The frictional layer in the observed momentum budget of the trades.

Profiles of eddy momentum flux divergence are calculated as the residual in the momentum budget constructed from airborne circular dropsonde arrays ( ∼ 220 km) for 13 days during the EUREC 4 A/ATOMIC field campaign. The observed dynamical forcing averaged over all flights agrees broadly with European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) forecasts. In the direction of the flow, a mean flux divergence (friction) exists over a 1.5-km deep Ekman layer, and a mean flux convergence (acceleration) is present near cloud tops. The friction is countergradient between 1 and 1.5 km, where vertical wind shear exceeds the observed thermal wind. From the frictional profile, a 10-m momentum flux of ∼ 0.1 N · m - 2 is derived, in line with Saildrone turbulence measurements. A momentum flux divergence in the cross-wind direction is pronounced near the surface and acts to veer the wind, opposing the friction-induced cross-isobaric wind turning. Weaker friction and upper-level acceleration of easterly flow are observed when stronger winds and more vigorous convection prevail. Turbulence measurements on board the SAFIRE ATR-42 aircraft and the Uncrewed Aircraft System (UAS) RAAVEN reveal pronounced spatial variability of momentum fluxes, with a non-negligible contribution of mesoscales (5-30 km). The findings highlight the nontrivial impact of turbulence, convection, and mesoscale flows in the presence of diverse cloud fields on the depth and strength of the frictional layer.

Pancreas transplantation inside Emilia-Romagna, Italy: referral pattern, demand forecasting, and organ availability.

In Italy, referral of diabetic patients for pancreas transplantation (PT) is an unstructured process, resulting in a low rate of activity and late referrals, often when the patient has already undergone dialysis. In addition, the continuous improvement in pancreas transplant alone, offering the opportunity to reduce cardiovascular risk due to proteinuria and reduced glomerular filtration rate (GFR), is rarely appreciated. We therefore analyzed (1) referral activity to PT during the time frame 2001-2005 in Emilia-Romagna, Italy (four million inhabitants), by collecting ICD 9 CM codes (55.69 + 52.80; 52.86 and 52.80 alone) by residence of the patient; (2) demand for PT among a sample population of 1670 diabetes patients, whose charts were reviewed for the type of diabetes and presence of overt diabetic nephropathy (DN: proteinuria >300 mg/24 h and/or GFR <60 mL/min); (3) potential pancreas availability as the ratio between pancreas and hearts utilized (UP/HR) in different areas of our country. As a results, (1) referral activity reached 8.4 PT per million people in 5 years in the whole region, ranging from 2.6 in the province where a PT program is active, to a maximum value of 20.7 in the province where a devoted outpatient clinic is operated by nephrologists. (2) Prevalence of overt DN was 6% in our cohort, corresponding to 510 D1 patients worthy of evaluation for PT inside Emilia-Romagna region. (3) During 2006, UP/HR was 0.58 in Associazione Inter-Regionale Trapianti agency, 1.16 in Tuscany, 0.30 in Piedmont, and 0.26 in our region. Taken together, our data showed that (1) the referral of D1 to PT has to be empowered, keeping in touch with all patients suffering from diabetic nephropathy; (2) the outpatient clinic devoted to evaluation and recruitment of D1 with nephropathy plays the key role in this program of timely and widespread referral; (3) the availability of pancreata can be increased by utilizing broader criteria for harvesting, increased consent rate to donation and increased the demand for PT (recipient pool). Pancreas grafts need to increase, since the current low demand produces underutilization of the pancreas resource, due to the frequent lack of a suitable recipient.

[Early kidney-pancreas transplantation in type 1 diabetics prevents hemodialysis]. / Il trapianto precoce di rene-pancreas previene l'ingresso in dialisi dei diabetici tipo 1.

BACKGROUND: The life-expectancy of type 1 diabetics (T1D) on dialysis is still shorter than that of non-diabetics. Pancreas transplantation (PT) in its different modalities should be considered as a life-saving procedure. METHODS: We analyzed our referral activity of T1D to PT from 1992. Since 2002, we have created a kidney and diabetes out-patient clinic devoted to the prevention of diabetic nephropathy and to the early referral of suitable T1D to combined kidney- pancreas transplantation (KPT) and isolated pancreas (PTA). RESULTS: In the last 14 yrs, 25 T1D underwent KP in our district (620000 inhabitants). At the beginning, KPT was performed abroad, but then the borders were closed. After stopping in the mid 1990s, KP activity restarted addressing preemptive KPT and PTA. Currently, only one patient is on dialysis while awaiting KPT. Four T1D were evaluated and excluded from the list on medical grounds; two patients are on the list and a further two patients are currently under evaluation. CONCLUSIONS: The implementation of a cooperative network among dialysis and transplant centers, supported by devoted out-patient clinics allowed the effective prevention of the dialysis requirement in T1D. Out-patient clinics devoted to diabetic nephropathy should play a pro-active role in preemptive KP, including the 'new' option of islet transplantation according to the Edmonton protocol.

Prevalence of hepatitis C virus (HCV) antibodies in haemodialysis patients.

The prevalence of antibodies to HCV and the course of hepatitis have been determined in 357 haemodialysed patients treated at a single institution. The prevalence of HCV infection increases with the duration of haemodialysis and with the use of blood transfusions, yet there is high frequency of HCV seropositivity even without blood transfusions. Evolution of HCV hepatitis to chronicity is frequent and biological signs of chronic hepatopathy can coexist with absence of alanine aminotransferase (ALT) abnormalities.

Cryoglobulinemia in HCVAb+ patients on chronic hemodialysis.

OBJECTIVE: Striking evidence of HCV infection has been found in mixed cryoglobulinemia (MC) and HCV has been hypothesized to be the causative agent of this disease. To assess the association of C virus infection and cryoglobulinemia we studied cryoglobulin levels in 66 patients on maintenance hemodyalisis who were selected on the basis of HCVAb positivity and not because they were affected by liver disease. The control group was made up of 45 patients also on hemodyalisis but without HCV infection. RESULTS: Circulating cryoglobulins were found in 34 (52%) of 66 HCV+ patients: the cryocrit was < 1% in 20, 1 to 5% in 12, and > 5% in 2 patients. The cryoglobulins were classified by immunofixation as type II in 8 and type III in 8 others; identification was not possible in 18 cases. In the HCVAb- control group untypable cryoglobulins were detected in 9% of the patients at < 1% by volume. No correlation was found between these data and the liver disease detected by biohumoral tests. CONCLUSIONS: Our data confirm the close link between HCV infection and cryoglobulins; the prevalence of circulating cryoglobulins in uremic HCVAb+ patients is very close to that found in HCV-related liver disease.

[HCV+ patients on the waiting list for kidney transplantation. Retrospective analysis of data on the patient population with hepatitis C on the waiting list for kidney transplantation in the setting of the AIRT]. / Pazienti HCV+ in lista d'attesa per trapianto renale. Analisi retrospettiva dei dati relativi alla popolazione dei pazienti affetti da epatite C in lista d'attesa per trapianto di rene in ambito AIRT.

BACKGROUND: HCV infection in hemodialysis is still a matter of debate from an epidemiological and clinical point of view. Evaluation criteria for HCV-infected patients as transplant candidates are still not adequately standardized. Aims of the present study were to investigate: 1. the percentage of HCV positive patients on the waiting list of three Italian regions belonging to the Associazione InterRegionale Trapianti (AIRT); 2. to analyze the clinical approach in the evaluation of these patients in the attempt to define national guidelines for their pre- and post-transplant management. PATIENTS: We evaluated 2045 uremic patients on the waiting lists of four transplant centers (Bari, Bologna, Modena, Novara) belonging to AIRT at 31/12/2002. RESULTS: The overall prevalence of HCV positive patients was 14.2%, with a peak in the Puglia waiting list. The most common screening tests were AST and ALT serum levels and viral load (HCV RNA). Although there is a clear evidence that histological parameters are the main diagnostic and prognostic markers, a liver biopsy was performed in only 9.5% of patients. An even smaller percentage of HCV-infected patients underwent anti-viral therapy. CONCLUSIONS: Our retrospective analysis evidenced the need to improve common clinical strategies in approaching HCV-infected canditates to renal transplantation in the attempt to improve their post-transplant outcome.

[Malignant neoplasia and kidney transplantation. Retrospective analysis of data on the population having kidney transplantation with de novo neoplasia in the setting of the AIRT]. / Trapianto renale e neoplasie. Analisi retrospettiva dei dati relativi alla popolazione dei trapiantati di rene affetti da neoplasie de novo in ambito AIRT.

BACKGROUND: In transplanted patients undergoing immunossuppressive therapy the incidence of malignant neoplasia is 3-4 times higher than in the general population. Aim of the present study was to evaluate the prevalence of different tumours and the links between modulation of immunosuppressive therapy and patient and graft survival. PATIENTS: We evaluated 2029 kidney-transplanted patients from four Transplant Centres (Bari, Bologna, Modena, Novara) belonging to the Associazione InterRegionale Trapianti (AIRT). RESULTS: The incidence of neoplastic disease after transplantation was 3.9% in our population with a median time between transplantation and clinical onset of 23 months. We demonstrated a significant difference in the geographical distribution of different tumours. We did not observe any correlation with specific immunosuppressive drugs. Finally, dramatic reduction of the immunosuppression levels did not modify either the patients' or the graft's survival. CONCLUSIONS: Several factors can influence the post-transplant onset of neoplastic diseases with immunosuppressive therapy playing a pivotal role. The implementation of a National Registry would be the first step in an attempt to optimise immunosuppression in this particular group of patient's.

Long-term use of a "stable" bicarbonate containing dialysate.

We present an original method for the preparation of "stable" dialysate containing 35 mEq/l of bicarbonate. The dialysate was utilized with 4 patients for periods ranging from 4 months to 1 year according to a short-term recirculated dialysis schedule in closed circuit (20-40L) (2-2 1/2 hrs) on alternate days. Preliminary results are reported here with respect to the tollerance of the dialytic run and correction of the acid-base balance equilibrium. The clinical tollerance is excellent despite high dehydration rates even in patients particularly sensitive to ultrafiltration. The acidosis correction would seem to be much better with bicarbonate than with traditional dialysis. The difference is even higher if we consider the brevity of the dialysis. During the bicarbonate dialysis we do not observe any fall of the PCO2 or significant difference in PO2 in the patient's blood. The correction of acidosis probably causes the normalization of pre-dialytic potassiemia in spite the "net" removal of K with short dialysis is considerably less.

Which level of cytokine production is critical in haemodialysis?

Monocyte activation with cytokine production is a well known event in the course of dialysis treatment but its relation to symptoms of haemodialysis or long-term pathological changes in chronic dialysis patients is still under discussion. Cytokine production depends on the balance between inducers and inhibitors while effects rely on the peculiar uraemic environment and cell metabolism. 'Foot-prints' for monocyte activation have been found, but no marker for clinical symptoms has been demonstrated clearly. In this scenario it is almost impossible to link a specific symptom to a definite stimulus such as dialysate microbial contamination or membrane complement generation. The topics discussed in this paper include cytokines synthesis modulation factors, levels in haemodialysis patients, and results of finding markers of clinical relevance. Special attention is paid to microbial contamination of dialysis fluid with analysis of cytokine inducing substances in commercial sterile solutions. Data on cytokine synthesis and activity in the aged are also discussed, with special regard to the haemodialysis setting.

Behavior of antibody profile against hepatitis C virus in patients on maintenance hemodialysis.

The prevalence of anti-hepatitis C virus (HCV) in dialysis setting is still a nonstandard datum. In particular, it is not known of the phenomenon is stable or increasing or decreasing, even in a given geographical area. We studied the behavior of anti-HCV prevalence during a 12-month follow-up in 415 hemodialysis patients treated at a single institution and belonging to a limited geographical area with standard HCV endemic. Point prevalence of anti-HCV has shown a tendency to growth linked in part of the incidence of infection, in part to new positivities in patients already on dialysis treatment. More than 50% of the new HCV-positive patients, had no history of classical parenteral transmission of the virus. These findings suggest that HCV infection is a phenomenon on the increase in dialysis units and that dialysis treatment emerges as an independent risk factor in contracting infection.