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Biomedical subjects

M Nasu

Publications and source records attributed to M Nasu.

449 records · Page 25Linked to original sources
PubMedDate not supplied

Long-term in vivo study of gas diffusion in bilaminar compliance chambers.

The problem of gas diffusion from compliance chambers in long-term pulsatile blood pump implantation continues. To evaluate and predict gas diffusion at the intrathoracic tissue interface, eight air-filled static bilaminar compliance chambers were implanted in four calves for a mean duration of 191 days. Mean volume loss was 40.3 +/- 6.2 ml (0.2 ml/day) compared with previous results of 1.2 ml/day for pure Hexsyn diaphragms. The residual gas in the chamber was analyzed as nitrogen = 89.6 +/- 0.6%; oxygen = 1.5 +/- 1.1%; and carbon dioxide = 8.8 +/- 0.6%. The resulting gas composition is assumed equivalent to that of the tissue interface and was used in developing a diffusion model. For a complete left ventricular assist system (LVAS), gas diffusion at the arterial blood and tissue interface was simulated. The predicted time to reach a minimum volume of 90 ml (compliance volume equal to full pump stroke volume) was in excess of 1 year.

Animals↗
PubMedDate not supplied

The in vitro effect of macrolides on the interaction of human polymorphonuclear leukocytes with Pseudomonas aeruginosa in biofilm.

The in vitro effect of macrolides at concentrations below the minimum inhibitory concentration (sub-MIC) on the interaction between Pseudomonas aeruginosa biofilm and human polymorphonuclear leukocytes (PMNs) was investigated by using a chemiluminescence assay. The PMN response to either mucoid or nonmucoid P. aeruginosa biofilm was strongly reduced compared with the response to planktonic bacteria (p < 0.01, p < 0.001, respectively). When biofilms were treated with erythromycin, clarithromycin, roxithromycin and azithromycin prior to incubation with PMNs, the chemiluminescence response was markedly enhanced as compared to untreated controls, and a dose-dependent effect was noted over the range of sub-MIC concentrations studied. In general, macrolides appeared to be slightly more active against mucoid biofilm. Azithromycin was shown to be the most active macrolide against P. aeruginosa biofilms. However, the treatment with sub-MICs of rokitamycin did not have any effect. On the other hand, treatment of planktonic bacteria with macrolides before being exposed to the PMNs did not affect the chemiluminescence response as compared to untreated controls. These findings suggest that macrolides inhibiting the biofilm formation of P. aeruginosa may facilitate the phagocytosis of bacteria by PMNs.

Anti-Bacterial Agents↗
PubMedDate not supplied

Bioactivity of the vascular endothelial growth factor trapped in fibrin clots: production of IL-6 and IL-8 in monocytes by fibrin clots.

The blood coagulation cascade is activated following vascular-wall injury. The serine protease thrombin is the final protease in this cascade that causes the formation of fibrin from fibrinogen. Thrombin also causes the activation of platelets, which are trapped in a fibrin net followed by hemostasis. Platelets gathered into fibrin clots release several growth factors such as platelet-derived growth factor and transforming growth factor beta. In the present study, we demonstrated that the vascular endothelial growth factor (VEGF) could be bound to fibrin clots in the plasma, and that incubation of the endothelial cells with these VEGF-bound fibrin clots induced proliferation of endothelial cells. Thus, it suggests that clot-bound VEGF may play a role in wound healing through the proliferation of endothelial cells and vascular smooth-muscle cells. On the other hand, a noticeable migration of monocytes was observed when they were cultured on dishes in the presence of VEGF-bound fibrin clots. Moreover, peripheral blood monocytes incubated in the presence of VEGF-bound fibrin clots strikingly increased the production of IL-6 and IL-8, demonstrating that VEGF trapped in fibrin clots not only induces proliferation of human umbilical vein endothelial cells and migration of monocytes but also enhances secretion of IL-6 and IL-8. Thus, our data suggest that fibrin clots that contain several growth factors act as a bioactive reservoir and may play an important role in hemostasis as well as wound healing.

Blood Coagulation↗
PubMedDate not supplied

The administration regimen of isepamicin in patients with chronic respiratory tract infection.

A total of 34 patients with intractable chronic respiratory tract infections were treated with isepamicin and/or piperacillin in different dosage regimens. A comparison of the bacteriological effect using a cross over method showed a reduction in the count of Pseudomonas aeruginosa in sputum in the group receiving once-a-day isepamicin combined with piperacillin, compared with the twice-a-day combined administration. A comparison of the clinical and bacteriological efficacy between the different regimen groups revealed no noticeable difference. The clinical effect of this regimen is comparable to the conventional regimen, but has the advantages of a safer dosage and ease of administration.

Adult↗
PubMedDate not supplied

The influence of azithromycin on the biofilm formation of Pseudomonas aeruginosa in vitro.

The influence of azithromycin on biofilm formation by Pseudomonas aeruginosa, a cause of refractory chronic respiratory tract infection, was investigated. Alginic acid produced by a mucoid strain of P. aeruginosa was quantified by high-performance liquid chromatography from colonies growing on an agar medium. Polysaccharides in the biofilm formed on silicon chips by a nonmucoid strain were determined by a tryptophan reaction. The effect of azithromycin was examined at concentrations below the minimum inhibitory concentration (sub-MIC) for each strain. Azithromycin significantly inhibited the production of alginic acid from the mucoid strain at > or = 1/256 MIC, and the production of exopolysaccharides from the nonmucoid strain at > or = 1/16 MIC. The inhibition of biofilm formation by azithromycin was also observed by scanning electron microscopy. These findings suggest that azithromycin inhibits biofilm formation by P. aeruginosa at concentrations well below the MIC.

Alginates↗
PubMedDate not supplied

Successful coronary angioplasty for the remaining coronary artery with two completely occluded arteries with prior bypass grafting.

A 61-year-old man underwent coronary artery bypass grafting because of severe three-vessel disease. Since he had post-operative anginal attacks, coronary angiography was performed. The examination revealed the right coronary artery (RCA) and left circumflex artery (LCX) to be completely occluded, and the left anterior descending artery (LAD) showed 90% stenosis. Furthermore, the three bypass grafts (to RCA, LCX and LAD) were all occluded. The patient had severe anginal episodes despite drug therapy. Since the patient refused a second bypass operation, we performed percutaneous transluminal coronary angioplasty on the LAD. Subsequently, the stenosis of LAD was reduced to 25%, eliminating subjective episodes of angina pectoris.

Angioplasty, Balloon↗
PubMedDate not supplied

Three cases of bronchial asthma after middle ages associated with pets.

Three cases of bronchial asthma after middle ages associated with pets were presented. Case 1 was a 39-year-old man who was admitted due to exacerbation of asthma after having fed a cat and a dog for 2 years. IgE-RAST was positive for cat fur and house dust. Inhalation test of cat hair antigen was positive. His symptoms improved by avoidance of the cat. Case 2 was 54-year-old woman suffering from asthma for 6 years after having fed a cat. IgE-RAST was positive for dog hair and cat fur. Symptoms did not improve by any treatment because she could not give up pets. Case 3 was a 45-year-old woman suffering from asthma attacks for two months. She had kept a dog for 1 year. IgE-RAST was positive for dog hair. Her symptoms disappeared by avoidance of the dog. Patients with pet allergy have increased in recent years because of the pet boom, but it is not so common to have asthma attacks in aged people. Bronchial asthma caused by allergens of pets easily improves by avoidance of them and it is important to establish early diagnosis of this disorder.

Adult↗
PubMedDate not supplied

Immunophenotyping of lymphocytes in the lung interstitium and expression of osteopontin and interleukin-2 mRNAs in two different murine models of pulmonary fibrosis.

In the surfactant protein C/tumor necrosis factor (SP-C/TNF) transgenic mouse, the TNF-alpha transgene is overexpressed in type II pneumocytes. Pulmonary lymphocytic infiltration develops which is followed by fibrotic changes including accumulation of fibroblasts and deposition of extracellular matrix. We hypothesized that lymphocytes played a role in the development of pulmonary fibrosis in this model. Lymphocytes were recovered from the interstitium of the lung and analyzed by flow cytometry. The absolute number of lymphocytes recovered from transgenic mice were approximately four times of that in littermates. Flow cytometric analysis showed the presence of gamma delta T cells and B1 cells in the former group but these cells were almost absent in the lung of non-transgenic littermates. We also studied lymphocytes accumulating in the lung during bleomycin (BLM)-induced pneumopathy. Serial analyses showed a progressive increase of CD4/CD8 ratio after injection of BLM, reaching a peak at day 14, then decreased to the normal level by day 48. Northern blot analysis of the lung showed an enhanced expression of interleukin (IL)-2 and osteopontin (OPN) mRNA in those two models of pulmonary fibrosis. Expansion of clonal alpha beta T cells as detected by reverse transcriptase-polymerase chain reaction/single strand conformation polymorphism (RT-PCR/SSCP) suggests involvement of antigen-driven mechanisms in the development of pulmonary fibrosis.

Animals↗
PubMedDate not supplied

Evaluation of several saccharides as osmotic agent for peritoneal dialysate.

OBJECTIVE: The carbonyl group of glucose reacts non-enzymatically with the amino group of protein to form advanced glycosylation end-products (AGEs). AGEs are found in the peritoneum of continuous ambulatory peritoneal dialysis patients, and this AGE formation is suspected to be one of the causes of impaired peritoneal function. In order to control AGE formation in the peritoneum, AGE formation and ultrafiltration in rats were examined with peritoneal dialysates using as osmotic agents saccharides that lack a carbonyl group, the saccharic acid lactobionate [molecular weight (MW) 358.30], the sugar alcohol maltitol (MW 344.32), and the nonreducing sugar nistose (MW 666.58). DESIGN: Bovine serum albumin (BSA) (25 mg/mL) was incubated with 18, 36, and 72 mg/mL maltitol, lactobionate, nistose, and glucose at 37 degrees C. After 3 or 6 weeks, amounts of furosine and N-(carboxymethyl) lysine were measured. A 20-mL intraperitoneal injection of a lactate-based dialysate (osmotic pressure 388 mOsm/kg) containing 4.34% maltitol, 4.52% lactobionate, or 8.4% nistose was given to Sprague-Dawley rats and, after 2, 4, or 6 hours, the quantity of effluent and levels of urea nitrogen and creatinine in the effluent and in serum were measured. RESULTS: No increases in furosine or N-(carboxymethyl) lysine were seen with maltitol, lactobionate, or nistose after 3 and 6 weeks of incubation with BSA; AGE formation was not observed. In the study in rats, the quantity of abdominal fluid after a 6-hour dwell was nistose > lactobionate > maltitol > glucose. No differences in dialysate-to-plasma ratios for urea nitrogen or creatinine were seen in any group. CONCLUSIONS: AGE formation in peritoneal tissue might be controlled by using saccharides with a modified carbonyl group as osmotic agents for peritoneal dialysates. Nistose is considered to yield the most efficient dialysis.

Animals↗
PubMedDate not supplied

Recovery of end-stage organ dysfunction by circulatory assist.

To clarify the effectiveness of left ventricular assist on recovery of critical organ dysfunction, 18 patients with ventricular septal rupture or free wall rupture after acute myocardial infarction were retrospectively studied. Fifteen patients were managed with an intraaortic balloon pump (IABP group), and three with a left ventricular assist device (LVAD group) after surgery. In the IABP group, nine patients survived and six died. There were no significant differences between survivors and nonsurvivors with respect to age, cardiopulmonary bypass time, or preoperative renal function. In addition, there were no significant differences in the early postoperative changes in cardiac index. Larger doses of catecholamines were required in nonsurvivors than in survivors, however; blood urea nitrogen and creatinine levels were significantly higher in nonsurvivors than in survivors, and the nonsurvivors' creatinine clearance values stayed under 20 ml/min during the postoperative course, so that all nonsurvivors required renal assist. All in the LVAD group were weaned. Two patients were lost, however, because of cardiac arrythmia and massive gas embolism. Cardiac index in the LVAD was maintained at over 2.1 L/min/m2 with a minimum dose of catecholamines, regardless of poor left ventricular function, and creatinine clearance recovered to over 20 ml/min during circulatory assist. From these data, high doses of catecholamines depressed renal function after surgery. Therefore, it has been concluded that the major role of circulatory assist is to maintain more of the physiologic circulation with minimum doses of drugs.

Aged↗
PubMedDate not supplied

Long-term echocardiographic follow-up of patients with a tricuspid bioprosthesis.

To clarify the long-term results of bioprosthetic valve function in the tricuspid position, 29 consecutive patients who underwent tricuspid valve replacement (TVR) were evaluated. There were 20 girls/women and 9 boys/men, with ages ranging from 6 to 61 years (mean 41.4 years). The bioprosthetic valves included Hancock in 2, and Carpentier-Edwards in 27. The follow-up period ranged from 32 to 145 months (mean 89 months). Regurgitant flow of the tricuspid bioprosthesis was studied by color Doppler echocardiography. Peak velocity (Vp) and pressure half time (PHT) were measured by continuous wave Doppler echocardiography. Operative mortality was 13.7% (4/29), with the actuarial survival rate, including operative deaths, 75% at 10 years. Valve thrombosis developed in one patient 4 years after TVR. Color Doppler showed regurgitation in 7 of the 20 patients who were completely followed up, but they were all asymptomatic and required no special intervention. Cusp tear or calcification requiring reoperation was not observed in this study, including 8 patients younger than 35 years of age. The Vp was significantly slower, and PHT was significantly prolonged, in the tricuspid rather than the mitral position. These data demonstrate that bioprosthetic valves in the tricuspid position can be used safely. Doppler examination should be performed taking these different flow dynamics into account.

Adolescent↗