Acute chest syndrome in children with sickle cell disease: Data from a national AIEOP cohort identify priority areas of intervention in a hub-and-spoke system.

Acute chest syndrome (ACS) is a frequent cause of hospitalization in sickle cell disease (SCD). Despite advances in acute care, many settings still lack knowledge about ACS best practices. After the AIEOP Guidelines were published in 2012, suggesting standardized management in Italy, a retrospective study was performed to assess the diagnostic and therapeutic pathways of ACS in children. From 2013 to 2018, 208 ACS episodes were presented by 122/583 kids in 11 centres. 73 were male, mean age 10.9 years, 85% African, 92% HbSS or Sß°. In our hub-and-spoke system, a good adherence to Guidelines was documented, but discrepancies between reference centres and general hospitals were noted. Improvement is needed for timely transfer to reference centres, use of incentive spirometry, oxygen therapy and pain management.

Influence of individual or group housing of newborn calves on rotavirus and coronavirus infection during the first 2 months of life.

Bovine rotavirus A (RVA) and bovine coronavirus (CoV) are the two main viral enteropathogens associated with neonatal calf diarrhea. The aim of the present work was to study the impact of group and individual housing systems in the epidemiology of RVA and CoV infection. Eleven calves reared in individual housing (FA) and nine calves in group housing (FB) were monitored during the first 7 weeks of life. Stool and serum samples were screened for RVA and CoV antigens by ELISA. IgG1 antibodies (Ab) to both antigens were also measured. From the 160 fecal samples collected, the proportion of positive samples to RVA and CoV was significantly higher in FB (23.6%) than in FA (9%) (p = 0.03). The geometric mean of colostral IgG1 Ab titers to CoV and RVA in FA (IgG1 anti-CoV 1024 and anti-RVA 1782.9) was lower than in FB (IgG1 anti-CoV 10,321.2 and anti-RVA 4096) at birth. Calves less than 2 weeks of life from FB had a higher risk of being infected by RVA (OR = 4.9; p = 0.01) and CoV (OR = 17.15; p = 0.01) than calves from FA. The obtained results showed that there was higher RVA and CoV shedding in group-housed calves than in individual-housed animals.

First report of group A rotavirus and bovine coronavirus associated with neonatal calf diarrhea in the northwest of Argentina.

Group A rotavirus (RVA) and bovine coronavirus (BCoV) are the two main viral enteropathogens associated with neonatal calf diarrhea. The aim of the present survey was to investigate the epidemiology and the role of RVA and BCoV in the presentation of dairy and beef calf diarrhea in Lerma Valley of Salta province, within the Northwest region of Argentina. Stool samples of calves with or without diarrhea younger than 2 months of age were collected from 19 dairy farms and 20 beef farms between the years 2014 and 2016. Stool samples were screened for RVA and BCoV detection by ELISA. Heminested multiplex RT-PCR was used for RVA typing and RT-PCR to confirm BCoV. Positive samples were submitted to sequencing analysis. Bovine RVA and BCoV were circulating in 63% (12/19) and 10.52% (2/19) of the dairy farms, respectively, where 9.5% (46/484) of the calves were positives to RVA and 0.4% (2/484) to BCoV. In beef herds, RVA was detected in 40% (8/20) of the farms and in 6.75% (21/311) of the calves, without positives cases of BCoV. Molecular analysis showed that in dairy farms, G6P[11] and G10P[11] were the prevalent RVA strains, while in beef farms, G10P[11] was the prevalent. The main finding was the detection for the first time of a G15P[11] causing diarrhea in beef calves of Argentina that represents a new alert to be consider for future vaccine updates. Analysis of detected BCoV showed that it is related to the other circulating strains of Argentina.

Renin angiotensin system blockade and activated vitamin D as a means of preventing deep vein thrombosis in renal transplant recipients.

BACKGROUND: Venous thromboembolism (VTE) is one of the thrombotic complications that occur in renal transplant recipients (RTR). The observation that vitamin D receptor activators, angiotensin-converting enzyme inhibitors (ACEi), and angiotensin receptor blockers (ARBs) have a protective effect against protrombotic state suggests that their possible combination could reduce the incidence of VTE in RTR. OBJECTIVES: to evaluate the incidence of VTE in RTR and the timing of occurrence after renal transplantation (Tx); to compare the incidence of VTE in our RTR and RTR on calcitriol, ACEi, ARBs and their combination therapy. Risk factors were also evaluated. RESULTS: During follow-up, 96 of 769 RTRs, 73 males 23 females, developed a first episode of VTE: 23 in the first 3 months after Tx; 15 from 3 to 6 months; 9 from 6 to 12 months; 13 from 12 to 48 months and 36 after more than 48 months. The incidence was significantly lower in RTR on treatment with a combination of calcitriol 0.25 µg/day, an ACEi and an ARB and in RTR on treatment with only calcitriol 0.5 µg/day (9.4% and 9%, respectively, vs. 14.5% (p < 0.05)). However, the most decreased rate (5.6% vs. 14.5% (p < 0.01)) was in patients treated with a combination of calcitriol 0.5 µg/day, an ACEi and an ARB. CONCLUSION: A combination therapy with calcitriol 0.5 µg/day, ACEi, and ARB is associated with a 60% lower rate risk of VTE.

Keratinocyte cancer prevention with ACE inhibitors, angiotensin receptor blockers or their combination in renal transplant recipients.

BACKGROUND: Skin cancer (SC) is the most frequent malignancy after renal transplantation (RT), especially squamous and basal cell carcinoma. The observation that angiotensin II is a potent angiogenic and growth factor raises the possibility that blocking its effects could reduce the incidence of skin cancer. OBJECTIVES: To evaluate the incidence of keratinocyte cancer in RT recipients, the timing of occurrence of the skin events after RT; to compare the incidence of SC in our RT recipients and in RT patients on angiotensin converting enzyme inhibitors (ACEi), angiotensin receptor blockers therapy (ARBs) and their combination. Risk factors were also evaluated. RESULTS: During follow up, 52 of 565 patients (9.2%), 38 males 14 females, developed SC at a median time of 59 months (range 29 - 74) after RT. 12 of 52 patients (23%) with SC were on ACEi, ARBs therapy or their combination. The incidence was significantly lower in user patients compared to non user (5.6% and 11.4% respectively). BCC was the most frequent type of keratinocyte cancer in non users and in users. No association with incidence of BCC or SCC was observed for other classes of antihypertensive drugs (calcium antagonists, beta-blockers, alpha-blockers). CONCLUSION: This study confirms that RT patients are at high risk of SC. The use of ACEi or ARBs is associated with an approximately two-fold reduced risk of Keratinocyte cancers compared to non users in RT recipients. We did not observe an association between the incidence of SC and the use of other classes of antihypertensive drugs. Any chemoprotective effect of these agents may reflect inhibition of the growth factor activity of angiotensin II. Use of ACEi or ARBs, when this is possible, should be considered in RT patients with multiple risk factors.

Disseminated Scedosporium apiospermum infection in renal transplant recipient: long-term successful treatment with voriconazole: a case report.

Scedosporium apiospermum, the asexual form of Pseudallescheria boydii, is a ubiquitous fungus that represents an unfrequent complication of immune suppression. It accounts for 20% of all non-Aspergillus mold infections in organ transplant recipients. The infection can be localized or disseminated in multiple organs, including lungs, brain, joints, tendons, and skin, and is difficult to treat, due to resistance of S apiospermum to amphotericin B and other antifungal agents. The mortality rate is about 50%. To our knowledge, there are no prospective studies or registries of transplant recipients to guide diagnosis and there are no evidence-based recommendations for the optimal management of this infection. We report a case of S apiospermum infection in a woman with renal transplantation. The first occurrence of infection was a solitary nodule on the forearm, which was surgically excised. Two following relapses were disseminated to the knee, the Achilles tendon, and the skin of the left leg. The infection was successfully treated with voriconazole, but due to the severe iatrogenic immune suppression, a strong reduction in immunosuppressant drugs was needed.

Renal transplant recipients are at high risk for both symptomatic and asymptomatic deep vein thrombosis.

BACKGROUND: Venous thromboembolism (VTE) is one of the thrombotic complications that can occur in patients receiving renal transplantation (RT). The prevalence of VTE in RT patients is, however, undefined. OBJECTIVES: To evaluate the rate of a first episode of VTE in a series of 538 consecutive RT recipients admitted to our institution, the timing of occurrence of the thromboembolic events after transplantation, and the rate of recurrence after thromboprophylaxis withdrawal. Risk factors for recurrence were also evaluated, particularly in relation to the type of the first event (symptomatic or asymptomatic). RESULTS: During follow-up, 47 of 518 patients (28 males, 19 females; 9.1%) developed a first episode of VTE at a median time of 17 months (range 1-165 months) after kidney transplantation. Cancer was associated with the occurrence of VTE (odds ratio 4.8). Seventeen of 43 patients (39.5%) with deep vein thrombosis were asymptomatic and the diagnosis was made during routine ultrasound examination. Twenty-two patients (46.8%) experienced a recurrence of VTE. A relevant rate of recurrence was documented amongst patients with a first episode of both symptomatic (53%) and asymptomatic (23.5%) VTE. CONCLUSION: This study confirms that RT patients are at high risk of symptomatic and asymptomatic VTE and that this risk persists even after several years. Patients who experience VTE are at high risk of recurrence after thromboprophylaxis withdrawal.

Long-term administration of enteric-coated mycophenolate sodium (EC-MPS; myfortic) is safe in kidney transplant patients.

BACKGROUND: To date, there are no data on long-term use of enteric-coated mycophenolate sodium (EC-MPS; myfortic) from time of renal transplantation. We report the first long-term safety and efficacy data on EC-MPS when administered for up to 3 years post transplant. METHODS: De novo renal transplant recipients completing 1 year of treatment in a multicenter, randomized, double-blind trial of EC-MPS versus mycophenolate mofetil (MMF) were invited to take part in an open-label extension during which all patients received EC-MPS 720 mg b.i.d. Results from the period 12 - 36 months post transplant were compared to comparable data from MMF-treated patients taking part in two studies of everolimus versus MMF (RAD 201 and RAD 251). RESULTS: Of 367 patients completing the blinded core study, 247(62%) entered the open-label extension phase. During the first 24 months of the extension, the incidence, type and severity of adverse events were comparable between the newly-exposed and long-term EC-MPS patients. There were 2 deaths in the newly-exposed group and 4 among long-term EC-MPS patients, with 1 and 2 graft losses, respectively. Six patients (5%) in the newly-exposed group and 4 (3%) in the long-term EC-MPS group experienced biopsy-proven acute rejection. Cross-study comparisons indicated that the tolerability profile of EC-MPS was similar to MMF, including the incidence of adverse events, infections and malignancies, as was the incidence of efficacy events. CONCLUSION: These results demonstrate that EC-MPS with cyclosporine and steroids provides good long-term efficacy and tolerability, and confirm the safety of converting renal transplant patients from MMF to EC-MPS.

Low 1-year cyclosporine microemulsion doses are associated with better 5-year renal graft function: an insight from MOST, a multinational observational study.

BACKGROUND: In earlier registry analyses, cyclosporine at doses of < 3 mg/kg/d at 1 year post-renal transplantation has been associated with significant graft loss or reduction in renal function. Improvements in cyclosporine formulation with increased bioavailability, plus the use of more efficient comedications, may now confer better outcomes. To determine the effect of the 1-year cyclosporine microemulsion (CsA-ME) dose on renal allograft function at 5 years, we analyzed data collected from 2889 patients with documented graft survival to year 5 in a prospective, multinational, observational study-Neoral MOST. RESULTS: Glomerular filtration rate (GFR) at year 1 was 63 +/- 20 mL/min and 59 +/- 22 mL/min at year 5. The multivariate analysis including year 1 CsA-ME dose as factor and GFR at 1 year as covariate revealed the most significant factors affecting GFR at year 5 were 1-year GFR, donor age > 60 years, and CsA-ME dose at 1 year. Risk factors associated with reduction in 5-year GFR (<65 mL/min) included donor or recipient age >60 years, delayed graft function, cadaveric donor, previous graft, and acute rejection. CsA-ME dose <3 mg/kg/d was found to protect GFR. Analysis of GFR at each year posttransplantation (Wilcoxon model) found 1-year CsA-ME (cutoff 3 mg/kg/d) had a significant effect at each time point. CONCLUSIONS: Compared to higher doses, CsA-ME <3 mg/kg/d at year 1 posttransplantation is associated with increased preservation of renal allograft function at year 5.

Chronic kidney disease is still present after renal transplantation with excellent function.

According to a k/DOQI work group, chronic kidney disease (CKD) can be present also in subjects with glomerular filtration rate (GFR) >90 mL/min or a serum creatinine (sCr) below 1.3 mg/dL. The aim of this study was to document the prevalence of clinical or biologic abnormalities among 190 cadaveric renal transplant patients with excellent and stable renal function at 6 months after transplantation as well as 5 years later. The recipients were 82 women and 108 men of mean age at transplantation of 44.56 +/- 11.73 years. All patients were on Neoral-based immunosuppression with at least 5-year follow-up. Mean sCr was 1.18 +/- 0.2 mg/dL. Mean GFR was 78.57 +/- 27.06 mL/min. Systolic blood pressure was >130 mm Hg in 56.6%, although 78.3% of patients were on antihypertensive therapy; 34.3% were anemic; 75.4% had serum cholesterol >200 mg/dL; 62.2% had serum triglyceride levels >170 mg/dL. Serum intact parathyroid hormone >100 pg/mL was observed in 38% of patients and 43% were on vitamin D supplementation, and 11.4% had developed posttransplant diabetes mellitus. With respect to controls, von Willebrand factor was higher in 81.2% (P < .0001; RR = 11); serum homocysteine levels in 75% (P < 0.001; RR = 7.61); PAI-1 in 37.5% (P = .0009; RR = 4). At 5 years posttransplantation we observed an overall improvement in these abnormalities. The vast majority of renal transplant patients with excellent graft function belong to stage 1 of CKD being affected by hypertension, dyslipidemia, anemia, and residual hyperparathyroidism. Markers of endothelial dysfunction were largely abnormal, a condition that could predispose to cardiovascular events.

Donor characteristics can influence transplant activities and the access to transplant for some age groups.

In recent years Italy has experienced a remarkable increase in organ donation and transplant rates for kidney transplantation. The organ donation rate has placed Italy among the European leaders, but a careful comparative evaluation of Italian and international registries data demonstrates that renal transplantations have not shared the same significant growth. In a decisive way donor characteristics have influenced not only the number of renal transplantations, but also the access to transplant for some age groups. We investigated the probability of transplantation from different age groups using the Kaplan-Meier method and the log-rank test. The 7-year probability of transplant was 72% for the 15 to 45 age group, 85.7% for the 46 to 55 age group, and 88.5% for the over 55 years group (P = .0029). Ethical considerations suggest new approaches of innovative promotion of living donor transplants and a revision of organ allocation criteria.

Venous thromboembolism in renal transplant recipients: high rate of recurrence.

Few data are available on the incidence of venous thromboembolism occurring in renal transplant recipients and optimal duration of oral anticoagulant therapy after thrombotic episode. Our study was performed to evaluate the risk of thrombosis recurrence in patients developing a first episode. Among 484 renal transplant patients 34 (7%) developed a first thromboembolism and were referred to the Thrombosis Centre: 28 patients (group 1) were prospectively studied, after stopping anticoagulants. Group 1 was compared with a group of 84 patients without an history of renal disease who had suffered from a first thrombotic episode and were matched for age, sex, and type of thrombotic event (group 2). During follow-up, 14/28 group 1 patients and 8/84 group 2 patients experienced thrombotic recurrence (P = .0001). Our data outline the high risk of recurrence in renal transplant recipients. Strategies for recurrence prevention are needed taking into account the high bleeding risk of anticoagulants in renal transplant patients.

Homocysteine-lowering therapy and carotid intima-media thickness in renal transplant recipients.

The aim of this study was to document, in hyperhomocysteinemic renal transplant recipients, the effect of vitamin supplementation on carotid intima-media thickness (cIMT). Fifty-six hyperhomocysteinemic stable renal transplant recipients were randomly assigned to either vitamin supplementation (group A) or placebo treatment (group B). All patients underwent high-resolution B mode ultrasound to measure IMT of common carotid arteries before and after 6 months of vitamin supplementation. In group A, cIMT significantly decreased after treatment, whereas no significant changes were observed in group B. In conclusion, our results demonstrate a beneficial effect of the treatment of hyperhomocysteinemia by vitamin supplementation on an early sign of atherosclerosis in a group of renal transplant recipients.

Immunosuppression in renal transplantation: viral diseases and chronic allograft nephropathy.

Chronic allograft dysfunction after renal transplantation can be ascribed to different causes, among which are viral infections. The aim of this work was to show the various ways by which different kinds of viruses affect transplant structure and function. Polyoma virus is an example of viruses directly affecting the kidney because of a specific tropism to the uroepitelial cells. Cytomegalovirus (CMV) has been chosen both because of the frequency of this infection and because CMV (as other viruses) can produce transplant vascular sclerosis. Finally, we describe hepatitis C virus (HCV) because of its capacity to induce renal lesions independently from chronic allograft nephropathy. Indeed HCV is likely to determine immunologically mediated nephritis in the transplanted kidney as well in the native one.

Efficacy and safety of Palmaz stent implantation in the treatment of renal artery stenosis in renal transplantation.

To verify the long-term efficacy and safety of Palmaz stent implantation in the treatment of transplant renal artery stenosis (TRAS), we reviewed the charts of 26 patients affected by TRAS and treated by percutaneous transluminal angioplasty (PTA) followed by permanent insertion of a Palmaz stent. The mean follow-up period was 43.31 +/- 33.6 months. The mean blood pressure fell significantly at 1 month after stenting (118 +/- 8.1 vs 101 +/- 7.8 mmHg; P < .0001); then remained stable. Renal artery blood flow, as determined by Doppler ultrasonography, was reduced from 352.5 +/- 56.5 to 157.3 +/- 53.7 cm/sec at 1 month after stenting (P < .0001). Renal function improved after stenting (serum creatinine 2.2 +/- 1.4 mg/dL preinsertion versus 1.72 +/- 1.05 at 3 years). In conclusion, in cases of severe or recurrent TRAS, stenting of the renal artery has proved to be an effective therapeutic tool. This method, which has low procedure costs and an extremely low complication rate has proved to be safe and to offer the potential of preserving luminal patency, improving the long-term efficacy of percutaneous angioplasty.

[Factors predicting outcome in renal transplantation]. / Fattori predittivi di outcome nel trapianto renale.

Organ shortage and necessity of good allocation to improve graft outcomes are well documented by epidemiological data. The authors analyze the main factors influencing long-term graft outcome concerning donor, peritransplant period and recipient. Donor age, marginal donors and new knowledges on donor brain death are the most relevant donor related factors. Cold ischemia is still a relevant peritransplant factor. Its influence on dentritic cell activation has been recently discovered. Regarding histocompatibility the six antigen match condition undoubtedly is associated to a better outcome. Most relevant recipient factors are: Preemptive transplant from living and deceased donors, whenever possible. With improvements in long-term kidney graft survival,the recurrence of original kidney disease is becoming an important cause of late graft failure. Recently several biological markers are emerging as graft outcome predictors. Recent findings indicate that certain cytokines or special lymphocyte subsets (alloreactive T memory cells) in the recipient could be powerful markers in the next future.

Descripción de dos casos de babesiosis cerebral en terneros de hasta 15 días de edad / Description of two cases of cerebral babesiosis in calves up to 15 days of age

Resumen La babesiosis es una enfermedad causada por Babesia bovis y Babesia bigemina, integrante del complejo conocido como "Tristeza bovina" y relevante en el Noroeste argentino (NOA). La presentación clínica de esta enfermedad es infrecuente en bovinos jóvenes, a los que se considera parcialmente resistentes a la babesiosis. Este trabajo describe dos casos de babesiosis cerebral en terneros de dos rodeos de cría diferentes, que a la necropsia mostraron ictericia, esplenomegalia y severa congestión cerebral y hemoglobinuria. Estructuras intraeritrocitarias compatibles morfológicamente con B. bovis fueron identificadas en extendidos de sistema nervioso central y sangre periférica teñidos con Giemsa y se confirmó luego la infección por medio de técnicas moleculares. La evaluación del estatus epidemiológico en los rodeos de origen determinó diferentes contextos: uno de los casos fue aislado en un rodeo con estabilidad enzoótica para babesiosis, donde la enfermedad clínica era escasa a pesar de altas tasas de transmisión de B. bovis; el segundo caso ocurrió en un rodeo en situación de brote con niveles significativos de mortandad. La ocurrencia de babesiosis (B. bovis) no había sido descripta todavía en terneros de la Argentina, sumándose ahora al diagnóstico diferencial para esta categoría de bovinos en zonas donde la enfermedad es enzoótica.

Abstract Bovine babesiosis is a disease caused by Babesia bovis and Babesia bigemina, as part of the tick fever complex and relevant in the Northwest of Argentina. Clinical occurrence of this illness is uncommon in young cattle, considered resistant to babesiosis. This work described two cases of cerebral babesiosis in calves of different beef herds. Jaundice, splenomegaly, severe cerebral congestion and hemoglobinuria was observed at necropsy. Babesia bovis-like structures were identified in cerebral and blood smears Giemsa stained and confirmed by molecular techniques. Different situations were recognized following the evaluation of the epidemiological status of both herds: the first one was a single case in a herd with enzootic stability for babesiosis, with scarce clinical cases despite high rates of B. bovis transmission; the other case was in a context of outbreak with high level of mortality within a herd susceptible to babesiosis. Clinical babesiosis was not previously described in calves from Argentina. Babesiosis must be taken into account for the differential diagnosis in calves from endemic areas of the disease.

High cysteine levels in renal transplant recipients: relationship with hyperhomocysteinemia and 5,10-MTHFR polymorphism.

BACKGROUND: Long-term survival of renal transplant recipients seems to be influenced by the occurrence of thromboembolic complications and cardiovascular disease. Preliminary data available in the literature found high levels of cysteine (Cy) as a risk factor for deep venous thrombosis independently of high homocysteine (tHcy) levels, but no data are available about Cy levels in renal transplant recipients. METHODS: To investigate Cy, tHcy, and plasminogen activator inhibitor-1 (PAI-1) levels and the prevalence of 5,10-methylenetetrahydrofolate reductase (MTHFR) in renal transplantation, we studied 70 stable renal transplant recipients and 66 age- and sex-matched normal subjects as controls. RESULTS: Cy, tHcy, and PAI-1 levels were significantly higher in renal transplant recipients with respect to controls (Cy: 254 micromol/L [117-466] vs. 198 micromol/L [99-331], P<0.001; tHcy: 17.0 micromol/L [4.0-68] vs. 8.1 micromol/L [2.0-24.0], P<0.00001; PAI-1: 16.8 IU/ml [5.1-45.5] vs. 7.9 IU/ml [4.0-18.0], P<0.00001). High Cy levels were detected in 35.8% of patients. Hyperhomocysteinemia, both in the fasting state and postmethionine loading test, was diagnosed in 90% of cases. The odds ratios for Cy and tHcy levels within the fourth quartile with respect to the other quartiles were markedly increased in renal transplant recipients even after adjustment for prevalent cardiovascular risk factors, glomerular filtration rate, tHcy and, Cy, respectively (Cy: 29.0 micromol/L [95% CI 7.0-111]; tHcy: 29.9 micromol/L [95% CI 7.5-118.1]). Fasting tHcy levels correlated well with PAI-1 (r=0.65; P<0.0001) but not with Cy levels (r=0.10; P=0.4). The prevalence of the MTHFR 677TT genotype in renal transplant recipients was not significantly higher in patients than in controls (mutant allele frequency: 0.48 in patients and 0.47 in controls) and was associated with significantly higher fasting and postmethionine tHcy levels both in controls and patients. After 2 months of vitamin supplementation, tHcy (Pre: 17.0 micromol/L [4.0-68]; Post: 7.5 micromol/L [2.3-21.9]; P<0.0001) and PAI-1 levels (Pre: 16.8 IU/ml [5.1-45.5]; Post: 10 IU/ml [2.0-25]; P<0.001) were significantly decreased, whereas Cy levels showed a small decrease that did not reach statistical significance (Pre: 254 micromol/L [117-466]; Post: 209 micromol/L [168-300]; P=0.3). Patients with the MTHFR 677TT genotype had the major percentage of decrease of tHcy levels with respect to the other genotypes. CONCLUSION: In conclusion, this study demonstrates the presence of elevated Cy plasma levels in renal transplant recipients. Vitamin supplementation reduces tHcy but not Cy levels, and the amount of decrease seems to be influenced by the MTHFR genotype.

Nanocrystals of magnesium and fluoride substituted hydroxyapatite.

Hydroxyapatite nanocrystals synthetized in the presence of different concentrations of magnesium and fluoride ions in solutions--1, 5 and 10 at.% have been submitted to a structural and chemical characterization. The syntheses were carried out in the presence of low molecular weight polyacrylic acid, which has been verified to inhibit hydroxyapatite crystallization. The polyelectrolyte is adsorbed into the crystals during the synthesis and provokes a reduction of the mean crystal sizes. The reduction is greater along the direction orthogonal to the c-axis, suggesting a preferential adsorption of the polyelectrolyte on the crystalline faces parallel to the c-axis. Both magnesium and fluoride can be incorporated into the hydroxyapatite structure. On the basis of the values of the lattice constants and of the magnesium relative content of the solid phase, it can be suggested that probably just a part of magnesium is substituted for calcium, the remainder being adsorbed on the crystal surface. However, magnesium destabilizes the apatitic structure favouring its thermal conversion into beta-tricalcium phosphate, and displays an inhibiting effect on the crystallization of hydroxyapatite. This last effect is enhanced by the simultaneous presence of polyacrylic acid. Fluoride substitution for hydroxyl ions into hydroxyapatite structure induces a slight increase of the crystal sizes along the c-axis direction. The data indicate that the experimental approach can be successfully used to prepare nanoapatite with crystallinity, crystal dimensions, composition, structure and stability very close to those characteristics of biological apatites.

Aplastic anemia due to B19 parvovirus infection in cadaveric renal transplant recipients: an underestimated infectious disease in the immunocompromised host.

Parvovirus B19 has been identified as the etiological agent of "fifth disease" in childhood. It is also a rarely reported cause of anemia in transplanted patients. During a period of 18 months we observed four cases (2 male and 2 female; 53 +/- 4.24 years) of severe aplastic anemia due to parvovirus B19 in kidney transplant patients. The overall incidence of the disease was 6.3% of all our transplanted patients. Symptoms of the disease occurred 22.5 +/- 9.75 days post-operatively. Serum creatinine was 1.5 +/- 0.35 mg/dl. Hb was 6.58 +/- 0.6 g/dl. All patients recovered with 15 days of high doses of commercial immunoglobulins. We conclude that B19 parvovirus infection is probably an underestimated disease in transplant patients. It is a first-period infection, probably donor-transmitted. High dose immunoglobulins are an effective but costly therapy.