P13.22 Menglia: an innovative approach to liquid biopsies in glioma patients

BACKGROUND

Gliomas are the second most frequent primary brain tumor. Since 2016 gliomas are classified according to histological, and molecular features such as IDH status and 1p19q codeletion. Recently oncological research has focused on liquid biopsies to reduce the need for invasive diagnostic tests. Cerebrospinal fluid (CSF) is the principal source of brain tumor biomarkers. Modern technologies currently allow us to analyze proteomic and metabolomic tumor profiles, in order to find new biomarkers without being constrained by a priori hypothesis. Several data from the literature also suggests that inflammatory cells and cytokines in tumors contribute to tumor growth, progression and immunosuppression. The possibility of simultaneously testing different inflammatory molecules on the biological fluids could lead to the identification of new biological markers with prognostic and predictive value for treatment response.

STUDY OBJECTIVES

- Identification of protein and/or lipid biomarkers specific to the glioma subgroup among those under analysis. - Identification of tumor group- and subgroup-specific CSF and/or serum inflammatory biomarkers among those tested. - Correlation of biomarkers with Progression Free Survival (PFS), Overall Survival (OS).

ELIGIBILITY CRITERIA

- Patients with a radiological suspected diagnosis of glioma eligible for surgery. - Age ≥ 18 years. - Availability of histological samples, CSF, blood and urine. - Patients with unconfirmed histological diagnosis of glioma will be excluded. - Patients who have never received any systemic or local treatment for CNS diseases.

STUDY DESIGN

This is a prospective monocentric study involving mass spectrometry analysis for characterization of proteins and metabolites and ELISA analysis for the characterization of different cytokines in parallel anonymized biological samples consisting of tumor tissue, CSF, blood and urine from glioma patients, divided into three different molecular subtypes: 1p19q codelet/IDH mutated, 1p19q non-codelet/IDH mutated and 1p19q non-codelet/IDH wt. Biological samples will be taken at surgery, at 24–48 h after surgery and every 3 months up to 1 year. The control group will include patients with subarachnoid hemorrhage or hydrocephalus, either undergoing external ventricular shunting or undergoing ventricular catheter placement/revision surgery.

STUDY ANALYSIS

Data interpretation will be based on a statistical analysis of the data, applying tools such as Principal Component Analysis (PCA) Weighted Correlation Network Analysis (WGNCA), Multiple Venn Diagram, T-Test, ANOVA, Clustering and Gene Ontology Enrichment, non-parametric Mann-Whitney test. For the assessment of clinical outcome, survival curves will be compared between different groups of patients who share a similar protein/metabolomic/inflammatory profile.

Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy

When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned.Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u(-1) (12)C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

Glomerular clusterin is associated with PKC-alpha/beta regulation and good outcome of membranous glomerulonephritis in humans

Mechanisms for human membranous glomerulonephritis (MGN) remain elusive. Most up-to-date concepts still rely on the rat model of Passive Heymann Nephritis that derives from an autoimmune response to glomerular megalin, with complement activation and membrane attack complex assembly. Clusterin has been reported as a megalin ligand in immunodeposits, although its role has not been clarified. We studied renal biopsies of 60 MGN patients by immunohistochemistry utilizing antibodies against clusterin, C5b-9, and phosphorylated-protien kinase C (PKC) isoforms (pPKC). In vitro experiments were performed to investigate the role of clusterin during podocyte damage by MGN serum and define clusterin binding to human podocytes, where megalin is known to be absent. Clusterin, C5b-9, and pPKC-alpha/beta showed highly variable glomerular staining, where high clusterin profiles were inversely correlated to C5b-9 and PKC-alpha/beta expression (P=0.029), and co-localized with the low-density lipoprotein receptor (LDL-R). Glomerular clusterin emerged as the single factor influencing proteinuria at multivariate analysis and was associated with a reduction of proteinuria after a follow-up of 1.5 years (-88.1%, P=0.027). Incubation of podocytes with MGN sera determined strong upregulation of pPKC-alpha/beta that was reverted by pre-incubation with clusterin, serum de-complementation, or protein-A treatment. Preliminary in vitro experiments showed podocyte binding of biotinilated clusterin, co-localization with LDL-R and specific binding inhibition with anti-LDL-R antibodies and with specific ligands. These data suggest a central role for glomerular clusterin in MGN as a modulator of inflammation that potentially influences the clinical outcome. Binding of clusterin to the LDL-R might offer an interpretative key for the pathogenesis of MGN in humans.

Circulating anti-actin and anti-ATP synthase antibodies identify a sub-set of patients with idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (iNS) with resistance or dependence to steroids is a common disease in children but in spite of an increasing clinical impact its pathogenesis is unknown. We screened for the presence of circulating antibodies against glomerular (podocytes, mesangium) and tubular cells (tubular epithelia) a cohort of 60 children with iNS including 8 patients with a familial trait of iNS or with proven mutation of NPHS1-NPHS2 and 12 with good sensitivity to steroids. Positive sera were found in 8 cases, all belonging to the category without familial trait/molecular defects. The targets of antibodies were characterized with Western blot and MALDI-Mass utilizing beta-hexyl cell extracts separated with two-dimensional electrophoresis. In all cases antibodies of the IgM class were directed against ATP synthase beta chain alone (4 cases) or in combination with actin (3 cases); one child presented IgG against aldose reductase. The clinical picture was nephrotic syndrome with steroid resistance or dependence and variable cyclosporin sensitivity; 3 patients developed end stage renal failure. The basic pathology picture was focal segmental glomerulosclerosis (FSGS) in 4 cases and mesangial proliferative glomerulonephrites with deposition of IgM in 2. Overall, patients with circulating auto-antibodies could not be readely differentiated on clinical grounds with the exception of 3 children who developed positivity for antinuclear antibodies during the follow-up. Affinity-purified IgM from one patient who underwent plasmapheresis for therapeutical pourposes (but not from a normal pool) induced proteinuria in Sprague-Dawley rats and concomitant human IgM deposition within glomeruli. This is the first report of circulating anti-actin/ATP synthase beta chain antibodies in a subset of patients with iNS. Both pathological significance and clinical impact given by the presence of these antibodies and the relationship with other conditions such as lupus-erythematosus, characterized by their presence, must be defined.

Nuclear translocation of a clusterin isoform is associated with induction of anoikis in SV40-immortalized human prostate epithelial cells

Clusterin gene expression is potently induced in experimental models in which apoptosis is activated, such as rat prostate involution following castration. Nevertheless, its precise physiological role has not yet been established, and both anti-apoptotic and pro-apoptotic functions have been suggested for this gene. Clusterin expression level depends on cell proliferation state, and we recently showed that its over-expression inhibited cell cycle progression of SV40-immortalized human prostate epithelial cells PNT2 and PNT1a. Here we studied clusterin expression in PNT1a cells subjected to serum-starvation with the aim of defining clusterin early molecular changes following apoptosis induction. Under serum-starvation conditions, decreased growth rate, slow rounding-up of cells, cell detachment, and formation of apoptotic bodies indicative of anoikis (detachment-induced apoptosis) were preceded by significant downregulation of 70 kDa clusterin precursor and upregulation of 45-40 kDa isoforms. On the 8th day of serum-free culturing, only the higher molecular weight protein-band of about 45 kDa was clearly induced and accumulated in detached cells and apoptotic bodies in which PARP was activated. Anoikis was preceded by induction and transloction of a 45-kDa clusterin isoform to the nucleus. Thus, nuclear targeting of a specific 45-kDa isoform of clusterin appeared to be an early and specific molecular signal triggering anoikis-death. Considering also that clusterin is downregulated during prostate cancer onset and progression, and that its upregulation has inhibited DNA synthesis and cell cycle progression of immortalized human prostate epithelial cells, we suggest that clusterin might be a new anti-oncogene in the prostate.

Preoperative Prediction of Pathological Stage by Quantitative Histology in 102 Patients with Prostate Cancer (PCa) and Serum PSA ≤10 ng/mL

Purpose. To find a predictor of extraprostatic extension in clinically localized prostate cancer (PCa), preoperative ultrasound-guided prostate needle biopsies and clinicopathological data were reviewed.

Materials and Methods

102 consecutive patients (median age 63 years) with serum PSA ≤10 ng/mL who underwent radical retropubic prostatectomy were included. Preoperative prostate biopsies according to an extended protocol were performed and whole-mount prostatectomy specimens were processed. One or more of the following biopsy variables were considered predictive of locally andvanced PCa: more than 2/12 cancer-positive cores, total percentage of cancer (TPC) >20%, greatest percentage of cancer (GPC) >50%, bilateral PCa, presence of cancer in both lateral portions, Gleason score >6.

Results

Only 32/102 (31.4%) specimens showed an organ-confined PCa; the remaining were pT3a in 30 (29.4%) cases, pT3b in 6 (5.9%) and pT2–T3 with positive surgical margins in 34 (33.3%). Quantitative histology predicted an organ-confined PCa in 41.2% of patients. In all 102 patients and in 56 with T1c clinical stage, the positive predictive value (PPV) and negative predictive value (NPV) of biopsy findings, to predict an organ confined PCa, was 81.2 vs 92% and 91.6 vs 93.4%, respectively. The PPV and NPV to predict a locally advanced PCa was 92.8 and 86.5%, respectively.

Conclusions

Quantitative histology seems to be helpful for locally staging of PCa in patients with T1c clinical stage and PSA ≤10 ng/mL.

Humoral permeability factors in the nephrotic syndrome: a compendium and prospectus

The concept that increased glomerular albumin permeability in steroid-resistant nephrotic syndrome is induced by circulating humoral factors is not new. Zimmermann (1) was among the first to demonstrate that serum from a renal transplant patient with recurrent focal segmental glomerulosclerosis (FSGS) could provoke increased albumin excretion when infused in the aorta of intact rats. Unfortunately, the experiment was not easily reproducible, and the possibility that human serum could induce serum sickness in rats was a serious limitation of the original experiment. We now know that inhibitors of permeability activity are present in both normal human and rat serum (see below), which explains the difficulty in replicating the disease in intact animals. In 1974 Shalhoub (2) theorized that a disordered clone of T lymphocytes, present in both minimal change disease and FSGS, secreted a circulating lymphokine "toxic" to the glomerular barrier. In support of this hypothesis, Koyama et al (3) formed hybridomas from T cells from four patients with minimal change disease and three control subjects. The hybridomas of the patients produced a substance that induced proteinuria when injected intravenously into normal rats. However, the study utilized stimulated and not quiescent T cells, and therefore the relevance to the pathogenesis of FSGS is unknown. Hoyer and colleagues first described recurrence of idiopathic nephrotic syndrome after renal transplantation in 1972 (4). Numerous subsequent reports have established the rate of recurrence as being about 30%. Timely plasmapheresis associated with aggressive immunosuppression resolves the proteinuria and disease progression in a large proportion of cases (5). FSGS not only recurs after renal transplantation, but the diseased kidney can also recover when kept protected from the pathological milieu. Rea et al (6) demonstrated that kidneys from a donor with FSGS transplanted into two uremic recipients were free from proteinuria, and that renal function was normal after one year. Ethical and legal considerations aside, recurrence of FSGS after transplantation is strong evidence supporting the role of a humoral factor in the pathogenesis of the disease.

Inhibition of renal permeability towards albumin: a new function of apolipoproteins with possible pathogenetic relevance in focal glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a degenerative renal disease characterized by the accumulation of extracellular matrix and lipids within the glomerular tuft. It has been proposed that an abnormal renal permeabilization towards proteins induced by a putative plasma factor is, in some way, involved in the pathogenesis of the disease. In this paper, we measured the plasma permeability activity (Palb) in several sera of patients with FSGS and found a mean activity of 0.82+/-0.03 which means a marked increase compared to a mean Palb of 0.16+/-0.03 in normal controls. Coincubation of FSGS and normal serum reduced the permeability activity within the normal range; normal serum added to the incubation medium after the glomeruli had already been exposed to the FSGS serum had no effect, suggesting the presence of inhibitory substances with a direct effect on a circulating substrate. Finally, the antipermeability activity was retained when heated to 60 degrees C but not to 100 degrees C. By serial fractionations of normal serum and reported activity measurements at each step, five natural occurring inhibitors of albumin permeabilization were purified and characterized by matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS), as components of apolipoproteins (apo) (apo E2 and E4, apo L, the high Mr apo J and a 28 kDa fragment of apo A-IV). Coincubation of each apolipoprotein with FSGS serum inhibited permeability, but only apo J and apo E2 and E4 were found to be crucial for the process. In conclusion, we have purified from normal serum five inhibitors of permeability induced by FSGS serum, all corresponding to apolipoproteins. An imbalance between permeability factors and apolipoproteins may play a pathogenetic role in FSGS.

New high-performance liquid chromatographic method for the detection of picolinic acid in biological fluids

A HPLC method is described to quantify picolinic acid in milk, blood serum and tissue culture supernatant. The method requires very little sample preparation because acid precipitation allows total recovery of picolinic acid. High specificity and sensitivity were obtained using ion-pair chromatography on a C18 reversed-phase column with tetrabutylammonium hydrogen sulfate as ion pairing reagent. We describe the conditions for the automated testing of multiple samples and for the detection of L-tryptophan and L-kynurenine together with picolinic acid. This system will be utilized to elucidate the relationship between picolinic acid production and human disease. Furthermore, we provide the first evidence of picolinic acid in human blood serum.

Analytical titration curves of glycosyl hydrolase Cel45 by combined isoelectric focusing-electrophoresis

The electrical charge of endocellulase Cel45-core has been determined by combined isoelectric focusing-electrophoresis in the range of pH 3-9. In order to transform electrophoretic mobility to absolute electrical charge value, several corrections were applied: the frictional coefficient theoretically calculated from the molecular dimensions depends on porous gel structure and on the ionic strength of the solution. By comparing the curve calculated according to the Linderstrom-Lang equation, the number of charged electrical groups exposed to the solvent and their apparent ionization constants, pK(o)i, can be determined. Furthermore, the macromolecule structure can be assumed not to change in this pH range. This finding is necessary to understand the structure and the electrical properties of the entire Cel45 molecule.

Identification of HSP-60 as the specific antigen of IgM produced by BRG-lymphoma cells

In previous studies we described a patient with Burkitt's lymphoma and AIDS, whose cells recognized a molecule expressed by normal and malignant breast cells. In the present study, we identified this antigen by two-dimensional (2-D) electrophoresis and Western blotting using the antibody produced by lymphoma cells. The antigen so identified consisted of two clusters of spots with a molecular mass (Mr) of 60 and 50 kDa, respectively. Preparative immobilized pH gradient (IPG) was subsequently used to isolate the clusters of spots of higher molecular masses, from which peptide fragments of approximately 10 aa were separated on reverse-phase chromatography and sequenced. This procedure enabled the identification of the antigen recognized by the lymphoma cells as HSP-60. By means of serological analyses it was possible to identify the lower molecular mass cluster of spots as a molecule related to HSP-60. It is hypothesized that this molecule is a membrane form of HSP-60 that differs from HSP-60 in a COOH terminal portion.

Rapid detection of gammaT cell receptor gene rearrangements in acute lymphoblastic leukemia by electrophoresis and silver staining: implications for detection of minimal residual disease

Minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL) was studied using polymerase chain reaction (PCR). GammaT cell receptor (TCRG) genes are ideal targets for PCR-based detection of MRD due to their molecular characteristics. Polyacrylamide gel electrophoresis (PAGE) analysis of PCR products followed by silver staining was performed for 72 children with ALL at the onset of disease. Silver staining is an effective technique to detect gene rearrangements without the use of ethidium bromide. Moreover, this method may show heteroduplex bands of a clonal nature when both TCRG alleles are rearranged. PCR products subjected to a rapid staining protocol were recovered from the gel, reamplified by a second PCR and directly sequenced. After sequencing, we identified the junctional region and obtained patient-specific probes. In more than half of the patients we detected TCRG rearrangements that were used as molecular markers for residual disease.

Resolution of fibronectin and other uncharacterized proteins by two-dimensional polyacrylamide electrophoresis with thiourea

Several proteins, which are recognized components of serum, are not resolved by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) under standard conditions. One major example is fibronectin, which is detected in fairly high concentration (milligram range) by immunoassays, while undetectable in 2D-PAGE gels. Following several experiments with a combination of zwitterionic and chaotropic substances we obtained a good resolution of the protein in gels containing 0.5 M thiourea plus 8 M urea. By this technique, fibronectin was, for the first time, found to be microheterogeneous between pl values of 5.3 and 5.6. Besides fibronectin we detected three other families of uncharacterized proteins with Mr of 130000, 110000 and 34000 respectively, whose identity and function are currently under investigation.

alpha 1-Antitrypsin (AAT) deficiency and ANCA-positive systemic vasculitis: genetic and clinical implications

A high incidence of alpha 1-antitrypsin (AAT) deficiency has been reported in patients with C-ANCA systemic vasculitis in association with antibodies against proteinase-3 (PR3). To clarify the role of AAT deficiency in the acute vasculitic process as well as in progression of the disease, we studied 84 patients with either C-ANCA or P-ANCA vasculitis with special reference to: (a) the AAT gene, (b) the phenotypic (Pi) variants and (c) the serum levels during both acute illness and remission. The PiZ gene was found in six patients (8% vs. 1.5% controls) irrespective of the type of autoantibodies (C-ANCA vs. P-ANCA). All PiZ patients displayed the ability to raise their AAT serum levels up to the normal range during acute illness. In contrast, 24 patients with the PiM phenotype presented low AAT serum levels during acute illness. In all these patients, the AAT levels returned to normal values during the remission. Low AAT levels were associated with low levels of C-reactive protein (PCR) (P < 0.001), with a less severe renal involvement or a minor risk of death, and, in one tested patient, with a novel point mutation (TCGA-->TCAA) at the enhancer-promoter region of the AAT gene. Low AAT serum levels did not correlate with either type/titre of autoantibody or distribution/severity of the vasculitis process. In the case-control study, high AAT levels emerged as a major determinant of progression towards end-stage renal failure [odds ratio 3 (95% CI 1.1-8.4)]. These results indicate: (a) a high incidence of the PiZ gene of AAT in systemic vasculitis irrespective of the type of autoantibodies; (b) a novel form of AAT deficiency associated with the normal PiM phenotype becoming manifest only during acute illness; (c) dysregulation of the acute-phase response affecting selectively AAT or both AAT and PCR; (d) correlation between low plasma levels of AAT and less severe renal involvement or risk of death.

Negative staining of proteins in polyacrylamide gels with methyl trichloroacetate

This paper describes a new, sensitive (in the nanogram range), and rapid (two-step) technique for the negative staining of proteins in polyacrylamide gels in the presence or absence of sodium dodecyl sulfate. After separation, gels are incubated with 8% methyl trichloroacetate ester in 38% isopropanol and then washed in water to produce a negative image of colorless proteins against an opaque background. The technique allows unmodified proteins to be recovered for biological studies or transblot for amino acid sequence. Finally, owing to the reversibility of the process, gels can be restained after rapid visualization. For these reasons, negative staining with methyl trichloroacetate should become the method of choice for rapid and sensitive staining of proteins prior to further processing, including stable staining with silver ions.

Purification of alpha-1-antitrypsin monomer by preparative electrophoresis

Alfa-1-antitrypsin (alpha 1AT) was purified by pseudoligand chromatography and preparative electrophoresis from the serum of a patient with alpha 1AT deficiency. The combination of the two techniques yielded a high grade batch of alpha 1AT monomer and this was successfully used to purify the protein from the serum of PiMIM1, PiMIM2, and PiZZ phenotype subjects. This procedure should facilitate structural studies of alpha 1AT variants susceptible to intracellular accumulation.

Intact renal albumin downregulates the extracellular matrix expression by mesangial cells and renal fibroblasts in vitro

Chronic Adriamycin (ADR) nephropathy is invariably associated with glomerulosclerosis and tubulointerstitial fibrosis. To investigate the hypothesis that severe albuminuria plays a role in the pathogenesis of both processes, we purified the protein from conditioned media of rats with advanced ADR nephropathy and tested the fibrogenic effect on renal fibroblasts and mesangial cells in vitro. Albumin was purified by pseudoligand chromatography and was identified on the basis of the NH2 amino terminus. Furthermore, it was differentiated from the urinary homologue, being more anionic and more fatted while maintaining a conserved peptide composition. The exposure of renal cells to renal albumin induced a dose-dependent reduction in collagen synthesis with a half-maximal decrease with 0.2 microgram/ml of albumin. With renal albumin levels of 0.4 microgram/ml the collagen incorporation of 3H-proline by mesangial cells and renal fibroblasts (primary cultures and cell lines) was reduced by 76, 81 and 45% respectively. A qualitative analysis by SDS-polyacrylamide electrophoresis and immunoprecipitation of radiolabelled collagens demonstrated a drastic and unselective decrease in all major collagens synthesized by mesangial cells and fibroblasts, including type I, III and V. Previous immunoprecipitation of the protein with anti-rat albumin antibodies completely reversed this phenomenon. Finally, albumin purified from urines of rats with ADR nephropathy downregulated the synthesis by renal cells of the same collagens but this effect was less evident compared to renal albumin. These findings demonstrate that renal albumin drastically reduces the synthesis of collagens by mesangial cells and renal fibroblasts, this effect being most evident on those components which constitute the extracellular matrix in glomerulosclerosis and interstitial fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracellular matrix formation by epithelial cells from human polycystic kidney cysts in culture

Cells from the cysts of patients with autosomal dominant polycystic kidney disease (PKD) were grown in vitro under standard conditions without the aid of collagen-pretreated surfaces, and both the synthesis and composition of the extracellular matrix were investigated. At confluence, PKD cells presented the typical features of epithelial cells, but showed a different collagen composition from fibroblasts. Compared with normal tubular epithelia (NTE), PKD monolayers produced an excess of extracellular matrix, which accounted for 30% of the total incorporation of [3H] proline, although this value was considerably lower (by a factor of 10) in the case of NTE. Immunohistochemical and electrophoretic techniques revealed a complex collagen composition in the extracellular matrix which included [alpha (III)]3 and collagen IV. However, part of the collagen components remained unidentified in spite of the fact that they exhibited a typical M(r) of alpha 1(I) and alpha 2(I) in the presence of urea. Immunoprecipitation with monospecific antibodies and Northern blotting with specific probes failed to recognize alpha 1(I) and alpha 2(I), but demonstrated their presence in fibroblasts. Purification and cyanogen bromide digestion demonstrated a strong interhomology in fingerprint peptide composition among the uncharacterized collagens synthesized by PKD cells, thus suggesting a common identity. These observations document a markedly augmented production of extracellular matrix by PKD cultured cells in vitro, and show the presence of collagens which do not share homologies with the major collagen molecules. A better characterization of extracellular matrix composition is central to any comprehension of the cytogenetic mechanisms in vivo.

Mapping of the human COL5A1 gene to chromosome 9q34.3

A 353-bp region encoding for the NH2 terminus of the noncollagenic part of the alpha 1(V) chain was amplified by the polymerase chain reaction (PCR), subcloned and sequenced. The subcloned PCR product (pGC1) presented the same nucleotide sequence as the original fragment from the published sequence of COL5A1. In situ hybridization, using pGC1 as a probe, mapped the COL5A1 gene to chromosome 9q34.3. This assignment shows that COL5A1 is not synthetic with COL5A2, which is localized together with other collagen genes on chromosome 2.

Differential scanning calorimetry characterization of rabbit brain membrane fractions

Various membrane fractions have been prepared from rabbit brain synaptosomes by centrifugation on discontinuous sucrose gradients after osmotic shock. These fractions were characterized by electron microscopy (E.M.), SDS-PAGE and GABA binding. The fractions were then studied by differential scanning calorimetry (DSC). The calorimetric results indicate that all the fractions studied show thermal transitions at around 60 degrees C which correspond to the "melting" of membrane structures. An additional transition at higher temperature (82 degrees C) seems to be associated with an enrichment in central myelin fragments.

Puromycin aminonucleoside metabolism by glomeruli and glomerular epithelial cells in vitro

Two puromycin aminonucleoside (PAN) excretion products were purified by HPLC from urine of PAN-treated rats and characterized by nuclear magnetic resonance as N6-dimethyl-3'amino-3'deoxyadenosine (DA-Ado) and N6-methyl-3'amino-3'deoxyadenosine (MA-Ado), respectively, the former corresponding to unmodified PAN. DA-Ado was not a substrate for adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) or xanthine oxidase (XO), while MA-Ado was consecutively converted into hypoxanthine by a mixture of ADA and PNP. A different rate of transformation of DA-Ado and MA-Ado into hypoxanthine by isolated glomeruli was observed and was higher for the monomethylated analogue by a factor of 3 (79% vs. 21%); this was ascribed to the rate-limiting level of a demethylase activity acting on DA-Ado. Furthermore, DA-Ado was not transformed by glomerular epithelial cells in culture, while a little amount of MA-Ado was converted into hypoxanthine after six hours of incubation. In spite of this different metabolic behavior, the same order of cytotoxicity on glomerular epithelial cells in culture was observed for MA-Ado, DA-Ado and commercial PAN. All these molecules induced a dose response inhibition of [3H]thymidine incorporation into DNA after exposure for two hours and a marked alteration of cell viability which was not inhibited by free radical scavengers and deferoxamine. This study provides the first evidence for a glomerular metabolism of PAN and its urinary metabolite MA-Ado involving their transformation via the purine cycle enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction between cationic dyes and erythrocyte membranes in minimal change nephropathy: an electrophoretic approach

A study was undertaken to clarify the usefulness of two cationic dyes, alcian blue (AB) and ruthenium red (RR) in demonstrating the defect in cellular membranes noted in minimal change nephropathy (MCN). The binding of both dyes to RBC membranes purified from normal and nephrotic children was evaluated by electrophoretic titration curves. When examined separately, AB was found to precipitate spontaneously, producing macro-aggregates with no electrophoretic mobility at pH 5. This was presumed to be the result of hydrophobic interaction of the dye with itself. The same phenomenon was observed when this dye was incubated at 37 degrees C with RBC ghost's from normal children, when AB presented a sigmoidal curve with a net positive charge for pHs higher than 5.5 and lower than 5 and no electrophoretic mobility at pH 5. However, incubation of AB with RBC ghosts from children with MCN resulted in an improvement of the solubility of the dye which then migrated with a net positive charge along the whole gradient of pH from 3.5 to 9. The presence of zwitterionic neutral detergents such as CHAPS, but not of a charged substance such as protamine sulphate, inhibited precipitation at pH 5 when incubated with membranes from normal children, supporting the hydrophobic nature of the phenomenon. When RR was used instead of AB, it was fully protonated (i.e. did not precipitate) when analysed alone, but when incubated with normal RBC ghosts, it also revealed no electrophoretic mobility at pH 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary protein restriction on renal purines and purine-metabolizing enzymes in adriamycin nephrosis in rats: a mechanism for protection against acute proteinuria involving xanthine oxidase inhibition

1. A low protein diet prevents the development of proteinuria and glomerular damage in adriamycin experimental nephrosis without affecting renal haemodynamics. In this study the hypothesis was tested as to whether protein restriction is able to modulate the purine metabolic cycle and related enzymes such as xanthine oxidase, one of the putative effectors of adriamycin nephrotoxicity. 2. Renal activities of xanthine oxidase and purine nucleoside phosphorylase were markedly depressed in adriamycin-treated rats fed a 9% casein (low protein) diet compared with the group fed a 22% casein (normal protein) diet both 1 day after adriamycin administration and at the time of appearance of heavy proteinuria (day 15), whereas the activity of renal adenosine deaminase was unchanged. 3. The concentrations of the metabolic substrates of xanthine oxidase, i.e. hypoxanthine and xanthine, were constantly lower in renal homogenates of rats fed a low protein diet compared with those on a normal protein diet. In urine, uric acid, the product of hypoxanthine-xanthine transformation, was lower 1 day after adriamycin injection in protein-restricted rats compared with the group on a normal protein diet which showed a marked increase in its excretion. At the same time, the urinary efflux of adenosine 5'-monophosphate, which is the precursor nucleotide of the above-mentioned nucleosides and bases, was very high in rats fed a low protein diet, whereas it was absent in the group on a normal protein diet. 4. The progressive increment in proteinuria of glomerular origin (i.e. increased excretion of albumin and transferrin) typical of adriamycin-treated rats fed a normal protein diet was inhibited in the protein-restricted animals, which were normoproteinuric on day 10 and were only slightly proteinuric on day 15. 5. Like protein restriction, the pharmacological suppression of renal xanthine oxidase by dietary tungstate and the scavenging by dimethylthiourea of the putative free radical deriving from the action of xanthine oxidase, were associated with a similar (quantitative and qualitative) inhibition of glomerular proteinuria. 6. These data demonstrate that dietary protein restriction is associated with a block in purine metabolism within the kidney due to a marked reduction in the activities of two main enzymes of the cycle, i.e. purine nucleoside phosphorylase and xanthine oxidase, the latter being a putative effector of adriamycin nephrotoxicity. The partial reduction of proteinuria induced by a low protein diet is quantitatively and qualitatively comparable with the reduction induced by the specific block of renal xanthine oxidase or by the scavenging of OH.deriving from hypoxanthine and xanthine transformation.(ABSTRACT TRUNCATED AT 400 WORDS)

Purification of proteinase-free collagenase from commercial batches of the enzyme

A method is described for purifying a collagenase fraction from commercial batches of the enzyme, which is free of proteolytic effects. The method, which is based on preparative electrophoresis in discontinuous buffers followed by electroelution, enables the separation and purification of 6 collagenase fractions with a good recovery of the protein (approximately 80%). Proteinase activity was a peculiarity of the low molecular weight components whereas one high MW fraction (C2) had maximal collagenase activity but was free from aspecific proteolytic effects. Only this collagenase should be employed for molecular studies on the collagen composition of the basement membrane.

Urinary excretion of brush-border antigen and plasma proteins in early stages of diabetic nephropathy

In 109 patients with insulin-dependent diabetes mellitus (IDDM), we measured the urinary excretion of albumin, the low molecular weight proteins (LMWP) retinol-binding protein (RBP) and beta 2-microglobulin (beta 2m), and brush-border antigens (BBA) revealed by monoclonal antibodies. All such markers of kidney damage and/or dysfunction were higher in diabetic patients than in 44 controls. Increased urinary levels of BBA (p = 0.0001) were associated with higher values of albumin (p = 0.0002), RBP (p = 0.0005) and, to a lesser extent, of beta 2m (p = 0.1), different combinations of values above the reference limits being observed. Some 30 and 40% of patients with and without microalbuminuria, respectively, also exhibited signs of tubulopathy. Although under certain circumstances tubular defects may give rise to small increases in albuminuria, the most likely explanation for our findings is the coexistence of glomerular and tubular damage in some patients with IDDM. Neither the prognostic value nor the pathophysiological meaning of tubular damage and/or dysfunction can be assessed by the present study, owing to its cross-sectional design. Tubular markers thus deserve further studies to clarify whether in diabetic patients they indicate a more severe or diffuse kidney impairment.

Hypertension and renal selectivity properties in diabetic microalbuminuria

The renal selectivity properties towards albumin were evaluated in ten diabetic patients with arterial hypertension before and after the pharmacological normalisation of blood pressure, and were compared to 12 subjects with essential hypertension. While all patients of the control group were normoalbuminuric during hypertension, six of the diabetic group were microalbuminuric when hypertensive and became almost normoalbuminuric after blood pressure pharmacological control. All microalbuminuric diabetic patients presented altered properties of renal selectivity as epitomised by a non-preferential urinary excretion of glycosyl albumin (GA) (urinary GA/serum GA less than or equal to 1). At variance the selectivity properties were normal in normoalbuminuric diabetic patients and in essential hypertension. It was concluded that in diabetes mellitus arterial hypertension is associated with microalbuminuria when the renal properties of selectivity are altered, but does not implicate any proteinuric effect in those cases where the GBM function is preserved.

Low-protein diet and xanthine-metabolising enzymes in adriamycin nephrosis

Proteinuria and renal xanthine metabolising enzymes, xanthine oxidase and xanthine dehydrogenase, were evaluated in Adriamycin-treated rats fed standard (21% casein) and low-protein (6% casein) diets. In rats fed a standard diet Adriamycin was associated with increased activities in the kidney of xanthine oxidase and xanthine dehydrogenase and induced massive proteinuria. The pharmacological block of both enzymes by allopurinol and tungsten block of both enzymes by allopurinol and tungsten reduced proteinuria to one-third of the original levels. Rats fed a low-protein diet presented decreased levels of renal xanthine oxidase and xanthine dehydrogenase and were only slightly proteinuric. Finally, rats shifted from a low-protein diet to a normal one developed massive proteinuria in spite of normal or slightly decreased levels of renal xanthine oxidase and xanthine dehydrogenase. We conclude that a low-protein diet is effective in decreasing the levels of xanthine metabolising enzymes that are in part responsible for the renal damage due to Adriamycin. This is not however the unique mechanism by which the low-protein diet protects against the development of proteinuria in Adriamycin nephrosis; other factors must also be hypothesised.

Tubular epithelium culture from nephronophthisis-affected kidneys: a new approach to molecular disorders of tubular cells

Abnormalities of tubular membrane structure and composition have been proposed as the primary defect in nephronophthisis (NEF). In order to characterize the protein composition of tubular cells in NEF, in vitro methods were developed to culture and propagate tubular cells obtained from biopsy fragments. Accordingly, microdissected cortical slices (1 x 3 mm) were first digested with collagenase and DNAse and then grown in RPMI medium supplemented with 10% NU serum and conditioned serum deriving from 3T3 cultures. At confluence, cultured cells from NEF showed characteristics which were typical of normal tubules, i.e. presence of cytokeratin and positivity for succinic dehydrogenase and alkaline phosphatase stainings, and presented no morphological alterations compared to cultured cells from normal tubular epithelium. Moreover, no difference was observed for fibronectin, collagen IV and laminin stains. Analysis by two-dimensional electrophoresis of cellular extracts revealed several changes in protein composition of NEF, the main one being the decrease in NEF cells of a polypeptide with a molecular weight of 120 kD and a pI of 4.8; this polypeptide was a constant finding in normal kidneys. These observations demonstrated that human tubular epithelial cells can be successfully cultured from very small biopsy fragments, which represents a new approach to the study of molecular disorders involving tubular cells in inherited disease. Cultured cells from NEF maintain the same morphological, immunological and cytochemical characteristics as normal tubular cells, but present a few alterations in polypeptide composition which may have pathogenetic relevance. A more careful analysis of these alterations is needed to define the molecular disorder(s) involving the tubule in NEF.

Endogenous albumin as a marker of renal selectivity in steroid-unresponsive nephrotic syndrome

Albumin electrical charge, conformation and hydrophobicity taken as indexes of renal selectivity were evaluated in 8 children affected by steroid-unresponsive nephrotic syndrome associated with glomerulosclerosis or mesangial hypercellularity. These characteristics related to urinary albumin have already been reported to vary markedly in steroid-responsive nephrotic syndrome of minimal-change nephropathy giving rise to new pathogenetic possibilities in this disease. In the steroid-unresponsive nephrotic children albumin was found to be more microheterogenous and cationic in urine than in serum and at the same time it was conformationally altered. Regarding these characteristics, the selectivity properties of the renal filter are similar in steroid-unresponsive nephrotic syndrome, suggesting a pathogenetic connection between these two renal disorders.

Peroxidative damage of the erythrocyte membrane in children with nephrotic syndrome

The structural composition of erythrocyte ghosts was analysed in children affected by steroid-responsive (SRNS) and unresponsive nephrotic syndrome (SUNS). No variation of either intrinsic or extrinsic ghost proteins was found by discontinuous SDS-electrophoresis associated with a very sensitive double staining technique. By contrast, the composition of inner-layer phospholipids--phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS)--was altered in SRNS with minor changes also involving phosphatidic acid, phosphatidyl inositol and lysophosphatidyl choline. Signs of peroxidative damage were present in both SRNS and SUNS ghosts and inside the cells; these included high levels of fluorescent amino-iminopropene derivates of PE and PS, increased intraerythrocytic amounts of malonyldialdehyde and decreased levels of reduced glutathione. Taken together these results support the concept that in SRNS and SUNS erythrocytes are target cells for peroxidative damage. In SRNS peroxidation of membrane lipids results in a marked alteration of the phospholipid composition of erythrocyte ghosts.

Preparative high performance chromatography of a major browning compound derived from lysine and glucose

A major browning compound derived from lysine and glucose was purified by high performance chromatography on a RP8 column after several extractions in methanol plus acetonitrile. This compound was separated by a main contaminant corresponding to unreacted lysine by extracting the aminoacid after its derivatization with ninhydrin.

Reaction of 2-amino-2-deoxy-D-glucose and lysine: isolation and characterization of 2,5-bis(tetrahydroxybutyl)pyrazine

The reaction of 2-amino-2-deoxy-D-glucose with lysine in water under simulated physiological conditions gave several browning products, with characteristic optical (lambda max 340 nm) and fluorescent properties (emission at 430 nm for excitation at 362 nm). The major product was isolated and characterized by mass spectrometry and n.m.r. spectroscopy as 2,5-bis(tetrahydroxybutyl)pyrazine derived by the condensation of two molecules of 2-amino-2-deoxy-D-glucose.