On the gamma radiation response of commercially available 3D printing materials for medical dosimetry

3D printing technology has rapidly spread for decades, allowing the fabrication of medical implants and human phantoms and revolutionizing healthcare. The objective of this study is to evaluate some radiological properties of commercially available 3D printing materials as potential tissue mimicking materials. Among fifteen materials, we compared their properties with nine human tissues. In all materials and tissues, exposure and energy absorption buildup factors were calculated for photon energies between 0.015 and 15 MeV and penetration depths up to 40 mean free path. Furthermore, the Geant4 Monte Carlo toolkit (version 10.5) was used to simulate their percentage depth dose distributions. In addition, equivalent atomic numbers, effective atomic numbers, attenuation coefficients, and CT numbers have been examined. All parameters were considered in calculating the average relative error (σ), which was used as a statistical comparison tool. With σ between 6 and 7, we found that Polylactic Acid (PLA) was capable of simulating eye lenses, blood, soft tissue, lung, muscle, and brain tissues. Moreover, Polymethacrylic Acid (PMAA) material has a σ value of 4 when modeling adipose and breast tissues, respectively. Aside from that, variations in 3D printing materials' infilling percentage can affect their CT numbers. We therefore suggest the PLA for mimicking soft tissue, muscle, brain, eye lens, lung and blood tissues, with an infill of between 92.7 and 94.3 percent. We also suggest an 89 percent infill when simulating breast tissue. Furthermore, with a 96.7 percent infill, the PMAA faithfully replicates adipose tissue. Additionally, we found that a 59 percent infill of Fe-PLA material is comparable to cortical bone. Due to the benefits of creating individualized medical phantoms and equipment, the results might be seen as an added value for both patients and clinicians.

[Hemolytic and uremic syndrome and related thrombotic microangiopathies: Epidemiology, pathophysiology and clinics]

Thrombotic microangiopathies (TMA) represent an eclectic group of conditions, which share hemolytic anemia and thrombocytopenia as a common defining basis. Remarkable breakthroughs in the physiopathological setting have allowed for a thorough recomposition of the disparate syndromes, which form the constellation of TMA. In this view, clinicians now discriminate thrombocytopenic thrombotic purpura (TTP) defined by a severe deficiency in ADAMTS13, which is rarely associated with a severe renal involvement and the hemolytic and uremic syndrome (HUS) in which renal impairment is the most prominent clinical feature. HUS can result from toxins stemming from bacterial infections of the digestive tract, alternate complement pathway abnormalities, metabolic or coagulation disorders or, lastly, drug and various toxic compounds. The diverse forms of HUS reflect the insights gained in the understanding of the pathophysiological mechanisms underpinning TMA. In this first part, a broad overview of the epidemiological, physiopathological and clinical aspects of HUS and related TMA syndromes is presented.

[Retroperitoneal fibrosis in adults: Main characteristics and relevance of the diagnostic procedures based on a retrospective multicenter study on 77 cases]

INTRODUCTION

Retroperitoneal fibrosis (RPF) is a rare disorder characterized by the sheathing of retroperitoneal structures by fibro-inflammatory process. It can be either isolated or associated with an underlying disease or condition. In the absence of consistent and consensual approach, the objective of this study was to assess the relevance of diagnostic tests performed during the diagnostic work-up of RPF.

METHODS

Seventy-seven patients were included in this retrospective multicenter study. The diagnosis of RPF was defined by the presence of a thickened circumferential homogeneous tissue unsheathing the infrarenal aorta, excluding peri-aneurysmal fibrosis and a clear evidence of a cancer.

RESULTS

In 62 cases (80.5%), the RPF was considered as being primary or "idiopathic". Surgical (n=31) or CT-guided (n=9) biopsies of the RPF were performed in half of the patients showing some fibrotic or non-specific inflammatory lesions in 98% of cases. A bone marrow biopsy was performed in 23 patients leading to diagnosis of low grade B cell non-Hodgkin lymphoma in a single patient who also had a monoclonal gammopathy IgM. The systematic search for autoantibodies or serum tumor markers was of no diagnostic value.

CONCLUSIONS

Although the diagnostic procedure was heterogeneous, no cause or associated disease was found in the majority of cases of FRP in this series. In the absence of any clinical or paraclinical evidence suggesting an underlying disease or any atypical features at presentation, a number of non-invasive tests (autoantibodies, tumor markers, bone scintigraphy) and also more invasive diagnostic tests (bone marrow and RPF biopsies) seem of little relevance.

[Primary hepatic neuroendocrine carcinoma]

Primary neuroendocrine carcinoma of the liver is a rare tumour, probably arising from scattered neuroendocrine cells of the bile duct. We present the case of a 72-year-old male who experienced gradual weight loss and diarrhoea. Given the fact that he had stayed in the Dominican Republic, a parasitic disease was initially suspected. However, this was not confirmed. Further examination showed tumour infiltration of the liver. Fine needle aspiration cytology of the tumour site was performed. The diagnostic procedure revealed neuroendocrine carcinoma. The tumour cells expressed the following neuroendocrine markers (chromogranin, synaptophysin, CD56 and NSE) as well as the epithelial marker AE1-AE3. The tumour was considered metastasis of the primary tumour located in the gastrointestinal tract. A thorough clinical examination was performed including gastroscopy, colonoscopy, In-111 Octreoscan scintigraphy, computed tomography and magnetic resonance imaging. These methods revealed metastases in the vertebrae, pelvis, long bones and skull. No other tumour sites were found in the lungs, gastrointestinal tract or pancreas. The patient became increasingly cachexic and later died. An autopsy showed massive multicentric tumour infiltration of the liver. Histological examination revealed well differentiated neuroendocrine carcinoma which transformed into intermediate and small cells. The autopsy found no tumour sites in the gastrointestinal tract, lungs or pancreas. The results were suggestive of primary neuroendocrine carcinoma of the liver.

KEYWORDS

neuroendocrine carcinoma - liver - primary tumour.

[Atypical hemolytic-uremic syndrome related to abnormalities within the complement system]

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy (TMA) disorder characterised by the association of haemolytic anaemia, thrombocytopenia and acute renal failure. Atypical forms (non-shigatoxin related forms) may be familial or sporadic, frequently with relapses and most of them lead to end stage renal failure. During the last years, different groups have demonstrated genetic predisposition to atypical HUS (aHUS) involving five genes encoding for complement components which play a role in the activation or control of the alternative pathway: encoding factor H (CFH), accounting for 30% of aHUS; CD46 (encoding membrane cofactor protein [MCP]) accounting for approximately 10% of aHUS; CFI (encoding factor I) accounting for an estimated 5-15% of patients; C3 (encoding C3) accounting for approximately 10% of aHUS; and rarely CFB (encoding factor B). Predisposition to aHUS is inherited with incomplete penetrance. It is admitted that mutations confer a predisposition to develop aHUS rather than directly causing the disease and that a second event (genetic or environmental) is required for disease manifestation. HUS onset follows a triggering event in most cases (frequently banal seasonal infection and pregnancy). Uncontrolled C3 convertase leads to increased deposition of C3b on vascular endothelium and participates to the prothrombotic state. The phenotype of aHUS is variable ranging from mild forms, with complete recovery of renal function to severe forms with end stage renal disease within the first year after the onset. Overall, the outcome is severe with a mortality rate of 10% and with more than 60% of patients on dialysis. The most severe prognosis was in the CFH mutation group. There is a high risk of recurrence of the disease after renal transplantation in patients with mutations in CFH, CFI, CFB and C3. Plasma therapy may allow complete haematological remission but frequently with persistent renal damage. Some patients are plasma resistant and some are plasma dependent. The recent progress in the determination of the susceptibility factors for aHUS, have allowed to propose new diagnostic tests including a molecular genetic testing and may permit to consider some new specific treatments in this disease (human plasma-derived CFH or complement inhibitors).

Multiple OXPHOS deficiency in the liver of a patient with CblA methylmalonic aciduria sensitive to vitamin B(12)

An adult patient with methylmalonic aciduria due to defective cobalamin synthesis (CblA) responsive to vitamin B(12) presented suddenly with severe visual impairment ascribed to optic atrophy followed by a fatal multiorgan failure and lactic acidosis but low methylmalonic acid in plasma and urine. Multiple deficiency of oxidative phosphorylation was found in the patient's liver. We suggest that patients with B(12)-sensitive methylmalonic aciduria who have a milder clinical course should be carefully monitored for long-term complications.

Complement mutation-associated de novo thrombotic microangiopathy following kidney transplantation

Mutations in one or more genes encoding complement-regulatory proteins predispose to atypical hemolytic uremic syndrome (aHUS) and its recurrence following kidney transplantation. We evaluated plasma complement level and performed a screening for mutations in genes encoding complement Factors H and I (CFH, CFI) and membrane cofactor protein (MCP) in 24 kidney transplant recipients experiencing de novo thrombotic microangiopathy (TMA). Six patients presented with low C3 and/or low Factor B levels suggestive complement alternative pathway. A mutation in the CFH or CFI gene was found in 7/24 patients (29%), two of whom had a mutation in both genes. On the contrary, no mutation was identified in a control kidney transplant patients group (n = 25) without TMA. Patients with or without mutations were similar with regard to clinical features. Eight out of 24 patients lost their graft within 1 year of posttransplantation including six patients with a CFH mutation or a decrease of C3 or CFB in plasma. To conclude, kidney transplant patients with de novo TMA exhibit an unexpectedly high frequency of CFH and CFI mutations. These results suggest that genetic abnormalities may represent risk factors for de novo TMA after kidney transplantation and raise the question of the best therapeutic strategy.

Osteomalacia revealing celiac disease and primary biliary cirrhosis-related Fanconi syndrome in a patient with systemic sclerosis

Systemic sclerosis (SSc) may affect the gastrointestinal tract and cause very rarely malabsorption syndrome related to bacterial overgrowth. Malabsorption syndrome may be responsible for weight loss, diarrhea, osteomalacia, and iron and vitamins deficiency. We report the case of a SSc patient who developed osteomalacia caused by the combination of two exceptional conditions in the setting of SSc: celiac disease (CD) and primary biliary cirrhosis (PBC)-related Fanconi syndrome. Oral prednisone with angiotensin-converting enzyme inhibitors, was initiated because of active lesions of tubulitis, and led to the complete regression of bone pains, and by the improvement of renal function and regression of the features of proximal tubulopathy. Thus, in the presence of vitamin deficiencies in a patient with SSc, together with a search for malabsorption syndrome secondary to bacterial overgrowth, CD and/or PBC-associated Fanconi syndrome should be investigated.

[Progressive multifocal leukoencephalopathy in a non-AIDS patient: high efficiency of combined cytarabine and cidofovir]

INTRODUCTION

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system, occurring in immunocompromised patients. Treatment, not codified to date, is more often inefficient with a rapid and fatal deterioration.

CASE RECORD

A 48-year-old woman, treated with immunosuppressant agents for systemic lupus, presented with PML mimicking neurolupus flare. A complete remission was obtained with cytarabine and cidofovir.

CONCLUSION

Combined cytarabine and cidofovir appears a promising therapeutic option in PML associated with autoimmune systemic disorders.

[Intravenous immunoglobulins and acute renal failure: mechanism and prevention]

Acute renal failure (ARF) is a rare complication of the use of intravenous immunoglobulins (IVIg) with an estimated incidence lower than 1 %. It is related to acute tubulo-interstitial nephropathy due to to the occurrence of osmotic nephrosis mainly in the proximal tubule. The recovery of renal function usually occurs within ten days. The risk factors for the occurrence of ARF during the use of IVIg are: age > 65 years, preexisting renal failure (creatinine clearance < 60 ml/min), diabetes, dose, hypovolemia, the concomitant use of other nephro-toxic agents (contrast media agents, etc.). IVIg related ARF has been reported mainly with saccharose-containing IVIg but also with maltose and glucose-containing IVIg. However, no definite conclusion can be drawn concerning the role of the stabilising agent in the genesis of ARF due to the larger use of saccharose-containing IVIG compared to other IVIG and the absence of controlled trials comparing various types of IVIg. Clinicians must be aware that ARF may occur with all types of IVIg. In patients with at least one risk factor for ARF, diuretics should be discontinued, an hydration using saline solutions should be started and the concomitant administration of other nephrotoxic drugs be avoided. Clinicians should use the minimal required dose of IVIg and slow the flow of perfusion (1-2 ml/kg/h).

Nephrotic syndrome associated with hemophagocytic syndrome

Hemophagocytic syndrome (HPS) is defined by bone marrow and organ infiltration by activated, nonmalignant macrophages, which phagocytose blood cells. The clinical spectrum of HPS is broad, but renal involvement has rarely been investigated. We report a previously unknown renal manifestation of HPS: nephrotic syndrome. This multicentric retrospective study included patients fulfilling the following criteria: (i) no history of nephropathy; (ii) HPS diagnosis with histologic evidence of hemophagocytosis; (iii) occurrence of nephrotic syndrome during HPS; and (iv) available renal histology. Using the same criteria, we also searched the literature for additional cases. We identified nine patients retrospectively and found two additional cases in the literature (five males and six females, whose mean age was 34 +/- 27 years). Black African patients predominated (63.6%). HPS was due to lymphoma (six cases), infectious disease (three cases), and autoimmune disease (one case), and was primary in one patient. Acute renal failure was associated with nephrotic syndrome in 10/11 cases. Renal histology showed acute tubular necrosis associated with collapsing glomerulopathy in five patients (all Africans with negative human immunodeficiency virus serology), minimal change glomerulopathy in four, and thrombotic-microangiopathy with abnormal podocytes in two. Death occurred in seven cases. Nephrotic syndrome should be included among the renal complications of HPS with acute renal failure. We postulate that abnormal T-cell activation and/or high pro-inflammatory cytokine levels during HPS might cause podocyte injuries, especially among African patients with a susceptible genetic background.

La fuite urinaire d'érythropoïétine : une cause méconnue d'anémie au cours des syndromes néphrotiques

INTRODUCTION

Nephrotic syndrome (NS) is characterized by an excessive urinary protein excretion.

CASE RECORD

A woman, followed-up for NS, present progressive anemia, with no simple explanation. Plasma EPO is low with significant urinary EPO excretion. Treatment with EPO corrects hemoglobin level.

CONCLUSION

EPO deficiency due to excessive urinary excretion is an underestimated cause of anemia during NS.

Increase of circulating neutrophil and platelet microparticles during acute vasculitis and hemodialysis

Release of microparticles (MPs) from blood cells may occur upon various activation signals. MPs from neutrophil and platelet have been studied in systemic infectious diseases and cardiovascular diseases, respectively. They are here investigated in common nephropathies including vasculitis and dialysis, two conditions characterized by neutrophil activation. Flow cytometry analysis of neutrophil-derived (CD66b-positive) and platelet-derived (CD41a-positive) MPs was performed on 213 plasma samples from patients with various nephropathies, including 46 patients with vasculitis and 40 hemodialysis patients. MPs released ex vivo, during neutrophil activation in whole blood, were also measured in these patients. Correlations with clinical parameters and creatinine clearance were evaluated. The results show that MPs present in plasma from patients or healthy controls are from various origins: platelet-derived (38+/-22%), neutrophil-derived (2.8+/-3.8%) MPs, mixed aggregates of neutrophil/platelet MPs (28+/-15%) or neither from neutrophil or platelet (null) 31+/-20%. Acute vasculitis showed the highest level of all types of MPs, while other nephropathies did not result in significant changes of MP levels. A significant increase was observed during hemodialysis sessions. In patients with renal failure, no correlation was seen between MP levels and creatinine clearance. In conclusion, neutrophil and platelet MP levels are non-specific markers of neutrophil activation during vasculitis acute phase and dialysis-induced inflammation. Circulating aggregates of neutrophil/platelet MPs co-express adhesion molecules of both cell types and may be thus endowed with inflammation and coagulation- thus modulating properties.

Rituximab therapy for childhood-onset systemic lupus erythematosus

OBJECTIVE

To describe the safety and efficacy of rituximab in the treatment of childhood-onset systemic lupus erythematosus (SLE).

STUDY DESIGN

We conducted a French multicenter retrospective study of childhood-onset SLE treated with rituximab.

RESULTS

Eleven girls with severe SLE, including 8 girls with class IV or V lupus nephritis, 2 girls with severe autoimmune cytopenia, and 1 girl with antiprothrombin antibody with severe hemorrhage, were treated with rituximab. The mean age at onset of rituximab treatment was 13.9 years. Patients received 2 to 12 intravenous infusions of rituximab (350-450 mg/m2/infusion), with corticosteroids. Six patients also received different standard immunosuppressive agents, including Cyclophosphamide (2 patients). Remission was achieved in 6 of 8 patients with lupus nephritis and in the 2 patients with autoimmune cytopenia. Steroid therapy was tapered in 5 patients who responded to treatment, and low-dose prednisone treatment was maintained in 1 patient. The mean follow-up period was 13.2 months (range, 6-26 months), and remission lasted in all who patients who responded to treatment, except 1 patient who was successfully retreated with a second course of rituximab. Anti-double-stranded DNA antibody levels decreased in 6 of 11 patients, and anticardiolipin antibody levels decreased in 3 of 4 patients. Severe adverse events developed in 5 patients. Effective depletion of peripheral blood B cells was observed in 7 of 8 patients who were examined, and this paralleled the remission.

CONCLUSION

Rituximab may be an effective co-therapy; however, further investigations are required because severe adverse events occurred in 45% of the patients in this study.

[Progressive renal failure caused by lithium nephropathy]

OBJECTIVES

Study the renal consequences of lithium therapy and find out whether lithium-induced chronic renal toxicity can provoke a progressive nephropathy, leading to advanced renal failure, requiring periodical dialysis.

METHODS

Fifty-three patients treated with long-term lithium salts were included in the study. They had developed chronic renal failure (creatinine clearance inferior to 80 ml/min) not due to any other cause.

RESULTS

These patients had received lithium salts for a mean period of 17.7 years. The mean reduction in creatinine clearance was of 2.23 ml/min/year. Final clearance correlated negatively with the duration of lithium administration. In 7 patients treated a mean of 22 years, progression towards terminal kidney failure required periodical dialysis. Around 30% of patients exhibited mild hypercalcemia.

CONCLUSION

Lithium nephropathy inducing progressive renal failure is a reality. Its prevalence in patients treated long-term with lithium should be assessed.

Longer duration of predialysis nephrological care is associated with improved long-term survival of dialysis patients

BACKGROUND

Late nephrological referral of chronic renal failure patients has been shown to be associated with high morbidity and short-term mortality on dialysis. However, the impact of predialysis nephrological care duration (PNCD) on the long-term survival of dialysis patients had not been evaluated.

METHODS

We studied data from all 1057 consecutive patients who started dialysis treatment at the Necker Hospital from 1989 to 1998 (mean age at start of dialysis 53.8+/-17.2 years (range 18-91 years), excluding from analysis patients who presented with acute renal failure (n=60) or advanced malignancy (n=35). We evaluated the effects of PNCD and clinical risk factors on all-cause mortality after long-term follow-up on dialysis.

RESULTS

Among the 1057 patients analysed (13.2% diabetics), PNCD was <6 months in 258 patients, 6-35 months in 267 patients, 36-71 months in 227 patients and >or=72 months in 307 patients. Cardiovascular (CV) morbidity, namely a history of myocardial or cerebral infarction, peripheral arteriopathy, and/or cardiac failure, before starting dialysis was 39.6% and 37.4%, respectively, in patients followed for <6 months or 6-35 months, compared with 24.4% in those followed for 36-71 months and 19.9% in those followed for >or=72 months (P<0.001). Five-year survival was significantly lower in patients with a PNCD of <6 months (59+/-4.1%) than for 36-71 months or >or=72 months (77.1+/-3.7 and 73.3+/-3.6%, respectively, P<0.001), but similar to those followed for 6-35 months (65.3+/-3.9%, NS). By Cox proportional hazard analysis, PNCD <6 months, age, diabetes and prior CV disease were independent predictive factors of all-cause death on dialysis.

CONCLUSIONS

This study provides suggestive evidence that longer duration of regular nephrological care in the predialysis period, at least for several years prior to the start of dialysis, is associated with a better long-term survival on dialysis. Such data strongly support the argument for early referral and regular nephrological care of chronic renal failure patients.

Granulomatous renal disease in a patient with common variable immunodeficiency

Common variable immunodeficiency (CVID), the most common cause of primary hypogammaglobulinemia, is characterized by a decreased serum immunoglobulin level, recurrent infections, and the occurrence of various autoimmune diseases. Granulomatous disease has been reported previously in several patients with CVID, with granuloma occurring in the lymph nodes, spleen, liver, central nervous system, and bone marrow. We report the first published case of renal granulomatous disease in a CVID patient presenting with subacute renal failure. Renal function partially recovered after corticosteroid treatment and intravenous immunoglobulin infusions. The pathogenesis of granulomatous disease in CVID is unclear but may involve monocyte and T-cell abnormalities.

Presentation and revascularization outcomes in patients with radiation-induced renal artery stenosis

This study analyzed the initial presentation and revascularization outcomes of patients with radiation-induced renal artery stenosis, a rare complication of therapeutic irradiation. Of 11 patients with renal artery stenosis after irradiation, 7 patients fulfilled the following criteria: normotension before irradiation, radiation dose greater than 25 grays delivered to the renal arteries, associated perirenal radiation-induced lesions, and absence of arterial disease outside the radiation field. The median age at irradiation was 30 years, and the median local irradiation dose was 40 grays. The median time from irradiation to referral was 13 years. All patients were hypertensive at referral, with a median blood pressure (BP) of 171/102 mm Hg and median treatment score of two. The median glomerular filtration rate was 67 mL/min. Two patients had bilateral stenoses and 1 patient had stenosis affecting a single kidney. Stenoses were proximal in 6 patients and truncal in 1 patient, and all had the appearance of atherosclerotic stenosis. Percutaneous transluminal renal artery angioplasty (PTRA) was successful in 5 patients, but required multiple insufflations. PTRA failed in 1 patient, who subsequently underwent an aortorenal bypass. After a median follow-up of 36 months, 2 patients had died of noncardiovascular causes and 4 patients remained hypertensive, with a median BP of 136/85 mm Hg and median treatment score of two. No restenosis occurred, but aneurysms developed at the site of angioplasty in 1 patient. If hypertension occurs even decades after irradiation, a radiation-induced renal artery stenosis should be sought in patients who have undergone abdominal irradiation.

[Course of chronic renal failure epidemiology and prediction of maintenance dialysis needs in France]

Epidemiology of diseases leading to end-stage renal disease (ESRD) in France has greatly changed over the past decades, with the disappearance of type 1 primary membranoproliferative glomerulonephritis, and the increased incidence of both vascular and diabetic nephropathies. The incidence of ESRD is continuously growing, by about 4% per year, with a present rate of more than 100 new patients per million population (pmp) per year. The rise in incidence is mainly observed in older subjects. As a consequence, one may predict a relentless increase in the next years, in parallel with the relentless ageing of the population. The number of ESRD patients on maintenance dialysis is also growing, by nearly 4% per year. The present prevalence is 433 pmp in the Ile de France area, ranging from 268 pmp in subjects aged 15-59 years, to as high as 980 pmp in the population aged 60 years or more. Whereas the number of in-center treated patients has remained quite stable over the past five years, the total number and proportion of out-center treated patients is continuously increasing, as expected, thanks to the development of self-care hemodialysis and of peritoneal dialysis. These data may help predict logistic requirements for maintenance dialysis in the next years.