Is there a possibility for a glutaraldehyde-free porcine heart valve to grow?

OBJECTIVE: A challenging issue is to create a heart valve with growth and remodeling potential, which would be of great interest for congenital heart valve surgery. This study was performed to evaluate the growth and remodeling potentials of a decellularized heart valve. METHODS: In 4 juvenile sheep (age 12 +/- 1 weeks) with a weight of 24.3 +/- 4.4 kg, a 17-mm diameter decellularized porcine valve was implanted as pulmonary valve replacement. Valve growth was evaluated by transthoracic echocardiography. At explantation, valves were evaluated by gross examination, light microscopy (hematoxylin and eosin, von Kossa, Sirius red, Weigert and Gomori staining), electron microscopy and immunohistochemistry. Atomic absorption spectrometry was performed to evaluate calcium content. RESULTS: All animals showed fast recovery. The mean follow-up was 9.0 +/- 1.8 months. All sheep at least doubled their weight (54.3 +/- 9.2 kg). Echocardiography showed no regurgitation and a flow velocity of 0.7 +/- 0.1 m/s at the latest follow-up. The valve diameter increased from 17.6 +/- 0.5 to 27.5 +/- 2.1 mm (p < 0.018). Gross examination showed a similar wall thickness of the implanted valve and native pulmonary wall, with smooth and pliable leaflets. Histology showed a monolayer of endothelial cells, fibroblast ingrowth and production of new collagen. No calcification was seen at von Kossa staining, confirmed by low calcium content levels of the valve wall and leaflets at atomic absorption spectrometry. CONCLUSIONS: This glutaraldehyde-free heart valve showed not only the absence of calcification, but also remodeling and growth potential.

Results of a decellularized porcine heart valve implanted into the juvenile sheep model.

OBJECTIVE: This study was performed to evaluate the possibility of creating a glutaraldehyde-free porcine xenograft to improve long-term durability. METHODS: A decellularized porcine pulmonary valve was implanted into the right ventricular outflow tract of 7 juvenile sheep. Valves were explanted after 3 months (n = 4) and 6 months (n = 3). Evaluation was performed by gross examination, radiography, histology (hematoxylin-eosin and Sirius red staining), and immunohistochemistry. Quantitative determination of calcium content was investigated by atomic absorption spectrometry. RESULTS: All animals showed fast recovery without complications. At explantation, all decellularized valves showed smooth and pliable leaflets without evidence of thrombosis. The valve wall was also smooth and pliable without hardness. Light microscopy showed a monolayer of host endothelial cells covering the inner surface of the heart valves and repopulation of host fibroblasts into the deeper layers. Sirius red staining enabled visualization of the production of new collagen. Radiographic results showed an absence of calcification, confirmed by the low calcium levels (1.08 +/- 0.28 microg/g and 0.73 +/- 0.31 microg/g at 3 and 6 months, respectively) revealed by atomic absorption spectrometry. CONCLUSIONS: The results with the juvenile sheep model showed that decellularized heart valves are recellularized in vivo. Host endothelial cells form a monolayer on the inner surface of the valve matrix. Furthermore, host fibroblasts repopulate the valve matrix and produce collagen; thus, a remodeling potential can be expected.

Seasonal blood pressure and body weight variation in patients on chronic hemodialysis.

AIM: The relation of ambient temperature (AMT) and relative humidity to systolic blood pressure (SBP), diastolic blood pressure (DBP), body weight (BW), and body weight gain between dialysis sessions (DeltaBW) was examined in hemodialysis patients by Fourier analysis. METHODS AND RESULTS: The authors recruited 144 dialysis patients from a hemodialysis center in Okinawa, Japan where there is distinct seasonal variation in monthly AMT but a constant intradiurnal temperature change throughout the year. All patients had been undergoing chronic and regular hemodialysis three times per week. SBP, DBP, and BW before dialysis sessions and DeltaBW were recorded in 1994. Mean monthly Okinawa AMT in 1994 was highest in August and lowest in February and March, and the mean monthly relative humidity in 1994 was highest in June and lowest in January. Mean SBP and DBP were lowest in August and June respectively, and greatest in December. BW was lowest in July and September, and greatest in February and March; DeltaBW was lowest in July and greatest in January. These seasonal patterns were well reproduced by the first Fourier component. The cross-correlation coefficient showed that monthly mean AMT and SBP, DBP, BW, and DeltaBW were correlated with a lag time of 5 or 6 months. The cross correlation coefficient showed that relative humidity and SBP, DBP and DeltaBW were also correlated with a 6-month lag time. In analyzing subgroups of patients according to the presence or absence of antihypertensive medications, a seasonal change was observed in the SBP and DBP of patients not being treated with antihypertensives, and in the DBP of patients taking antihypertensive medications, but not in the SBP of patients taking antihypertensive medications. CONCLUSION: Seasonal variations in SBP, DBP, BW and DeltaBW were evident. AMT and the relative humidity correlated strongly with SBP, DBP, BW and DeltaBW. The clinical implications of these findings in hemodialysis patients warrant further investigation.

Serum C-reactive protein (CRP) and risk of death in chronic dialysis patients.

BACKGROUND: The prognosis of chronic dialysis patients is poor, in part due to the high incidence of cardiovascular disease. Malnutrition, such as hypoalbuminaemia, has been shown to be a predictor of death in this group of patients, while serum C-reactive protein (CRP) is a predictor of myocardial infarction and sudden death. Thus, the aim of the present study was to determine of the relationship between CRP and serum albumin concentration, and the value of baseline CRP data in the prediction of death. METHODS: In one of the dialysis units in Okinawa, Japan, baseline CRP data was available (n=163, 95 men and 68 women) in January 1991. These patients were divided into two groups according to their baseline CRP levels, with group 1 consisting of CRP<10 mg/l (n=128) and group 2 of CRP> or =10 mg/l (n=35), and then followed up until the end of 1997. Survival curves were calculated using the Kaplan-Meier method. The statistical significance of the relationship between CRP levels and the risk of death was evaluated by multiple logistic analysis with covariables such as age, sex, diabetes mellitus, serum albumin, and blood pressure. RESULTS: The mean (SD) level of serum albumin was 38 (3) g/l in group 1 and 36 (3) g/l in group 2 (P<0.00001). The 5-year survival rate was significantly poorer in group 2 (44.4%) than in group 1 (82.5%) (P<0.0001). Furthermore, the risk of death was significantly higher in group 2 (relative risk 3.48 (95% confidence interval 1.76-6.89), P<0.0003) by multivariate Cox proportional hazard analysis. CONCLUSIONS: CRP is a significant predictor of death in chronic dialysis patients, independent of serum albumin and other possible confounders. Dialysis patients with high CRP levels should be carefully evaluated and monitored regardless of serum albumin concentrations in the normal range.

Blood pressure variability as an adverse prognostic risk factor in end-stage renal disease.

BACKGROUND: Prospective and case-control studies show that blood-pressure variability is an independent risk factor for severe organ damage and cardiovascular events in hypertensives. We prospectively studied the association between systolic blood pressure variability and cardiovascular mortality and mortality from all causes in end-stage renal disease patients. METHODS AND RESULTS: The subjects were 144 patients (86 men, 58 women; mean age+/-SD, 52+/-13 years) who underwent dialysis in the same dialysis centre and were examined for blood-pressure variability. The study period was 38 months beginning in January 1995, during which six cardiovascular and seven noncardiovascular fatalities occurred. Coefficient of variation in systolic blood pressure in 1994, as an indicator of systolic blood pressure variability, ranged from 7.8 to 14.6%. Cumulative incidence of death from all causes was related to coefficient of variation in systolic blood pressure. The difference between the maximum and minimum systolic blood pressure (deltaSBP) in 1994 ranged from 44 to 146 mmHg (mean+/-SD, 78+/-13 mmHg) and correlated significantly with coefficient of variation in systolic blood pressure (r = 0.65, P<0.0001). Cox regression analysis was used to identify the independent predictors for mortality. The hazard ratio for death from all causes increased 1.63 times per 1% increase in coefficient of variation in systolic blood pressure (hazard ratio; 95% confidence interval: 1.63; 1.05-2.53) and 1.03 times per 1 mmHg increase in deltaSBP (1.08; 1.03-1.14). CONCLUSION: These results suggest that systolic blood pressure variability may be a significant prognostic factor in end-stage renal disease.

Low diastolic blood pressure, hypoalbuminemia, and risk of death in a cohort of chronic hemodialysis patients.

In a previous report, we showed that nutritional status and especially serum albumin had great predictive value for death in chronic hemodialysis patients, whereas blood pressure did not. In the present study, we analyzed the causes of death in consideration of the relationship between serum albumin and blood pressure. A total of 1,243 Okinawan patients (719 males, 524 females) undergoing hemodialysis in January 1991 were followed up through the end of 1995. Three hundred forty-two of the patients died, 45 received transplants, and 12 were transferred by the end of the follow-up period. The total duration of observation was 5,110.3 patient-years. Blood pressure as well as clinical and laboratory variables were determined immediately prior to the first dialysis session in January 1991. The crude death rate was 40.0% when the diastolic blood pressure (DBP) <70 mm Hg, 35.0% at 70 to 79 mm Hg, 25.0% at 80 to 89 mm Hg, 25.0% at 90 to 99 mm Hg, and 13.0% at >100 mm Hg. The death rate showed an inverse correlation with DBP. DBP showed a significant positive correlation with serum albumin (r = 0.137, P < 0.001) and age (r = -0.325, P < 0.0001). The adjusted odds ratio (95% confidence interval) of death was 0.84 (0.71 to 0.99) with 10 mm Hg increments in DBP when the reference DBP was less than 69 mm Hg. Low DBP may be a manifestation of malnutrition and/or cardiovascular disease in chronic hemodialysis patients. Target DBP levels may be higher levels in chronic hemodialysis patients than the general population.

An epidemiologic analysis of parathyroidectomy in chronic dialysis patients. The Okinawa Dialysis Study Group.

Parathyroidectomy (PTX) is one of the treatments of choice for secondary hyperparathyroidism in chronic dialysis patients. Due to the large increase in long-term dialysis patients, hyperparathyroidism is becoming a common clinical problem. Several studies on PTX have reported various surgical procedures, but limited information is available on the incidence and risk factors of the surgery. The Okinawa Dialysis Study (OKIDS) registry is a community-based dialysis registry. It covers the entire area of Okinawa from when the use of chronic dialysis began in 1971. By the end of 1990, a total of 1,986 chronic dialysis patients were registered and 128 of these had undergone PTX by the end of 1993. The cumulative incidence of PTX was 4.3 in DM and 15.2 in non-DM per 1,000 patient-years. About half of the PTX patients underwent the surgery within 10 years of dialysis. By logistic analysis, the risk of PTX was seen to increase significantly with the duration of dialysis, P < 0.0001. Other clinical variables such as sex, age at the start of dialysis and the presence of diabetes mellitus were not significant predictors of PTX. The probability of PTX increased linearly with the duration of dialysis (r = 0.83, p < 0.0001). After the introduction of active vitamin D in 1981, the probability of PTX was significantly decreased (p < 0.05) compared to the pre-vitamin D period ('71-'80). With prolongation of the duration of dialysis, the risk of PTX increased steadily and was estimated to be 10 percent in 10 years and 20 percent in 20 years. Other uremic factors determining a pathological transformation of parathyroid tissue from reactive to autonomous growth remained to be investigated.

Alpha replacement method for the displaced Swan neck catheter.

We have developed a new method for the displacement of the Swan neck straight (SNS) catheter and have named it the "alpha replacement method." The procedure is to insert a 1.5 mm flexible metal guide wire into the transfer tube, passing it through the catheter tip until it touches the mesenterium. Continued gentle pressure will cause the guide wire to make a big loop in the abdomen, and as the loop increases in size, the catheter will move into the minor pelvic space. The guide wire is pulled out by pressing down on the lower abdomen, and the catheter remains in the minor pelvic space. The procedure is then complete. The alpha replacement method was successful in all 8 patients, with the manipulation time being about 15 minutes. No complications have occurred.

Surface antigens on HeLa cells persistently infected with HVJ (Sendai virus).

Surface antigens of HeLaHVJ cells, a cell line persistently infected with HVJ, were studied by fluorescent antibody staining. After absorption with concentrated HVJ virions and HeLa cells, anti-HeLaHVJ antiserum was able to demonstrate specific surface fluorescence on HeLaHVJ cells, while this serum no longer reacted with original HeLa cells nor with HVJ virions. During cytolytic infection of HeLa cells with HVJ, this specific surface antigen appeared at an early stage of infection prior to the appearance of newly synthesized HVJ viral antigens and moreover appeared in spite of the inhibition of viral protein synthesis. This antigen was detected neither on HeLa cells infected with other myxoviruses except HVJ nor on various other kinds of cells infected with HVJ. The specific surface antigen was still found on the HeLaHVJ cell surface after incubation at 38 degrees C for two days, while HVJ structural antigens on the cell surface no longer could be detected. Mild short-term treatment of HeLa cells with trypsin, neuraminidase from vibrio cholerae, phospholipase-C and hyaluronidase failed to expose specific antigen. The antigen was distinguishable from the Forssman and human blood type antigens. The mechanism of appearance of a new antigen on the surface of HeLaHVJ cells remains unclear.