31P NMR study of Na2CuP2O7: a S=1/2 two-dimensional Heisenberg antiferromagnetic system

The magnetic properties of Na2CuP2O7 were investigated by means of 31P nuclear magnetic resonance (NMR), magnetic susceptibility, and heat capacity measurements. We report the 31P NMR shift, the spin-lattice 1/T1, and spin-spin 1/T2 relaxation-rate data as a function of temperature T. The temperature dependence of the NMR shift K(T) is well described by the S=1/2 square lattice Heisenberg antiferromagnetic (HAF) model with an intraplanar exchange of J/k_B \simeq 18\pm2 K and a hyperfine coupling A = (3533\pm185) Oe/mu_B. The 31P NMR spectrum was found to broaden abruptly below T \sim 10 K signifying some kind of transition. However, no anomaly was noticed in the bulk susceptibility data down to 1.8 K. The heat capacity appears to have a weak maximum around 10 K. With decrease in temperatures, the spin-lattice relaxation rate 1/T1 decreases monotonically and appears to agree well with the high temperature series expansion expression for a S = 1/2 2D square lattice.Comment: 12 pages, 8 figures, submitted to J. Phys.: Cond. Ma

Case Control Study on Dialysis Arthropathy: The Influence of Two Different Dialysis Membranes: Data from the EDTA Registry

In a retrospective case control study the prevalence of signs and symptoms of dialysis osteoarthropathy was analysed. Cases and controls had received over 9 years of maintenance haemodialysis uninterrupted by peritoneal dialysis or transplantation. The cases comprised 55 patients treated predominantly with polyacrylonitrile (AN69) dialysers. They were compared to a matched group dialysed exclusively with cellulosic membranes. Over 60% of all patients, cases and controls, showed one or more signs of disabling osteoarthropathy, with joint pains occurring more frequently in the older age groups. Twenty-seven of the 55 cases who had received less than 2 years of cellulosic membrane dialysis followed by 7-12 years of AN69 dialysis tended to have a lower prevalence of joint pains, carpal-tunnel syndrome and bone cysts. However, no statistically significant differences were obtained compared to the matched control group dialysed exclusively on cellulosic membranes (mostly cuprophane). The remaining 28 cases, who had been treated for more than 2 years with cellulosic membranes preceding the longer treatment period with polyacrylonitrile dialysers, showed a prevalence similar to that of their cellulosic controls. This study thus shows little, if any, influence of the two types of membranes on the prevalence of signs and symptoms of β2-microglobulin amyloidosi

Survival on Renal Replacement Therapy: Data from the EDTA Registry

Extensive survival data are presented from the EDTA Registry's files for patients who started renal replacement therapy in 1970-1974 compared to 1980-1984. The contribution of the different treatment modalities (haemodialysis, continuous peritoneal dialysis, and transplantation) to the survival of patients according to geographical region is also shown. Survival on renal replacement therapy, irrespective of treatment modality and of primary renal disease, was best in the 10-14-year-old patients, with 58% at 10 years and 52% at 15 years, and decreased with rising age to 28% at 10 years and 16% at 15 years in patients aged 45-54 when they commenced therapy in 1970-1974. When comparing the 0-4-year-old with the 10-14-year-old cohort of the paediatric patients, 5-year survival rates for patients starting renal replacement therapy in the early eighties declined from 85% to 70% with decreasing age. Treatment policy, as reflected by the proportion of patients on different modes of therapy, varied markedly between European regions but affected survival to a small extent only. The large population with diabetic nephropathy incurred annual mortality rates 2-3 times greater than those observed in patients with ‘standard' primary renal diseases. Haemodialysis and continuous peritoneal dialysis, although not comparable because of important differences in selection policy, yielded similar survival rates. Patient and graft survival rates have improved markedly when comparing patients starting renal replacement therapy in the early seventies with the eighties; particularly for cadaveric transplantation. Patient survival after second grafting was similar to that after first grafting, with 83% at 5 years after second cadaveric grafting in the 15-44-year-old cohort, vs 85% after first cadaver transplantation in 1980-1984. Second cadaveric graft survival was superior to average first-graft survival for those recipients whose first graft had been functioning for more than 1 year. However, second-graft survival in rapid rejectors of a first graft as well as third cadaveric graft survival were curtailed by the large number of early losses, with only 52% of third grafts functioning at 1 year. For living related donor transplantation, parents were mostly used in children whilst identical siblings predominated in adults older than 45. In the early eighties, patient survival was 92% at 5 years for recipients younger than 15, 87% for the 15-45 year old cohort and 72% for those aged 45 or older. From the overall survival rates on renal replacement therapy obtained at 5 years in the early eighties, it appears safe to predict that at least 65% of young adults and 25% of patients aged 55-64 will be surviving at 10 years after starting therap

Demography of Dialysis and Transplantation in Children in Europe, 1985: Report from the European Dialysis and Transplant Association Registry

At the end of 1985 there were 5482 patients known to the Registry who started renal replacement therapy (RRT) between the ages of 6 months and 15 years. Of these, approximately 25% had died, 30% were still aged less than 15 years, and the other 45% were older. The acceptance rate of new patients over the last 10 years has slowly but steadily increased; six new paediatric patients per million child population probably represents the likely needs of the near future. Hospital haemodialysis remained the main form of renal replacement therapy in new patients, while 3 years after start of RRT, transplantation became the most frequently used replacement therapy; CAPD appeared to be used mainly in children with a short waiting time for transplantation. Out of the 384 grafts reported in 1985, only 16% were from living related donors; among 321 cadaver grafts, 24% were second and only 3% were third grafts. Glomerulonephritis and pyelonephritis accounted for 50% of all primary renal diseases. During the last 5 years, the proportion with glomerulonephritis seems to have decreased slightly. Hyperkalaemia and fluid overload have still to be considered the main causes of death. Only in 17% of all cases was the cause of death reported as unknown or undetermine

Successful pregnancies in women on renal replacement therapy: Report from the EDTA Registry

This study reports the geographical incidence of successful pregnancies in women on renal replacement therapy (RRT) and related information on gestation and clinical status of newborns. The impact of successful pregnancy on graft function was assessed by means of a retrospective case-control study. Since 1977 special questionnaires have been sent to each dialysis and transplant centre which reported babies born to mothers on RRT on the yearly centre questionnaire. After 10 years of data collection, a total of 490 pregnancies and 500 babies were available for analysis. A percentage of 88.4 of the babies were born to mothers with a functioning graft, 11.2% to mothers on chronic haemodialysis, and the remaining 0.4% to mothers on CAPD. Almost 50% of all successful pregnancies werereported from the UK. The number of successful pregnancies increased steadily and in parallel with the increasing number of females of childbearing age with a functioning renal transplant. The majority of mothers delivered at age 24-32. For transplanted mothers delivery occurred most commonly during the 3rd and 4th year after successful transplantation. In approximately 85% of cases the duration of pregnancy was shorter than the lower 10th percentile of normal. Birthweight was reduced in accordance with gestational age. Newborn mortality was 1.8%. Fifty-three mothers with a successful pregnancy in 1984-1987 were computer matched with controls according to a number of criteria. The serum creatinine concentration recorded in coded form at the end of each year on the individual EDTA patient questionnaire was used to assess changes in graft function. In 94% of these cases the serum creatinine, recorded 0-11 months before delivery, did not exceed 160 umol/1. Graft function deteriorated in 18% ofmothers as compared to 24% of controls. Twentyfour to 36 months postpartum, changes of serum creatinine were similar in test cases and controls, suggesting that a successful pregnancy does not adversely affect graft function if this was stable and well preserved at the time of conceptio

Rehabilitation of young adults during renal replacement therapy in Europe: The presence of disabilities

The aim of this study was to analyse rehabilitation during RRT in 617 young adults from different European countries who started dialysis or transplantation before the age of 15 years. The data were derived from the EDTA Registry patient data files and a special questionnaire that was sent to centres reporting to the EDTA Registry. The duration of RRT was more than 10 years in 63% of patients. Fifty-four percent were living with a functioning graft and 46% were on dialysis. The prevalence and severity of motor, hearing, sight, and mental disabilities were analysed retrospectively. They were found to vary according to primary renal disease and method oftreatment. One-third of patients had one or more disabilities at the start of RRT. Although disability status had changed in many patients by 31 December 1986, some disability remained in one-third of the patients available for study. Disabilities were recorded as mild in the majority of patients. Both improvement and worsening of motor and mental disability occurred more often than changes of hearing capacity and sight. It is concluded that prevention and treatment of disabilities need special attention in children and young adults on RRT in order to improve rehabilitatio

Renal Transplantation in Diabetic Patients with or Without Simultaneous Pancreatic Transplantation 1986: Data from the EDTA Registry

This report summarises the outcome of 90 combined kidney/pancreatic grafts performed in Europe in 1986. Data for the combined kidney/pancreas grafts were obtained by a special questionnaire. The one-year patient and kidney graft survival is compared to the results of a group of 389 patients with diabetic nephropathy on the EDTA Registry data file who received kidney grafts alone. The recipients of combined kidney-pancreas grafts were younger, whereas a greater proportion of males received kidney graft alone. Patient survival at one year after transplantation was similar: 89% in recipients of combined transplants compared to 90% in recipients of kidney grafts alone. Kidney graft survival was 78% at one year for recipients of combined grafts versus 76%. It is concluded that pancreas transplantation has little effect on the fate of concomitant kidney grafts. The procedure should - in experienced hands and in selected patients - be almost as safe as kidney grafting alon

Factors influencing anaemia in dialysis patients. A special survey by the EDTA-ERA Registry

The European Dialysis and Transplantation Association—European Renal Association (EDTA-ERA) Registry conducted a special study on anaemia in dialysis patients because it seemed important to elucidate the various factors that influence the degree of anaemia and the use of regular transfusions in dialysis patients before the introduction of recombinant human erythropoietin (rHuEpo) for larger groups of patients. In a 20% sample of all patients recorded to have been dialysed throughout 1987, statistically significant associations could be found by multifactorial analysis between haemoglobin (Hb) concentration and age, sex, primary renal disease, type of treatment, hours of dialysis per week, and number of years on renal replacement therapy. The type of dialyser membrane did not seem to play a role (although there was weak evidence of an effect of the dialyser). Mean Hb concentration for dialysis patients differed between countries as did the transfusion policy. In view of the high costs of the rHuEpo treatment and potential side-effects, factors such as method of dialysis and hours of haemodialysis per week should be taken into consideration in the treatment of anaemia in dialysis patient

On the Spiral Structure of the Milky Way Galaxy

We consider the possible pattern of the overall spiral structure of the Galaxy, using data on the distribution of neutral (atomic), molecular, and ionized hydrogen, on the base of the hypothesis of the spiral structure being symmetric, i.e. the assumption that spiral arms are translated into each other for a rotation around the galactic center by 180{\deg} (a two-arm pattern) or by 90{\deg} (a four-arm pattern). We demonstrate that, for the inner region, the observations are best represented with a four-arm scheme of the spiral pattern, associated with all-Galaxy spiral density waves. The basic position is that of the Carina arm, reliably determined from distances to HII regions and from HI and H2 radial velocities. This pattern is continued in the quadrants III and IV with weak outer HI arms; from their morphology, the Galaxy should be considered an asymmetric multi-arm spiral. The kneed shape of the outer arms that consist of straight segments can indicate that these arms are transient formations that appeared due to a gravitational instability in the gas disk. The distances between HI superclouds in the two arms that are the brightest in neutral hydrogen, the Carina arm and the Cygnus (Outer) arm, concentrate to two values, permitting to assume the presence of a regular magnetic field in these arms.Comment: 21 pages, 14 fugures; accepted for publication in Astronomichesky Journal (Astron. Rep.

Rehabilitation of young adults during renal replacement therapy in Europe: 2. Schooling, employment, and social situation

The educational status, employment rate and social situation were studied in 617 patients between 21 and 35 years of age who started renal replacement therapy (RRT) as children. The data were derived from a special questionnaire concerning disability and rehabilitation sent to dialysis and transplant centres reporting to the EDTA Registry. Fifty-six percent of patients completed secondary school and one in three went on to vocational training. Eleven percent of patients attended university, and 16% were reported to have gone to a special school for the handicapped. Up to one-third of patients who attended different school types failed to complete their education. There were notable geographical differences in schooling and in employment. Fifty-six percent of all patients were employed. Lack of schooling was considered to be a major reason for unemployment. Sixty-one percent of patients with disabilities and 34% without disabilities were receiving invalidity payments. The place of residence of these patients aged 21-35 was usually the parental home. Compared to the general population of similar age, only a few patients were married (13.5% of the total study group) and 8% had children. In summary, the present report shows that the major factors influencing rehabilitation on RRT are the presence of disabilities, the method of treatment, geographical factors, duration of RRT, and the underlying primary renal diseas