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Biomedical subjects

K Tsukamoto

Publications and source records attributed to K Tsukamoto.

At least 181 records · Page 10Linked to original sources
PubMed1994

Isolation of two isoforms of the PAX3 gene transcripts and their tissue-specific alternative expression in human adult tissues.

We have isolated two isoforms of cDNA clones from the human PAX3 gene, a candidate gene responsible for Waardenburg syndrome type I (WSI) as well as a gene associated with development of alveolar rhabdomyosarcoma. The gene product is considered to be one of transcription factors, and the two cDNA clones isolated, termed PAX3A and PAX3B, were generated by alternative splicing. The transcripts coded 215 and 206 amino acids, respectively, and shared 196 amino acids at the NH2 end. The amino acid sequence in the common region (residues 1-196) showed a 100% identity with that of exons 1-4 of the mouse Pax-3 gene. However, both of the PAX3 cDNAs lacked the DNA sequence corresponding to the paired-type homeodomain of the mouse Pax-3 gene. Analysis of gene expression in human adult tissues by reverse transcriptase polymerase chain reaction (RT-PCR) revealed tissue-specific expression of this gene. PAX3B was expressed in most of the tissues examined, but the PAX3A type of transcript was detected only in the cerebellum, esophagus, and skeletal muscle.

Adult↗
PubMed1994

Effect of chylomicron remnants on apolipoprotein E synthesis in HepG2 cells.

The effect of chylomicron remnants (CM-R) on apolipoprotein (apo) E synthesis by HepG2 cells was studied. The accumulation rate of apo E in the medium was increased in cells incubated with CM-R (chylo-cells) compared with that in the control cells. However, the abundance of apo E mRNA was not greater in chylo-cells than in control cells. The time course of apo E accumulation in the medium showed that apo E increased in the chylo-cells linearly up to 24 hours, whereas it increased in the control cells linearly only up to 6 hours, when it reached a plateau. The results suggest that the secretion rate of apo E was not affected by incubation with CM-R, but that uptake of the newly secreted apo E by the cells may be depressed by incubation with CM-R. Autoradiography of newly synthesized apo E showed that chylo-cells produced much more "larger" apo E than did the control cells. Two-dimensional electrophoresis of the apo E newly synthesized by the chylo-cells showed that the larger apo E was slightly acidic even after treatment with neuraminidase. Pulse-chase labeling of apo E showed that the larger apo E was secreted by both control and chylo-cells equally and that the larger apo E was converted to regular apo E in the medium more effectively in control cells than in chylo-cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins E↗
PubMed1994

Serum soluble IL-2 receptor (sIL-2R) and eosinophil cationic protein (ECP) levels in atopic dermatitis.

We examined the serum soluble IL-2 receptor and eosinophil cationic protein levels in patients with atopic dermatitis (n = 21), patients with urticaria (n = 12), and normal healthy individuals (n = 14). We found that both soluble IL-2 receptor levels and eosinophil cationic protein levels were significantly higher in atopic dermatitis than in urticaria or normal controls. Although both soluble IL-2 receptor levels and eosinophil cationic protein levels were significantly correlated with clinical severity scores in atopic dermatitis, the correlation between eosinophil cationic protein levels and clinical severity scores was higher than that between soluble IL-2 receptor levels and clinical severity scores. However, soluble IL-2 receptor levels, eosinophil cationic protein levels and clinical severity scores were not significantly correlated with IgE levels. The chronological changes of soluble IL-2 receptor and eosinophil cationic protein levels differ from patient to patient. However, levels of soluble IL-2 receptor and eosinophil cationic protein seem to parallel to each other in 65% of patients with AD. Measurement of serum eosinophil cationic protein or soluble IL-2 receptor levels may be a useful tool to monitor the short-term or long-term disease activity of atopic dermatitis in conjunction with clinical severity scores.

Adolescent↗
PubMed1994

Effect of starving and refeeding on lipid metabolism in suncus.

We have previously reported that fatty liver is easily induced in a novel experimental animal, Suncus murinus (suncus) by withholding food, and that apolipoprotein B (apo B) is not actively synthesized in the liver. In the present paper we describe the effect of starving and refeeding on lipid and lipoprotein metabolism in suncus, in order to explore the mechanisms of induction of fatty liver by starving and of its improvement by refeeding. Starvation induced increase in triglyceride content and decrease in glycogen content of the liver. Although the glycogen content returned to the level before starvation at 12 h after refeeding, the triglyceride content decreased gradually but did not reach the prestarvation level even at 24 h after refeeding in suncus. Plasma lipids, glucose, and insulin levels were decreased by starvation and returned to the levels before starvation between 8 and 24 h after refeeding. On the other hand, the plasma levels of free fatty acid and ketone bodies were elevated significantly by starvation and decreased rapidly by refeeding. These responses to starvation and refeeding, except for the change in hepatic triglyceride, are in common with other experimental animals, suggesting that there are no abnormalities in glucose metabolism or in fatty acid metabolism in suncus. In conclusion, the fatty liver induced by starvation in suncus may be caused by impaired triglyceride transport out of the liver, for which apolipoprotein B is mostly responsible, as reported previously.

Animals↗
PubMed1994

Deficiency of acyl CoA cholesterol acyl transferase activity in suncus liver.

We reported previously that apolipoprotein B is not actively secreted from suncus liver. In the present study we have investigated the hepatic cholesterol metabolism, which plays a critical role in the secretion of apo B. We found that the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase in suncus liver is high and that acyl-coenzyme A: cholesterol acyltransferase (ACAT) activity is almost absent in contrast to rats. As a result, the hepatic content of cholesterol ester, upon which apoprotein B secretion partly depends, is very low in suncus. The deficiency of ACAT activity may cause the defect in active secretion of apoprotein B-containing lipoproteins in suncus.

Animals↗
PubMed1994

DHICA oxidase activity of TRP1 and interactions with other melanogenic enzymes.

Tyrosinase-related protein 1 (TRP1) maps to the brown locus in mice. Although the specific function of TRP1 has been in dispute, mutations in its structural gene result in the formation of brown rather than black melanin. We have investigated the melanogenic function of TRP1 by using immune-affinity purification of the protein and also by using transfection of its gene into fibroblasts to study its characteristics. We show that TRP1 has the ability to oxidize DHICA, a melanogenic intermediate derived from DOPAchrome. In addition, TRP1 has the ability to interact with tyrosinase and significantly stabilize the latter's catalytic function.

Animals↗
PubMed1994

Interaction of oxyimino beta-lactams with a class C beta-lactamase and a mutant with a spectrum extended to beta-lactams.

The class C beta-lactamase of Citrobacter freundii GN346 is a typical cephalosporinase comprising 361 amino acids, and substitution of the glutamic acid at position 219 in the enzyme by lysine was previously shown to broaden its substrate spectrum to oxyimino beta-lactams (K. Tsukamoto, R. Ohno, and T. Sawai, J. Bacteriol. 172:4348-4351, 1990). To clarify this spectrum extension from the kinetic point of view, the interactions of cefuroxime, ceftazidime, and aztreonam with the wild-type and mutant enzymes were analyzed. In addition to aztreonam, known as a progressive inhibitor of class C beta-lactamases, cefuroxime and ceftazidime were found to act as progressive inhibitors of the wild-type enzyme. On the other hand, only aztreonam showed weak progressive inhibition of the mutant enzyme. On the basis of kinetic parameters, a minimum scheme for interaction of the oxyimino beta-lactams with the wild-type enzyme was proposed, and the rate-limiting step of the hydrolysis of unfavorable substrates was indicated to be conversion of the stable acyl-enzyme intermediate to the unstable intermediate. In aztreonam hydrolysis by the mutant enzyme, the reaction rate at the rate-limiting step was 2,000 times that of the wild-type enzyme. These results indicate that the mutation at position 219 disturbs the stabilization of the stable intermediate.

Anti-Bacterial Agents↗
PubMed1994

[Effects of voluntary wheel running on health indexes in rats with SRBC-induced inflammation].

The effects of voluntary running exercise on health indexes in rats were studied before and after Sheep Red Blood Cell (SRBC)-induced inflammation. Male Fischer rats (SPF) 8 weeks of age were housed in individual sedentary cages (sedentary group) or in individual wheel-running cages (exercise group) for 4 months. Then all rats were injected with 20% SRBC (0.5 ml/100g body weight) i.p. Voluntary running activity averaged 1408m/day, reached a peak (2913m/day) at the 25th day and waned over time, reaching a plateau at the 60th day (about 1000m/day). In spite of a significant increase in food intake (117%), exercising rats gained significantly less weight (93%) than sedentary rats at all times in experimental period. The exercise group also showed a significant decrease in the value of serum triglyceride (TG) and total cholesterol (T. CHO) (TG p < 0.0002, T. CHO p < 0.03). The hematocrit (Ht) and hemoglobin concentration (Hb) were higher in the exercised rats, and at 4 days after i.p. SRBC, the difference became statistically significant (Ht p < 0.0002, Hb p < 0.003). Thus, protective effects against the decrease of Ht and Hb were demonstrated in the exercised group. Perhaps this inflammation did not impair liver function severely; sedentary rats had normal or slightly higher levels of GOT and GPT. On the other hand, exercised rats had lower GOT and GPT. Significant differences were found between the groups (GOT, GPT p < 0.0001).

Animals↗
PubMed1994

[Effects of crowding on immune functions in mice].

The effects of several types of crowding on immune functions were studied in mice. This study consisted of two experiments. Experiment one: Male BALB/c mice were initially housed in groups of four mice per cage. After fourteen days of acclimation, the mice were randomly divided into three groups, Control (four mice per cage, control group), Crowd-I (four mice per small space) and Crowd-II (sixteen mice per cage). These conditions were maintained for seven days. The results of experiment one were as follows: (1) The percentage of lymphocytes in the blood of Crowd-II was significantly lower than that of Control (p < 0.05). (2) The percentage of neutrophils and the absolute number of neutrophils in blood of Crowd-II were significantly higher than in Control (p < 0.05). (3) Superoxide production activity (NBT reduction activity) of blood neutrophils in Crowd-II tended to be depressed, and phagocytic activity of neutrophils was significantly depressed in Crowd-II as compared with Control (p < 0.01). These results suggest that the complexity of interrelationships among mice caused by an increase in the number of animals per cage is a very important stress factor. Experiment two: Male BALB/c mice were initially housed in groups of five mice per cage. After fourteen days of acclimation, the mice were divided into three groups, Control (five mice per cage, control group), Crowd-(1) (five mice per cmall space) and Crowd-(2) (twenty mice per cage). In Control and Crowd-(1), the same mice were used as in the acclimation period. These conditions were maintained for seven days. In this period, on the second day, all the mice were injected intraperitoneally with sheep red blood cells (SRBC). The results of experiment two were as follows: (1) The specific humoral immune response to SRBC was investigated in terms of the number of PFC in the spleens and hemagglutination in sera, but significant differences were not found among the groups. (2) Plasma IgG levels in the Crowd-(1) were significantly higher than those in Control (p < 0.05). (3) Both superoxide production activity and phagocytic activity of neutrophils were significantly depressed in Crowd-(2) as compared with Control (p < 0.01, respectively), whereas each neutrophil function of Crowd-(1) tended to be enhanced as compared with Control.

Animals↗
PubMed1994

Subarachnoidal abscess associated with bacterial meningitis in infants--two case reports.

Two infants, an 11-month-old boy and a 7-month-old girl, presented with subarachnoidal abscess associated with severe bacterial meningitis refractory to intensive managements with antibiotics. Computed tomography (CT) revealed bifrontal extracerebral low-density areas and remarkably enhanced surfaces of the bilateral frontal lobes postcontrast. Surgical exploration disclosed thick pus accumulation in the subarachnoid space which required curettage. The boy developed appropriately for his age, but the girl showed severe psychomotor retardation because of additional complications such as subdural fluid collection and hydrocephalus associated with the subarachnoidal abscess. Appropriate early neurosurgical management of subarachnoidal abscess is essential for satisfactory psychomotor development. Postcontrast CT should be performed to detect the subarachnoidal abscess as early as possible, and extensive craniotomy to remove the subarachnoidal pus accumulation performed to preserve psychomotor development.

Brain Abscess↗
PubMed1994

MR imaging of the uterus: findings from high-resolution multisection dynamic imaging with a surface coil.

MR imaging of the female pelvis with a local coil (multiple phased array coils) has been reported. With this method, the signal-to-noise ratio (S/N) is improved so that high-resolution images can be obtained. Dynamic contrast-enhanced MR imaging has been reported to be useful in diagnosing uterine neoplasms. However, dynamic MR imaging is done in only limited imaging planes. When multisection dynamic MR imaging with fast gradient-echo sequences is combined with the use of a local coil, high-resolution images can be obtained throughout the entire uterus during a single breath-hold. This pictorial essay illustrates the appearance of the normal uterus and malignant uterine neoplasms on high-resolution multisection dynamic MR images obtained with a Helmholtz-type surface coil.

Adult↗
PubMed1994

The tyrosinase gene family--interactions of melanogenic proteins to regulate melanogenesis.

Several genes critical to the regulation of melanin production in mammals have recently been cloned and characterized. They map to the albino, brown, and slaty loci in mice, and encode proteins with similar structures and features, but with distinct catalytic capacities. The albino locus encodes tyrosinase, an enzyme with three distinct melanogenic functions, the brown locus encodes TRP1 (tyrosinase-related protein-1), and the slaty locus encodes TRP2, another tyrosinase related-protein. TRP2 functions as DOPAchrome tautomerase, an enzyme that preserves the carboxylic acid content of melanins, which would be spontaneously lost in its absence, while TRP1 is able to oxidize the DHICA produced by TRP2. In this study we have used three different systems (immune-affinity purified melanogenic enzymes, mutant melanocytes, and transfected cells) to examine the enzymatic interactions of these proteins, and their stabilization in a complex which significantly increases their physiological half-life. When extrapolated to the melanocyte, our results demonstrate the catalytic functions of these proteins and suggest how they might stably interact within a melanogenic complex in the melanosome to regulate the quantity and quality of melanin synthesized.

3T3 Cells↗
PubMed1994

[Effect of calcium antagonist (benidipine) and alpha 1 blocker (urapidil) on renal hemodynamic responses to two acute environmental stresses in spontaneously hypertensive rats (SHR)].

Renal hemodynamic responses were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto Rats (WKY) to two acute stresses: environmental stress (foot shock (FS) and air jet (AS)). The effects of calcium channel blocker (benidipine) and alpha 1 blocker (urapidil) on these responses were studied using an ultrasonic pulsed Doppler flowmeter. The increments in mean arterial pressure (MAP) and renal vascular resistance (RVR) were greater in SHR during both stresses. On the other hand, the decrease in the renal blood flow (RBF) with these stresses almost disappeared with renal denervation. These renal hemodynamic responses in SHR disappeared with alpha 1 blocker (urapidil), but not with calcium channel blocker (benidipine). The sympathetic nervous system became hyperactive in SHR under environmental stress, Which induced specific renal hemodynamic change. These results suggest that investigations on essential hypertension should focus on clarifying not only systemic hypertensive reaction, but also changes in renal hemodynamics. Furthermore, it is necessary for antihypertensive therapy to take these hemodynamic changes into consideration.

Acute Disease↗
PubMed1994

[Management of the uterine endometrial cancer cases whose cytological and histologic specimens cannot be obtained from the uterine cavity--assessment by CA125 or vaginal ultrasonography].

An examination for endometrial cancer has been done by cytology. However, cytology is sometimes not possible because of closed or narrow cervix of postmenopausal woman. We did a retrospective study regarding the usefulness of CA125 or transvaginal ultrasonography in postmenopausal cases. The mean +/- S.D. of CA125 in normal menopausal women was 10.3 +/- 3.0 U/ml. The value of mean +/- 2S.D., the finding of Relative Operating Characteristic curve and the purpose that false positive was 0%, so we set 17 U/ml as the cut off value for CA125. In 46 cases with postmenopausal endometrial carcinoma, 23 cases were screened; and in 30 cases with surgical stage I, 10 cases were screened with this cut off value. The echoic patterns for uterine cavities which were observed by transvaginal ultrasonography were divided into 4 patterns (type I: anechoic pattern, type II: linear pattern, type III: clear mass pattern, type IV: unclear mass pattern). In 20 cases with postmenopausal endometrial cancer, 19 cases had type III or IV. In 41 normal postmenopausal women, 26 cases showed an anechoic pattern and 14 cases showed a linear pattern. It was found that 97.5% of cases with anechoic or linear patterns were normal endometrium. The screening by transvaginal ultrasonography was more useful than CA125. However CA125 was more useful than transvaginal ultrasonography in detecting lymph node metastasis.

Aged↗
PubMed1994

[Experimental and clinical evaluation of 99mTc-HMPAO as a sensitive marker for chemical lung injury].

To investigate whether 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) can be a sensitive marker of lung injury, an animal model of lung injury was designed in the rabbits using the injection of a low dose (0.05 ml/kg) of oleic acid. In the injured rabbit lungs, electron microscope revealed morphologic changes localized in the microvascular endothelium (edematous change), although their chest radiographies and light microscope did not show any significant changes compared to the controls. In these situations, 99mTc-HMPAO showed a diffusely, high pulmonary uptake, which occurred rapidly within the first 1 min after the injection. Clinically, the lungs in the patients who had been administered with cytotoxic anti-cancer drugs showed a significantly higher 99mTc-HMPAO uptake compared to the controls. These findings indicate that 99mTc-HMPAO may have potential as a sensitive marker of chemical lung injury.

Adult↗
PubMed1994

[Carbohydrate and lipid metabolism in liver cirrhosis].

The liver is of prime importance in carbohydrate and lipid metabolism. Thirty to 60% of the ingested carbohydrates are taken up by the liver, and stored as glycogen. In the fasted state, the liver releases glucose by glycogenolysis and gluconeogenesis. The liver, therefore, acts as a "buffering organ' in carbohydrate metabolism to keep the blood glucose level in a physiological state. In liver cirrhosis, abnormality in carbohydrate metabolism is commonly observed, characterized by hyperinsulinemia and insulin resistance. The liver produces cholesterol, triglyceride, and phospholipid, secretes and uptakes lipoproteins, and discharges cholesterol in the form of bile. In addition, the liver produces important enzymes for lipoprotein metabolism. In consequence, many typical,. features are observed in lipid metabolism in hepatic diseases.

Carbohydrate Metabolism↗