Detection of membrane and intracellular antigens by flow cytometry following ORTHO PermeaFix fixation

In the present study, we explored the suitability of a new cell fixative (ORTHO PermeaFix, OPF) for the detection by flow cytometry of intracellular molecules while preserving the cell surface immunoreactivity, scatter features and morphology. The effect of OPF was investigated on whole blood of ten normal donors, and on separated blasts of 17 leukemic patients. OPF fixation for 45 min to 24 h maintained the morphology of lymphoid cells with minimal cellular distortion and scatter changes, and only slightly modified cell surface immunoreactivity. For at least 1 week following fixation, the cells were still suitable for immunostaining with monoclonal antibodies that recognize the main lymphoid populations. These included CD3, CD4 and CD8 for T-cell subsets, CD19 and CD16 for B lymphocytes and NK cells, and CD45 for leukocyte common antigen (LCA). The OPF fixation of leukemic cells allowed the simultaneous detection of nuclear TdT in conjunction with membrane CD19, and with membrane and/or cytoplasmic CD22 in common-ALL, as well as with cytoplasmic CD3 in T-ALL cases. Our findings suggest that with the introduction of this new fixative into the routine laboratory service, a number of convenient and practical arrangements can be made which increase the efficiency of immunodiagnosis. Small laboratories with no inhouse flow-cytometric facilities can now accumulate OPF-treated whole blood samples for at least 3-4 days and send these to reference laboratories. In addition, the immunodiagnosis of acute leukemia is greatly facilitated by combination staining for membrane and intracellular antigens both at diagnosis and when the analysis of minority populations is warranted for detecting minimal disease.

Practical aspects of fixatives in high resolution nuclear image analysis

Three different methods of fixation (ethanol/Carbowax, formaldehyde, and Carnoy) and four different protocols (without Böhm post-fixation on an uncoated slide, and with Böhm post-fixation on Poly-L-Lysine coated slide, an uncoated slide and a previously Papanicolaou stained slide) were evaluated for their application in high resolution image analysis of Feulgen stained nuclei. The aim of the study was to find a combination with the best reproducibility and the least variance under normal laboratory conditions. Care was taken not to exclude any "normal" laboratory variability. The combinations were evaluated for densitometric, geometric, as well as texture features. Selected features were determined on a CAS-100 using the Cell Measurement Program (Cell Analysis Systems, Inc. Lombard, IL). Diploid and tetraploid rat liver nuclei were used. Ethanol/Carbowax fixation-with Böhm post-fixation proved most stable. This fixation method also gave feature values for previously Papanicolaou stained slides that were comparable to direct Feulgen stained nuclei. Acceptable results were achieved with all three fixatives and the various combinations if one adhered strictly to protocol. In routine practice this usually does not happen. Therefore Ethanol/Carbowax fixation with Böhm post-fixation was considered most suited for routine determination of feature values on the CAS-100.

Vascular contractile potency of endothelin-1 is increased in the presence of monocytes or macrophages

Accumulation of inflammatory cells and altered responsiveness to vasoactive mediators are commonly observed events in atherosclerotic vessels. We studied the effect of monocytic cells on endothelin-1 (ET-1)-induced contraction of strips of guinea pig carotid artery. The vascular contractile potency of ET-1 was increased markedly in the presence of human peripheral blood monocytes, guinea pig alveolar macrophages (M phi), and the human monocytic cell line, THP-1. Specific binding of 125I-labeled ET-1 to these cells was detected, and Scatchard analysis indicated a dissociation constant value of approximately 1 nM. In contrast, the human monocytic cell line, U-937, failed to bind 125I-ET-1 and did not alter ET-1 potency, suggesting that the ability of monocytic cells to increase ET-1 potency requires expression of ET receptors. Selective inhibition of ET-1 binding to vascular smooth muscle with BQ-123, an ETA receptor antagonist that does not inhibit ET-1 binding to monocytes, resulted in complete inhibition of vascular contraction. These data indicate that ET-1-induced vasoconstriction may be increased by monocytic cells via stimulation of monocyte endothelin receptors.

Non-aqueous fixative preserves macromolecules on the endothelial cell surface: an in situ study

A fixative composed of 1% w/v osmium tetroxide dissolved in a tluorocarbon (FC-72) was used to perfusion-fix rat blood vessels for this ultrastructural study. With non-aqueous fixation, the lumenal surfaces of endothelial cells in cardiac and skeletal muscles retained an extracellular coat which was morphologically consistent with glycocalyx. Venules displayed the greatest density and depth (up to 870 nm thick) of glycocalyx, but all vessel types had at least 70 nm of surface coat. The results indicate that non-aqueous fixatives will be useful in studies of the endothelial cell lumenal surface, while offering excellent preservation of general ultrastructure.

Alteration of hydroxylapatite coatings exposed to chemicals used in histological fixation

Histological evaluation of retrieved devices allows for assessment of the biological response to the implants. Interaction between the biomaterial and the fluids used in the processing may alter the appearance or composition of the device. This may result in artifacts due to processing which are misinterpreted as being caused by the biological response. Alteration by the fluids used in fixation may be particularly important with materials that have a propensity to interact with aqueous environments, as in the case of calcium phosphate ceramics. Therefore, we examined the effects of various standard histological fixation techniques on hydroxylapatite coated metal implants. Of the techniques examined, fixation with ethanol appeared to affect the surface morphology the least, whereas fixation in unbuffered formalin appeared to affect the bulk composition of these samples the least. Fixation in buffered formalin resulted in marked changes in both surface morphology and bulk composition.

Immunohistochemical demonstration of c-erbB-2 oncoprotein in gastric adenocarcinoma: comparison of cryostat and paraffin wax sections and effect of fixation

AIMS

To investigate the effects of fixation on the immunohistochemical demonstration of c-erbB-2 oncoprotein using paraffin wax and cryostat sections; to compare c-erbB-2 expression in non-neoplastic and neoplastic gastric tissues.

METHODS

Adjacent blocks of tumour and non-neoplastic tissue from four gastrectomy specimens were put into a panel of 10 fixatives including acetone, B5, Bouin's fluid, Carnoy's fluid, buffered formalin, formol dichromate, zinc formalin, 4% paraformaldehyde, periodate-lysine-paraformaldehyde (PLP) and periodate-lysine-paraformaldehyde-dichromate (PLPD) before embedding in paraffin wax for sectioning. Similar tissue blocks were snap frozen and cryostat sections were postfixed in these fixatives, either alone or in combination, before immunostaining.

RESULTS

In paraffin wax embedded sections the best fixative was PLP, and in frozen tissues the best results were obtained after fixation of cryostat sections in buffered formalin followed by cold methanol and acetone. Applying these fixatives to samples from a further 16 gastrectomy specimens, strong membrane staining of c-erbB-2 protein was found in the tumour in eight of 16 cases (50%) using paraffin wax sections, and staining was stronger in the better differentiated carcinomas. For frozen tissues, positive membrane staining was found in all gastric adenocarcinomas, but differential staining intensity associated with tumour differentiation could not be detected.

CONCLUSIONS

These results indicate that fixation and paraffin wax embedding affect the results of immunohistochemical demonstration of c-erbB-2 in gastric cancer. The choice of fixative is critical in the demonstration and evaluation of c-erbB-2 protein expression by immunohistochemistry in gastric carcinomas. Staining results also vary depending on whether frozen or paraffin wax embedded tissues are studied.

A new chromosome preparation technique for Coleoptera (Insecta)

A new squash technique with Giemsa staining is described for use with Coleoptera and Tettigonidae (Orthoptera). This method yields chromosome preparations suitable for the application of banding techniques.

Different reactivity with monoclonal anti-tubulin antibodies between native and fixed mitotic microtubules in sea urchin eggs

The effect on fixation on the reactivities of mitotic microtubules with monoclonal anti-tubulin antibodies was investigated by the indirect immunofluorescence procedure. All of the seven antibodies used intensely stained mitotic microtubules in sea urchin eggs lysed and fixed with methanol at -20 degrees C, whereas only two of them stained the stabilized microtubules in the lysed eggs before the fixation. The other five did not stain the mitotic microtubules even after microtubule components other than tubulin were removed by treating the lysed eggs with 0.4 M KCl solution containing taxol. These results exclude the possibility that the fixation affects proteins, which interact with microtubules including microtubule-associated proteins (MAPs) and interfere with the binding of monoclonal antibodies with tubulin, and strongly suggest that the fixation directly affects the three-dimensional conformation of tubulin. Furthermore, microinjection of these antibodies indicated the results as follows [combining the results reported previously; Oka et al., 1990: Cell Struct. Funct. 15: 373-378]: The antibodies which stained mitotic microtubules stabilized in the lysed eggs induced disassembly of native mitotic microtubules in the living eggs, but those which did not stain the stabilized microtubules did not disassemble the native microtubules. From these results, it is suggested that the monoclonal antibodies which stain microtubules in the eggs lysed but not fixed are useful for microinjection experiments.

Low oxygen affinity derivatives of human hemoglobin by fixation of polycarboxylic dextran to the oxyform

Solutions of modified adult human hemoglobin (Hb) have potential applications as physiological oxygen carriers. The chemical modification that has been the most studied during the last few years is the cross-linking of the protein between its two alpha beta dimers, in order, first, to hamper their diffusion through the kidney and therefore increase the plasma persistence of Hb, and second, to decrease its oxygen affinity. However, despite the cross-linking, the vascular retention time is only increased by a factor of three, and a supplementary modification of cross-linked Hb is needed in order to further improve its in vivo half-life. The Hb derivatives described in this paper were obtained by the covalent fixation of benzene tetracarboxylate-substituted dextran onto oxyHb. The resulting conjugates all exhibited a higher P50 than native Hb. The experiments carried out in the presence of inositol hexaphosphate showed that the allosteric sites of Hb molecules were occupied by the polymeric reagent. The important decrease in the Bohr effect and the lack of the Cl- effect on the oxygen-binding properties proved that the Val 1 alpha residue was also substituted. Finally, the ability of some conjugates to unload as much O2 as blood, together with their other properties, make them quite promising candidates as red cell substitutes.

Non-aqueous fixative preserves macromolecules on the endothelial cell surface: an in situ study

A fixative composed of 1% w/v osmium tetroxide dissolved in a fluorocarbon (FC-72) was used to perfusion-fix rat blood vessels for this ultrastructural study. With non-aqueous fixation, the lumenal surfaces of endothelial cells in cardiac and skeletal muscles retained an extracellular coat which was morphologically consistent with glycocalyx. Venules displayed the greatest density and depth (up to 870 nm thick) of glycocalyx, but all vessel types had at least 70 nm of surface coat. The results indicate that non-aqueous fixatives will be useful in studies of the endothelial cell lumenal surface, while offering excellent preservation of general ultrastructure.

Localization of a laminin-binding protein in brain

A 110,000 mol.wt laminin-binding protein from newborn mouse brain recognizes a neurite promoting laminin A chain site and is related to the beta-amyloid precursor protein. In the present study, we examined the expression of 110,000 mol.wt laminin-binding protein in brains of adult mice, rats, and non-human primates. Essentially identical immunoreactivities were observed across species with distinct staining of cortical pyramidal neurons with apical dendrites, cerebellar basket cell axons, hippocampal mossy fibers, and fine labeling of processes throughout the brain. Colocalization of immunoreactivities to 110,000 mol.wt laminin-binding protein and to laminin in neurons of the adult rat brain was observed. Electron microscopy demonstrated that 110,000 mol.wt laminin-binding protein-like immunoreactivity is intracellular and is possibly associated with the neuronal cytoskeleton. Western blot analysis revealed that anti-110,000 mol.wt laminin-binding protein also recognizes a 140,000 mol.wt protein in the pellet, in addition to the 110,000 mol.wt protein in the Triton soluble extract. Antibody fractions specific to the two reactive protein species (110,000 mol.wt and 140,000 mol.wt) exhibited cross-reactivity on immunoblots and revealed similar immunohistochemical staining in adult brain. Results suggest a significant interaction between laminin-like molecules and 110,000 mol.wt laminin-binding protein-like molecules in normal brain function, in response to CNS injury and possibly in the pathogenesis of Alzheimer's disease.

Immunocytochemical detection of the microsomal glucose-6-phosphatase in human brain astrocytes

Using an antibody raised against the catalytic subunit of glucose-6-phosphatase, this enzyme was immunolocalized in many astrocytes in 20 normal human brains. Double immunofluorescence studies showed co-localization of glial fibrillary acidic protein (GFAP) with glucose-6-phosphatase in astrocytes. However, not all GFAP-positive cells were also glucose-6-phosphatase positive, indicating that some astrocytes do not contain demonstrable expression of this enzyme. Reactive astrocytes in a variety of abnormal brains were strongly glucose-6-phosphatase positive, but neoplastic astrocytes were often only weakly positive. Expression of the enzyme could not be demonstrated in radial glia, neurons or oligodendroglia. Astrocytes normally contain glycogen and the demonstration that some astrocytes also contain glucose-6-phosphatase indicates that they are competent for both glycogenolysis and gluconeogenesis, which may be critical for neuronal welfare.

The effect of different storage methods on the mechanical properties of trabecular bone

The effect of different storage methods on the elastic and viscoelastic properties of trabecular bone was examined using non-destructive compression tests to 0.45% specimen strain. There was a 10% decrease in stiffness during the first 24 h post mortem. Storage by freezing or in ethanol for 100 d did not change the stiffness, and neither did several thawing, testing and refreezing sequences. The viscoelastic properties were more sensitive to storage and showed significant although small changes during 100 d of storage. The effect of defatting the specimens was a 30% increase in stiffness and a 50% decrease in viscoelastic energy dissipation.

Quantitation of platelet deposition on human arteries: assessment of the disparity between results obtained with 111indium (111In)-labelling versus scanning electron microscopy

Quantitation techniques for measuring platelet deposition (PD) to vessel surfaces are important to an understanding of thrombogenesis. In previous studies, scanning electron microscopy (SEM) has been shown to indicate a lower extent of PD than platelet 111In-scintigraphy. Part of this disparity may be explained by nonspecific binding of 111In to the vessel surface during perfusion, or loss of adherent 111In-labelled platelets by lysis or dissociation from the surface during specimen preparation for SEM. To assess whether these independent processes occur, we used a previously described human placental artery (HPA) perfusion model to quantify vessel 111In retention. Of the total 111In that bound to the vessel surface during perfusion, 77 +/- 42% (N = 9) was platelet associated 111In (111In-labelled platelets) and 23 +/- 19% (N = 9) was non-platelet associated 111In (nonspecific binding). After specimen fixation, 67 +/- 32% (N = 9) of the initial total surface 111In remained. This decrease is due to dissociation of both adherent 111In-labelled platelets, and nonplatelet associated 111In. After fixation, 57 +/- 34% (N = 9) of the initial total surface 111In remained as 111In-labelled platelets and 10 +/- 13% (N = 9) remained as nonplatelet associated 111In. Fixation caused no measurable lysis of platelets. These data suggest that PD may be overestimated by 111In-scintigraphy because of nonspecific binding of 111In and underestimated by SEM because of dissociation of adherent platelets during specimen preparation for SEM.

Pathological specimens of rat temporal bone--comparison between different fixative solution

We investigated the difference in temporal bone specimens fixated by three sorts of fixative solution (10% formalin fixative, Wittmaack's fixative and Heidenhein-SuSa fixative). 1. 10% Formalin's fixative solution We found many pinkish precipitates, which are stained by hematoxy-eosin, in the scala media of the cochlea. Same substance is found in the perilymphatic space and endolymphatic space in the vestibulum. The fusion of the cells is indicated in the tectorial membrane, inner sulucus cell, outer sulucus cell especially in the apical turn of the cochlea. 2. Wittmaack's fixative solution The detachment of inner and outer sulucus cells are found from basilar membrane at the basal turn of the cochlea. The tendency in convex and concave form of the Reissner's membrane is most remarkable in these three fixative solution. 3. Heidenhein-SuSa fixative solution In this solution, no precipitates, no fusion of cells are found. No detachment of the inner or outer sulucus cells is also found. This study indicates that Heidenhein-SuSa fixation is most excellent fixative method.

Formaldehyde-fixed semen is suitable and safer for leukocyte detection and DNA amplification

This pilot study indicates the use of formalin-fixation may offer a significant advance in the cytologic and pathological evaluation of semen. We are reporting this novel method to stimulate further assessment of this safer approach to semen analysis. The immunohistochemistry and PCR methods described here may also prove useful in improving the safety of studies of pathogen-infected cells in other laboratory settings.

Histological techniques to improve testing of pulpal response of teeth to filling material

Two fixation fluids, two fixation techniques and two embedding methods were investigated for their effects on the quality of sections of teeth for pulpal response to filling materials to improve evaluation of pulpal responses. Sections from 32 baboon teeth were prepared, half with experimental cavities and half without, using either 10% formaldehyde or 4% glutaraldehyde, longitudinal tooth splitting or removal of the tooth apex, and paraffin or K plast resin embedding; decalcification in a formic acid mixture was a constant throughout. Histometric analysis showed that paraffin embedding produced less shrinkage than the K Plast resin embedding although the difference was not statistically significant. Six parameters of separation at the pulp:dentine interface were studied: embedding, fixative, presence or absence of a cavity, cutting technique and individual animal tooth type. Statistical investigation revealed that fixative, cutting technique, and fixative and cutting technique combined had significant influences on the separation artifact. Of the combinations tested the choice of embedding method depends on which of the two artifacts, shrinkage or separation, is more adverse in the opinion of the investigator. Four percent glutaraldehyde together with the longitudinal split technique of fixation, processed by either K Plast resin embedding or paraffin embedding produced satisfactory pulpal sections.

The formation of the haemostatic plug--a special case of platelet aggregation. An experiment and a survey of the literature

The formation of the haemostatic plug is an extremely fast process. This excludes, at least in its first phase, the involvement of soluble activating agents released from or produced by the platelets. An experiment with ADP-activated, formaldehyde-fixed platelets shows that platelets with activated fibrinogen receptors will bind inactive platelets in the presence of fibrinogen and Ca(2+)-ions. A survey of the literature shows that platelet activation is accompanied by the clustering of the fibrinogen receptors. The surface of an activated platelet, which makes part of the growing haemostatic plug therefore is covered with patches of tightly packed fibrinogen. This allows the multisite combination with the statistically distributed low affinity receptors of the newly arriving platelets. Tightly packed fibrinogen, as present on clusters of the activated GP IIb/IIIa receptors as well as when absorbed to artificial surfaces acts as an activator of platelets. Thus, the propagation of the activation process is possible without a requirement for other, external activators. Such agents, which are released from platelets and, finally, thrombin formation, are nonetheless of vital importance, not for the formation but for the consolidation of the haemostatic plug.

DNA amplification by polymerase chain reaction from brain tissues embedded in paraffin

A method which enables analysis of DNA from archival paraffin embedded normal and malignant brain tissue is described. The demonstration of a 317-bp long beta-actin DNA sequence by the polymerase chain reaction (PCR) was used to identify which fixation procedure, deparaffinization time and DNA extraction procedure would give the best results. Tissue specimens 1-39 years old were included in the experiments. Specimens fixed in either 10% formalin, Carnoy's or AMeX fixative were found to be best suited for subsequent analysis by PCR. Paraformaldehyde and acetone compromised amplification efficiency, while Bouin's fixed tissue gave uniformly negative results. Regardless of fixative used, PCR reaction had to be run through at least 40 cycles. Prolonged deparaffinization time and phenol/chloroform extraction of DNA did not influence DNA quality as a template for PCR reaction. Formalin fixed brain tumours can be successfully used for DNA/PCR analysis even if they are up to 39 years old.

False aneuploidy in flow cytometric DNA analysis of paraffin embedded tissue: effects of Carnoy's fixation

False aneuploidy was detected on flow cytometric DNA analysis of paraffin embedded axillary lymph nodes negative for tumor. It was hypothesized that "clearing" of axillary fat in Carnoy's solution to facilitate lymph node dissection might be responsible for false aneuploidy. Various tissues fixed overnight in Carnoy's were compared to formalin fixed paraffin embedded controls. Under these conditions no false aneuploid peaks were detected, but Carnoy's fixation did shift the G0/G1 histogram peak to the left, increase the G0/G1 CV and increase the S phase fraction relative to formalin fixed controls. It was then hypothesized that partial fixation of nodes in Carnoy's followed by formalin fixation might result in false aneuploid peaks. Twenty-two lymph nodes were partially fixed in Carnoy's for periods ranging from 5 to 60 min followed by complete fixation in formalin. Seven of these nodes did show false aneuploid peaks. By contrast, no aneuploidy was detected in formalin fixed controls. It was concluded that tissues in contact with Carnoy's solution may be a source of false aneuploidy and/or false elevation of S phase fraction. This reinforces the need for matched negative tissue controls for DNA analysis of paraffin embedded specimens whenever possible.

Improved DNA content histograms from formalin-fixed, paraffin-embedded liver tissue by proteinase K digestion

An improved method for the enzymatic digestion of formalin-fixed, paraffin-embedded liver tissue for DNA content analysis by flow cytometry is presented. Forty samples of histologically normal liver were alternately digested by the traditional pepsin method or a new method utilizing proteinase K and heat. Sixteen (40%) of the pepsin-digested samples had apparent DNA aneuploid peaks by flow cytometry. False DNA aneuploid peaks were not present in any of the histograms obtained after proteinase K digestion. Microscopy showed that the pepsin-digested samples had residual cytoplasmic remnants which contained fluorescent material. Samples digested with proteinase K had few cytoplasmic remnants. The average G0/G1 coefficient of variation after proteinase K treatment was lower (41%) and the fluorescent intensity higher (128%) than the pepsin-treated samples. The apparent mean S-phase (a combination of S-phase cells and underlying debris) after proteinase K digestion was 35% of the pepsin-treated samples. Primary and secondary tumors of the liver that were DNA aneuploid after pepsin treatment were also DNA aneuploid after proteinase K treatment. A modified digestion protocol utilizing proteinase K and heat can provide superior results for DNA content analysis of formalin-fixed, paraffin-embedded liver tissue.

Glutaraldehyde in dentistry--a review

The disinfective and fixative properties of glutaraldehyde are now widely investigated. Glutaraldehyde is effective against micro-organisms and their spores. Recently, studies have shown the effectiveness of glutaraldehyde against the HIV virus. 2% glutaraldehyde is now recommended for the sterilisation of surgical instruments, operating areas, dental impressions and root canals during endodontic therapy. Studies have also shown that glutaraldehyde is an effective fixative with minimum side effects, limited penetration and quick acting. Pulpotomy studies using glutaraldehyde as the fixative agent produce high success rates. The important feature is the vital pulpal tissue at the apical third suggesting its limited penetration. The small amounts that get distributed systemically are quickly metabolised and excreted in the urine or exhaled as carbon dioxide.

The sea urchin egg jelly coat is a three-dimensional fibrous network as seen by intermediate voltage electron microscopy and deep etching analysis

The egg jelly (EJ) coat which surrounds the unfertilized sea urchin egg undergoes extensive swelling upon contact with sea water, forming a three-dimensional network of interconnected fibers extending nearly 50 microns from the egg surface. Owing to its solubility, this coat has been difficult to visualize by light and electron microscopy. However, Lytechinus pictus EJ coats remain intact, if the fixation medium is maintained at pH 9. The addition of alcian blue during the final dehydration step of sample preparation stains the EJ for visualization of resin embedded eggs by both light and electron microscopy. Stereo pairs taken of thick sections prepared for intermediate voltage electron microscopy (IVEM) produce a three-dimensional image of the EJ network, consisting of interconnected fibers decorated along their length by globular jelly components. Using scanning electron microscopy (SEM), we have shown that before swelling, EJ exists in a tightly bound network of jelly fibers, 50-60 nm in diameter. In contrast, swollen EJ consists of a greatly extended network whose fibrous components measure 10 to 30 nm in diameter. High resolution stereo images of hydrated jelly produced by the quick-freeze/deep-etch/rotary-shadowing technique (QF/DE/RS) show nearly identical EJ networks, suggesting that dehydration does not markedly alter the structure of this extracellular matrix.