Epstein-Barr virus and Burkitt's lymphoma. Associations in Iraqi Kurdistan and twenty-two countries assessed in the International Incidence of Childhood Cancer

Background

Burkitt's lymphoma (BL) has worldwide variations in incidence that are related to the age of Epstein-Barr virus (EBV) infection. This study examined the age-specific incidence rate (ASIR) of BL and community EBV seropositivity in Iraqi Kurdistan and compared results with data from countries tabulated in the International Incidence of Childhood Cancer volume 3 (IICC-3).

Methods

The ASIR (95% confidence intervals) of BL in Sulaimani Governorate of Iraqi Kurdistan were calculated for the years 2010–2020. Specimens from 515 outpatients were tested for IgG and IgM antibodies to EBV viral capsid antigen.

Results

In Sulaimani, 84% of BL occurred under 20 years of age, with an ASIR of 6.2 (4.7–7.7) per million children. This ASIR was not significantly different than that of Egypt, Morocco, Israel, Spain, or France. It was slightly higher than the ASIR of the United States, the United Kingdom, and Germany and markedly higher than for Asia and South Africa. In Africa and much of Asia, early childhood EBV exposure predominates, with nearly all children being infected by 5 years of age. In Sulaimani, just over 50% of children were EBV seropositive at 3 years old and 90% seropositivity was reached at 15 years of age. In Europe and North America, seropositivity is commonly delayed until adolescence or young adulthood and adult predominates over childhood BL.

Conclusion

In the Middle East, childhood BL is relatively common and adult BL is rare. In Sulaimani, EBV seropositivity increases progressively throughout childhood and reaches 92% at mid-adolescence. This may reflect the Mid East more widely. We suggest that the high childhood and low adult BL rates may be a regional effect of a pattern of EBV exposure intermediate between early childhood and adolescent and young adult infections.

The causes and frequency of kidney allograft failure in a low-resource setting: observational data from Iraqi Kurdistan

Background

In the developing world, transplantation is the most common long-term treatment for patients with end-stage renal disease, but rates and causes of graft failure are uncertain.

Methods

This was a retrospective outcomes study of renal transplant patients seen in Iraqi Kurdistan nephrology clinics in the year 2019. In 2019, 871 renal transplant patients were registered and outcomes followed through 12/31/2020. Indicated renal biopsies were obtained on 431 patients at 1 day to 18 years post-transplantation. Outcomes were compared with United States Renal Data System (USRDS) living donor reports.

Results

All donors were living. The recipient age was 38.5 ± 13.3 years, 98.2% were < 65 years old, 3.7% had previous transplants, and 2.8% had pretransplant donor-specific antibodies (DSA). Gehan-Breslow estimated failure rates for all-cause, return to HD, and death with functional graft were 6.0, 4.2, and 1.9% at 1 year and 18.1, 13.7, and 5.1% at 5 years post-engraftment (USRDS 2000; 1 year: 7.0, 5.0, 2.6%; 5 year: 22.3, 15.2, 10.6%. USRDS 2010; 1 year: 3.7, 2.4, 1.4%; 5 year: 15.3, 9.6, 7.3%). The median graft survival was 15 years. Acute tubular injury (ATI), infarction, and acute T cell-mediated rejection accounted for 22.2% of graft loss, with > 75% of these failures taking place in the first year. Most graft failures occurred late, at a median post-transplant time of 1125 (interquartile range, 365–2555) days, and consisted of interstitial fibrosis and tubular atrophy (IF/TA) (23.8%), transplant glomerulopathy (13.7%), and acquired active antibody-mediated rejection (12.0%). The significant predictors of graft loss were C4d + biopsies (P < 0.01) and advanced IF/TA (P < 0.001).

Conclusions

Kurdistan transplant patients had graft failure rates similar to living donors reported by the USRDS for the year 2000 but higher than reported for 2010. Compared to USRDS 2010, Kurdistan patients had a moderate excess of HD failures at one and 5 years post-engraftment. Nevertheless, prolonged survival is the norm, with chronic disorders and acquired DSA being the leading causes of graft loss.

The causes and frequency of kidney allograft failure in a low-resource setting: Data from Iraqi Kurdistan.. [DOI: 10.21203/rs.3.rs-233389/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background In the developing world, transplantation is the most common long-term treatment for patients with end-stage renal disease, but rates and causes of graft failure are uncertain. Methods In 2019, in Iraqi Kurdistan, 301 of 871 renal transplant patients had indicated graft biopsies. Outcomes were followed over the subsequent year of 2020. Results The post-transplantation time ranged from one day to 18 years. All donors were living. Approximately 15% of transplants were preemptive. Pretransplant hemodialysis (HD) was twice weekly and less than one year. The median recipient age was 39 (IQR 28 to 48) years. 5.5% of recipients had previous transplants; 3.7% had pretransplant donor-specific antibodies (DSA). The Kaplan-Meier estimated graft failure rates for all-cause, return to HD, and death with functional graft (DWFG) were 9.1%, 6.3%, and 2.9% at one year and 23.8%, 6.3%, and 7.4% at five years. The median death-censored graft survival was 15 years. The most frequent biopsy diagnoses associated with graft failure were interstitial fibrosis and tubular atrophy (IF/TA) (23.1%), transplant glomerulopathy (13.7%), and acquired active antibody-mediated rejection (11.1%). The significant predictors of graft loss were C4d + biopsies (P < 0.01) and advanced IF/TA (P < 0.001). Conclusions These Iraqi patients had estimated graft failure rates similar to the United States (US) Renal Data System living-donor outcomes reported for the year 2000. The inability to approach recent US graft survivals may owe to inadequate pretransplant dialysis. Nevertheless, prolonged survival made chronic disorders and acquired DSA the leading causes of graft failure and is creating a need for second transplants.

Effects of bodybuilding supplements on the kidney: A population-based incidence study of biopsy pathology and clinical characteristics among middle eastern men

Background

The incidence of kidney diseases among bodybuilders is unknown.

Methods

Between January 2011 and December 2019, the Iraqi Kurdistan 15 to 39 year old male population averaged 1,100,000 with approximately 56,000 total participants and 25,000 regular participants (those training more than 1 year). Annual age specific incidence rates (ASIR) with (95% confidence intervals) per 100,000 bodybuilders were compared with the general age-matched male population.

Results

Fifteen male participants had kidney biopsies. Among regular participants, diagnoses were: focal segmental glomerulosclerosis (FSGS), 2; membranous glomerulonephritis (MGN), 2; post-infectious glomeruonephritis (PIGN), 1; tubulointerstitial nephritis (TIN), 1; and nephrocalcinosis, 2. Acute tubular necrosis (ATN) was diagnosed in 5 regular participants and 2 participants training less than 1 year. Among regular participants, anabolic steroid use was self-reported in 26% and veterinary grade vitamin D injections in 2.6%. ASIR for FSGS, MGN, PIGN, and TIN among regular participants was not statistically different than the general population. ASIR of FSGS adjusted for anabolic steroid use was 3.4 (− 1.3 to 8.1), a rate overlapping with FSGS in the general population at 2.0 (1.2 to 2.8). ATN presented as exertional muscle injury with myoglobinuria among new participants. Nevertheless, ASIR for ATN among total participants at 1.4 (0.4 to 2.4) was not significantly different than for the general population at 0.3 (0.1 to 0.5). Nephrocalcinosis was only diagnosed among bodybuilders at a 9-year cumulative rate of one per 314 vitamin D injectors.

Conclusions

Kidney disease rates among bodybuilders were not significantly different than for the general population, except for nephrocalcinosis that was caused by injections of veterinary grade vitamin D compounds.

Progressive Nephron Loss in Aging Kidneys: Clinical–Structural Associations Investigated by Two Anatomical Methods

Two major studies of structural changes associated with aging in human kidneys are reviewed and new information presented. The studies are the Monash University stereologically analyzed series of 319 autopsy kidneys from the United States in which 44% were white and the Mayo Clinic CT angiogram/biopsy analysis of 1,388 US kidney donors in which 97% were white. Hypertension rates in the Monash series were 48% and included moderate and severe hypertension. In the Mayo Clinic study, 12% had mild hypertension. The studies showed no relationship between glomerular number and hypertension except for a weak relationship with older white women in the Monash series. An inverse relationship was present between glomerular number and glomerular volume, a reciprocity that tended to enhance glomerular mass and by inference filtration capacity with lower nephron numbers. This relationship seemed to be present whether low nephron numbers were intrinsic or acquired. In the Mayo Clinic studies, pretransplant iothalamate clearances demonstrated that single nephron (SN) glomerular filtration rates (GFR) were similar throughout the range of glomerular number in subjects younger than 70 years, but that increased SNGFR correlated with nephron hypertrophy and increased nephrosclerosis particularly at 70 years of age and over. Hypertension at least through middle age cannot be related to a deficiency of glomeruli, but glomeruli are lost with later aging in association with adaptive nephron hypertrophy that can maintain GFR near normal. These studies help define an age‐related nephropathy that overlaps with hypertension as a potential cause of end‐stage renal disease when glomerulosclerosis is advanced.

mTOR-mediated podocyte hypertrophy regulates glomerular integrity in mice and humans

The cellular origins of glomerulosclerosis involve activation of parietal epithelial cells (PECs) and progressive podocyte depletion. While mammalian target of rapamycin-mediated (mTOR-mediated) podocyte hypertrophy is recognized as an important signaling pathway in the context of glomerular disease, the role of podocyte hypertrophy as a compensatory mechanism preventing PEC activation and glomerulosclerosis remains poorly understood. In this study, we show that glomerular mTOR and PEC activation-related genes were both upregulated and intercorrelated in biopsies from patients with focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, suggesting both compensatory and pathological roles. Advanced morphometric analyses in murine and human tissues identified podocyte hypertrophy as a compensatory mechanism aiming to regulate glomerular functional integrity in response to somatic growth, podocyte depletion, and even glomerulosclerosis - all of this in the absence of detectable podocyte regeneration. In mice, pharmacological inhibition of mTOR signaling during acute podocyte loss impaired hypertrophy of remaining podocytes, resulting in unexpected albuminuria, PEC activation, and glomerulosclerosis. Exacerbated and persistent podocyte hypertrophy enabled a vicious cycle of podocyte loss and PEC activation, suggesting a limit to its beneficial effects. In summary, our data highlight a critical protective role of mTOR-mediated podocyte hypertrophy following podocyte loss in order to preserve glomerular integrity, preventing PEC activation and glomerulosclerosis.

Non-Hodgkin Lymphoma in the Middle East Is Characterized by Low Incidence Rates With Advancing Age

PURPOSE

In the Middle East, incidence rate ratios (IRRs) of non-Hodgkin lymphoma (NHL) to Hodgkin lymphoma (HL) are more than 50% lower than the United States.

MATERIALS AND METHODS

Age-specific incidence rates (ASIRs), age-adjusted incidence rates (AAIRs), and IRRs of NHL:HL were compared using the cancer registries of Iraq, Jordan, Saudi Arabia, and US SEER.

RESULTS

The NHL AAIR (95% CI) per 100,000 population was 4.4 (4.1 to 4.7) for Iraq, 5.4 (4.6 to 6.2) for Jordan, 4.7 (4.4 to 5.1) for Saudi Arabia, and 13.2 (13.0 to 13.4) for the United States. The HL AAIR was 1.8 (1.6 to 2.0) for Iraq, 1.8 (1.4 to 2.2) for Jordan, 2.1 (1.9 to 2.2) for Saudi Arabia, and 2.3 (2.2 to 2.4) for the United States, with respective NHL:HL IRR of 2.4 (2.2 to 2.7), 3.0 (2.4 to 3.8), 2.2 (2.0 to 2.5), and 5.7 (5.5 to 6.0). NHL ASIRs for the Middle East and the United States were similar until 30 to 39 years of age. Thereafter, ASIR of NHL peaked at 20 to 33 per 100,000 at age 70 years in the Middle East regions, all much lower than the US age 70 years rate of greater than 100 per 100,000. Diffuse large B-cell lymphoma (DLBCL) represented 52% of NHL in Sulaimaniyah Province of Iraq and 51% of NHL in Saudi Arabia. Both regions had AAIR for DLBCL less than 42% of DLBCL in US SEER. Pediatric Epstein-Barr virus-related Burkitt's lymphoma at 8% was the second most frequent NHL in Sulaimaniyah but made little contribution to overall NHL rates.

CONCLUSION

The incidence of HL was slightly lower than in the United States, but it was the markedly lower rates of adult NHL with advancing age, including the predominant DLBCL, that accounted for the low NHL:HL IRR in these Middle Eastern countries.

Incidence of glomerulonephritis and non-diabetic end-stage renal disease in a developing middle-east region near armed conflict

BACKGROUND

Estimates of the incidence of glomerulonephritis (GN) and end-stage renal disease (ESRD) in an Iraqi population are compared with the United States (US) and Jordan.

METHODS

The study set consist of renal biopsies performed in 2012 and 2013 in the Kurdish provinces of Northern Iraq. The age specific and age standardized incidence of GN was calculated from the 2011 population. ESRD incidence was estimated from Sulaimaniyah dialysis center records of patient's inititating hemodialysis in 2017.

RESULTS

At an annual biopsy rate of 7.8 per 100,000 persons in the Kurdish region, the number of diagnoses (2 years), the average age of diagnosis, and annual age standardized incidence (ASI)/100,000 for focal segmental glomerulosclerosis (FSGS) was n = 135, 27.3 ± 17.6 years, ASI = 1.6; and for all glomerulonephritis (GN) was n = 384, 30.4 ± 17.0 years, ASI = 5.1. FSGS represented 35% of GN biopsies, membranous glomerulonephritis 18%, systemic lupus erythematosus 13%, and immunoglobulin A nephropathy 7%. For FSGS and all GN, the peak age of diagnoses was 35-44 years of age with age specific rates declining after age 45. The unadjusted annual ESRD rate was 60 per million with an age specific peak at 55-64 years and a decline after age 65. The assigned cause of ESRD was 23% diabetes, 18% hypertension, and 12% GN with FSGS comprising 41% of biopsy-diagnosed, non-diabetic ESRD.

CONCLUSIONS

The regional incidence of ESRD in Northern Iraq is much lower than the crude incidences of 100 and 390 per million for Jordan and the US respectively. This is associated with low renal disease rates in the Iraqi elderly and an apparent major contribution of FSGS to ESRD.

New insights on glomerular hyperfiltration: a Japanese autopsy study

It has been suggested that low nephron number contributes to glomerular hypertension and hyperperfusion injury in progressive chronic kidney disease (CKD). The incidence of CKD in Japan is among the highest in the world, but the reasons remain unclear. We estimated total nephron (glomerular) number (NglomTOTAL) as well as numbers of nonsclerosed (NglomNSG) and globally sclerosed glomeruli (NglomGSG), and the mean volume of nonsclerosed glomeruli (VglomNSG) in Japanese normotensive, hypertensive, and CKD subjects and investigated associations between these parameters and estimated glomerular filtration rate (eGFR). Autopsy kidneys from age-matched Japanese men (9 normotensives, 9 hypertensives, 9 CKD) had nephron number and VglomNSG estimated using disector/fractionator stereology. Subject eGFR, single-nephron eGFR (SNeGFR), and the ratio SNeGFR/VglomNSG were calculated. NglomNSG in Japanese with hypertension (392,108 ± 87,605; P < 0.001) and CKD (268,043 ± 106,968; P < 0.001) was less than in normotensives (640,399 ± 160,016). eGFR was directly correlated with NglomNSG (r = 0.70, P < 0.001) and inversely correlated with VglomNSG (r = -0.53, P < 0.01). SNeGFR was higher in hypertensives than normotensives (P = 0.03), but was similar in normotensives and CKD, while the ratio SNeGFR/VglomNSG was similar in normotensives and hypertensives but markedly reduced in CKD. Nephron number in Japanese with hypertension or CKD was low. This results in a higher SNeGFR in hypertensives compared with normotensive and CKD subjects, but lowered SNeGFR/VglomNSG in CKD subjects, suggesting that changes in GFR are accommodated by glomerular hypertrophy rather than glomerular hypertension. These findings suggest glomerular hypertrophy is a dominant factor in maintenance of GFR under conditions of low nephron number.

APOL1 Risk Variants Independently Associated With Early Cardiovascular Disease Death

Introduction

The relationship of APOL1 renal risk variants to cardiovascular disease (CVD) is controversial and was the subject of this investigation.

Methods

Age, cause of death, and nephrosclerosis (the latter defined by glomerulosclerosis) were analyzed in the autopsies of 162 African Americans and 136 whites genotyped for APOL1 risk alleles.

Results

Sudden deaths represented >75% of CVD autopsies for both races and all-risk genotypes. The average ages of CVD deaths for African Americans with 1 and 2 APOL1 risk alleles were, respectively, 7.0 years (P = 0.02) and 12.2 years (P < 0.01) younger than African Americans with 0 risk alleles and 8.7 years (P = 0.01) and 13.9 years (P = 0.01) younger than whites. Age differences were not significant between African Americans and whites with 0 risk alleles (P = 0.61). The younger CVD deaths of African Americans were associated with less severe glomerulosclerosis with 2 (P = 0.01), although not 1 (P = 0.09), compared with 0 APOL1 risk alleles. Cardiomyopathy was found in 23% of African Americans with 1 and 2 risk alleles and significantly contributed to the lower age (P = 0.01). For non-CVD deaths, age differences were not seen by race (P = 0.28) or among African Americans by risk allele status (P = 0.38).

Conclusion

Carriage of 1 or 2 APOL1 risk alleles in African Americans was associated with earlier age deaths due to coronary artery disease and cardiomyopathy. For 2 risk alleles, the early age was independent of nephrosclerosis.

Breast cancer in Iraq is associated with a unimodally distributed predominance of luminal type B over luminal type A surrogates from young to old age

BACKGROUND

Breast cancer has recently increased in post-menopausal Iraqi women. In Western countries at high-risk for breast cancer, there is a bimodal increase in estrogen receptor (ER) positive tumors with a peak of low proliferation rate luminal A over higher proliferation rate luminal B tumors after 60 years of age. The aim of this study was to analyze in Iraqi women whether shifts are occurring in immunohistochemical (IHC) surrogates of molecular breast cancer subtypes toward a high-risk profile.

METHODS

Age specific and age standardized womens breast cancer incidence was estimated for the years 2006 through 2012. IHC results of ER, PR, HER2, and Ki67 testing were analyzed on the breast cancers of 125 Arabic and 725 Kurdish women by frequency of distribution and by age.

RESULTS

Between 2006 and 2012, age standardized incidence of breast cancer in Iraq increased from 30 to 40/100,000 women with the increase specifically occurring in women ≥ 60 years old (P < 0.001). Breast cancers in Kurdish women ≥ 60 years old may also have increased (P = 0.047) with urban exceeding rural rates by 2:1. For both Kurdish and Arabic women, there was a marked predominance of luminal B tumors at all ages in which luminal B and luminal A tumors were asymmetric skewed toward older age but with no late luminal A age peak.

CONCLUSIONS

Older Iraqi women do not show the bimodal shift toward higher rates of luminal A breast cancers seen in the West. The modest increase in age standardized incidence of breast cancer in Iraqi is being seen specifically in older women and may be better attributed to a trend for care in urban cancer centers rather than changing tumor characteristics.

APOL1 Risk Alleles are Associated with More Severe Arteriosclerosis in Renal Resistance Vessels with Aging and Hypertension

Introduction

The increased risk of end-stage kidney disease among hypertensive African Americans is partly related to APOL1 allele variants. The initial glomerulosclerosis of hypertension-associated arterionephrosclerosis consists of focal global glomerulosclerosis, but in biopsy studies, focal segmental glomerulosclerosis is found with progression to end-stage kidney disease, particularly in African Americans.

Methods

This is a study of arterionephrosclerosis in successfully APOL1-genotyped autopsy kidney tissue of 159 African Americans and 135 whites aged 18 to 89 years from a general population with no clinical renal disease.

Results

Glomerulosclerosis was nearly exclusively focal global glomerulosclerosis with 3 subjects having focal segmental glomerulosclerosis–like lesions that were unrelated to APOL1 risk status. For both races, in multivariable analysis, the dependent variables of arteriosclerosis and glomerulosclerosis were significantly related to the independent variables of older age (P < 0.001) and hypertension (P < 0.001). A relationship between APOL1 genotype and arteriosclerosis was apparent only after 35 years of age, when, for any level of elevated blood pressure, more severe arteriosclerosis was found in the interlobular arteries of 14 subjects with 2 APOL1 risk alleles compared to African Americans with none (n = 37, P = 0.02) or 1 risk allele (n = 35, P = 0.02).

Discussion

With the limitation of the small number of subjects contributing to the positive results, the findings imply that APOL1 risk alleles recessively augment small-vessel arteriosclerosis in conjunction with age and hypertension. Focal segmental glomerulosclerosis was not a significant finding, indicating that in the early stages of arterionephrosclerosis, the primary pathologic influence of APOL1 genotype is vascular rather than glomerular.

Human podocyte depletion in association with older age and hypertension

Podocyte depletion plays a major role in the development and progression of glomerulosclerosis. Many kidney diseases are more common in older age and often coexist with hypertension. We hypothesized that podocyte depletion develops in association with older age and is exacerbated by hypertension. Kidneys from 19 adult Caucasian American males without overt renal disease were collected at autopsy in Mississippi. Demographic data were obtained from medical and autopsy records. Subjects were categorized by age and hypertension as potential independent and additive contributors to podocyte depletion. Design-based stereology was used to estimate individual glomerular volume and total podocyte number per glomerulus, which allowed the calculation of podocyte density (number per volume). Podocyte depletion was defined as a reduction in podocyte number (absolute depletion) or podocyte density (relative depletion). The cortical location of glomeruli (outer or inner cortex) and presence of parietal podocytes were also recorded. Older age was an independent contributor to both absolute and relative podocyte depletion, featuring glomerular hypertrophy, podocyte loss, and thus reduced podocyte density. Hypertension was an independent contributor to relative podocyte depletion by exacerbating glomerular hypertrophy, mostly in glomeruli from the inner cortex. However, hypertension was not associated with podocyte loss. Absolute and relative podocyte depletion were exacerbated by the combination of older age and hypertension. The proportion of glomeruli with parietal podocytes increased with age but not with hypertension alone. These findings demonstrate that older age and hypertension are independent and additive contributors to podocyte depletion in white American men without kidney disease.

APOL1 Risk Alleles Are Associated with Exaggerated Age-Related Changes in Glomerular Number and Volume in African-American Adults: An Autopsy Study

APOL1 genetic variants contribute to kidney disease in African Americans. We assessed correlations between APOL1 profiles and renal histological features in subjects without renal disease. Glomerular number (N glom) and mean glomerular volume (V glom) were measured by the dissector/fractionator method in kidneys of African-American and non-African-American adults without renal disease, undergoing autopsies in Jackson, Mississippi. APOL1 risk alleles were genotyped and the kidney findings were evaluated in the context of those profiles. The proportions of African Americans with none, one, and two APOL1 risk alleles were 38%, 43%, and 19%, respectively; 38% of African Americans had G1 allele variants and 31% of African Americans had G2 allele variants. Only APOL1-positive African Americans had significant reductions in N glom and increases in V glom with increasing age. Regression analysis predicted an annual average loss of 8834 (P=0.03, sex adjusted) glomeruli per single kidney over the first 38 years of adult life in African Americans with two risk alleles. Body mass index above the group medians, but below the obesity definition of ≥ 30 kg/m(2), enhanced the expression of age-related changes in N glom in African Americans with either one or two APOL1 risk alleles. These findings indicate that APOL1 risk alleles are associated with exaggerated age-related nephron loss, probably decaying from a larger pool of smaller glomeruli in early adult life, along with enlargement of the remaining glomeruli. These phenomena might mark mechanisms of accentuated susceptibility to kidney disease in APOL1-positive African Americans.

Acute kidney injury associated with androgenic steroids and nutritional supplements in bodybuilders(†)

Four bodybuilders who injected anabolic steroids and ingested commercial protein (78–104 g/day) and creatine (15 g/day) products presented with serum creatinine levels between 229.84 and 335.92 µmol/L (2.6–3.8 mg/dL). Renal biopsies revealed acute tubular necrosis. Four weeks after discontinuing injections and supplements, serum creatinine was in the normal range and estimated glomerular filtration rate > 1.00 mL/s (60 mL/min), including two patients with biopsies showing >30% interstitial fibrosis and tubular atrophy. The findings highlight a risk for acute and potentially chronic kidney injury among young men abusing anabolic steroids and using excessive amounts of nutritional supplements.

Podocyte Number in Children and Adults: Associations with Glomerular Size and Numbers of Other Glomerular Resident Cells

Increases in glomerular size occur with normal body growth and in many pathologic conditions. In this study, we determined associations between glomerular size and numbers of glomerular resident cells, with a particular focus on podocytes. Kidneys from 16 male Caucasian-Americans without overt renal disease, including 4 children (≤3 years old) to define baseline values of early life and 12 adults (≥18 years old), were collected at autopsy in Jackson, Mississippi. We used a combination of immunohistochemistry, confocal microscopy, and design-based stereology to estimate individual glomerular volume (IGV) and numbers of podocytes, nonepithelial cells (NECs; tuft cells other than podocytes), and parietal epithelial cells (PECs). Podocyte density was calculated. Data are reported as medians and interquartile ranges (IQRs). Glomeruli from children were small and contained 452 podocytes (IQR=335-502), 389 NECs (IQR=265-498), and 146 PECs (IQR=111-206). Adult glomeruli contained significantly more cells than glomeruli from children, including 558 podocytes (IQR=431-746; P<0.01), 1383 NECs (IQR=998-2042; P<0.001), and 367 PECs (IQR=309-673; P<0.001). However, large adult glomeruli showed markedly lower podocyte density (183 podocytes per 10(6) µm(3)) than small glomeruli from adults and children (932 podocytes per 10(6) µm(3); P<0.001). In conclusion, large adult glomeruli contained more podocytes than small glomeruli from children and adults, raising questions about the origin of these podocytes. The increased number of podocytes in large glomeruli does not match the increase in glomerular size observed in adults, resulting in relative podocyte depletion. This may render hypertrophic glomeruli susceptible to pathology.

Glomerular hypertrophy in subjects with low nephron number: contributions of sex, body size and race

BACKGROUND

We have shown that low nephron number (Nglom) is a strong determinant of individual glomerular volume (IGV) in male Americans. However, whether the same pattern is present in female Americans remains unclear. The contributions of body surface area (BSA) and race to IGV in the context of Nglom also require further evaluation.

METHODS

Kidneys without overt renal disease were collected at autopsy in Mississippi, USA. The extremes of female Nglom were used to define high and low Nglom for both sexes. Nglom and IGV were estimated by design-based stereology. A total of 24 African and Caucasian American females (n = 12 per race; 6 per Nglom extreme) were included. These subjects were subsequently matched to 24 comparable males by age and Nglom and to 18 additional males by age, Nglom and BSA.

RESULTS

IGV average and variance were very similar in female African and Caucasian Americans with high and low Nglom. Males with low Nglom from both races showed greater IGV average and variance than comparable females matched by age and Nglom. These differences in IGV between sexes were not observed in Caucasian Americans with low Nglom that were matched by age, Nglom and BSA. In contrast, glomeruli from African Americans were larger than those from Caucasian Americans, especially in subjects with high Nglom.

CONCLUSIONS

While female Americans with low Nglom did not show glomerular hypertrophy, comparable males with low Nglom showed marked glomerular hypertrophy that was closely associated with high BSA. Glomerular size in African Americans may be confounded by multiple additional factors.

Hypertension, glomerular hypertrophy and nephrosclerosis: the effect of race

Background

African Americans have more severe hypertensive nephrosclerosis than white Americans, possibly at similar levels of blood pressure. Glomerular volume is increased in African Americans relative to whites, but it is uncertain how this relates to nephrosclerosis and whether it contributes to or compensates for glomerulosclerosis.

Methods

Stereological disector/fractionator estimates of glomerular number (N_glom) and average glomerular volume (V_glom) were obtained on autopsy kidneys of 171 African Americans and 131 whites. Eighty-eight African Americans and 49 whites were identified as hypertensive. Nephrosclerosis was measured morphometrically as the percentage of glomerulosclerosis, proportion of cortical fibrosis and interlobular artery intimal thickness, and analyzed with V_glom by age, race, gender, body mass index (BMI) and blood pressure.

Results

African Americans were more frequently hypertensive (58.5%) than whites (35.8%) and when hypertensive had higher levels of blood pressure (P = 0.02). N_glom was significantly lower in hypertensive compared with non-hypertensive subjects among white women (P = 0.02) but not white males (P = 0.34) or African American females (P = 0.10) or males (P = 0.41). For each race and gender, glomerulosclerosis, cortical fibrosis and arterial intimal thickening were statistically correlated with age (P < 0.001) and hypertension (P < 0.001) and increased V_glom with hypertension (P < 0.001) and BMI (P < 0.001). In multivariate analysis, African American race was associated with increased V_glom (P = 0.01) and arterial intimal thickening (P < 0.01), while interactions between race and blood pressure indicated that the severity of nephrosclerosis including increased V_glom was linked most directly to hypertension without significant contributions from race. The hypertension-associated enlargement of V_glom was present with mild degrees of glomerulosclerosis and changed little as the severity of glomerulosclerosis increased.

Conclusions

Glomerular hypertrophy was identified as an integral feature of hypertensive nephropathy and appeared to precede rather than compensate for glomerulosclerosis. An effect of race on V_glom and arterial intimal thickening seemed to be related to the more frequent and more severe hypertension among African Americans.

Design-based stereological methods for estimating numbers of glomerular podocytes

The podocyte depletion hypothesis has emerged as a unifying concept in glomerular pathology. According to this hypothesis podocyte depletion may be absolute (decrease in number of healthy mature podocytes), relative (fewer podocytes per unit of glomerular volume) or involve alterations to the specialized podocyte architecture (such as foot process effacement). To study and understand podocyte depletion it is important to be able to accurately and precisely count these cells. Here we present new design-based stereological methods for estimating podocyte number in individual glomeruli of known volume, and in average glomeruli. Both methods involve serial histological sectioning, triple label immunohistochemistry, laser confocal microscopy and cell counting with the optical disector/fractionator.

Eosinophilic granulomatous gastrointestinal and hepatic abscesses attributable to basidiobolomycosis and fasciolias: a simultaneous emergence in Iraqi Kurdistan

Background

Deep eosinophilic granulomatous abscesses, as distinguished from eosinophilic subcutaneous abscesses, are rare. Most reports are from the Far-East and India where the most commonly attributed cause is Toxocara. Sulaimaniyah in Northeastern Iraq has experienced an outbreak of eosinophilic granulomatous liver and gastrointestinal (GI) abscesses beginning in 2009. The purpose of this study was to determine the etiology and guide treatment.

Methods

The study was an ongoing investigation of patients having a histopathologic diagnosis of eosinophilic granulomatous abdominal abscesses in Sulaimaniyah hospitals from May 2009 to August 2012. Tissues were examined for organisms, and Enzyme Linked Immunoabsorbent Assays (ELISA) were performed for serum antibodies to Fasciola hepatica, Toxocara, and Echinococcus granulosus.

Results

Fourteen patients had granulomatous inflammation surrounding a central necrotizing eosinophilic exudate identified in surgical pathology specimens from abdominal surgeries. Two children and four adults had abscesses that formed GI masses. These patients included a 39 year old male with oropharyngeal and transverse colon disease, and a 48 year old male with liver and GI abscesses. All sites demonstrated a Zygomycete fungus surrounded by eosinophilic Splendori-Hoeppli material consistent with basidiobolomycosis. Five of the six patients with fungal disease were treated by surgery and 4 to 7 months of itraconozol. One child died of intestinal perforation while receiving IV amphotericin B; two adults required additional surgery for recurrent GI obstruction. Eight patients had isolated liver abscesses with no organisms identified by histopathology: ELISA results for F. hepatica were positive for five, borderline for one, and negative for two patients. These eight patients were treated for fascioliasis by surgical resection of localized abscesses and albendazol. One patient serologically positive for F. Hepatica was found to have a common duct fluke two years after initial diagnosis. Serological testing for Toxocara and Echinococcus granulosus was negative in all 14 patients.

Conclusions

Basidiobolomycosis and F. hepatica are implicated as the cause of abdominal eosinophilic granulomatous abscesses in 12 of 14 patients identified over a period of 40 months in northern Iraq. Treatment was complicated by chronic biliary tract disease in fascioliasis and perforation and recurrent intestinal obstruction with basidiobolomycosis.

Estimating individual glomerular volume in the human kidney: clinical perspectives

BACKGROUND

Measurement of individual glomerular volumes (IGV) has allowed the identification of drivers of glomerular hypertrophy in subjects without overt renal pathology. This study aims to highlight the relevance of IGV measurements with possible clinical implications and determine how many profiles must be measured in order to achieve stable size distribution estimates.

METHODS

We re-analysed 2250 IGV estimates obtained using the disector/Cavalieri method in 41 African and 34 Caucasian Americans. Pooled IGV analysis of mean and variance was conducted. Monte-Carlo (Jackknife) simulations determined the effect of the number of sampled glomeruli on mean IGV. Lin's concordance coefficient (R(C)), coefficient of variation (CV) and coefficient of error (CE) measured reliability.

RESULTS

IGV mean and variance increased with overweight and hypertensive status. Superficial glomeruli were significantly smaller than juxtamedullary glomeruli in all subjects (P < 0.01), by race (P < 0.05) and in obese individuals (P < 0.01). Subjects with multiple chronic kidney disease (CKD) comorbidities showed significant increases in IGV mean and variability. Overall, mean IGV was particularly reliable with nine or more sampled glomeruli (R(C) > 0.95, <5% difference in CV and CE). These observations were not affected by a reduced sample size and did not disrupt the inverse linear correlation between mean IGV and estimated total glomerular number.

CONCLUSIONS

Multiple comorbidities for CKD are associated with increased IGV mean and variance within subjects, including overweight, obesity and hypertension. Zonal selection and the number of sampled glomeruli do not represent drawbacks for future longitudinal biopsy-based studies of glomerular size and distribution.

Human nephron number: implications for health and disease

Several studies have shown that total nephron (glomerular) number varies widely in normal human kidneys. Whereas the studies agree that average nephron number is approximately 900,000 to 1 million per kidney, numbers for individual kidneys range from approximately 200,000 to >2.5 million. Several studies have shown loss of glomeruli due to age-related glomerulosclerosis. The rates of loss vary among individuals depending upon blood pressure, diseases affecting the kidney, and other attributes of health, but most of the variation in nephron number is present at birth and is therefore developmentally determined. For example, in a relatively small study of nephron number in 15 children <3 months of age, we found that nephron number ranged from approximately 250,000 to 1.1 million. Given that no new nephrons are formed in human kidneys after approximately 36 weeks' gestation, much interest has focused on renal function and health in individuals born with relatively low nephron endowment. Several studies have reported a direct correlation between birth weight and nephron number and an indirect association between nephron number and blood pressure. Associations between low birth weight and cardiovascular disease, including hypertension, have also been widely reported. This report provides an update on our current knowledge of human nephron number and the associations with adult health and disease.

Distribution of volumes of individual glomeruli in kidneys at autopsy: association with physical and clinical characteristics and with ethnic group

We have demonstrated considerable variability in the volumes of different glomeruli in given individuals (individual glomerular volume: IGV) in a stereologic study of kidneys at forensic autopsy performed to investigate sudden or unexpected death in people without manifest kidney disease. We review some important associations of IGV by subject characteristics and by ethnic groups. IGVs were measured by the Cavalieri method in 30 glomeruli in each of 111 adult males who belonged to 4 ethnic groups, i.e. US Whites, African-Americans, Africans from Senegal, and Australian Aborigines. Correlations of pooled IGV values with certain subject characteristics were evaluated in the US Whites. Pooled IGV data were compared in subjects across the 4 ethnic groups. In US Whites, mean IGV and its variance were greater with higher age, lower nephron number, lower birth weight, and with gross obesity, hypertension and cardiovascular death. In comparisons by ethnic group, mean IGV and IGV ranges were higher in African-Americans and Australian Aborigines than in US Whites and African Senegalese subjects. We conclude that glomerular enlargement with volume heterogeneity marks more advanced age, relative nephron deficiency, lower birth weight, obesity, hypertension, and advanced cardiovascular disease. The findings in African-Americans and Australian Aborigines suggest that larger IGVs and volume heterogeneity might mark populations with accentuated susceptibility to hypertension and kidney disease, but the data need to be further examined in the context of the determining characteristics defined in the US Whites.

Towards a definition of glomerulomegaly: clinical-pathological and methodological considerations

BACKGROUND

Glomerulomegaly, the abnormal enlargement of glomeruli, has been related to an increased risk of glomerulosclerosis, but the degree of enlargement that constitutes glomerulomegaly has not been defined.

METHODS

The principal stereological methods for estimating glomerular volume are [1] the disector/Cavalieri method that is considered the 'gold standard' for measuring individual glomerular volume (IV(glom)) and [2] the disector/fractionator technique that estimates average glomerular volume (V(glom)) together with total glomerular number (N(glom)) for the entire kidney. The two methods produce different estimates with V(glom) consistently exceeding IV(glom). This study compares glomerular volumes obtained by the two methods in autopsy kidneys of 39 African American and 34 US white adult males, and correlates the values with N(glom), body mass index (BMI), hypertension, glomerulosclerosis and race, factors known or thought to influence glomerular volume.

RESULTS

For the smallest glomeruli, V(glom) was 25% larger than IV(glom) with the difference increasing to over 50% for kidneys with the largest glomeruli. Both V(glom) and IV(glom) showed significant inverse correlations with N(glom) and significant direct correlations with BMI and hypertension. African Americans had larger IV(glom) and V(glom) than whites, but only IV(glom) was significant. The 90th percentile for IV(glom) was 6.81 μm(3) × 10(6) and 13.10 μm(3) × 10(6) for V(glom), but larger glomerular size did not separate hypertensive from non-hypertensive subjects nor did it show any significant relationship to glomerulosclerosis. While V(glom) overestimated glomerular size compared with IV(glom), both measurements demonstrated similar relationships to factors influencing glomerular volume.

CONCLUSIONS

With neither method could glomerulomegaly, the abnormal enlargement of glomerular size predisposing to glomerulosclerosis, be determined.

A comparison of nephron number, glomerular volume and kidney weight in Senegalese Africans and African Americans

BACKGROUND

Low nephron number is determined in utero and is a proposed risk for essential hypertension. Glomerular volume is inversely correlated with nephron number, and genetic and environmental factors that determine nephron number are thought to determine glomerular volume. This study compared total glomerular (nephron) number (N(glom)), mean glomerular volume (V(glom)) and kidney weight in two geographically separated black populations with significant common genetic ancestry.

METHODS

Unbiased stereology was used to determine N(glom) and V(glom) in kidneys collected at coronial autopsy in an age- and sex-matched sample of 39 adult Africans from Dakar in Senegal, West Africa and 39 African Americans from Mississippi in the USA.

RESULTS

African Americans were taller and heavier than their Senegalese counterparts. N(glom) was remarkably similar-with a geometric mean of 937 967 in Senegalese and 904 412 in African Americans (P = 0.62). V(glom) was correlated inversely with N(glom) and directly with body surface area in both groups, but V(glom) was 54% greater in African Americans than in Senegalese Africans [8.30 +/- 2.92 (SD) and 5.38 +/- 1.25 microm(3) x 10(6), respectively] and remained significantly larger (38%) after adjustment for body size. V(glom) increased with age in African Americans, but not in the Senegalese. Kidney weight was larger in African Americans (P < 0.0001), but kidney-to-body weight ratio was not different between groups.

CONCLUSIONS

Despite similar nephron numbers, a common genetic constitution, and even in relation to current body size, African Americans have larger V(glom) than Senegalese subjects. This may mark exposure to environmental stressors or hereditary traits concentrated in the population's relocation to North America.

Breast cancer in Kurdish women of northern Iraq: incidence, clinical stage, and case control analysis of parity and family risk

Background

Breast cancer in the Middle-East occurs in relatively young women and frequently presents as advanced disease. A protective effect of multiparity is not apparent, and high familial risk is reported in some countries. This study investigates breast cancer rates and clinical stage related to age in the Kurdish region of Iraq and evaluates risk associated with parity and family history. Findings are compared with nearby countries and the West.

Methods

Sulaimaniyah Directorate of Health records identified 539 women diagnosed with breast cancer during 2006-2008. Clinical survey forms were completed on 296 patients and on 254 age-matched controls. Age specific incidence rates were calculated from Directorate of Health population estimates.

Results

Average patient age was 47.4 ± 11 years and 59.5% were pre-menopausal. Diagnosis was at clinical stage 1 for 4.1%, stage 2 for 43.5%, stage 3 for 26.0%, and stage 4 for 8.1% of patients. For 18.2%, stage was unknown. Annual breast cancer incidence rates per 100,000 women peaked at 168.9 at age 55 to 59 and declined to 57.3 at 60 and above. Patients had an average of 5.0 ± 3.3 children compared to 5.4 ± 3.5 for controls, P = 0.16. A first degree family member had breast cancer among 11.1% of patients and 2.1% of controls (P < 0.001) with > 50% of these patients and controls being ≥50 years old. No statistically significant relationship was found between tumor stage and age, P = 0.59.

Conclusions

In Kurdish Iraq, breast cancer is predominantly a disease of pre-menopausal women having multiple pregnancies. For younger patients, breast cancer incidence was similar to the West and possibly higher than many Middle-Eastern countries, but unlike the West, the estimated rates declined markedly in the elderly. The familial breast cancer risk for both older and younger women was within the general population risk of Western countries. Clinical stages were advanced and indicated delays in diagnosis that were unrelated to patient age.

Nephron number and individual glomerular volumes in male Caucasian and African American subjects

BACKGROUND

Glomerular hypertrophy has been described in several populations at high risk of chronic kidney disease. Total nephron (and thereby glomerular) number (N(glom)) varies widely in normal adult human kidneys and is generally inversely correlated with mean glomerular volume (V(glom)). However, little is known about the range of individual glomerular volumes (IV(glom)) within single human kidneys and the association with N(glom). The aim of the present study was to estimate IV(glom) in Caucasian and African Americans and identify any associations between heterogeneity in IV(glom) and nephron number.

METHODS

Using unbiased stereological techniques, IV(glom) was determined for 30 glomeruli in each of 24 adult male kidneys from Jackson, MS, USA (12 Caucasian and 12 African American). Half of each group had 'high' N(glom) (>1.2 million nephrons per kidney) and the other half had 'low' N(glom) (<600 000).

RESULTS

Caucasians with high N(glom) had a relatively homogeneous distribution of IV(glom) as well as a relatively low mean value, while those with low N(glom) had much greater heterogeneity of IV(glom), as well as a larger IV(glom) (P < 0.0001) compared with those with high N(glom). This disparity was not apparent in African Americans, however, where subjects with both high and low N(glom) showed substantial heterogeneity in IV(glom) and larger mean values (P = 0.95).

CONCLUSIONS

High N(glom) appeared to protect against glomerular enlargement and volume heterogeneity in Caucasians. However, substantial variation in IV(glom) and net enlargement in glomerular size in African Americans with high nephron numbers suggest that additional forces, independent of low N(glom), are driving glomerular enlargement and heterogeneity.

NADPH oxidase contributes to renal damage and dysfunction in Dahl salt-sensitive hypertension

The goal of this study was to test the hypothesis that NADPH oxidase contributes importantly to renal cortical oxidative stress and inflammation, as well as renal damage and dysfunction, and increases in arterial pressure. Fifty-four 7- to 8-wk-old Dahl salt-sensitive (S) or R/Rapp strain rats were maintained for 5 wk on a high sodium (8%) or high sodium + apocynin (1.5 mmol/l in drinking water). Arterial and venous catheters were implanted on day 21. By day 35 in the high-Na S rats, mRNA expression of renal cortical gp91phox, p22phox, p47phox, and p67phox NADPH subunits in S rats increased markedly, and treatment of high-Na S rats with the NADPH oxidase inhibitor apocynin resulted in significant decreases in mRNA expression of these NADPH oxidase subunits. At the same time, in apocynin-treated S rats 1) renal cortical GSH/GSSG ratio increased, 2) renal cortical O2(.-) release and NADPH oxidase activity decreased, and 3) renal glomerular and interstitial damage markedly fell. Apocynin also decreased renal cortical monocyte/macrophage infiltration, and apocynin, but not the xanthine oxidase inhibitor allopurinol, attenuated decreases in renal hemodynamics and lowered arterial pressure. These data suggest that NADPH oxidase plays an important role in causing renal cortical oxidative stress and inflammation, which lead to decreases in renal hemodynamics, renal cortical damage, and increases in arterial pressure.

Associations between age, body size and nephron number with individual glomerular volumes in urban West African males

BACKGROUND

Glomerulomegaly has been associated with an increased risk of renal disease. Few reports have investigated the heterogeneity of glomerular size within kidneys and associated risk factors. This study measured the individual glomerular volume (IGV) of 720 non-sclerotic glomeruli in kidneys of adult West African males, and investigated associations of IGV with age, total glomerular (nephron) number and body surface area (BSA).

METHODS

IGVs were determined in the kidneys of 24 Senegalese males from two age groups (12 subjects aged 20- 30 years and 12 subjects aged 50-70 years). Subjects were randomly chosen at autopsies performed at Le Dantec Hospital in Dakar. Volumes of 30 glomeruli per subject were determined using the disector/Cavalieri stereological method.

RESULTS

IGVs ranged from 1.31 x 10(6) microm3 to 12.40 x 10(6) microm3 (a 9.4-fold variation). IGV varied up to 5.3-fold within single kidneys. The trimmed range of IGV within subjects (10th to 90th percentile of IGV) was directly correlated with median glomerular size. The mean and standard deviation (SD) of IGV did not differ significantly between age groups or between subjects with higher (> or =1.78 m2) and lower BSA (<1.78 m2). In older subjects the SD of IGV was significantly and directly correlated with BSA. Kidneys with less than 1 million nephrons had significantly larger mean IGV than kidneys with more than 1 million nephrons, and the trimmed range of IGVs within subjects was inversely correlated with total glomerular number.

CONCLUSION

There was a considerable variation in IGV within kidneys of Senegalese males at autopsy. The heterogeneity of IGV was increased in association with low nephron number and increased BSA, with more pronounced effects in older subjects.

A common RET variant is associated with reduced newborn kidney size and function

Congenital nephron number varies five-fold among normal humans, and individuals at the lower end of this range may have an increased lifetime risk for essential hypertension or renal insufficiency; however, the mechanisms that determine nephron number are unknown. This study tested the hypothesis that common hypomorphic variants of the RET gene, which encodes a tyrosine kinase receptor critical for renal branching morphogenesis, might account for subtle renal hypoplasia in some normal newborns. A common single-nucleotide polymorphism (rs1800860 G/A) was identified within an exonic splicing enhancer in exon 7. The adenosine variant at mRNA position 1476 reduced affinity for spliceosome proteins, enhanced the likelihood of aberrant mRNA splicing, and diminished the level of functional transcript in human cells. In vivo, normal white newborns with an rs1800860(1476A) allele had kidney volumes 10% smaller and cord blood cystatin C levels 9% higher than those with the rs1800860(1476G) allele. These findings suggest that the RET(1476A) allele, in combination with other common polymorphic developmental genes, may account for subtle renal hypoplasia in a significant proportion of the white population. Whether this gene variant affects clinical outcomes requires further study.

Renal pathology, glomerular number and volume in a West African urban community

BACKGROUND

Low glomerular number and large glomerular volume are hypothesized to be risk factors for hypertensive renal disease in adult life. Reports of human glomerular number are based on studies from developed nations and have found single kidney mean values of approximately 900 000 per kidney with a roughly 8-fold range matched by a similar range in glomerular volume. Glomerular number and volume have never been investigated in people from a developing country.

METHODS

This study analysed the pathology of 81 autopsy kidneys from Dakar, Senegal, and determined total glomerular number and mean glomerular volume in 28 of these kidneys using the physical disector/fractionator method.

RESULTS

Total glomerular number ranged 2.6-fold from 536 171 to 1 394 010, with a mean of 925 485 nephrons. The mean glomerular volume was 5.74 microm(3) x 10(6) with a 2.5-fold variation that was strongly and inversely correlated with total glomerular number. Glomerular number was inversely correlated with age, and age-associated increases in arteriosclerosis, cortical fibrosis and glomerulosclerosis were observed. Arteriolar nephrosclerosis was observed in 34% of adults. Mean glomerular number in this Dakar population was similar to that previously reported for people from developed nations, while the range of glomerular number and mean glomerular volume was much narrower.

CONCLUSIONS

The frequency of arteriolar nephrosclerosis in these Senegalese adults was high (34%), suggesting that hypertensive kidney disease could contribute to a large burden of future chronic kidney disease in this population. Unusually low glomerular number or large glomerular volume do not appear to provide a basis for this potential burden of kidney disease.

Glomerular volume and clinicopathologic features related to disease severity in renal biopsies of African Americans and whites in the southeastern United States

CONTEXT

African Americans have a 4-fold greater risk than whites for developing end-stage renal disease. Glomerulomegaly, possibly related to obesity, has been identified in high-risk populations and is suggested to be a marker for end-stage renal disease risk.

OBJECTIVE

To investigate differences in glomerular size and patient clinical characteristics at the time of renal biopsy for the major diseases contributing to end-stage renal disease.

DESIGN

Mean glomerular tuft volumes were estimated by the Weibel-Gomez method (1964) in native renal biopsies of 203 African American and 100 white patients 18 years of age and older by point counting on a stereologic grid. Glomerulosclerosis was graded on individual glomeruli from 0 to 4, and a glomerular sclerosis index was calculated for each biopsy. Relationships between the mean volume of nonsclerotic glomeruli, age, sex, race, sclerosis index, cortical fibrosis, estimated glomerular filtration rate, body mass index, and disease diagnosis were analyzed.

RESULTS

Racial differences in mean volume of nonsclerotic glomeruli and body mass index were not significant in any disease category, and African Americans had more severe disease as determined by sclerosis index, cortical fibrosis, and estimated glomerular filtration rate only in focal segmental glomerulosclerosis. For all patients, increased sclerosis index and cortical fibrosis and lower estimated glomerular filtration rate were best predicted by increased age (P < .001).

CONCLUSIONS

For approximately the same severity of disease, African Americans were 10 years or more younger than whites with the difference being seen in all disease categories except membranous glomerulonephritis and diabetes. Glomerulomegaly relative to whites was not a distinguishing feature of African American renal biopsies.

Interactions between oxidative stress and inflammation in salt-sensitive hypertension

The goal of this study was to test the hypothesis that increases in oxidative stress in Dahl S rats on a high-salt diet help to stimulate renal nuclear factor-kappaB (NF-kappaB), renal proinflammatory cytokines, and chemokines, thus contributing to hypertension, renal damage, and dysfunction. We specifically studied whether antioxidant treatment of Dahl S rats on high Na intake would decrease renal inflammation and thus attenuate the hypertensive and adverse renal responses. Sixty-four 7- to 8-wk-old Dahl S or R/Rapp strain rats were maintained for 5 wk on high Na (8%) or high Na + vitamins C (1 g/l in drinking water) and E (5,000 IU/kg in food). Arterial and venous catheters were implanted at day 21. By day 35 in the high-Na S rats, antioxidant treatment significantly increased the renal reduced-to-oxidized glutathione ratio and decreased renal cortical H(2)O(2) and O(2)(*-) release and renal NF-kappaB. Antioxidant treatment with vitamins C and E in high-Na S rats also decreased renal monocytes/macrophages in the glomeruli, cortex, and medulla, decreased tumor necrosis factor-alpha by 39%, and decreased monocyte chemoattractant protein-1 by 38%. Vitamin-treated, high-Na S rats also experienced decreases in arterial pressure, urinary protein excretion, renal tubulointerstitial damage, and glomerular necrosis and increases in glomerular filtration rate and renal plasma flow. In conclusion, antioxidant treatment of high-Na Dahl S rats decreased renal inflammatory cytokines and chemokines, renal immune cells, NF-kappaB, and arterial pressure and improved renal function and damage.

Applicability of the glomerular size distribution coefficient in assessing human glomerular volume: the Weibel and Gomez method revisited

Changes in glomerular volume (V(glom)) play an important role in the initiation and progression of various glomerulopathies. Estimation of V(glom) in the normal kidney provides baseline values for studies of glomerular hypertrophy in disease. The traditional model-based method of Weibel and Gomez is widely applied to estimate V(glom) in clinical biopsy specimens. Assumptions of glomerular size distribution and shape required by this method are potential sources of bias that have not been verified. We evaluated the applicability of the glomerular size distribution coefficient in estimating V(glom) in human kidneys. V(glom) of 720 non-sclerotic glomeruli in histologically normal kidneys of 24 males (20-69 years) was estimated by the unbiased disector/Cavalieri approach. Accurate glomerular diameters were calculated from Cavalieri estimates of V(glom) assuming glomerular sphericity. The coefficients of variation (CV) of glomerular diameters were compared with the corresponding values of the size distribution coefficient predicted by the Weibel and Gomez method. Mean (SD) glomerular diameter was 201 (28) mm (range 110-276 mm). The CV of glomerular diameter within each kidney ranged from 4.9 to 14.6%. Corresponding glomerular size distribution coefficients predicted by the formula of Weibel and Gomez ranged from 1.00 to just 1.03. The value of the size distribution coefficient required by the Weibel and Gomez technique when estimating V(glom) in normal human kidneys is remarkably constant. This is despite large variations in V(glom). Future studies should examine the extent of bias introduced by the glomerular shape assumptions of this method.

Immune suppression prevents renal damage and dysfunction and reduces arterial pressure in salt-sensitive hypertension

The goal of this study was to test the hypothesis that renal infiltration of immune cells in Dahl S rats on increased dietary sodium intake contributes to the progression of renal damage, decreases in renal hemodynamics, and development of hypertension. We specifically studied whether anti-immune therapy, using mycophenolate mofetil (MMF), could help prevent increases in renal NF-κB activation, renal infiltration of monocytes/macrophages, renal damage, decreases in glomerular filtration rate (GFR) and renal plasma flow, and increases in arterial pressure. Seventy-four 7-to 8-wk-old Dahl S, Rapp strain rats were maintained on an 8% Na, 8% Na + MMF (20 mg·kg−1·day−1), 0.3% Na, or 0.3% Na + MMF diet for 5 wk. Arterial and venous catheters were implanted at day 21. By day 35, renal NF-κB in 8% Na rats was 47% higher than in 0.3% Na rats and renal NF-κB was 41% lower in 8% Na + MMF rats compared with the 8% Na group. MMF treatment significantly decreased renal monocyte/macrophage infiltration and renal damage and increased GFR and renal plasma flow. In high-NA Dahl S rats mean arterial pressure increased to 182 ± 5 mmHg, and MMF reduced this arterial pressure to 124 ± 3 mmHg. In summary, in Dahl S rats on high sodium intake, treatment with MMF decreases renal NF-κB and renal monocyte/macrophage infiltration and improves renal function, lessens renal injury, and decreases arterial pressure. This suggests that renal infiltration of immune cells is associated with increased arterial pressure and renal damage and decreasing GFR and renal plasma flow in Dahl salt-sensitive hypertension.

N-Acetylcysteine improves renal dysfunction, ameliorates kidney damage and decreases blood pressure in salt-sensitive hypertension

BACKGROUND

Salt-sensitive hypertension in humans and experimental animals causes progressive increases in renal damage and dysfunction. The Dahl salt-sensitive (S) rat closely mimics human salt-sensitive hypertension.

AIM

Our goal was to test the hypothesis that enhancing the glutathione system with dietary N-acetylcysteine administration in Dahl S rats on a high sodium intake for 5 weeks will attenuate the increases in arterial pressure, the decreases in renal hemodynamics and the increases in renal damage that normally occur in S rats on high sodium.

METHODS

Forty-four 7- to 8-week-old Dahl S/Rapp strain rats were maintained on a high sodium (8%), high sodium + N-acetylcysteine (4 g/kg per day), or low sodium (0.3%) diet for 5 weeks. Rats had arterial and venous catheters implanted at day 21.

RESULTS

By day 35 in the high-sodium rats, N-acetylcysteine treatment significantly increased the renal reduced-to-oxidized glutathione ratio, glomerular filtration rate, and renal plasma flow, and decreased renal cortical and medullary O2 release, urinary protein excretion, renal tubulointerstitial damage and glomerular necrosis. At this time, mean arterial pressure increased to 183 +/- 1 mmHg, and N-acetylcysteine reduced this arterial pressure to 121 +/- 4 mmHg. By day 35 in S high-sodium rats, N-acetylcysteine had caused a 91% decrease in glomerular necrosis and an 83% decrease in tubulointerstitial damage.

CONCLUSIONS

In Dahl S rats on high sodium intake, arterial pressure increases significantly and renal injury is pronounced. Treatment with N-acetylcysteine enhances the renal glutathione system, improves renal dysfunction and markedly decreases arterial pressure and renal injury in Dahl salt-sensitive hypertension.

A comparison of pathomolecular markers of fibrosis and morphology in kidney from autopsies of African Americans and whites

African Americans have an increased incidence of chronic kidney disease (CKD) due to hypertension and arteriosclerosis and increased death due to coronary artery disease, compared with whites. The pathogenesis of CKD involves the increased presence and activation of myofibroblasts and macrophages, promotion of tubulointerstitial fibrosis, and effects of tubulointerstitial cell mitosis and apoptosis. We hypothesized that increased risk of hypertensive vascular disease may be identified by renal pathomolecular markers that are associated with progressive CKD. Renal sections were available from 50 autopsies of 33 African Americans (55% males) and 17 whites (76% males) undergoing forensic autopsy for unexpected death. Sclerotic glomeruli, severity of cortical fibrosis, and renal arteriolosclerosis, total glomerular number (N (glom)), average glomerular volume (V (glom)), birth weights, and blood pressure were known. Presence and locality of markers for myofibroblasts (alpha-SMA), macrophages (CD68), collagen, pro-fibrotic transforming growth factor-beta1 were scored in renal autopsies, and tubulointerstitial apoptosis was recorded. The results demonstrated a strong positive correlation between age, cortical fibrosis and alpha-SMA (p<0.05), and between CD68 and hypertension and coronary artery disease (p<0.05). The findings confirm the role of myofibroblasts and macrophages in pathogenesis of human CKD. However, the markers showed no significant relationships to V (glom), N (glom), birth weight, or race.

Reduced nephron number and glomerulomegaly in Australian Aborigines: A group at high risk for renal disease and hypertension

Aborigines in remote areas of Australia have much higher rates of renal disease, as well as hypertension and cardiovascular disease, than non-Aboriginal Australians. We compared kidney findings in Aboriginal and non-Aboriginal people in one remote region. Glomerular number and mean glomerular volume were estimated with the disector/fractionator combination in the right kidney of 19 Aborigines and 24 non-Aboriginal people undergoing forensic autopsy for sudden or unexpected death in the Top End of the Northern Territory. Aborigines had 30% fewer glomeruli than non-Aborigines--202,000 fewer glomeruli per kidney, or an estimated 404,000 fewer per person (P=0.036). Their mean glomerular volume was 27% larger (P=0.016). Glomerular number was significantly correlated with adult height, inferring a relationship with birthweight, which, on average, is much lower in Aboriginal than non-Aboriginal people. Aboriginal people with a history of hypertension had 30% fewer glomeruli than those without--250,000 fewer per kidney (P=0.03), or 500,000 fewer per person, and their mean glomerular volume was about 25% larger. The lower nephron number in Aboriginal people is compatible with their susceptibility to renal failure. The additional nephron deficit associated with hypertension is compatible with other reports. Lower nephron numbers are probably due in part to reduced nephron endowment, which is related to a suboptimal intrauterine environment. Compensatory glomerular hypertrophy in people with fewer nephrons, while minimizing loss of total filtering surface area, might be exacerbating nephron loss. Optimization of fetal growth should ultimately reduce the florid epidemic of renal disease, hypertension, and cardiovascular disease.

How many glomerular profiles must be measured to obtain reliable estimates of mean glomerular areas in human renal biopsies?

The objective of this study was to investigate the number of glomerular profiles that are required for accurate estimates of mean profile area in a renal biopsy series. Slides from 384 renal biopsies from one center were reviewed. They contained a median of seven glomerular profiles or of four profiles without sclerosis. Profile areas were measured using stereologic point counting. The "true individual mean" for each biopsy was calculated and the "true population mean" for groups of biopsies derived. Individual and population "random sample means" then were calculated from a random sampling of profiles in each biopsy and were compared with true means for the same biopsies. The effect on the true population means of the entire group of biopsies was also assessed, as the minimum number of glomerular profiles that were required for inclusion was changed. In a single biopsy, random sampling of > or =10 profiles without exclusions and of eight profiles or more without sclerosis reliably estimated the true mean areas. In a group of 30 biopsies, random sampling of five or more glomeruli per biopsy reliably estimated the true population mean. In the aggregate series, inclusion of all 384 biopsies produced the most robust true population mean; the reliability of the estimates decreased as the numbers of eligible biopsies diminished with increasing requisite minimum numbers of profiles per biopsy. We conclude that, while > or =10 profiles might be needed for reliable area estimates in a single biopsy, far fewer profiles per biopsy can suffice when groups of biopsies are studied. In analyses of groups of biopsies, all available biopsies should be used without consideration of the number of glomerular profiles in each. Stipulation of a specific minimum number of glomeruli in each biopsy for inclusion reduces the power of analyses because fewer biopsies are available for evaluation.

Hypertension, glomerular number, and birth weight in African Americans and white subjects in the southeastern United States

Low nephron number has been related to low birth weight and hypertension. In the southeastern United States, the estimated prevalence of chronic kidney disease due to hypertension is five times greater for African Americans than white subjects. This study investigates the relationships between total glomerular number (Nglom), blood pressure, and birth weight in southeastern African Americans and white subjects. Stereological estimates of Nglom were obtained using the physical disector/fractionator technique on autopsy kidneys from 62 African American and 60 white subjects 30-65 years of age. By medical history and recorded blood pressures, 41 African Americans, and 24 white subjects were identified as hypertensive and 21 African Americans and 36 white subjects as normotensive. Mean arterial blood pressure (MAP) was obtained on 81 and birth weights on 63 subjects. For African Americans, relationships between MAP, Nglom, and birth weight were not significant. For white subjects, they were as follows: MAP and Nglom (r=-0.4551, P=0.0047); Nglom and birth weight (r=0.5730, P=0.0022); MAP and birth weight (r=-0.4228, P=0.0377). For African Americans, average Nglom of 961 840+/-292 750 for normotensive and 867 358+/-341 958 for hypertensive patients were not significantly different (P=0.285). For white subjects, average Nglom of 923 377+/-256 391 for normotensive and 754 319+/-329 506 for hypertensive patients were significantly different (P=0.03). The data indicate that low nephron number and possibly low birth weight may play a role in the development of hypertension in white subjects but not African Americans.

Does nephron number matter in the development of kidney disease?

The total number of nephrons in normal human kidneys varies over a 10-fold range. This variation in total nephron number leads us to question whether low nephron number increases the risk of renal disease in adulthood. This review considers the available evidence in humans linking low nephron number/reduced nephron endowment and the susceptibility to renal disease. Total nephron number in humans has been directly correlated with birth weight and inversely correlated with age, mean glomerular volume, and hypertension. Low nephron number may be the result of suboptimal nephrogenesis during kidney development and/or loss of nephrons once nephrogenesis has been completed. Low nephron number is frequently, but not always, associated with hypertrophy of remaining glomeruli. This compensatory hypertrophy has also been associated with a greater susceptibility for kidney disease. Three human studies have reported reduced nephron number in subjects with a history of hypertension. This correlation has been observed in White Europeans, White Americans (but not African Americans) and Australian Aborigines. Studies in additional populations are required, as well as a greater understanding of the fetal environmental and genetic determinants of low nephron number.

Determinants of glomerular volume in different cortical zones of the human kidney

Enlarged glomerular size is a feature of focal segmental glomerulosclerosis, obesity-related glomerulopathy, diabetic nephropathy, and hypertension. The distribution of glomerular volumes within different cortical zones and glomerular volume alterations with age and obesity may contribute to understanding the evolution of these diseases. We analyzed the distributions of volumes of individual glomeruli in the superficial, middle, and juxtamedullary cortex of normal human kidneys using the disector/Cavalieri method. Volumes (V(glom)) of 720 nonsclerotic glomeruli (30 per kidney, 10 per zone) were estimated in autopsy kidneys of 24 American men, 12 aged 20 to 30 yr and 12 aged 51 to 69 yr. Black and white individuals were represented equally. The range of individual V(glom) within subjects varied from two- to eight-fold. There were no significant zonal differences in V(glom) in the young or those with body surface area (BSA) < or = 2.11 m(2). In contrast, superficial glomeruli in the older age group, in those with BSA > 2.11 m(2), and in white subjects were significantly larger than juxtamedullary glomeruli. Black subjects tended toward larger V(glom) than white subjects, and this difference was significant and most marked in the juxtamedullary zone and independent of age, BSA, and glomerular number. There is a wide range in individual V(glom) in adults. BSA, race, and age independently influence V(glom) in different zones of the renal cortex. These findings might reflect processes of aging and susceptibility factors to renal disease.