Beta-2-microglobulin and HLA-related glycoproteins in human urine and serum

Supersaturation, a Critical Factor Underlying Proteostasis of Amyloid Fibril Formation

From a physicochemical viewpoint, amyloid fibril formation is a phase transition from soluble to crystal-like sates limited by supersaturation. It occurs only above solubility (i.e., the solubility limit) coupled with a breakdown of supersaturation. Although many studies have examined the role of molecular chaperones in the context of proteostasis, the role of supersaturation has not been addressed. Moreover, although molecular chaperone-dependent disaggregations have been reported for preformed amyloid fibrils, amyloid fibrils will not dissolve above the solubility of monomers, even if agitations fragment long fibrils to shorter amyloid particles. On the other hand, on considering a reversible and coupled equilibrium of interactions, folding/unfolding and amyloid formation/disaggregation, molecules stabilizing native states can work as a disaggregase reversing the amyloid fibrils to monomers. It is likely that the proteostasis network has various intra- and extracellular components which disaggregate preformed amyloid fibrils as well as prevent amyloid formation. Further studies with a view of solubility and supersaturation will be essential for comprehensive understanding of proteostasis.

Association between serum β2-microglobulin levels and the risk of all-cause and cardiovascular disease mortality in chinese patients undergoing maintenance hemodialysis

BACKGROUND

The association between serum β₂-microglobulin (β₂M) levels and the risk of all-cause and cardiovascular disease (CVD) mortality and the incidence of cardiovascular events (CVEs) in patients undergoing maintenance hemodialysis (MHD) is inconclusive. Furthermore, no study has been performed in China on the significance of serum β₂M levels in MHD patients. Therefore, this study investigated the aforementioned association in MHD patients.

METHODS

In this prospective cohort study, 521 MHD patients were followed at Dalian Municipal Central Hospital affiliated with Dalian University of Technology from December 2019 to December 2021. The serum β₂M levels were categorized into three tertiles, and the lowest tertile served as the reference group. Survival curves were calculated by the Kaplan-Meier method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard models. Sensitivity analysis was performed by excluding patients with CVD at baseline.

RESULTS

During the follow-up period of 21.4 ± 6.3 months, there were 106 all-cause deaths, of which 68 were caused by CVD. When excluding CVD patients at baseline, there were 66 incident CVEs. Kaplan-Meier analysis revealed that the risk of all-cause and CVD mortality in the highest tertile of serum β₂M levels was significantly higher than that in the lowest tertile (P < 0.05), but not for the CVEs (P > 0.05). After adjusting for potential confounders, serum β₂M levels were positively associated with the risk of all-cause (HR = 2.24, 95% CI = 1.21-4.17) and CVD (HR = 2.54, 95% CI = 1.19-5.43) mortality, and a linear trend was evident (P < 0.05). Besides, the results of sensitivity analysis were consistent with the main findings. However, we didn't observed the significant association between serum β₂M levels and CVEs (P > 0.05).

CONCLUSION

The serum β₂M level may be a significant predictor of the risk of all-cause and CVD mortality in MHD patients. Further studies are needed to confirm this finding.

Macromolecular crowding and supersaturation protect hemodialysis patients from the onset of dialysis-related amyloidosis

Dialysis-related amyloidosis (DRA), a serious complication among long-term hemodialysis patients, is caused by amyloid fibrils of β2-microglobulin (β2m). Although high serum β2m levels and a long dialysis vintage are the primary and secondary risk factors for the onset of DRA, respectively, patients with these do not always develop DRA, indicating that there are additional risk factors. To clarify these unknown factors, we investigate the effects of human sera on β2m amyloid fibril formation, revealing that sera markedly inhibit amyloid fibril formation. Results from over 100 sera indicate that, although the inhibitory effects of sera deteriorate in long-term dialysis patients, they are ameliorated by maintenance dialysis treatments in the short term. Serum albumin prevents amyloid fibril formation based on macromolecular crowding effects, and decreased serum albumin concentration in dialysis patients is a tertiary risk factor for the onset of DRA. We construct a theoretical model assuming cumulative effects of the three risk factors, suggesting the importance of monitoring temporary and accumulated risks to prevent the development of amyloidosis, which occurs based on supersaturation-limited amyloid fibril formation in a crowded milieu.

Lifting the Veil: Characteristics, Clinical Significance, and Application of β-2-Microglobulin as Biomarkers and Its Detection with Biosensors

Because β-2-microglobulin (β₂M) is a surface protein that is present on most nucleated cells, it plays a key role in the human immune system and the kidney glomeruli to regulate homeostasis. The primary clinical significance of β₂M is in dialysis-related amyloidosis, a complication of end-stage renal disease caused by a gradual accumulation of β₂M in the blood. Therefore, the function of β₂M in kidney-related diseases has been extensively studied to evaluate its glomerular and tubular functions. Because increased β₂M shedding due to rapid cell turnover may indicate other underlying medical conditions, the possibility to use β₂M as a versatile biomarker rose in prominence across multiple disciplines for various applications. Therefore, this work has reviewed the recent use of β₂M to detect various diseases and its progress as a biomarker. While the use of state-of-the-art β₂M detection requires sophisticated tools, high maintenance, and labor cost, this work also has reported the use of biosensor to quantify β₂M over the past decade. It is hoped that a portable and highly efficient β₂M biosensor device will soon be incorporated in point-of-care testing to provide safe, rapid, and reliable test results.

Serum Beta-2 Microglobulin: A Possible Biomarker for Atrial Fibrillation

BACKGROUND Atrial fibrillation (AF) is the most common persistent arrhythmia that can cause complications (including stroke). Therefore, its diagnosis and treatment require increased attention. Although beta-2 microglobulin (b2-MG) is a novel marker of cardiovascular disease, its role in AF has not been evaluated. MATERIAL AND METHODS We conducted a case-control study with 61 patients who had normal heart rhythm (control group) and 60 patients with AF (research group). We analyzed the serum b2-MG levels in both groups and performed multivariate analysis to assess the correlation between b2-MG and left atrial remodeling. In addition, b2-MG levels were compared between the left atrial blood and peripheral venous blood of another set of 57 patients with AF, who underwent cryoballoon ablation. RESULTS There were no statistically significant differences in the baseline characteristics (age, sex, history of hypertension, diabetes mellitus, previous stroke, coronary heart disease, and estimated glomerular filtration rate) of the control and research groups. The left atrial anteroposterior diameters (LAD) and left ventricular end-systolic diameters in the AF group were significantly larger compared to the control group (P<0.01). Serum ß2-MG levels in patients with AF were significantly higher (P<0.01) and positively correlated with the LAD (B-coefficient 25.482, 95% CI 14.410~36.554, P<0.01), serum ß2-MG levels in the left atrial blood were significantly higher than those in peripheral venous blood (P<0.01), and serum ß2-MG levels were an independent predictor of AF. CONCLUSIONS With the development of atrial fibrillation, the serum ß2-MG levels increase and are closely related to the left atrial remodeling due to AF. Therefore, ß2-MG can be an effective biomarker for predicting AF.

Prognostic value of beta-2 microglobulin on mortality in chronic kidney disease patients: A systematic review and meta-analysis

The aim of this study was to delve into whether beta-2 microglobulin could assess all-cause mortality in patients with chronic kidney disease. PubMed and Embase were systematically searched. Hazard risk and 95% CI were pooled using random-effect models. A total of eight studies were involved according to the inclusion and exclusion criterions. By meta-analysis, each 1 mg/L increase in beta-2 microglobulin displayed positive relationships to the risk of all-cause mortality (hazard risk 1.03, 95% CI = 1.02-1.03) and cardiovascular events (hazard risk 1.04, 95% CI = 1.00-1.08) in patients with dialysis. However, the relationship between elevated level of serum beta-2 microglobulin as a categorical variable and mortality was not significant. The prognostic value of elevated beta-2 microglobulin might be significant in ESRD patients with dialysis and a proper cutoff value to predict mortality should be determined in the future.

Enhanced β2-microglobulin binding of a "navigator" molecule bearing a single-chain variable fragment antibody for artificial switching of metabolic processing pathways

Kidney dysfunction increases the blood levels of β2-microglobulin (β2-m), triggering dialysis-related amyloidosis. Previously, we developed a navigator molecule, consisting of a fusion protein of the N-terminal domain of apolipoprotein E (ApoE NTD) and the α3 domain of the major histocompatibility complex class I (MHC α3), for switching the metabolic processing pathway of β2-m from the kidneys to the liver. However, the β2-m binding of ApoE NTD-MHC α3 was impaired in the blood. In the current study, we replaced the β2-m binding part of the navigator protein (MHC α3) with an anti-β2-m single-chain variable fragment (scFv) antibody. The resultant ApoE NTD-scFv exhibited better β2-m binding than ApoE NTD-MHC α3 in buffer, and even in serum. Similar to ApoE NTD-MHC α3, in the mice model ApoE NTD-scFv bound to the liver cells' surfaces in vitro and accumulated mainly in the liver, when complexed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Both ApoE NTD-MHC α3 + DMPC and ApoE NTD-scFv + DMPC significantly switched the β2-m accumulation in mice from the kidneys to the liver, but only the ApoE NTD-scFv + DMPC group showed a significantly higher ratio of β2-m accumulation in the liver versus the kidneys, compared with the control group. These results suggest that the enhanced β2-m binding activity of the navigator molecule increased the efficiency of switching the metabolic processing pathway of the etiologic factor.

Lower serum beta-2 microglobulin levels are associated with worse survival in incident peritoneal dialysis patients

Background

There is a general consensus that elevated serum beta-2 microglobulin (B2M) levels measured at a single time-point are significantly associated with mortality in patients on maintenance dialysis. To date, the majority of prior studies that have examined B2M-associated mortality have been conducted in prevalent hemodialysis patients with little residual renal function (RRF). However, studies in incident peritoneal dialysis (PD) patients are lacking. Moreover, changes in serum B2M levels over time have not been considered in this population.

Methods

We examined the association of time-updated and baseline serum B2M levels with mortality in a 10-year cohort of 725 incident PD patients who were maintained on dialysis between January 2006 and December 2011 using Cox proportional hazards regression analyses. Patients were categorized into tertiles according to B2M levels.

Results

During a median follow-up of 38 (interquartile range 23-64) months, 258 (35.4%) deaths occurred, including 106 (14.6%) and 86 (11.9%) deaths from cardiovascular and infectious causes, respectively. The lowest B2M tertile was associated with a higher risk of all-cause and infectious mortality compared with the middle tertile: the hazard ratios (95% confidence interval) for all-cause deaths were 2.12 (1.38-3.26) and 2.20 (0.96-5.05) in time-varying analyses and 1.52 (1.07-2.17) and 2.41 (1.19-4.88) in baseline analyses. Subgroup analyses showed that this association was particularly observed in females, older patients, those with comorbidities such as diabetes, a lower body mass index, lower albumin levels or those with higher RRF (all P for interactions <0.05).

Conclusions

In incident PD patients, lower B2M levels were independently associated with overall and infectious mortality. These associations can be potentially modified by malnutrition, inflammation and RRF.

Molecular signature of cardiogenic shock

The incidence of cardiogenic shock (CS) has increased remarkably over the past decade and remains a challenging condition with mortality rates of ∼50%. Cardiogenic shock encompasses cardiac contractile dysfunction; however, it is also a multiorgan dysfunction syndrome, often complicated by a systemic inflammatory response with severe cellular and metabolic dysregulations. Here, we review the evidence on the biochemical manifestations of CS, elaborating on current gold standard biomarkers and novel candidates from molecular signatures of CS. Glucose and lactate, both identified over a century ago, remain the only clinically used biomarkers in current predictive risk scores. Novel genomic, transcriptomic, and proteomic data are discussed, and a recently reported molecular score derived from unbiased proteomic discovery, the CS4P, which includes liver fatty acid-binding protein, beta-2-microglobulin, fructose-bisphosphate aldolase B, and SerpinG1 is comprehensively described. Recent advances in -omics technologies provide new insight into a more holistic molecular signature of CS. Thus, we need to open new diagnostic and therapeutic avenues if we aim to improve outcomes.

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Influence of Membranes on Generation of β2 M and Release of Leukocyte Lysosomal Enzymes

Normal leukocyte functional capacity was investigated by evaluation of phagocytosis of opsonised yeast cells in a radiometric test system. After incubation with dialysis membranes (different cellulosic membranes, polysulfon membrane (PS), polymethylmetacrylate membrane (PMMN), the phagocytosis index, expressed as percent decrease with respect to initial values without membrane, decreased by 10%–25%. The most pronounced effect was observed with PS, cuprophane, modified cellulose and PMMA. The results are not related to differences in the viability of PMN during the test procedure; dead PMN amounted to about 4–6.5%. A significant increase in β-NAG and β-Gluc activities was released in the supernatants of the phagocytosis suspensions. This increase activity can be explained by the phagocytosis of PMN but it was not influenced by membrane contact. There was no influence of membrane contact or phagocytosis activity of PMN on the β2M concentration in the supernatant demonstrating that no in vitro generation during incubation with either membrane exists.

Dialysis-related amyloidosis: challenges and solutions

Amyloidosis refers to the extracellular tissue deposition of fibrils composed of low-molecular-weight subunits of a variety of proteins. These deposits may result in a wide range of clinical manifestations depending upon their type, location, and the amount of deposition. Dialysis-related amyloidosis is a serious complication of long-term dialysis therapy and is characterized by the deposition of amyloid fibrils, principally composed of β2 microglobulins (β2M), in the osteoarticular structures and viscera. Most of the β2M is eliminated through glomerular filtration and subsequent reabsorption and catabolism by the proximal tubules. As a consequence, the serum levels of β2M are inversely related to the glomerular filtration rate; therefore, in end-stage renal disease patients, β2M levels increase up to 60-fold. Serum levels of β2M are also elevated in several pathological conditions such as chronic inflammation, liver disease, and above all, in renal dysfunction. Retention of amyloidogenic protein has been attributed to several factors including type of dialysis membrane, prolonged uremic state and/or decreased diuresis, advanced glycation end products, elevated levels of cytokines and dialysate. Dialysis treatment per se has been considered to be an inflammatory stimulus, inducing cytokine production (such as interleukin-1, tumor necrosis factor-α, interleukin-6) and complement activation. The released cytokines are thought to stimulate the synthesis and release of β2M by the macrophages and/or augment the expression of human leukocyte antigens (class I), increasing β2M expression. Residual renal function is probably the best determinant of β2M levels. Therefore, it has to be maintained as long as possible. In this article, we will focus our attention on the etiology of dialysis-related amyloidosis, its prevention, therapy, and future solutions.

Effect of glycemic index and carbohydrate intake on kidney function in healthy adults

BACKGROUND

Replacing carbohydrate with protein acutely increases glomerular filtration rate (GFR) but is associated with faster, long-term kidney disease progression. The effects of carbohydrate type (i.e. glycemic index, GI) on kidney function are unknown.

METHODS

We conducted an ancillary study of a randomized, crossover feeding trial in overweight/obese adults without diabetes or kidney disease (N = 163). Participants were fed each of four healthy, DASH-like diets for 5 weeks, separated by 2-week washout periods. Weight was kept constant. The four diets were: high GI (GI ≥65) with high %carb (58 % kcal) (reference diet), low GI (≤45) with low %carb (40 % kcal), low GI with high %carb; and high GI with low %carb. Plasma was collected at baseline and after each feeding period. Study outcomes were cystatin C, β2-microglobulin (β2M), and estimated GFR based on cystatin C (eGFRcys).

RESULTS

Mean (SD) age was 52 (11) years; 52 % were women; 50 % were black. At baseline, mean (SD) cystatin C, β2M, and eGFRcys were 0.8 (0.1) mg/L, 1.9 (0.4) mg/L, and 104 (16) mL/min/1.73 m(2). Compared to the high GI/high %carb diet, reducing GI, %carb, or both increased eGFRcys by 1.9 mL/min/1.73 m(2) (95 % CI: 1.1, 2.7; P < 0.001), 3.0 mL/min/1.73 m(2) (1.9, 4.0; P < 0.001), and 4.5 mL/min/1.73 m(2) (3.5, 5.4; P < 0.001), respectively. Increases in eGFRcys from reducing GI were significantly associated with increases in eGFRcys from reducing %carb (P < 0.001). Results for cystatin C and β2M reflected eGFRcys.

CONCLUSIONS

Reducing GI increased GFR. Reducing %carb by increasing calories from protein and fat, also increased GFR. Future studies on GI should examine the long-term effects of this increase in GFR on kidney injury markers and clinical outcomes.

TRIAL REGISTRATION

Clinical Trials.gov, number: NCT00608049 (first registered January 23, 2008).

The peptidic middle molecules: is molecular weight doing the trick?

Chronic kidney disease (CKD) is characterized by a gradual endogenous intoxication caused by the progressive accumulation of bioactive compounds that in normal conditions would be excreted and/or metabolized by the kidney. Uremic toxicity now is understood as one of the potential causes for the excess of cardiovascular disease and mortality observed in CKD. An important family of uremic toxins is that of the peptidic middle molecules, with a molecular weight ranging between 500 and 60,000 Da, which makes them, as a consequence, difficult to remove in the process of dialysis unless the dialyzer pore size is large enough. This review provides an overview of the main and best-characterized peptidic middle molecules and their role as potential culprits of the cardiometabolic complications inherent to CKD patients.

Tumour markers and kidney function: a systematic review

Tumour markers represent useful tools in diagnosis and clinical management of patients with cancer, because they are easy to use, minimally invasive, and easily measured in either blood or urine. Unfortunately, such an ideal marker, as yet, does not exist. Different pathological states may increase the level of a tumour marker in the absence of any neoplasia. Alternatively, low levels of tumour markers could be also found in the presence of neoplasias. We aimed at reviewing studies currently available in the literature examining the association between tumour markers and different renal impairment conditions. Each tumour marker was found to be differently influenced by these criteria; additionally we revealed in many cases a lack of available published data.

Comparison of serum concentrations of β-trace protein, β2-microglobulin, cystatin C, and creatinine in the US population

BACKGROUND AND OBJECTIVES

β-trace protein (βTP), β2-microglobulin (β2M), and cystatin C (CysC) have advantages over creatinine for estimating GFR and prognosis. This study compares the distribution of all four markers in the general population and their associations with possible determinants of GFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

βTP and β2M were measured in 7596 participants (aged ≥12 years) of the Third National Health and Nutrition Examination Survey (1988-1994). βTP and β2M concentrations and the proportion of persons with elevated (≥99th percentile for young healthy participants) βTP (≥0.81 mg/L), β2M (≥2.80 mg/L), standardized CysC (≥1.03 mg/L), and creatinine (≥1.2 mg/dl for men and ≥1.0 mg/dl for women) were compared across demographic and clinical factors.

RESULTS

Elevated βTP, β2M, and CysC showed stronger associations with age than elevated serum creatinine, the prevalence of elevated levels reaching 47%, 44%, 58%, and 26%, respectively, by age 80 years. βTP, CysC, and creatinine were higher in men but β2M was not associated with sex. Mexican Americans had lower βTP, β2M, CysC, and creatinine compared with non-Hispanic whites. Hypertension and higher C-reactive protein were associated with elevations in all markers, whereas non-Hispanic black race, body mass index, diabetes, smoking status, triglycerides, HDL cholesterol, and education were not associated in a consistent manner across the different markers.

CONCLUSIONS

βTP, β2M, CysC, and creatinine differ in their associations with demographic and clinical factors, suggesting variation in their non-GFR determinants. Future studies should examine these markers with measured GFR to determine their diagnostic and prognostic utility.

Plasma beta-2 microglobulin is associated with cardiovascular disease in uremic patients

Since beta-2 microglobulin (B2M) is a surrogate marker for middle molecular weight uremic toxins and the major protein component in dialysis-related amyloidosis, it has been frequently studied in dialysis patients. It is not known, however, whether B2M has an impact in patients with chronic kidney disease (CKD) not yet on dialysis. Here we studied the relationship of plasma B2M levels to clinical and cardiovascular outcomes in 142 patients (mean age of 67 years) at different stages of CKD. B2M levels increased with CKD stage and thus were highest in hemodialysis patients. Baseline B2M levels were associated with vascular calcification but not with arterial stiffness or bone density. During a mean follow-up of 969 days, 44 patients died and 49 suffered a cardiovascular event. Higher B2M levels were independently associated with overall and cardiovascular mortality and cardiovascular events in the whole cohort and with cardiovascular events in the predialysis cohort. Moreover, B2M appeared to be a better predictor than well-established factors associated with outcomes in this population, such as estimated glomerular filtration rate ((eGFR), only for predialysis patients), inflammation biomarkers, and other factors included in a propensity score. Thus, we confirm the strong relationship between B2M levels and eGFR and confirm the power of B2M to predict overall and cardiovascular mortality and cardiovascular events in patients at different stages of CKD.

Establishment of a normal reference value for serum β2 microglobulin in Japanese children: reevaluation of its clinical usefulness

OBJECTIVE

Serum β2 microglobulin (β2MG) is considered to be a marker of renal function, which is independently associated with age. However, only a few studies have reported the reference values for β2MG in children thus far, particularly in young children. In this study, we evaluated the distribution of serum β2MG values in healthy Japanese children and assessed its clinical usefulness.

METHOD

The normal reference value of serum β2MG was assessed in serum samples from 1131 normal Japanese children (504 boys and 627 girls; age 0-17 years). To test the validity of the reference value, serum samples from children with various kidney diseases were also examined retrospectively.

RESULTS

The mean values for β2MG were significantly negatively correlated with age (r = -0.47, P < 0.001). No significant difference was observed between the values of boys and girls in any age group. The established β2MG reference range covered 99.7 % of patients with decreased kidney function below 75 % based on their serum creatinine (Cr) value and body length.

CONCLUSION

The newly established β2MG reference value in children can be used to detect kidney impairment in children. Serum β2MG in combination with serum Cr used as markers for predicting glomerular function can provide an accurate detection of kidney dysfunction in children.

Hemodiafiltration improves plasma 25-hepcidin levels: a prospective, randomized, blinded, cross-over study comparing hemodialysis and hemodiafiltration

Background/Aims

Data from studies comparing the effect of hemodiafiltration (HDF) and conventional hemodialysis (HD) on clinically important outcomes are insufficient to support superiority of HDF. None of these studies has been participant-blinded.

Methods

We performed a prospective, randomized, and patient-blinded cross-over study. Twenty patients on chronic HD received either HD for 2 months followed by post-dilution HDF for 2 months or in opposite order. A range of clinical parameters, as well as markers of inflammation, oxidative stress and iron metabolism was measured.

Results

The two treatments were similar with respect to dialysis-related complications, quality of life, and the biomarkers of oxidative stress and inflammation. Compared to HD, 25-hepcidin and β₂-microglobulin were 38 and 32%, respectively, lower after 60 days of HDF (p < 0.001 and p < 0.01, respectively). The consumption of ESA (erythropoietin-stimulating agent) and LMWH (low-molecular-weight heparin) was significantly higher with HDF.

Conclusion

In short term, HDF is not superior to HD regarding dialysis-related complications. The higher ESA consumption observed with HDF can be explained by blood clotting in tubing and dialyzers, as more anticoagulation was needed with post-dilution HDF. In a longer perspective, lowering serum hepcidin levels may improve pathological iron homeostasis.

Enhanced recognition, treatment, and prognosis of tubulointerstitial nephritis and uveitis syndrome

PURPOSE

Tubulointerstitial nephritis and uveitis syndrome (TINU) is a specific form of uveitis that is unfamiliar to most ophthalmologists. Thus, it is frequently overlooked in differential diagnosis. We hypothesized that recognition of subsets of uveitis can facilitate the diagnosis of rare entities such as TINU.

DESIGN

Retrospective case series.

PARTICIPANTS

One thousand nine hundred eighty-five patients with uveitis.

METHODS

We performed a computerized database analysis of patients evaluated for uveitis at the Casey Eye Institute from September 1985 until May 2005. The database includes details about ocular inflammation, including specific diagnosis, anatomic location, laterality, continuity, onset, complications, HLA-B27 status, and relative diagnostic certainty. Additionally, we reviewed all charts of patients diagnosed with TINU or with a presentation of uveitis that was typical of TINU (i.e., bilateral sudden-onset anterior uveitis).

MAIN OUTCOME MEASURES

Prevalence of TINU in identifiable subsets of patients with uveitis, visual acuity (VA), and renal function.

RESULTS

Individuals with TINU (n = 33) represented 1.7% of all patients with uveitis. However, TINU was diagnosed in 32 of the 316 patients (10%) presenting with bilateral sudden-onset anterior uveitis and in 20 of 62 of these patients (32%) who were younger than 20 years. Creatinine levels were more likely to be elevated in patients older than 40. Most patients maintained excellent VA and did not develop clinically significant renal impairment.

CONCLUSION

Tubulointerstitial nephritis and uveitis syndrome is a common cause of uveitis among patients who present with bilateral sudden-onset anterior uveitis. The size of this series clarifies the understanding of the relationship between renal and ocular disease; facilitates recognition of the syndrome; and adds to the knowledge on prognosis, complications, and role of antecedent medications.

Studies on the transcobalamin receptor in hog kidney

The binding of the cobalamin-transcobalamin complex by its solubilized receptor from hog kidney membrane was studied. The receptor bound the complex in a system containing bivalent cations, and the affinity was dependent on the NaCl concentration but not on temperature. The binding of cobalamin-transcobalamin to the receptor had an association constant of approximately 4.6 x 10(9) liter/mol and it was saturable and highly specific as competition by other proteins was not observed. The receptor had higher affinity for the cobalamin-transcobalamin complex (holo-TC) than for transcobalamin (apo-TC). Basic amino compounds known to interfere with tubular reabsorption of proteins did not inhibit the binding. Studies on subcellular fractions supported the view that the receptor was located on the brush border membrane of the kidney.

A study of oral adsorbent in chronic renal failure

In order to examine the effect on the progression of chronic renal failure (CRF), we have applied an oral adsorbent (AST-120) composed of spherical porous carbon particles to patients with chronic renal failure undergoing conservative therapy. Its effect was observed in improvement of uremic symptoms, improvement of slope in linear regression of reciprocal of serum creatinine vs. time plots and delayed initiation of hemodialysis, compared to control patients, together with reduced uremic peak 2a in HPLC analysis of serum and lower levels of beta 2 microglobulin in AST-120 group than in control. The improvements of uremic symptoms, creatinine and 2a levels were confirmed in double blind study where background of patients were evenly randomized between AST-120 and placebo groups and no improvement was observed in placebo group. The result leads us to conclude that the oral adsorbent therapy is expected as an useful therapy for retardation of progression of CRF.

Renal handling of beta 2-microglobulin in patients with cystic fibrosis

We evaluated the renal handling of beta 2-microglobulin (beta 2-M) and creatinine in healthy outpatients (n = 6), normal children hospitalized for infections treated with antibiotics (not including an aminoglycoside) (n = 4); outpatients with cystic fibrosis (CF; n = 12), and hospitalized patients with CF (n = 6) who received a 10- to 14-day course of antibiotic treatment that included an aminoglycoside. The serum beta 2-M concentrations in the normal outpatients (2020.1 +/- 276.6 micrograms/L) were significantly lower (p less than 0.05) than those observed for outpatients (2833.3 +/- 202.6 micrograms/L) or patients with CF (2861.8 +/- 340.5 micrograms/L. There were no significant differences found for creatinine clearance or fractional excretion of beta 2-M when subjects without CF were compared with those with the disease. Furthermore, no significant differences were observed in hospitalized patients with CF when creatinine clearance and fractional excretion of beta 2-M were compared between the initiation and conclusion of aminoglycoside treatment. Glomerular filtration and proximal tubular reabsorption of beta 2-M were not altered in patients with CF. These findings do not support a global defect in proximal renal tubular reabsorption as the underlying cause for altered aminoglycoside clearance in patients with CF.

Alpha 1-microglobulin: a new antigenic component of the epidermo-dermal junction in normal human skin

Monoclonal antibodies to human alpha 1-microglobulin (alpha 1-m), a glycoprotein present in most biological fluids, reacted with the basement membrane of the epidermo-dermal junction and that of eccrine sweat glands in normal human skin. This immunofluorescence was specific in that control antibodies of known well-defined reactivity did not stain these structures. Therefore, alpha 1-m seems to be a new antigenic component of the junction and it may be an interesting antigen to study in diseases of this area.

Localization of alpha 1-microglobulin (HC protein) in normal human tissues: an immunohistochemical study using monoclonal antibodies

Alpha-1-microglobulin is a low molecular weight (approximately 30 000 d) glycoprotein present in biological fluids. It is heterogeneous in charge. A monoclonal antibody was used to investigate the tissue distribution of the protein in normal human tissues and cell lines by indirect immunofluorescence and immunoperoxidase techniques. The protein was demonstrable in cells of the monocyte-macrophage lineage, in thymus and T cell dependent areas of spleen, lymph node and tonsils. It was detected in several lymphoid or nonlymphoid cell lines but not in peripheral blood lymphocytes. The microglobulin was also detectable in the cytoplasm of hepatocytes. Finally, it was observed in glandular secretions (sudoral glands and mucosal glands of the digestive tract) where it may be associated with IgA. Possible explanations for the highly divergent results previously reported with polyclonal antisera to alpha 1 microglobulin are discussed.