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Biomedical subjects

N Hamada

Publications and source records attributed to N Hamada.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mucosal damage and recovery of the intestine after prolonged preservation and transplantation in dogs.

BACKGROUND: Although much is known about the mucosal damage that occurs after intestinal warm ischemia and reperfusion and its recovery, little is known about the effect of cold preservation and transplantation on the mucosa. We studied the electrophysiological, biochemical, and histological changes of the intestinal mucosa after preservation for 24 hr and subsequent transplantation. METHODS: The small intestines from adult mongrel dogs were harvested. The intestines were orthotopically autotransplanted immediately (control group) or after preservation for 24 hr (preservation group). Jejunal and ileal tissues were taken before harvesting, at the end of preservation, 1 hr after reperfusion, and on postoperative days 3, 7, 14, and 28. The Ussing chamber method was used to study the electrophysiologic changes. Tissue maltase, diamine oxidase, and ornithine decarboxylase were measured. A histological analysis was also performed. RESULTS: Control group grafts showed no evident deterioration in electrophysiology, biochemistry, or morphology. In contrast, preservation group grafts exhibited electrophysiological and biochemical degradation, complete denudation of the villi, and crypt injury (especially in the ileum) after reperfusion. Electrophysiologic function and the mucosa biochemical marker recovered within 3 days in the jejunum and within 7-14 days in the ileum; however, histological recovery of mucosal injury required 28 days in the jejunum and more than 28 days in the ileum. CONCLUSIONS: Our study showed that despite severe destruction of mucosal integrity by prolonged preservation and transplantation, the intestinal mucosa has an enormous regenerative capacity. Our study also showed that regeneration was more pronounced in the jejunum than in the ileum.

Animals↗
PubMed2001

Contribution of serotonin to liver injury following canine small-intestinal ischemia and reperfusion.

Intestinal ischemia and reperfusion (I/R) has been shown to be associated with multiple organ damages. Serotonin (5-hydroxytriptamine; 5-HT), which is synthesized in the enterochromaffin cells in the intestine and stored in platelets, is known to play an important role in platelet aggregation and vasoconstriction and may ultimately enhance such organ injuries. The purpose of this study was to investigate the association between liver damage and 5-HT levels in the liver after intestinal I/R. The entire canine small intestine, isolated on a vascular pedicle that consisted of the proximal superior mesenteric artery and superior mesenteric vein, was subjected to 4-h ischemia by clamping these vessels and the marginal arteries supplying the proximal and distal ends of the small intestine. Hepatic blood flow, liver tissue blood flow, bile flow rate, and hepatic venous ketone body ratio (HVKBR) were measured before and at the end of intestinal ischemia and at 5, 15, and 30 min, and 1 and 2 h after reperfusion. 5-HT levels in plasma of the portal vein and hepatic vein were assayed at the same intervals. Time-matched, sham-operated animals served as controls. Intestinal I/R significantly decreased the liver tissue flow, bile flow rate, and HVKBR. Compared to those in controls, 5-HT levels in the portal vein and hepatic vein were markedly increased after reperfusion. Furthermore, intravenous administration of 5-HT receptor antagonists attenuated the liver dysfunction after intestinal reperfusion. These results suggest that intestinal I/R induces continuous disturbance of hepatic microcirculation, leading to liver dysfunction, and that 5-HT may be implicated as one of the mediators of liver dysfunction after intestinal I/R.

Animals↗
PubMed2001

Obstructive jaundice caused by lymphatic remetastasis from the hepatic metastasis of rectosigmoid cancer.

The significant benefit of performing hepatic resection for hepatic metastases from colorectal primary cancers is well established; however, the effectiveness of dissection of the lymph nodes draining the liver remains uncertain. Herein, we report the case of a 52-year-old man who was found to have obstructive jaundice caused by lymphatic remetastasis from the hepatic metastasis of primary rectosigmoid cancer. He had previously undergone a high anterior resection for the rectosigmoid cancer, in April 1990, and a hepatic resection for metastasis was done in March 1994. When the hepatic resection was carried out, dissection of the regional lymph nodes of the liver (i.e., the nodes in the hepatoduodenal ligament) was not performed because no obvious metastatic nodes were identified. Three years after the hepatic resection, enlarged lymph nodes compressing the extrahepatic bile duct from outside were identified by cholangiography and computed tomography (CT). Because radiological studies were unable to determine the lesion capable of metastasizing to these nodes, they were diagnosed as remetastasized lymph nodes from the hepatic metastasis that had been resected 3 years earlier. The lymphatic remetastases were intractable to treatment, and the patient finally died of hepatic failure and malignant cachexia. This case serves to demonstrate that lymphatic dissection of the regional lymph nodes may need to be taken into consideration when resection of hepatic metastases from colorectal cancers is performed.

Cholestasis↗
PubMed2001

Dibenzofurans from the cultured lichen mycobionts of Lecanora cinereocarnea.

From the cultures of the spore-derived mycobionts of the lichen Lecanora cinereocarnea, five dibenzofurans, 3,7-dihydroxy-1,9-dimethyldibenzofuran, 2-chloro-3,7-dihydroxy-1,9-dimethyldibenzofuran, 2,8-dichloro-3,7-dihydroxy-1,9-dimethyldibenzofuran, 3-hydroxy-7-methoxy-1,9-dimethyldibenzofuran, and 2-chloro-7-hydroxy-3-methoxy-1,9-dimethyldibenzofuran, were isolated. Their structures were determined by spectroscopic methods.

Benzofurans↗
PubMed2001

Frequency of appearance of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) in Graves' disease patients treated with propylthiouracil and the relationship between MPO-ANCA and clinical manifestations.

OBJECTIVE: Myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-positive vasculitis has been reported in patients with Graves' disease who were treated with propylthiouracil (PTU). The appearance of MPO-ANCA in these cases was suspected of being related to PTU because the titres of MPO-ANCA decreased when PTU was stopped. Nevertheless, there have been no studies on the temporal relationship between the appearance of MPO-ANCA and vasculitis during PTU therapy, or on the incidence of MPO-ANCA in untreated Graves' disease patients. Therefore, we sought to address these parameters in patients with Graves' disease. PATIENTS: We investigated 102 untreated patients with hyperthyroidism due to Graves' disease for the presence of MPO-ANCA, and for the development vasculitis after starting PTU therapy. Twenty-nine of them were later excluded because of adverse effects of PTU or because the observation period was less than 3 months. The remaining 73 patients (55 women and 18 men), all of whom were examined for more than 3 months, were adopted as the subjects of the investigation. The median observation period was 23.6 months (range: 3-37 months). MEASUREMENTS: MPO-ANCA was measured at intervals of 2-6 months. RESULTS: Before treatment, the MPO-ANCA titres of all 102 untreated Graves' disease patients were within the reference range (below 10 U/ml). Three (4.1%) of the 73 patients were positive for MPO-ANCA at 13, 16 and 17 months, respectively, after the start of PTU therapy. In two of them, the MPO-ANCA titres transiently increased to 12.8 and 15.0 U/ml, respectively, despite continued PTU therapy, but no vasculitic disorders developed. In the third patient, the MPO-ANCA titre increased to 204 U/ml and she developed a higher fever, oral ulcers and polyarthralgia, but the symptoms resolved 2 weeks after stopping PTU therapy, and the MPO-ANCA titre decreased to 20.7 U/ml by 4 months after discontinuing PTU. CONCLUSIONS: PTU therapy may be related to the appearance of MPO-ANCA, but MPO-ANCA does not appear to be closely related to vasculitis.

Adolescent↗
PubMed2001

Influenza virus RNA polymerase PA subunit is a novel serine protease with Ser624 at the active site.

BACKGROUND: Influenza virus RNA polymerase is a multifunctional enzyme that catalyses both transcription and replication of the RNA genome. The function of the influenza virus RNA polymerase PA subunit in viral replication is poorly understood, although the enzyme is known to be required for cRNA --> vRNA synthesis. The protease related activity of PA has been discussed ever since protease-inducing activity was demonstrated in transfection experiments. RESULTS: PA protein was highly purified from insect cells infected with the recombinant baculovirus carrying PA cDNA, and a novel chymotrypsin-type serine protease activity was identified with the synthetic peptide, Suc-LLVY-MCA, in the PA protein. [3H]DFP was crosslinked with PA and a mutational analysis revealed that serine624 was as an active site for the protease activity. CONCLUSIONS: These results constitute the demonstration of protease activity in PA subunit of the influenza virus RNA polymerase complexes.

Amino Acid Sequence↗
PubMed2001

Molecular evolution of human echovirus 9 isolated from patients with aseptic meningitis in northern Kyushu during the summer of 1997.

An epidemic of aseptic meningitis caused by human echovirus 9 (E-9) occurred in the summer of 1997 in northern Kyushu, Japan. Sequences of genome position 2504-3358, which encoded a part of VP1, of the nine isolated viruses were determined. An RGD motif and B-C loop were found in all. They were almost identical and closely related to the virulent strain Barty.

Amino Acid Sequence↗
PubMed2001

Role of cellulose-binding domain of exocellulase I from white rot basidiomycete Irpex lacteus.

The core fragment (designated P-42), devoid of the cellulose-binding domain (CBD) in the C-terminus and prepared from Irpex lacteus exocellulase I (Ex-1), was isolated by limited proteolysis using papain. Both the hydrolytic activity and binding ability of the isolated P-42 toward insoluble cellulose were lower than those of the native Ex-1, whereas Ex-1 and P-42 showed similar hydrolytic activities toward soluble substrates. These results indicate that the CBD of I. lacteus Ex-1 is the important domain which could enhance hydrolytic activity and binding ability of the enzyme toward insoluble cellulose. In addition, the isolated P-42 was different from the native Ex-1 in terms of enzymatic properties such as pH and temperature stabilities. These differences in stability, with regard to pH and temperature, between P-42 and the native Ex-1 are probably due to the O-linked sugar chains existing in the linker region.

Journal Article↗
PubMed2001

Stomach content analyses of Simulium perflavum Roubaud 1906 (Diptera: Simuliidae) larvae from streams in Central Amazônia, Brazil.

Stomach contents of Simulium perflavum Roubaud larvae were analyzed and compared with plankton and periphyton collected in five streams, in Central Amazonia (Manaus and Presidente Figueiredo counties), in Sep./Oct.1996 (dry season) and Feb./Mar. 1997 (rainy season). A total of 1,400 last-instar larvae were dissected; the stomach contents were analyzed using different methods: fresh and after oxidation. A total of 87 taxa (algae, diatoms and rotifers) were found in the stomach contents. In each stream, qualitative samples of plankton and periphyton were collected; these were mounted between slides and cover slips. A total of 94 taxa of plankton and 54 taxa of periphyton were collected. One species of Rotifera was present in the stomach contents, plankton and periphyton. Cluster analysis based on species composition of the organisms present in the stomach contents grouped the streams into two major groups, each belonging to a different drainage area. Correlations based on presence/absence of species of microalgae in the stomach contents, plankton and periphyton indicated significant associations (p<0.05) between stomach contents and plankton and between plankton and periphyton (z test); the Sorensen coefficient and cluster analysis corroborate the same associations.

Animals↗
PubMed2001

Morphometric comparison of Simulium perflavum larvae (Diptera: Simuliidae) in relation to season and gender in Central Amazônia, Brazil.

Number of larval instars, age structure and environmental effects on these parameters represent basic information in the study of insect population biology. When species have economic importance, this information is essential in order to choose the best period to apply different control methods and to determine the stages of the life cycle of the insect that are most susceptible to each treatment. The family Simuliidae has many species of medical/veterinary importance in the world, and some studies in the temperate region have suggested that the number of larval instars and the larval size can vary according to the season, gender and some environmental factors, such as temperature and diet. This study, with the zoophilic species Simulium perflavum Roubaud, is the first in the Neotropics observing some of these factors and will serve as a template for other species of medical importance in the region. S. perflavum larvae were collected in five streams in Central Amazônia (Manaus and Presidente Figueiredo counties, State of Amazonas), in Sept./Oct. 1996 (dry season) and Feb./Mar. 1997 (rainy season). These larvae were measured (lateral length of head capsule and width of cephalic apodema) to determine the number of larval instars (n=3985), to compare the larval size between seasons and genders (last and penultimate larval instars, n=200). Seven larval instars were determined for this species using frequency distributions, t-tests and Crosbýs growth rule. Significant differences were not detected (t-test, p>0.05) in larval size between seasons and genders. Our results differ from some found in temperate regions suggesting that in the Neotropical region the larval size in different seasons and different genders remains constant, although some environmental parameters, such as diet, change depending on the season.

Animals↗
PubMed2001

Black flies (Diptera: Simuliidae) of French Guiana: cytotaxonomy and a preliminary list of species.

The objectives of the present study were to broaden the survey of simuliid species in French Guiana and to cytologically analyze the species in the Simulium perflavum species group. Twelve species of Simulium were collected from which S. goeldii, S. quadrifidum, S. trombetense, S. near incrustatum, S. metallicum (s.l.) sp1, S. metallicum (s.l.) sp2 and S. ochraceum (s.l.) are reported for the first time for this region. The only species collected in the S. perflavum group was S. rorotaense; 34 larvae of this species were cytologically analyzed, all of which had the standard sequence. S. metallicum (s.l.), S. ochraceum (s.l.), S. guianense (s.l.) and S. oyapockense (s.l.) are involved with transmission of onchocerciasis in Central and South America, however, in French Guiana these species were not found biting humans during the sampling period. With the few collections made during this study, we increase the number of simulid species known in French Guiana from 6 to 13. It is clear that more simuliid species can be expected to be found when more sampling is done, including collections in other ecoregions in French Guiana.

Animals↗
PubMed2001

Occurence of larval Culicidae (Diptera) in water retained in Aquascypha hydrophora (Fungus: Stereaceae) in Central Amazônia, Brazil.

The community structure of insects, especially mosquito larvae, in water held in the fungus Aquascypha hydrophora (Berk.) Reid (Stereaceae) is reported. The study was done in the Adolpho Ducke Forest Reserve, 26 km east of Manaus, AM, Brazil, from September 1998 through November 1999. The most abundant entomofauna were immature Culicidae (n = 121) 91.7%, followed by adult Dytiscidae (n = 3) 2.3%, immature Chironomidae (n = 5) 3.8% and immature Tipulidae (n = 3) 2.3%. Culicidae associated with A. hydrophora comprised species of the subfamilies Anophelinae and Culicinae.

Animals↗
PubMed2001

[Studies of intraoperative plateletapheresis in cardiovascular surgery].

We evaluated the effect of intraoperative plateletapheresis (IPA) on platelet dysfunction associated with cardiopulmonary (C-P) bypass in 49 patients for open heart or great vessel surgery. Autologous platelet concentrated (PC) (16.6 +/- 6.1 units) was collected before the start of C-P bypass and was reinfused after protamine administration. Platelet aggregability after PC reinfusion was significantly greater in IPA group (n = 13) than in non-IPA group (n = 15). Platelet count and ionized calcium level were lower in the IPA group temporarily after PC collection. No differences were noted in hemodynamic variables, WBC count and hemoglobin between the two groups. Plasma IL-6, which increased slightly after PC collection, showed a great increase after C-P bypass in both IPA (n = 8) and non-IPA (n = 8) groups. In in vitro experiments, platelet aggregability was reduced with the increase of centrifugal force over 800 x g during PC separation (n = 10) and with the prolongation of PC preserving time over 4 hours (n = 11). The result of this study demonstrates the significance of plateletapheresis in post-bypass platelet function and hemostasis, although further improvements are needed for collection and preservation of PC.

Aged↗
PubMed2000

Purification and characterization of a novel secondary fimbrial protein from Porphyromonas gingivalis strain 381.

We previously reported the existence of two different kinds of fimbriae expressed by Porphyromonas gingivalis ATCC 33277. In this study, we isolated and characterized a secondary fimbrial protein from strain FPG41, a fimA-inactivated mutant of P. gingivalis 381. FPG41 was constructed by a homologous recombination technique using a mobilizable suicide vector, and failed to express the long fimbriae (41-kDa fimbriae) that were produced on the cell surface of P. gingivalis 381. However, short fimbrial structures were observed on the cell surface of FPG41 by electron microscopy. The fimbrial protein was purified from FPG41 by DEAE-Sepharose CL-6B column chromatography. The secondary fimbrial protein was eluted at 0.15 M NaCl, and the molecular mass of this protein was approximately 53 kDa as estimated by SDS-PAGE. An antibody against the 53-kDa fimbrial protein reacted with the short fimbriae of the FPG41 and the wild-type strain. However, the 41-kDa long fimbriae of the wild-type strain and the 67-kDa fimbriae of ATCC 33277 did not react with the same antibody. Moreover, the N-terminal amino acid sequence of the 53-kDa fimbrial protein showed only 2 of 15 residues that were identical to those of the 41-kDa fimbrial protein. These results show that the properties of the 53-kDa fimbriae are different from those of the 67-kDa fimbriae of ATCC 33277 as well as those of the 41-kDa fimbriae.

Amino Acid Sequence↗
PubMed2000

Inhibition of influenza virus replication in cultured cells by RNA-cleaving DNA enzyme.

Influenza virus replication has been effectively inhibited by antisense phosphothioate oligonucleotides targeting the AUG initiation codon of PB2 mRNA. We designed RNA-cleaving DNA enzymes from 10-23 catalytic motif to target PB2-AUG initiation codon and measured their RNA-cleaving activity in vitro. Although the RNA-cleaving activity was not optimal under physiological conditions, DNA enzymes inhibited viral replication in cultured cells more effectively than antisense phosphothioate oligonucleotides. Our data indicated that DNA enzymes could be useful for the control of viral infection.

Animals↗
PubMed2000

Abdominal multivisceral transplantation in pigs.

We investigated the technical aspects of porcine abdominal multivisceral transplantation, in terms of pathophysiological features in animals given no immunosuppresant. The splanchnic organs of the donor animal were flushed in situ with University of Wisconsin solution via the abdominal aorta, using a pump. After a relatively short period of cold storage in saline, multivisceral grafts, including the liver, pancreas, and gastrointestinal tract, were transplanted orthotopically. Of the 18 recipient pigs that underwent the operation, 9 (50%) died within 24 h, mainly because of respiratory insufficiency (n = 5) and circulatory shock (n = 3). Three animals (17%) were lost to acute renal failure between the second and fifth postoperative days. Six pigs (33%) survived for more than 1 week, and the causes of death in these animals were bowel obstruction (n = 1), pneumonia (n = 2), rejection of the intestinal graft (n = 2), and deterioration (n = 1). Although the results of this study were not satisfactory, abdominal multivisceral transplantation using pigs is practical and may lead to the possible resolution of various problems, in regard to the immunologic aspects and the interrelationship of transplanted complex organs.

Animals↗