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Biomedical subjects

K Gu

Publications and source records attributed to K Gu.

51 records · Page 3Linked to original sources
PubMed1995

Purification, characterization and specificity of chondroitin lyases and glycuronidase from Flavobacterium heparinum.

The chondroitin lyases from Flavobacterium heparinum (Cytophaga heparinia) have been widely used in depolymerization of glycosaminoglycan and proteoglycan chondroitin sulphates. Oligosaccharide products derived from chondroitin sulphate can be further degraded by glycuronidases and sulphatases obtained from the same organism. There has been no reported purification of these enzymes to homogeneity nor is there any information on their physical and kinetic characteristics. The absence of pure enzymes has resulted in a lack of understanding of the optimal conditions for their catalytic activity and their substrate specificity. This has limited the use of these enzymes as reagents for preparation of oligosaccharides for structure and activity studies. Reproducible schemes to purify a chondroitin AC lyase, a glycuronidase and chondroitin B lyase from Flavobacterium heparinum to apparent homogeneity are described. Chondroitin AC lyase (chondroitinase AC, EC 4.2.2.5), glycuronidase [chondro-(1-->3)-glycuronidase, no EC number] and chondroitin B lyase (chondroitinase B, no EC number) have M(r) values (assessed by SDS/PAGE) of 74,000, 41,800 and 55,200 respectively, and isoelectric points (determined by isoelectric focusing) of 8.85, 9.28 and 9.05 respectively. Chondroitin lyase AC and B contain pyroglutamic acid at their N-termini precluding their analysis by Edman degradation. Deblocking with pyroglutamate aminopeptidase facilitated the determination of their N-terminal sequences. The kinetic properties of these enzymes have been determined as well as the optimum conditions for their catalytic activity. The specificity of the glycouronidase, determined using 17 different disaccharide substrates, shows that it only acts on unsulphated or 6-O-sulphated 1-->3 linkages. The chondroitin lyases are both endolytic enzymes, and oligosaccharide mapping shows their expected specificity towards the chondroitin and dermatan sulphate polymers.

Amino Acids↗
PubMed1995

Ischemic preconditioning improves cardiac functional recovery following preservation with University of Wisconsin solution.

Single or multiple brief periods of regional or global ischemia and reperfusion prior to a prolonged ischemic insult showed cardioprotective effects. Although this phenomenon (ischemic preconditioning [IPC]) has been described in ischemic reperfusion models, the effect of IPC on heart preservation has not been previously reported. We, thus, investigated the effect of IPC on heart preservation. Hearts isolated from male Wistar rats (250-350 g) were mounted on a Langendorff apparatus to estimate baseline function (aortic flow, coronary flow, cardiac output, heart rate, systolic pressure, and rate pressure product). All hearts were divided into 5 groups. In groups 1 and 4, the hearts were subjected to 8 and 12 hr of preservation, respectively. The hearts in group 2 were subjected to a single 2.5-minute cycle of normothermic global ischemic episode (IPC) before 8 hr of preservation. In groups 3 and 5, the hearts were subjected to two 2.5-min IPC cycles and stored for 8 or 12 hr. The hearts were arrested with University of Wisconsin solution and stored at 4 degrees C. Following storage, the hearts were reperfused and measured postpreservative function to assess cardiac functional recovery. Lactate and troponin-T leakage in the coronary perfusate was also measured. In group 3, the treatment of two 2.5-min IPC cycles significantly increased cardiac output, but the treatment of single 2.5-min IPC cycle did not affect the result. In the extended preservation group (group 5), the recovery (%) of both coronary flow and cardiac output were significantly increased compared with group 4. Furthermore, lactate leakage was significantly reduced in groups 2 and 3. These results suggest that IPC improves cardiac functional recovery following simple cold storage and has cardioprotective effects in rat heart preservation.

Adenosine↗
PubMed1995

[A case report of left atrial free-floating ball thrombus in a patient without mitral valve disease].

A 77-year-old man who had a left atrial free-floating ball thrombus without mitral valve disease was operated. His electrocardiogram showed atrial fibrillation. Transesophageal echocardiography showed free-floating mass in dilated left atrium and intact mitral valve. Transesophageal echocardiogram was also useful for intra-operative management. At the operation, the mass proved to be a free-floating ball thrombus in the left atrium and the intact mitral valve was confirmed. The thrombus was removed, but we could not wean the patient from extra-corporeal circulation due to intra-operative myocardial infarction. Autopsy showed left ventricular hypertrophy and the focus of acute myocardial infarction in lateral wall and posterior wall of left ventricle. Furthermore, large organized thrombi were found in aorta and right main pulmonary artery. It was suggested that the patient had abnormal coagulative system or fibrolytic system preoperatively.

Aged↗
PubMed1995

[A successful operation for left atrial myxoma and mitral valve regurgitation with giant LA].

A 78-year-old woman was introduced to our clinic, complaining of orthopnea and severe appetite loss, and her performance status was evaluated as NYHA IV. Computed tomogram revealed a myxoma in left atrium (LA) as a low density area and MRI demonstrated a high intensity shadow. Left ventriculogram and color Doppler echocardiogram showed severe mitral valve regurgitation (MR) with giant LA. LA myxoma was completely resected through both LA-tomy and RA-tomy. The LA was plicated according to the method reported by Kawazoe, followed by a mitral valve replacement with SJM 25 mm, and a tricuspid annuloplasty according to the DeVega's method. The postoperative course was uneventful and her performance status improved to NYHA II at discharge. LA myxoma frequently causes secondary MR. In this case, however, the LA myxoma did not affect the function of mitral valve, judging from its size and position. There were a few reports about LA myxoma complicated with primary MR. We also confirmed that a LA plication was very useful for the treatment of giant LA to improve a respiratory failure.

Aged↗
PubMed1995

[A case of lung scar cancer with special pathohistological feature and high CA 19-9 level].

A 58-year-old woman complained of cough and fever. CX-P and chest CT revealed pneumonic shadow and serum CA 19-9 level was high. Since the malignant cells were found in the bronchial lavage fluid, the lower lobectomy of the left lung was done. Both macroscopically and microscopically, adenocarcinoma only existed in 2-3 mm width at the peripheral site of the scar lesion. The postoperative CA 19-9 values continued to be high, suggesting the recurrence of the cancer. After 23 months from the first operation, the upper lobe of the left lung was resected on the base of the similar findings in CX-P and chest CT. The histological finding of the specimen was compatible with the scar cancer described above. After the second operation, the serum CA 19-9 value decreased to normal. We reported a case of the lung scar cancer with special pathohistological feature.

Adenocarcinoma, Papillary↗
PubMed1995

[The diagnosis and treatment of benign esophagotracheo-bronchial fistula: a report of 26 cases].

Twenty six patients with esophagotracheal fistula or esophagobronchial fistula were treated from 1960 to 1991. There were 18 males and 8 females with age ranging from 19 to 69. Trauma and complication of esophageal diverticulum were the main causes of fistula. Among 23 patients surgically treated, 10 underwent direct repair, and 13 either closure of esophageal defect or tracheal or bronchial defect. The concomitant procedures were permanent tracheostomy, tracheal resection and reconstruction, pulmonary resection, thoracoplasty esophagectomy, and esophagogastric anastomosis. All patients resumed normal eating. Complications included paralysis of recurrent nerves, empyema, injury and ligation of subclavian artery, dehiscence of tracheal anastomosis, and contralateral pneumohydrothorax in each patient. Prognosis of 3 nonsurgical treatments of fistulas was poor. Surgical intervention should be done as soon as the diagnosis is established in order to minimize pulmonary complication.

Adult↗
PubMed1995

[Acute thrombosed aortic dissection--its clinical manifestation and treatment for Stanford A type].

Ten patients (mean age of 63 years old) with acute thrombosed aortic dissection (ATAD) have been evaluated among 31 aortic dissections during past 10 years (from 1985 to 1995). The six cases are Stanford A type and others are Stanford B type. The mean maximal diameter of aorta was 52 +/- 6 mm in Stanford A type and 41 +/- 4 mm in Stanford B type. The ratio of true lumen was 78 +/- 14% to that of whole horizontal section area in thrombosed type and 34 +/- 19% in opacified type dissection. We had chosen conservative treatment for all ATAD. However, five patients with Stanford A type dissection needed to be operated on in short term periods. Three patients were operated upon within three days from onset, and another two patients were operated on 34th and 37th day from onset, respectively. ATAD is firstly treated medically and its prognosis is generally well. However, we proposed here that the conservative treatment for ATAD, especially Stanford A type dissection, must be reconsidered because of our many operations for ATAD in the follow-up periods.

Acute Disease↗
PubMed1994

Action pattern of polysaccharide lyases on glycosaminoglycans.

The action pattern of polysaccharide lyases on glycosaminoglycan substrates was examined using viscosimetric measurements and gradient polyacrylamide gel electrophoresis (PAGE). Heparin lyase I (heparinase, EC 4.2.2.7) and heparin lyase II (no EC number) both acted on heparin in a random endolytic fashion. Heparin lyase II showed an ideal endolytic action pattern on heparan sulphate, while heparin lyase I decreased the molecular weight of heparan sulphate more slowly. Heparin lyase III (heparitinase, EC 4.2.2.8) acted endolytically only on heparan sulphate and did not cleave heparin. Chondroitin ABC lyase (chondroitinase ABC, EC 4.2.2.4) from Proteus vulgaris acted endolytically on chondroitin-6-sulphate (chondroitin sulphate C) and dermatan sulphate at nearly identical initial rates, but acted on chondroitin-4-sulphate (chondroitin sulphate A) at a reduced rate, decreasing its molecular weight much more slowly. Two chondroitin AC lyases (chondroitinase AC, both EC 4.2.2.5) were examined towards chondroitin-4- and -6-sulphates. The exolytic action of chondroitin AC lyase A from Arthrobacter aurescens on both chondroitin-4- and -6-sulphates was demonstrated viscosimetrically and confirmed using both gradient PAGE and gel permeation chromatography. Chondroitin AC lyase F from Flavobacterium heparinum (Cytophagia heparinia) acted endolytically on the same substrates. Chondroitin B lyase (chondroitinase B, no EC number) from F.heparinum acted endolytically on dermatan sulphate giving a nearly identical action pattern as observed for chondroitin ABC lyase acting on dermatan sulphate.

Arthrobacter↗
PubMed1994

[Screening of anti-inflammatory, immunosuppressive and antifertility components of Tripterygium wilfordii V. Effects of 7 diterpene lactone epoxide compounds on the proliferation of T and B lymphocytes in vitro].

The inhibitory effects and their IC50 values of Tripterygium wilfordii (TW) on T and B lymphocytes were assayed using mice splenocytes induced to proliferate by mitogens ConA and LPS in vitro. The results indicated that 6 compounds (T4,T7,T8,T9,T10,L2) and component T1 had significant inhibitory effects on the proliferation of lymphocytes in response to ConA and LPS. The inhibitory potencies of these compounds were in the range of 10(-5)-10(-9) micrograms/ml for both T and B cells, while those of T1 were 3.5 and 4.2 micrograms/ml, respectively. The IC50 values, from low to high, were in the following order: T10,T4,T8,L2,T7,T9 and T1, The dose-effect curves for LPS were to the right of ConA curves, though both were nearly parallel. The relative order of the IC50 values determined from ConA and LPS curves were also coincident. Another compound, T11, showed no suppressive effect on the proliferation of T and B lymphocytes induced by either mitogen, even when its concentration reached 50 micrograms/ml. The results suggest that the suppressive effects of the componends on the proliferation of T and B lymphocytes in vitro were direct and non-selective.

Animals↗
PubMed1993

Monoclonal antibodies prepared against heparin lyase I and their reactivity toward heparin lyase I, II and III.

1. Six different monoclonal IgG mouse antibodies to heparin lyase I from Flavobacterium heparinum were prepared. 2. The monoclonal antibodies were used to detect heparin lyases I, II and III by dot-blotting immunoassay and by Western blotting. 3. Individual antibodies showed different reactivity toward the three heparin lyases. 4. The reactivity of two of the monoclonal antibodies was destroyed by exposing heparin lyases to sodium dodecyl sulfate. 5. The antibodies can be used to rapidly distinguish between the three heparin lyases.

Animals↗
PubMed1993

Capillary electrophoresis to measure sulfoesterase activity on chondroitin sulfate and heparin derived disaccharides.

Capillary electrophoresis was used to assay sulfoesterase activity on sulfated disaccharides derived from chondroitin sulfate, dermatan sulfate and heparin. The three sulfoesterases studied were chondro-4-O-sulfatase (EC 3.1.6.9) and chondro-6-O-sulfatase (EC 3.1.6.10) from Proteus vulgaris and heparo-2-O-sulfatase from Flavobacterium heparinum. Capillary electrophoresis was used to analyse sulfated disaccharide before and after sulfoesterase treatment and a change in migration time was indicative of the presence of sulfoesterase activity. This assay was used both on purified sulfoesterases and on minor sulfoesterase contaminants present in other enzyme preparations. The high sensitivity of capillary electrophoresis permits the elimination of 35S-radiolabeled substrates normally required to assay sulfoesterases. The high resolution of capillary electrophoresis allows the use of this assay on impure enzyme preparations containing high protein concentrations.

Chondro-4-Sulfatase↗
PubMed1993

[Successful operation for two cases of an aneurysmal bone cyst of the rib].

An aneurysmal bone cyst involving the rib is very rare. A 43-year-old man and 49-year-old woman complained of pain and swelling on the chest. X-ray and CT revealed a local expansion and honeycomb lesion of the right 9th rib. Surgical excision of the rib were performed to remove the tumor completely. The histopathological examination revealed that the lesion consisted of many cavities filled with blood and trabecullae containing osteoid tissue and giant cells, showing it to be an aneurysmal bone cyst. Because of the potential for the rapid growth and difficulty in differentiation between benign and malignant rib tumor, an excisional biopsy should be considered for the treatment of an aneurysmal bone cyst of the rib.

Adult↗
PubMed1993

[Successful operation for isolated cardiac rhabdomyoma of the right atrium].

A 12-year-old girl has experienced palpitation and dizziness, and presented atrial flutter with maximal heart rate of 220/min. Two-dimensional echocardiogram and chest MRI revealed a mass attached to the inter-atrial septum. Complete excision of the tumor including the atrial septum was performed without damage to tricuspid valve. The interatrial septal defect was closed primarily. Histology of the tumor was compatible with cardiac rhabdomyoma. Sinus rhythm was present and no tachycardia occurred in the postoperative period. On the literature, only one case of isolated cardiac rhabdomyoma developing in the atrium was reported and this is considered as the oldest operative case in Japan.

Child↗