Cryptomphalus aspersa mollusc eggs extract promotes migration and prevents cutaneous ageing in keratinocytes and dermal fibroblasts in vitro

BACKGROUND

The search of substances that minimize cutaneous ageing has increased in the last few years. Previous studies have described the regenerative properties of the secretion of the mollusc Cryptomphalus aspersa (C. aspersa) when applied topically.

OBJECTIVE

We evaluate the in vitro effects of a new product derived from the eggs of C. aspersa, IFC-CAF, on cell proliferation, migration, distribution of cytoskeletal proteins, production of extracellular components as well as its ability to prevent cutaneous ageing because of intrinsic or extrinsic factors (exposure to UVB) by determination of ageing markers.

METHODS

We have used the human keratinocyte cell line (HaCaT cells), primary dermal fibroblasts (HDF) and senescent dermal fibroblasts (SHDF). The effects of the compound on cell proliferation and on the cell cycle were determined by the MTT colorimetric assay, estimation of total protein and/or trypan blue test and by flow cytometry, respectively. We also studied cell migration using the wound-healing migration assay, whereas ELISA assays, Western Blot and immunofluorescence microscopy were carried out to test the expression of proteins related to cytoskeleton, extracellular matrix and with ageing.

RESULTS

We have found that IFC-CAF does not promote proliferation but induces migration of HaCaT, HDF and SHDF in a time- and dose-dependent manner; a better organization of cytoskeletal proteins (F-actin and vimentin) and promotes the production of extracellular components (fibronectin, collagen 1 and MMPs) and the adhesion to cell-substrate vinculin protein. IFC-CAF also prevents cutaneous ageing. The treatment decreases the expression of the ageing-related markers b-Gal, p53 and p16INK4 in SDDF cells, and improves cell survival after UVB irradiation and nuclear repair in HaCaT cells.

CONCLUSION

IFC-CAF has regenerative properties and protects against ageing factors being, therefore, a potential therapeutic agent for treating or preventing skin ageing.

New experimental models of skin homeostasis and diseases

Homeostasis, whose regulation at the molecular level is still poorly understood, is intimately related to the functions of epidermal stem cells. Five research groups have been brought together to work on new in vitro and in vivo skin models through the SkinModel-CM program, under the auspices of the Spanish Autonomous Community of Madrid. This project aims to analyze the functions of DNA methyltransferase 1, endoglin, and podoplanin in epidermal stem cell activity, homeostasis, and skin cancer. These new models include 3-dimensional organotypic cultures, immunodeficient skin-humanized mice, and genetically modified mice. Another aim of the program is to use skin-humanized mice to model dermatoses such as Gorlin syndrome and xeroderma pigmentosum in order to optimize new protocols for photodynamic therapy.

Novel group A rotavirus G8 P[1] as primary cause of an ovine diarrheic syndrome outbreak in weaned lambs

Rotavirus is a worldwide major cause of diarrhea outbreaks in neonatal ruminants. An outbreak of ovine diarrheic syndrome (ODS) in 50-75 days-old lambs (weaned lambs) is described. Fecal immunochromatography and intestinal immunohistochemistry for rotavirus group A were performed. In addition, semi-nested multiplex RT-PCR for G and P rotavirus genotyping in combination with sequencing were performed, to support the diagnosis and identify the viral strain. A novel ovine rotavirus group A G8 P[1] strain was determined as the main cause of the ODS observed, whereas other pathogens were ruled out.

Epigenetic control of nuclear architecture

The cell nucleus is a highly structured compartment where nuclear components are thought to localize in non-random positions. Correct positioning of large chromatin domains may have a direct impact on the localization of other nuclear components, and can therefore influence the global functionality of the nuclear compartment. DNA methylation of cytosine residues in CpG dinucleotides is a prominent epigenetic modification of the chromatin fiber. DNA methylation, in conjunction with the biochemical modification pattern of histone tails, is known to lock chromatin in a close and transcriptionally inactive conformation. The relationship between DNA methylation and large-scale organization of nuclear architecture, however, is poorly understood. Here we briefly summarize present concepts of nuclear architecture and current data supporting a link between DNA methylation and the maintenance of large-scale nuclear organization.

Epigenetic inactivation of the Wnt antagonist DICKKOPF-1 (DKK-1) gene in human colorectal cancer

Colorectal cancer is a major cause of cancer death worldwide. A number of key oncogenes and tumor suppressor genes have been proposed to drive progression from healthy colonic epithelia to malignant tumors, including members of the Wnt/beta-catenin pathway. Recently, CpG island promoter hypermethylation was shown to cause inactivation of two extracellular Wnt inhibitors in colon cancer: secreted frizzled-related proteins (sFRPs) and Wnt inhibitory factor-1 (WIF-1). Here, we show for the first time that another extracellular Wnt inhibitor, the DICKKOPF-1 (DKK-1) gene, is transcriptionally silenced by CpG island promoter hypermethylation in colon cancer cell lines (n=9), whereas treatment with the DNA-demethylating agent 5-aza-2-deoxycytidine restored DKK-1 expression. Restoration of DKK-1 function in non-expressing cells bearing a truncated APC (Adenomatous Polyposis Coli) gene had no effect on beta-catenin/T-cell factor-dependent transcription, but induced tumor suppressor-like features such as reduced colony formation density and tumor growth inhibition in nude mice. These results suggest additional functions for DKK-1 other than inhibiting canonical Wnt signaling. In primary colorectal tumors, DKK-1 was found hypermethylated in 17% (nine of 54) of cases. Furthermore, while for both SFRP-1 and WIF-1 methylation-associated silencing occurred across the whole spectrum of colorectal tumorigenesis, DKK-1 promoter was selectively hypermethylated in advanced colorectal neoplasms (Duke's C and D tumors).

Vitamin D(3) promotes the differentiation of colon carcinoma cells by the induction of E-cadherin and the inhibition of beta-catenin signaling

The beta-catenin signaling pathway is deregulated in nearly all colon cancers. Nonhypercalcemic vitamin D3 (1alpha,25-dehydroxyvitamin D(3)) analogues are candidate drugs to treat this neoplasia. We show that these compounds promote the differentiation of human colon carcinoma SW480 cells expressing vitamin D receptors (VDRs) (SW480-ADH) but not that of a malignant subline (SW480-R) or metastasic derivative (SW620) cells lacking VDR. 1alpha,25(OH)2D(3) induced the expression of E-cadherin and other adhesion proteins (occludin, Zonula occludens [ZO]-1, ZO-2, vinculin) and promoted the translocation of beta-catenin, plakoglobin, and ZO-1 from the nucleus to the plasma membrane. Ligand-activated VDR competed with T cell transcription factor (TCF)-4 for beta-catenin binding. Accordingly, 1alpha,25(OH)2D(3) repressed beta-catenin-TCF-4 transcriptional activity. Moreover, VDR activity was enhanced by ectopic beta-catenin and reduced by TCF-4. Also, 1alpha,25(OH)2D(3) inhibited expression of beta-catenin-TCF-4-responsive genes, c-myc, peroxisome proliferator-activated receptor delta, Tcf-1, and CD44, whereas it induced expression of ZO-1. Our results show that 1alpha,25(OH)2D(3) induces E-cadherin and modulates beta-catenin-TCF-4 target genes in a manner opposite to that of beta-catenin, promoting the differentiation of colon carcinoma cells.

Recycling cultured cells for immunofluorescent labeling

A method to use sequential rounds of immunofluorescent labeling in cell cultures is presented. The method is based on the utilization of a non-liquid reducing agent, sodium dithionite, in conjunction with ionic or non-ionic detergents (SDS or TX100, respectively) at room temperature. This method preserves cell morphology and substrate antigenicity, and operates through the complete extraction of most primary and secondary antibodies. Using this protocol, the sequential immunolocalization of different proteins is possible, without signal interference with previous immunolabeling rounds. In addition, the method is also useful to recycle blotted membranes in immunoblots.

Photodamage induced by Zinc(II)-phthalocyanine to microtubules, actin, alpha-actinin and keratin of HeLa cells

We have studied the photosensitizing effects of zinc(II)-phthalocyanine (ZnPc) on the cytoskeleton of HeLa cells using sublethal (10(-7) M, followed by 1 or 3 min of red light to induce 20%, LD20, or 60%, LD60, cell death, respectively) or lethal (5 x 10(-6) M and 15 min of irradiation, LD100) experimental conditions. The immunofluorescent analysis of the cytoskeleton showed a variable photodamage to microtubules (MT), actin microfilaments (AF) and intermediate filaments of keratin (KF), as well as on alpha-actinin, which was dependent on treatment conditions. Both sublethal treatments induced deep alterations on interphase and mitotic MT. The mitotic index increased with time with the maximum at 18 h (12%) or 24 h (14%) after LD20 or LD60, respectively. The alterations on AF and alpha-actinin were much more severe than those observed on KF at any evaluated time. With the exception of the KF, which remained partially organized, the MT and AF network was severely damaged by the lethal treatment. Western blot analysis for alpha-tubulin, G-actin and alpha-actinin from soluble and insoluble fractions confirmed the results observed by immunofluorescence, thus indicating that these cytoskeletal components are involved in cell damage and death by ZnPc photosensitization.

Heparan sulfate, heparin, and heparinase activity detection on polyacrylamide gel electrophoresis using the fluorochrome tris(2,2'-bipyridine) ruthenium (II)

The paper shows the ability of the fluorochrome tris(2,2'-bipyridine) ruthenium (II) (Rubipy) to detect heparan sulfate, heparin, and heparinase activity of M3 murine mammary adenocarcinoma cells as well as bacterial heparinases I, II, and III in native polyacrylamide gel electrophoresis (PAGE). The technique is based on the electrophoretic mobility of high molecular weight heparins and subsequent staining with Rubipy (50 micrograms/mL). The minimum content of heparin detected by fluorescence in a UV transilluminator was 25-50 ng. The number of Rubipy molecules bound to heparin, determined in relationship to the number of disaccharide units (DU), showed that two to six heparin disaccharide units are bound by each fluorochrome molecule. Scatchard plot analysis showed one Rubipy-binding site (Kd = (8.56 +/- 2.97) x 10(-5) M). Heparinase activity was determined by densitometric analysis of the fluorescence intensity of the heparin-containing band of the gel. While heparinase I (EC 4.2.2.7.) degraded heparin and, to a lower degree, partially N-desulfated N-acetylated heparin (N-des N-Ac), heparinase II (no EC number) could efficiently degrade heparan sulfate (HS) and partially N-des N-Ac heparin. Finally, heparinase III (EC 4.2.2.8.) degraded HS almost exclusively. Only heparin and N-des N-Ac heparin were substrates for M3 tumor cell heparinases. We describe a qualitative, sensitive and simple method to detect heparinase activity and determine its substrate specificity using Rubipy fluorescence with heparin and heparan sulfate in multiple biological samples tested in parallel.

Performance of research ethics committees in Spain. A prospective study of 100 applications for clinical trial protocols on medicines

OBJECTIVES

To review the characteristics and performance of research ethics committees in Spain in the evaluation of multicentre clinical trial drug protocols.

DESIGN

A prospective study of 100 applications.

SETTING

Forty-one committees reviewing clinical trial protocols, involving 50 hospitals in 25 cities.

MAIN MEASURES

Protocol-related features, characteristics of research ethics committees and evaluation dynamics.

RESULTS

The 100 applications involved 15 protocols (of which 12 were multinational) with 12 drugs. Committees met monthly (except one). They had a mean number of 12 members, requested a mean of six complete dossiers and nine additional copies of the protocol with a mean deadline of 14 days before the meeting. All applications were approved except three (two of the three were open-label long-term safety trials rejected by the same committee), which were approved by the other committees involved. The mean time from submission to approval was 64 days. The mean time from submission to arrival of the approval document at our offices was 85 days. Twenty-five committees raised queries for 38 of the 97 finally approved applications. Impact of evaluation fee, number of members, queries raised and experience of committees on timings were not statistically significant.

CONCLUSION

Obtaining ethical approval is time-consuming. There is much diversity in the research ethics committees' performance. A remarkable delay (> 20 days) exists between the decision and the arrival of the written approval, suggesting administrative or organisational problems.

Immediate and follow-up findings after stent treatment for severe coarctation of aorta

Experimental studies have shown that stents implanted at the aorta become incorporated within the aortic wall and can be further expanded in growing animals. Few clinical studies have shown that the stent repair of severe coarctation of aorta provides excellent initial results, and little is known on the follow-up of these patients. We assessed the immediate and follow-up results obtained in a series of 48 patients (mean age 14+/-12 years) with severe coarctation of the aorta who were treated by Palmaz stent implantation; 30 of them (63%) underwent angiographic follow-up studies at a mean of 25+/-11 months after treatment. Quantitative serial analysis of the aortogram (baseline, after treatment, and at follow-up) was performed. Significant relief (mean residual gradient 3+/-4 mm Hg) was always obtained after stent implantation. The isthmus, when hypoplastic (60%), was always expanded with the stent. One associated aneurysm became occluded after the implant. Complications included aortic disruption, stent migration, and decreased or absent femoral pulses. At angiographic follow-up, the stent remained always in place, without recoil. In 22 patients (73%), there were no detectable neointimal proliferation at late angiogram; however, 8 patients (27%) had some degree of intimal thickening (1 to 5 mm), causing mild restenosis in 3 patients treated at early age, and nonsignificant lumen reduction in 5. The serial aortogram analysis revealed a minor but significant increase in nonstented aortic diameters that seemed related to the normal growth of children. No need for stent reexpansion was observed at 2-year follow-up (mean). Two patients (7%) developed late small aneurysm formation at the stented wall; both were occluded by the insertion of coils through the stent orifices. We conclude that stent treatment for severe coarctation of aorta provides excellent immediate and long-term results in young adults and children. However, at early age, restenosis by intimal growth may develop.

Fluorescence microscopy of rat embryo sections stained with haematoxylin-eosin and Masson's trichrome method

The fluorescence pattern induced by haematoxylin-eosin (HE) and Masson's trichrome (MT) staining methods on paraffin sections of rat embryos (from 13 to 18 days old) has been studied. Using optimal excitation (green light, 545 nm), HE- or MT-stained sections showed a selective red emission of the acidophilic tissue components, which was due to eosin Y in the case of HE and to acid fuchsin and/or xylidine ponceau in the case of MT. The fluorescence intensity induced by these anionic dyes was variable and related to the substrate nature and the embryo age. Whereas in young embryos only the immature red blood cells showed a noticeable fluorescence, in the oldest embryos there were also other tissue components that selectively fluoresced with these dyes, in particular fibre lens cells, elastic fibres, zymogen granules and muscle cells. Spectrofluorometric studies on free dyes and densitometric analysis of protein blots confirmed microscopical observations. Our results indicate that the standard HE and MT staining methods can be used in recognizing the appearance of specific protein structures in embryonic tissues by means of fluorescence microscopy.

[Efficiency of investigators in recruitment of patients for clinical trials: apropos of a multinational study]

BACKGROUND

Performance and efficiency in patient selection are essential for conducting clinical trials. Data on these are presented from a multinational trial.

PATIENTS AND METHODS

A randomized, double-blind, placebo-controlled, parallel-group study in asthma, with a screening phase followed after randomization by a treatment period, was selected. Number of patients screened and randomized by centre and country, centres achieving the minimum recruitment (> or = 10 patients randomized), and efficiency of investigators (randomized/screened x 100) were determined and compared.

RESULTS

564 patients, out of 836 screened, were randomized at 69 centres in 11 countries. Twenty-four centres (35%) randomized > or = 10 patients each, accounting for 70% (n = 395) of the total number recruited. Efficiency was significantly higher among these "high-performance" centres (81.4%; p < 0.001; OR, 4.7; CI 95%, 3.4-6.5) than in the remaining ones (48.1%). Five countries had > or = 2 "high-performance" centres. Efficiency was also significantly higher (p < 0.001) among those (370 randomized/455 screened, 82.1%) than in the remaining centres of the same countries (82/140; 58.6%; OR, 3.0; CI 95%, 2.7-4.7). A relevant number of centres (n = 17; 25%) randomized 0-1 patient (7 randomized/58 screened).

CONCLUSION

The analysis of patient selection in clinical trials showed that a minority of centres accounted for most of the patients recruited. Those are not only the most productive (more patients randomized) but also the more efficient (better quality of screening process).

Fluorescent cytochemistry of acid phosphatase and demonstration of fluid-phase endocytosis using an azo dye method

The aim of this work was the development of a fluorescent microscopy technique to visualize acid phosphatase activity in living and pre-fixed cells. We have shown that a coupling azo dye method, using naphthol AS-MX phosphate (NP) as substrate and fast red TR (FR) as a diazonium salt coupling agent, gives rise to a fluorescent azo dye reaction product which permits a highly sensitive demonstration of lysosomal acid phosphatase in both living and pre-fixed monolayer cell cultures. The granular staining is prevented by inhibition of acid phosphatase activity using fluoride and/or orthovanadate in both living and pre-fixed preparations. Lysosomal staining in living cells is also abolished by inhibition of fluid-phase endocytosis using low temperatures or inhibition of oxidative phosphorylation. It was shown that whilst NP entered living cells by passive diffusion, occurrence of FR in lysosomes resulted from fluid-phase endocytosis. Spectroscopic analysis of the emission and absorption features of FR, NP, naphthol AS-MX (N), and the N-FR azo dye reaction product in solution corroborated our microscopic results. The differing uptake mechanisms, and the occurrence of lysosomally localized azo dye, were also in keeping with the predictions of quantitative structure-activity relationship models of this system.

New cationic fluorochromes from diaryloxazole scintillators: fluorescence of chromatin DNA induced by N-quaternary POPOP derivatives

N-quaternary derivatives of the diaryloxazole scintillators POPOP and dimethyl-POPOP (dmPOPOP) in chloroform solution were obtained by methylation with dimethylsulfate. After drying, aqueous solutions of the corresponding oxazolium compounds (Q-POPOP and Q-dmPOPOP) revealed strong fluorescence (peaks at 485 and 493 nm, respectively). Under 365 nm excitation, both N-quaternary derivatives induced a bright greenish blue fluorescence in nuclei of chicken erythrocytes and human buccal cells, as well as in the kinetoplast DNA of Trypanosoma cruzi epimastigotes; mouse mast cell granules showed a green-yellow metachromatic emission. Chromatin fluorescence was dependent on the presence of DNA; it was abolished by washing with a 10 mM solution of the bisguanidine compound Phenformin, whereas 1 M NaCl or MgCl2 had no effect. The oxazolium derivatives were hydrophilic (log P: -6.409 and -5.373 for Q-POPOP and Q-dmPOPOP, respectively). Molecular modelling studies revealed that these cationic and non-rigid (cis) scintillator derivatives are well suited to locate along the convex floor of the narrow DNA minor groove from adenine-thymine regions.

Fluorescence of eosinophil leucocyte granules induced by 1-hydroxy-3,6,8-pyrenetrisulfonate. Visualization of differences in protein isoelectric points

After treatment of horse, rat and human blood smears with alkaline solutions of 1-hydroxy-3,6,8-pyrenetrisulfonate (HPTS), eosinophil leucocyte granules were the unique cell components which showed a bright green fluorescence. When stained with HPTS at pH 10, the whole granule of horse eosinophils showed high emission which strongly diminished after washing or staining in salt solutions or by using blocking methods for amino groups. Using HPTS at pH 12, the fluorescence reaction of horse granules was specifically located in the peripheral region, appearing as fluorescent rings. These microscopic observations, which indicate differences in the isoelectric point of proteins within the eosinophil granule, were also confirmed by HPTS staining of protein blots as model substrates. Spectral analysis of HPTS at pH 10 and 12 showed practically identical absorption and emission spectra with peaks at 450 nm and 510 nm, respectively. Our results indicate that mainly ionic binding occurs between cationic proteins and HPTS in alkaline solution, and that the most cationic proteins (with isoelectric points at pH higher than 12) are located in the peripheral annular region of horse eosinophil granules.

Cytochemical application of tris (2,2'-bipyridine) ruthenium (II): fluorescence reaction with sulfated polyanions of mast cell granules

We describe the use of tris (2,2'-bipyridine) ruthenium (II) (Rubipy) as a cationic fluorochrome for cytochemical and histochemical studies. After staining with Rubipy, mast cell granules (MCGs) and lymphocyte nuclei (LN) from mouse peritoneal cavity and human breast carcinoma showed intense orange fluorescence and no fading under blue or blue-violet exciting light. Staining at low pH (< 2) or pre-treatment with Al3+ ions strongly diminished the fluorescence of LN, whereas that of MCG was less affected. Ca2+ and Ba2+ ions only diminished MCG fluorescence. Blots of DNA, pectic acid, heparin, and other sulfated polysaccharides stained with Rubipy showed high emission, which was reduced in DNA and pectic acid staining at low pH. Studies with chemically modified heparins suggested that O-sulfates were more important than N-sulfates in Rubipy-heparin interactions. These results are in agreement with an ionic binding mode between Rubipy and heparin. A very suitable method for mast cell detection was found with Mayer's hematoxylin before Rubipy staining, which could be of great value for histopathological studies. This procedure allowed visualization of the mast cells by fluorescence microscopy, and nuclei and tissue morphology were easily visualized under brightfield illumination.

Fluorescence of mast cell granules in paraffin sections and cell smears induced by an N-quaternary oxazole scintillator

The N-quaternized derivative of dimethyl-POPOP (termed Q4) induces a bluish-green fluorescent reaction in mast cell granules from paraffin sections and cell smears, in addition to a previously described bluish-white fluorescent reaction in chromatin DNA. The chromatin reaction was abolished by staining the samples either with Mayer's Haematoxylin before Q4 treatment or by Q4 treatment at pH 1.5. The reaction in mast cell granules was absent after substrate methylation. The staining sequence Haematoxylin-Eosin-Q4 also worked well in paraffin sections, allowing the observation of the current histological image under bright-field illumination as well as double-colour emission under fluorescence microscopy. The sequence is proposed as a new diagnostic procedure for demonstrating mast cell granules.

p53 protein expression in viral warts from patients with epidermodysplasia verruciformis

The p53 protein is the product of a tumour suppressor gene, which is implicated in many human malignancies. p53 expression was investigated by immunohistochemistry in a series of viral warts (n = 12) from five patients with epidermodysplasia verruciformis (EV), using a monoclonal anti-p53 antibody (DO7). p53 expression was also investigated in a series of common warts (n = 8), flat warts (n = 8), and penile bowenoid papulosis (n = 6) from non-EV patients. Immunostaining was positive in 11 of 12 (92%) EV warts, whereas p53 reactivity was negative in most cases of warts from non-EV patients. Exons 5-8 of the p53 gene were screened by the polymerase chain reaction-single strand conformation polymorphism technique in four EV warts, which were strongly stained for p53, and p53 mutations were not detected. These results suggest an association between p53 accumulation (probably of wild type) and EV warts.

Anomalous expression of P-cadherin in breast carcinoma. Correlation with E-cadherin expression and pathological features

Previous studies on the cell-cell adhesion molecules P- and E-cadherin have shown that P-cadherin is not expressed in breast cancer. In contrast, the expression of E-cadherin is a normal event in these tumors, but a reduction in the levels of this molecule in neoplastic cells is associated with the histological type, high histological grade, greater tumor size, and metastasis. The expression pattern of P- and E-cadherin were immunohistochemically studied in tissue sections from normal breast tissue, benign breast lesions, and 57 infiltrating breast carcinomas. Cadherin expression was analyzed in parallel with pathological features and the immunohistochemical expression of estrogen and progesterone receptors in breast carcinomas. P-cadherin was detected in the myoepithelial cells and E-cadherin in luminal epithelial cells from normal breast and benign breast lesions. P-cadherin expression was detected in 9 of 45 cases (20%) of infiltrating ductal carcinomas of no special type; none of the special histological types that were analyzed (7 infiltrating lobular carcinomas, 3 colloid carcinomas, and 2 infiltrating papillary carcinomas) expressed P-cadherin. In infiltrating ductal carcinomas, P-cadherin expression correlated significantly with a reduction in E-cadherin expression, histological grade (all cases were grade III tumors), and hormone receptor content (8 of 9 cases were estrogen and progesterone receptor negative). Although E-cadherin was not found in the 7 infiltrating lobular carcinomas, it was present in the remaining histological types and was preserved in 15 infiltrating ductal and 3 colloid and 2 papillary carcinomas and was reduced in 30 infiltrating ductal carcinomas. In addition, a reduction in E-cadherin expression was significantly associated with high histological grade and a lack of steroid hormone receptors in infiltrating ductal carcinomas. No apparent relationship was found between P- and E-cadherin expression and tumor size and axillary lymph node metastasis. The distinct patterns of P- and E-cadherin expression observed in this study strongly suggest a differential role for these cadherins in human breast carcinogenesis.

Fluorescence of bisazo dye reaction products from the coupled tetrazonium method for proteins

The coupled tetrazonium reaction is a well known histochemical method for proteins. This method, using Fast Blue B salt and 1-naphthol, has been applied on paraffin sections of grasshopper testis and rabbit trachea, as well as on horse blood smears. Microscopic observation under bright field illumination revealed the expected purple staining of protein-rich cell and tissue structures, which also showed a strong red fluorescence under ultraviolet, violet, violet-blue and green exciting light. Some weakly stained cell components (e.g., meiotic spindles) were easily visualized by fluorescence microscopy. Control preparations lacking either the tetrazonium or naphthol treatment, and spectroscopic studies on the bisazo dye produced in vitro (showing an emission peak at 660 nm) confirmed that the red fluorescence of stained structures arises from the protein-tetrazonium-naphthol reaction product formed in situ.

Selective fluorescence of eosinophilic structures in grasshopper and mammalian testis stained with haematoxylin-eosin

After staining with Mayer's haematoxylin and eosin Y, paraffin sections of grasshopper and mouse testis were analysed by both transmitted light and fluorescence microscopy. Under violet-blue (436 nm) light excitation, a bright green emission was observed in all eosinophilic structures. Meiotic spindles (fibres and poles), mitochondrial aggregates, centriolar adjuncts in grasshopper spermatids, the basal lamina, flagellar bundles and remaining cytoplasmic droplets in the lumen of seminiferous tubules showed the most striking fluorescence induced by eosin Y. No emission was found in these structures after haemalum staining. Fluorescent microtubular components also revealed a positive immunoperoxidase reaction for alpha-tubulin. All fixation and embedding procedures (Bouin, Zenker, formaldehyde alone or followed by dichromate or glutaraldehyde, freeze-substitution) were suitable for observation by fluorescence microscopy. Acetylation, deamination, and prolonged washing of stained sections with water, salt solution or ethanol strongly reduced eosin Y fluorescence, while it slightly increased after methylation. These results show that routine haematoxylin-eosin stained tissue sections can be routinely analysed by fluorescence microscopy. The emission of eosin Y allows easy and precise recognition of eosinophilic structures, which are poorly visible under bright field illumination.

In vitro assay of erythropoietin in fetal mouse liver cultures. I. Comparison of radioactive tracers and evidence of assay specificity

In a 13 d fetal mouse liver tissue culture system for assay of erythropoietin, stimulation of incorporation of 3H-thymidine and of 125I-iodo-2'-deoxy uridine into DNA and of 59Fe iron into haem were compared as metameters of erythropoietin effect. With both DNA and haem tracers, log-dose response curves given by two preparations of human urinary erythopoietin purified to different extents (respectively 2 and 1300 IU, by bioassay in vivo, per mg of protein) were essentially identical at low dose levels although at high dose levels the less pure preparation decreased stimulation of both DNA and haem synthesis. Pre-incubation of erythropoietin with an antiserum to human erythropoietin abolished the effects of the hormones on both DNA and haem synthesis.

In vitro assay of erythropoietin in fetal mouse liver cultures. II. Effects of human transferrin bound iron and of serum on the stimulation of incorporation of 3H-thymidine into DNA

Iron bound to human transferrin but not apotransferrin, increases the effect of erythropoietin in stimulating incorporation of 3H-thymidine into DNA in fetal mouse liver cells in vitro. The effect of erythropoietin, with or without transferrin-iron is blocked by pre-incubation of the erythropoietin with rabbit anti erythropoietin serum. Human sera contain factors in addition to erythropoietin and transferin-iron which may modify the stimulation of incorporation of 3H-thymidine into fetal mouse liver DNA induced by erythropoietin. Heat treatment of sera at 56 degrees C for 30 min does not necessarily destroy these factors. Acid heat treatment of sera (pH 5.5 and 100 degrees C for 5 min) may destroy inhibitory factors and can result in an apparent increase in serum erythropoietin activity assessed in this fetal mouse liver system.

[Isolation of Ancylostoma duodenale antigens and production of immune sera]

Rabbits were immunized using intact larvae or homogenates from Ancylostoma duodenale. Antisera were tested by immunodiffusion. The homogenates promote the formation of antibodies but the intact worms were not able to induce them. The antisera were partially purified by precipitation with amonium sulphate 40% saturation and filtration through Sephadex G-200. The purified material was attached to Sepharose 6B and used as immunoabsorbent for the isolation of the antigens from the soluble extracts of parasites. The isolated antigens were used in order to obtain new antisera. These antisera were used for the preparation of more efficient immunoabsorbent which allow to isolate new antigens that gave three precipitation lines by immunodiffusion. The polyacrylamide gel electrophoresis of crude homogenate discriminate 12 components, and the electrophoresis of the isolated antigens gave only 3 bands.