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C Crouse

Publications and source records attributed to C Crouse.

At least 19 recordsLinked to original sources
PubMed2004

Inhalation toxicity of Cyclosarin (GF) vapor in rats as a function of exposure concentration and duration: potency comparison to sarin (GB).

The inhalation toxicity of cyclohexyl methylphosphonofluoridate (GF) was examined in male and female Sprague-Dawley rats exposed by whole body in a dynamic 750-L chamber. The objectives of this study were to (1) generate GF vapor in a dynamic inhalation chamber system, starting in the lethal to near-lethal concentration range, (2) examine dose-response effects of inhaled GF vapor and analyze the relationship between concentration (C) and exposure duration (T) in determining probability of lethality, and (3) establish a lethal potency ratio between GF and the more volatile agent Sarin (GB). Using a syringe pump, GF vapor concentrations were generated for exposure times of 10, 60, and 240 min. Dose-response curves with associated slopes were determined for each exposure duration by the Bliss probit method. GF vapor exposures were associated with sublethal clinical signs such as tremors, convulsions, salivation, and miosis. Concentration-exposure time values for lethality in 50% of the exposed population (LCT(50)) were calculated for 24-h and 14-day postexposure periods for 10-, 60-, and 240-min exposures. In general, LCT(50) values were lower in female rats than males and increased with exposure duration; that is, CT was not constant over time. The GF LCT(50) values for female rats were 253 mg min/m(3) at 10 min, 334 mg min/m(3) at 60 min, and 533 mg min/m(3) at 240 min, while the values for males were 371, 396, and 585 mg min/m(3), respectively. The GB LCT(50) values for female rats were 235 mg min/m(3) at 10 min, 355 mg min/m(3) at 60 min, and 840 mg min/m(3) at 240 min, while the values for males were 316, 433, and 1296 mg min/m(3), respectively. At longer exposure durations, the LCT(50) for GF was less than that found for GB but at shorter exposure durations, the LCT(50) for GF was more than that found for GB. Empirical models, consisting of the toxic load model plus higher order terms, were developed and successfully fit to the data.

Administration, Inhalation↗
PubMed2001

Paradoxical effects of ketamine on the memory of fetuses of different ages.

Brain N-methyl-D-aspartate (NMDA) glutamate receptors have been implicated as important mediators of both learning and neuronal development. The current study investigated how ketamine (a well-known NMDA-receptor blocking drug) influences taste-mediated conditioned motor responses (CMRs) in perinatal rats. Dams pregnant with either embryonic day 18 (E18) or E19 rat fetuses were injected with 0 or 100 mg/kg ketamine HCl (i.p.). One-half hour later, a reversible spinal block was performed on the dam and fetuses received oral lavage with 10 microl, 0.3% saccharin (SAC) or water (control) in utero. After the oral injection, fetuses received either a saline (control) or lithium chloride (LiCl) injection (81 mg/kg, i.p.). The uterus was replaced and, 2 days later (E20 or E21), some rats received oral lavage with SAC. Other litters were born via normal vaginal delivery or Cesarean section and orally exposed to SAC on post-natal day 3 (P3). Motor responses were observed immediately after the oral lavage of SAC. If SAC had been paired with LiCl in utero, pups generally exhibited conditioned suppression of orofacial movements (as compared to controls). Ketamine significantly attenuated this taste-mediated CMR of animals conditioned on E19. However, the same treatments did not disrupt CMRs of rats treated with ketamine before CS-US pairing on E18. Our findings indicate an age-dependent role for NMDA receptors in the formation of CMRs in perinatal rats.

Age Factors↗
PubMed2000

Ketamine blocks a taste-mediated conditioned motor response in perinatal rats.

Brain N-methyl-D-aspartate (NMDA) glutamate receptors have been implicated as important mediators of both learning and neuronal development. The current study investigated how ketamine HCl (a well-known NMDA-receptor blocking drug) would influence taste-mediated conditioned motor responses in perinatal rats. Dams pregnant with E19 rat fetuses were injected with 0, 50, or 100 mg/kg ketamine HCl (IP). One-half hour later, a reversible spinal block was performed on the dam, and fetuses received an oral injection of 10 microl 0.3% Saccharin (SAC) or water while in utero. After the oral injection, fetuses received either saline or LiCl (81 mg/kg, IP). The uterus was replaced and, 2 days later (E21), rats received oral lavage with SAC. Rats in other litters were born via a normal vaginal delivery and were exposed to SAC on postnatal day 3 (P3). Observations of motor responses were recorded immediately after the oral lavage of SAC. If SAC had been paired with LiCl in utero, both E21 and P3 pups exhibited a conditioned suppression of orofacial movements (compared to controls). Both doses of ketamine significantly attenuated this taste-mediated conditioned motor response. These data reinforce the current conception of the fetus and neonate as sophisticated sensors and responders to the uterine and extrauterine environment. Further, our findings indicate a role for NMDA receptors in the formation of a conditioned motor response in fetal rats.

Animals↗
PubMed2000

Ketamine blocks a taste recognition memory in fetal rats.

Decisions about novelty/familiarity are critical in determining whether or not information should be attended to, and possibly encoded, for long-term storage. We have reported that fetal and neonatal rats exhibit an increase in orofacial movements (e.g., perseverative mouthing and mouth movements, and licks) upon tasting saccharin (SAC), if it was experienced previously. E19 rat fetuses can acquire this taste recognition memory and retain it for at least 5 days (P3). In the current study, we sought to evaluate the role of N-methyl-D-aspartate (NMDA) receptors in establishing a taste recognition memory. Pregnant Sprague-Dawley rats received ketamine (NMDA receptor antagonist) (doses: 0, 50, or 100 mg/kg, i.p.). One-half hour later, we performed a reversible spinal block on each pregnant dam, and E19 fetuses received an oral injection of 10 microl, 0.3% SAC or water (control) while in utero. The uterus was replaced and the pups were later born via a normal vaginal delivery. On P3, all pups experienced oral lavage of 10 microl, 0.3% SAC, and motor responses were recorded. As expected, non-drugged control neonates tasting familiar SAC exhibited significantly more perseverative mouth movements, as well as total mouth movements and licks, than did pups tasting novel SAC. However, this taste recognition memory response was not observed in rats exposed to ketamine in utero. The data suggest that early non-associative taste memories may be disrupted by NMDA receptor blockade.

Animals↗
PubMed1996

Validation of multiplex polymorphic STR amplification sets developed for personal identification applications.

Polymorphic short tandem repeat (STR) loci, which typically consist of variations in the number of 3-7 base pair repeats present at a site, provide an effective means of personal identification. Typing can be accomplished by amplification of genomic DNA using the polymerase chain reaction (PCR) and locus-specific primers, separation of amplified alleles using gel electrophoresis and their display using silver staining or fluorescent detection. Primers for several STR loci can be combined in a single multiplex reaction so typing of multiple loci can be accomplished rapidly and with less DNA than required if each locus were analyzed separately. Before such muliplex systems are used in forensic or paternity applications, it is desirable that they undergo testing for their reliability. This study evaluates the performance of two STR triplex systems, one containing the loci HUMCSF1PO, HUMTPOX, and HUMTH01, and the other containing HUMHPRTB, HUMFESFPS, and HUMVWFA31. Protocols for amplification of these two triplexes, and their corresponding monoplexes, were evaluated for sensitivity of detection, resistance to changes in the annealing temperature of the amplification protocol, and the ability to identify the minority contributor in amplification of mixed samples. In addition, five laboratories determined the alleles of twenty DNA samples, each extracted by one of four different extraction methods. The results illustrate that the two STR triplex systems and the monoplex systems contained within them can be used with as little as 0.25 ng of DNA template. Both triplexes amplified with 100% success using the Perkin Elmer Model 480 thermal cycler. With the GeneAmp 9600 System, the CTT triplex amplified with 100% success and the HFv triplex in 95.6% of attempts. These experiments meet many requirements for use in validation of DNA typing systems for forensic cases and paternity identification.

Anthropology, Physical↗
PubMed1995

Identification of ABO alleles on forensic-type specimens using rapid-ABO genotyping.

Historically, forensic and clinical laboratories utilize serological techniques to identify ABO blood types. These techniques rely on the detection of ABO-associated proteins and are sensitive with very accurate results. This laboratory has simplified the identification of ABO types by taking advantage of previously reported ABO DNA sequence differences. The Rapid-ABO technique involves a two-step process: (i) amplification of DNA samples using primer sets specific for the ABO alleles and (ii) electrophoresis and visualization of amplified ABO fragments on a 3% MetaPhor agarose gel. The major advantage of the Rapid-ABO technique is the identification of ABO genotypes compared to serological tests for ABO phenotypes. This two-step process identifies six possible ABO genotypes including AB, AA, BB, AO, BO and OO. The Rapid-ABO protocol works well with DNA extracted organically or using Chelex 100. Results can be obtained in less than a day utilizing 2 ng of DNA in the amplification reaction. Analysis of 23 animal species shows the Rapid-ABO primers amplify ABO alleles from only human, chimpanzee and gorilla DNA.

ABO Blood-Group System↗
PubMed1991

Effect of concurrent graft-versus-host reaction on tissue distribution and infectious titer of murine cytomegalovirus.

Infection with cytomegalovirus is a major concern following bone marrow transplantation. Previously, we have described a model whereby infection by MCMV concurrent with the injection of parental strain lymphoid cells into F1 recipient mice results in a severe graft-versus-host reaction (GvHR) when the donor and host differ at the class I MHC locus (i.e., class I MHC disparate GvHR). The present studies were performed to determine whether one consequence of this severe GvHR is the alteration of the tissue distribution and/or levels of infectious virus as compared to mice not undergoing GvHR. Using PCR to detect MCMV DNA, it was observed that the tissue distribution of virus 3 days after injection was identical in recipients of virus alone and of GvHR plus virus inocula. At two weeks post injection, virus was recovered from the salivary gland and pancreas in both groups. In contrast to recipients of MCMV alone, lung tissue from GvHR plus virus mice also contained viral DNA. Notably, these results were corroborated by the plaque assay. Moreover, salivary gland and pancreas from recipients of GvHR plus virus were found to contain higher titers of infectious virus. In total, the data demonstrate that, with the notable exception of the lung, the distribution of virus was not changed in the animals despite the presence of a concurrent severe GvHR. However, viral replication in infected tissues appeared less restricted in these recipients.

Animals↗
PubMed1990

VCAM-1 on activated endothelium interacts with the leukocyte integrin VLA-4 at a site distinct from the VLA-4/fibronectin binding site.

Cytokine-activated human endothelial cells express vascular cell adhesion molecule-1 (VCAM-1), which binds lymphocytes. We now identify the integrin VLA-4 as a receptor for VCAM-1 because VLA-4 surface expression on K-562 cells (following transfection of the VLA alpha 4 subunit cDNA) resulted in specific cell adhesion to VCAM-1, and anti-VLA-4 antibodies completely inhibited VCAM-1-dependent cell-cell attachment. In addition, VLA-4 expression allowed K-562 cells to attach to the heparin II binding region (FN-40) of fibronectin. However, VLA-4/VCAM-1 and VLA-4/FN-40 interactions are readily distinguishable: only the former was inhibited by the anti-VLA-4 monoclonal antibody HP1/3, and only the latter was inhibited by soluble FN-40. The VCAM-1/VLA-4 ligand-receptor pair may play a major role in the recruitment of mononuclear leukocytes to inflammatory sites in vivo.

Animals↗
PubMed1990

Amplification of Epstein-Barr virus genomic sequences in blood cells, lacrimal glands, and tears from primary Sjögren's syndrome patients.

Based on observations of primary Sjögren's syndrome (SS) following acute Epstein-Barr virus (EBV) infection, the authors hypothesized that EBV may play a role in the pathogenesis of SS. This hypothesis was tested by evaluating ten peripheral blood mononuclear (PBMN) cell specimens, ten lacrimal gland biopsies, and five tear specimens from 15 EBV-seropositive primary SS patients for EBV genomic sequences using polymerase chain reaction (PCR). Epstein-Barr virus DNA sequences were detected in 50% of SS PBMN cell specimens and 80% of SS lacrimal gland and tear specimens. In six SS patients, specimens were obtained from two or more sites (i.e., PBMN cell and lacrimal gland and/or tears), and EBV genomic sequences were amplified in the PBMN cells and the lacrimal gland or tears in three of these subjects. The authors previously detected EBV genomes in 32% (11/34) of normal human lacrimal glands from EBV-seropositive donors using PCR and concluded that the normal human lacrimal gland may be a site of EBV persistence; however, they were unable to amplify EBV sequences in DNA from PBMN cells or tear specimens from normal donors. Amplification of EBV DNA in PBMN cells, lacrimal glands, and tears of primary SS patients at a greater frequency (P less than 0.01) than normal controls suggests that EBV may be a risk factor in the pathogenesis of SS.

Antibodies↗
PubMed1989

Analysis of the tumor-associated antigen TSP-180. Identity with alpha 6-beta 4 in the integrin superfamily.

The tumor-associated antigen complex, TSP-180, was previously defined in carcinoma cell lines and found to be expressed in higher amounts in tumor than in normal tissue. Here, the mouse TSP-180 complex is shown to consist of three related proteins (bands 1, 2, and 3) associated with a distinct protein (band 5) that is probably derived from a precursor protein (band 4). All of these proteins are cell surface glycoproteins, and the largest protein (band 1) can be readily labeled with 32PO4. The mouse TSP-180 complex described here strongly resembles the recently described human integrin alpha 6-beta 4 complex. This homology was confirmed using two distinct rat anti-alpha 6 monoclonal antibodies, each of which recognized both human alpha 6-beta 4 and mouse TSP-180 complexes. Furthermore, the TSP-180 band 5 protein (mouse alpha 6) had an N-terminal sequence identical to that of human alpha 6. Finally, two different monoclonal antibodies are described, 346-11A and 439-9B, which directly recognize the multiple forms of mouse and human beta 4 proteins, respectively.

Animals↗
PubMed1989

Association of the VLA alpha 6 subunit with a novel protein. A possible alternative to the common VLA beta 1 subunit on certain cell lines.

On platelets and other cell types, VLA-6 is a typical integrin heterodimer, with alpha 6-beta 1 subunit association. However, on colon carcinoma cell lines and other epithelial cells the alpha 6 subunit associates with a novel protein (called beta 4) rather than the VLA beta 1 subunit. The beta 4 protein differs from beta 1 because (i) it is not recognized by anti-beta 1 antibodies, (ii) it yields different V8 protease cleavage products, (iii) it has a more limited cell distribution, (iv) it has multiple forms, each larger in size than beta 1, and (v) it is susceptible to protease digestion which does not effect beta 1. Although different in many respects, the beta 4 subunit does have partial N-terminal sequence similarity to the already defined integrin beta 1, beta 2, and beta 3 subunits. The presence of alpha 6-beta 4 complexes was demonstrated by coprecipitation of beta 4 with an anti-alpha 6 antibody and by covalent cross-linking experiments. Although alpha 6-beta 4 complexes were present on certain cells, other VLA alpha subunits on those same cells remained associated with the VLA beta 1 subunit to form typical VLA heterodimers (e.g. VLA-1, VLA-2, VLA-3). By the criteria of N-terminal amino acid sequencing, antibody recognition, V8 peptide maps, and reduced/nonreduced gel migration, the alpha 6 subunit which associates with beta 4 appears identical to the alpha 6 associated with the VLA beta 1 subunit on platelets and other cell types. The beta 4 subunit may be of major importance because (i) it is highly abundant on the surface of colon carcinoma cell lines, and (ii) it is highly immunogenic relative to other surface proteins.

Amino Acid Sequence↗
PubMed1989

Regulation of cell adhesion receptors by transforming growth factor-beta. Concomitant regulation of integrins that share a common beta 1 subunit.

Cell adhesion to extracellular matrices is mediated by a set of heterodimeric cell surface receptors called integrins that might be the subject of regulation by growth and differentiation factors. We have examined the effect of transforming growth factor-beta 1 (TGF-beta 1) on the expression of the very late antigens or alpha beta 1 group of integrins in human cell lines. The six known members of this family share a common beta 1 subunit but have distinct alpha subunits that confer selective affinity toward type I collagen, fibronectin, laminin, and other as yet unknown cell adhesion proteins. Using a panel of specific antibodies and cDNA probes, we show that in WI-38 lung fibroblasts TGF-beta 1 elevates concomitantly the expression of alpha 1, alpha 2, alpha 3, alpha 5, and beta 1 integrin subunits at the protein and/or mRNA level, their assembly into the corresponding alpha beta 1 complexes, and their exposure on the cell surface. The rate of synthesis of total alpha subunits relative to beta 1 subunit is higher in TGF-beta 1-treated cells than in control cells. The characteristically slow (t1/2 approximately 10 h) rate of beta 1 conversion from precursor form to mature glycoprotein in untreated cells increases markedly (to t1/2 approximately 3 h) in response to TGF-beta 1. The results suggest that in WI-38 fibroblasts the beta 1 subunit is synthesized in excess over alpha subunits, and assembly of beta 1 subunits with rate-limiting alpha subunits is required for transit through the Golgi and exposure of alpha beta 1 complex on the cell surface. TGF-beta 1 does not induce the synthesis of integrin subunits that are not expressed in unstimulated cells, such as alpha 4 and alpha 6 subunits in WI-38 fibroblasts. However, alpha 4 and alpha 6 subunits can be regulated by TGF-beta in those cells that express them. The results suggest that TGF-beta regulates the expression of individual integrin subunits by parallel but independent mechanisms. By modifying the balance of individual alpha beta 1 integrins, TGF-beta 1 might modulate those aspects of cell migration, positioning, and development that are guided by adhesion to extracellular matrices.

Acetylglucosaminidase↗
PubMed1989

The primary structure of the alpha 4 subunit of VLA-4: homology to other integrins and a possible cell-cell adhesion function.

VLA-4 is a cell surface heterodimer in the integrin superfamily of adhesion receptors. Anti-VLA-4 antibodies inhibited cytolytic T cell activity, with inhibitory activity directed against the effector T cells rather than their targets. Thus, whereas other VLA receptors appear to mediate cell--matrix interactions, VLA-4 may have a cell--cell adhesion function. To facilitate comparative studies of VLA-4 and other integrins, cDNA clones for the human alpha 4 subunit of VLA-4 were selected and then sequenced. The 3805 bp sequence encoded for 999 amino acids, with an N-terminus identical to that previously obtained from direct sequencing of purified alpha 4 protein. The alpha 4 amino acid sequence was 17-24% similar to other integrin alpha chains with known sequences. Parts of the alpha 4 sequence most conserved in other alpha chains include (i) the positions of 19/24 cysteine residues, (ii) three potential divalent cation binding sites of the general structure DXDXDGXXD and (iii) the transmembrane region. However, alpha 4 stands apart from all other known integrin alpha subunit sequences because (i) alpha 4 has neither an inserted I-domain, nor a disulfide-linked C-terminal fragment, (ii) its sequence is the most unique and (iii) only alpha 4 has a potential protease cleavage site, near the middle of the coding region, which appears responsible for the characteristic 80,000 and 70,000 Mr fragments of alpha 4.

Amino Acid Sequence↗
PubMed1989

A novel monoclonal antibody, 1B3.1, binds to a new epitope of the VLA-1 molecule.

A monoclonal antibody, 1B3.1, was raised against a cloned IL-2-dependent T cell line that expresses the T gamma delta T cell receptor. MoAb 1B3.1 reacted with long-term cultured T cell lines of both T gamma delta and T alpha beta lineage, and with in vivo-stimulated T cells, derived from synovial fluid, but not with resting or short-term activated T cells, B cells, or macrophages. Immunoprecipitation of the 1B3.1 target antigens showed that 1B3.1 recognizes a 200/110 kDa molecule that is identical to the VLA-1 heterodimer precipitated by MoAb TS2/7. 1B3.1, however, binds to an epitope of VLA-1 that is distinct from the TS2/7 binding site. This new MoAb could be useful in further studies of the functions of VLA-1, and of the cells that express this molecule.

Antibodies, Monoclonal↗
PubMed1988

Multiple very late antigen (VLA) heterodimers on platelets. Evidence for distinct VLA-2, VLA-5 (fibronectin receptor), and VLA-6 structures.

After removal of very late antigen (VLA) 2 material from a radiolabeled detergent lysate of platelets, another VLA heterodimer was precipitated using antibody to the common VLA beta subunit. This structure was identified as VLA-5 because it contained VLA beta plus an alpha subunit that was (i) recognized by anti-alpha 5 antibodies and (ii) cleaved by V8 protease to yield a characteristic alpha 5-like pattern of peptide fragments. Besides VLA-2 and VLA-5, a third heterodimer, here named VLA-6, was also present on platelets. VLA-6 (an alpha 6 beta complex) was defined using the monoclonal antibody GoH3 (Sonnenberg, A., Janssen, H., Hogervorst, F., Calafat, J., and Hilgers, J. (1987) J. Biol. Chem. 262, 10376-10383). Although it resembled VLA-5 in size, VLA-6 was different from VLA-5 because (i) removal of the alpha 5 subunit did not remove alpha 6, (ii) removal of alpha 6 by the GoH3 antibody did not remove alpha 5, (iii) the alpha 5 and alpha 6 subunits had very distinct one-dimensional V8 peptide maps, and (iv) the alpha 6 and alpha 5 subunits had distinct migration patterns on two-dimensional O'Farrell gels. The beta subunit of VLA-6 was identified as the common VLA beta subunit because (i) it was recognized by anti-VLA beta antibody and (ii) it yielded a V8 protease cleavage map characteristic of beta. VLA-6 was not readily seen in anti-VLA beta immunoprecipitations, apparently because the alpha 6 subunit is only loosely or partially associated with the VLA beta subunit. Because VLA-5 and VLA-6 both closely resemble the previously defined Ic-IIa platelet protein complex, it is likely that there is more than one platelet "Ic" protein complexed with IIa.

Antibodies, Monoclonal↗