Biomedical subjects

Masafumi Wasa

Publications and source records attributed to Masafumi Wasa.

14 recordsLinked to original sources

PubMed2005

Glutamine regulates amino acid transport and glutathione levels in a human neuroblastoma cell line.

Both amino acid transport and glutathione play a key role in regulating cancer cell growth. Glutamine can serve as an important ATP source for cancer cells, and it can supply glutamate, a precursor for the synthesis of glutathione, by the hydrolysis of glutamine. We examined the effects of glutamine concentrations [2 mM (control), 400 microM, 200 microM, and 0 microM] on cell growth, amino acid transport, and glutathione levels in a human neuroblastoma cell line, SK-N-SH, by using cell culture technique. Cell growth rates were dependent on glutamine concentrations in culture media. Glutamate transport significantly increased in glutamine-deprived groups, and this increase was remarkable in lower glutamine groups (200 microM and 0 microM glutamine). Glutamine deprivation resulted in a significant decrease in glutathione levels by 20% compared with control, but glutathione in 0 microM glutamine was maintained with the same levels found in 400 microM and 200 microM glutamine. DNA and protein synthesis correlated directly with glutamine concentrations in culture media. Our results suggest that glutamine mediates neuroblastoma cell proliferation by regulating amino acid transport and glutathione synthesis, both when sufficient nutrients are present and when key nutrients such as glutamine are in limited supply.

Amino Acids↗

PubMed2005

Glutamine stimulates amino acid transport during ischemia-reperfusion in human intestinal epithelial cells.

BACKGROUND: The potential mechanism of intestinal ischemia-reperfusion (I/R) injury includes oxygen-derived toxic free radicals. We tested the hypothesis that glutamine increases intracellular glutathione, a protective substrate against oxidative stress, by stimulating membrane amino acid transport during I/R using human intestinal epithelial cell line Caco-2. METHODS: Ischemic conditions were obtained by combining both hypoxic (1%O2-5%CO2-94% N2) and nutrient-deprived (Phosphate-Buffered Saline; PBS) conditions. After 2 h of ischemia, re-oxygenation (5%CO2-95% air) was initiated and the culture medium was changed to PBS, PBS supplemented with amino acids (A.A.), and PBS supplemented with 2 mm glutamine plus amino acids (Gln) (reperfusion). After 4 h of reperfusion, the transport of 3H-glutamine, 3H-glutamate, and 3H-leucine was assayed and intracellular glutathione was measured. 3H-thymidine incorporation was measured for the determination of DNA synthesis. Data (mean +/- SD) were analyzed by ANOVA. RESULTS: Ischemia decreased Na+-dependent glutamine, Na+-dependent glutamate, and Na+-independent leucine transport compared with control (P < 0.01). After reperfusion, glutamine and glutamate transport in the PBS and A.A. groups decreased significantly compared with control (P < 0.01), whereas glutamine supplementation increased glutamine transport to the levels in control (P < 0.01) and partially increased glutamate transport (P < 0.01). Leucine transport significantly increased in the A.A. and Gln groups compared with the PBS group. Glutamine significantly increased intracellular glutathione and DNA synthesis compared with the PBS and A.A. groups (P < 0.01). CONCLUSIONS: This study demonstrated that glutamine up-regulates amino acid transport during I/R in human intestinal epithelial cells, possibly resulting in increased intracellular glutathione and DNA synthesis.

Amino Acids↗

PubMed2004

Amino acid transport is down-regulated in ischemic human intestinal epithelial cells.

Amino acid transport across the plasma membrane is essential for supplying enterocytes with amino acids for cellular metabolism. We studied amino acid transport during ischemic conditions using human intestinal epithelial cell line Caco-2. Cells were incubated under nutrient-deprived (phosphate-buffered saline, PBS), hypoxic, and ischemic (PBS+hypoxia) conditions. Ischemia resulted in a significant decrease in glutamine transport by a mechanism that decreased V(max) without affecting K(m). The expression of system ATB degrees (glutamine transporter) mRNA decreased in the ischemic and nutrient-deprived groups, suggesting that the down-regulation of glutamine transport is due to modification of expression of the ATB degrees gene. The transport of glutamate and leucine, DNA synthesis, and intracellular glutathione also decreased in the ischemic group. These findings throw some light on the mechanism of intestinal epithelial damage during ischemia.

Amino Acid Transport System ASC↗

PubMed2004

Laparoscopic left-sided Nissen fundoplication in children.

It is sometimes difficult or inappropriate to adopt the standard surgical steps of adult laparoscopic procedures in pediatric patients because of the inevitably smaller anatomical structures and confined intra-abdominal working space. During laparoscopic Nissen fundoplication difficulties are usually encountered, especially when dissecting the diaphragmatic crura, creating the retroesophageal window, and repairing the crura. Thus, we devised a technique to accomplish these steps in pediatric patients. Both crural dissection and repair are approached from the left side of the esophagus and the port configuration for the laparoscope and other instruments is altered, providing better surgical exposure and easier handing of the instruments, even in very small patients. We describe this technique in detail and our results.

Adolescent↗

PubMed2003

Laparoscopic liver biopsy performed safely in a child with hepatic dysfunction: report of a case.

We performed laparoscopic liver biopsy in a 10-year-old girl with acute myelocytic leukemia and coagulopathy. Each biopsy was taken under laparoscopic ultrasound (LUS) guidance, and hemostasis was achieved with an argon beam coagulator (ABC). These instruments were introduced through one 10/12-mm port, which also allowed the insertion of surgical gauze for direct compression. By using LUS, ABC, and one full-sized working port, laparoscopic liver biopsy becomes a viable and safer alternative, even for children with coagulopathy.

Biopsy↗

PubMed2003

Beneficial effects of n-9 eicosatrienoic acid on experimental bowel lesions.

PURPOSE: Dietary fortification of n-9 polyunsaturated fatty acids (PUFA) or 5,8,11-eicosatrienoic acid (ETrA) as well as n-3 PUFA might contribute to the suppression of leukotriene B4 (LTB4) synthesis and thereby reduce inflammatory bowel lesions. As a result, the effect of an ETrA-enriched diet on experimental bowel lesions was examined in this study. METHODS: In Expt. 1, rats were freely fed either an ETrA-enriched or a standard diet. After 7 days of feeding, acute bowel lesions were induced by the subcutaneous injection of 10 mg/kg indomethacin. In Expt. 2, chronic bowel lesions were made by performing subcutaneous injections of 7.5 mg/kg indomethacin twice. After the first injection, the rats were freely fed either an ETrA-enriched or a standard diet for 7 days. RESULTS: In both experiments, the rats fed an ETrA-enriched diet showed increased levels of ETrA in the plasma and intestinal mucosa, and a decreased inflammation score. However, there was no significant decrease in plasma and intestinal mucosal LTB4 in the ETrA-enriched diet-fed rats. CONCLUSION: These results suggest that the dietary supplementation of ETrA may have both prophylactic and therapeutic effects on experimentally produced bowel lesions. Further investigations are necessary to clarify the effects of ETrA on bowel lesions and its mechanisms.

8,11,14-Eicosatrienoic Acid↗

PubMed2003

Laparoscopically assisted surgery for congenital gastric or duodenal diaphragm in children.

Presented are our recent experiences with successful laparoscopically assisted surgery in two children with congenital gastric or duodenal diaphragm. Laparoscopy was used as an adjunct in performing the following surgical procedures: (1) inspection of the entire bowel, (2) identification and evaluation of the involved site, and (3) mobilization and exteriorization of the involved site. A minimal transverse incision was made for exteriorization. Extracorporeal removal of the diaphragm was followed by pyloroplasty or duodenoplasty. Each patient had a rapid and uncomplicated recovery with complete resolution of the symptoms. Laparoscopically assisted surgery may be a valuable modality in pediatric patients with congenital gastric or duodenal diaphragm. It allows better assessment of the entire bowel, minimizing the disfiguring and morbid abdominal incisions, without impeding the effectiveness of the planned operation. Avoidance of full-scale laparotomy may decrease the risk of future adhesions. These advantages seem attractive especially for children with longer life expectancy.

Child↗

PubMed2002

Amino acid transport in a human neuroblastoma cell line is regulated by the type I insulin-like growth factor receptor.

Insulin-like growth factor I (IGF-I) and IGF-II stimulate cancer cell proliferation via interaction with the type I IGF receptor (IGF-IR). We put forward the hypothesis that IGF-IR mediates cancer cell growth by regulating amino acid transport, both when sufficient nutrients are present and when key nutrients such as glutamine are in limited supply. We examined the effects of alphaIR3, the monoclonal antibody recognizing IGF-IR, on cell growth and amino acid transport across the cell membrane in a human neuroblastoma cell line, SK-N-SH. In the presence of alphaIR3 (2 micro/ml), cell proliferation was significantly attenuated in both control (2 mM glutamine) and glutamine-deprived (0 mM glutamine) groups. Glutamine deprivation resulted in significantly increased glutamate (system X(AG)(-)), MeAIB (system A), and leucine (system L) transport, which was blocked by alphaIR3. Glutamine (system ASC) and MeAIB transport was significantly decreased by alphaIR3 in the control group. Addition of alphaIR3 significantly decreased DNA and protein biosynthesis in both groups. Glutamine deprivation increased the IGF-IR protein on the cell surface. Our results suggest that activation of IGF-IR promotes neuroblastoma cell proliferation by regulating trans-membrane amino acid transport.

Amino Acids↗

PubMed2002

Gut glutamine metabolism at different stages of sepsis in rats.

PURPOSE: To investigate gut glutamine metabolism and determine the effects of glutamine supplementation in different stages of sepsis in a rat model. METHODS: Sepsis was induced by cecal ligation and puncture (CLP), and control rats underwent a sham operation. In the first experiment, a continuous infusion of normal saline was started at the end of the operation. Intestinal blood flow, glutamine concentrations of the abdominal aorta and superior mesenteric vein (SMV) were measured, and gut glutamine extraction and flux were calculated 5 h after the sham operation, and 5 and 20 h after CLP, being groups Ia ( n = 9), Ib ( n = 8), and Ic ( n = 8), respectively. In the second experiment, animals received a continuous infusion of alanyl-glutamine instead of normal saline and were divided into groups IIa ( n = 8), IIb ( n = 8), and IIc ( n = 6). The same parameters were measured in each group and compared with those of the corresponding group in the first experiment. RESULTS: In the first experiment, no significant difference in SMV blood flow was seen among the groups. The arterial glutamine concentration was increased in group Ic ( P < 0.05) compared with that in groups Ia and Ib. Gut glutamine extraction was significantly increased in group Ib ( P < 0.01) and significantly decreased in group Ic ( P < 0.05) compared with that in group Ia. In the second experiment, gut glutamine flux was significantly increased in group Ilb ( P < 0.01) compared with that in group Ib, but the increase did not reach statistical significance between groups Ia and IIa or between groups Ic and IIc. CONCLUSION: These results indicate that intestinal glutamine uptake is increased and glutamine utilization is enhanced by glutamine supplementation in early sepsis.

Animals↗

PubMed2002

Effects of isolated small bowel transplantation on liver dysfunction caused by intestinal failure and long-term total parenteral nutrition.

It has not been fully determined whether isolated small bowel transplantation (ISBTx) can reverse liver dysfunction caused by intestinal failure requiring long-term total parenteral nutrition (TPN). A boy with congenital microvillus inclusion disease presented with vomiting and severe diarrhea since the first day of life and had been managed by TPN since then. He suffered from catheter-related sepsis several times. At 14 yr of age he developed progressive hepatosplenomegaly with thrombocytopenia and coagulopathy. He underwent ISBTx with an ileal graft from his blood-identical grandmother at the age of 16 yr. Oral feeding was started on the 14th day after ISBTx and gradually increased. TPN was completely withdrawn after 5 months. Liver was palpated 5 cm below the costal margin before ISBTx, while it became non-palpable 5 months after ISBTx. Serum liver enzyme levels and prothrombin time normalized in the 5 months following ISBTx. Liver biopsy showed marked steatosis, slight cholestasis, and mild bridging fibrosis before ISBTx. Although histological examination of liver biopsy revealed complete disappearance of steatosis 7 and 11 months after ISBTx, liver fibrosis remained unchanged. This clinical experience has shown that although steatosis and cholestasis are reversible after successful ISBTx and withdrawal of TPN, liver fibrosis may remain unchanged.

Adolescent↗

PubMed2002

Evaluation of indexes of in vivo manganese status and the optimal intravenous dose for adult patients undergoing home parenteral nutrition.

BACKGROUND: There are no accurate indexes for determining the status of manganese in humans, and there is no clear recommended daily dose of this essential trace element to be administered in total parenteral nutrition solutions. OBJECTIVE: The objectives were to evaluate accurate indexes of manganese status and elucidate the optimal manganese dose to be administered to adult patients undergoing home parenteral nutrition. DESIGN: Patients were administered total parenteral nutrition solutions providing 0, 1, 2, or 20 micromol Mn/d according to an on-off design, after which manganese concentrations in whole blood and plasma were determined. Magnetic resonance imaging (MRI) was performed to determine the intensity on T(1)-weighted images (MRI intensity) and T(1) values in the globus pallidus. Hematologic and biochemistry tests were also performed. RESULTS: High degrees of correlation were found between whole-blood manganese concentrations and both MRI intensity (r = 0.7728) and T(1) values (r = -0.7519) in the globus pallidus. A strong negative correlation was found between MRI intensity and T(1) values (r = -0.8407). The dose of 1 micromol Mn/d caused no change in MRI intensity or T(1) values, and the whole-blood manganese concentration remained within the normal range in all patients. CONCLUSIONS: Whole-blood manganese concentrations and MRI intensity and T(1) values in the globus pallidus are useful indexes of the status of manganese in humans. The optimal dose of manganese may be 1 micromol/d for adult patients undergoing home parenteral nutrition.

Adolescent↗

PubMed2002

Characterization of L-glutamine transport by a human neuroblastoma cell line.

This study characterized the Na+-dependent transport of L-glutamine by a human neuroblastoma cell line, SK-N-SH. The Na+-dependent component represented >95% of the total glutamine uptake. Kinetic studies showed a single saturable high-affinity carrier with a Michaelis constant (K(m)) of 163 +/- 23 microM and a maximum transport velocity (Vmax) of 13,713 +/- 803 pmol x mg protein(-1) x min(-1). Glutamine uptake was markedly inhibited in the presence of L-alanine, L-asparagine, and L-serine. Li+ did not substitute for Na+. These data show that L-glutamine is predominantly taken up through system ASC. Glutamine deprivation resulted in the decrease of glutamine transport by a mechanism that decreased Vmax without affecting K(m). The expression of the system ASC subtype ASCT2 decreased in the glutamine-deprived group, whereas glutamine deprivation did not induce changes in system ASC subtype ASCT1 mRNA expression. Adaptive increases in Na+-dependent glutamate, Na+-dependent 2-(methylamino)isobutyric acid, and Na+-independent leucine transport were observed under glutamine-deprived conditions, which were completely blocked by actinomycin D and cycloheximide. These mechanisms may allow cells to survive and even grow under nutrient-deprived conditions.

Amino Acid Transport System ASC↗

PubMedDate not supplied

Alanyl-glutamine-supplemented parenteral nutrition prevents intestinal ischemia-reperfusion injury in rats.

BACKGROUND: Intestinal ischemia-reperfusion (I/R) injury plays an important role in the pathogenesis of systemic inflammation and multiple-organ failure. We studied whether glutamine, the primary fuel of the small intestine, prevents intestinal mucosal damage after intestinal I/R in rats. METHODS: Rats were randomly divided into 4 groups: a sham-standard amino acid (SAA) group (n = 8); a sham-glutamine (Gln) group (n = 8); an I/R-SAA group (n = 10); and an I/R-Gln group (n = 9). Alanyl-glutamine solution was produced by replacing 36% of the total amino acid nitrogen with Gln. The superior mesenteric artery was ligated. After 60 minutes of ischemia, reperfusion was initiated and infusion was started. After 24-hour reperfusion, the intestinal segment was removed for morphological and biochemical analysis, and blood samples were drawn from the portal vein. Fluorescein isothiocyanate-conjugated dextran 70,000 (FITC-dextran) was infused into the duodenum 2 hours before animal death. RESULTS: In the I/R-SAA group, extensive epithelial sloughing and mucosal ulceration of villous tips were observed, whereas these findings did not occur in the I/R-Gln group. Mucosal wet weight, DNA, and protein content decreased significantly in the I/R-SAA group compared with the sham-SAA group and increased significantly in the I/R-Gln group compared with the I/R-SAA group. Plasma FITC-dextran significantly increased in the I/R-SAA group compared with the sham-SAA group, but the plasma level in the I/R-Gln group was comparable with that of each sham group. Mucosal glutaminase activity significantly increased in both the I/R-SAA and I/R-Gln groups compared with the sham-SAA and sham-Gln groups, respectively. CONCLUSIONS: Alanyl-glutamine protects against morphologic and functional mucosal injury after intestinal I/R in rats.

Animals↗

PubMedDate not supplied

A modular laparoscopic training program for pediatric surgeons.

OBJECTIVES: A structured endoscopic training program for pediatric surgeons has not yet been established. This study was conducted to develop a modular training program (MTP) for pediatric surgeons and to evaluate its effectiveness for surgeons with and without previous experience in laparoscopic surgery. METHODS: Nine pediatric surgeons participated in the study. They were divided into 2 groups: group A (n=4), surgeons who had experienced more than 10 cases of laparoscopic surgery prior to MTP; group B (n=5), those who had experienced fewer than 10 cases. They participated in a standardized MTP workshop, which consisted of 2 "see-through" and 3 "laparoscopic" tasks. Each participant's psychomotor skills were evaluated objectively before and after MTP with a computer-generated virtual simulator and were evaluated for precision, efficiency, and speed. RESULTS: In participants, speed was significantly enhanced after MTP. In group A, no differences were observed after MTP, whereas significant improvements were noted in efficiency and speed after MTP in group B. Before MTP, efficiency was significantly higher in group A than in group B; however, no difference remained between the 2 groups after MTP. CONCLUSIONS: MTP is effective for nonlaparoscopic pediatric surgeons to become familiar with basic endoscopic skills.

Adult↗