, linear growth and growth hormone (GH) secretion were evaluated in 25 children (14 males and 11 females) with various neoplastic or non-neoplastic hematological disorders who had survived for more than 3 years after BMT. Impaired linear growth after BMT, as defined by a change in height standard deviation score (SDS) by more than -1.0 SD, was observed in 14 patients (56%). Four children showed severe growth suppression with a decrease in SD score by more than 2.0, and 10 exhibited a moderate reduction by between 1.0 and 2.0 SD. A recovery of normal height velocity was observed in those who had received BMT at a younger age. The type of disease, a difference in preconditioning regimen, the presence of chronic graft-versus-host disease or a GH secretory capacity 1 year after BMT were not contributing factors for impaired growth. A serial examination of GH secretion with insulin-induced hypoglycemia demonstrated that poor GH secretion was not necessarily a prerequisite for impaired growth. These results indicate that the secretory status of GH does not predict the future growth pattern of children who received BMT.

Adolescent↗
PubMed1993

Inflammatory esophagogastric polyp and fold in an adolescent.

The case of a 13 year old boy with an inflammatory esophagogastric polyp and ulcerative colitis is described. Endoscopy revealed a typical polyp and gastric fold complex at the esophagogastric junction and a hiatal hernia. Histology of a biopsy specimen confirmed an inflammatory polyp covered by hyperplastic squamous and gastric foveolar epithelium. Continuous 24 hour esophageal manometry suggested gastroesophageal reflux, which may be related to the pathogenesis of the lesion. Follow-up endoscopy showed marked regression of the polyp with medication for reflux esophagitis. This clinical entity is rare in childhood and adolescence, and the manifestations may not be readily recognized. Therefore, endoscopic biopsy is important in children with esophageal polyps. However, polypectomy is unnecessary except when malignancy is suspected or when symptoms persist.

Adolescent↗
PubMed1993

Endoscopic ultrasonography in a child with chronic pancreatitis.

In a case with chronic pancreatitis and pseudocysts related to muscular cytochrome-c oxidase deficiency, endoscopic ultrasonography (EUS) was performed to morphologically examine the pancreas for features that may have been missed by abdominal computed tomography and pancreatography. Conventional abdominal sonography had failed to show valuable diagnostic information of chronic pancreatitis in this case. EUS demonstrated several new findings. Parenchymal atrophy was remarkable, especially in the pancreatic tail, and a dilated pancreatic main or branch duct was clearly found in the region. Moreover, pancreatic stones in the main duct were also distinctly proved. EUS may become a useful new diagnostic method in pediatric gastroenterology, especially when sufficient findings are not obtained by conventional imaging techniques. However, an ultrasonographic endoscope with a shorter rigid portion and smaller caliber should be developed for pediatric patients.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1993

Periodic fluctuations in pancreatic secretion and duodenal motility investigated in neonatal calves.

To clarify the relative timing of clinical changes in duodenal motility and pancreatic secretion in newborn calves, we recorded duodenal electrical and mechanical activity and analysed pancreatic secretion and migrating myoelectric complex (MMC). In eight calves integrated recordings were derived from sites near the duodenal bulb and pancreatic accessory duct orifice, and pancreatic juice was sampled after an overnight fast, after a feed, and during reversible cold vagal blockade. Peak secretion coincided with duodenal irregular spiking activity and the nadir with absence of spiking. Feeding elicited electrical and mechanical hyperactivity in the duodenum, dissipated the MMC temporarily, and dramatically increased the juice volume and bicarbonate and protein outputs. Periodic fluctuations in secretion started shortly after a feed, as did recovery of the duodenal myoelectric complexes. Cold vagal blockade reversibly disrupted the synchronous changes in duodenal motility and pancreatic secretory activity, though the close association was not totally obliterated. In milk-fed calves interdigestive pancreatic secretion apparently rises and falls in phase with migrating myoelectric complexes of the proximal duodenum and the vagus is largely, though not exclusively, responsible for co-ordinating these changes.

Animals↗
PubMed1993

Mycoplasmalike organisms (MLOs) and distinguish them from other MLOs.

DNA of 10 lines of rice yellow dwarf (RYD) mycoplasmalike organisms (MLOs) from Japan, the Phillippines, and Thailand hybridized with four probes containing chromosomal and six probes containing extrachromosomal DNA of a Tochigi (Japan) line of RYD MLO. One chromosomal probe (RYD9) and all six extrachromosomal probes hybridized with various other MLOs (sugarcane white leaf, onion yellows, cineraria witches'-broom, Japanese hornwort witches'-broom, water dropwort wiches'-broom, gentian witches'-broom, udo dwarf, tsuwabuki witches'-broom, pelargonium witches's-broom, peach western-X, and pear decline). DNA from the culturable mollicutes Spiroplasma kunkelii, Spiroplasma citri, Mycoplasma hominis, and Mycoplasma orale did not hybridize with RYD MLO probes. The extrachromosomal DNAs hybridizing with the probes showed variations in electrophoretic behavior.

Base Sequence↗
PubMed1993

Induction of gelatinolytic neutral proteinase secretion by lipid peroxide in cultured mesangial cells.

To investigate whether lipid peroxides in tissue and/or blood play an important role in the injury to mesangial cells and glomerular structural proteins, we studied the effect of linoleic acid hydroperoxide (LHO) on mesangial cells cultured from rat kidneys. When 1.0-3.0 nmol/ml of LHO were added to the culture, the production of 70-kDa gelatinolytic neutral proteinase by mesangial cells was enhanced without morphological damage. The production of the enzyme, however, was inhibited by an addition of 4.0 or 5.0 nmol/ml of LHO and a microscopic examination also demonstrated marked injury to mesangial cells in the presence of these concentrations of LHO. These data suggest that there is a possibility that increased lipid peroxides in tissue and/or blood play a role in the injury to mesangial cells and glomerular structural proteins leading to mesangiopathy.

Animals↗
PubMed1993

Further differentiation of 2'- and 4'-chloroflavones as inducers of hepatic microsomal monooxygenases in rats.

2'-Chloroflavone (CF) and 4'-CF were studied as inducers of cytochrome P-450-mediated monooxygenases in rat hepatic microsomes by comparison with phenobarbital (PB) and 3-methylcholanthrene (MC). As a result of interaction with the substrate 7-ethoxycoumarin (7-EC), 2'-CF-induced microsomes showed a difference spectrum different from usual type I, whereas 4'-CF-induced microsomes showed a typical type I spectrum. 2'-CF-induced microsomes increased the Vmax of aminopyrine (AM) N-demethylase activity about 1.6-fold while not affecting the apparent Km value. In contrast, 4'-CF-induced microsomes decreased the Km of 7-EC O-deethylase activity to about one fourth while significantly increasing the Vmax value. All the activities of AM N-demethylase, 7-EC O-deethylase and 6,7-dimethoxycoumarin O-demethylase in 2'-CF-induced microsomes were inhibited strongly by metyrapone and SKF 525-A, and significantly by diphenhydramine. The three enzyme activities in 4'-CF-induced microsomes were inhibited markedly by alpha-naphthoflavone and significantly by 2-bromo-4'-nitroacetophenone. These results further support the previous proposal that 2'-CF is a PB-type inducer of cytochrome P-450 while 4'-CF is a MC-type inducer.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1993

Cytoprotective action of L-arginine against HCl-induced gastric injury in rats: involvement of nitric oxide?

We examined the cytoprotective effect of L-arginine on gastric damage induced by 0.6 N HCl in rats and investigated whether the mechanism of this action is related to the nitric oxide (NO)-mediated protection. The animals were given 0.6 N HCl by gavage and killed 1 hr later. L-Arginine (100, 300 and 750 mg/kg) given p.o. 30 min before HCl treatment prevented these lesions in a dose-dependent manner, but had no effect when given i.v. (200 mg/kg). Similar effects were observed by D-arginine but not by an equimolar dose of mannitol. This effect of L-arginine (p.o.) was attenuated significantly by prior administration of indomethacin (5 mg/kg, s.c.) but not by NG-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg, i.v.), the NO synthase inhibitor. Both L- and D-arginine produced a reduction in potential difference (PD), inhibition of gastric motility, and increases of luminal pH and mucosal blood flow when they were given intragastrically. Indomethacin significantly mitigated these changes induced by L-arginine except PD reduction, while L-NAME showed significant inhibition only against the increased pH response. We conclude that L-arginine given p.o. exhibits gastric cytoprotection against HCl-induced damage in rats, probably by acting as a mild irritant. The mechanism of this action may appear through "adaptive cytoprotection" mediated by endogenous prostaglandins and does not involve the NO-mediated protective pathway.

Animals↗
PubMed1993

Effect of lactosucrose (4G-beta-D-galactosylsucrose) on fecal flora and fecal putrefactive products of cats.

The effects of lactosucrose (4G-beta-D-galactosylsucrose) on fecal flora and fecal putrefactive products were studied in 3 Himalayan and 5 Persian cats fed 175 mg of lactosucrose/each/day for 2 weeks. During lactosucrose administration, the counts of lactobacilli increased significantly (p < 0.05), whereas the counts of clostridia, including Clostridium perfringens and Enterobacteriaceace decreased significantly (p < 0.05). The levels of fusobacteria and staphylococci were decreased significantly (p < 0.01) on day 7 of lactosucrose administration, while the counts of bacteroides increased significantly (p < 0.05) and day 14 of lactosucrose administration compared to pre-administration. In frequency of occurrence, bifidobacteria increased significantly (p < 0.001) during lactosucrose administration, while Spirochaetaceae and lecithinase-negative clostridia decreased significantly (p < 0.05) on day 14 of lactosucrose administration compared to pre-administration. No detectable change occurred in the counts of other organisms throughout the experimental periods. Fecal concentrations of ammonia, indole, ethylphenol, and urinary ammonia were reduced significantly (p < 0.05) on day 14 of lactosucrose administration. The water content and weight of the feces increased slightly during lactosucrose administration, but the pH values decreased slightly. The environmental ammonia and the fecal odor also decreased remarkably (p < 0.01) during administration.

Animals↗