The Alcian blue and combined Alcian blue--Safranin O staining of glycosaminoglycans studied in a model system and in mast cells

Placental Angiodysplasia: A New Sign for Prediction of Fetal Outcome?

The study of the placenta is of great importance, not only in the attempt to understand the etiopathogenesis of various maternal-fetal pathologies, but also in the attempt to understand whether it is possible to find the cause of pathological neonatal outcomes. On the other hand, abnormalities of blood vessel formation, such as angiodysplasias, have been poorly characterised in the literature, and there is a need for more studies investigating the potential impact on the fetus. In this paper, we retrospectively analysed 2063 placentas received at the Department of Pathology of the University of Bari 'Aldo Moro', among which we identified 70 placentas affected by angiodysplasia. On these placentas, we carried out histochemical staining with Masson's Trichrome, orcein-alcian blue, and, subsequently, immunostaining with anti-CD31, CD34, and desmin and actin muscle smoothness antibodies. Finally, we performed a morphometric analysis on the allantochorionic and truncal vessels and correlated the results with neonatal outcomes. We studied the characteristics of the angiodysplasias in detail, dividing the patients into two classes (A and B) according to the morphology and histochemical characteristics of the affected vessels; statistical analysis reported a statistically significant association (p < 0.05) between the ratio of maximum thickness to maximum diameter (Tmax/Dmax) and neonatal outcome, with only 30% physiological outcome in the cohort of the placentas affected by angiodysplasia. These results shed light on a rather neglected aspect in the 2015 Amsterdam Classification, as well as in the literature, and provided strong evidence that placental angiodysplasia is predictive of an increased likelihood of the pathological fetal outcome, while other factors remain in the field. Studies with larger case series and guidelines with more attention to these aspects are mandated to further investigate the predictive potential of this pathology.

Electrical Stimulation in Cartilage Tissue Engineering

Electrical stimulation (ES) has been frequently used in different biomedical applications both in vitro and in vivo. Numerous studies have demonstrated positive effects of ES on cellular functions, including metabolism, proliferation, and differentiation. The application of ES to cartilage tissue for increasing extracellular matrix formation is of interest, as cartilage is not able to restore its lesions owing to its avascular nature and lack of cells. Various ES approaches have been used to stimulate chondrogenic differentiation in chondrocytes and stem cells; however, there is a huge gap in systematizing ES protocols used for chondrogenic differentiation of cells. This review focuses on the application of ES for chondrocyte and mesenchymal stem cell chondrogenesis for cartilage tissue regeneration. The effects of different types of ES on cellular functions and chondrogenic differentiation are reviewed, systematically providing ES protocols and their advantageous effects. Moreover, cartilage 3D modeling using cells in scaffolds/hydrogels under ES are observed, and recommendations on reporting about the use of ES in different studies are provided to ensure adequate consolidation of knowledge in the area of ES. This review brings novel insights into the further application of ES in in vitro studies, which are promising for further cartilage repair techniques.

Number and Distribution of Mast Cells in Reproductive Systems of Gravid and Non-Gravid Female Mice

Mast cells are mainly distributed in tissues exposed to the external environment, but they are also found in ovaries, oviducts and uterus. We determined the difference in the number and distribution of Alcian Blue (+) and Safranine O (+) mast cells in reproductive systems of gravid and non-gravid female mice by histological examination. We showed that the number of mast cells is significantly higher in the reproductive system of gravid mice than in the reproductive system of non-gravid mice. Mast cells are unevenly distributed in ovaries, oviducts and uterus in both gravid and non-gravid mice. A large number of mast cells reside close to blood vessels throughout the entire reproductive system.

Recombinant Live Attenuated Influenza Vaccine Viruses Carrying Conserved T-cell Epitopes of Human Adenoviruses Induce Functional Cytotoxic T-Cell Responses and Protect Mice against Both Infections

Human adenoviruses (AdVs) are one of the most common causes of acute respiratory viral infections worldwide. Multiple AdV serotypes with low cross-reactivity circulate in the human population, making the development of an effective vaccine very challenging. In the current study, we designed a cross-reactive AdV vaccine based on the T-cell epitopes conserved among various AdV serotypes, which were inserted into the genome of a licensed cold-adapted live attenuated influenza vaccine (LAIV) backbone. We rescued two recombinant LAIV-AdV vaccines by inserting the selected AdV T-cell epitopes into the open reading frame of full-length NA and truncated the NS1 proteins of the H7N9 LAIV virus. We then tested the bivalent vaccines for their efficacy against influenza and human AdV5 in a mouse model. The vaccine viruses were attenuated in C57BL/6J mice and induced a strong influenza-specific antibody and cell-mediated immunity, fully protecting the mice against virulent influenza virus infection. The CD8 T-cell responses induced by both LAIV-AdV candidates were functional and efficiently killed the target cells loaded either with influenza NP366 or AdV DBP418 peptides. In addition, high levels of recall memory T cells targeted to an immunodominant H2b-restricted CD8 T-cell epitope were detected in the immunized mice after the AdV5 challenge, and the magnitude of these responses correlated with the level of protection against pulmonary pathology caused by the AdV5 infection. Our findings suggest that the developed recombinant vaccines can be used for combined protection against influenza and human adenoviruses and warrant further evaluation on humanized animal models and subsequent human trials.

Expressions of vascular endothelial growth factor receptors, Flk1 and Flt1, in rat skin mast cells during development

Vascular endothelial growth factor-A (VEGF-A) is a principal regulator of hematopoiesis as well as angiogenesis. However, the functions of VEGF-A and its receptors (VEGFRs) in the differentiation of mast cells (MCs) in the skin remain unclear. The aim of this study was to determine the expression patterns of two VEGFRs (Flk1 and Flt1) in the skin MCs during development and maturation in rats. From the 17th days of embryonic development (E17) to 1 day after birth (Day 1), most of skin MCs were immature cells containing predominant alcian blue (AB)⁺ rather than safranin O (SO)⁺ granules (AB>SO MCs). AB>SO MC proportions gradually decreased, while mature AB<SO MC proportions increased from Day 7 to 28. Flk1⁺ MC proportions increased from E20 and reached to approximately 90% from Day 1 to 21, thereafter decreased to about 10% at Day 60 and 90. Flk1⁺ MC proportions changed almost in parallel with the numbers of MCs and Ki67⁺ MC proportions from E17 to Day 90. The proportions of MCs with both nuclear and cytoplasmic Flt1-immunoreactivity were markedly increased at Day 28, when the proportions of nuclear Flk1⁺, Ki67⁺, and AB>SO MCs had significantly decreased, and AB<SO MC proportions significantly increased. Considering that the main function of Flt1 is suppression of Flk1 effects, our results indicated that cross-talk between Flk1 and Flt1 regulates the proliferation and maturation of the skin MCs during late embryonic and neonatal development in rats.

Alizarin Red and Alcian Blue Preparations to Visualize the Skeleton

Understanding proteolytic remodeling of extracellular matrix involves the generation of global or conditional knockout mice by homologous recombination in embryonic stem cells or their manipulation through new advanced technologies such as CRISPR-Cas9. These models provide opportunities to understand the roles of ADAMTS genes in skeletogenesis. Whole-mount skeletal preparations are necessary for assessment of the skeletal phenotype. They allow for facile visualization of skeletal patterning, size and shape of skeletal elements, and skeletal structure. This protocol describes the staining of the murine skeleton using Alcian blue to identify cartilage and alizarin red to identify bone.

Evidence for the role of extrusomes in evading attack by the host immune system in a scuticociliate parasite

Like other ciliates, Philasterides dicentrarchi, the scuticociliate parasite of turbot, produces a feeding-only or growing stage called a trophont during its life cycle. Exposure of the trophonts to heat-inactivated serum extracted from the turbot host and containing specific antibodies that induce agglutination/immobilization leads to the production of a mucoid capsule from which the trophonts later emerge. We investigated how these capsules are generated, observing that the mechanism was associated with the process of exocytosis involved in the release of a matrix material from the extrusomes. The extruded material contains mucin-like glycoproteins that were deposited on the surface of the cell and whose expression increased with time of exposure to the heat-inactivated immune serum, at both protein expression and gene expression levels. Stimulation of the trophonts with the immune serum also caused an increase in discharge of the intracellular storage compartments of calcium necessary for the exocytosis processes in the extrusomes. The results obtained suggest that P. dicentrarchi uses the extrusion mechanism to generate a physical barrier protecting the ciliate from attack by soluble factors of the host immune system. Data on the proteins involved and the potential development of molecules that interfere with this exocytic process could contribute to improving the prevention and control of scuticociliatosis in turbot.

Visualization of a hyaluronan network on the surface of silicone-hydrogel materials

Biotrue multipurpose solution (MPS) is a bioinspired disinfecting and conditioning solution that includes hyaluronic acid (HA) as a natural wetting agent. Previous studies demonstrated that HA sorbed from Biotrue MPS on both conventional and silicone hydrogel (SiHy) contact lens materials; an in vitro simulated-wear test validated the presence of HA on the lens surfaces for as long as 20 hours. In this study, the morphology and distribution of HA sorbed from both Biotrue and pure HA solution on SiHy contact lens surfaces was examined. Atomic force microscopy imaging was used to illustrate the topography of fresh SiHy contact lens materials before and after incubation with 0.1% (w/v) HA solution. The distribution, as well as fine details of the HA network, were resolved by first staining HA with Gram's safranin, then imaging with confocal laser-scanning microscopy and differential interference-contrast microscopy. In this approach, SiHy materials take up the dye (safranin) nonspecifically, such that the resultant safranin-HA complex appears dim against the fluorescent lens background. Balafilcon A was chosen as the representative of glassy SiHy lenses that require postpolymerization plasma treatment to increase wettability. Senofilcon A and samfilcon A were chosen as representatives of SiHy materials fabricated with an internal wetting agent. A confluent and dim HA-safranin network was observed adhered to balafilcon A, senofilcon A, and samfilcon A lens surfaces incubated with either 0.1% (w/v) HA solution or Biotrue MPS. Therefore, the conditioning function provided by Biotrue MPS may be in part explained by the presence of the HA humectant layer that readily sorbs on the various types of SiHy contact lens materials.

Improving the soluble expression and purification of recombinant human stem cell factor (SCF) in endotoxin-free Escherichia coli by disulfide shuffling with persulfide

We here present a new method for the expression and purification of recombinant human stem cell factor (rhSCF(164)) in endotoxin-free ClearColi(®) BL21(DE3) cells harboring codon-optimized Profinity eXact™-tagged hSCF cDNA. Previously, we demonstrated that co-expression with thioredoxin increased the solubility of rhSCF in Escherichia coli BL21(DE3), and addition of l-arginine enhanced chromatography performance by removing the endotoxin-masked surface of rhSCF. Initially, we tried to express rhSCF in an endotoxin-free strain using a thioredoxin co-expression system, which resulted in significantly lower expression, possibly due to the stress imposed by overexpressed thioredoxin or antibiotics susceptibility. Therefore, we developed a new expression system without thioredoxin. External redox coupling was tested using persulfides such as glutathione persulfide or cysteine persulfide for the in vivo-folding of hSCF in the cytoplasm. Persulfides improved the protein solubility by accelerating disulfide-exchange reactions for incorrectdisulfides during folding in E. coli. Furthermore, the persulfides enhanced the expression level, likely due to upregulation of the enzymatic activity of T7 RNA polymerase. The recombinant protein was purified via affinity chromatography followed by cleavage with sodium fluoride, resulting in complete proteolytic removal of the N-terminal tag. The endotoxin-free fusion protein from ClearColi(®) BL21(DE3) could bind to the resin in the standard protocol using sodium phosphate (pH 7.2). Furthermore, purified rhSCF enhanced the proliferation and maturation of the human mast cell line LAD2. Thus, we conclude that use of the protein expression system employing E. coli by disulfide shuffling with persulfide addition could be a very useful method for efficient protein production.

Expression of bioactive soluble human stem cell factor (SCF) from recombinant Escherichia coli by coproduction of thioredoxin and efficient purification using arginine in affinity chromatography

Stem cell factor (SCF) known as the c-kit ligand is a two disulfide bridge-containing cytokine in the regulation of the development and function of hematopoietic cell lineages and other cells such as mast cells, germ cells, and melanocytes. The secreted soluble form of SCF exists as noncovalently associated homodimer and exerts its activity by signaling through the c-Kit receptor. In this report, we present the high level expression of a soluble recombinant human SCF (rhSCF) in Escherichia coli. A codon-optimized Profinity eXact™-tagged hSCF cDNA was cloned into pET3b vector, and transformed into E. coli BL21(DE3) harboring a bacterial thioredoxin coexpression vector. The recombinant protein was purified via an affinity chromatography processed by cleavage with sodium fluoride, resulting in the complete proteolytic removal the N-terminal tag. Although almost none of the soluble fusion protein bound to the resin in standard protocol using 0.1M sodium phosphate buffer (pH 7.2), the use of binding buffer containing 0.5M l-arginine for protein stabilization dramatically enhanced binding to resin and recovery of the protein beyond expectation. Also pretreatment by Triton X-114 for removing endotoxin was effective for affinity chromatography. In chromatography performance, l-arginine was more effective than Triton X-114 treatment. Following Mono Q anion exchange chromatography, the target protein was isolated in high purity. The rhSCF protein specifically enhanced the viability of human myeloid leukemia cell line TF-1 and the proliferation and maturation of human mast cell line LAD2 cell. This novel protocol for the production of rhSCF is a simple, suitable, and efficient method.

Capsular contracture after breast reconstruction: collagen fiber orientation and organization

BACKGROUND

Breast implant capsular contracture is a common complication of implant-based breast reconstruction. To develop nonsurgical interventions to combat breast capsular contractures, a clearer understanding of the process is required. Comparing breast implant-related capsular contracture to the fibrotic scarring process, the hypothesis is that these processes differ with regard to the compaction of collagen fibers within the connective tissue matrix.

METHODS

Morphologic differences in the connective tissue matrix by light, polarized light, and fluorescence microscopy documents these differences. Discarded Baker grade II and III periimplant capsules harvested during routine breast reconstructive operations were used for the evaluation.

RESULTS

Within severe breast capsule contractures, light microscopy revealed the absence of mast cells, whereas polarized light microcopy showed that collagen fiber bundles were consolidated into thick cable-like structures. In less severe breast capsules, mast cells were present, whereas thick cable-like collagen structures were absent. By fluorescence microscopy, fibroblast populations associated with severe contractures were oriented perpendicular to the long axis, suggesting a spiral orientation in the compaction of these cable-like structures. These findings were absent in less severe contractures.

CONCLUSIONS

To the authors' knowledge, these histologic findings in breast implant capsules are unreported and unique when compared with other fibrotic contractures. Elucidating the biological mechanisms involved in the reorganization of collagen fiber bundles that lead to implant-related capsular contracture is a critical step for developing strategies to treat and control breast capsule contractures.

Generation of mast cells from mouse fetus: analysis of differentiation and functionality, and transcriptome profiling using next generation sequencer

While gene knockout technology can reveal the roles of proteins in cellular functions, including in mast cells, fetal death due to gene manipulation frequently interrupts experimental analysis. We generated mast cells from mouse fetal liver (FLMC), and compared the fundamental functions of FLMC with those of bone marrow-derived mouse mast cells (BMMC). Under electron microscopy, numerous small and electron-dense granules were observed in FLMC. In FLMC, the expression levels of a subunit of the FcεRI receptor and degranulation by IgE cross-linking were comparable with BMMC. By flow cytometry we observed surface expression of c-Kit prior to that of FcεRI on FLMC, although on BMMC the expression of c-Kit came after FcεRI. The surface expression levels of Sca-1 and c-Kit, a marker of putative mast cell precursors, were slightly different between bone marrow cells and fetal liver cells, suggesting that differentiation stage or cell type are not necessarily equivalent between both lineages. Moreover, this indicates that phenotypically similar mast cells may not have undergone an identical process of differentiation. By comprehensive analysis using the next generation sequencer, the same frequency of gene expression was observed for 98.6% of all transcripts in both cell types. These results indicate that FLMC could represent a new and useful tool for exploring mast cell differentiation, and may help to elucidate the roles of individual proteins in the function of mast cells where gene manipulation can induce embryonic lethality in the mid to late stages of pregnancy.

Pathways of murine mast cell development and trafficking: tracking the roots and routes of the mast cell

The appreciation of the role of the mast cell (MC) in inflammatory processes has expanded dramatically during the last decade. Many of these processes, especially more prolonged responses, are accompanied by an increase in the number of MCs, and much of this increase is likely because of recruitment of immature progenitors with subsequent maturation under the control of the tissue microenvironment. We have begun to identify many of the cell-surface molecules that control this influx and have traced the development of these cells back to their hematopoietic roots. This development proceeds along the myelomonocytic pathway with distinct intermediates having been identified in both bone marrow and spleen. The expression of alpha4beta7 integrins has played a prominent role in this process, as it helped identify a bipotent basophil MC precursor in the spleens of C57BL/6 mice. This integrin also controls basal influx into the intestine and, along with alpha4beta1 integrins, plays a critical role in recruitment to inflamed lungs. Investigation of chemokines and chemokine receptors in these processes led to the identification of a dual role for the murine interleukin-8 receptor CXCR2. This alpha-chemokine receptor affects MC progenitor trafficking by its expression by MC progenitors and by its expression on stromal cells, likely endothelium, affecting trafficking to both intestine under basal conditions and lung during inflammatory recruitment.

Mast Cells in the Salivary Glands and Tongue of the Ferret: Demonstration and Some Histochemical Observations

Previous investigations failed to demonstrate mast cells in the alimentary tract and extraparietal glands of the ferret. It was decided therefore to test this and assess factors that may be of influence. Major salivary glands and tongues of mature ferrets, which had been fixed in formalin-calcium, were examined by means of light microscopical histochemistry. Staining of paraffin sections with techniques depending on basic dyes or esterolytic activity was carried out for conventional times with and without previous oxidation, hot acid hydrolysis, and trypsin and beta-glucuronidase digestion. Aldehyde fuchsin and high iron diamine consistently revealed the presence of few mast cells in interstitial stroma of salivary glands and lingual musculature, and in the lamina propria of lingual mucosa. Alcian blue at 0.5 M MgCl2 and safranin produced less consistent results, and even fewer metachromatic mast cells were detected. No staining of mast cells was obtained with the technique for naphthol AS-D chloroacetate esterase. Pretreatment did not increase the numbers and/or staining reactions of mast cells. The results refute the previous misconception and suggest that ferret is a species with a low incidence of mast cells largely expressing a connective-tissue phenotype.

Histochemical studies of the extracellular matrix of human articular cartilage--a review

OBJECTIVE

This paper reviews the histochemistry of the extracellular matrix of human articular cartilage. No systematic review of histochemical knowledge and techniques in the study of articular cartilage has been published previously.

METHODS AND RESULTS

Literature was searched in the Winspirs Medline database from 1960 to 2000. Only techniques applicable for bright field or polarization microscopy were considered. Unless otherwise noted, all applies to hyaline cartilage. The most widely used fixatives are adequate for routine staining of proteins, but proteoglycan fixation is problematic, and no one fixative can be recommended. Proteoglycan can be stained reliably but it is problematic that, at low substrate concentrations, these methods are not stoichiometric. Collagen can be stained efficiently, although attempts to differentiate collagen types have not been successful.

CONCLUSIONS

Detailed studies of fixation and staining procedures should be carried out and standards for cartilage sampling, handling and evaluation agreed upon if results from different laboratories are to be compared.

Immature peritoneal mast cells in neonatal rats express the CTMC phenotype, as well as functional IgE receptors

The purpose of this study was to investigate the relationship between the differentiation and maturation of mast cells and the expression of IgE receptors on their surface in neonatal animals in vivo. Another aim was to clarify whether connective tissue mast cells (CTMC) undergo a maturation process involving a transdifferentiation from mucosal mast cells (MMC) during this period of time. Mast-cell phenotypes were studied in terms of the profiles of proteinases and proteoglycan. In 1-week-old rats, the mast-cell granules stained with Alcian blue rather than with safranin (AB+/S-) in the Alcian blue/safranin staining sequence, normally regarded as a property of MMC. However, the AB+/S-stained proteoglycan was degradable by nitrous acid and stained with berberine sulphate, thus indicating that it contained heparin rather than chondroitin sulphate. The mast cells expressed rat mast-cell proteinase (RMCP) I rather than RMCP II, which is normally found in MMC. The mast cells of 1-week-old rats expressed functional IgE receptors, by showing a dose-dependent IgE-mediated histamine release of mast cells. About 70% of the IgE receptors on the mast cells were occupied by IgE. In 2- to 3-week-old rats, there was a progressive increase in mast cells stained with both Alcian blue and safranin or with safranin alone, i.e. they gradually changed towards the staining properties of CTMC (AB-/S+). The expression and the degree of IgE occupancy of the receptors increased in 1- to 3-week-old animals. This was paralleled by an increment in cell size and in the content of heparin, histamine and serotonin in the mast cells. The findings thus indicate that the peritoneal mast cells of neonatal rats express the CTMC phenotype and undergo a maturation process at from 1 to 3 weeks of age, without involving a transdifferentiation from MMC. The maturation of the mast cells is accompanied by an increase in the expression of functional IgE receptors on the cell surface. production was detectable as early as in 1-week-old rats.

Potential use of embalmed cadavers to study mast cell presence

BACKGROUND

Embalmed cadavers in medical classes represent a potential source for collecting human tissues without the inherent problems of obtaining fresh or surgical specimens. Although the manner of fixation and vagaries of embalming techniques eliminate many such tissues for histological assessment, other techniques can be applied successfully to embalmed tissues. Pertinent to the present study, mast cells contain granules that are preserved under good fixation in formaldehyde, a main ingredient in embalming fluids. Visualization of these granules is possible, even though the ultrastructure of these cells is not preserved.

METHODS

Two techniques for the visualization of connective tissue mast cells were compared using embalmed and fresh specimens: Alcian blue and avidin conjugated to fluorescein isothiocyanate (FITC-Avidin). Both will bind to mast cell granules, even in the presence of formaldehyde.

RESULTS

Although mast cell numbers in the connective tissue did not differ between embalmed and fresh tissues, comparisons between the techniques involved showed the FITC-Avidin technique to be possibly more sensitive, perhaps because of the increased contrast from the fluorescent dye.

CONCLUSIONS

Thus for some studies, human cadavers may provide a valuable source of tissue. However, use of embalmed tissue necessitates ensuring good embalming, checking for dehydration, and proper storage until embedment.

Histochemical heterogeneity of dermal mast cells in athymic and normal rats

Mucosal mast cells (MMC) and connective tissue mast cells (CTMC) of the rat contain different proteoglycans, which can be distinguished using histochemical methods. The chondroitin sulphate proteoglycan of the MMC, unlike the heparin of the CTMC, does not show fluorescent berberine binding, is susceptible to aldehyde fixatives and stains preferentially with Alcian Blue in a staining sequence with Safranin. The majority of the dermal mast cells are typical CTMC and are located in the deep part of the dermis. Subepidermal mast cells are comparatively few in normal rats but numerous in athymic rats and mice. These cells differ from other dermal mast cells in that they stain preferentially with Alcian Blue and they appear to contain little histamine. We examined some of the histochemical properties of the skin mast cells of female PVG-rnu/rnu rats and their heterozygous littermates aged from 5 to 29 weeks. The thiazine dye-binding of the subepidermal mast cells was partially blocked by formaldehyde fixation and only about half of them showed a weakly fluorescent berberine binding. The critical electrolyte concentration of the Alcian Blue staining of the subepidermal mast cells was between that of CTMC and MMC. Deaminative cleavage with nitrous acid abolished the staining of all skin mast cells, while that of the MMC was unaffected. There were no statistically significant differences in the staining patterns of the dermal mast cells between different ages or groups of rat. These results indicate that the subepidermal mast cells contain a heparin proteoglycan which is, however, different from that of the typical CTMC of other sites. They thus appear to represent a second example of a mast cell within a defined anatomical location exhibiting a distinct proteoglycan expression.

Extracellular mammalian polysaccharides: glycosaminoglycans and proteoglycans

This review of the mammalian extracellular matrix polysaccharides covered the glycosaminoglycans (GAGs) and their association into proteoglycans. As they necessarily pertain to the chromatographic and electrophoretic separations of these molecules, the structural features of the five principal GAGs were briefly reviewed. Much of the current structural work as well as the separation technology has been concerned with the sulfation state and copolymeric sequences of the individual classes of GAGs. The separation methods discussed included electrophoresis by agarose, acrylamide and cellulose acetate, high-performance liquid chromatography (HPLC), ion-exchange, gel permeation and biospecific affinity methods. Since detection systems are an integral part of chemical separation technology, current thoughts about the best methods to assay GAGs or detect column fractions were discussed. These included polysaccharide-specific detection systems such as Alcian blue dye, 1,9-dimethylmethylene blue, bovine serum albumin-Coomassie blue, as well as non-specific carbohydrate detection systems such as the carbazole or indole hydrochloride methods. Instrumentation used in the detection of chromatography fractions for these molecules was discussed, since the usual ultraviolet detector, standard with HPLC equipment, is often unsatisfactory. The most sensitive specific detection method for GAGs is the use of monoclonal antibodies, which are only now becoming commercially available. The use of these antibodies, combined with HPLC separation, appears to be the best available biochemical technology for studying the extracellular matrix polysaccharides. Finally, the association between proteoglycans, GAGs and mammalian disease processes was reviewed, emphasizing mucopolysaccharidoses and arthritis. The early detection of both of these diseases is desired for effective counselling and treatment. Many of the methods discussed here have been applied, but others are yet to be tried in efforts to further that goal.

Matrix models. Essential tools for microscopic cytochemical research

An overview is given of the preparation and use of model systems for cytochemistry, dealing with quantitative as well as qualitative aspects. Descriptions are given of the various possibilities to prepare cytochemical matrix models, ranging from macroscopic and microscopic films, to models with more cell-like dimensions as agarose beads, artificial cells and erythrocyte ghosts. Such models allow the study of a large variety of cytochemical processes. Their potentialities are demonstrated in a number of specific applications, comprising: the study of the influence of fixation on cellular processes, reaction specificity and reaction kinetics, quality of reagents and biochemical calibration in cytochemical staining; factors influencing localization of the specific endproduct in enzyme cytochemistry; immunocytochemistry and hybridocytochemistry.

Histochemical staining of cadmium thiolate clusters in livers of rats treated chronically with cadmium

In livers of rats exposed to varying doses of CdCl2 80-90% of the cadmium content present in the fresh tissue is retained if these livers are fixed with a neutral or acid formalin fixative. Cadmium assays during different stages of the staining procedure for protein bound disulphides show the ability of this staining to demonstrate cadmium thiolate clusters next to disulphides. The methods described may also be useful in gaining more insight in the mechanism involved in fixation and staining procedure of some other metals.

Cuprolinic Blue: a specific dye for single-stranded RNA in the presence of magnesium chloride. I. Fundamental aspects

Qualitative and quantitative aspects of the cationic dye Cuprolinic Blue were investigated with model films of polyacrylamide gel in which RNA, DNA and other biological polyanionic compounds had been incorporated. In the presence of 1 M MgCl2, Curpolinic Blue was found to bind specifically to single-stranded RNA, leaving native DNA, proteins, (acid) polysaccharides and phospholipids completely unstained. Under these conditions, Cuprolinic Blue is complexed by non-electrostatic bonds with non-stacke purine bases, mainly adenine. Optimal conditions for dye binding and differentiation have been defined. Both the Cuprolinic Blue-MgCl2 staining of single-stranded RNA and the Cuprolinic Blue staining of RNA and DNA in the absence of MgCl2 were found to obey the Lambert-Beer law. The advantages and possible applications of Cuprolinic Blue are compared with well-known (indirect) histochemical RNA staining procedures.

Changes in uterine mast cells during the estrous cycle in the Syrian hamster

Adult virgin female Syrian hamsters were killed at known stages of the estrous cycle, and mast cells were counted in the myometrium, endometrium, and mesometrial-triangle region of the uterus and in the pinna. Tissues were fixed in Helly's solution, and mast cells were stained using 0.06% toluidine blue in 0.12 M Michaelis' veronal acetate-hydrochloric acid buffer, pH 4.5. The number of mast cells in the myometrium and endometrium was found to vary with the estrous cycle, whereas the number in the mesometrial-triangle region and the pinna showed no such variation. The number of mast cells in the myometrium and endometrium was lowest on day 4 of the cycle (the day before the night during which ovulation would occur) and increased approximately twofold to maximal levels found on days 1 and 2. Intermediate levels were seen on day 3. The origin of the increase in mast cell numbers from day 4 to day 1 was investigated using a combined alcian blue--safranin stain to differentiate between immature and mature mast-cell granules. The results obtained did not support the hypothesis that the increase was due to de novo differentiation of mast cells from precursors, but, equally, no evidence was obtained to refute this hypothesis.

Fixation and staining of granules in mucosal mast cells and intraepithelial lymphocytes in the rat jejunum, with special reference to the relationship between the acid glycosaminoglycans in the two cell types

Various fixation and staining procedures have been examined in order to obtain optimal numbers and acceptable morphology of the mucosal mast cells and granular intraepithelial cells in the rat jejunum. For subsequent staining with Alcian Blue, the best fixation of the jejunum was obtained with a methanol-formaldehyde-acetic acid mixture. Specific staining of the granules of these cells has been obtained using Alcian Blue at pH 5.8, at which hydrogen ion concentration more cells stain than in the usual very acid conditions. Specificity is achieved by the use of magnesium chloride concentrations above the critical electrolyte concentrations for staining of protein and nucleic acid by Alcian Blue, and by the use of Safranin O as a competitive counterstain. The critical electrolyte concentration technique has also been applied to a comparative study of the glycosaminoglycan in the two cell types. Evidence is presented that the glycosaminoglycan in the granular intraepithelial cell has either a lower degree of sulphation or a lower molecular weight or both than the material in mucosal mast cells. This finding may support the possibility that the granular intraepithelial lymphocyte is a precursor of the mucosal mast cell.

Effects of strong electrolytes on the iron alum--Alcian Blue--Safranin staining of mast cell granules of the rat

Rat mast cells fixed in Carnoy's fluid were stained with iron alum-Alcian Blue--Safranin solution after pre-treatment with strong electrolyte solutions including acids, neutral salts and alkalis. Although both red and blue mast cells were observed without pre-treatment, most mast cells were stained blue and a few red when they were stained after the pre-treatment. Mast cell granules contain salt complexes formed between basic proteins and acidic polysaccharides through ionic linkages between protein basic groups and polysaccharide sulphate and carboxylic acid groups. It is suggested that when sections are treated with strong electrolyte solutions, complexes are broken by disruption of ionic linkages and sulphate and carboxylic acid groups of polysaccharides masked by basic proteins become available for binding Alcian Blue. This was confirmed by model experiments performed with smears of a heparin-lysozyme complex. When mast cells were fixed in aldehyde-containing fixatives, no effects of strong electrolyte solutions on the staining properties of mast cell granules were revealed.

Protein content, dry mass and chemical composition of individual mast cells related to body growth

Recently developed quantitative microscopical techniques were used to study relations between body growth and protein content as well as dry mass of individual mast cells. Since previous studies had shown an age-related increase of mast cell content of 5-hydroxytryptamine (5-HT) and heparin, these mast cell components were also included in the present study. The cells were obtained from the peritoneal cavity of rats aged 44--269 days (body weights 189--610 g). All studied mast cell parameters showed an increase that was related to the growth of the animals. The dry mass increased 60%, protein 50%, heparin 50% but 5-HT increased as much as 260% during the studied growth period. There was a mutual and linear correlation between all studied mast cell parameters. Population studies, based on large scale measurements of individual mast cells from young and adult rats, were made. These studies showed that histograms of 5-HT content, protein content and dry mass of individual mast cells were skewed with a tail towards higher values and approximately lognormal. On the other hand, the frequency distribution of heparin content of individual mast cells was approximately normal.

Polyacrylamide films as a tool for investigating qualitative and quanitative aspects of the staining of glycosaminoglycans with basic dyes

With the introduction of model films of polyacrylamide gel into which purified glycosaminogly cans (GAGs) have been 'incorporated', the direct recording of metachromatic spectra with virtually no interference of the corresponding orthochromatic peaks has become possible. Because this model system yields situations comparable to those of stained sections under the microscope, it is well suited for investigating qualitative and quantitative aspects of histochemical staining procedures. Previous model experiments have shown that under aqueous conditions only minor differences can be observed between the metachromatic peaks of different GAGs complexed with a suitable dye (e.g. Toluidine Blue O, Thionin, Safranin O, Cresyl Violet, Cystal Violet). In non-aqueous media, such as glycerol and ethylene glycol, the complexes with Toluidine Blue O revealed a special pattern for heparin, having a metachromatic peak (517 nm) about 30 nm lower than that of all other GAGs. This observation has formed the basis of a method for the qualitative microspectrophotometric detection of heparin in situ which was worked out by combining model film experiments with microspectrophotometric data obtained from rat mast cells. Since only a limited number of cells in necessary for obtaining reliable data with this method, the presence of heparin in the cytoplasmic granules of normal human mast cells and basophilic granulocytes could thus be proved directly. Alcian Blue 8GX, another basic dye frequently use in GAG histochemistry, has also been investigated with polyacrylamide films. In contrast to the metachromatic dyes, the rate of staining with Alcian Blue depends to a large extent on the rate of penetration of the dye into the model films. The rate of penetration is also a phenomenon of great importance for dye binding in situ, where complex basic protein molecules may form a barrier for the Alcian Blue molecules. The model film studies performed so far have yielded conditions that provide maximal staining (up to an optimal level) and a linear relationship betweeen the concentration of GAG and the AB binding. The presence of basic protein, electrostatically bound to the GAG, was not found to influence either the rate of staining or the maximal amount of dye binding.