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Biomedical subjects

K Kanda

Publications and source records attributed to K Kanda.

268 records · Page 15Linked to original sources
PubMedDate not supplied

Mating in Bacillus thuringiensis can induce plasmid integrative prophage J7W-1.

Bacillus thuringiensis serovar israelensis, a bacterium which possesses plasmid transfer ability after mating, has been lysogenized by plasmid integrative phage J7W-1. The induction of phage in this J7W-1 lysogen was observed after mating with phage-insensitive strains, such as B. thuringiensis serovar thuringiensis, B. cereus and B. subtilis, as well as the phage-sensitive strain serovar israelensis. The phage induction was not observed after mating with B. thuringiensis strains AF101, serovar dendrolimus and serovar indiana. Because these strains are naturally associated with J7W-1 or its related phage, the data strongly suggest a constitutive expression of the repressor encoded by the prophage in these strains. However, the phage induction was observed in B. thuringiensis serovar aizawai, although it contained the J7W-1 DNA homologous region(s).

Bacillus Phages↗
PubMedDate not supplied

Cytologic evaluation of phyllodes tumors as compared to fibroadenomas of the breast.

In an attempt to better understand the cytopathologic features of phyllodes tumors (PTs) and to differentiate PTs from fibroadenomas (FAs) of the breast, cytologic smears prepared from 17 and 19 histologically diagnosed cases of PT and FA, respectively, were reviewed. PT cases were histopathologically graded as benign, borderline and malignant. Cytologically, hypercellularity of stromal cells with recognizable cytoplasm was observed in 6 of 7 borderline and malignant PT cases, but none of the benign PT or FA cases revealed such hypercellular stroma. Between all PT and FA cases, no statistically significant differences could be obtained in the nuclear size of stromal cells, folding of epithelial cell sheets or number of foamy macrophages. The study revealed that the abundance of stromal cells with cytoplasm, not naked nuclei, was strongly suggestive of borderline and malignant PT, but the differentiation between benign PT and FA was difficult on the basis of the cytopathologic findings.

Adolescent↗
PubMedDate not supplied

Phenotypic modulation of smooth muscle cells in intima-media incorporated hybrid vascular prostheses.

Hierarchical hybrid vascular grafts were constructed with an endothelial cell (EC) monolayer and hybrid medial layer composed of smooth muscle cells (SMCs) and type I collagen gel. The grafts, implanted into canine carotid arteries for up to 12 weeks, were ultrastructurally examined with a transmission electron microscope. Before implantation, SMCs incorporated into hybrid media were round and intracellularly filled with synthetic organelles such as rough endoplasmic reticula, mitochondria, free ribosomes, and Golgi complexes. Two weeks after implantation, bipolar spindle shaped SMCs still remained in a synthetic phenotype. At 12 weeks, circumferentially aligned SMCs were abundant in contractile apparatus such as myofilaments, dense bodies, and basement membranes. In a morphometric evaluation, the populations of three phenotypic SMCs (synthetic, intermediate, and contractile SMCs) were quantified. At 2 weeks, the proportions were 50.5, 41.8, and 7.7% for synthetic, intermediate, and contractile phenotypes, respectively. At 12 weeks, they were 9.9, 26.2, and 63.8%. These findings indicated that SMCs incorporated into hybrid grafts were transformed from a synthetic to a contractile phenotype under pulsatile stressed conditions after 12 weeks in vivo. Thus, the intima/media incorporated hybrid graft reconstructed a vessel wall similar to a native one in terms of structure and function.

Animals↗
PubMedDate not supplied

In vitro reconstruction of hybrid vascular tissue. Hierarchic and oriented cell layers.

Hybrid vascular tissue was hierarchically reconstructed in vitro. A hybrid medial layer composed of type I collagen gel, in which SMCs derived from a mongrel dog were embedded, was formed on the inner surface of a compliant porous polyurethane graft (internal diameter = 3 mm). Endothelial cells (ECs) from the same animal were seeded and cultured on the hybrid media to build an intimal layer. Subsequently, hierarchically structured grafts constructed in this manner were subjected to pulsatile flow (flow rate: 8.5 ml/min; frequency: 60 rpm; amplitude: 5% of graft outer diameter) of culture medium (Medium 199 supplemented with 20% fetal calf serum). After stress loading for as long as 10 days, tissues were morphologically investigated with a light microscope and a scanning electron microscope. Inner surfaces of the hybrid tissues were covered with EC monolayers that aligned along the direction of the flow (i.e., longitudinally). However, SMCs beneath the intima aligned in the circumferential direction. These cellular orientations resembled those in native muscular arteries. The pulsatile stress loaded hybrid tissue mimicked native muscular arteries with respect to hierarchic structure and cellular orientation. In vitro mechanical stress loading on a hybrid graft might provide a high degree of integrity in terms of tissue structure that promises high tolerance toward hydrodynamic stress and regulation of vasomotor tone upon implantation.

Animals↗
PubMedDate not supplied

Mechanical stress induced cellular orientation and phenotypic modulation of 3-D cultured smooth muscle cells.

The effect of periodic stretch on cellular orientation and intracellular ultrastructure of three-dimensionally (3-D) cultured arterial smooth muscle cells (SMCs) was investigated. Ring shaped hybrid tissues were prepared by thermal gelation of a mixed solution of Type I collagen and SMCs derived from bovine aorta. The gels were subjected to three modes of stress loading: floated (control), stretched isometrically (static stress), and periodically stretched and recoiled with 10% amplitude at 60 rpm frequency (dynamic stress). After 4 weeks of stress loading, the gels were morphologically investigated with a light microscope and a transmission electron microscope (TEM). Irrespective of static or dynamic stress loading, SMCs in stress loaded gels exhibited an elongated bipolar spindle shape and were oriented parallel to the direction of stretch, whereas those in control gels were polygonal shaped and randomly oriented. TEM observation showed that SMCs in control and static stress loaded gels were intracellularly filled with organelles, such as rough endoplasmic reticulum, free ribosomes, Golgi complexes, and mitochondria, indicating that the cells were of the synthetic phenotype. On the other hand, SMCs in dynamic stress loaded gels tended to have increased contractile apparatus, such as myofilaments, dense bodies, and basement membranes, suggesting that periodic stretch plays an important role in phenotypic modulation of SMCs from the synthetic to the contractile state, as well as cellular orientation.

Animals↗
PubMedDate not supplied

Small diameter vascular prostheses with incorporated bioabsorbable matrices. A preliminary study.

The authors have designed small diameter vascular prostheses with incorporated matrices that can be absorbed into a growing anastomotic neointima. First, a gelatin-heparin complex was coated on the inner surface of tubular ultrafine polyester fabrics presealed with heat denatured albumin. Second, to control the bioabsorption rate, the prepared grafts were cross-linked with polyepoxy compounds for 3 days (Group I; n = 14) or 5 days (Group II; n = 4). These grafts, 3 mm in diameter and 4 cm long, replaced the carotid arteries of nine mongrel dogs weighing 9.5-14 kg. Six of eight (75%) grafts in Group I were patent when the animals were killed 4 weeks after surgery. Doppler sound examination revealed that the remaining six were patent for 16 weeks. In Group II, three of four (75%) grafts were patent when the animals were killed 8 weeks after surgery. In both groups, scanning electron microscopic study showed neither platelet aggregation nor fibrin formation on the midportion. However, these two groups significantly differed in histology. In Group I, thin anastomotic neointima advanced over the mostly absorbed gelatin-heparin complex layer. Connective tissue was well formed around the polyester scaffold. In contrast, thick neointima advanced over the gelatin-heparin complex layer that still remained on the luminal surface in Group II. These results suggest that the gelatin-heparin complex, when cross-linked adequately, could simultaneously function as a temporary antithrombogenic surface and as an excellent substructure of an anastomotic neointima.

Anastomosis, Surgical↗
PubMedDate not supplied

Experimental study of extraaortic balloon counterpulsation as a bridge to other mechanical assists.

A special extraaortic balloon was developed that can be placed around the ascending aorta. This balloon can easily support the heart temporarily in a median sternotomy field, especially in cases in which it is difficult to use intraaortic balloon pumping because of peripheral arterial disease. The goal of this study was to judge the applicability of this extraaortic balloon counterpulsation. An extraaortic balloon was placed around the ascending aorta of eight adult canines. Two heart failure models were used in this study: group A-moderate heart failure; group B-severe heart failure. In group A, the aortic systolic pressure was significantly reduced (9.3%, p < 0.01), but in group B, there was no significant change. In group A, there was a significant increase in cardiac output (12.0%, p < 0.01), but in group B, there was no significant change. The endocardial viability ratio in both groups significantly increased (group A: 11.3%, p < 0.01; group B: 11.9%, p < 0.05). An extraaortic balloon around the ascending aorta is easily applicable through a median sternotomy, and can be used as a bridge to more powerful mechanical assists when intraaortic balloon pumping cannot be used.

Animals↗
PubMedDate not supplied

Human melanoma treated by boron neutron capture therapy: comparison of the clinical response with the predicted response.

PURPOSE: A patient with malignant melanoma on the left foot was treated by thermal neutron capture therapy using 10B-paraboronophenylalanine. We compared the actual (clinical) response with the predicted response estimated using our past experimental and clinical data, and discussed some problems to be overcome in the future. MATERIALS AND METHODS: We adopted an intravenous drip infusion of the compound whereby 170 mg/kg of the drug was administered over 4-5 hours before neutron irradiation. The patient was then irradiated with thermal neutrons from the Musashi Reactor at a reactor power of 100 kW and a neutron flux of 1.0 x 10(9) n/cm2/s at the collimator surface. The total absorbed dose to the melanoma and the surrounding skin was calculated by multiplying the thermal neutron fluences by the conversion factor. RESULTS: The total absorbed doses to the melanoma and the surrounding normal skin were calculated as 19.0 and 9.4 Gy, respectively. These absorbed doses were estimated at 33.5 and 14.2 RBE-Gy, respectively, assuming that the relative biological effectiveness (RBE) of the high LET radiations was 2.0 and that each component of the mixed radiation was simply additive. The melanoma showed marked regression with mild skin reaction (dry desquamation) a month after therapy, and finally disappeared 10 months after therapy. There were no no substantial side effects. CONCLUSION: We concluded that the outcome of our calculated dose values agreed well with the clinical response and that their compatibility indicated considerable validity for our approach. However, there are still some problems-uncertainty concerning the 10B concentration in tumor and skin, determination of the total absorbed dose, and a single curative dose for malignant melanoma-to be overcome with regard to clinical use of this therapy.

Aged↗
PubMedDate not supplied

Experimental study of combination of extraaortic balloon counterpulsation and ventricular assist cup to acute heart failure in dogs.

The goal of this study is to evaluate the applicability and effectiveness of combination support of the extraaortic balloon (EAB) and the ventricular assist cup (VAC) to the acute heart failure model. Under general anesthesia, 10 adult dogs were used. Through the median sternotomy, EAB was placed around the ascending aorta and VAC in the pericardial cavity. After heart failure was induced by administration of propranolol, the on-off tests of devices were done as follows. Only EAB was used, and only VAC was used and both devices were used. Regional blood flows (RBFs) of both ventricles, liver kidneys, and brain were measured by colored microsphere technique. Hemodynamic parameters were also measured. In heart failure model, cardiac output (CO) decreased to 66% of control value. In the group assisted by EAB, aortic peak-diastolic pressure and RBFs of both ventricle and brain increased significantly. In the group assisted by VAC, CO and RBFs of all but the left ventricle significantly increased. In the group assisted by EAB and VAC, aortic peak-diastolic pressure, CO, and all five RBFs significantly increased. These results suggest the combination of EAB and VAC is applicable and effective and would be a promising implantable device for the chronic heart failure.

Acute Disease↗
PubMedDate not supplied

A new double lumen balloon catheter for retrograde cerebral perfusion via jugular vein cannulation.

A new catheter for retrograde cerebral perfusion (RCP) was developed that can be used to deliver blood directly into the internal jugular vein (IJV) beyond the venous valves at the jugular-subclavian junction and prevent blood from draining into the lower half of the body. This catheter can be inserted into the IJV via a standard puncture technique by use of a 14 Fr sheath. The catheter shaft has two channels for balloon inflation and blood perfusion, respectively. A balloon for occlusion of drainage veins (superior vena cava and azygos vein) is installed at the catheter tip. Side holes, through which oxygenated cold blood is delivered into the IJV, are located 95 mm from the catheter tip. In a mock circulatory study, the pressure at the perfusion line (16-118 mmHg) increased with the increasing flow rate (0-400 ml/min). In clinical application, under circulatory arrest with profound hypothermia, inflation of the balloon effectively reduced blood drainage into the lower half of the body and, consequently, RCP was successfully performed (flow rate, 300-350 ml/min; pressure at the IJV, 15 mmHg). Because all of these procedures were controlled from outside the operative field, RCP by use of this catheter could be useful in distal arch replacement via left lateral thoracotomy.

Animals↗