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In the cystathionine beta-synthase knockout mouse, elevations in total plasma homocysteine increase tissue S-adenosylhomocysteine, but responses of S-adenosylmethionine and DNA methylation are tissue specific.

The cystathionine beta-synthase knockout mouse provides a unique opportunity to study biochemical consequences of a defective cystathionine beta-synthase enzyme. The present study was undertaken to assess the effect of elevated plasma total homocysteine caused by cystathionine beta-synthase deficiency on one-carbon metabolism in 10 homozygous mutant mice and 10 age- and sex-matched wild-type mice. Plasma total homocysteine levels, S-adenosylmethionine and S-adenosylhomocysteine concentrations in liver, kidney and brain were measured by HPLC. Tissue DNA methylation status was measured by in vitro DNA methyl acceptance. Plasma total homocysteine concentration in food-deprived homozygous mutant mice (271.1 +/- 61.5 micro mol/L) was markedly higher than in wild-type mice (7.4 +/- 2.9 micro mol/L) (P < 0.001). In liver only, S-adenosylmethionine concentrations were higher in the homozygous mutant mice (35.6 +/- 5.9 nmol/g) than in wild type mice (19.1 +/- 6.1 nmol/g) (P < 0.001) and tended to be lower in kidney (P = 0.07). In contrast, S-adenosylhomocysteine concentrations were significantly higher in homozygous mutant mice compared with wild-type mice in all tissues studied. Genomic DNA methylation status in homozygous mutant compared with wild-type mice was lower in liver (P = 0.037) and tended to be lower in kidney (P = 0.077) but did not differ in brain (P = 0.46). The results of this study are consistent with the predicted role of cystathionine beta-synthase in the regulation of plasma total homocysteine levels and tissue S-adenosylhomocysteine levels. However, the fact that the absence of the enzyme had differential effects on S-adenosylmethionine concentrations and DNA methylation status in different tissues suggests that regulation of biological methylation is a complex tissue-specific phenomenon.

Animals↗

Gangliosides of various rat tissues: distribution of ganglio-N-tetraose-containing gangliosides and tissue-characteristic composition of gangliosides.

Gangliosides were extracted from various tissues of rat (Wistar strain, male, 3 months old) and their structures were elucidated by enzymatic and chemical procedures including the analysis by negative ion fast atom bombardment mass spectrometry. All tissues analyzed contained gangliosides in various but characteristic concentrations. GD1a was detected in the various extraneural tissues (erythrocytes, buffy coat, bone marrow, testis, spleen, and liver) in amounts corresponding to more than 30% of total lipid-bound sialic acid, and surprisingly, it was the sole ganglioside found in buffy coat. The extraneural tissues were classified into several categories according to the nature of the asialo-oligosaccharides of gangliosides as follows: (1) gangliosides with ganglio-N-tetraose were exclusively present (buffy coat and erythrocytes), (2) the concentration of ganglio-N-tetraose-containing gangliosides was higher than that of lactose-containing gangliosides (testis and bone marrow), (3) ganglio-N-tetraose-containing gangliosides amounted to 25-30% of lactose-containing gangliosides (liver and spleen), (4) ganglio-N-tetraose-containing gangliosides amounted to 7-11% of lactose-containing gangliosides (lung and stomach), (5) more than 90% of gangliosides were lactose-containing gangliosides (heart, intestine, and kidney). In addition, the following gangliosides were characteristically detected in high concentration in the following tissues: GM4 in kidney. GM2 in bone marrow, fucosyl GM1 and GM1 in erythrocytes and GM3 with 2-hydroxy fatty acid, phytosphingosine and N-glycolylneuraminic acid in intestine.

Animals↗

Distinct HIV-1 long terminal repeat quasispecies present in nervous tissues compared to that in lung, blood and lymphoid tissues of an AIDS patient.

OBJECTIVE: To investigate the phylogenetic relationship of HIV-1 proviral long terminal repeat (LTR) variants present in postmortem samples of lymph node, spleen, lung, dorsal root ganglion and spinal cord as well as in the peripheral blood of an HIV-1-infected patient dying with AIDS. DESIGN AND METHODS: Postmortem tissues were studied by a combination of histology, cell culture and molecular analyses. The patient had a stable CD4 count of 10 x 10(6)/I during the 12 months preceding death. A 540 base-pair fragment of the LTR including U3/R/U5 was amplified using polymerase chain reaction on proviral DNA from the five postmortem tissues and peripheral blood mononuclear cells obtained 2 months prior to death. The population of viral variants was determined by sequencing at least five plasmid clones of the amplicons. The relationship between the variants present in different body sites was investigated using molecular phylogeny methods. RESULTS: HIV-1 was present in all organs analysed and correlated with the presence of abnormal histology. Genetic variation leading to divergence from the consensus sequence was more frequently present in characterized transcription factor binding sites within the LTR (P < 0.0001) although the HIV-1 LTR quasispecies in the different body sites showed similar, relatively low levels of divergence (intra-organ median heterogeneity ranging from 0.0094 to 0.017). Phylogenetic analysis showed that the spinal cord and dorsal root ganglion harboured an LTR population genetically distinct from that present in other organs and more closely related to a previously characterized neurotropic strain of HIV (strain JRcsf). CONCLUSION: The independent clustering of HIV-1 LTR variants present in spinal cord and dorsal root ganglion shows that HIV-1 LTR evolution can occur in a compartmentalized fashion. The data show that the LTR is an important region to analyse in sequence variation studies of HIV since it may play a role in nervous tissue adaptation of HIV-1 and neuropathogenicity. Outgrowth of HIV-1 LTR variants that are most fit for the utilization of tissue-specific transcription factors can occur in the nervous tissue.

Acquired Immunodeficiency Syndrome↗

Effect of formalin, acetone, and RNAlater fixatives on tissue preservation and different size amplicons by real-time PCR from paraffin-embedded tissue.

RNA recovered from paraffin-embedded tissue has been reported to be a suitable substrate for polymerase chain reaction. During tissue fixation and paraffin embedding, RNA undergoes degradation, but with certain restrictions, it can be used for gene expression studies. At the same time, formalin-fixed, paraffin embedded histopathology archives contain an unestimable collection, which could be analyzed to investigate changes in mRNA expression in pathologic processes. To decide for future tissue conservation of pathology samples, it would be reasonable to satisfy both histologic and molecular biologic needs. The effect of three different fixation methods, RNAlater (SIGMA R 0901, St Louis, MO), acetone, and formalin, were compared by histology, immunohistochemistry, and real-time PCR. To assess tissue structure preservation and antigenicity, hematoxylin-eosin staining and immunohistochemistry were performed; to assess RNA quality, RNA was extracted and the transcription of different amplicon sizes (121, 225, 406 bp for GAPDH; 166, 310, 536 bp for beta globin) were examined on human endometrium samples. The most adequate tissue preservation was found in case of formalin fixation, while there were no significant differences in the three fixatives' yields for various size real-time PCR amplicons. Longer amplicons (above approximately 225 bp) have limited use for gene expression studies, while shorter amplicons could give more reliable results.

Adult↗

The microvascular cast as a three-dimensional tissue skeleton: visualization of rapid morphological changes in tissues of the rat uterus.

A new interpretation of microvascular corrosion casting is described using examples from casts of the rat uterus taken during the oestrous cycle and early pregnancy. The casts are considered as representing a three-dimensional model of the tissue vascular space; this characteristic model or tissue skeleton is used to demonstrate transient morphological changes that may be difficult to visualize by other techniques, that may be obscured by other structures, or destroyed by conventional aldehyde fixation procedures. This new application, when supplemented by conventional histology to determine vessel distribution within the tissue and to confirm observations first made by casting, provides a technique for visualizing three-dimensional morphological changes in tissues that is accurate, relatively simple and far more rapid than the laborious method of histological serial sectioning and three-dimensional tissue reconstruction.

Animals↗

Specificity of Fcgamma receptors in human malignant tissue and normal lymphoreticular tissue.

The specificity of the Fcgamma receptors in normal spleen and liver and in malignant tissues was studied using hemadsorption to cryostat sections. Indicator cells (EA) were sheep erythrocytes (E) sensitized with rabbit IgG antibody (A). The binding of EA to sections of normal and malignant tissues was inhibited by pooled IgG of human, rabbit, and guinea pig origin and by human IgG1, and IgG3, and IgG4 myeloma proteins. Heat-aggregated IgG inhibited the binding to sections of liver and some malignant tissues more effectively than monomeric IgG. The Fc fragments of IgG were also inhibitory, but not the F(ab')2, Fab', and Facb fragments. The inhibition obtained increased with decreasing amounts of A used for sensitization of E. The inhibitory activity of IgG was abolished after partial reduction and alkylation. No inhibition was obtained with IgG2, IgM, IgA, or albumin. E sensitized with Facb or F(ab')2 fragments of A did not bind to normal or malignant tissues. The specificity of the Fc receptors in normal spleen and liver and in malignant tissues is apparently very similar.

Antibody Specificity↗

Immunohistochemical localization of CA130 in fetal tissues, and in normal and neoplastic tissues of the female genital tract.

A murine monoclonal antibody, 130-22, produced against a human lung adenocarcinoma cell line (PC-9) has been suggested as recognizing an antigenic determinant (CA130) which is different from an epitope recognized by OC125 on CA125 glycoprotein molecules. The immunohistochemical reactivity with the 130-22 antibody (anti-CA130) was examined in human fetal tissues, and normal and neoplastic tissues of female genital tracts, and compared to those using OC125. Among the fetal tissues, the amnion and the cells of coelomic epithelium and mullerian-derived epithelia reacted with anti-CA130. In normal adult tissues, cervical and endometrial gland cells, tubal epithelial cells, and ovarian surface cells reacted with anti-CA130. In addition, predecidual cells in the late secretory endometrium and decidual cells during gestation were positive. Among the neoplastic tissues, tubal and endometrial adenocarcinomas and epithelial ovarian tumors were positive for anti-CA130. There were no differences in the respective specimens between the immunohistochemical localization of anti-CA130 and of OC125. Therefore, anti-CA130 is considered to be useful in the immunohistochemical detection of CA125 glycoprotein molecules as well as OC125.

Antigens, Tumor-Associated, Carbohydrate↗

Quantification and distribution of alpha 1-adrenoceptor subtype mRNAs in human prostate: comparison of benign hypertrophied tissue and non-hypertrophied tissue.

1. There are at least three alpha 1-adrenoceptor subtypes, alpha 1a, alpha 1b and alpha 1d, in human tissues. Using an RNase protection assay, we have now determined the amount of each subtype mRNA in human prostatic tissue, for both benign prostatic hypertrophy (BPH) and non-BPH. In all tissue samples examined, the predominant subtype mRNA was alpha 1a. The total abundance of alpha 1-adrenoceptor mRNA in BPH samples was over six times that in non-BPH samples. This increase was mostly accounted for by alpha 1a, which was almost nine times as abundant in BPH samples as in non-BPH samples. The abundance of alpha 1b was almost the same between BPH and non-BPH samples, and the abundance of alpha 1d in BPH samples was about three times that in non-BPH samples. The ratio of the numbers of the subtype mRNAs, alpha 1a: alpha 1b: alpha 1d, was 85:1:14 in BPH samples and 63:6:31 in non-BPH samples. 2. In situ hybridization studies showed no significant differences in the tissue localization of alpha 1-adrenoceptor subtype mRNAs between BPH and non-BPH samples. alpha 1a and alpha 1d were clearly detected in the interstitium of the prostate, where alpha 1a was stained more intensely than alpha 1d, and the positive sites were primarily smooth muscle cells. In contrast, alpha 1b staining was very faint. 3. This increase in mRNA abundance may be directly related to the contraction of prostatic tissue that leads to obstruction of the urinary tract in BPH patients. Specifically, our data suggest that increased expression of the alpha 1a subtype may be primarily responsible for the contraction of the prostate.

Aged↗

Gestational ethanol consumption on tissue amino acid levels: decreased free histidine and tryptophan in fetal tissues with concomitant increase in urinary histamine excretion.

The effects of ethanol consumption during pregnancy on maternal, placental, and fetal tissue amino acid levels and metabolism were investigated. Pregnant Sprague-Dawley rats were given 35% ethanol-calorie liquid diet, ad libitum, from gestation day 7 to 21. Control rats were pair-fed with isocaloric sucrose substituted for ethanol. Ethanol consumption decreased fetal body weight and increased placental weight. Twenty-four amino acids were determined in six tissues (maternal plasma and liver, placenta, fetal plasma, liver, and brain) by HPLC with orthophthalaldehyde derivatization. The effects of ethanol on free amino acid levels differed from tissue to tissue. In general, ethanol affected more amino acids in maternal plasma, fetal plasma, and liver. Maternal liver, placenta, and fetal brain amino acids were more resistant to ethanol effect. Two essential amino acids, histidine and tryptophan, were consistently decreased in fetal tissues by maternal ethanol consumption. The values (ethanol vs. control, nmole/ml or g, mean +/- SEM, N = 20) of fetal plasma, liver, and brain for histidine were 51.8 +/- 6.0 vs. 85.3 +/- 4.5 (p = 0.001), 269.0 +/- 26.4 vs. 503.7 +/- 47.3 (p = 0.0004), and 117.9 +/- 7.7 vs. 154.6 +/- 8.7 (p = 0.0055), respectively; and for tryptophan were 105.7 +/- 3.1 vs. 132.2 +/- 4.1 (p = 0.0001), 128.8 +/- 3.7 vs. 144.3 +/- 6.0 (p = 0.0407), and 83.4 +/- 7.2 vs. 103.6 +/- 3.2 (p = 0.0198), respectively. Histidine was also decreased in placenta by ethanol (138.1 +/- 6.6 vs. 189.1 +/- 11.8 nmole/g, p = 0.0014).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

Augmented tissue oxygen supply during striated muscle contraction in the hamster. Relative contributions of capillary recruitment, functional dilation, and reduced tissue PO2.

To investigate the relative contributions of alterations in blood flow, capillary density, and tissue PO2 to elevated oxygen delivery in working muscle, we conducted experiments on the suffused hamster cremaster muscle, using in vivo microscopic techniques. Muscle PO2 was measured during striated muscle twitch contraction at 1 Hz. Tissue oxygenation was changed by using suffusion solutions equilibrated with 0%, 5%, 10%, 21%, or 50% oxygen. Contraction caused an increase in capillary density (capillary recruitment), whose magnitude was related to the equilibration gas and, thus, to the suffusate PO2. Capillary recruitment first increased as the oxygen content was raised, peaked with 10% oxygen, and then diminished with higher oxygen content. Arteriolar functional dilation was also observed; when oxygen was raised above 21%, dilation was decreased. The data suggest that oxygen supply is increased primarily by arteriolar conductance changes with low suffusion solution oxygen (0% to 5%), and by capillary recruitment and increased PO2 gradients above 10% oxygen. When vasomotor tone was increased by addition of norepinephrine to the suffusion medium, the changes observed were similar to those observed when oxygen was increased. Therefore, we propose that the altered microvascular responses during vasoconstriction are a function of vascular tone rather than the levels of tissue PO2. A model is proposed which may partially explain the relations among vascular tone, functional dilation, and capillary recruitment. Our data also suggest that tissue PO2 may not be precisely regulated about a narrowly defined set point in this striated muscle but that, instead, tissue PO2 is a dependent variable controlled by the integrated effects of capillary recruitment, functional vasodilation, and altered metabolism.

Animals↗

3D bone tissue growth in hollow fibre membrane bioreactor: implications of various process parameters on tissue nutrition.

New experimental evidence shows that hollow fibre membrane bioreactor (HFMB) may be applied to grow bulky bone tissues which may then be implanted into patients to repair skeletal defects. To design effective bone tissue engineering protocols, it is necessary to determine the quantitative relationships between the cell environment and tissue behaviour in HFMBs and their relationship with nutrient supply. It is also necessary to determine under what conditions nutritional limitations may occur and, hence, may cause cell death. These require that the appropriate bioreactor conditions for generating neotissues, and the nutrient transfer behaviour and chemical reaction during cell growth and extracellular matrix formation are studied thoroughly. In this paper, we aim to use an existing mathematical framework to analyse the influence of various relevant parameters on nutrient supply for bone tissue growth in HFMB. We adopt the well-known Krogh cylinder approximation of the HFMB. The model parameters (e.g., cell metabolic rates) and operating conditions for the mathematical model have been obtained from, or correspond to, in-house experiments with the exception of a few variables which have been taken from the literature. The framework is then used to study oxygen and glucose transport behaviour in the HFMB. Influence of a number of important process parameters, e.g., reaction kinetics, cell density, inlet concentration of nutrients, etc, on the nutrient distributions have been systematically analysed. The work presented in this paper provides insights on unfavourable system designs and specifications which may be avoided to prevent mass transfer limitations for growing bone tissues in HFMB.

Bioreactors↗

The tissue microarray data exchange specification: a community-based, open source tool for sharing tissue microarray data.

BACKGROUND: Tissue Microarrays (TMAs) allow researchers to examine hundreds of small tissue samples on a single glass slide. The information held in a single TMA slide may easily involve Gigabytes of data. To benefit from TMA technology, the scientific community needs an open source TMA data exchange specification that will convey all of the data in a TMA experiment in a format that is understandable to both humans and computers. A data exchange specification for TMAs allows researchers to submit their data to journals and to public data repositories and to share or merge data from different laboratories. In May 2001, the Association of Pathology Informatics (API) hosted the first in a series of four workshops, co-sponsored by the National Cancer Institute, to develop an open, community-supported TMA data exchange specification. METHODS: A draft tissue microarray data exchange specification was developed through workshop meetings. The first workshop confirmed community support for the effort and urged the creation of an open XML-based specification. This was to evolve in steps with approval for each step coming from the stakeholders in the user community during open workshops. By the fourth workshop, held October, 2002, a set of Common Data Elements (CDEs) was established as well as a basic strategy for organizing TMA data in self-describing XML documents. RESULTS: The TMA data exchange specification is a well-formed XML document with four required sections: 1) Header, containing the specification Dublin Core identifiers, 2) Block, describing the paraffin-embedded array of tissues, 3)Slide, describing the glass slides produced from the Block, and 4) Core, containing all data related to the individual tissue samples contained in the array. Eighty CDEs, conforming to the ISO-11179 specification for data elements constitute XML tags used in the TMA data exchange specification. A set of six simple semantic rules describe the complete data exchange specification. Anyone using the data exchange specification can validate their TMA files using a software implementation written in Perl and distributed as a supplemental file with this publication. CONCLUSION: The TMA data exchange specification is now available in a draft form with community-approved Common Data Elements and a community-approved general file format and data structure. The specification can be freely used by the scientific community. Efforts sponsored by the Association for Pathology Informatics to refine the draft TMA data exchange specification are expected to continue for at least two more years. The interested public is invited to participate in these open efforts. Information on future workshops will be posted at http://www.pathologyinformatics.org (API we site).

Community Health Services↗

Gene-enhanced tissue engineering for dental hard tissue regeneration: (1) overview and practical considerations.

Gene-based therapies for tissue regeneration involve delivering a specific gene to a target tissue with the goal of changing the phenotype or protein expression profile of the recipient cell; the ultimate goal being to form specific tissues required for regeneration. One of the principal advantages of this approach is that it provides for a sustained delivery of physiologic levels of the growth factor of interest.This manuscript will review the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. Part 2 will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration.

Journal Article↗

Tissue distribution and ontogeny of growth hormone receptor messenger ribonucleic acid and ligand binding to hepatic tissue in the midgestation sheep fetus.

While circulating GH concentrations are high in fetal life, skeletal growth is only slightly reduced by GH deficiency in utero. This has been explained by the relatively low binding of GH to fetal hepatic tissue, suggesting a lack of GH receptors (GHR). The GHR also recognizes ovine placental lactogen (oPL), which may have a specific role either as a fetal growth-promoting hormone or in regulating fetal metabolism. We investigated GHR expression and membrane binding of ovine (o) GH and oPL in various ovine fetal tissues and in maternal liver at different gestational stages. Singleton-bearing ewes at 51, 95, and 120 days gestation were killed. Liver, muscle, kidney, and brain samples were taken from the fetuses as well as placentas and livers from the ewes (n = 3/gestational age). GHR mRNA measured by Northern blot analysis was expressed at high levels in maternal liver at all gestational stages. A major band was observed at 4.4 kilobases (kb), and three minor bands were observed at 2.5, 1.7, and 8.1 kb. In fetal and placental tissue, only the 4.4-kb band was detected. This was present as early as day 51 of gestation in liver, kidney, lung, heart, and placenta and increased slightly with advancing gestation. On day 51, the expression of GHR mRNA in muscle was negligible, but by day 95, muscle expressed higher concentrations than fetal liver. Placental samples showed only a slight signal, with no change over the gestational range studied. In situ hybridization revealed the placental mRNA to be primarily associated with the decidua. Hepatic tissue showed specific binding to [125I]oGH and [125I]oPL from 51 days gestation. [125I]oPL showed a higher [51 days, 17.9 +/- 1.9% (mean +/- SEM); 95 days, 11.5 +/- 1.6%; 120 days, 16.3 +/- 0.9%] specific binding to the liver membranes than [125I]oGH (51 days, 2.1 +/- 0.7%; 95 days, 2.6 +/- 0.3%; 120 days, 3.5 +/- 0.4%). We conclude that oGHR are present as early as day 51 of gestation in various tissues, including liver. The message appears later in skeletal muscle than in liver. As the GH receptor binds oPL with higher potency than oGH, the parallel ontogenic changes in [125]oGH and [125]oPL binding in the liver do not support the presence of a PL receptor under independent developmental regulation.

Animals↗

Endothelin stimulates aldosterone secretion in vitro from normal adrenocortical tissue, but not adenoma tissue, in primary aldosteronism.

In addition to vasoconstriction, endothelin (ET) has been reported to show various endocrine actions in animals. However, no data have emerged concerning the effect of ET on adrenal function in humans. We, therefore, investigated the effects of ET on aldosterone and cortisol secretion from adrenocortical tissues obtained from normal subjects (n = 6) and patients with primary aldosteronism (n = 5). Adrenal tissue slices were incubated at 37 C for 120 min in modified Krebs-Ringer solution containing glucose and HEPES. ET increased aldosterone secretion from normal adrenocortical tissue in a dose-dependent manner, with an ED50 of 0.036 nmol/L, although the maximum response was small compared with that to angiotensin-II. ET also stimulated aldosterone secretion from tissues adjacent to the adenoma, but not from the adenoma, in patients with primary aldosteronism. The effects of ET on aldosterone secretion were significantly suppressed by calcium channel blockade with nicardipine. ET did not affect cortisol secretion from the adrenal tissues. These results suggest that ET is one of the factors that regulates aldosterone secretion in humans.

Adenoma↗

Percutaneous needle biopsy of localized pulmonary, mediastinal, and pleural diseased tissue with an automatic disposable guillotine soft-tissue needle. Preliminary results.

Percutaneous needle biopsy (PNB) of localized thoracic disease has become a widespread procedure in many institutions. The development of special small caliber needles has increased the diagnostic yield of PNB partly by increasing the amount of tissue from biopsy, often enabling histologic examination. Nevertheless, in a significant number of patients only cytopathologic examination is possible on the retrieved biopsy fragments, necessitating the presence of a trained cytopathologist in the biopsy room. Furthermore multiple biopsy needle passages often are required, increasing the risk for complications such as pneumothorax. We have evaluated the use of a small-caliber tissue biopsy cutting needle, consistently yielding sufficient biopsy tissue for histologic examination. In 25 pleural and mediastinal lesions, which could be biopsied without passage through aerated lung, there was a 93% sensitivity (7% false-negative results) for neoplasm and a 100% accuracy for benign disease. There were no complications. In 32 patients with lesions of 1 cm in diameter or more surrounded with aerated lung tissue, adequate histologic examination was feasible on every biopsy specimen after only one needle passage. There was an 87% sensitivity of PNB in neoplastic disease (13% false-negatives). In the patients with benign disease, there was a 100% accuracy. There was a 15.6% risk for pneumothorax. In only one patient (3%), however, was chest drainage necessary. One patient (3%) had mild hemoptysis. We conclude that percutaneous biopsy of localized pulmonary, pleural, and mediastinal lesions with a new small-caliber automatic guillotine cutting needle is safe and efficient, enabling recovery of sufficient tissue for histologic examination with a single-pass procedure, thus minimizing the risk for pneumothorax, eliminating the need for a cytopathologist in the biopsy room, and shortening the duration of the procedure.

Adult↗

Molecular analysis of complex tissues is facilitated by laser capture microdissection: critical role of upstream tissue processing.

Every tissue contains heterogeneous cell populations. Laser capture microdissection (LCM) facilitates cell isolation from complex tissues followed by molecular analysis. LCM entails placing a transparent film over a tissue section or a cytological sample, visualizing the cells microscopically, and selectively adhering the cells of interest to the film with a focused pulse from an infrared laser. The film with the procured cells is then removed from the original sample and placed directly into DNA, RNA, or protein-extraction buffer for processing. LCM has revolutionized molecular analysis of complex tissues because it combines the topographic precision of microscopy with the power of molecular genetics, genomics, and proteomics. However, the success of molecular analysis still depends on the experimental design and requires the understanding of each technical step involved in specimen preparation. This review attempts to rationalize and demystify the choice of various technical options in upstream tissue processing supporting global analytical strategies.

Animals↗

Antigen retrieval on epoxy sections based on tissue infiltration with a moderately increased amount of accelerator to detect immune complex deposits in glomerular tissue.

We wanted to examine the effect of antigen retrieval on epoxy sections where the tissue had been infiltrated by resin containing moderately increased amounts of accelerator. The concentration of accelerator DMP-30 (Tri(Dimethyl Amino Methyl) Phenol) was varied in the range of 0% to 4% in the infiltration step of the tissue processing. Some of the epoxy sections were fixed in osmium tetroxide, and for others this fixative was avoided. Immunogold labeling was performed on epoxy sections and LR-White sections of renal tissue with IgG-deposits, and the antibody used was anti-IgG. Antigen retrieval was performed by heating the sections in citrate buffer. The amount of immunogold labeling on retrieved sections increased according to the amount of accelerator the non-osmicated epoxy sections were based on in the infiltration steps. For the osmicated epoxy sections these differences were less pronounced. The immunogold labeling of retrieved epoxy sections was up to 70% of LR-White labeling. In addition to breaking fixation bond introduced by the chemical fixation, we believe that the antigen retrieval also breaks bonds between the epoxy resin and the embedded tissue. The combination of increased amount of accelerator in the tissue infiltration and antigen retrieval by heating the sections in citrate buffer is a good method for improving the immunolabeling of epoxy sections.

Animals↗