Tuning Coherent-Phonon Heat Transport in LaCoO3/SrTiO3 Superlattices

Accessing the regime of coherent phonon propagation in nanostructures opens enormous possibilities to control the thermal conductivity in energy harvesting devices, phononic circuits, etc. In this paper we show that coherent phonons contribute substantially to the thermal conductivity of LaCoO₃/SrTiO₃ oxide superlattices, up to room temperature. We show that their contribution can be tuned through small variations of the superlattice periodicity, without changing the total superlattice thickness. Using this strategy, we tuned the thermal conductivity by 20% at room temperature. We also discuss the role of interface mixing and epitaxial relaxation as an extrinsic, material dependent key parameter for understanding the thermal conductivity of oxide superlattices.

Lipopolysaccharide Activates Toll-Like Receptor 4 and Prevents Cardiac Fibroblast-to-Myofibroblast Differentiation

Bacterial lipopolysaccharide (LPS) is a known ligand of Toll-like receptor 4 (TLR4) which is expressed in cardiac fibroblasts (CF). Differentiation of CF to cardiac myofibroblasts (CMF) is induced by transforming growth factor-β1 (TGF-β1), increasing alpha-smooth muscle actin (α-SMA) expression. In endothelial cells, an antagonist effect between LPS-induced signaling and canonical TGF-β1 signaling was described; however, it has not been studied whether in CF and CMF the expression of α-SMA induced by TGF-β1 is antagonized by LPS and the mechanism involved. In adult rat CF and CMF, α-SMA, ERK1/2, Akt, NF-κβ, Smad3, and Smad7 protein levels were determined by western blot, TGF-β isoforms by ELISA, and α-SMA stress fibers by immunocytochemistry. CF and CMF secrete the three TGF-β isoforms, and the secretion levels of TGF-β2 was affected by LPS treatment. In CF, LPS treatment decreased the protein levels of α-SMA, and this effect was prevented by TAK-242 (TLR4 inhibitor) and LY294002 (Akt inhibitor), but not by BAY 11-7082 (NF-κβ inhibitor) and PD98059 (ERK1/2 inhibitor). TGF-β1 increased α-SMA protein levels in CF, and LPS prevented partially this effect. In addition, in CMF α-SMA protein levels were decreased by LPS treatment, which was abolished by TAK-242. Finally, in CF LPS decreased the p-Smad3 phosphorylation and increased the Smad7 protein levels. LPS treatment prevents the CF-to-CMF differentiation and reverses the CMF phenotype induced by TGF-β1, through decreasing p-Smad3 and increasing Smad7 protein levels.

Factors associated with poor outcomes in patients with lupus nephritis

The objective of this study was to identify the factors associated with important clinical outcomes in a case-control study of 213 patients with lupus nephritis. Included were 47% Hispanics, 44% African Americans and 9% Caucasians with a mean age of 28 years. Fifty-four (25%) patients reached the primary composite outcome of doubling serum creatinine, end-stage renal disease or death during a mean follow-up of 37 months. Thirty-four percent African Americans, 20% Hispanics and 10% Caucasians reached the primary composite outcome ( P < 0.05). Patients reaching the composite outcome had predominantly proliferative lupus nephritis (WHO classes: 30% III, 32% IV, 18% V and 5% II, P < 0.025) with higher activity index score (7 ± 6 versus 5 ± 5, P<0.05), chronicity index (CI) score (4 ± 3 versus 2 ± 2 unit, P<0.025), higher baseline mean arterial pressure (MAP) (111 ± 21 versus 102 ± 14 mmHg, P<0.025) and serum creatinine (1.9 ± 1.3 versus 1.3 ± 1.0 mg/dL, P<0.025), but lower baseline hematocrit (29 ± 6 versus 31 + 5%, P<0.025) and complement C3 (54 ± 26 versus 65 + 33 mg/dL, P<0.025) compared to controls. More patients reaching the composite outcome had nephrotic range proteinuria compared to controls (74% versus 56%, P<0.025). By multivariate analysis, CI (hazard ratio [95% CI] 1.18 [1.07-1.30] per point), MAP (HR 1.02 [1.00-1.03] per mmHg), and baseline serum creatinine (HR 1.26 [1.04-1.54] per mg/dL) were independently associated with the composite outcome. We concluded that hypertension and elevated serum creatinine at the time of the kidney biopsy as well as a high CI are associated with an increased the risk for chronic renal failure or death in patients with lupus nephritis.

Single administration of recombinant IL-6 restores the gene expression of lipogenic enzymes in liver of fasting IL-6-deficient mice

BACKGROUND AND PURPOSE

Lipogenesis is intimately controlled by hormones and cytokines as well as nutritional conditions. IL-6 participates in the regulation of fatty acid metabolism in the liver. We investigated the role of IL-6 in mediating fasting/re-feeding changes in the expression of hepatic lipogenic enzymes.

EXPERIMENTAL APPROACH

Gene and protein expression of lipogenic enzymes were examined in livers of wild-type (WT) and IL-6-deficient (IL-6(-/-) ) mice during fasting and re-feeding conditions. Effects of exogenous IL-6 administration on gene expression of these enzymes were evaluated in vivo. The involvement of STAT3 in mediating these IL-6 responses was investigated by using siRNA in human HepG2 cells.

KEY RESULTS

During feeding, the up-regulation in the hepatic expression of lipogenic genes presented similar time kinetics in WT and IL-6(-/-) mice. During fasting, expression of lipogenic genes decreased gradually over time in both strains, although the initial drop was more marked in IL-6(-/-) mice. Protein levels of hepatic lipogenic enzymes were lower in IL-6(-/-) than in WT mice at the end of the fasting period. In WT, circulating IL-6 levels paralleled gene expression of hepatic lipogenic enzymes. IL-6 administration in vivo and in vitro showed that IL-6-mediated signalling was associated with the up-regulation of hepatic lipogenic enzyme genes. Moreover, silencing STAT3 in HepG2 cells attenuated IL-6 mediated up-regulation of lipogenic gene transcription levels.

CONCLUSIONS AND IMPLICATIONS

IL-6 sustains levels of hepatic lipogenic enzymes during fasting through activation of STAT3. Our findings indicate that clinical use of STAT3-associated signalling cytokines, particularly against steatosis, should be undertaken with caution.

Electronic Degeneracy and Intrinsic Magnetic Properties of EpitaxialNb: SrTiO3 Thin Films Controlled by Defects

We report thermoelectric power experiments in e-doped thin films of SrTiO3 (STO) which demonstrate that the electronic band degeneracy can be lifted through defect management during growth. We show that even small amounts of cationic vacancies, combined with epitaxial stress, produce a homogeneous tetragonal distortion of the films, resulting in a Kondo-like resistance upturn at low temperature, large anisotropic magnetoresistance, and nonlinear Hall effect. Ab initio calculations confirm a different occupation of each band depending on the degree of tetragonal distortion. The phenomenology reported in this Letter for tetragonally distorted e-doped STO thin films, is similar to that observed in LaAlO3/STO interfaces and magnetic STO quantum wells.

Impaired autophagic flux is associated with increased endoplasmic reticulum stress during the development of NAFLD

The pathogenic mechanisms underlying the progression of non-alcoholic fatty liver disease (NAFLD) are not fully understood. In this study, we aimed to assess the relationship between endoplasmic reticulum (ER) stress and autophagy in human and mouse hepatocytes during NAFLD. ER stress and autophagy markers were analyzed in livers from patients with biopsy-proven non-alcoholic steatosis (NAS) or non-alcoholic steatohepatitis (NASH) compared with livers from subjects with histologically normal liver, in livers from mice fed with chow diet (CHD) compared with mice fed with high fat diet (HFD) or methionine-choline-deficient (MCD) diet and in primary and Huh7 human hepatocytes loaded with palmitic acid (PA). In NASH patients, significant increases in hepatic messenger RNA levels of markers of ER stress (activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP)) and autophagy (BCN1) were found compared with NAS patients. Likewise, protein levels of GRP78, CHOP and p62/SQSTM1 (p62) autophagic substrate were significantly elevated in NASH compared with NAS patients. In livers from mice fed with HFD or MCD, ER stress-mediated signaling was parallel to the blockade of the autophagic flux assessed by increases in p62, microtubule-associated protein 2 light chain 3 (LC3-II)/LC3-I ratio and accumulation of autophagosomes compared with CHD fed mice. In Huh7 hepatic cells, treatment with PA for 8 h triggered activation of both unfolding protein response and the autophagic flux. Conversely, prolonged treatment with PA (24 h) induced ER stress and cell death together with a blockade of the autophagic flux. Under these conditions, cotreatment with rapamycin or CHOP silencing ameliorated these effects and decreased apoptosis. Our results demonstrated that the autophagic flux is impaired in the liver from both NAFLD patients and murine models of NAFLD, as well as in lipid-overloaded human hepatocytes, and it could be due to elevated ER stress leading to apoptosis. Consequently, therapies aimed to restore the autophagic flux might attenuate or prevent the progression of NAFLD.

Pivotal role of protein tyrosine phosphatase 1B (PTP1B) in the macrophage response to pro-inflammatory and anti-inflammatory challenge

Inhibition of protein tyrosine phosphatase 1B (PTP1B) has been suggested as an attractive target to improve insulin sensitivity in different cell types. In the present work, we have investigated the effect of PTP1B deficiency on the response of human and murine macrophages. Using in vitro and in vivo approaches in mice and silencing PTP1B in human macrophages with specific siRNAs, we have demonstrated that PTP1B deficiency increases the effects of pro-inflammatory stimuli in both human and rodent macrophages at the time that decreases the response to alternative stimulation. Moreover, the absence of PTP1B induces a loss of viability in resting macrophages and mainly after activation through the classic pathway. Analysis of early gene expression in macrophages treated with pro-inflammatory stimuli confirmed this exacerbated inflammatory response in PTP1B-deficient macrophages. Microarray analysis in samples from wild-type and PTP1B-deficient macrophages obtained after 24 h of pro-inflammatory stimulation showed an activation of the p53 pathway, including the excision base repair pathway and the insulin signaling pathway in the absence of PTP1B. In animal models of lipopolysaccharide (LPS) and D-galactosamine challenge as a way to reveal in vivo inflammatory responses, animals lacking PTP1B exhibited a higher rate of death. Moreover, these animals showed an enhanced response to irradiation, in agreement with the data obtained in the microarray analysis. In summary, these results indicate that, although inhibition of PTP1B has potential benefits for the treatment of diabetes, it accentuates pro-inflammatory responses compromising at least macrophage viability.

Magnetic field induced transition in vanadium spinels

We study vanadium spinels AV2O4 (A = Cd,Mg) in pulsed magnetic fields up to 65 T. A jump in magnetization at μ0H≈40  T is observed in the single-crystal MgV2O4, indicating a field induced quantum phase transition between two distinct magnetic orders. In the multiferroic CdV2O4, the field induced transition is accompanied by a suppression of the electric polarization. By modeling the magnetic properties in the presence of strong spin-orbit coupling characteristic of vanadium spinels, we show that both features of the field induced transition can be successfully explained by including the effects of the local trigonal crystal field.

Ab initio study of the influence of nanoscale doping inhomogeneities in the phase separated state of La1-xCaxMnO3

The chemical influence in the phase separation phenomenon that occurs in perovskite manganites is discussed by means of ab initio calculations. Supercells have been used to simulate a phase separated state, that occurs at Ca concentrations close to the localized itinerant crossover. We have first considered a model with two types of magnetic ordering coexisting within the same compound. This is not stable. However, a non-isotropic distribution of chemical dopants is found to be the ground state. This leads to regions in the system with different effective concentrations, that would always accompany the magnetic phase separation at the same nanometric scale, with hole-rich regions being more ferromagnetic in character and hole-poor regions being in the antiferromagnetic region of the phase diagram, as long as the system is close to a phase crossover.

Dirac point degenerate with massive bands at a topological quantum critical point

The quasilinear bands in the topologically trivial skutterudite insulator CoSb(3) are studied under adiabatic, symmetry-conserving displacement of the Sb sublattice. In this cubic, time-reversal and inversion symmetric system, a transition from trivial insulator to topological point Fermi surface system occurs through a critical point in which massless (Dirac) bands appear, and moreover are degenerate with massive bands. Spin-orbit coupling, while small due to the type of band character, coupled with tetragonal strain opens the gap required to give the topological insulator. The mineral skutterudite (CoSb(3)) is very near the critical point in its natural state.

Fermiology and magnetism in weak itinerant ferromagnet CoS2: an ab initio study

Electronic structure calculations have been performed on the compound CoS(2), an itinerant ferromagnet whose magnetic properties can be understood in terms of spin fluctuation theory. We have identified nesting features in the Fermi surface of the compound, active for long wavelength spin fluctuations. The electronic structure of the material is close to a half-metal. We show the importance of introducing spin-orbit coupling (SOC) in the calculations, which partially destroys the half-metallicity of the material. By means of transport properties calculations, we have quantified the influence of SOC in the conductivity at room temperature. Analyzing the effect of SOC helps in understanding the negative magnetoresistance of the material, whose conductivity varies within a few per cent with the introduction of small perturbations in the states around the Fermi level.

Review: Lupus nephritis: pathologic features, epidemiology and a guide to therapeutic decisions

Systemic lupus erythematosus may present with renal manifestations that frequently are difficult to categorize and lupus nephritis is an important predictor of poor outcome. The type and spectrum of renal injury may remain undiagnosed until full-blown nephritic and/or nephrotic syndrome appear with increased risk of end-stage renal disease. These abnormalities occur within the first few years after the diagnosis of lupus is made on clinical grounds and with the support of laboratory tests in high risk patients. An early renal biopsy is helpful in patients with an abnormal urinalysis and/or reduced glomerular filtration rate and the results form the basis for therapeutic decisions. The biopsy also provides vital prognostic information based on histological categorization of different types of lupus nephritis, the degree of activity, chronicity and the immunopathogenesis. In the current armamentarium, the use of cyclophosphamide and azathioprine and recently mycophenolate mofetil, reduce morbidity and maintenance therapies reduce the risk of end-stage renal disease. Clinical trials underway promise new, effective and safe immunosuppressive regimens for the treatment of proliferative lupus nephritis.

Tight-binding modeling and low-energy behavior of the semi-Dirac point

We develop a tight-binding model description of semi-Dirac electronic spectra, with highly anisotropic dispersion around point Fermi surfaces, recently discovered in electronic structure calculations of VO2-TiO2 nanoheterostructures. We contrast their spectral properties with the well-known Dirac points on the honeycomb lattice relevant to graphene layers and the spectra of bands touching each other in zero-gap semiconductors. We also consider the lowest order dispersion around one of the semi-Dirac points and calculate the resulting electronic energy levels in an external magnetic field. In spite of apparently similar electronic structures, Dirac and semi-Dirac systems support diverse low-energy physics.

Enhanced dimerization of TiOCl under pressure: spin-Peierls to Peierls transition

We report x-ray diffraction and magnetization measurements under pressure combined with ab initio calculations to show that high-pressure TiOCl corresponds to an enhanced Ti3+-Ti3+ dimerized phase existing already at room temperature. Our results demonstrate the formation of a metal-metal bond between Ti3+ ions along the b axis of TiOCl, accompanied by a strong reduction of the electronic gap. The evolution of the dimerization with pressure suggests a crossover from the spin-Peierls to a conventional Peierls situation at high pressures.

Homopolar bond formation in ZnV2O4 close to a metal-insulator transition

Electronic structure calculations for spinel vanadate ZnV2O4 show that partial electronic delocalization in this system leads to a structural instability, with the formation of V-V dimers along the [011] and [101] directions, and readily accounts for the intriguing magnetic structure of this material. The formation of V-V bonds is a consequence of the proximity to the itinerant-electron boundary and is not related to orbital ordering. We discuss how this mechanism naturally couples charge and lattice degrees of freedom in magnetic insulators close to such a crossover.

Enhanced pressure dependence of magnetic exchange in A2+[V2]O4 spinels approaching the itinerant electron limit

We report a systematic enhancement of the pressure dependence of T(N) in A(2+)[V(2)]O(4) spinels as the V-V separation approaches the critical separation for a transition to itinerant-electron behavior. An intermediate phase between localized and itinerant-electron behavior is identified in Zn[V(2)]O(4) and Mg[V(2)]O(4) exhibiting mobile holes as large polarons. Partial electronic delocalization, cooperative ordering of V-V pairs in Zn[V(2)]O(4) below T(s) approximately T(N) and dT(N)/dP<0, signals that lattice instabilities associated with the electronic crossover are a universal phenomenon.

Outcomes in African Americans and Hispanics with lupus nephritis

Poor outcomes have been reported in African Americans and Hispanics compared to Caucasians with lupus nephritis. The purpose of this retrospective analysis was to identify independent predictors of outcomes in African Americans and Hispanics with lupus nephritis. In total, 93 African Americans, 100 Hispanics, and 20 Caucasians with a mean age of 28 +/- 13 years and an annual household income of 32.9 +/- 17.3 (in 1000 US dollars) were studied. World Health Organization (WHO) lupus nephritis classes II, III, IV, and V were seen in 9, 13, 52, and 26%, respectively. Important baseline differences were higher mean arterial pressure (MAP) in African Americans compared to Hispanics and Caucasians (107 +/- 19, 102 +/- 15, and 99 +/- 13 mmHg, P < 0.05), and higher serum creatinine (1.66 +/- 1.3, 1.25 +/- 1.0, and 1.31 +/- 1.0 mg/dl, P < 0.025). African Americans had lower hematocrit compared to Hispanics and Caucasians (29 +/- 5, and 31 +/- 6, and 32 +/- 7%, P < 0.05), and lower annual household income (30.8 +/- 14.9, 33.1 +/- 15.9, and 42.2 +/- 29.3 in 1000 US dollars; P < 0.05). Lower prevalence of WHO class IV was seen in Caucasians (30%) compared to Hispanics (57%, P = 0.03) and African Americans (51%, P = 0.09). Development of doubling creatinine or end-stage renal disease was higher in African Americans and Hispanics than in Caucasians (31, 18, and 10%; P < 0.05), as was the development of renal events or death (34, 20, and 10%; P < 0.025). Our results suggest that both biological factors indicating an aggressive disease and low household income are common in African Americans and Hispanics with lupus nephritis, and outcomes in these groups are worse than in Caucasians.

Lupus nephritis: a clinical review for practicing nephrologists

The renal manifestations in systemic lupus erythematosus (SLE) are protean and difficult to categorize into clinical syndromes and histologic classes. Lupus nephritis is frequently unrecognized until full-blown nephritic and/or nephrotic syndrome with renal failure emerge. Epidemiologically, approximately one third of SLE patients from unselected populations have renal involvement early during the disease. Most renal abnormalities emerge within the first few years of SLE diagnosis. Currently, most nephrologists agree that an early renal biopsy is worthwhile in those SLE patients with abnormal urinalysis and/or reduced renal function. First, it provides a histologic categorization of the glomerulonephritis as well as an assessment of the degree of activity and chronicity. Second, it provides vital prognostic information. Third, it is beneficial in planning a more rational therapy with or without potentially toxic immunosuppressive agents. Over the last 3 decades, many controlled clinical trials for treatment of lupus nephritis have been completed with a few therapeutic immunosuppressive regimens. Among those agents used. cyclophosphamide and azathioprine provide a reduction of morbidity in those patients afflicted with proliferative forms of lupus glomerulonephritis. A new immunosuppressive agent, mycophenolate mofetil, is being studied for treatment of proliferative forms of lupus glomerulonephritis in a controlled clinical trial at our institution. Immunosuppressive agents and the availability of dialysis and transplantation have improved the survival of patients with lupus nephritis, in particular those with proliferative forms.

Nephrotic syndrome in autosomal dominant polycystic kidney disease

Urinary protein excretion is generally less than 1 g/24 h in autosomal dominant polycystic kidney disease (ADPKD), and the association of the nephrotic syndrome with this condition is considered rare. A patient with ADPKD associated with nephrotic-range proteinuria is described. She exhibited a relatively rapid impairment of her renal function. An open renal biopsy revealed focal segmental glomerulosclerosis (FGS) with features consistent with secondary FGS. Twenty-one patients with ADPKD and nephrotic syndrome were retrieved from the literature. Fourteen of them (including this case) had a histopathologic evaluation, and FGS was the dominant diagnoses (five patients). Next in frequency were minimal-change disease and membranous nephropathy, with two patients each. Five other patients had a variety of diagnoses. Thus, it is difficult to ascertain if these associations are coincidental or represent a specific pathogenetic relationship. The evaluation of the data also suggests that the presence of proteinuria and nephrotic syndrome accelerates the course of ADPKD toward ESRD.

Insulin reverses the protection given by diabetes against gentamicin nephrotoxicity in the rat

Rats with untreated diabetes mellitus are protected from gentamicin-induced nephrotoxicity. In order to evaluate the role of hyperglycemia, glycosuria, and polyuria in this phenomenon, miniosmotic pumps filled with insulin were implanted for 15 days in seven female Sprague-Dawley rats with streptozotocin-induced diabetes mellitus. Plasma glucose levels were successfully maintained under 126 mg/dl. To serve as the control group, eight age-matched diabetic (plasma glucose > 400 mg/dl) rats had miniosmotic pumps placed delivering only Ringer's solution. Six days after placement of the pumps, gentamicin (40 mg/Kg/day) was administered to all animals for 9 days. The insulin-treated diabetic rats exhibited clear signs of nephrotoxicity by Day 6 of gentamicin, whereas the diabetic control group remained free from any functional or morphological evidence of proximal tubular damage throughout the 9 days of the aminoglycoside administration. At the end of the experiment, the creatinine clearance in the insulin-treated diabetic group was 45% lower than in the untreated diabetic group (P < 0.005). In addition, there was a rise in plasma creatinine (P < 0.02), muramidase appeared in the urine, and mild patchy acute tubular necrosis of the renal cortex was observed by light microscopic examination. The insulin-treated group also accumulated more gentamicin in the renal cortex than the untreated animals (P < 0.005). It is concluded that protection against the nephrotoxic effects of gentamicin is a feature of untreated experimental diabetes mellitus in the rat and that correction of the hyperglycemic state with insulin reverses this resistance.

Human immunodeficiency virus nephropathy

Varying components of the syndrome of human immunodeficiency virus nephropathy (HIVN) have been described, the most pertinent including proteinuria/nephrotic syndrome, progressive azotemia, normal blood pressure, enlarged and hyperechoic kidneys, rapid progression to end-stage renal disease (ESRD), and no response to treatment regimens. The diagnosis of HIVN requires identification of excessive proteinuria or albuminuria, determined by a total protein excretion on a timed urine collection or a high protein/creatinine ratio in a random specimen. Various pathological lesions have been found in HIVN. The lesion of focal and segmental sclerosis (FS/FSS) is most characteristic in adults and usually is associated with a rapid demise. FS/FSS also has been described in approximately one-half of the pediatric patients reported in the literature (31/64). Despite progression to ESRD, the clinical course in children with HIVN is less fulminant than in adults. Other reported histological findings include primarily mesangial hyperplasia as well as minimal change, focal necrotizing glomerulonephritis or lupus nephritis, and hemolytic uremic syndrome. In addition to glomerular pathology, interstitial findings of dilated tubules filled with a unique proteinaceous material, atrophied tubular epithelium, and interstitial cell infiltration are very common. On electron microscopy, most investigators have found tubuloreticular inclusion bodies in endothelial cells of glomerular capillaries. Treatment of patients who develop ESRD remains highly controversial. Most adult patients treated with hemodialysis have succumbed rapidly; peritoneal dialysis has been better tolerated. Transplantation in patients with HIV infection must be considered to be tentative, with reports of acceleration towards full blown acquired immunodeficiency syndrome in some and uneventful 5-year survival in others.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous detection of ferritin and HIV-1 in reactive microglia

Using ferritin as a marker of reactive microglia, we demonstrated a close association between proliferation of reactive microglia and expression of human immunodeficiency virus type 1 (HIV-1) in brain tissue from autopsied cases of acquired immunodeficiency syndrome (AIDS). An increased number of ferritin-positive reactive microglia was observed in formalin-fixed paraffin-embedded brain sections from all 13 AIDS cases examined. Similar findings were observed in brain tissue from other neurological diseases (subacute sclerosing panencephalitis, herpes simplex encephalitis and multiple sclerosis). Multinucleated giant cells were found in 7 of the AIDS cases which were also intensely labeled for ferritin. Dual-label immunohistochemistry using anti-ferritin and cell-specific markers showed that ferritin-positive cells were distinct from astrocytes, neurons and endothelia using anti-glial fibrillary acidic protein (anti-GFAP), anti-neurofilament protein and Ulex europaeus agglutinin 1, respectively. In 5 AIDS brains, only ferritin-positive cells were shown to contain HIV-1 gp41 antigen using dual-label immunohistochemistry. In addition, HIV-1 RNA was localized in ferritin-positive reactive microglia but not in GFAP-positive astrocytes using immunohistochemistry combined with in situ hybridization. Ferritin-positive reactive microglia and multinucleated giant cells were co-labeled with the microglial marker, Ricinus communis agglutinin 1 (RCA-1). However, RCA-1 also extensively stained resting microglia only a few of which were co-labeled for ferritin. The density of ferritin-positive cells was correlated with the presence of HIV-1 RNA-positive cells in AIDS brain. Thus, ferritin immunoreactivity can be used as an activation marker of microglia in archival paraffin sections and reflects the extent of inflammation in HIV-1-infected brain.

The protection against gentamicin nephrotoxicity in the streptozotocin-induced diabetic rat is not related to gender

Since gender can influence the renal toxicity of a drug in a given species, the present study was undertaken to evaluate the role of sex in the protection against gentamicin (G)-induced nephrotoxicity afforded by diabetes mellitus (DM) in the rat. We have compared the effects of administration of G (40 mg/kg/day, for 14 days) on male and female DM Sprague-Dawley rats. Non-diabetic animals of both sexes receiving identical doses of G served as controls. At the end of the experiment on day 14, both female (F) and male (M) control groups had similar and marked evidence of nephrotoxicity: elevation of plasma creatinine (F 1.7 +/- 0.7; M 2.8 +/- 0.6 mg/dl), decrease in endogenous 24-h creatinine clearance (Ccr) (F0.3 +/- 0.1; M 0.2 +/- 0.1 ml/min/100 g BW), and histological evidence of severe acute tubular necrosis. In marked contrast, the DM rats showed no functional or morphological evidence of renal damage throughout the study regardless of their gender (day 14: plasma creatinine: F 0.2 +/- 0.03; M 0.2 +/- 0.02; Ccr: F 1.2 +/- 0.1; M 1.6 +/- 0.1 ml/min/100 g BW), and they also accumulated less G in their kidney cortex than the C rats. The male controls exhibited higher renal cortex accumulation of G than the female controls (p < 0.05), whereas the opposite occurred in the DM groups (p < 0.01). Because the validity of using Ccr for the evaluation of GFR changes in experimental nephrotoxicity has been questioned, we have compared, in a separate experiment, three different methods of estimation of GFR (simultaneous short clearances of inulin and Ccr, and 24-h Ccr) in conscious female Sprague-Dawley rats undergoing the same treatment with G described above. At no time during the study did the method used for estimation of the GFR influence the results. We conclude that male and female Sprague-Dawley rats with diabetes are functionally and morphologically equally protected against G. Furthermore, no gender-related differences in the magnitude of G-induced nephrotoxicity was demonstrated in the non-diabetic control animals.

The nephropathology in human immunodeficiency virus (HIV-1) infection

The nephropathology observed in patients with HIV infection is reviewed. A characteristic, though not specific, nephropathy associated with HIV infection can be encountered in HIV carriers, in patients with AIDS-related complex and in patients with AIDS. HIV-associated nephropathy typically exhibits the features of an aggressive form of focal and segmental glomerulosclerosis. Distinctive pathologic features include: 1) the "collapsing" and predominantly global pattern of glomerulosclerosis; 2) the severity of visceral epithelial cell hypertrophy and droplet formation; 3) the prominent tubular microcysts and cast formation; 4) the focal tubular degenerative features; and 5) the numerous tubuloreticular inclusions.

Renal biopsy in patients 65 years of age or older. An analysis of the results of 334 biopsies

We studied the clinical and pathological data for 334 patients age 65 or more who underwent renal biopsy for acute renal failure (ARF, n = 55), subacute renal failure (SRF, n = 72), chronic renal failure (CRF, n = 57), proteinuria (n = 137), and hematuria (n = 13). Tissue diagnoses were glomerulopathy (n = 252, 75.4%), acute tubular lesions (n = 18), interstitial nephritis (n = 23), vascular diseases (n = 36, including 14 with cholesterol emboli), and five miscellaneous diagnoses. Of the 55 patients with ARF, 23 had a glomerular lesion, 15 had acute tubular necrosis, and 8 had acute interstitial nephritis. Of 72 patients with SRF, 49 had a glomerulopathy, 12 had a vascular disorder, and six had acute interstitial nephritis. Hence, patients with ARF or SRF exhibited a high potential for reversible lesions. Only 11.3% of patients with CRF had potentially reversible causes. The most common causes of proteinuria were membranous glomerulopathy (34.3%), minimal change disease (14.6%), focal segmental sclerosis (11.7%), and amyloidosis (8.8%). Of the 25 patients with advanced nephrosclerosis, 24 had renal failure, 20 were hypertensive, and 13 had cholesterol emboli. Of 33 patients with diabetes mellitus, 66.7% were found to have lesions not related to diabetes. We conclude that renal biopsy is most useful in older patients with ARF or SRF because of potentially reversible renal disease. Old age alone is not a contraindication to performing a renal biopsy.

Urban helminthiasis in two socioeconomically distinct Costa Rican communities

A survey on the prevalence of Ascaris lumbricoides, Trichuris trichiura and Hymenolepis nana was conducted in two adjacent, but socioeconomically distinct, urban Costa Rican communities: a squatter settlement and a community with access to modern sewage facilities. The prevalence of these infections was significantly higher in the former. Although squatter children (1-14 years old) were more heavily infected with A. lumbricoides and H. nana than squatter adults, the same pattern was not observed for T. trichiura. The results suggest that local community-based helminthic parasite surveys may more accurately portray the actual health status of socioeconomically diverse urban populations.

Renal disease in children with the acquired immunodeficiency syndrome

Of 155 children with the acquired immunodeficiency syndrome (AIDS) whom we evaluated during a 6 1/2-year period, 12 were found to have proteinuria. Histologic studies of tissue from these 12 patients revealed a wide spectrum of renal disease: focal glomerulosclerosis in 5, mesangial hyperplasia in 5, segmental necrotizing glomerulonephritis in 1, and minimal change disease in 1. In addition, 6 had tubulointerstitial infiltrates, and 10 had glomerular dense deposits. All 10 renal specimens studied by electron microscopy contained endothelial tubuloreticular inclusions. The mean age (+/- SD) of the five patients with focal glomerulosclerosis when this condition was identified was 27 +/- 19 months. All five had severe renal failure within a year and died of other causes during the following year. The mean age of the five patients with mesangial hyperplasia was 38 +/- 31 months. Although none of them went on to have renal failure, four died within 8 +/- 7 months. Ten of the 12 patients with proteinuria died during the study period. Of the two surviving, one had mesangial hyperplasia and the other had minimal change disease. We conclude that children who acquire human immunodeficiency virus (HIV) infection during the perinatal period may have renal disease, most often focal glomerulosclerosis, as is the case in adults, or mesangial hyperplasia. Although 5 of the 12 children we studied had renal failure during the study period, none died of it. Further studies are needed to determine the correlations between clinical and pathological features and the pathophysiology of AIDS nephropathy in children.

Phlorizin-induced glycosuria does not prevent gentamicin nephrotoxicity in rats

Because rats with streptozotocin-induced diabetes mellitus (DM) have a high solute diuresis (glycosuria of 10 to 12 g/day), we have suggested that this may in part be responsible for their resistance to gentamicin-induced acute renal failure (ARF). The protection from gentamicin nephrotoxicity was studied in non-diabetic rats with chronic solute diuresis induced by blockage of tubular glucose reabsorption with phlorizin (P). DM rats with mild glycosuria (similar in degree to that of the P treated animals) were also studied. Unanesthetized adult female, Sprague-Dawley rats were divided in four groups and studied for 15 days. Group 1 (P alone) received P, 360 mg/day, for 15 days; Group II (P + gentamicin); Group III (gentamicin alone) and Group IV (mild DM + gentamicin). Nephrotoxic doses (40 mg/kg body wt/day) of gentamicin were injected during the last nine days of study to the animals of groups II to IV. In Group I, P induced a moderate and stable glycosuria (3.9 +/- 0.1 g/day, SE), and no functional or morphologic evidence of renal dysfunction (baseline CCr 2.1 +/- 0.1 ml/min, undetectable lysozymuria) or damage (tubular necrosis score [maximum 4], zero). In Group II, P did not prevent gentamicin-ARF (maximal decrease in CCr at day 9.89%, P less than 0.001; peak lysozymuria, 1863 +/- 321 micrograms/day; and tubular necrosis score, 3.9 +/- 0.1). These values were not different from those of Group III: maximal decrease in CCr 73% (P less than 0.001); lysozymuria, 2147 +/- 701 micrograms/day; tubular necrosis score, 3.8 +/- 0.1.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute and chronic renal effects of radiocontrast in diabetic rats. Role of anesthesia and risk factors

The acute and chronic renal effects of the intravenous injection of meglumine diatrizoate sodium 76% (CM), 5 mL/kg body weight were studied in diabetic (DM) and age-matched normal (C) female Sprague-Dawley rats. In acute studies, the effect of anesthesia was assessed for 2 hours. Although anesthesia decreased 14C-inulin clearance (Cin) in both DM and C rats (P less than .001 vs. conscious values), there was no impairment of Cin in either group after administration of CM. In chronic studies, creatinine clearance (Ccr) was followed for 3-4 days after CM administration. Four protocols to assess risk factors in DM and C were used: adult rats with normal hydration (2A); old dehydrated rats with DM of long duration (2B); rats with prior decreased Ccr (remnant kidney, 2C); and DM rats treated with insulin (2D). No clear-cut nephrotoxicity was apparent in these studies, except that proteinuria increased with CM in Study 2C. A greater severity of renal dysfunction, renal disease, or the association of multiple risk factors may be necessary to induce CM-related nephrotoxicity in the experimental animal. The rat, diabetic or not, may have an inherent resistance to CM-induced renal injury.

The clinical spectrum of renal disease associated with human immunodeficiency virus

A nephrology consultation was called on 100 adult patients of 1,635 (6.1%) patients with human immunodeficiency virus (HIV) infection seen between 1982 and 1987 at the University of Miami/Jackson Memorial Medical Center. Renal disease was observed in all groups of patients with a risk factor for HIV infection with a lesser incidence, however, among homosexuals. Intravenous drug (IVD) use and possibly race appear to be important factors in the development of renal complications. Renal disease was the dominant clinical feature in eight asymptomatic HIV carriers and in 34 patients with AIDS-related complex (ARC) who had not developed the opportunistic infections and/or malignancies associated with acquired immunodeficiency syndrome (AIDS). Ninety-one percent of consultations were requested for evaluation of proteinuria and/or renal failure. Nephrotic range proteinuria, in excess of 3 g/24 h, was present in 52 patients, and was less prevalent in homosexuals than in other groups at risk. Renal failure (serum creatinine greater than or equal to 5 mg/dL), initially present in 32 patients, eventually developed in 69 and improved in only 18 of them. A renal biopsy, obtained for work-up of nephrotic syndrome (22 patients) or renal insufficiency (3 patients), uncovered a picture of focal and segmental glomerulosclerosis in all 25 instances. Overall, 76 patients are dead, seven are lost to follow-up, and 17 are alive, of whom eight (four HIV carriers, two patients with ARC, and two with AIDS) are on maintenance hemodialysis with a mean survival time of 217 days.

In vivo and in vitro induction of class II molecules on canine renal cells and their effect on the mixed lymphocyte kidney cell culture

Canine renal cortical cells were obtained by collagenase extraction from allogeneic haploidentical, donor-recipient beagle littermate pairs and from unrelated mongrels. Peripheral blood lymphocytes (PBL) of the mongrels, as well as of one member of the beagle pair that exhibited high mixed lymphocyte culture (MLC) reactivity against the other were also stimulated by renal cortical cells derived from both normal and rejected transplanted kidneys in mixed lymphocyte kidney cell culture (MLKC). A moderate autologous MLKC reactivity occurred in response to normal renal cortical cells. However, rejected kidney cortical cells were markedly more stimulatory than normal renal cortical cells in both allogeneic and autologous MLKC reactions. Lymphocytes from donor animals responded more strongly to autologous cortical cells isolated during rejection of the transplant than to cortical cells from normal allogeneic kidneys. Recipient infiltrating lymphocytes and propagated T cell lines extracted from the rejected kidney also responded more strongly than PBL to cortical cells from this kidney. Gradient purification of the stimulating cortical cells resulted in one virtually pure preparation of distal tubular epithelial cells, as demonstrated by immunohistochemical stains and electron microscopy, which caused enhanced stimulation in MLKC. Class II marker analysis of the canine renal cells from rejected kidneys revealed the presence of these molecules on tubular cells that were absent on normal kidney cells. A 16-hr coculture of normal renal cortical cells not exhibiting class II surface markers in the presence of allogeneic or autologous lymphocytes induced the expression of these molecules, associated with an increased stimulatory capacity. This also occurred to a lesser extent with MLC (and MLKC) cell culture media supernatants. However, the low level of class II expression by all the various gradient-purified fractions in the absence of rejection or coculture, and the increased but equivalent expression on all fractions after coculture did not correlate with the preferential stimulatory capacity of the purified distal tubular cell layer. We conclude that two signals are necessary for the MLKC reaction, one involving tissue (kidney)-associated epitopes (the nominal antigen demonstrated in this study to be present in normal distal tubular cells), the other involving class II molecules as costimulatory (amplification) moieties.

Renal involvement in essential mixed cryoglobulinemia

Essential mixed cryoglobulinemia (EMC) is infrequently recognized in this country. We report studies performed in six patients with EMC evaluated by us over the last 6 years. Purpura was present in three patients and glomerulonephritis in all. Two patients had chronic hepatitis B infection. Positive cryoglobulins and C1q binding, hypocomplementemia (especially low C4), positive rheumatoid factor titer, and negative anti-DNA antibodies were characteristic laboratory findings. The cryoprecipitate had strongly positive rheumatoid factor activity and contained a monoclonal IgM, kappa type in one of the two patients evaluated. The predominant lesion by renal biopsy was mesangiocapillary glomerulonephritis type I; electron microscopy revealed typical fibrillar structures in four cases. The above-mentioned features help distinguish EMC from other forms of glomerulonephritis.

AIDS-related glomerulopathy: occurrence in specific risk groups

The histopathology and incidence of AIDS-related glomerulopathy was evaluated by renal biopsy (N = 24) or at autopsy in 159 patients, including 131 adults and 28 infants and children with AIDS. Thirty-five patients had overt clinical manifestations of renal disease characterized by a nephrotic syndrome with focal and segmental glomerular sclerosis (FSS). Fifteen patients had diffuse glomerular mesangial hyperplasia (MH) without or with minimal clinical renal disease and 109 had intact or minimally involved glomeruli. Whereas 15 of 30 (50%) i.v. drug users with AIDS had evidence of renal disease, only one of 53 (2%) homosexuals had clinical renal disease and only 6 (11%) had histologic evidence of glomerular pathology. The study confirms the important risk of i.v. drug use as a pathogenic factor of renal disease and shows a rarity of renal disease in homosexual or bisexual men with AIDS. On the other hand, 30% of adult Haitians with AIDS had FSS or diffuse MH, although i.v. drug use is not an important risk factor in this population. Moreover, eight of 28 (29%) children with perinatal AIDS had evidence of renal involvement, including four with a nephrotic syndrome and FSS. The data provide strong evidence for the existence of an AIDS-related glomerulopathy independent of i.v. drug use, but suggest that unrecognized co-factors may be important in the development of renal disease.

Glomerular function and morphology after renal mass reduction in dogs

To determine whether the proteinuria, glomerular sclerosis, and decline in glomerular filtration rate (GFR) described in rodents after renal mass reduction develop in another species, 24-hour proteinuria, glomerular structure, and fasting and postfeeding GFR were examined in dogs subjected to seven-eighths reduction in renal mass. All dogs were fed a diet containing 26% protein. Six dogs with a GFR less than 10 ml/min (8% to 17% of control two-kidney GFR) were killed within 6 months after renal mass reduction. Twenty-four-hour urinary protein excretion was modestly although definitely increased (236 +/- 26 mg/24 hr, P less than 0.01). All remnant kidneys demonstrated structural changes of mesangial hyperplasia or focal glomerular sclerosis. Ten dogs with a remnant kidney and early GFRs 16% to 39% of control values were followed for 18 to 39 months. In seven dogs, GFR showed little tendency to decrease with time. In one of them, proteinuria was 106 mg/24 hr with normal-appearing glomeruli at 14 months. In three dogs, proteinuria was progressive, averaging about 1 gm/24 hr at 18 months and 2 gm/24 hr at 24 to 34 months; glomerular pathologic findings progressed from focal mesangial hyperplasia or focal glomerular sclerosis at 8 to 16 months to focal and segmental sclerosis or diffuse glomerular obsolescence at 25 to 34 months; and fasting GFR progressively declined starting at 21 to 24 months after renal mass reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

T cell lines and clones preferentially recognizing kidney-associated antigens in end-stage renal disease

The specificity in the mixed lymphocyte kidney culture (MLKC) of T cell lines and clones derived from human end-stage renal disease (ESRD) kidneys was studied using collagenase dispersed kidney cells compared with lymphocytes as stimulating cells. These experiments were performed because of previous studies in which infiltrating lymphocytes freshly isolated from ESRD kidney tissue at nephrectomy (as well as autologous splenic T cells) were seen to directly generate this lymphoproliferative MLKC response when stimulated with autologous renal cortical cells. In the current studies, histopathologic staining of tissues and suspensions of infiltrating kidney lymphocytes showed predominance of OKT4 labeled phenotypes, and the stimulation indices in MLKC in general showed a direct relationship with the percentage of helper cells seen in the infiltrates. When T cell lines and clones derived from lymphocytes infiltrating the ESRD kidneys were tested in MLKC, there was evidence of kidney-associated, as opposed to lymphocyte-associated (MLC) reactivity using (3H) thymidine uptake as a reflection of a lymphoproliferative response. Several cell lines and clones derived from these T lymphocytes exhibited a dual reactivity. They served as responding cells in the MLKC reaction and completely suppressed a non-specific allogeneic MLC when added as third-party cells. Quantitatively, some clones suppressed when third-party x-irradiated cells were only 5% of the responding cell number in coculture. In addition to the dual reactivity, phenotypic analysis of these same cell lines and clones employing monoclonal antibodies revealed that individual cells expressed both OKT4 and OKT8 determinants. However, approximately 90% of the cells in the MLC enhancing line were labeled with OKT4. These results indicate that there is a complexity in the autologous MLKC response in that cells with both helper/inducer and suppressor/cytotoxic function take part in the reaction. Although delayed-type hypersensitivity to kidney-associated antigens is inferred as a result of these in vitro assays, nonspecific suppression of other Ia-dependent reactions can simultaneously occur.

The biologic significance of the mixed lymphocyte kidney culture in humans

The mixed lymphocyte kidney culture (MLKC) in humans has been studied in normal and abnormal clinical conditions. Human renal cortical cells were extracted by collagenase treatment from the kidneys of "normal" heart-beating cadaver organ donors (n = 13), patients with end-stage renal disease (ESRD) at pretransplant bilateral nephrectomy and splenectomy (n = 13), and from irreversibly rejected renal allografts at the time of graft nephrectomy (n = 5). Proliferation of peripheral blood T lymphocytes of 2-DR-mismatched volunteers occurred in response to kidney cortical cells extracted from each of the 3 donor categories in a reaction termed the allogeneic mixed lymphocyte kidney culture. Additionally, splenic T cells from cadavers and patients with ESRD were seen to react to their autologous kidney cells. The renal cortical cells extracted from ESRD kidneys were more stimulatory in the allogeneic and autologous MLKC responses than those extracted from "normal" cadaver kidneys even when the ESRD kidneys were 99% depleted of passenger T and B lymphocytes by treatment with monoclonal antibodies T11 and B1. In order to help define the antigens operative in the MLKC, we pretreated stimulating lymphocytes and renal cortical cells with anti-class II monoclonal antibodies. The allogeneic mixed lymphocyte reaction and MLKC were inhibited ca. 80% and 30%, respectively. The autologous MLKC was unaffected by this treatment. To further support that tissue-specific immune mechanisms were operative in the reaction, experiments were performed with infiltrating lymphocytes isolated from the ESRD kidneys, which were seen to generate a proliferative response when stimulated with autologous cortical cells. However, the response of these same infiltrating lymphocytes when stimulated with allogeneic lymphocytes (MLR), was markedly weaker than the response of the patients' autologous spleen cells. In addition, two kidneys were obtained at rejection from recipients that had received grafts from HLA-MLR-identical sibling donors. A lymphoproliferative reaction of recipient peripheral blood T lymphocytes occurred in response to (donor) renal cortical cells, but not to donor peripheral blood lymphocytes. In contrast, infiltrating (recipient) kidney lymphocytes responded to the kidney cortical cells and to donor peripheral blood lymphocytes. Moreover, peripheral blood T lymphocytes of the HLA-identical donor responded to his own kidney cortical cells, which were isolated from the rejected recipient kidney, and did not respond to recipient peripheral blood lymphocytes. Finally, a "normal" cadaveric kidney was fortuitously available at the same time that a rejected transplant (cadaver)

Glomerular lesions in the acquired immunodeficiency syndrome

Between January 1982 and December 1983, 75 patients with the acquired immunodeficiency syndrome were identified in our hospitals: 35% used intravenous drugs, 50% had proteinuria in excess of 0.5 g/dL, and 10% were nephrotic. Glomerular changes seen at autopsy in 36 patients included frequent mesangial lesions and deposits associated with mild asymptomatic proteinuria. Focal and segmental glomerular sclerosis was found in 5 patients and 4 of these had the nephrotic syndrome. Whereas reversible episodes of acute renal failure were not uncommon, terminal episodes of acute renal insufficiency occurred in 14 patients. The short survival of these patients may prevent the development of chronic renal failure.

The clinical significance of mesangial IgM deposits and mesangial hypercellularity in minimal change nephrotic syndrome

Some patients with minimal change nephrotic syndrome (MCNS) present on biopsy mesangial IgM deposits, which may be associated with mesangial hyperplasia. These patients have been considered as a possible subset with a different response to therapy as well as prognosis and designated as mesangial IgM nephropathy or mesangial proliferative glomerulonephritis. However, the clinical relevance of these biopsy findings has been questioned by others. We reviewed the clinical, biopsy, and follow-up data in 61 MCNS children, 33 with mesangial IgM and 28 free of immunoglobulins. There were no significant differences in response to therapy or prognosis between these two groups. The lack of IgM elution and heterologous in vitro C3 fixation in the biopsies of some MCNS cases with IgM mesangial deposits does not support the possibility that the deposited IgM plays an immunologic role.

Glomerular disease in two patients with urticaria-cutaneous vasculitis and hypocomplementemia

We assessed the clinical, serologic, and renal abnormalities of two patients with the syndrome of hypocomplementemia, vasculitis, and urticaria. Both patients presented with recurrent urticaria and were found subsequently to have glomerulonephritis. Both manifested depletion of the early complement (C) components, and their Cl inhibitor levels were normal. Circulating immune complexes were detected by two of three assays in both patients. One patient had a high titer of Sm antibodies. The detectable immune complexes were of high molecular weight, and were more suggestive of classical lupus erythematosus than the low molecular weight (7S) Clq precipitins which characterize some cases of hypocomplementemia-vasculitis-urticaria syndrome. Biopsy of the skin lesions in both patients revealed leukocytoclastic vasculitis with immunoglobulin and C deposits at the dermal-epidermal junction. Renal biopsy specimens showed segmental or diffuse proliferative mesangial glomerulonephritis. The results suggest that patients with this syndrome do not conform to a discrete entity but rather exhibit a spectrum of diseases ranging from systemic lupus erythematosus to the syndrome of urticaria, hypocomplementemia, and low molecular weight Clq precipitins.

Delayed form of Wegener's granulomatosis

We have described a patient in whom renal manifestations preceded the pulmonary findings of Wegener's granulomatosis by two years. He presented with rapidly progressive glomerulonephritis requiring chronic hemodialysis despite treatment with prednisone and azathioprine. Wegener's granulomatosis was diagnosed only after other signs of the generalized form of the disease had become manifest. Review of the literature revealed four similar cases. In patients with similar clinical presentations, serious consideration should be given to this delayed form of the syndrome. A course of cytotoxic therapy should be tried while the patient is followed up for further manifestations of generalized Wegener's granulomatosis.