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N Isogai

Publications and source records attributed to N Isogai.

17 recordsLinked to original sources
PubMed2000

Experimental use of fibrin glue to induce site-directed osteogenesis from cultured periosteal cells.

The purpose of this study was to determine whether a combination of fibrin glue and cultured periosteal cells will result in new bone formation at heterotopic sites in nude mice. Growing cells and developing matrices surrounding periosteal explants from the diaphyses of radii of newborn calves were minced and mixed with fibrin glue in a syringe. The cell/matrix-fibrin glue admixture was then injected into the subcutaneous space on the dorsum of athymic nude mice. After 12 weeks of implantation, gross morphology and histologic investigations showed newly formed bone structures in all cell/matrix-fibrin glue admixtures, but none in fibrin glue injected alone and used as control samples. Osteopontin, a protein important in bone development, was identified by a Western blot assay of the cell/matrix-fibrin glue composite. This study supports the feasibility of initiating site-directed formation of bone structures at heterotopic tissue sites by means of injection of cultured periosteal cells and matrix in a fibrin glue carrier.

Animals↗
PubMed1999

Formation of phalanges and small joints by tissue-engineering.

BACKGROUND: This report describes the formation of small phalanges and whole joints from three types of bovine-cell sources transplanted onto biodegradable polymer matrices. The resulting structures had the shape and composition of human phalanges with joints. METHODS: Fresh bovine periosteum was wrapped around a copolymer of polyglycolic and poly-L-lactic acid. Separate sheets of polyglycolic acid polymer were then seeded with chondrocytes and tenocytes isolated from the shoulders of freshly killed calves. The gross form of a composite tissue structure was constituted in vitro by assembling the parts and suturing them to create models of a distal phalanx, a middle phalanx, and a distal interphalangeal joint. RESULTS: Subcutaneous implantation of the sutured composite tissues into athymic mice resulted in the formation, after twenty weeks, of new tissue with the shape and dimensions of human phalanges with joints. Histological examination revealed mature articular cartilage and subchondral bone with a tenocapsule that had a structure similar to that of human phalanges and joints. There was continuous cell differentiation at the ectopic site even after extended periods. CONCLUSIONS: These findings suggest that the formation of phalanges and small joints is possible with the selective placement of periosteum, chondrocytes, and tenocytes into a biodegradable synthetic polymer scaffold.

Animals↗
PubMed1999

[Tissue engineering].

The new field of tissue engineering, applies the principles of biology and engineering to the development of functional substitutes for the loss or failure of an organ or tissue. This article describes the previous challenges and present status of this interdisciplinary field.

Animals↗
PubMed1998

Creation of viable pulmonary artery autografts through tissue engineering.

BACKGROUND: "Repair" of many congenital cardiac defects requires the use of conduits to establish right ventricle to pulmonary artery continuity. At present, available homografts or prosthetic conduits lack growth potential and can become obstructed by tissue ingrowth or calcification leading to the need for multiple conduit replacements. Tissue engineering is an approach by which cells are grown in vitro onto biodegradable polymers to construct "tissues" for implantation. A tissue engineering approach has recently been used to construct living cardiac valve leaflets from autologous cells in our laboratory. This study assesses the feasibility of a tissue engineering approach to constructing tissue-engineered "living" pulmonary artery conduits. MATERIALS AND METHODS: Ovine artery (group A, n = 4) or vein (group V, n = 3) segments were harvested, separated into individual cells, expanded in tissue culture, and seeded onto synthetic biodegradable (polyglactin/polyglycolic acid) tubular scaffolds (20 mm long x 15 mm diameter). After 7 days of in vitro culture, the autologous cell/polymer vascular constructs were used to replace a 2 cm segment of pulmonary artery in lambs (age 68.4 +/- 15.5 days, weight 18.7 +/- 2.0 kg). One other control animal received an acellular polymer tube sealed with fibrin glue without autologous cells. Animals were sacrificed at intervals of 11 to 24 weeks (mean follow-up 130.3 +/- 30.8 days, mean weight 38.9 +/- 13.0 kg) after echocardiographic and angiographic studies. Explanted tissue-engineered conduits were assayed for collagen (4-hydroxyproline) and calcium content, and a tissue deoxyribonucleic acid assay (bis-benzimide dye) was used to estimate number of cell nuclei as an index of tissue maturity. RESULTS: The acellular control graft developed progressive obstruction and thrombosis. All seven tissue-engineered grafts were patent and demonstrated a nonaneurysmal increase in diameter (group A = 18.3 +/- 1.3 mm = 95.3% of native pulmonary artery; group V = 17.1 +/- 1.2 mm = 86.8% of native pulmonary artery). Histologically, none of the biodegradable polymer scaffold remained in any tissue-engineered graft by 11 weeks. Collagen content in tissue-engineered grafts was 73.9% +/- 8.0% of adjacent native pulmonary artery. Histologically, elastic fibers were present in the media layer of tissue-engineered vessel wall and endothelial specific factor VIII was identified on the luminal surface. Deoxyribonucleic acid assay showed a progressive decrease in numbers of cell nuclei over 11 and 24 weeks, suggesting an ongoing tissue remodeling. Calcium content of tissue-engineered grafts was elevated (group A = 7.95 +/- 5.09; group V = 13.2 +/- 5.48; native pulmonary artery = 1.2 +/- 0.8 mg/gm dry weight), but no macroscopic calcification was found. CONCLUSIONS: Living vascular grafts engineered from autologous cells and biodegradable polymers functioned well in the pulmonary circulation as a pulmonary artery replacement. They demonstrated an increase in diameter suggesting growth and development of endothelial lining and extracellular matrix, including collagen and elastic fibers. This tissue-engineering approach may ultimately allow the development of viable autologous vascular grafts for clinical use.

Animals↗
PubMed1997

Application of medical thermography to the diagnosis of Frey's syndrome.

BACKGROUND: In Frey's syndrome, the secretory parasympathetic fibers of the parotid gland are thought to communicate with the sympathetic nerve fibers of sweat glands and blood vessels of the skin following parotidectomy. Miscommunication results in subjective gustatory sweating and facial flushing, which appear early with postoperative mastication. In this study, we compared the efficacy of medical thermography to the Minor's starch-iodine test to determine the presence of gustatory sweating in Frey's syndrome. METHODS: Patients were considered to have Frey's syndrome if signs of gustatory sweating and localized skin flushing of the parotid region were present. In four patients who had undergone unilateral parotidectomy, gustatory sweating and facial flushing were present after gustatory stimulation, and the presence of Frey's syndrome was confirmed with Minor's starch test in all patients. Infrared thermography was then performed, and the same area measured. The contralateral side served as an internal control for each patient. RESULTS: Before gustatory stimulation, the isothermal pattern of the diseased side and the nonoperative side was similar. Stress thermography using a sialogogue (lemon, 3 mL) showed a cold spot at the operative site in all four patients with Frey's syndrome. The contralateral nonoperative side showed normal skin temperature distribution in all patients. Minor's test was positive in all patients. CONCLUSIONS: Thermography is a noninvasive, facile test that provides a qualitative visual analysis of the cutaneous capillary response in Frey's syndrome following parotid surgery.

Adenocarcinoma↗
PubMed1996

Clinical outcome of digital replantation using the fibrin glue-assisted microvascular anastomosis technique.

A series of 36 digital replants is reported in which microvascular anastomoses were each performed with four to six stitches and topically applied fibrin glue. Thirty-two digits survived, comparable to survival with conventional microvascular anastomosis. The average operative time per replanted digit was 3.2 hours, considerably less than documented with standard replantation technique (4.5 hours per digit). These clinical findings indicate that fibrin glue-assisted microvascular anastomosis does not compromise replant outcome and can reduce the operative time by reducing the number of microsutures that need to be placed in each anastomosis.

Adolescent↗
PubMed1995

Patterns of thermoregulation associated with cold intolerance after digital replantation.

Twelve patients with complete thumb amputations were analyzed to determine the interrelations between thermoregulation for pain and cold intolerance and sensory nerve recovery. Patients were examined at 3 months, 6 months, 1 year, and after 2 years following replantation. Medical thermography was introduced to assess postoperative circulation following digital replantation, while vasomotor tone was assessed by cold-stress plethysmography testing. Postoperative circulation was divided into two different patterns based upon skin temperature, the transition of which over time correlated well with sensory nerve recovery. Patients with cold intolerance showed a persistent vasoconstriction pattern, the cold change of which was objectively detected by thermography.

Adult↗
PubMed1995

[Massive and progressive hepatosplenomegaly caused by disseminated nontuberculous mycobacteriosis in a patient with acquired immunodeficiency syndrome].

A 28-year-old hemophilia A patient was admitted to our hospital in July, 1991 because of high fever, chronic diarrhea and anemia. The patient had been recognized as a asymptomatic carrier of human immunodeficiency virus (HIV) in 1985 and had developed Pneumocystis carinii pneumonia and had been diagnosed as acquired immunodeficiency syndrome (AIDS) in 1990. Hematologic laboratory examinations on admission revealed pancytopenia and a CD4+ cell count of 3/mm3. X-ray findings of chest and abdomen were normal and bacterial cultures of sputum, urine, blood, stool, cerebrospinal fluid and bone marrow yielded no pathogenic microorganisms. Microscopical examination of the stained specimens showed no acid-fast bacilli. On his fifth hospital day, his liver and spleen enlarged markedly and an abdominal CT scan obtained on the 13th day revealed high-grade hepatosplenomegaly. Administration of several kinds of antibiotics, antifungal agents, antiviral agents, antituberculous agents and gamma-globulin medicines did not relieve the symptoms. On the 28th day the patient had developed a subarachnoid hemorrhage and died five days later. Retrospectively all cultures for acid-fast bacilli of the specimens on his admission yielded nontuberculous mycobacteria. The bacteria were identified as Mycobacterium avium by polymerase chain reaction and his disease was eventually diagnosed as disseminated Mycobacterium avium complex (MAC) infection. The liver and spleen weighed 2,660 g and 1,840 g respectively at autopsy. Although hepatosplenomegaly is commonly recognized in AIDS patients with disseminated MAC infection, such massive and rapid enlargement has been rarely observed. This case study emphasize the importance of diagnosis and rapid treatment at the early stage of MAC infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Effect of hypertension on arterial structure and wound repair at the microvascular anastomosis site using stroke-prone spontaneously hypertensive rats (SHRSP).

Different processes of microvascular wound healing under hypertension in comparison to normotension have been suspected. To explore these differences at the site of anastomotic wound repair, we performed microvascular anastomoses of the femoral arteries in 12-week-old, stroke-prone hypertensive rats (SHRSP) whose maximum blood pressure reached 238 mm Hg and in normotensive age-matched Wistar Kyoto (WKY) rats. Morphologic changes under hypertension were examined via light microscopy. The arrangement and number of endothelial cells were examined using the en face silver staining technique. The plasma activity levels of factor XIII were also measured in each group. Transitional healing at the microvascular anastomosis site was evaluated via scanning electron microscopy. The extent of endothelial migration over the exposed media around the needle holes was determined using a computerized graphic analysis system. Histologic cross sections demonstrated a thickened media, with altered shape and arrangement of the smooth muscle cell nuclei in SHRSP arteries compared with WKY arteries. En face silver staining showed small and spindle-shaped endothelial cells with an irregular cell arrangement and distribution in SHRSP arteries relative to WKY arteries. Factor XIII was increased 36% over baseline in SHRSP rats postoperatively; this was significantly higher than the increase in WKY rats (P < 0.05). Although both SHRSP and WKY arteries had similar wound healing responses to microvascular anastomosis, endothelial cell migration over the exposed media was significantly accelerated in the SHRSP rats.

Anastomosis, Surgical↗
PubMed1993

[Fluctuation of plasma levels of fibrinogen degradation products, fibrin degradation products and total fibrin/fibrinogen degradation products in patients with DIC].

Ten patients with disseminated intravascular coagulation syndrome (DIC) were analyzed using three enzyme linked immunosorbent assays (ORGANON TEKNIKA, Belgium) for fibrin degradation products (FbDP), fibrinogen degradation products (FgDP) and total fibrin/fibrinogen degradation products (TDP). A significant elevation in each parameter and a significant depression of FgDP/FbDP (g/b) ratio were observed in the patients in early stage of DIC, comparing with normal individuals (p < 0.001 and p < 0.01). These results suggested that both fibrinolysis and fibrinogenolysis were marked accelerated, with a superiority in fibrinolysis in those patients. The levels of these parameters decreased and the g/b ratio increased with the passage of the clinical courses in five patients who were improved. Although in five deteriorated cases, the levels were kept high and their g/b ratio showed low continuously. These findings suggested that separated monitoring of fibrinolysis or fibrinogenolysis was useful to study patients with DIC and g/b ratio could be regarded as a helpful indication of therapeutic effects.

Disseminated Intravascular Coagulation↗
PubMed1992

Use of fibrin glue to minimize bleeding of microvascular repairs in hypertensive rats.

The purpose of this study is to describe our technique of applying fibrin glue at the microvascular anastomotic site and to evaluate the effect of fibrin glue on anastomotic hemostasis and patency under various high pressure states using dopamine-induced acute hypertension in rats. A total of 72 male Wistar Kyoto rats, 10 weeks old, were used in this study. Under urethane anesthesia, end-to-end anastomosis of the left femoral artery was performed using 10-0 nylon suture by the standard interrupted suture technique. Pasteurized fibrin glue was then topically applied upon the suture line of the anastomosis. Thirty-six normotensive rats were divided into three groups based on the number of sutures (4, 6, or 8) used to complete the anastomosis. Groups were subdivided, half receiving fibrin glue application and half without. Thirty-six dopamine-induced acutely hypertensive rats were divided into three groups based on the blood pressure levels of 150, 200, and 250 mmHg, respectively. These groups were again subdivided, with half receiving glue applications. Microvascular anastomosis was performed using 6 nylon sutures. Patency rates and anastomotic bleeding were evaluated. The results revealed that successful anastomoses could be performed with fewer sutures when fibrin glue was used as a reinforcement at the anastomosis. Fibrin glue was also effective at the maximum blood pressure (250 mmHg) with no anastomotic leakage and no decrease in postoperative patency rate. These results suggest that conventional microsurgical suturing technique combined with fibrin glue would be effective in the prevention of leakage in microsurgical repairs, even under conditions of high blood pressure.

Anastomosis, Surgical↗
PubMed1992

[Evaluation of novel assays for the detection of crosslinked fibrin degradation products in whole blood by the agglutination of the red blood cells].

We evaluated the clinical significance of two novel assays for the detection of crosslinked fibrin degradation products (XDP) in whole blood using the agglutination of the red blood cells (SimpliRED D dimer and SimpliRED D dimer-500, AGEN, Australia). XDP made serially by plasmin in vitro, were detected by the SimpliRED D dimer assay, but fibrinogen degradation products showed weak reactivity. Ten of the fifty four clinical samples collected with EDTA-2K, changed to positive on these assays after overnight incubation at 4 degrees C. Anemia and hemolytic samples had no effect on the assay results. The results obtained by the SimpliRED D dimer were negative for the normal subjects (n = 50) without exception. In our study, 81% and 95% of the patients, who showed abnormal levels of XDP in plasma and E fragments in serum respectively, were positive on the SimpliRED D dimer assay. The assay was as sensitive as the Rapidia-D dimer assay. In conclusion, the SimpliRED D dimer assay was clinically useful as a screening assay for the diagnosis of hypercoagulable and fibrinolytic states, since it could be performed simply and quickly.

Adult↗
PubMed1991

The observation of endothelial cells in vein grafts by the en face silver staining method.

The introduction of en face silver staining to microsurgery has provided useful, detailed information about endothelial cells with regard to their size, shape, and number. With this staining method, endothelial cells of rat vein grafts have been morphologically investigated following division of the site of observation into three areas: the recipient artery, the proximal part of the vein graft, and the midportion of the vein graft. The results show that the arterial endothelial cells are small and spindle-shaped, whereas the cells in the proximal vein graft location are larger. Finally, large, rounded endothelial cells are seen in the midportion of the graft. These results are quantitated through a computerized graphic analysis system, which provides estimations of the cell size, Feret's diameters, and irregularities in the cell borders. The combination of en face silver staining and computerized graphic analysis has been especially useful for comparing minute changes that occur in recovering/regenerating endothelial cells.

Animals↗
PubMed1991

[Differentiation between fibrin degradation products and fibrinogen degradation products by using newly developed ELISAs].

We should distinguish fibrin degradation products (FbDP) from fibrinogen degradation products (FgDP) in order to analyze fibrinolysis in vivo. We analyzed some disorders associated with hyperfibrinolytic states using ELISA for FbDP, FgDP and total fibrin (ogen) degradation products (TDP) (ORGANON TEKNIKA). Each ELISA was useful in terms of reproducibility and dilution linearity of plasma samples. There was no cross-reaction between FbDP and FgDP. The FgDP/FbDP ratio in normal individuals was 1.65. In patients with DIC, it was 0.43, with FgDP level being increased. These results suggest that fibrinolysis is enhanced in patients with DIC, but it is accompanied by fibrinogenolysis. On the other hand, the FgDP/FbDP ratio in patients given urokinase (UK) was 2.88. This suggests that fibrinogenolysis is enhanced in them. In our study, the FgDP/FbDP ratio increased as DIC improved. Thus, we can regard this as an index of therapeutic effects in patients with DIC. We conclude that these three ELISA are useful in analyzing disorders associated with hyperfibrinolytic states.

Disseminated Intravascular Coagulation↗
PubMed1990

Wound healing at the site of microvascular anastomosis: fibrin-stabilizing factor XIII administration and its effects.

Factor XIII has recently been recognized to play an important role as a fibrin-stabilizing factor to accelerate the wound healing process. We made an attempt to analyze the effect of how Factor XIII affects the results of the healing process at the site of a microvascular anastomosis. The strong fibrin stabilizing property of plasma Factor XIII maintained its high activity when administered intravenously and was effective for wound healing in a low-activity state made by subcutaneous administration of carbon tetrachloride. The enhanced network formation of the Factor-XIII-injected group was indicated by the accelerated maturation of the fibrin structure at the anastomotic site, exhibited both qualitatively and quantitatively. Stimulation and acceleration by Factor XIII of the healing process at the site of microvascular anastomosis were observed. It is therefore suggested that clinical use of Factor XIII may enhance the microvascular repair process. Details of the analysis using scanning electron microscopy (SEM) and a computerized graphic analyzer system (CGAS) are reported.

Anastomosis, Surgical↗
PubMed1988

Re-endothelialization stages at the microvascular anastomosis.

After microsurgical suturing, the wound healing process at the rat femoral artery anastomosis was studied with scanning electron microscopy. The re-endothelialization was divided into four successive stages, based on the development of a fibrin network and the rate of endothelial regrowth. Within 5 minutes of blood flow re-establishment the fibrin network formation started to cover the wound surface; it was completed by the 3rd or 4th day. The endothelial recovery started on the 2nd day and continued to the base of the suture by the 6th day. Re-endothelialization from the wound edge, which was formed between intact and injured endothelium toward the suture-restrained site, was a two-fold process: initially, a single endothelial film covered the anastomosis site, then, the singled endothelial sheet proliferated and thickened to complete the endothelialization. A better understanding of the stages involved in microvascular repair is beneficial in evaluating vascular recovery and its relationship to patency rates in microvascular surgery.

Animals↗