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PubMed2000

Detection of mRNAs in Peyer's patches of the developing mouse embryo.

We describe a method to identify cells expressing mRNA of interest in the developing digestive tract by whole mount in situ hybridization with digoxigenin-labeled RNA probes. In preparing samples, serosal tissue surrounding the intestine was removed. Enzymatic reactions and probe concentrations were optimized. Furthermore, polyvinyl alcohol was included in the reaction mixture for the color development of alkaline phosphatase conjugated to the antibody against digoxigenin. These modifications improved the sensitivity and enabled us to identity cells that express mRNA in embryonic intestine. Using the antisense probe for VCAM-1, the protein product of which is an immunohistochemical marker of the Peyer's patch in the embryonic intestine, cells expressing mRNA were identified as spot-like clusters in Peyer's patches, confirming the validity of the method. With this method, mRNAs of both lymphotoxins alpha and beta, key molecules for peripheral lymphoid organ development, were found to be confined to the Peyer's patch in the developing intestine. Whole mount in situ hybridization analysis is a useful tool for exploring spatio-temporal expression profiles of mRNA in the developing immune organs.

Animals↗
PubMedDate not supplied

PCR-ELISA for the detection of Brugia malayi infection using finger-prick blood.

A polymerase chain reaction assay based on the enzyme-linked immunosorbent assay (PCR-ELISA) has been developed to detect Brugia malayi infection in an area of low endemicity in Malaysia. Blood samples from 239 subjects were tested: 192 amicrofilaraemic individuals, 14 microfilaraemic persons and 3 chronic elephantiasis cases from endemic areas and 30 city-dwellers (non-endemic controls). PCR products were examined by ELISA and Southern hybridization. In the PCR-ELISA, digoxigenin-labelled PCR products were hybridized to a biotin-labelled probe. This was followed by incubation in streptavidin-coated microtitre wells and detection using anti-digoxigenin-peroxidase and ABTS [2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonic acid)]. All microfilaraemic samples were positive by PCR-ELISA and Southern hybridization and all samples from non-endemic subjects and chronic elephantiasis patients were negative. The PCR-ELISA detected 12 times as many B. malayi infections as did thick blood film examination. Nineteen of the 194 samples from the endemic area gave positive results by both PCR-ELISA and Southern hybridization, and an additional 5 samples were positive by PCR-ELISA only. The PCR-ELISA was specific and sensitive, detected more infections, and was more reproducible than Southern hybridization.

Animals↗
PubMed1998

PCR ELISA for the quantitative detection of Epstein-Barr virus genome.

A highly sensitive and nonradioactive microplate hybridization assay for the detection of Epstein-Barr virus (EBV)-specific polymerase chain reaction (PCR) product was developed. The PCR product is labelled by adding digoxigenin-dUTP directly to the reaction mixture and, after denaturation, is captured by a microtitre plate coated with an extravidin-linked biotinylated probe. Captured products are reacted with a peroxidase-conjugated anti-digoxigenin antibody and detected using tetramethylbenzidine. The assay detected less than ten EBV genomes in a background EBV-negative DNA of 0.75 microg and, when tested on clinical samples, it was able to define the viral load in throat washings of patients with acute infectious mononucleosis, immunosuppressed patients with HIV infection, and rare normal individuals who shed the virus in the oropharynx.

DNA, Viral↗
PubMed1999

A sensitive fluorescence in situ hybridization technique for detection of porcine reproductive and respiratory syndrome virus.

A sensitive fluorescence in situ hybridization (ISH) for detecting porcine reproductive and respiratory syndrome virus (PRRSV) RNA in viral infected tissue was developed using digoxigenin-labeled RNA probes targeted on the nucleocapsid gene of PRRSV. In situ RNA/RNA hybrids were detected with an anti-digoxigenin antibody alkaline phosphatase conjugate and further revealed with Fast Red TR salt/naphthol AS-MX phosphate using a fluorescent microscope. Viral nucleic acid was readily demonstrated within macrophages, known to be the major target of PRRSV. In addition, positively stained cells were found in the salivary gland and skin tissues which have not been reported to contain PRRSV infected cells before. In conclusion, the fluorescence ISH used in this study provides a fast and sensitive means for screening virus-infected tissues in which relatively few cells are affected. This advantage will be especially beneficial for studying viral persistence and for routine diagnosis of PRRSV infection.

Animals↗
PubMed1999

RT-PCR and chemiluminescent ELISA for detection of enteroviruses.

Reverse transcription followed by polymerase chain reaction amplification (RT-PCR) is now used commonly to detect the presence of enteric RNA viruses in environmental samples. A sensitive, non-isotopic microtitre plate hybridisation assay was developed and applied for detection of enteroviruses in environmental samples. Following reverse transcription, viral cDNA was labelled with digoxigenin (DIG)-dUTP during the PCR amplification step. The labelled PCR products were then hybridised with enterovirus-specific biotinylated oligonucleotide probe and captured in streptavidin-coated microtitre wells. Hybridised enteroviral PCR products were detected by an anti-digoxigenin peroxidase conjugate using either a colourimetric or a chemiluminescent substrate and automated measurement. Standard curves were established for poliovirus and other enteroviruses. The chemiluminescent assay was more sensitive than the colourimetric assay for detection of poliovirus, and was specific for enteroviruses. The chemiluminescent ELISA assay was used to confirm the presence of enteroviruses in environmental water samples.

Animals↗
PubMed2002

Porcine reproductive and respiratory syndrome virus-induced cell death exhibits features consistent with a nontypical form of apoptosis.

Porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, belongs to a group of RNA viruses that are cytopathic for macrophages and establish persistent infections. Apoptosis is the presumed mechanism of cell death in monkey kidney cell lines and porcine alveolar macrophages after infection with European PRRSV isolates. However, evidence from in vivo and in vitro studies using North American strains have failed to identify apoptosis in cells supporting virus replication and suggest that apoptosis is present in only uninfected bystander cells. The purpose of this study was to evaluate the mechanism of cell death following the infection of MARC-145 cells with wild-type (P6) and a cell culture-adapted (P136) strains derived from the North American isolate SDSU-23983. At 2 days after infection with P136, cytoplasmic blebbing and nuclear condensation were absent in monolayers containing almost 90% infected cells. By day 3, these infected cells detached and showed evidence of apoptosis, including nuclear condensation and inter-nucleosomal DNA fragmentation. Apoptosis in single infected floating cells was confirmed by the co-localization of FITC-anti-digoxigenin antibody, used to detect uridine-digoxigenin-labled nuclear DNA in a terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling assay, and Texas red-labeled PRRSV antibody. A majority of infected floating cells were also positive for the uptake of trypan blue, an indicator of necrotic cell death. These results demonstrate that apoptosis does occur in PRRSV infected cells, but is a late event during PRRSV replication and rapidly culminates in a necrotic-like death.

Animals↗
PubMed2003

Localization of swine hepatitis E virus in liver and extrahepatic tissues from naturally infected pigs by in situ hybridization.

BACKGROUND/AIMS: The objective of this study was to detect and localize the swine hepatitis E virus (HEV) in the liver and extrahepatic tissues from 20 pigs naturally infected with swine HEV. METHODS: cDNA probe 289 base pairs for swine HEV were generated by reverse transcription-polymerase chain reaction. In situ hybridization with a nonradioactive digoxigenin-labeled cDNA probe was used for the detection of swine HEV in formalin-fixed, paraffin-embedded tissues. RESULTS: When liver tissues from the pigs naturally infected with swine HEV were hybridized with the nonradioactive digoxigenin-labeled cDNA probe, a strong signal was seen in hepatocytes and bile duct. Positive hybridization signals were also detected in small and large intestine, lymph node, tonsil, spleen, and kidney. CONCLUSIONS: Swine HEV was detected primarily in the hepatocytes. Swine HEV may also replicate in tissues other than the liver. In situ hybridization described in the present study has greatly facilitated the application of in situ hybridization procedures to the clinical setting, thus allowing for the diagnosis of swine HEV infection while preserving the morphology of the tissue.

Animals↗
PubMed2003

The blue copper ceruloplasmin induces aggregation of newly differentiated neurons: a potential modulator of nervous system organization.

Ceruloplasmin (CP) is a copper-dependent ferroxidase. It regulates iron metabolism and is involved in inflammation, angiogenesis, and protection against oxidative stress. CP also modulates K(+) channel activity in neuroblastoma cells and affects cardiodynamics of isolated hearts. Considering the presence of CP in the nervous system and the importance of iron ions and K(+) channels in neuronal activity, we postulated a role of CP in neuronal development. This hypothesis was tested using the P19 mouse embryonal carcinoma cell line, a model of neuronal differentiation. Addition of CP to the culture medium of newly differentiated P19 neurons induced cell aggregation within 24 h. This effect was concentration-dependent half-maximal at 50 nM, and not associated with necrosis, apoptosis or changes in secretory function. Deglycosylated CP was aggregative but not denatured CP, copper salts, His(2)Cu complex, or other copper enzymes or serum proteins. CP-induced aggregation was less pronounced with aging neurons and seemed not to involve K(+) channels. Immunocytofluorescence analysis demonstrated that digoxigenin-labeled CP bound to P19 neurons and the proportion of responding neurons decreased with aging. The interaction of digoxigenin-labeled CP with neurons was half-maximal at 120 nM by enzyme-linked immunosorbent assay and displaced by unlabeled CP. Our data indicate a specific aggregative action of CP on young neurons in vitro, possibly involving CP receptors. A potential developmental role of CP in nervous system organization is thus demonstrated.

Animals↗
PubMed1997

Expression of glial glutamate transporters GLT-1 and GLAST is unchanged in the hippocampus in fully kindled rats.

In situ hybridization techniques and quantitative western blotting were used to study the expression of the glial glutamate transporter GLT-1 and GLAST in the brains of normal (implanted, non-kindled) and fully kindled rats. Wistar rats were implanted with stimulating electrodes in the basolateral amygdala, and killed 28 days after the stimulated group had shown stage 5 seizures on five occasions. The brains were processed for in situ hybridization of messenger RNA for GLT-1 using 35S-labelled oligonucleotide probes or digoxigenin-labelled riboprobes. Paired (kindled and non-kindled) sections were used for qualitative and quantitative analyses. Image analysis of autoradiograms showed no change in expression of GLT-1 messenger RNA in any region of the hippocampus or in the cortex. An increase in expression of GLT-1 messenger RNA (expressed as percentage difference of control) was observed bilaterally in the striatum in kindled animals (16-21%, P<0.05). Nuclear emulsion-dipped sections showed predominant glial cell labelling in the hippocampus. Particle density analysis revealed reduced cell labelling in some kindled vs control pairs but overall there was no significant reduction in labelling in CA1. Equivalent results were found in CA1 using digoxigenin-labelled riboprobes. Quantitative immunoblotting also revealed no change in GLT-1 or GLAST transporter protein in the hippocampus of kindled animals. From these data we conclude that the enduring seizure susceptibility associated with the fully kindled state is unlikely to involve alterations in hippocampal GLT-1 messenger RNA or GLT-1 and GLAST transporter protein expression.

ATP-Binding Cassette Transporters↗
PubMed1999

Comparison of two different methodologies for the detection of hepatitis B virus DNA in plasma.

In this study, two different methodologies were compared for the detection of hepatitis B virus (HBV) DNA in the plasma of 28 patients and 36 controls. Method 1 was a nested polymerase chain reaction (PCR) followed by product detection in an ethidium bromide stained gel, whereas method II was a commercial single step PCR with digoxigenin labeled product captured by a probe and then detected in a digoxigenin-antidigoxigenin enzyme-linked immunosorbent assay (DIG ELISA). The results indicate that both methods are comparable showing a concordance of 98.4%, there was no statistically significant difference in the detection rates. We feel that any one of these assays may be suitable in a clinical laboratory setting, though the commercial assay may offer some advantages to laboratories without sufficient skilled staff in trouble-shooting PCR related problems.

DNA, Viral↗
PubMed1995

Improved microplate immunoenzymatic assay of PCR products for rapid detection of Mycoplasma pneumoniae.

We developed a microtitre hybridization assay for the detection of polymerase chain reaction (PCR) amplified sequences. For this, cloned Mycoplasma pneumoniae DNA containing a sequence complementary to the PCR products is first covalently bound to microtitre wells. These coated microplates can be stored for several months. Then, an aliquot of the PCR product, labelled with digoxigenin-dUTP during its synthesis is hybridized to the immobilized DNA. The use of a rapid hybridization buffer makes this step very short (5 min). Finally, the hybridization signal is detected by an anti-digoxigenin antibody conjugated with alkaline phosphatase. Compared to Southern or other microplate hybridization techniques, this method is cheaper, involved fewer steps and allows easy handling of a large number of samples. This method was used for detection of M. pneumoniae in a series of clinical specimens.

Base Sequence↗
PubMed1998

Oxidative stress developed during the reperfusion of ischemic myocardium induces apoptosis.

Apoptosis or programmed cell death is a genetically controlled response for cells to commit suicide and, is associated with DNA fragmentation or laddering. The common inducers of apoptosis include oxygen free radicals/oxidative stress and Ca2+ which are also implicated in the pathogenesis of myocardial ischemic reperfusion injury. To examine whether ischemic reperfusion injury is mediated by apoptotic cell death, isolated perfused rat hearts were subjected to 15, 30 or 60 min of ischemia as well as 15 min of ischemia followed by 30, 60 or 120 min of reperfusion. At the end of each experiment, hearts were processed for the evaluation of apoptosis, DNA laddering. Apoptosis was studied by visualizing the apoptotic cardiomyocytes by direct fluorescence detection of digoxigenin-labeled genomic DNA using APOPTAG in situ apoptosis detection kit. DNA laddering was evaluated by subjecting the DNA obtained from the hearts to 1.8% agarose gel electrophoresis and photographed under UV illumination. The results of our study revealed apoptotic cells only in the 60 and 120 min reperfused hearts as demonstrated by the intense fluorescence of the immunostained digoxigenin-labeled genomic DNA when observed under fluorescence microscopy. None of the ischemic hearts showed any evidence of apoptosis. These results corroborated with the findings of DNA fragmentation which showed increased ladders of DNA bands in the same reperfused hearts representing integer multiples of the intenucleosomal DNA length (about 180 bp). The presence of apoptotic cells and DNA fragmentation in the myocardium were abolished by preperfusing the hearts in the presence of ebselen, which also removed the oxidative stress developed in the heart. Taken together, these results clearly demonstrate that oxidative stress developed in the ischemic reperfused myocardium induces apoptosis.

Animals↗
PubMed1994

Localization of uteroglobin mRNA by nonradioactive in situ hybridization in the pregnant rabbit endometrium.

The distribution of uteroglobin mRNA has been investigated in the endometrial compartments of the rabbit uterus during early pregnancy (day 0.5 p.c.--day 12 p.c.) using nonradioactive in situ hybridization. Digoxigenin-dUTP labeled oligodesoxy-nucleotide-probes (24mer) and an anti-digoxigenin-antibody conjugated with alkaline phosphatase were developed and used. It could be shown, that uteroglobin mRNA localization is restricted to the endometrial epithelium. There are differences in the extent of uteroglobin mRNA expression within the epithelial cells, which is in accord with our interpretation on the existence of different epithelial cell populations. From day 0.5 p.c. to day 9 p.c. the cells of the basal glands express uteroglobin mRNA continuously, whereas the proliferating surface epithelium shows a remarkable fluctuating pattern of uteroglobin mRNA expression. On day 2 p.c. the whole surface epithelium starts to express the uteroglobin message, and up to day 5 p.c. all these cells show a high level of uteroglobin mRNA expression, which drops significantly on day 6 p.c., when significant changes in the cyto-morphology of the surface epithelium for implantation occur. On day 7 p.c., there is no more uteroglobin mRNA expression in the surface epithelium, however remaining expression in the basal glands. The latter is evident up to day 9 p.c. From day 10 p.c. onwards, neither the luminal nor the deep glandular epithelium express any uteroglobin mRNA. Our observations on the cellular level have been continued in parallel studies on endometrial homogenates by Northern Blot analysis of uteroglobin mRNA (600 bases). Finally, it is discussed whether Uteroglobin mRNA may be an useful marker for the differentiation of various endometrial epithelial cell populations.

Animals↗
PubMed2000

Localisation of GABA(A) receptor subunits in the CNS using RT-PCR.

This paper presents an RT-PCR in situ histochemistry (RT-ISH) method for the detection and localisation of isoforms of the GABA(A) receptor in formalin-fixed, paraffin-embedded brain sections. RT-ISH was performed using PCR conditions already established in our laboratory for the amplification of the alpha(1-3) and beta(1-3) subunits of the GABA(A) receptor [2,5]. Initial experiments determined whether mRNA isolated from such sections was suitable for use in RT-PCR. Transcripts encoding both the alpha- and beta-subunits of the GABA(A) receptor were successfully amplified. RT-ISH, a one-step RT-PCR method, was used to amplify the transcripts and digoxigenin-labeled nucleotides were directly incorporated into the amplified products during cycling. RT-PCR products were detected using anti-digoxigenin antibody conjugated to alkaline-phosphatase and signal was visualised using light microscopy. This protocol may be used to study the expression of GABA(A) receptor isoforms in vivo and examine alterations in receptor composition during development and disease states.

Brain Stem↗
PubMed1999

Advantage of double labeled in situ hybridization for detecting the effects of glucocorticoids on the mRNAs of protooncogenes and neural peptides (TRH) in cultured hypothalamic neurons.

In order to study the effect of glucocorticoids on thyrotropin-releasing hormone (TRH) and protooncogenes, we describe a double labeled in situ hybridization method to explore this issue. The development of non-isotopic in situ hybridization histochemistry has proven to be an important tool for cellular and molecular studies in neurobiology [C.L.E. Moine, E. Normand, B. Bloch, Use of non-radioactive probes for mRNA detection by in situ hybridization: interests and applications in the central nervous system, Cell. Mol. Biol. 41 (1995) 917-923]. These methods involve the anatomic localization of labeled RNA or DNA molecules which hybridize with complementary target RNA or DNA sequences in the cell. With regard to gene expression, in situ hybridization allows the study of specific mRNA levels and the distribution between various cell types. It also allows the comparison of mRNA levels at various stages of development. Double labeled in situ hybridization is able to detect the colocalization of two different mRNAs simultaneously. Accordingly, this approach is utilized for specific studies involving the expression and distribution of TRH mRNA and the protooncogenes, c-fos/c-jun, in cultured rat hypothalamic neurons [L. G. Luo, I.M.D. Jackson, Glucocorticoids stimulate TRH and c-fos/c-jun gene co-expression in cultured hypothalamic neurons, Brain Research 791 (1998) 56-62]. Our protocol for double labeled in situ hybridization reflects a modification of a number of original protocols developed by others [H. Breitschopf, G. Suchanek, R.M. Gould, D.R. Colman, H. Lassmann, In situ hybridization with digoxigenin-labeled probes: sensitive and reliable detection method applied to myelinating rat brain, Acta Neurropathol. 84 (1992) 581-587; S. McQuaid, J. McMahon, G.M. Allan, A comparison of digoxigenin and biotin labeled DNA and RNA probes for in situ hybridization, Biotech. Histochem. 70 (1995) 147-154; E. Hrabovszky, M.E. Vrontakis, S.L. Petersen, Triple-labeling method combining immunocytochemistry and in situ hybridization histochemistry: demonstration of overlap between Fos-immunoreactive and galanin mRNA-expressing subpopulations of luteinizing hormone-releasing hormone neurons in female rats, J. Histochem. Cytochem. 43 (1995) 363-370]. This technique can be readily applied to various studies of cellular gene expression in the mammalian nervous system involving other neural peptides and transcription factors.

Animals↗
PubMed1981

Na+-K+ transport, motility and tegumental membrane potential in adult male Schistosoma mansoni.

Ouabain applied to adult male Schistosoma mansoni causes a large, non-reversible tension increase of the parasite's musculature and elimination of spontaneous contractions. The tension increase and the time-course of tension development caused by ouabain are dose dependent with significant effects obtained at 3 x 10(-6) M. Digoxin and digoxigenin act in a similar manner with a relative potency of ouabain approximately or equal to digoxin greater than digoxigenin. Lowered temperature as well as substitution of Li+ for Na+ increases muscle tension. The membrane potential recorded from the ventral tegument is also affected by treatments which interact with Na+-K+ transport systems. Ouabain (0.1 mM) causes a rapid depolarization without a significant effect on membrane resistance. The tegument is depolarized by temperature below 30 degrees C. The effect of temperature is readily reversible and the temperature sensitivity is eliminated by pretreatment with ouabain. Substitution of Li+ for Na+ also causes a depolarization of the tegument. Tracer experiments show both an increase in Na+ and a decrease in K+ in the parasite within 10 min after treatment with ouabain (1 x 10(-5) M). Decreasing temperature of the bathing medium also causes an accumulation of Na+ as well as a K+ decrease in the animals. The above results indicate a significant role for active Na+-K+ transport in muscle contraction and in maintenance of the tegumental membrane potential. The data also suggest that the Na+-K+ transport in S. mansoni may be electrogenic.

Animals↗
PubMed1992

Adaptation of a radioactive L. donovani complex DNA probe to a chemiluminescent detection system gives enhanced sensitivity for diagnostic and epidemiological applications.

The cDNA probe, Lmet2, was labelled with digoxigenin and used in a chemiluminescent system to detect fewer than 100 membrane-immobilized Leishmania parasites. The probe was found to hybridize primarily with members of the L. donovani complex but a slight cross-reaction was also observed with greater than 5 x 10(4) L. major. This cross-reaction was reduced by hybridizations in 50% formamide at 37 degrees C. Formamide also significantly reduced non-specific binding of the digoxigenin-labelled probe to the membrane support which, in hybridizations without formamide, masked the specific hybridization signal. This background was not observed with the corresponding radio-isotope labelled probe. With hybridizations in formamide the sensitivity achieved by the chemiluminescent system after exposure to film for 3 h was greater than that achieved by the isotopic system even after autoradiography for 24 h.

Animals↗
PubMed2003

Liquid chromatography coupled on-line to flow cytometry for postcolumn homogeneous biochemical detection.

The feasibility of flow cytometry as read-out principle for homogeneous cell- or bead-based assays coupled on-line to LC is demonstrated using digoxin-coated beads (Dig-Beads) and fluorescent-labeled anti-digoxin (AD-FITC) as model system. The assay is carried out in a postcolumn continuous-flow reaction detection system where the AD-FITC and Dig-Beads are simultaneously added to the eluate of an LC separation column. Binding of AD-FITC to Dig-Beads results in a constant amount of fluorescence associated with the beads, which is detected by the flow cytometer. The presence of active compounds, such as digoxin and its analogues, in the sample will results in a decrease of the AD-FITC-Dig-Bead complex and, consequently, in the bead-associated fluorescence. Hence, the bead-associated fluorescence detected is inversely related to the digoxin concentration. A data-handling algorithm was developed in-house for adequate analysis of raw data output from the flow cytometer. Various conditions that influence the performance of this novel LC-biochemical detection (LC-BCD) system were investigated to determine the optimal settings of the bead-based biochemical interaction. The optimized flow injection bead-based assay was capable of detecting very low concentrations of digoxigenin (0.5 nmol/L), digoxin (0.1 nmol/L), and gitoxigenin (50 nmol/L). The applicability of LC coupled on-line to flow cytometry was demonstrated by the individual detection of digoxin, digoxigenin, and gitoxigenin in a single LC analysis. The successful coupling of LC on-line to flow cytometry principally enables the use of a wide range of new homogeneous assay formats in LC-BCD, such as membrane-bound receptor assays, cell-binding assays, and functional cell-based assays. Next to the ability to use insoluble targets, and also multiplexing assays, i.e., performing a number of assays simultaneously, using color- or size-coded beads becomes at hand in LC-BCD.

Journal Article↗