Effective therapy for severe Henoch-Schonlein purpura nephritis with prednisone and azathioprine: a clinical and histopathologic study

OBJECTIVES

To validate a scoring system to assess the severity of renal lesions and to correlate histology with clinical findings. We also examined the efficacy of treatment with prednisone (1 to 2 mg/kg/d) and azathioprine (1 to 2 mg/kg/d) for severe Henoch-Schonlein purpura (HSP) nephritis.

METHODS

Twenty patients were evaluated retrospectively. All underwent biopsy before treatment, and 13 underwent biopsy after therapy. We developed a scale based on glomerular, tubulointerstitial (TI), and vascular changes and assigned all specimens acuity, chronicity, and TI scores. The outcomes of 17 patients were compared with those of a historical control group.

RESULTS

Chronicity score at initial biopsy increased with increasing delay between onset of renal involvement and first biopsy (rho = 0.55, P =.016) but did not progress after treatment was initiated. Both acuity (rho = 0.57,P =. 016) and TI (rho = 0.69, P =.003) scores correlated with clinical severity at first biopsy. The TI score correlated negatively with serum albumin (rho = -.60, P <.01). Significantly more patients in the study group than in the control group had a favorable outcome (15 [88%] of 17 vs 32 [54%] of 59, P =.011).

CONCLUSIONS

Our scale reflects disease activity and highlights the importance of TI changes in severe HSP nephritis. Outcome comparisons indicate that early treatment with prednisone and azathioprine prevents progression of chronic changes and improves outcome.

Site-specific epithelial-mesenchymal interactions in digestive neuroendocrine tumors. An experimental in vivo and in vitro study

Little is known about the functional interactions between digestive neuroendocrine tumor cells and their stromal microenvironment. The focus of our study is whether mesenchymal cells modulate peptide expression, cell proliferation, and invasiveness in digestive neuroendocrine tumor cells. We designed an experimental in vivo and in vitro study using the mouse enteroendocrine cell line STC-1. In vivo, STC-1 cells were injected subcutaneously in 18 immunosuppressed newborn rats. At day 21, all animals presented poorly differentiated neuroendocrine tumors with lung metastases. Subcutaneous tumors were usually limited by a capsule containing basement membrane components and myofibroblasts that presented a low mitotic index. Lung tumors were devoid of capsule and poor in myofibroblasts, and their mitotic index was high. The profile of peptide expression in STC-1 tumors was different from that of cultured STC-1 cells. In vitro, STC-1 cells were cultured with fibroblasts of different origins, including dermis, lung, digestive tract, and liver. Based on their origin, myofibroblasts differentially modulated hormone synthesis, proliferation, spreading, and adhesion of STC-1 cells. In conclusion, our results show that site-specific functional interactions between mesenchymal and neuroendocrine cells may contribute to modulating the behavior of digestive neuroendocrine tumors, depending on their growth site.

Oncostatin M induces interleukin-6 and cyclooxygenase-2 expression in human vascular smooth muscle cells : synergy with interleukin-1beta

Oncostatin M (OSM), a cytokine first identified from activated monocytes and T lymphocytes, is one of the most potent autocrine growth factor for AIDS and Kaposi's sarcoma. Little is known about the effects of OSM on normal vascular cells. We thus exposed human aortic smooth muscle cells (hASMCs) to OSM, examined cell proliferation and morphology, and determined interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) expression. OSM had a weak antiproliferative effect. After a 4-day incubation with 100 ng/mL OSM, cell count decreased to 69+/-3% of control. However, OSM induced striking changes in hASMC morphology, characterized by a polyclonal shape, in contrast to the spindle morphological feature of control hASMCs. OSM stimulated the release of IL-6 by hASMCs in a dose-dependent way; after a 48-hour exposure, values were 8.5+/-0.7, 29.7+/-3.5, 50.9+/-4.4, and 73.8+/-7.6x10(3) U/mL (n=6) at OSM concentrations of 0, 1, 10, and 100 ng/mL, respectively. OSM induced marked expression of COX-2 protein and mRNA. Leukemia inhibitory factor had no effect on hASMCs, indicating that OSM effects on hASMCs were mediated by the OSM type II receptor and not by the leukemia inhibitory factor receptor. OSM used the JAK/STAT signaling pathway, as demonstrated by rapid phosphorylation of JAK1 and specific activation of STAT1. Interestingly, OSM acted in synergy with IL-1beta on IL-6 production and COX-2 expression. In conclusion, OSM is a novel regulator of human smooth muscle cell functions, acting in concert with IL-1beta, and OSM may play a role in major vascular diseases such as atherosclerosis.

Development of intracellular calcium measurement by time-resolved photon-counting fluorescence

Calcium green I, a ratiometric probe based on fluorescence lifetime measurements, was used to monitor intracellular calcium activity ([Ca2+]i) in RINm5F cells using a time-resolved fluorescence confocal microscope. The probe affinity constant has been recalibrated in single cells using ionomycin as a calcium ionophore and ethylenebis(oxyethylenenitrilo)tetraacetic acid as a calcium buffer; Kd was found to equal 150 nmol/L. The kinetics of ionomycin equilibration showed that the calcium release from calcium stores occurs before equilibration with extracellular calcium. The response to the muscarinic agonist carbachol, measured on 17 cells receiving three consecutive applications was characterized both by a [Ca2+]i peak lasting 50 s without any trailing plateau and by desensitization with a 30% decrease in the response. The dose-dependent response was obtained for a carbachol concentration from 5 mumol/L to 0.5 mmol/L. The ability of our set-up to obtain a value every 10 ms enabled us to record asynchronous spikes of [Ca2+]i in the RINm5F cells. The spikes, lasting less than 1 s, are significantly bigger than the noise, and they are not observed in the colonic HT29 cells.

A new mechanism conferring unprecedented high resistance to chlorpyrifos in Culex pipiens (Diptera: Culicidae)

The cause of high resistance to chlorpyrifos observed in Tunisian Culex pipiens (L.) was investigated by comparing a Tunisian strain G (> 10,000-fold resistance), a French strain T (approximately 50-fold resistance), and a susceptible reference strain S. Strains G and T had the same level of propoxur resistance (approximately 1,000-fold) and were homozygous for an autosomal propoux-insensitive acetylcholinesterase (AChE-1). In G and T strains, as well as in the offspring of different F1s and backcrosses using these F1s and the S strain, the effect of DEF and Pb synergists on chlorpyrifos resistance was low or absent, indicating that increased detoxification by enzymes inhibited by these chemicals had a minor role. Chlorpyrifos resistance in the G strain was caused by a major gene (or group of genes) tightly linked to the Ace-1 gene (coding AChE-1 enzyme). The possibility of allelism between this gene and the Ace-1R allele present in the T strain was rejected by showing that AChE-1 inhibition by chlorpyrifos-oxon was not different between G and T mosquitoes.

Human normal dermal fibroblasts express somatostatin receptors

The hormone/neuropeptide somatostatin (SOM) exerts multiple functions in the central nervous system, the immune system, the hypothalamo-pituitary axis, the gastrointestinal tract, and the pancreas. Endogenous SOM occurs in 2 biologically active forms, with 14 or 28 amino acids. Five subtypes of SOM receptors have been cloned. SOM is present in human skin. We have investigated the expression of SOM receptors on human dermal normal fibroblasts. Biotinyl-SOM allowed the visualization of SOM receptors on human dermal fibroblasts. Radioligand binding studies with (3-[125I]iodotyrosyl11)-SOM-14 were performed on these cells and the effect of SOM-14 on the DNA synthesis by fibroblasts was evaluated by measuring [3H]-methyl thymidine incorporation. Saturation curve, and Scatchard plot showed a homogeneous class of receptors with a Bmax of 0.055 +/- 0.023 nM and KD of 2.0 +/- 0.4 nM (values: mean +/- SEM). Fibroblasts expressed 3,317 +/- 1,385 binding sites per cell. Competitive displacement experiments showed that SOM-14 IC50 was 69.3 +/- 4.5 nM (mean +/- SEM), for SOM-28 33.2 +/- 6.0 nM and for octreotide 36.5 +/- 3.3 nM. The KI values calculated from these IC50 were, respectively: 62.4 +/- 4.1 nM; 29.9 +/- 5.4 nM; 32.9 +/- 2.9 nM. We conclude that subtype 2 or 3 SOM receptors is present on human normal dermal fibroblasts. A weak effect of SOM-14 on DNA synthesis was observed with SOM concentrations of 10(-7) and 10(-6) M.

Neogenesis vs. apoptosis As main components of pancreatic beta cell ass changes in glucose-infused normal and mildly diabetic adult rats

We have investigated in adult rats made mildly diabetic by a low dose of streptozotocin (35 mg/kg; STZ rats) and in nondiabetic rats (ND rats) the mechanisms leading to adaptive changes in the beta cell mass, during glucose infusion and several days after stopping infusion. As early as 24 h of glucose infusion, the beta cell mass was maximally increased in ND and STZ rats. In both groups, this increase was due mainly to a rapid activation of neogenesis of new endocrine cells rather than to an increase in beta cell proliferation. Seven days after stopping glucose infusion, the beta cell mass returned to basal values in both groups as a result of stimulation of beta cell apoptosis and a decrease in beta cell replication rate. In glucose-infused ND rats, changes in the beta cell mass were correlated to insulin secretion, whereas in STZ rats, insulin secretion in response to glucose was still impaired whatever the beta cell mass. In conclusion, the data stress the impressive plasticity of the endocrine pancreas of adult rats. They also show that changes in beta cell mass in ND and STZ rats resulted from a disruption in the balance between neogenesis and apoptosis.

Quantitative variation and selection of esterase gene amplification in Culex pipiens

Although descriptions of evolutionary mechanisms are common in the literature, very few studies focus on the possible evolution of the adaptive genes themselves, i.e. their quantitative and qualitative changes. Evolution of insecticide resistance in Culex pipiens is a suitable model for studying such processes. In this species, organophosphorous insecticide resistance can be achieved through the overproduction of esterases that sequester the insecticide, and this overproduction can be caused by gene amplification. It is generally assumed, but never verified, that esterase activity, and therefore resistance, is monotonically related to gene amplification. We have analysed resistance, esterase activity and gene amplification in different laboratory strains and natural populations in order to detect variability and to infer effects of selection on these factors. We have shown that resistance, esterase activity and amplification covary, that insecticide selection is able to increase amplification levels, and that a fitness cost is probably attached to the amplification in laboratory strains, related to the level of amplification. The importance of variation in gene amplification level is discussed and some evolutionary implications are proposed.

[The Vosges-Meuse mobile MRI unit]

The authors describe the advantages and the pitfalls of the first mobile MR unit in metropolitan France. For the last year, this unit has been providing services to five hospitals and a private clinic. The greatest distance between 2 hospitals was 230 km (144 miles).

Newly formed excitatory pathways provide a substrate for hyperexcitability in experimental temporal lobe epilepsy

Temporal lobe epilepsy (TLE) in humans and animals is associated with axonal sprouting of glutamatergic neurons and neosynaptogenesis in the hippocampal formation. We examined whether this plasticity of excitatory pathways contributes to an increased level of glutamatergic excitation in the CA1 region of rats experiencing chronic spontaneous limbic seizures following kainic acid or pilocarpine treatment. In chronic cases, we report an extensive axonal sprouting of CA1 pyramidal neurons, with many axonal branches entering the pyramidal cell layer and stratum radiatum, regions that are not innervated by axonal collaterals of CA1 pyramidal neurons in control animals. Concurrently with this anatomical reorganization, a large increase of the spontaneous glutamatergic drive is observed in the dendrites and somata of CA1 pyramidal cells. Furthermore, electrical activation of the reorganized CA1 associational pathway evokes epileptiform bursts in CA1 pyramidal cells. These findings suggest that reactive plasticity could contribute to the hyperexcitability of CA1 pyramidal neurons and to the propagation of seizures in these two models of TLE.

Effect of mild hypothermia on the vascular actions of phenylephrine in rat aortic rings

Intraoperative mild hypothermia is common. We have investigated the effects of mild hypothermia (34 vs 38 degrees C) on phenylephrine--(10(-8) to 10(-5) mol litre-1) induced contractions of rat aortic rings mounted for isometric tension recordings. A marked decrease in Emax (maximal tension) (P < 0.05) and significant increase in EC50 (phenylephrine concentration producing 50% of maximal tension) were observed at the lower temperature in endothelium intact rings, but there was no effect of temperature when the endothelium had been removed. The decreased contraction with hypothermia in the endothelium intact vessels was restored to 84% by administration of the nitric oxide synthase inhibitor L-NNA and a small additional amount of tone was restored in the presence of the cyclooxygenase inhibitor, indomethacin. We conclude that mild hypothermia markedly decreased phenylephrine-induced rat aortic contraction in vitro by endothelium dependent mechanisms, largely related to increased nitric oxide production or action.

Exogenous CCK and gastrin stimulate pancreatic exocrine secretion via CCK-A but also via CCK-B/gastrin receptors in the calf

A predominance of the pancreatic cholecystokinin (CCK) receptor of the B/gastrin subtype (CCK-B/G) was reported in calves older than 1 month. Specific CCK-A and CCK-B/G receptor antagonists (SR 27897 and PD 135158, respectively) were used to identify the CCK receptor subtype involved in exogenous CCK- and gastrin-induced exocrine pancreatic responses. Conscious calves (2 months old) with catheterized pancreas, jugular vein and duodenum were used; the pancreatic juice was continuously reinfused. CCK (30 pmol kg-1 min-1, 40 min) evoked an increase in pancreatic juice flow and enzyme secretion, while the same dose of gastrin increased enzyme secretion alone. CCK-induced pancreatic secretion was abolished by SR 27897 (15 nmol kg-1 min-1, 55 min) and reduced by PD 135158 (0.15 nmol kg-1 min-1, 55 min). Gastrin-induced enzyme secretion was reduced by PD 135158 (50% to 90%) and to a lesser extent by SR 27897 (50% to 60%). These results demonstrate that CCK and gastrin in the physiological range stimulate pancreatic exocrine secretion in calves and that these effects are partly mediated by CCK-B/G receptors. Although CCK-A receptors are not predominantly expressed, they seem to play a major role in the response of pancreatic exocrine secretion to CCK.

Characterization of a variable number tandem repeat region in the thiopurine S-methyltransferase gene promoter

Characterization of the genetic polymorphism of thiopurine S-methyltransferase enzyme (TPMT; EC 2.1.1.67) is required because of its clinical importance for patients exposed to thiopurine drugs. A number of point mutations have already been characterized in exons and introns of the TPMT gene. Here we report the identification of a polymorphic locus within the promoter region of the gene. This polymorphism was detected by polymerase chain reaction - single strand conformation polymorphism analysis of DNA samples from 54 unrelated European individuals. A total of five alleles with length variations were distinguished through the 5'-flanking region involved in the TPMT gene expression. Sequence analysis revealed that these variations were due to a variable number of tandem repeats (VNTR), ranging from four to eight repeats. Each repeat consists of 17 or 18 bp units and contains putative binding sites for transcription factors. The most frequent alleles harbour four or five tandem repeats, a heterozygosity rate of 0.44 was calculated, and a stable Mendelian inheritance of alleles was demonstrated. Analysis of the effect of each VNTR allele on promoter activity of a reporter gene was further performed in various cell lines by transient transfection assay. A modulatory effect of VNTR alleles was observed in vitro, but the repeat polymorphism did not display a significative role in TPMT gene regulation in vivo. Further studies need to be carried out to support the hypothesis that VNTR may contribute to the large interindividual variations of TPMT activity.

Gut regulatory peptide levels in bovine fetuses and their dams between the 3rd and 9th months of gestation

Several gut regulatory peptides were measured by radioimmunoassay between 3 and 9 months of gestation in the plasma of 91 bovine fetuses and their dams, in fetal gastric content and in amniotic fluid. During gestation, plasma peptide concentrations did not change in cows. Likewise, fetal plasma concentrations of cholecystokinin, somatostatin, secretin and vasoactive intestinal polypeptide showed no variation while those of gastrin, pancreatic polypeptide and gastric inhibitory polypeptide increased during the last 6 months. Peptide levels in the fetus were higher than or equal to maternal concentrations. At 8-9 months of gestation, gastrin, CCK, secretin and somatostatin concentrations in amniotic fluid were lower than those measured in fetal gastric content and in maternal and fetal plasma. Therefore, a substantial endogenous endocrine production of regulatory peptides by the fetus probably exists as early as the third month of gestation, accompanied by a release into the lumen of the gut.

Epidermal growth factor receptor and labeling index are independent prognostic factors in glial tumor outcome

The aim of this study was to perform a multivariate analysis including clinical and biological prognostic factors on glial tumor outcome. Seventy-nine patients were analyzed (48 men and 31 women; mean age = 56 years, range = 16-77 years): 7 had a benign glial tumor (grades 1 and 2), 21 had an anaplastic glial tumor (grade 3), and 51 had a glioblastoma (grade 4). Median follow-up was 17.9 months for patients who survived (50 patients died). Biopsies were obtained at time of diagnosis (complete tumor resection in 62 patients and stereotaxic biopsies in 17 patients). Epidermal growth factor receptor (EGFR) was measured by a binding assay, and labeling index (LI) was measured by tritiated thymidine incorporation. EGFR varied from 4 to 73,110 fmol/mg protein (mean = 3912 fmol/mg protein; median = 374 fmol/mg protein; n = 79). LI varied between 0.1 and 16.5% (mean = 6.2%; median = 5.2%; n = 40). Log10 EGFR was significantly and positively correlated with patient age. LI was significantly different according to tumor histology. Univariate Cox analysis (end point was cancer death) showed that age (P = 0.027), log10 EGFR (P = 0.025), and LI (P = 0.0019) were significant continuous variables, the survival being shortened when the covariable increased; tumor resection (P = 0.015, relative risk = 0.45) and histology (P = 0.0009) were significant categorical factors. A multivariate Cox analysis (forward selection) including age, histology, tumor resection, log10 EGFR, and LI revealed that log10 EGFR, LI, and tumor resection were the only independent significant predictors of survival. This multivariate approach reveals that the clinical prognostic factors of glial tumors, namely age and tumor histology, disappear, to the benefit of intrinsic characteristics of the tumor, i.e., EGFR expression and LI, suggesting that coupled EGFR and LI determination could be a useful tool for better evaluation of glial tumor outcome.

GluR5 kainate receptor activation in interneurons increases tonic inhibition of pyramidal cells

We studied the modulation of GABAergic inhibition by glutamate and kainate acting on GluR5-containing kainate receptors in the CA1 hippocampal region. Glutamate, kainate or ATPA, a selective agonist of GluR5-containing receptors, generates an inward current in inhibitory interneurons and cause repetitive action potential firing. This results in a massive increase of tonic GABAergic inhibition in the somata and apical dendrites of pyramidal neurons. These effects are prevented by the GluR5 antagonist LY 293558. Electrical stimulation of excitatory afferents generates kainate receptor-mediated excitatory postsynaptic currents (EPSCs) and action potentials in identified interneurons that project to the dendrites and somata of pyramidal neurons. Therefore glutamate acting on kainate receptors containing the GluR5 subunit may provide a protective mechanism against hyperexcitability.

Clinical features of X-linked nephrolithiasis in childhood

X-linked recessive nephrolithiasis (XRN) is a rare hereditary form of progressive renal failure characterized by (1) proximal tubular dysfunction and low molecular weight proteinuria; (2) hypercalciuria with nephrocalcinosis and nephrolithiasis. Because the clinical features are non-specific and variable, affected families in different parts of the world were initially thought to have several distinct syndromes. However, positional cloning of the relevant gene (CLCN5) demonstrated that these families have, in common, mutations affecting a chloride channel expressed throughout the renal tubule. To expand the description of early clinical and pathological manifestations of XRN, we describe three patients diagnosed in the 1st decade of life. Renal tubular dysfunction may be evident even in the neonatal period, hypophosphatemic rickets may develop in the first years of life, and nephrocalcinosis (but not nephrolithiasis) with glomerulosclerosis are consistent features in childhood. One of our patients is indistinguishable from the others on clinical grounds, yet no mutations of the coding regions of the CLCN5 gene were found, raising the possibility of genetic heterogeneity in the XRN syndrome.

Reversal of excitatory postsynaptic potential/spike potentiation in the CA1 area of the rat hippocampus

In the CA1 area of the hippocampus, low frequency and tetanic conditioning stimuli are known to trigger long-term depression and potentiation of synaptic responses respectively and to produce irreversible excitatory postsynaptic potential/spike potentiation, i.e. an increase of the probability of discharge of the neurons. Using simultaneous extracellular recordings in stratum radiatum and stratum pyramidale in the CA1 area of the rat hippocampus, brief application of the K+ channel blocker tetraethylammonium resulted both in long-term potentiation of synaptic responses and in excitatory postsynaptic potential/spike potentiation that could be reversed by subsequent low frequency or tetanic stimuli. Excitatory postsynaptic potential/spike potentiation and its subsequent reversal by an electrical conditioning stimulus were found to have an N-methyl-D-aspartate receptor-independent component. We conclude that the reversal of excitatory postsynaptic potential/spike potentiation can occur and that it does not require the induction of long-term modification of synaptic responses.