Impact of biofeedback-induced cardiovascular stability on hemodialysis tolerance and efficiency

BACKGROUND

Hypotension is caused by a drop in blood volume during ultrafiltration, followed by vasoconstriction and reduced perfusion in some regions of the body.

METHODS

We carried out a prospective controlled crossover study on 12 hypotension-prone patients with two different modalities: (A) acetate-free hemodiafiltration with standard ultrafiltration control, and (B) acetate-free hemodiafiltration with monitoring of blood volume and automatic biofeedback with machine-driven adjustments on ultrafiltration and dialysate conductivity. We measured urea Kt/V and equilibrated Kt/V (eKt/V), urea rebound, and urea removal. Hypotensive episodes and interventions were recorded.

RESULTS

In group B, fewer hypotensive episodes were recorded (24 out of 72 in group B vs. 59 out of 72 in group A). Saline infusion was required in 57 cases in group A and 15 cases in group B. Urea Kt/V was 1.34 +/- 0.08 in group A and was 1.26 +/- 0.06 in group B; eKt/V was much higher in group B (1.12 +/- 0.05) than in group A (1.03 +/- 008). A significantly higher rebound was observed in group A (14.2 +/- 2.7%) compared with group B (6.4 +/- 2.3%). Discussion. A greater solute sequestration seems to occur during hemodialysis with hypotension. This results in lower eKt/V, enhanced postdialytic rebound, and lower solute removal. Higher efficiency can be observed when dialysis is carried out smoothly and cardiovascular stability is maintained. We conclude that new systems for blood volume monitoring and automatic biofeedback may not only reduce the number of hypotensive episodes during dialysis, but may also contribute to significantly increase the efficacy of the treatment.

Ribozyme-mediated down-regulation of ErbB-4 in estrogen receptor-positive breast cancer cells inhibits proliferation both in vitro and in vivo

ErbB-4 is a recently discovered member of the class I receptor tyrosine kinase family (ErbB). Little is known about its expression and its importance in human malignancy. To delineate the biological function of ErbB-4 receptors in breast cancer, we used a hammerhead ribozyme strategy to achieve down-regulation of ErbB-4 receptors in various breast cancer cell lines. We observed that down-regulation of ErbB-4 in estrogen receptor-positive (ER+) human breast cancer cell lines (MCF-7 and T47D), which express relatively high levels of ErbB-4, significantly inhibited colony formation. No effects were observed in estrogen receptor-negative (ER-) MDA-MB-453 cells, which express low levels of endogenous ErbB4 and high levels of ErbB-2 and ErbB-3. This occurred despite the fact that fluorescence-activated cell sorter analysis of these latter cells revealed that the expression of the ErbB-4 receptor was completely abrogated by ribozyme treatment. Furthermore, down-regulation of ErbB-4 in T47D and MCF-7 cells significantly inhibited tumor formation in athymic nude mice (P < 0.03 and P < 0.001, respectively). In addition, NRG-stimulated phosphorylation of ErbB-4- and NRG-induced colony formation was significantly reduced in ribozyme-transfected T47D cells. These data provide the first evidence that elevation of ErbB-4 expression plays a role in the proliferation of some ER+ human breast cancer cell lines (T47D and MCF-7) that express high levels of ErbB-4. We have also investigated the expression of ErbB-4 in human primary breast carcinoma specimens, using immunohistochemical staining with an anti-ErbB-4 monoclonal antibody. ErbB-4 expression was found in 60% of the 50 primary breast tumors examined, and high intense immunoreactivity of ErbB-4 was detected in 18% of these primary breast tumors. ErbB-4 receptor expression appeared to correlate with ER+ primary breast tumors. A similar correlation was also observed in the human breast cancer cell lines. These results provide a better understanding of the biological significance of ErbB-4 receptor in breast cancer. Our data suggest that elevation of the ErbB-4 receptor plays a role in ER+ breast cancer cell proliferation. Moreover, ribozyme technology provides a useful tool to delineate the role of a particular gene product.

In vitro and in vivo evaluation of a new polysulfone membrane for hemodialysis. Reference methodology and clinical results. (Part. 2: in vivo study)

Different high flux membranes have been recently developed. The present study is aimed at describing the technical features and the clinical performances of a new high flux polysulfone membrane (T-sulfone, Toray, Japan). The study has been carried out on two different dialyzers (surface area = 1.3 and 1.8 m2). The filters have been tested in vivo during hemodialysis and hemodiafiltration. The in vivo study was carried out on 12 ESRD patients on regular hemodialysis treatment. The protocol was reviewed and approved by the local ethical committee. The in vivo clearances (K) at 300 ml/min of blood flow are reported in the following Table: [Table in text]. Beta-2-m reduction ratio exceeded 50% in all sessions. Beta-2-m mass balance executed by collection of spent dialysate and elution from the used filters evidenced that removal is obtained mostly by filtration while absorption is negligible. Excellent tolerance and hemocompatibility was observed in all the studied sessions.

In vitro and in vivo evaluation of a new polysulfone membrane for hemodialysis. Reference methodology and clinical results. (Part 1: in vitro study)

Different high flux membranes have been recently developed. The present study is aimed at describing the technical features and the clinical performances of a new high flux polysulfone membrane (T-sulfone, Toray, Japan). The study has been carried out on two different dialyzers (surface area = 1.3 and 1.8 m2). The filters have been tested in vitro under definite experimental conditions. The hydraulic flow resistance, the pressure drop in the blood compartment and the hydraulic permeability have been determined in a wide range of in vitro experimental conditions. The in vitro sieving coefficients for various solutes have also been determined utilizing human blood. Hydraulic permeability was found in the range of 28.4 ml/h/mm Hg/m2 and sieving coefficients were between 0.96 and 1.0 for all low molecular weight solutes. The sieving coefficient for inulin was 0.95. The pressure drop in the filter at 300 ml/min of blood flow was 95 mm Hg for the 1.3 m2 and 57 mm Hg for the 1.8 m2. The filters are then designed to operate in the presence of high blood flows without excessive resistance in the blood compartment. The blood compartment analyzed by means of a special radiological sequence obtained with a helical scanner after dye injection confirmed the homogeneous distribution of the blood flow in several cross sections of the bundle. Adequate distribution of dialysate was confirmed with a similar method applied to the dialysate compartment. The new imaging techniques utilized were greatly helpful to determine adequacy of filter design and flows distribution.

[Comparison of combined treatment for venous ulcers in postphlebitic syndrome and use of PGE-1--introductory remarks]

We have included PGE-1 to the clinical management of varicose ulcers of the leg. We found the results very interesting and promising. The literature on using PGE-1 for this disease entity is rather poor and the biomechanics is still unclear.

Are omphalocele and neural tube defects related congenital anomalies?: Data from 21 registries in Europe (EUROCAT)

We have analyzed the association between omphalocele and neural tube defects (O/NTD) previously reported in epidemiological studies of EUROCAT registry data [Dolk et al., 1991; Calzolari et al., 1995]. By examining differences in prevalence between the United Kingdom and Ireland (UKI) and Continental Europe and Malta (CEM) and differences in sex ratio, the possible etiopathogenetic differences between O/NTD association and omphalocele without NTD and NTD without omphalocele were investigated. The distribution of O/NTD cases according to NTD site in the two geographic areas shows in the UKI a tendency for omphalocele to associate with anencephaly/spina bifida and with anencephaly. In CEM centers, these types of NTD are much rarer. The pattern of other anomalies occurring in combination with O/NTD association in the same babies was also analysed.

Inheritance of cleft palate in Italy. Evidence for a major autosomal recessive locus

Although several studies have demonstrated familial aggregation of nonsyndromic cleft palate (CP), the mode of inheritance still remains uncertain. We report the results of complex segregation analysis performed in families of 357 consecutive newborns affected with nonsyndromic CP (i.e., CP not a component feature of malformation syndrome, sequence or association), and registered in the North East Italy and Emilia Romagna congenital malformation registries in the period 1981-1993. This sample, based on a large number of consecutive births, in a well-defined geographical area, with quality control to detect associated anomalies and malformation syndromes, is independent of the number of affected subjects in the family and of CP severity, fitness, and survival. We have analyzed, using the mixed model, the whole sample of nonsyndromic CP, including isolated (i.e., without other anomalies) CP (CPI) and CP associated with at least one other anomaly (CPA), for which a diagnosis of malformation syndrome was not possible. When nonsyndromic CP (including CPA) are considered in the analysis, there is no heterogeneity between CPA and CPI nor between CP including hard palate (CPH) and CP of the soft palate only (CPS). POINTER and COMDS programs cannot discriminate between alternative genetic models; only the hypothesis of non-genetic transmission is rejected. The COMDS analysis two-locus model, which indicates that a modifier locus (or loci) operates in addition to a single major locus (SML), does not show evidence of better fit than SML, polygenic, and multifactorial models. When the severity parameter (defined as CPH and CPS) is added, CPI and CPA show heterogeneity. Eventually, when the analysis is limited to CPI and includes information on severity, a recessive SML, with low penetrance and determining CPH, provides a significant best fit. To have defined a genetic model for CPI and provided evidence for SML inheritance suggests that genetic linkage studies could be implemented. This conclusion is in agreement with previous studies which showed a significant association between alleles of transforming growth factor alpha and CP only in humans, and that single recessive genes may play a crucial role during palatogenesis in mice as well as in Brittany spaniels. Application of the candidate genes to human CPH families could reveal whether these genes are involved.

Rett syndrome in northern Tuscany (Italy): family tree studies

Four cases of Rett syndrome were ascertained among 19,060 girls born between 1978 and 1990 in a small, defined area of Northern Tuscany (Italy) (prevalence rate of 2.1 per 10,000). A fifth girl with a reported clinical picture of Rett syndrome, born in 1978 and deceased at age 13, was also found. One of the four Rett syndrome cases had a healthy female dizygote twin. Family tree studies going back as far as the 17th century were performed. A number of common ancestors were found in different generations leading to a single family tree encompassing all four Rett syndrome cases. In addition, a Rett girl with preserved speech, born in 1974, was found as part of this family tree. These observations confirm the role of genetic factors in the etiology of Rett syndrome and support the hypothesis that Rett syndrome is a clinically variable phenotype.

Urinary tract abnormalities (UTA) and associated malformations: data of the Emilia-Romagna Registry. IMER Group. Emilia-Romagna Registry on Congenital Malformations

An epidemiological study on the urinary tract anomalies (UTA) associated with other congenital malformations or syndromes ascertained by the Emilia-Romagna Registry on Congenital Malformations (IMER) among 209,882 consecutive births monitored during the period 1981-1990 is presented. UTA were ascertained in 349 infants for a rate at birth of 16.6 per 10,000 total births, or one case for every 600 births. The occurrence rate of UTA increased significantly during the ten years of monitoring passing from 6.1 per 10,000 in 1981-1982 to 25.1 in 1989-1990 (r = 0.85; p < 0.001). This increase is in connection with a progressively higher notification of isolated cases of UTA, directly related to the impact of the prenatal diagnosis. Among the 349 cases, 106 (30.4%) were associated with other conditions, including 18 who had chromosomal aberrations (ChrA). The incidence in the total number of the ChrA registered was 43.6 per 1,000. Genetic syndromes (GS) in 33 cases with a specific rate of 150 per 1,000, and 55 cases of multiples with a specific rate of 205.2 per 1,000. In multiples we observed some preferential associations of UTA with intestinal defects and severe ear defects (p < 0.001) and for Central Nervous System and heart defects (p < 0.05). UTA are often associated with other extrarenal defects and sometimes are a component of syndromes that are difficult to identify and for which genetic implications are great and genetic counselling necessary. Pediatricians need to be aware of the possible involvement of the kidney in specific and rare syndromes, and pediatric nephrologists must recognize the association of renal diseases with abnormalities in other physiological systems.

Hydrocephalus, skeletal anomalies, and mental disturbances in a mother and three daughters: a new syndrome

We report on a family in which a mother and her 3 daughters have delayed psychomotor development and/or psychosis, hydrocephalus with white matter alterations, arachnoid cysts, skeletal anomalies consisting of brachydactyly, and Sprengel anomaly. Biochemical and cytogenetic analyses were normal on all 4 patients. The pattern of inheritance, clinical manifestations, and variability of expression suggest that this is a new hydrocephalus syndrome possibly transmitted as an X-linked dominant trait.

Omphalocele and gastroschisis in Europe: a survey of 3 million births 1980-1990. EUROCAT Working Group

A total of 732 cases of omphalocele and 274 cases of gastroschisis was registered in 21 regional registers in Europe (EUROCAT registers) during the period 1980-1990. The total prevalence rates were 2.52 per 10,000 for omphalocele and 0.94 per 10,000 for gastroschisis. There was significant heterogeneity in total prevalence rates among regions for omphalocele. Consistently higher than average total prevalence rates of omphalocele were found in the five centers of the British Isles. This was in large part linked to the association between omphalocele and neural tube defects. A significant female excess among the cases of omphalocele associated with neural tube defects, in comparison with an insignificant male excess for other cases of omphalocele, was observed. Geographical differences in the total prevalence of gastroschisis are partly explained by differences in maternal age distributions in the populations surveyed. Omphalocele was an isolated malformation in 46% of cases; gastroschisis was isolated in 79% of cases. The average birthweight and gestational age of both isolated and multiply malformed cases of both omphalocele and gastroschisis were low, especially for multiply malformed cases, and to a greater extent for isolated gastroschisis than for isolated omphalocele. Prenatal diagnosis leading to termination of pregnancy was reported in 33.2% of omphalocele and in 26.5% of gastroschisis cases, demonstrating the considerable impact of current prenatal screening programs. On the basis of clinical manifestations, epidemiologic characteristics, and the presence and type of additional malformations, omphalocele and gastroschisis can be considered heterogeneous conditions.

Complex segregation analysis in a sample of consecutive newborns with cleft lip with or without cleft palate in Italy

The mode of inheritance of cleft lip with or without cleft palate (CL/P) has been extensively investigated, but the results are controversial. We report results of complex segregation analysis performed in the families of 636 consecutive newborns with CL/P registered in the northeast Italy and Emilia Romagna congenital malformation registries to test hypotheses regarding CL/P inheritance. The programs POINTER and COMDS have been used. POINTER could not distinguish between alternative genetic models, and only the hypothesis of no familial transmission could be rejected. COMDS results, after inclusion of the severity parameter, rejected the hypotheses of a single major locus and were consistent with the two-locus model with a major dominant locus and at least one modifier locus.

Internal irradiation from nuclear medicine investigations: a comparison between effective dose equivalent and effective dose

ICRP Publication 60 (1990) proposes a partially revised method to calculate effective dose, a quantity previously defined in ICRP Publication 26 (1977) as effective dose equivalent. The authors applied these two different approaches to calculate the effective dose equivalent and the effective dose, in the case of internal irradiations from the most common nuclear medicine investigations. The results show clear differences between the two examined quantities, even if the differences are not statistically significant.

On line filtration of dialysate: structural and functional features of an asymmetric polysulfone hollow fiber ultrafilter (Diaclean)

The endotoxin transfer across dialysis membranes has been investigated using specific in vitro circuits. Backdiffusion and backfiltration have been analyzed and most dialysis membranes have shown to be permeable to LAL positive substances. Synthetic membranes however display the better capacity of retention of these products despite their higher porosity and permeability. For such reason synthetic polysulfone ultrafilters are used as pyrogen filters to obtain ultrapure dialysate. We have investigated the characteristics of a polysulfone ultrafilter named Diaclean and manufactured by Amicon Ireland. The capacity of endotoxin retention has been investigated both in filtration and backfiltration modes on new and used ultrafilters. The capacity of endotoxin adsorption was investigated as well. Used ultrafilters appeared to maintain the retention capacity and the adsorption capacity up to 4 months of use. Only slight differences were noted from the baseline values (p = n.s.). The best adsorption capacity is always displayed by the outer layer of the membrane suggesting its best utilization in back filtration mode with tangential flow. No morphological changes were observed in the used membrane analyzed by scanning electron microscopy.

Double pass dialysis: a new method of renal replacement in patients with malfunctioning vascular access

Several patients undergoing chronic renal replacement therapy present problems related to their vascular access. Low blood flows and high rates of recirculation are common in such patients in which, for this reason, it becomes difficult to apply highly efficient techniques or techniques where diffusion and convection are combined as in hemodiafiltration. In these patients we studied the possibility of partially recirculating the blood in the extracorporeal circuit in order to increase the flow rate per single hollow fiber; we defined our system "double pass dialysis". We evaluated the system's efficiency in 12 patients during 24 dialysis sessions: 12 high flux dialysis sessions (without reinfusion) and 12 hemodiafiltration sessions (9 liters reinfusion). Different surfaces of polyacrylonitrile dialyzers were utilized (1.3-1.7-2.1 sqm) at 250 and 350 ml/min of blood flow with or without 100 ml/min of recirculation. During each dialysis session blood and dialysate samples were taken in order to calculate BUN, Creatinine, Phosphate and Inuline clearances from both the blood and dialysate side. The clearances of low molecular weight solutes were not really influenced by the artificial increase of the blood flow, but on the other hand, the clearances of higher molecular weight solutes increased from 10 to 30% during both high flux dialysis and hemodiafiltration with recirculation. This increase was evident mostly in hemodiafiltration suggesting that the cleaning effect on the membrane has a positive impact on the permeability. The good clinical results obtained with the double pass dialysis show that the system is safe and reliable and may become a valid support in critical situations in order to reach adequate dialysis treatment.

766 cases of oral cleft in Italy. Data from Emilia Romagna (IMER) and northeast Italy (NEI) registers

Epidemiological and genetic variables for oral clefts were analysed for the years 1981-1989 in a case-control study of congenital malformations in the Emilia Romagna, Veneto, and Friuli regions, and in the Trento and Bolzano hospitals. Birth prevalence for all cases of cleft lip with or without cleft palate (CL(P)) was 8.2 per 10,000 births, and that for cleft palate only (CP) was 6.1 per 10,000. Coexisting abnormalities were found in 23% of CL(P) cases and in 43% of CP. No clusters in time or space were detected. For isolated clefts, a predominance of males among CL(P) and of females among CP was found; epilepsy was the only maternal risk factor correlated with clefts, and an association between clefting and consanguinity was found. Empirical recurrence risks were calculated in both isolated CL(P) and CP.

Ultrafiltration and clearance studies in human isolated peritoneal vascular loops

Eight samples of human peritoneal tissue were obtained from patients undergoing hemicholectomy for cancer. An artery and a vein were cannulated and perfused with blood in vitro with a special circuit able to provide different perfusion pressures. Ultrafiltration and clearance studies were performed in these samples. Both ultrafiltration and small-solute clearances linearly correlated with the blood flow, demonstrating a strong dependence on this parameter. The peritoneal capillary showed a typical filtration pressure equilibrium with a constant filtration fraction at different blood flows. The results suggest that the blood flow may be a factor limiting the efficiency of peritoneal dialysis both in terms of mass transfer coefficients and maximal ultrafiltration rates.

A new blood module for continuous renal replacement therapies

A new blood module for continuous renal replacement therapies has been utilized to perform CVVH in critically ill patients. The features of the new module named (HP300 and manufactured by Medica srl (Medolla, Modena) are the easy installation and transportability to the bedside, the simple and safe management and the continuous measurement of the pre and post filter pressure with automatic calculation of the end-to-end pressure drop inside the filter. The last feature permits to detect early malfunctions of the filter due to fibers clotting or due to the internal coating of the hollow fibers by plasma proteins. In both cases the efficiency of the treatment can be reduced because of a significant reduction of the ultrafiltration rates or a remarkable decay of the membrane permeability and solute sieving coefficients. In many cases this reduction is only detected when important effects on solute removal have already occurred. In our experience, the new module permitted the substitution of the filters when early malfunctions were detected and maximal treatment efficiency was therefore guaranteed over extended periods of time.

Adult patients with the nephrotic syndrome: really at high risk for deep venous thromboembolism? Report of a series and review of the literature

BACKGROUND

The reported incidence of thromboembolic episodes in people with nephrotic syndrome (NS) ranges from 6% to 44% and it has been ascribed to the presence of a hypercoagulable state, as suggested by abnormalities of several hemostatic parameters in these patients. However, the results of the studies are often contradictory and fragmented and are rarely based on prospective studies. To assess the incidence of venous thrombosis and the pattern of abnormalities of the hemostatic parameters in NS, we planned a prospective study of a group of patients with NS.

PATIENTS AND METHODS

Thirty-six consecutive patients with NS were enrolled during a 9-month period. Every 4-6 months, clinical history was collected and physical examination was carried out. Blood samples for laboratory investigation were taken at entry into the study and 24 months later. A critical review of the literature was also carried out (Medline database and Current Contents).

RESULTS

During the follow-up (mean 45.2 months), no thrombotic symptoms were recorded, PTT, PT, TT and mean AT-III levels were within the normal range, whereas fibrinogen, plasminogen, protein C and S, heparin cofactor II levels were significantly higher than normal both at entry into the study and 24 months later. No patient was positive for antiphospholipid antibodies. Slightly decreased levels of AT-III and heparin cofactor II were found in only two cases.

CONCLUSIONS

Our study confirms neither the high incidence of thrombotic complications in NS nor the presence of abnormalities of hemostatic parameters commonly associated with venous thromboembolism.