Biomedical subjects

S A Richmond

Publications and source records attributed to S A Richmond.

7 recordsLinked to original sources

PubMed2002

Robust and sensitive nylon hybridization membrane suitable for high-throughput robotic arraying applications.

An important aspect of automated macroarraying is the suitability of the nylon membrane selected on which samples are to be arrayed. PerForma is a positively charged nylon membrane that has been developed specificallyfor automated macroarraying. Tests usingfluorescent hybridization detection methods have shown that immobilized DNA amounts as low as 0.25 pg can be detected and that positive signals are obtainable after 21 stripping cycles. This report describes the improved colony growth, improved handling characteristics, increased hybridization detection sensitivity, and increased stripping and reprobing capability obtained using PerForma.

Cells, Cultured↗

PubMed2001

Assessment of natural attenuation of chlorinated aliphatics and BTEX in subarctic groundwater.

We examined biogeochemistry and microbiology associated with natural attenuation of trichloroethene (TCE), trichloroethane (TCA), and benzene in a subarctic aquifer. Identification of a predominant terminal electron-accepting process (TEAP) and characterization of typical natural attenuation footprints was difficult. Hydrogen and ferrous iron concentrations suggested that iron reduction was the predominant TEAP; calculated in situ Gibbs free energies for iron reduction were energetically feasible at all wells although a source of ferric iron has not been conclusively determined. The presence of dissolved sulfide and favorable free energies for sulfate reduction provided support of concurrent iron and sulfate reduction. Methanogenesis from H2/CO2 was generally not energetically favorable. The presence of TCE and TCA degradation intermediates suggested that biological reductive dechlorination occurred, although proportions of intermediates relative to parent compounds remained stable. By September 2000, contaminant concentrations were within regulatory standards at most sampling points. However, low rates of microbial activity and incomplete degradation imply that intrinsic bioremediation did not likely represent an important contribution to contaminant removal atthis site, where dilution appeared to be the primary attenuation mechanism.

Biodegradation, Environmental↗

PubMed2001

Effects of chitin on microbial emulsification, mineralization potential, and toxicity of bunker C fuel oil.

Bunker C, one of the most frequently spilled petroleum products in the US, is difficult to remove from oiled surfaces and is relatively recalcitrant to biodegradation; therefore, emulsification and biodegradability must be optimized before bioremediation can be considered a viable treatment option. Sand from a freshly oiled beach near Dutch Harbor, Alaska, was incubated at 10 degrees C with nutrients (Bushnell-Haas (BH)) or nutrients with crab shell chitin (BH-C). BH-C amendment resulted in greater numbers of bunker C emulsifiers and greater mineralization potentials for hexadecane, phenanthrene, and fluorene than with BH only. Compared to BH alone, mineralization potentials for bunker C also were higher in BH-C, with an estimated 8% of fuel oil mineralized after 6 weeks. Microbially emulsified oil was more toxic than in uninoculated controls (p < 0.05) as measured by Microtox assays. However, toxicity was significantly lower in BH-C than BH after 4 and 6 weeks incubation (p < 0.05).

Animals↗

PubMed1996

Localization of the glutamate receptor subunit GluR1 on the surface of living and within cultured hippocampal neurons.

The distribution of the glutamate receptor subunit GluR1 was investigated in cultured hippocampal neurons by confocal microscopy, using polyclonal antibodies directed against either the N- or C-terminal region. On living neurons, GluR1 immunofluorescence was detected with the N-terminal antibody only. GluR1 was localized in a highly punctate manner on the surface of neuronal soma and throughout the dendritic tree. Many GluR1 puncta co-localized with the synaptic marker synaptophysin, although extrasynaptic GluR1 puncta were also observed. A comparison of GluR1 subunit distribution of living neurons labelled with N-terminal antibody with that obtained after the cells had been fixed, permeabilized and subsequently reacted with C-terminal or additional N-terminal antibody showed a number of differences. In permeabilized cells additional, diffuse labelling was observed which was very pronounced in the soma and extended into the proximal dendrites. Furthermore, some spines showed little or no labelling of their membrane surface, but labelled strongly after the cells had been fixed and permeabilized. Such spines may be the postsynaptic components of silent or suboptimal synapses.

Animals↗

PubMed1993

Biochemical and immunocytochemical characterization of antipeptide antibodies to a cloned GluR1 glutamate receptor subunit: cellular and subcellular distribution in the rat forebrain.

Antibodies were made to synthetic peptides corresponding to residues 253-367, 757-771 and 877-889 of the published amino acid sequence of the rat brain glutamate receptor GluR1 subunit [Hollmann et al. (1989) Nature 342, 643-648]. The peptides were synthesized both as multiple copies on a branching lysyl matrix (multiple antigenic peptides) and conventional linear peptides using solid-phase synthesis. Rabbits were immunized with these peptides either without conjugation (multiple antigenic peptides) or following coupling to ovalbumin with glutaraldehyde (monomeric peptides). The antibodies from immune sera were then purified by affinity chromatography using reactigel coupled monomeric peptides. All the rabbits produced good antipeptide responses, and were characterized by immunoprecipitation of solubilized alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and kainate binding activity and by their staining patterns on immunoblots. Antibody to peptide 253-267 specifically immunoprecipitated 12 +/- 3, 50 +/- 3 and 44 +/- 4% of solubilized alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate binding activity from cortex, hippocampus and cerebellum, respectively. Under identical conditions, antibody against the 877-889 peptide removed 23 +/- 4, 9 +/- 4 and 15 +/- 9% of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate binding sites from these areas. On immunoblots of rat brain membrane samples separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, antibodies labelled a 105,000 mol. wt immunoreactive band. GluR1 was immunoaffinity-purified using subunit-specific antibodies against both N-terminal (253-267) and C-terminal (877-889) residues, covalently attached to protein A-agarose. Analysis of the purified product from each column showed a major immunoreactive band, recognized by both sera at 105,000 mol. wt and silver staining identified the same major protein. After exhaustive immunoprecipitation of solubilized membrane samples with antibody against the C-terminal of the subunit, a subpopulation of GluR1 was labelled with antibodies specific for the N-terminal part of the receptor. These observations suggest that the GluR1 subunit consists of at least two isoforms possessing a common N-terminal region but a distinct C-terminus. Immunocytochemistry, using immunoperoxidase staining, was performed for the GluR1 subunit in rat forebrain with antisera raised against the N-terminal (253-267) and the C-terminal parts (877-889) of the molecule. Both antisera gave a similar distribution of immunoreactivity at the light-microscopic level. Immunoreactivity for the GluR1 subunit was selectively distributed throughout the rat forebrain. The hippocampus, septum, amygdala and olfactory bulb exhibited the strongest immunoreactivity.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1989

Inhibition of cisplatin-induced emesis in the pigeon by a non-psychotropic synthetic cannabinoid.

The (+) enantiomer of the synthetic cannabinoid, 7-hydroxy-delta-6-tetrahydrocannabinol, dimethylheptyl homolog (HU-211), possesses significant antimetic efficacy in the pigeon. However, unlike all anti-emetic cannabinoids tested in the past, it is devoid of psychotropic (cannabimimetic) activity. The anti-emetic activity of HU-211 was determined in pigeons given 10 mg/kg i.v. cisplatin, a widely used antitumour agent, which is also a potent emetogenic agent at this dose. This activity was compared with that of delta-1-tetrahydrocannabinol (delta-1-THC). HU-211 pretreatment elicited a dose-related inhibition of cisplatin vomiting, with the optimal dose of HU-211 (2.5 mg/kg) inhibiting emesis by nearly 90%. Delta-1-THC in doses up to 5 mg/kg caused only an insignificant reduction in vomiting. The activity was increased in the presence of cupric chloride (0.8 mg/kg). The optimal dose of delta-1-THC (5.0 mg/kg) with CuCl2 very significantly diminished the total amount of vomitus expelled (up to 90%). However, it failed to inhibit emesis in 50% of all animals tested, did not significantly affect the time of onset of emesis and was highly psychotropic. The optimal dose of HU-211 (2.5 mg/kg) with CuCl2 inhibited emesis by 97%, significantly delayed the time on onset of emesis in the very few animals that did vomit and was completely non-psychotropic. The curve for the antiemetic effect of HU-211 was U-shaped over a narrow dose range. The present report demonstrates that complete separation of psychotropic and antiemetic activities is possible in the cannabinoid series.

Animals↗

PubMed1989

Nonpsychotropic cannabinoid acts as a functional N-methyl-D-aspartate receptor blocker.

Binding studies using the enantiomers of the synthetic cannabinoid 7-hydroxy-delta 6-tetrahydrocannabinol 1,1-dimethylheptyl homolog in preparations of rat brain cortical membranes reveal that the (+)-(3S,4S) enantiomer HU-211 blocks N-methyl-D-aspartate (NMDA) receptors in a stereospecific manner and that the interaction occurs at binding sites distinct from those of other noncompetitive NMDA antagonists or of glutamate and glycine. Moreover, HU-211 induces stereotype and locomotor hyperactivity in mice and tachycardia in rat, effects typically caused by NMDA receptor antagonists. HU-211 is also a potent blocker of NMDA-induced tremor, seizures, and lethality in mice. This compound may therefore prove useful as a nonpsychoactive drug that protects against NMDA-receptor-mediated neurotoxicity.

Animals↗