Biomedical subjects

M Kuroda

Publications and source records attributed to M Kuroda.

At least 307 records · Page 17Linked to original sources

PubMed1993

Synaptic organization and prefrontal corticothalamic termination in the mediodorsal thalamic nucleus of the cat.

The synaptic organization of the mediodorsal thalamic nucleus (MD) in the cat have been studied with the electron microscope, and correlated with the termination of the medial prefrontal corticothalamic afferents using the method of anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). The neuropil of MD was divided into glomerular and extraglomerular regions. A synaptic glomerulus was composed of a central dendrite and some different presynaptic profiles with astroglial ensheathment. The prevalent presynaptic elements in glomeruli were presynaptic dendrites (PSDs) that contained pleomorphic vesicles, and formed symmetric synaptic contacts and puncta adhaerentia junctions with central dendrites. One or two large terminals with round vesicles and asymmetric specializations (LR) also participated in glomerular formations. They were invariably presynaptic to central dendrites and PSDs. As terminals less frequently found within glomeruli, there were small-sized terminals with round vesicles and asymmetric synaptic junctions with PSDs. In the extraglomerular neurophils, small to medium-sized terminals with pleomorphic vesicles (SMP) were found besides the presynaptic profiles identified in glomerular regions. These SMP terminals formed axodendritic and axosomatic symmetric synapses. WGA-HRP injections into the medial prefrontal cortex resulted in anterograde labelings in not only SR but also LR presynaptic terminals. SR boutons made up the majority of labeled terminals, and they were found only in the extraglomerular neuropil. While labeled LR terminals were detected in the extraglomerular neuropil and synaptic glomeruli with less encounter. The results of the present study show that the synaptic organization in MD of the cat is similar to that in other thalamic relay nuclei and in MD of the monkey. Further, MD receiving two subsets of synaptic terminations from the prefrontal cortex might play a different functional role in regulating the neural circuit between MD and the prefrontal cortex in comparison with that in the sensory and motor thalamic nuclei that receive only SR terminals from the sensorimotor cortex.

Animals↗

PubMed1993

[Tuberculosis of the female urethra: a case report].

A 52-year-old female with the chief complaint of miction pain was referred for the examination of a urethral nodule. Physical inspection revealed the meatus to be reddish and swollen. The painless nodule (1 x 1 x 2 cm) was situated between the urethra and vagina on transvaginal examination. Chest X-ray, drip infusion pyelography (DIP) and urethrocystography (UCG) showed no evidence of tuberculosis. Bladder mucosa was normal on cystoscopy. Mycobacterium tuberculosis was not detected from urine or sputum. The nodule was resected along with a portion of the urethra. Histopathological examination revealed tuberculous granuloma of the urethra.

Drug Therapy, Combination↗

PubMed1993

[Echocardiographic study in adult patients with Down's syndrome].

In Down's syndrome (DS) mental retardation accompanying chromosomal abnormalities is seen, and the incidence of associated congenital heart abnormalities is also known to recent years, the accelerated aging and premature senility associated with DS have attracted attention. In the present study, we examined cardiac lesions using echocardiography in a group of asymptomatic adult DS subjects discussed the relation between these lesions and premature aging. The subjects comprised 28 adult DS patients ranging in age from 20 to 46 years (mean +/- SD, 30.8 +/- 8.9 years) residing in 8 institutions in Fukui prefecture. The presence of DS was confirmed in all cases by chromosomal examination, which revealed 21-trisomy in 25 and mosaic type in three. Of indices of left heart function, the end diastolic volume index (EDVI) and end systolic volume index (ESVI) showed significantly reduced values, whereas indices of systolic function such as the ejection fraction (EF) and mean velocity of circumferential fiber shortening (mean Vcf) showed significantly elevated values. The results of early diastolic left ventricular function, which has been noted to be related to aging, did not show any significant difference as determined by observation of mitral valve dynamics. On the other hand, morphologically, mitral valve prolapse (MVP) was found significantly more frequently in the DS group (17.9%) as compared to a normal control group. Also, valvular calcification (14.3%) and aortic valve regurgitation (AR, 11%) were both frequently noted. Whether signs such as valvular calcification are findings related to accelerated aging will require further study.

Adult↗

PubMed1992

Neuronal and synaptic composition of the mediodorsal thalamic nucleus in the rat: a light and electron microscopic Golgi study.

The distribution and dendritic domain of neurons in each segment of the mediodorsal thalamic nucleus (MD) have been studied in the rat with the Golgi technique. In addition, a combined Golgi method-electron microscopic (Golgi-EM) study was undertaken to determine the distribution of morphologically distinct synapse types along the dendrites of individual identified neurons in MD. All the subdivisions or "segments" of MD (medial, central, lateral) contained both stellate and fusiform cells. The dendritic domain of both types of cells was predominantly restricted to the same segment of MD that contained the cell body of the neuron. Typical stellate neurons were found near the center of each segment, with radiating dendrites that extended to but not across the boundaries of the segment. Fusiform cells were usually located close to the segmental or nuclear boundaries and tended to have dendrites oriented parallel to those borders; again, the dendrites tended not to extend across borders between segments or at the outer edge of MD. In the medial segment of MD many fusiform cells had especially bipolar dendritic configurations, generally with a dorsoventral orientation. Because no small neurons were identified that might correspond to thalamic interneurons, all the impregnated cells in MD are presumed to be thalamocortical projection neurons. These results indicate that cells and their major dendrites are confined to a single segment of MD, with little dendritic overlap across segmental or nuclear borders. The segments of MD may therefore be considered to be relatively independent subnuclei. The distribution of the four types of synapses previously identified in MD (Kuroda and Price, J. Comp. Neurol., 303:513-533, 1991) was determined along several identified dendrites studied with the Golgi-EM method. Primary dendrites were contacted mostly by large axon terminals, including both large, round vesicle (LR) terminals and large, pleomorphic vesicle (LP) terminals, as well as a few small to medium sized terminals with pleomorphic vesicles (SMP). No small terminals with round vesicles (SR terminals) were observed to make synapses with primary dendrites. Secondary and tertiary dendrites received synapses from all types of axon terminals. Higher order dendrites were contracted predominantly by SR boutons, but they also carried some LR and SMP terminals. In addition, SMP boutons were often found to form symmetric contacts with cell somata.

Animals↗

PubMed1992

Distribution of the piriform cortical terminals to cells in the central segment of the mediodorsal thalamic nucleus of the rat.

A Golgi electron microscopic study was undertaken to investigate the distribution of terminals from the piriform cortex that synapse on identified dendrites of neurons in the central segment of the mediodorsal thalamic nucleus of the rat. The piriform cortical terminals were identified as degenerating terminals following lesions in the cortex. They consisted of two types, i.e., large (LR type) and small (SR type) presynaptic terminals, both of which had round synaptic vesicles and formed asymmetric synaptic contacts. SR boutons terminated preferentially onto distal dendrites and never synapsed on primary dendrites. LR terminals synapsed preferentially on proximal dendrites, but were also found on more distal dendritic segments.

Animals↗

PubMed1992

Corn kernel cysteine proteinase inhibitor as a novel cystatin superfamily member of plant origin. Molecular cloning and expression studies.

A full-length cDNA clone for a cysteine proteinase inhibitor (cystatin) was isolated from a lambda gt10 cDNA library of immature corn kernels by screening with a mixture of cDNA inserts for oryzacystatins I and II. The cDNA clone spans 960 base pairs, encoding a 135-amino-acid protein containing a signal peptide fragment. The protein, named corn cystatin I, is considered to be a member of the cystatin superfamily, since it contains the commonly conserved Gln-Val-Val-Ala-Gly region that exists in most known cystatins as a probable binding site and is significantly similar to other cystatins in its overall amino acid sequence. Corn cystatin I expressed in Escherichia coli showed a strong papain-inhibitory activity. Northern blot analysis showed that the amount of mRNA for corn cystatin I reaches a maximum 2 weeks after flowering and then decreases gradually.

Amino Acid Sequence↗

PubMed1992

Resistance of the melibiose carrier to inhibition by the phosphotransferase system due to substitutions of amino acid residues in the carrier of Salmonella typhimurium.

The melibiose carrier of Salmonella typhimurium is under the control of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). We isolated mutants of the melibiose carrier that showed resistance to inhibition via the PTS. Growth of the mutants on melibiose was not inhibited by 2-deoxyglucose, a non-metabolizable substrate of the PTS, although growth of the parent strain was inhibited. Transport activity of the melibiose carrier in the mutants was fairly resistant to inhibition by 2-deoxyglucose, although the activity in the parent was sensitive to inhibition. We cloned the mutated melB gene that encodes the melibiose carrier, determined the nucleotide sequences, and identified replaced nucleotides. The mutations resulted in substitutions of Asp-438 with Tyr, Arg-441 with Ser, or Ile-445 with Asn. All of these residues are in the COOH-terminal region of the carrier. The secondary structure of this region is predicted to be an alpha-helix, and the mutated residues were on the same side of the helix. This region showed sequence similarity to a region of the MalK protein, in which substitution of amino acid residues also resulted in PTS-resistant mutants. Thus the COOH-terminal portion of the melibiose carrier is important for the interaction of dephosphorylated IIIGlc, which is an entity causing reversible inactivation of the carrier.

Amino Acid Sequence↗

PubMed1992

Histamine N-methyltransferase from rat kidney. Cloning, nucleotide sequence, and expression in Escherichia coli cells.

Complementary DNA clones encoding rat kidney histamine N-methyltransferase have been isolated using synthetic oligonucleotide probes based on partial amino acid sequences of tryptic peptides of the purified enzyme. The 1.3-kilobase cDNA consisted of a 5'-noncoding region of 8 nucleotides, a coding region of 885 nucleotides, and a 3'-noncoding region of 369 nucleotides. The encoded protein of 295 amino acid residues had a calculated molecular weight of 33,940.2. After introduction of a prokaryotic expression vector containing the isolated cDNA, Escherichia coli cells expressed histamine N-methyltransferase activity. The enzyme expressed in these cells was isolated and purified as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whose mobility was identical to the natural enzyme purified from rat kidney. The recombinant enzyme had Vmax and Km values for both histamine and S-adenosylmethionine identical to those of the natural enzyme. All of the inhibitors of the natural enzyme tested showed similar Ki values on both recombinant and natural enzyme.

Amino Acid Sequence↗

PubMed1992

Cloning and sequencing of the melB gene encoding the melibiose permease of Salmonella typhimurium LT2.

The nucleotide sequence of the melB gene coding for the Na+ (Li+)/melibiose symporter of Salmonella typhimurium LT2 was determined, and its amino acid sequence was deduced. It consists of 1428 bp, corresponding to a protein of 476 amino acid residues (calculated molecular weight 52,800). The amino acid sequence is homologous to that of the melibiose permease of Escherichia coli K12, with 85% identical residues. All, except one, of the amino acid residues that have been reported to be important for cation or substrate recognition in the melibiose permease of E. coli are conserved in the melibiose permease of S. typhimurium. In addition, part of the sequence resembles the lactose permease of Streptococcus thermophilus, the animal glucose transporter (GLUT1), the plasmid-coded raffinose permease (RafB), and the NADH-ubiquinone oxidoreductase chain 4 (Nuo4) of Aspergillus amstelodami.

Amino Acid Sequence↗

PubMed1992

Immunohistochemical study on the distribution of sarcoplasmic reticulum calcium ATPase in various human tissues using novel monoclonal antibodies.

Novel monoclonal antibodies were raised against sarcoplasmic reticulum calcium (Ca2+)-ATPase of human skeletal muscle. Immunohistochemical analysis demonstrated that these antibodies, designated 6F5 and 7F10, bind Ca(2+)-ATPase of non-muscle tissue of the adult including parathyroid, islets of Langerhans, anterior lobe of the pituitary gland and photoreceptor cells of the retina as well as skeletal muscle. A positive reaction was also found for fetal tissues including skeletal muscle, heart, chondrocytes and peripheral nerves. Our results for distribution suggest that Ca(2+)-ATPase is strongly expressed in the tissues and cells in which signal transduction is actively carried out by Ca2+ release from the cytoplasmic Ca2+ pool.

Antibodies, Monoclonal↗

PubMed1992

Urinary fibrin and fibrinogen degradation products and the origin of hematuria.

We examined urinary fibrin and fibrinogen degradation product (U-FDP) concentrations in pediatric patients with hematuria using the rapid and highly-sensitive latex particle agglutination test (LPAT), and assessed the value of this test for the localization of the site of hematuria. Patients with hematuria were divided into two groups: 60 with glomerular hematuria and 46 with non-glomerular hematuria. If U-FDP concentrations less than 0.25 microgram/ml are accepted as an indicator of glomerular bleeding, the sensitivity and specificity of localization of glomerular hematuria in the present study were 78% (47/60) and 89% (41/46), respectively. The high U-FDP concentrations observed in patients with non-glomerular hematuria may reflect direct bleeding into the urinary tract. Since all 13 patients with glomerular hematuria and U-FDP concentrations of 0.25 microgram/ml or more had coexistent erythrocyte cylindruria, the U-FDP test seems to be compensated with combined urinalysis for the relatively lower sensitivity. We conclude that a knowledge of U-FDP concentrations by LPAT can be of help in localizing the site of bleeding in hematuria.

Adolescent↗

PubMed1992

Mutual recognition between polymerized liposomes. IV. Polysaccharide-lectin system.

As a model of cell-cell recognition processes, the association processes of a polysaccharide (mannan)-carrying liposome with a lectin (Concanavalin A, Con A)-carrying polymerized liposome were followed by turbidimetry. The association process was strongly inhibited by the addition of a low molecular weight sugar, methyl-alpha-D-mannopyranoside, which shows that the association between the liposomes is due to the specific interaction between Con A and mannan. The association rate constant obtained was much smaller than the theoretical value for a diffusion-controlled binary association process. This implies that the association rate of liposomes is limited by the recognition between complementary ligands bound on the liposome surfaces. Another reason for the smaller association rate constant in the liposome-liposome system is the repulsive hydration effect. The effect of the surface density of the lectin immobilized on the liposome on the recognition was also examined.

Concanavalin A↗

PubMed1992

Preferential utilization of glucose over melibiose, and vice versa, in a pts mutant of Salmonella typhimurium.

Preferential utilization of glucose and melibiose was investigated in wild type cells and in pts mutant (ptsI-leaky) cells of Salmonella typhimurium. A typical diauxic growth and preferential utilization of glucose over melibiose were observed in wild type cells when these two sugars were added as carbon source. Similar results were obtained with a pts mutant (SB1476) although utilization of glucose was slow. When cyclic adenosine 3',5'-monophosphate (cAMP) was added to the culture medium to release the catabolite repression, preferential utilization of glucose was still observed in wild type cells. With glucose-induced mutant cells, preferential utilization of glucose was observed in the presence of cAMP. Gradual utilization of melibiose took place when glucose concentration in the medium decreased. Surprisingly, preferential utilization of melibiose over glucose was observed with melibiose-induced and glucose-uninduced mutant cells in the presence of cAMP.

Cell Division↗

PubMed1992

Effects of pravastatin sodium alone and in combination with cholestyramine on hepatic, intestinal and adrenal low density lipoprotein receptors in homozygous Watanabe heritable hyperlipidemic rabbits.

Pravastatin sodium (pravastatin), a tissue-selective inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, was administered alone (50 mg/kg) or in combination with cholestyramine, a bile acid sequestrant resin, at the level of 2% in the diet to homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits for 4 weeks. The low density lipoprotein (LDL)-cholesterol levels were reduced by 29% and 56% with pravastatin alone and the combination treatment, respectively. Hepatic LDL receptor activity was increased by 11.2- and 13.9-fold with pravastatin alone and the combination treatment, respectively. The LDL receptor activity in the untreated homozygous WHHL rabbits was only 2.5% of that in the normal rabbits. mRNA for the LDL receptor in the liver was also increased by 2.1- and 3.4-fold with pravastatin alone and the combination treatment, respectively. On the other hand, mRNA for the LDL receptor in the adrenal gland was not affected by pravastatin and the combination treatment, whereas the mRNA in the intestine was increased in both groups. These results suggest the following: 1) the induction of hepatic LDL receptor activity by the treatment of pravastatin alone or in combination with cholestyramine is the main cause of the reduction of serum cholesterol levels by these treatments even in LDL receptor-deficient animals. 2) The induction of the mRNA for the LDL receptor in the liver and intestine, but not that in the adrenal gland, might be a reflection of the tissue-selective inhibition of cholesterol synthesis by pravastatin.

Adrenal Glands↗

PubMed1992

Report of a study using phantom materials, and clinical experience with simultaneous radio-hyperthermotherapy.

Simultaneous radiohyperthermotherapy (SRH) is a combined hyperthermia-radiation therapy in which irradiation is given during heating. Mutual interference between the high energy radiotherapy system (Toshiba LMR-15A) and the 13.56 MHz capacitive heating system (Omron HEH-500C) was tested with phantom materials prior to a clinical trial with SRH. The energy and flatness of irradiation were not affected by the heating system within the range of clinical use. The high energy radiotherapy system did not affect the increase or distribution of temperature during simultaneous treatment. The results of this phantom study indicated that these apparatuses would not produce clinically significant mutual interference during SRH. A clinical trial was performed on a 57-year-old woman with postoperative recurrence of rectal cancer. This is the first reported clinical case treated with true SRH in which external irradiation was administered during mid capacitive heating. Twelve SRH treatments were performed on the recurrent lesion at a frequency of twice a week for six weeks using the apparatuses described above. There was a significant reduction in pain after treatment. The tumor marker carcinoembryonic antigen (CEA) level decreased after treatment. On CT images taken after treatment, the tumor site became a low density area which indicated necrosis. There were no side effects. These results suggest that further clinical study of SRH should be performed to clarify its advantages.

Body Temperature Regulation↗

PubMed1992

Cepharanthin reduces thermotolerance by enhancing thermosensitivity in NIH3T3 cells.

The effects of cepharanthin (Ce), glycyrrhizin (G), verapamil (V), and G plus V on induced thermotolerance in NIH3T3 cells were studied. Cells were heated with or without the drug at 45 degrees C for 20 min (the first heating), incubated at 37 degrees C for 12h (the incubation period), and heated again at 45 degrees C for 0-210 min (the second heating). G and V were added throughout the experiment, while Ce was added throughout the experiment or during only the first or second heating, or the incubation period. The cells were harvested after the second heating to evaluate cell survival. In control experiments without any drug, thermotolerance developed and reached the highest peak in the cells incubated for 12h at 37 degrees C. However, thermotolerance in the control cells was suppressed by incubating them at 0 degree C, but developed by subsequent incubation at 37 degrees C. This suggests that the acquisition of thermotolerance by the cells required metabolic processes during the incubation at 37 degrees C. When each drug was present throughout the experiment, only Ce or the combined use of G and V was effective in reducing thermotolerance. Thermotolerance was also suppressed in the presence of Ce during the second heating. These results indicate that Ce reduces thermotolerance by enhancing thermosensitivity rather than by inhibiting the development of thermotolerance.

3T3 Cells↗

PubMed1992

[Guanidino compounds in the elderly].

To examine the metabolism of guanidino compounds in the elderly, we measured the serum concentrations of urea nitrogen, creatinine (Cr), guanidinoacetic acid (GAA) and creatine (CR) in middle-aged and elderly subjects. We also measured muscle mass in the elderly. The elderly subjects tended to have lower serum GAA concentrations than middle-aged subjects. On the contrary, CR concentrations of elderly subjects were higher than those of middle-aged subjects. Bedridden elderly subjects tended to have lower serum GAA concentrations and lighter muscle mass than ambulatory elderly subjects. On the contrary, serum CR concentrations of bedridden subjects were higher than those of ambulatory subjects. CR is an essential substance for muscle energy metabolism. These results indicate that high serum CR concentrations due to low CR metabolism in skeletal muscle might suppress glycine amidinotransferase (GAT) activity, resulting in decreased GAA production in the elderly.

Aged↗

PubMed1992

[Surveillance after orchiectomy for stage I testicular seminoma].

The results of treatment by orchiectomy and radiotherapy for stage I testicular seminoma are excellent with cure rates exceeding 95% and relapse rates less than 5%. However, after the development of successful surveillance programs for stage I nonseminomatous testicular cancers, the role of radiotherapy has been questioned by some authors and they proposed a "surveillance policy" for these patients. The purpose of this study was to determine the percentage of patients cured by orchiectomy alone, percentage who ultimately required therapy for occult metastases, site of recurrence, and over-all cure rate and treatment morbidity. And these data were compared with those of adjuvant radiotherapy group retrospectively. Twenty seven patients were treated with adjuvant radiotherapy (RT group). Since 1986, 23 patients with stage I testicular seminoma entered the "surveillance only" protocol at our institution (S group) with a follow-up between 14 and 70 months (median 43 months). Informed consent for the policy of surveillance was obtained. Follow up consisted of physical examination, determination of serum tumor markers and chest X-ray bimonthly for 2 years, every 3 months for 1 year, every 6 months for 2 years and annually thereafter to 10 years. CT scans were performed every 4 months for 3 years, every 6 months for 2 years. Two patients in S group (8.7%) relapsed at 4 and 7 months after orchiectomy with nonbulky retroperitoneal disease (less than 5 cm in diameter), whereas only 1 (3.7%) irradiated patients did so after 4 months.

Adult↗