[Application and effects of blood flow restriction training]. / Anwendung und Effekte des "blood flow restriction training".

Blood flow restriction (BFR) limits arterial and venous blood flow and leads to blood pooling, which could increase exercise-induced training effects. Strength training at lower intensities (20-30% of maximum strength) in combination with BFR showed similar effects on muscle hypertrophy as training with 70% without BFR. Low-intensity cycling endurance training with BFR improves muscle hypertrophy and endurance performance and activates angiogenesis. After determination of the complete occlusion pressure on the corresponding extremity, it is recommended that BFR training should be performed with 40-80% of the measured occlusion pressure. During strength training of the upper extremities, an occlusion of 60-80% leads to a reduction in the arterial blood flow by 20-50%. Local ischemia and hypoxia, a stronger metabolic stimulus, swelling of the muscle cells and the increased oxidative stress are discussed as causes for the increased training effects due to BFR. In short-term studies, comparable adjustments to parameters of fibrinolytic activity, coagulation and inflammation could be observed for strength training with and without BFR. So far, thromboses after BFR have been described only rarely but need to be further clarified by appropriate studies. The BFR training leads to a stronger activation of the muscular metabolic reflex and thus to a relatively greater increase in exercise blood pressure, so that cardiovascular parameters should be controlled during BFR training. First meta-analyses with small numbers of healthy people and patients indicate the effectiveness of BFR training. Standardization or guidelines for clinical use are still lacking.

Enhancing sensorimotor BCI performance with assistive afferent activity: An online evaluation.

An important goal in Brain-Computer Interfacing (BCI) is to find and enhance procedural strategies for users for whom BCI control is not sufficiently accurate. To address this challenge, we conducted offline analyses and online experiments to test whether the classification of different types of motor imagery could be improved when the training of the classifier was performed on the data obtained with the assistive muscular stimulation below the motor threshold. 10 healthy participants underwent three different types of experimental conditions: a) Motor imagery (MI) of hands and feet b) sensory threshold neuromuscular electrical stimulation (STM) of hands and feet while resting and c) sensory threshold neuromuscular electrical stimulation during performance of motor imagery (BOTH). Also, another group of 10 participants underwent conditions a) and c). Then, online experiments with 15 users were performed. These subjects received neurofeedback during MI using classifiers calibrated either on MI or BOTH data recorded in the same experiment. Offline analyses showed that decoding MI alone using a classifier based on BOTH resulted in a better BCI accuracy compared to using a classifier based on MI alone. Online experiments confirmed accuracy improvement of MI alone being decoded with the classifier trained on BOTH data. In addition, we observed that the performance in MI condition could be predicted on the basis of a more pronounced connectivity within sensorimotor areas in the frequency bands providing the best performance in BOTH. These finding might offer a new avenue for training SMR-based BCI systems particularly for users having difficulties to achieve efficient BCI control. It might also be an alternative strategy for users who cannot perform real movements but still have remaining afferent pathways (e.g., ALS and stroke patients).

Branched-chain amino acid catabolism rather than amino acids plasma concentrations is associated with diet-induced changes in insulin resistance in overweight to obese individuals.

BACKGROUND & AIMS: 3-Hydroxyisobutyrate (3-HIB), a catabolic intermediate of the BCAA valine, which stimulates muscle fatty acid uptake, has been implicated in the pathogenesis of insulin resistance. We tested the hypothesis that circulating 3-HIB herald insulin resistance and that metabolic improvement with weight loss are related to changes in BCAAs and 3-HIB. METHODS AND RESULTS: We analyzed plasma and urine in 109 overweight to obese individuals before and after six months on hypocaloric diets reduced in either carbohydrates or fat. We calculated the homeostasis model assessment index (HOMA-IR) and whole body insulin sensitivity from oral glucose tolerance tests and measured intramyocellular fat by magnetic resonance spectroscopy. BCAAs and 3-HIB plasma concentrations were inversely related to insulin sensitivity but not to intramyocellular fat content at baseline. With 7.4 ± 4.5% weight loss mean BCAA and 3-HIB plasma concentrations did not change, irrespective of dietary macronutrient content. Individual changes in 3-HIB with 6-month diet but not BCAAs were correlated to the change in whole body insulin sensitivity and HOMA-IR independently of BMI changes. CONCLUSIONS: 3-HIB relates to insulin sensitivity but is not associated with intramyocellular fat content in overweight to obese individuals. Moreover, changes in 3-HIB rather than changes in BCAAs are associated with metabolic improvements with weight loss. Registration number for clinical trials: ClinicalTrials.gov Identifier: NCT00956566.

Branched-chain and aromatic amino acids, insulin resistance and liver specific ectopic fat storage in overweight to obese subjects.

BACKGROUND & AIMS: Amino acids may interfere with insulin action, particularly in obese individuals. We hypothesized that increased circulating branched-chain and aromatic amino acids herald insulin resistance and ectopic fat storage, particularly hepatic fat accumulation. METHODS AND RESULTS: We measured fasting branched-chain and aromatic amino acids (tryptophan, tyrosine, and phenylalanine) by mass spectrometry in 111 overweight to obese subjects. We applied abdominal magnetic resonance imaging and spectroscopy to assess adipose tissue distribution and ectopic fat storage, respectively. Plasma branched-chain amino acids concentrations were related to insulin sensitivity and intrahepatic fat independent from adiposity, age and gender, but not to abdominal adipose tissue or intramyocellular fat. CONCLUSIONS: In weight stable overweight and obese individuals, branched-chain amino acid concentrations are specifically associated with hepatic fat storage and insulin resistance.

Comparison of 68Ga-DOTATOC biodistribution in patients with and without spleenectomy.

AIM: Ga-68 labeled somatostatin analogues such as 68Ga-DOTA0-Phe1-Tyr3-octrotide (DOTATOC) as PET tracers, have significantly improved the imaging of somatostatin receptors (SSTRs) expressing tumors. Due to unspecific parenchymal binding and the expression of SSTRs on leukocytes in the spleen this is the organ with the highest non-tumor uptake of DOTATOC. Therefore, we investigated the potential changes of normal tissue distribution and tumor concentration in patients with neuroendocrine tumors (NETs) with or without spleenectomy. METHODS: Out of 420 patients with pancreatic NET undergoing 68GA-DOTATOC PET/CT eleven patients with and eleven patients without spleenectomy were derived and matched in regard to tumor histology, tumor load, age and gender. The SUV(max) of liver metastases as well as of the following normal tissues was determined: pituitary gland, thyroid gland, liver parenchyma, kidneys and suprarenal glands. RESULTS: SUV(max) values with and without spleenectomy were: in the liver metastasis (19.17 ± 6.05 versus 37.67 ± 16.31), in the thyroid gland (2.56 ± 1.33 versus 2.66 ± 0.94), in the pituitary gland (4.08 ± 1.79 versus 4.92 ± 1.93) in suprarenal glands (7.18 ± 3.33 versus 9.73 ± 3.46 on the left side and 7.32 ± 3.03 versus 11.19 ± 5.72 on the right side), in the kidneys (8.1 3 ± 4.26 on the left side and 8.11 ± 4.16 on the right side versus 8.62 ± 2.17 on the left side and 9.79 ± 2.18 on the right side) and in normal liver tissue (5.74 ± 1.55 versus 6.22 ± 1.95). The difference was statistically significant (Wilcoxon test P<0.05) in tumor lesions, adrenal and kidney tissue. CONCLUSION: Spleenectomy must be considered as a relevant factor when reporting the outcome of SSTR targeted diagnostics and therapies.

Comparison of itraconazole, voriconazole, and posaconazole as oral antifungal prophylaxis in pediatric patients following allogeneic hematopoietic stem cell transplantation.

Oral antifungal prophylaxis with extended-spectra azoles is widely used in pediatric patients after allogeneic hematopoietic stem cell transplantation (HSCT), while controlled studies for oral antifungal prophylaxis after bone marrow transplantation in children are not available. This survey analyzed patients who had received either itraconazole, voriconazole, or posaconazole. We focused on the safety, feasibility, and initial data of efficacy in a cohort of pediatric patients and adolescents after high-dose chemotherapy and HSCT. Fifty consecutive pediatric patients received itraconazole, 50 received voriconazole, and 50 pediatric patients received posaconazole after HSCT as oral antifungal prophylaxis. The observation period lasted from the start of oral prophylactic treatment with itraconazole, voriconazole, or posaconazole until two weeks after terminating the oral antifungal prophylaxis. No incidences of proven or probable invasive mycosis were observed during itraconazole, voriconazole, or posaconazole treatment. A total of five possible invasive fungal infections occurred, two in the itraconazole group (4%) and three in the voriconazole group (6%). The percentage of patients with adverse events potentially related to clinical drugs were 14% in the voriconazole group, 12% in the itraconazole group, and 8% in the posaconazole group. Itraconazole, voriconazole, and posaconazole showed comparable efficacy as antifungal prophylaxis in pediatric patients after allogeneic HSCT.

PET imaging with a [68Ga]gallium-labelled PSMA ligand for the diagnosis of prostate cancer: biodistribution in humans and first evaluation of tumour lesions.

PURPOSE: Prostate-specific membrane antigen (PSMA) is a cell surface protein with high expression in prostate carcinoma (PC) cells. Recently, procedures have been developed to label PSMA ligands with (68)Ga, (99m)Tc and (123/124/131)I. Our initial experience with Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)]((68)Ga-PSMA) suggests that this novel tracer can detect PC relapses and metastases with high contrast. The aim of this study was to investigate its biodistribution in normal tissues and tumour lesions. METHODS: A total of 37 patients with PC and rising prostate-specific antigen (PSA) levels were subjected to (68)Ga-PSMA positron emission tomography (PET)/CT. Quantitative assessment of tracer uptake was performed 1 and 3 h post-injection (p.i.) by analysis of mean and maximum standardized uptake values (SUVmean/max) of several organs and 65 tumour lesions. Subsequently, tumour to background ratios were calculated. RESULTS: The PET/CT images showed intense tracer uptake in both kidneys and salivary glands. Moderate uptake was seen in lacrimal glands, liver, spleen and in small and large bowel. Quantitative assessment revealed excellent contrast between tumour lesions and most normal tissues. Of 37 patients, 31 (83.8 %) showed at least one lesion suspicious for cancer at a detection rate of 60 % at PSA <2.2 ng/ml and 100 % at PSA >2.2 ng/ml. Median tumour to background ratios were 18.8 (2.4-158.3) in early images and 28.3 (2.9-224.0) in late images. CONCLUSION: The biodistribution of the novel (68)Ga-PSMA tracer and its ability to detect PC lesions was analysed in 37 patients. Within healthy organs, kidneys and salivary glands demonstrated the highest radiotracer uptake. Lesions suspicious for PC presented with excellent contrast as early as 1 h p.i. with high detection rates even at low PSA levels.

[Radiologic and nuclear medicine diagnosis and therapy of thyroid disorders: Part II: Malignant thyroid diseases]. / Radiologische und nuklearmedizinische Diagnostik und Therapie der Schilddrüsenerkrankungen : Teil II: Maligne Erkrankungen der Schilddrüse.

Malignant thyroid diseases have increased in recent years. The distinction between differentiated and non-differentiated thyroid carcinoma is essential for therapy and follow-up. The frequently diagnosed papillary and follicular thyroid carcinomas are differentiated and have a good prognosis. Clinical symptoms are relatively unspecific, however imaging and laboratory testing can often provide evidence for diagnosis of thyroid carcinoma. Therapy typically involves surgery, ablative radioiodine therapy and subsequent suppressive hormone substitution. The pillars of follow-up are diagnostic scintigraphy, sonography and laboratory tests. Redifferentiation or a change of the tracer can make dedifferentiated tumors again susceptible to nuclide therapy. New treatment options have become available with the introduction of tyrosine kinase inhibitors.

[Radiologic and nuclear medicine diagnosis and therapy of thyroid disorders. Part 1: Benign thyroid diseases]. / Nuklearmedizinische und radiologische Diagnostik und Therapie der Schilddrüsenerkrankungen. Teil 1: Benigne Erkrankungen der Schilddrüse.

The thyroid gland is one of the most important endocrine organs. It has multiple influences on physical and mental health. The most important benign diseases are goiter, thyroid adenomas and inflammation. The clinical, imaging and laboratory findings are often pathognomic. The therapy spectrum ranges from follow-up, to medication or definitive therapy by operation or radioiodine therapy.

Thiazolidinedione response in familial lipodystrophy patients with LMNA mutations: a case series.

Type 2 familial partial lipodystrophy (FPLD2) patients show impaired glucose and lipid metabolism resulting from lipodystrophic 'lipid pressure' and an intrinsic defect in skeletal muscle metabolism. Since mutated lamin A may interfere with peroxisome proliferator activator gamma (PPARγ) expression, we hypothesized that PPARγ stimulation improves fat distribution and metabolic abnormalities in these patients. 5 nondiabetic FPLD2 patients were treated with rosiglitazone over 12 months. We assessed body composition, body fat distribution, and skinfold thickness/subcutaneous tissue thickness. We also determined venous glucose, insulin, and free fatty acid (FFA) concentrations, and respiratory quotient (RQ) before and during oral glucose tolerance testing. Adipose tissue and muscle fasting and postprandial metabolism were studied by microdialysis. Within 12 months treatment, hip circumference increased from 93.6±2.78 cm to 96.2±2.3 cm (p<0.05). Rosiglitazone reduced fasting glucose levels and liver transaminases. Baseline and postprandial FFA concentrations were significantly lower after 12 months treatment. RQ and muscle interstitial pyruvate and lactate did not respond to treatment. We conclude that PPARγ stimulation with rosiglitazone modestly improves glucose metabolism in FPLD2 patients presumably through proximal adipose tissue expansion. The intrinsic muscular metabolic defect does not respond to rosiglitazone.

Variations in truncal body circumferences affect fat mass quantification with bioimpedance analysis.

OBJECTIVE: To test the hypothesis that variations in trunk circumferences influence the accuracy of bioimpedance analysis (BIA) for assessment of percent fat mass (%FM). SUBJECTS AND METHODS: %FM was predicted with BIA, and compared with air-displacement plethysmography (ADP) in a small sample of 35 overweight (OW), 21 normal weight and 8 underweight volunteers. Waist and hip circumferences were assessed, and 15 of the OW subjects were measured before and after weight reduction. RESULTS: BIA and ADP provided similar cross-sectional estimates of group mean %FM (28.9±10.0 and 31.3±13.0%, respectively). However, within individuals, there were large between-method differences (Diff(BIA-ADP)) ranging from -13 to +13 %FM. Furthermore, we found a systematic bias of BIA related to the degree of adiposity. Consequently, %FM and fat mass loss during weight reduction in OW were underestimated with BIA when compared with ADP. Waist and hip circumferences were inversely associated with resistance (R) and reactance (P<0.01), and with Diff(BIA-ADP) (P<0.001). In women, the variability in hip circumference explained 76%, and in men, the variability in waist circumference explained 59% of Diff(BIA-ADP). CONCLUSION: Resistance changes associated with variations in trunk circumferences decrease resistance, and therefore impair the accuracy of BIA to assess %FM.

Neurohumoral and metabolic response to exercise in water.

Atrial natriuretic peptide (ANP) stimulates lipid mobilization and lipid oxidation in humans. The mechanism appears to promote lipid mobilization during exercise. We tested the hypothesis that water immersion augments exercise-induced ANP release and that the change in ANP availability is associated with increased lipid mobilization and lipid oxidation. In an open randomized and cross-over fashion we studied 17 men (age 31+/-3.6 years; body mass index 24+/-1.7 kg/m(2); body fat 17+/-6.7%) on no medication. Subjects underwent two incremental exercise tests on a bicycle ergometer. One test was conducted on land and the other test during immersion in water up to the xiphoid process. In a subset (n=7), we obtained electromyography recordings in the left leg. We monitored gas exchange, blood pressure, and heart rate. In addition, we obtained blood samples towards the end of each exercise step to determine ANP, norepinephrine, epinephrine, lactate, free fatty acids, insulin, and glucose concentrations. Heart rate, systolic blood pressure, and oxygen consumption at the anaerobic threshold and during peak exercise were similar on land and with exercise in water. The respiratory quotient was mildly reduced when subjects exercised in water. Glucose and lactate measurements were decreased whereas free fatty acid concentrations were increased with exercise in water. Water immersion attenuated epinephrine and norepinephrine and augmented ANP release during exercise. Even though water immersion blunts exercise-induced sympathoadrenal activation, lipid mobilization and lipid oxidation rate are maintained or even improved. The response may be explained by augmented ANP release.

Determinants of exercise-induced fat oxidation in obese women and men.

Endurance training at an intensity eliciting maximal fat oxidation may have a beneficial effect on body weight and glucose metabolism in obese patients. However, the exercise intensity at which maximal fat oxidation occurs and the factors limiting fat oxidation are not well studied in this population. Obese, otherwise healthy men (n=38) and women (n=91) performed an incremental exercise test up to exhaustion on a cycle ergometer. Substrate oxidation was estimated using indirect calorimetry. Magnetic resonance tomography and spectroscopy were conducted to assess body fat distribution and intramyocellular fat content. We determined the exercise intensity at which maximal body fat oxidation occurs and assessed whether body composition, body fat distribution, intramyocellular fat content, or oxidative capacity predict exercise-induced fat oxidation. Maximal exercise-induced fat oxidation was 0.30+/-0.02 g/min in men and 0.23+/-0.01 g/min in women (p<0.05). Exercise intensity at the maximum fat oxidation was 42+/-2.2% VO (2 max) in men and 43+/-1.7% VO (2 max) in women. With multivariate analysis, exercise-induced fat oxidation was related to fat-free mass, percent fat mass, and oxidative capacity, but not to absolute fat mass, visceral fat, or intramyocellular fat content. We conclude that in obese subjects the capacity to oxidize fat during exercise appears to be limited by skeletal muscle mass and oxidative capacity rather than the availability of visceral or intramyocellular fat.

Comparison of 68Ga-DOTATOC PET and 111In-DTPAOC (Octreoscan) SPECT in patients with neuroendocrine tumours.

PURPOSE: Neuroendocrine tumours (NETs) can be imaged with scintigraphy using radiolabelled somatostatin analogues. The aim of our study was to compare the value of (68)Ga-DOTATOC PET and (111)In-DTPAOC SPECT (Octreoscan) in the detection of NET manifestations. METHODS: Twenty-seven NET patients were prospectively examined. (68)Ga-DOTATOC PET and (111)In-DTPAOC SPECT were performed using standard techniques. Treatment was not applied in between. Mean and maximum standardised uptake values (SUVs) were calculated for PET findings. Tumour/non-tumour ratios were calculated for SPECT findings. Findings were compared by a region-by-region analysis and verified with histopathology, CT and MRI within 21 days. RESULTS: SUVs of positive lesions on (68)Ga-DOTATOC PET ranged from 0.7 to 29.3 (mean SUV) and from 0.9 to 34.4 (maximum SUV). Tumour/non-tumour ratios on (111)In-DTPAOC SPECT ranged from 1.8 to 7.3. In imaging lung and skeletal manifestations, (68)Ga-DOTATOC PET was more efficient than (111)In-DTPAOC SPECT. All discrepant lung findings and 77.8% of discrepant osseous findings were verified as true positive PET interpretations. In regional comparison of liver and brain, (68)Ga-DOTATOC PET and (111)In-DTPAOC SPECT were identical. In lymph nodes, the pancreas and the gastro-intestinal system, different values of the two techniques were not indicated in regional analyses. In a single patient, surgical interventions were changed on the basis of (68)Ga-DOTATOC PET findings. CONCLUSION: (68)Ga-DOTATOC PET is superior to (111)In-DTPAOC SPECT in the detection of NET manifestations in the lung and skeleton and similar for the detection of NET manifestations in the liver and brain. (68)Ga-DOTATOC PET is advantageous in guiding the clinical management.

Exercise renography in essential hypertension.

Exercise renography is an investigative procedure used to visualize a renal functional disturbance of essential hypertension (EH). The exercise protocol was developed to intensify a renal functional abnormality observed in standing hypertensive patients, when it appeared that this disturbance was directly associated with EH. Clearance determinations during light ergometric exercise showed that the abnormal scintigraphic images of the exercise renogram result from a prominent contraction of glomerular filtration rate (GFR), while effective renal plasma flow (ERPF) remained comparatively stable. The results obtained at present with exercise renography and clearance determinations suggest that afferent-efferent glomerular vessel dysfunction disrupts the stable relationship between GFR and ERPF in EH. This relationship is severely disturbed, and most readily recognized, during exercise. It is suspected that this functional abnormality results in the activation of the renin-angiotensin axis. A particularly exciting consequence of this research is the recognition that scintigraphy permits recognition of a disruption of the stable relationship of GFR and ERPF. This opens the door to a broad area of research unrelated to EH, since initial results in renovascular disease and urinary tract obstruction indicate that the fixed relationship between GFR and ERPF can be disturbed in these and other diseases as well.

Afferent-efferent vessel dysfunction appears to be a specific characteristic of a large subset of patients with essential hypertension.

Exercise renography makes it possible to subdivide essential hypertensives (EHs) into two distinct populations. Fifty to 60% develop exercise-mediated renal dysfunction and a transitory, severe reduction of glomerular filtration. The other subset of EHs does not have exercise-mediated renal dysfunction. We hoped to learn whether the disturbance is also present while EHs rest. Twenty-six EHs and 21 normotensive controls were studied with a resting sequential renogram using Tc-99m-mercaptoacetyl-triglycine (MAG3), a tracer excreted primarily by proximal tubular cells. EHs also had an exercise renogram. All persons had three consecutive 10-min dual-tracer infusion clearance determinations with 111In-DTPA and 131I-hippurate, for the simultaneous determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). To demonstrate the accuracy of the clearance procedure we sought to reproduce Hollenberg's results which show greater flow variability in EH than in normotension. Following this, the variability (VAR) of the GFR and ERPF as well as the variability fraction (VF), the ratio of GFR variability divided into the ERPF variability, were calculated. Hollenberg's results were reproduced. Sixteen of 26 essential hypertensives developed exercise-mediated renal dysfunction. GFR-VAR in EH differed from controls. The VF suggests that EHs with a bilateral abnormal exercise renogram have a more pronounced GFR variability than those EH with a normal exercise renogram. The results point to intraglomerular pressure fluctuations in patients with EH, and the VF suggests that this may be more pronounced in EHs with a bilateral abnormal exercise renogram than in those with a normal exercise renogram. It is hypothesized that the variable GFR provokes renin secretion in EH.

[Nuclear medicine in kidney diagnosis]. / Nuklearmedizinische Nierendiagnostik.

A brief review of frequently requested examinations is presented. The clinical physiology associated with characteristic function images observed in obstruction, urinary leaks, hypertension, renal failure, and in renal transplantation are presented, as is the use of function images in the patient with renal malignancy.

[Impact of pretreatment variables on the outcome of standardized 131I therapy with 150 Gray in Graves' disease]. / Einfluss prätherapeutischer Variablen auf die Wirkung einer standardisierten 131J-Therapie mit 150 Gray beim Morbus Basedow.

AIM: We examined the impact of several pretreatment variables on thyroid size and function in 61 patients with Graves' disease one year after a standardized [131]I treatment with 150 Gray. METHODS: FT3, FT4, and TSH serum concentrations were determined before and 1.5, 3, 6, and 12 months after therapy. Thyroid size was measured by ultrasound and scintigraphy before and one year after therapy. RESULTS: One year after therapy, 30% of the patients had latent or manifest hyperthyroidism, 24% were euthyroid, and 46% had developed latent or manifest hypothyroidism. Age and initial thyroid volume were major predictors of post-therapeutical thyroid function. Thus, persistent hyperthyroidism was observed in 70% of the patients age 50 years and older with a thyroid size of more than 50 ml. With few exception, thyroid size markedly decreased after therapy. Initial thyroid size and age were also major predictors of posttherapeutical thyroid volume. Thyroid size normalized in all patients younger than 50 years of age, independent from initial thyroid size. CONCLUSION: Radioiodine treatment with 150 Gray causes a considerable decrease in thyroid size in most patients with Graves' disease. Age and initial thyroid volume are important determinants of thyroid function and size after therapy and should be considered in dose calculation.

[Dialysis-associated amyloidosis. Part 1: Biochemistry, clinical aspects, roentgen morphology]. / Dialyseassoziierte Amyloidose. Teil 1: Biochemie, Klinik, Röntgenmorphologie.

Dialysis-related amyloidosis is characterized clinically by the carpal tunnel syndrome, pain and swelling of joints. These alterations are due to amyloid deposits in the carpal tunnel, in the synovia, ligaments and bones. It has been shown that beta 2m is the major component of this amyloidosis. Serum and urine concentration of beta 2m are markedly elevated in chronic renal failure due to failure of filtration and lack of metabolism by the renal tubular epithelium. beta 2m-derived amyloid is identified by immunohistochemistry using antibodies derived against beta 2m. Radiology shows cyst-like periarticular bone defects, destructive arthropathy and spondylarthropathy.