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Biomedical subjects

C L Miller

Publications and source records attributed to C L Miller.

At least 55 records · Page 3Linked to original sources
PubMed1993

Separation of neuropeptide Y diastereomers by high-performance liquid chromatography and capillary zone electrophoresis.

Separation of analogues of neuropeptide Y (NPY) in which a single D-amino acid replaced the corresponding naturally occurring residue was performed by chromatographic techniques to ensure the quality of the synthetic peptides to be used for structural and biological studies. Of the 35 compounds, 28 were easily separated (alpha = 1.02-2.76) from native NPY by standard reversed-phase high-performance chromatography (RP-HPLC) methods using a Vydac C18 column and a gradient buffer system developed in our laboratory comprised of triethylammonium phosphate (TEAP) at pH 2.25 and acetonitrile at 40 degrees C. The identical diastereomers could be separated on the same solid support and by using 0.1% trifluoroacetic acid (TFA) as the mobile phase modifier, however separation factors were smaller and retention times were longer. Three of the remaining seven unresolved analogues were separated (alpha = 1.02-1.96) by changing the solid-phase support to Vydac diphenyl derivatized silica and a buffer system consisting of 0.1% TFA and acetonitrile. Of the four remaining unresolved analogues, only two could be separated by capillary zone electrophoresis (CZE) in 0.1 M sodium phosphate at pH 2.5, but all four were finally resolved by changing the electrophoretic buffer to 0.1 M TEAP buffer at pH 2.5. Migration times of the diastereomers differed by 0.2-2.0 min from that of the natural NPY. In addition to confirming the uniqueness of each isomer, this investigation demonstrated the expansive utility and high efficiency of the TEAP buffer system for both RP-HPLC and CZE as well as the difference in selectivity produced by the TEAP and TFA buffers in RP-HPLC.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Meiotic recombination within the H-2K-H-2D interval: characterization of a panel of congenic mice, including 12 new strains, using DNA markers.

Intra-H-2 recombinant congenic strains are widely used to localize traits to specific subregions of the major histocompatibility complex and have provided evidence for the existence of meiotic recombinational hotspots in mammals. Forty-seven intra-H-2 recombinant strains, including 12 not previously reported, have been identified by serological typing in our laboratory. We have extended the analysis of the crossover sites in these mice using DNA markers for Ab, Aa, Eb, Ea, Cyp21-ps, D17Tu3, Bat7, and Bat5. The recombinant chromosomes of these congenic strains include loci derived from the a, b, f, k, p, q, r, s, u, and v haplotypes of H-2, providing a diverse panel of strains. Although some alleles of Bat7 could not be distinguished from one another, results from the majority of strains indicated a probable gene order of C4Slp/D17Tu3-Bat7-Bat5-H-2D. No recombinants between Cyp21-ps, C4Slp, and D17Tu3 were observed. The crossover sites in 31 of the 47 intra-H-2 recombinants were within the C4Slp/D17Tu3-H-2D interval; of these 31 crossovers, three were bracketed by D17Tu3 and Bat7, ten by Bat7 and Bat5, seven by Bat5 and H-2D, and 11 by D17Tu3 and Bat5. The results from all 47 strains suggest recombinational hotspots within the C4Slp/D17Tu3-H-2D interval and emphasize the influence that specific haplotypes can have on preferred crossover sites.

Animals↗
PubMed1993

Occipitocervical fixation in nontraumatic upper cervical spine instability.

Ten patients requiring occipitocervical fixation were reviewed: five were unstable secondary to rheumatoid arthritis, one had Klippel-Feil, and four had neoplastic disease. Patients with nonneoplastic disease improved, having decreased pain, decreased paresthesias, and increased ambulation. Patients with neoplastic disease improved significantly after the surgery, but eventually died from different tumors. The technique found to be most efficient was the placement of an intraoperatively contoured Luque rectangle wired from the occiput to appropriate cervical spine levels.

Adult↗
PubMed1993

Induction of a proteoglycan core protein mRNA in mouse T lymphocytes.

The mouse T lymphocyte cell line EL4.E1 synthesizes a proteoglycan core protein (PGCP) mRNA which is identical to serglycin mRNA found in mouse bone marrow-derived mast cells and a mouse mastocytoma cell line. PGCP mRNA was strongly induced in EL4.E1 cells by phorbol myristate acetate, which also induces mRNAs for several cytokines in these cells. In contrast to the induction of cytokine mRNAs, however, the induction of PGCP mRNA was not inhibited by Cyclosporine. PGCP mRNA was also inducible by allogeneic stimulation of normal mouse spleen cells, and by Con A stimulation of an Interleukin 2-producing T hybridoma cell line. A number of other cell lines expressed an identical or similar, mRNA, including two cytotoxic T cell lines, and three tumor cell lines related to bone marrow-derived cells. The levels of several proteoglycans have previously been reported to increase in cells of bone marrow origin under activating conditions, but this appears to be the first report of an induction of the corresponding PGCP mRNA by immune stimulation of T lymphocytes.

Animals↗
PubMed1993

Medial septal neuron activity in relation to an auditory sensory gating paradigm.

Neurons in the medial septal nucleus were recorded extracellularly in response to auditory stimuli in chloral-hydrate-anesthetized rats. Two populations of neurons were identified, both of which were localized to the nucleus by horseradish peroxidase labeling. The auditory-responsive population was characterized by slow axonal conduction velocity, as measured after antidromic activation from the fornix. This population probably represents cholinergic neurons with unmyelinated or thinly myelinated axonal projections to the hippocampus. The other population was not auditory-responsive and had relatively fast conduction times. This population was most likely GABAergic neurons, which have heavily myelinated axons. The timing of discharge within the medial septal nucleus suggests that its cholinergic neurons may regulate the response of the hippocampus to auditory stimuli by influencing the activity of both pyramidal cells and interneurons. The medial septal nucleus may thus play a critical role in the gating of the response to repeated auditory response in the hippocampus.

Acoustic Stimulation↗
PubMed1993

Metastasis of a myxoid leiomyosarcoma via the renal and hepatic portal circulation in a sarus crane (Grus antigone).

A 12-year-old female sarus crane (Grus antigone) developed a recurrent proliferative lesion in the subcutaneous tissue of the tarsometatarsus, which failed to respond to medical and surgical therapy. The crane was killed and microscopic examination of the tissues taken at necropsy revealed a myxomatous, poorly-differentiated sarcoma with metastasis to the liver and kidney. Immunohistochemical staining for muscle actin, smooth muscle myosin and vimentin were positive, indicating that the primary and metastatic tumours were leiomyosarcomas. Location of the metastatic lesions in only the portal venous system of the liver and veins of the kidney indicated that the route of metastasis was the portal circulation via the ischiatic vein, caudal mesenteric vein and both the renal-portal shunt and hepatic portal vein. This is the first report of metastatic subcutaneous leiomyosarcoma in an avian species.

Actins↗
PubMed1993

The last seven transmembrane and carboxy-terminal cytoplasmic domains of Epstein-Barr virus latent membrane protein 2 (LMP2) are dispensable for lymphocyte infection and growth transformation in vitro.

Specifically mutated Epstein-Barr virus (EBV) recombinants which truncate latent membrane protein 2A (LMP2A) and LMP2B after 260 of 497 amino acids and after 141 of 378 amino acids, respectively, were constructed. Despite truncation before the last seven transmembrane domains and the carboxy terminus, the mutant recombinants were not altered in initiation of primary B-lymphocyte infection or growth transformation, in expression of nuclear protein 1 or 2 or LMP1, or in induction of lytic EBV replication. Cells transformed by mutant virus recombinants were not different from wild-type virus transformants in initial or long-term outgrowth, sensitivity to limiting cell dilution, serum requirement, or clonogenic growth in soft agar. Together with similar analyses of a mutation stopping translation of the LMP2A amino-terminal cytoplasmic domain, these results indicate that LMP2 is not required for primary B-lymphocyte infection in vitro.

Alleles↗
PubMed1993

Epstein-Barr virus latent membrane protein 2A blocks calcium mobilization in B lymphocytes.

LMP2A is expressed in latent Epstein-Barr virus (EBV) infection and interacts with LMP1 and members of the src tyrosine kinase family in the plasma membrane. Since tyrosine kinase mediate receptor-induced changes in intracellular free calcium, the effect of LMP2A on receptor-mediated intracellular calcium mobilization was evaluated by stably expressing LMP2A in an EBV-negative Burkitt tumor cell line (BJAB) or in LMP1-converted BJAB cells. LMP2A significantly blocked calcium mobilization following class II, CD19, or immunoglobulin M cross-linking. LMP2A effects were partially reversed in LMP1-converted cell lines. These results are compatible with LMP2A acting in latent B-lymphocyte infection to downmodulate LMP1 effects on cell growth or to inhibit induction of lytic EBV infection in specific human tissues following receptor ligation.

Antigens, CD↗
PubMed1993

Deletion of DNA encoding the first five transmembrane domains of Epstein-Barr virus latent membrane proteins 2A and 2B.

A recombinant Epstein-Barr virus (EBV) was constructed, with a positive-selection marker inserted at the site of a deletion of a DNA segment which encodes the first five transmembrane domains of LMP2A and LMP2B. Despite the mutation, the mutant recombinant EBV was able to initiate and maintain primary B-lymphocyte growth transformation in vitro. Cells transformed with the mutant recombinant were not different from wild-type virus transformants in initial or long-term outgrowth, sensitivity to limiting cell dilution, or serum requirement. Expression of EBNA1, EBNA2, EBNA3A, EBNA3C, and LMP1 and permissivity for lytic EBV infection were also unaffected by the LMP2 deletion mutation. These results complete the molecular genetic studies proving LMP2 is dispensable for primary B-lymphocyte growth transformation, latent infection, and lytic virus replication in vitro.

Amino Acid Sequence↗
PubMed1992

Taurine allosterically modulates flunitrazepam binding to synaptic membranes.

Taurine is hypothesized to exert its inhibitory neuromodulatory effects, in part, by interaction with the GABAA receptor. Although taurine displaces GABA agonist binding to synaptic membranes, its allosteric effects on the benzodiazepine recognition site of the GABAA receptor complex is unsettled. We determined the effects of taurine on [3H]flunitrazepam (Flu) binding to well-washed, frozen-thawed synaptic membranes prepared from rat cortex. Comparative binding studies were conducted at 37 degrees C and on ice (0-4 degrees C). At 37 degrees C taurine increased Flu binding in a concentration dependent way by interaction with a bicuculline sensitive site, similar to GABA. Taurine increased Flu binding by causing a decrease in KD. The maximal effectiveness of taurine on Flu binding could not be increased further by addition of GABA. In contrast, the maximal stimulation of Flu binding by GABA was decreased by addition of taurine to the level attained by taurine alone. These mixed agonist/antagonist effects of taurine are pharmacologically specific and qualify taurine as a partial GABA agonist in this type of allosteric interaction. However, taurine causes opposite effects on Flu binding when measured at 0-4 degrees C: taurine interacts with a bicuculline insensitive site to inhibit Flu binding by increasing the KD. Taurine inhibition of Flu binding is not overcome by increasing concentrations of GABA. Although the mechanism of taurine inhibition of Flu binding at 0-4 degrees C is unclear, it may be an indirect effect of taurine interaction with membrane phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Phencyclidine and auditory sensory gating in the hippocampus of the rat.

The psychotomimetic drug 1-(1-phenylcyclohexyl) piperidine (PCP, phencyclidine) was found to cause a deficit in the gating of the response of the hippocampal neuron to repeated auditory stimuli, which is similar to a particular physiological feature observed in human psychosis. Other drugs, with sigma agonist and/or N-methyl-D-aspartate (NMDA) antagonist effects, were administered and their ability to cause a loss of auditory gating was compared to that of PCP. The rank order of effectiveness was levoxodrol > PCP and (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801) > N-allylnormetazocine (SKF 10047) > dexoxodrol > 3-(+/-)2-carboxypiperazine-4-yl) propyl-1-phosphonate (CPP). Further studies of two of the drugs, PCP and MK-801, showed that selective lesioning of the noradrenergic input with the neurotoxin DSP4, as well as less selective depletion of monoamines with reserpine, blocked the loss of gating. Phencyclidine, and other drugs with the same spectrum of action, most likely disrupt gating by increasing noradrenergic activity through a sigma mechanism.

Acoustic Stimulation↗
PubMed1992

GABAA receptor function and regional analysis of subunit mRNAs in long-sleep and short-sleep mouse brain.

The greater sensitivity of long-sleep (LS), as compared with short-sleep (SS), mice to ethanol is due in part to differences in GABAA receptor function in specific brain regions. To determine if differences in subunit composition of GABAA receptors contribute to this differential sensitivity, we measured alpha 1 and gamma 2 subunit mRNAs with Northern analysis and in situ hybridization and gamma 2S, gamma 2L and alpha 6 subunit mRNAs with polymerase chain reaction (PCR) amplification. No differences in mRNAs in whole brain were apparent by Northern analysis. In situ hybridization revealed that alpha 1 and gamma 2 subunit mRNAs were co-localized in many brain regions but that they still had distinct patterns of hybridization. However, the few differences observed between LS and SS mice in the levels of hybridization for these subunits did not show a regional distribution consistent with ethanol sensitivity differences. Similar ratios of gamma 2L, and gamma 2S subunit mRNAs were found in LS and SS mouse cerebral cortex and hippocampus, and both mouse lines expressed essentially only gamma 2L subunit mRNA in cerebellum. mRNA for the alpha 6 subunit was detected only in cerebellum and also was qualitatively similar between LS and SS mice. Studies of muscimol-stimulated 36Cl- uptake by cortical membrane vesicles confirmed earlier findings that ethanol does not enhance function of GABAA receptors in SS mice when assayed at 30 degrees C. However, at 34 degrees C ethanol did increase this function in SS mice although the enhancement remained greater in LS mice. These functional results, together with the results showing similar levels of alpha 1, gamma 2S, gamma 2L and alpha 6 subunits in LS and SS mice, suggest that the ethanol-insensitivity of SS mouse GABAA receptors cannot be due solely to lack of subunits required for ethanol action and further suggest that differences in catalytic mechanisms affecting post-translational processing may account for some genetic differences in ethanol sensitivity of GABAA receptors.

Animals↗
PubMed1992

The only domain which distinguishes Epstein-Barr virus latent membrane protein 2A (LMP2A) from LMP2B is dispensable for lymphocyte infection and growth transformation in vitro; LMP2A is therefore nonessential.

Using second-site homologous recombination, Epstein-Barr virus (EBV) recombinants were constructed which carry an LMP2A mutation terminating translation at codon 19. Despite the absence of LMP2A or LMP2A cross-reactive protein, the recombinants were able to initiate and maintain primary B-lymphocyte growth transformation in vitro. EBNA1, EBNA2, and LMP1 expression was unaffected by the LMP2A mutation. The LMP2A mutant recombinant EBV-infected lymphoblastoid cell lines (LCLs) were identical to wild-type recombinant EBV-infected control LCLs with respect to initial outgrowth, subsequent growth, sensitivity to limiting cell dilution, sensitivity to low serum, and growth in soft agarose. The permissivity of LCLs for lytic EBV infection and virus replication was also unaffected by the LMP2A mutation.

Antigens, Viral↗
PubMed1992

An activation-dependent, T-lymphocyte-specific transcriptional activator in the mouse mammary tumor virus env gene.

Transcription of the complete mouse mammary tumor virus (MMTV) proviral genome in mouse cells is controlled by a strong promoter in its long terminal repeat. In the mouse T lymphoma EL4, there is a second, activation-dependent transcriptional initiation site within the envelope (env) gene, from which a short mRNA is generated, encoding the open reading frame of the long terminal repeat. We now report the isolation of a segment of the MMTV env gene (called META, for MMTV env transcriptional activator) which has the expected transcription-activating properties seen in EL4.E1 cells. Namely, it induces activation-dependent, T-lymphocyte-specific transcription of a chloramphenicol acetyltransferase reporter gene. It is active in mouse or human T-helper lymphocyte lines when they are stimulated to transcribe lymphokine genes but is inactive in unstimulated T-helper cells, fibroblasts, a cytotoxic T-lymphocyte line, and a mastocytoma cell line. Its activity is inhibited by cyclosporin A, a specific inhibitor of lymphokine transcription. Several forms of the META have been isolated from EL4.E1 cells, a mouse T-helper cell hybridoma, and from BALB/c spleen cells. Linked to the heterologous thymidine kinase promoter, a 400-bp portion of it is an inducible, orientation-independent, and cyclosporin A-sensitive transcriptional activator in T-helper cells.

Animals↗
PubMed1991

Voluntary antenatal HIV testing--results of a pilot study.

Voluntary testing for antibody to human immunodeficiency virus (HIV) was offered to 4929 antenatal patients attending two hospitals in South Manchester during a 12 month period in 1989/90 in order to assess the feasibility of obtaining seroprevalence data by this method. Of these patients, 1728 (35%) agreed to a named test, 1396 (28%) to an unlinked anonymous test and the remaining 37% declined to be tested. The proportion of women tested increased from 22% to 88% over the period, and was similar in those with and without an identified risk factor for infection. One HIV antibody positive patient was found; she was tested anonymously and had no identified risk. The substantial cost in time and money required to establish the universal voluntary testing programme and the incomplete patient compliance confirm the importance of the unlinked anonymous surveys currently being established in the UK to monitor seroprevalence in sentinel populations.

AIDS Serodiagnosis↗