Initial renal histology and early response predict outcomes of Brazilian lupus nephritis patients.

OBJECTIVE: We analyzed baseline and follow-up characteristics related to poorer renal outcomes in a Brazilian cohort of admixture race patients with lupus nephritis. METHODS: Overall, 280 outpatients with a diagnosis of systemic lupus erythematosus and previous kidney biopsy of lupus nephritis were recruited from August 2015 to December 2018 and had baseline laboratory and histologic data retrospectively analyzed; patients were then followed-up and data were recorded. The main outcome measure was the estimated glomerular filtration rate at last follow-up. Secondary analyses assessed the impact of initial kidney histology and treatment in long-term kidney survival. RESULTS: Median duration of lupus nephritis was 60 months (interquartile range: 27-120); 40 (14.3%) patients presented progressive chronic kidney disease (estimated glomerular filtration rate <30 and ≥10 ml/min/1.73 m2) or end-stage kidney disease at last visit. Adjusted logistic regression analysis showed that class IV lupus nephritis (odds ratio 14.91; 95% confidence interval 1.77-125.99; p = 0.01) and interstitial fibrosis ≥25% at initial biopsy (odds ratio 5.87; 95% confidence interval 1.32-26.16; p = 0.02), lack of complete or partial response at 12 months (odds ratio 16.3; 95% confidence interval 3.74-71.43; p < 0.001), and a second renal flare (odds ratio 4.49; 95% confidence interval 1.10-18.44; p = 0.04) were predictors of progressive chronic kidney disease. In a Kaplan-Meier survival curve we found that class IV lupus nephritis and interstitial fibrosis ≥25% were significantly associated with end-stage kidney disease throughout follow-up (hazard ratio 2.96; 95% confidence interval 1.3-7.0; p = 0.036 and hazard ratio 4.96; 95% confidence interval 1.9-12.9; p < 0.0001, respectively). CONCLUSION: In this large cohort of admixture race patients, class IV lupus nephritis and chronic interstitial damage at initial renal biopsy together with non-response after 1 year of therapy and relapse were associated with worse long-term renal outcomes.

Demographics and clinical features of elderly patients undergoing regular dialysis in Brazil.

An increasing number of elderly people in renal support is expected in the coming years. The objective of this study was to report the clinical and socio-demographic data of end-stage renal disease (ESRD) adult patients undergoing regular dialysis treatment comparing elderly (≥65 years old) and non-elderly subjects using data from the Brazilian Dialysis Registry database. The regional distribution of the sample was Southeast (48.8%), South (33.7), Northeast (13.1%), Midwest (5.1%), and North (0.1%). A total of 18,030 patients were included in the analysis with elderly patients accounting for 29.5% of the sample. The elderly patients were predominantly male, white, retired, and literate. Elderly ESRD patients had a slightly higher frequency of undernourishment and a lower frequency of obesity than the non-elderly adults. A higher frequency of elderly patients were from the South and Southeast regions. The dialysis treatment of patients from both groups was predominantly funded by the public system, but the percent of non-public funding was higher for the elderly group. The most used initial access in the elderly was the central venous catheter and hemodialysis was the main modality at the beginning of treatment (93.2%), as well as during maintenance therapy (91.8%). Advanced age was associated with greater use of central venous catheter in the first dialysis session. The survival of the elderly on dialysis was lower than that of the non-elderly early in the course of dialysis and this difference increased over time. This is yet the largest national epidemiological study of elderly people on chronic dialysis.

Demographics and clinical features of elderly patients undergoing regular dialysis in Brazil

An increasing number of elderly people in renal support is expected in the coming years. The objective of this study was to report the clinical and socio-demographic data of end-stage renal disease (ESRD) adult patients undergoing regular dialysis treatment comparing elderly (≥65 years old) and non-elderly subjects using data from the Brazilian Dialysis Registry database. The regional distribution of the sample was Southeast (48.8%), South (33.7), Northeast (13.1%), Midwest (5.1%), and North (0.1%). A total of 18,030 patients were included in the analysis with elderly patients accounting for 29.5% of the sample. The elderly patients were predominantly male, white, retired, and literate. Elderly ESRD patients had a slightly higher frequency of undernourishment and a lower frequency of obesity than the non-elderly adults. A higher frequency of elderly patients were from the South and Southeast regions. The dialysis treatment of patients from both groups was predominantly funded by the public system, but the percent of non-public funding was higher for the elderly group. The most used initial access in the elderly was the central venous catheter and hemodialysis was the main modality at the beginning of treatment (93.2%), as well as during maintenance therapy (91.8%). Advanced age was associated with greater use of central venous catheter in the first dialysis session. The survival of the elderly on dialysis was lower than that of the non-elderly early in the course of dialysis and this difference increased over time. This is yet the largest national epidemiological study of elderly people on chronic dialysis.

Cultural adaptation and validation of the "Kidney Disease and Quality of Life--Short Form (KDQOL-SF 1.3)" in Brazil.

The objective of the present study was to translate the Kidney Disease Quality of Life -- Short Form (KDQOL-SF 1.3) questionnaire into Portuguese to adapt it culturally and validate it for the Brazilian population. The KDQOL-SF was translated into Portuguese and back-translated twice into English. Patient difficulties in understanding the questionnaire were evaluated by a panel of experts and solved. Measurement properties such as reliability and validity were determined by applying the questionnaire to 94 end-stage renal disease patients on chronic dialysis. The Nottingham Health Profile Questionnaire, the Karnofsky Performance Scale and the Kidney Disease Questionnaire were administered to test validity. Some activities included in the original instrument were considered to be incompatible with the activities usually performed by the Brazilian population and were replaced. The mean scores for the 19 components of the KDQOL-SF questionnaire in Portuguese ranged from 22 to 91. The components "Social support" and "Dialysis staff encouragement" had the highest scores (86.7 and 90.8, respectively). The test-retest reliability and the inter-observer reliability of the instrument were evaluated by the intraclass correlation coefficient. The coefficients for both reliability tests were statistically significant for all scales of the KDQOL-SF (P < 0.001), ranging from 0.492 to 0.936 for test-retest reliability and from 0.337 to 0.994 for inter-observer reliability. The Cronbach's alpha coefficient was higher than 0.80 for most of components. The Portuguese version of the KDQOL-SF questionnaire proved to be valid and reliable for the evaluation of quality of life of Brazilian patients with end-stage renal disease on chronic dialysis.

Follow-up of patients with epidemic poststreptococcal glomerulonephritis.

In 1998 there was a large outbreak of acute glomerulonephritis (GN) in Nova Serrana, Brazil, caused by group C Streptococcus zooepidemicus and linked to the consumption of contaminated cheese produced with unpasteurized milk. This study describes the follow-up of these patients after a mean of 2 years following the acute episode. Of 134 patients identified in 1998, 69 patients were reexamined and underwent measurements of blood pressure, 24-hour creatinine clearance, microalbuminuria (radioimmunoassay), and urine sediment analysis. Of the original group of 134 patients, 3 patients died in the acute phase and 5 patients (3.7%) required chronic dialysis. Of 69 patients reevaluated, 65 patients (94%) were adults (mean age, 39 +/- 2 [SE] years) and 47 patients (68%) were women. At the follow-up examination, we found arterial hypertension in 42% of subjects (27 of 64 subjects), serum creatinine levels greater than 1.2 mg/dL in 12% (10 of 68 subjects), reduced creatinine clearance (<80 mL/min/1.73 m(2)) in 30% (20 of 67 subjects, 2 of them on chronic dialysis therapy), and increased microalbuminuria (>20 microg/min) in 34% (22 of 65 subjects). Increased microalbuminuria and/or reduced creatinine clearance were detected in 48% of the subjects (31 of 65 subjects). Patients with microalbuminuria had greater diastolic blood pressure than those without microalbuminuria (mean, 98 +/- 4 versus 88 +/- 2 mm Hg; P = 0.02). In conclusion, after a mean of 2 years, patients with epidemic poststreptococcal GN caused by S zooepidemicus present a high rate of hypertension and frequent abnormalities of renal function, with some having reached end-stage renal disease. Longer follow-up will be important to define the prognosis of these patients.

Application of restriction endonuclease analysis of chromosomal DNA in the study of Staphylococcus aureus colonization in continuous ambulatory peritoneal dialysis patients.

The relationship between nasal and skin colonization with Staphylococcus aureus and subsequent infection in continuous ambulatory peritoneal dialysis (CAPD) patients in Brazil has been documented by restriction endonuclease analysis of plasmid DNA. However, S. aureus strains without detectable plasmids have been identified. Using restriction endonuclease analysis of chromosomal DNA hybridized with an rRNA gene probe, we document the diversity of S. aureus strains without detectable plasmids colonizing CAPD patients. Ten paired strains without detectable plasmids from five patients were studied by restriction endonuclease analysis of chromosomal DNA and by phage typing. Five different profiles were obtained by restriction endonuclease analysis of chromosomal DNA. Although four of the ten paired isolates were nontypeable by phage typing, all were discriminated by restriction endonuclease analysis of chromosomal DNA. These results demonstrate that restriction endonuclease analysis of chromosomal DNA is a useful epidemiologic tool and complements the restriction endonuclease analysis of plasmid DNA of S. aureus by providing a means of typing strains without detectable plasmids.

Osteomalacia secondary to renal tubular acidosis in a patient with primary Sjögren's syndrome.

We report a case of a 41-year-old woman whose disease manifested as osteomalacia and whose etiological investigation revealed renal tubular acidosis secondary to primary Sjögren's syndrome. Proximal tubular dysfunction was also present and was documented by increased urinary excretion of beta-2-microglobulin and retinol-binding protein. The patient showed clinical and laboratory improvement after treatment with oral potassium citrate, calcium supplements and steroids.

Influence of renal function on spontaneous dietary intake and on nutritional status of chronic renal insufficiency patients.

OBJECTIVE: To analyze the spontaneous food intake and the nutritional parameters of patients with different degrees of chronic renal insufficiency (CRI) at the onset of predialysis treatment. DESIGN: Cross-sectional. SETTING: Outpatient Clinic of the Nephrology Division of Federal University of São Paulo, Brazil. SUBJECTS: The analysis involved 487 (187 women and 300 men) patients with moderate to advanced CRI who were evaluated in the first visit to the clinic. RESULTS: Patients were divided according to creatinine clearance (CrCl) quartiles. CrCl in the first quartile was lower than 19.9 ml/min/1.73 m(2) and in the fourth one was higher than 43 ml/min/1.73 m(2). Energy intake was significantly (P<0.05) lower in the first quartile when compared with the fourth one while protein intake estimated by protein equivalent of nitrogen appearance (PNA) was significantly lower in the first, second and third quartiles in comparison with the fourth (P<0.05). Body mass index (BMI) and percentage of ideal body weight were significantly decreased in the three lowest levels of renal function. Standard per cent of triceps skinfold thickness was lower in the first quartile when compared with the fourth one. Compared with the fourth quartile, standard per cent of midarm muscle circumference (MAMC) was lower in the second and in the third quartile. CrCl correlated directly and significantly with PNA (r=0.30; P<0.01), energy intake (r=0.17; P<0.01), and MAMC (r=0.20; P<0.01). In a multiple linear regression analysis, controlling for energy and protein intake, CrCl correlated significantly and positively with BMI and MAMC. CONCLUSION: This study suggests that a spontaneous decrease in energy and protein intake as well as in anthropometric indices follows a decline in renal function in patients with no previous dietary intervention.

Factors associated with acceptance of patients for chronic dialysis.

BACKGROUND/AIMS: There is evidence suggesting that a number of patients with chronic renal failure (CRF) are not accepted for maintenance dialysis treatment, however, the factors that influence this process are not well known. METHODS: Data from patients who died of CRF in the city of São Paulo in 1998 were recorded from death certificates. The International Classification of Diseases, tenth revision, was used to select patients with an underlying cause of death associated with CRF. Patients who received dialysis were identified through the files of the São Paulo State Health Secretariat. Subjects accepted for dialysis or not were compared regarding demographic, socioeconomic factors and primary renal disease. RESULTS: Of 1225 subjects, 414 (33.8%) received dialysis and 811 (66.2%) did not. The adjusted odds ratio (OR) (95% CI) of not being accepted for dialysis was greater in older (> 65 years; OR: 2.94 (2.28 3.79)) and in younger subjects (<18 years; OR: 3.20 (1.16-8.28)) compared to those aged 18-64 years. Single subjects had a greater chance of not being accepted for dialysis than married individuals (OR: 1.28 (1.01-1.65)). Patients with diabetes were less likely to receive dialysis than those with an unknown cause of renal failure (OR: 1.37 (1.01-1.86)). CONCLUSION: Age, underlying cause of renal failure and social support are associated with the acceptance of CRF patients for dialysis. Further studies are necessary to examine interventions to improve the access to treatment for potentially eligible patients.

Effect of age and gender on kidney function in renal transplant donors: a prospective study.

We evaluated the long-term residual renal function in 64 living related kidney donors. Our main objective was to identify baseline factors, including gender and age, that could predict renal impairment after nephrectomy. Forty-four (69%) of the 64 donors were women. The mean +/- SEM age of those studied was 36 +/- 1.3 years and their mean +/- SEM duration of follow-up was 62 +/- 4.9 months (range, 6 to 174). Overall mean serum creatinine concentration after kidney donation was increased compared to baseline values (1.13 mg/dl vs 0.92 mg/dl, respectively, p < 0.001). At the last follow-up visit, post-nephrectomy mean glomerular filtration rate (GFR) values, adjusted for body surface area, age at donation, baseline serum creatinine and duration of follow-up, measured by 99mTc-DTPA were significantly lower in women than in men (72.11 ml/min vs 87.17 ml/min, respectively, p = 0.02). At follow-up, mean effective renal plasma flow, adjusted for the same variables, measured by 131I-hippuran was also significantly lower in women compared to men (318.07 ml/min vs 400.82 ml/min, respectively, p < 0.01). Eleven of twelve patients with post-nephrectomy GFR values less than 60 ml/min were women. Following nephrectomy, serum creatinine concentration increased significantly as a function of greater age at donation in women but not in men. Similarly, in women but not in men, follow-up GFR measurements decreased significantly as a function of age after adjusting for baseline serum creatinine and duration of follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of IgG-rheumatoid factor in sera of patients with acute poststreptococcal glomerulonephritis and its relationship with circulating immunecomplexes.

Rheumatoid factors (RF) were measured in sera from 75 patients with acute poststreptococcal glomerulonephritis (APSGN) and compared with normal controls, patients with rheumatoid arthritis in activity and acute rheumatic fever. Using two sensitive and specific solid phase radioimmunoassays, IgM-RF and IgG-RF were detected, respectively, in 15% and 32% of the patients with APSGN. A positive correlation (r = 0.37, n = 75, p less than 0.05) was obtained between serum levels of IgG-RF and circulating immune complexes determined by conglutinin assay. Chromatographic studies in serum from two patients with APSGN demonstrated that the circulating IgG-RFs were mainly free, not complexed. It is suggested that RFs, particularly of the IgG class, may participate in the pathogenesis of the renal injury in some patients with APSGN.

Staphylococcus aureus skin carriage and development of peritonitis in patients on continuous ambulatory peritoneal dialysis.

We conducted a 15-month prospective study to investigate the skin carriage of Staphylococcus aureus and the development of peritonitis in 43 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Sixteen of 43 patients (37%) were chronic carriers of S. aureus in the anterior nares and/or in the exit-site of the catheter; 12 patients (28%) were intermittent carriers, and 15 (35%) were noncarriers. Fifty episodes of peritonitis occurred during a total of 422 patient-months of observation. S. aureus was responsible for 16 episodes of peritonitis diagnosed in 15 patients. All episodes of S. aureus peritonitis occurred in chronic and intermittent carriers. Phage typing was performed on isolates from 8 patients with S. aureus peritonitis, and they were found to have the same phage type as that previously carried in the skin. We conclude that CAPD patients who are chronic or intermittent carriers of S. aureus are at higher risk of development of peritonitis than noncarriers.

Effect of sodium fusidate and ofloxacin on Staphylococcus aureus colonization and infection in patients on continuous ambulatory peritoneal dialysis.

The effectiveness of sodium fusidate and ofloxacin to eliminate nasal and catheter exit-site Staphylococcus aureus colonization and to prevent infections was compared in 31 patients on continuous ambulatory peritoneal dialysis (CAPD). In a prospective randomized study, 9 patients were treated with topical 2% sodium fusidate ointment applied in the anterior nares and in the pericatheter skin twice daily for 5 days; 9 subjects received oral ofloxacin 200 mg taken every 48 hours for 5 days and 13 subjects were in the control group. Treatment courses were repeated at one-month intervals. Mean duration of follow-up was 7.8 months (242 patients-month). Follow-up samples from the nares and the catheter exit-site were obtained every month from all participants to determine the presence of S. aureus. Development of S. aureus exit-site infection and peritonitis were assessed. During the study, S. aureus was recovered from 45%, 59% and 52% of the samples from the nares and/or exit-site in the sodium fusidate, ofloxacin and control groups, respectively (p = 0.13). S. aureus grew less frequently (p < 0.01) in samples from the exit-site in the sodium fusidate than in the other two groups. Eradication of nasal colonization (two negative cultures within one month) was observed in 43%, 40% and 33% of the cases in the sodium fusidate, ofloxacin and control groups, respectively (p > 0.50). The corresponding figures for exit-site eradication were 43%, 33% and 11%, respectively (p = 0.34). Twenty-four S. aureus-associated infection episodes (12 of exit-site and 12 of peritonitis) were diagnosed in 16 of the 31 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of antimicrobial susceptibility testing for epidemiology and the selection of oral, parenteral and topical regimens for control of CAPD-associated Staphylococcus aureus infection.

Staphylococcus aureus is an important cause of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Using standard broth microdilution and disk diffusion methodology, we evaluated the in vitro activity of selected antimicrobial agents against S. aureus strains isolated from CAPD patients to assess candidate regimens for 1) topical agent control of colonization, 2) oral chemotherapy of CAPD infectious complications, and 3) parenteral treatment of serious CAPD-associated staphylococcal infections. A total of 34 isolates (31 patients) of S. aureus were available for testing, including 29 isolates (29 patients) from pericatheter skin, four isolates (four patients) from the nares, and one isolate from an episode of peritonitis. Six of the isolates were oxacillin-resistant (ORSA). The antimicrobial agents tested by broth microdilution included 17 different quinolones, 10 cephalosporins, six glycopeptides, two aminoglycosides, and imipenem. A total of eight potential topical agents, including the antistaphylococcal agent mupirocin, were tested by disk diffusion. All of the quinolones, with the exception of nalidixic acid (MIC90 greater than 16 micrograms/ml), had excellent activity against both ORSA and oxacillin-susceptible S. aureus (OSSA) with the most active agent being WIN57273 (MIC90 less than or equal to 0.015 microgram/ml). Imipenem and the cephalosporins, with the exception of cefixime, ceftazidime, and E-1040, possessed good activity against OSSA. None of the beta-lactam agents tested were active against ORSA. Likewise, the aminoglycosides, amikacin and gentamicin, exhibited good activity against OSSA strains but no activity against ORSA strains. All glycopeptides tested demonstrated excellent activity against ORSA strains. Of the topical antimicrobial agents tested only bacitracin, mupirocin, and nitrofurantoin were active against all OSSA and ORSA strains tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Late diagnosis of chronic renal failure and the quality of life during dialysis treatment.

We evaluated the quality of life of 101 hemodialysis patients who had a late < or = 3 months before starting dialysis, N = 47) or early (> or = 6 months, N = 54) diagnosis of chronic renal failure. At the time of the survey patients had been stable on dialysis for at least 3 months and for less than 24 months; median duration of dialysis was 9.1 months. Quality of life was measured by the kidney disease questionnaire (including the intensity and duration of physical symptoms, fatigue, depression, relationship with others and frustration), the health and life satisfaction indices, functional status (Karnofsky scale), and the time trade-off method. Scores for the several indicators of quality of life were closely similar for the late and early diagnosis groups. Health satisfaction compared to one year prior to dialysis was slightly better for the early diagnosis group. For both groups, functional status was a little worse during the first year of dialysis than one year before its start. In the late diagnosis group, elderly patients and diabetics had more impairment in several dimensions assessed. In addition, in this group greater income was significantly correlated with better physical performance (r = 0.52, P < 0.001) and with health satisfaction (r = 0.36, P = 0.027). These findings suggest that after a median duration of 9 months on a dialysis program, patients with a late and early diagnosis of chronic renal failure have a similar performance in terms of quality of life parameters. Age, diabetes and income are associated with the quality of life of patients with a late diagnosis.

Late diagnosis of chronic renal failure.

A comparison was made between patients with a late diagnosis of chronic renal failure (1 month or less before starting dialysis, N = 96) and those with an early diagnosis (6 months or more, N = 45) in terms of the following aspects: referral characteristics during the pre-dialysis phase, demographic details and patient biochemistry prior to maintenance dialysis. Information was obtained by surveying consecutive patients with primary renal disease admitted to a university dialysis unit in São Paulo. Fifty-three percent of all patients surveyed had a late diagnosis. These patients had a lower median duration of symptoms (2 vs 6 months, P < 0.01) and were less likely to be referred for dialysis by a nephrologist (9% vs 51%, P < 0.001) than early diagnosis patients. In the early diagnosis group, 7 patients (16%) had follow-up care for less than 6 months and 11 (24%) did not receive any follow-up; 21 patients (47%) did not follow a low-protein diet. At the start of dialysis, patients with a late diagnosis had higher blood pressure and a higher rate of pulmonary infections (19% vs 4%, P = 0.03). Mean concentrations of BUN, serum creatinine and potassium were significantly higher and mean blood hematocrit was lower for the late diagnosis group. After 3 months of dialysis, the mortality rate was higher in the late than in the early diagnosis group (22.9% vs 6.7%, P = 0.02). Late diagnosis of chronic renal failure and lack of adequate follow-up care, prior to the start of dialysis, are common. Interventions to promote early diagnosis of chronic renal failure and to improve compliance with regular nephrological follow-up can be important to reduce the morbidity and the mortality of patients with chronic renal insufficiency.

Level of fetal hemoglobin as an indicator of clinical complications in sickle cell anemia.

1. The fetal hemoglobin (HbF) level was used as an indicator of the development of severe clinical complications in 89 patients with sickle cell anemia (SCA). 2. HbF was determined by the alkali denaturation technique. The mean HbF level was 6.7 +/- 4.2% (range, 0.7 to 19.2%) of total hemoglobin. 3. Major organ failures were considered to be terminal events of morbidity and included 8 cerebrovascular accidents, 13 aseptic necroses of the femoral head and 17 leg ulcer episodes. 4. The characteristics of the test, including sensitivity, specificity and positive predictive value were analyzed for different levels of HbF. 5. The overall specificities were 76, 76, and 85% for HbF levels greater than or equal to 8, 10 and 12%, respectively. The sensitivity of the test was low. The positive predictive value reached 71% for children with HbF greater than or equal to 8%. The data suggest that HbF level may be a useful indicator of the possibility of a patient developing serious clinical complications.

Renal dysfunction in patients with sickle cell anemia or sickle cell trait.

Patients with sickle cell anemia (Hb SS) or sickle cell trait (Hb AS) may present several types of renal dysfunction; however, comparison of the prevalence of these abnormalities between these two groups and correlation with the duration of disease in a large number of patients have not been thoroughly investigated. In a cross-sectional study using immunoenzymometric assays to measure tubular proteinuria, microalbuminuria, measurement of creatinine clearance, urinary osmolality and analysis of urine sediment, we evaluated glomerular and tubular renal function in 106 adults and children with Hb SS (N = 66) or Hb AS (N = 40) with no renal failure (glomerular filtration rate (GFR) > 85 ml/min). The percentage of individuals with microalbuminuria was higher among Hb SS than among Hb AS patients (30 vs 8%, P < 0.0001). The prevalence of microhematuria was similar in both groups (26 vs 30%, respectively). Increased urinary levels of retinol-binding protein or beta 2-microglobulin were detected in only 3 Hb SS and 2 Hb AS patients. Urinary osmolality was reduced in patients with Hb SS or with Hb AS; however, it was particularly evident in Hb SS patients older than 15 years (median = 393 mOsm/kg, range = 366-469) compared with Hb AS patients (median = 541 mOsm/kg, range = 406-722). Thus, in addition to the frequently reported early reduction of urinary osmolality and increased GFR, nondysmorphic hematuria was found in 26 and 30% of patients with Hb SS or Hb AS, respectively. Microalbuminuria is an important marker of glomerular injury in patients with Hb SS and may also be demonstrated in some Hb AS individuals. Significant proximal tubular dysfunction is not a common feature in Hb SS and Hb AS population at this stage of the disease (i.e., GFR > 85 ml/min).

Radioimmunoassay for IgG and IgM rheumatoid factors.

The present paper describes two solid phase radioimmunoassays for detecting IgG and IgM rheumatoid factors (RF). Basically, serum rheumatoid factors were bound to rabbit IgG previously adsorbed to wells of flexible microtiter plates and quantitated after the addition of 125I-Fab anti-human gamma Fd for the IgG-RF assay or 125I-IgG anti-mu chain for the IgM-RF assay. The IgG and IgM rheumatoid factor assays were tested on 56 and 30 control sera, respectively. The upper normal limits for these assays were taken for cpm test serum/cpm control pool as 1.00 (0.76 + 0.24; X + 2SD) and 1.39 (0.73 + 0.66; X + 2SD) for IgG-RF and IgM-RF, respectively. When applied to sera of patients with rheumatoid arthritis, IgM-rheumatoid factor was detected in 15 of 15 (100%) patients, and IgG-rheumatoid factor in 15 of 17 (88%). The radioimmunoassay results for both rheumatoid factors were significantly higher for these patients than for the normal control sera (P less than 0.01).