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Biomedical subjects

A R Long

Publications and source records attributed to A R Long.

At least 19 recordsLinked to original sources
PubMed1998

Isolation and characterisation of smallminded, a Drosophila gene encoding a new member of the Cdc48p/VCP subfamily of AAA proteins.

Smallminded (smid) encodes a new member of the cdc48p/VCP subfamily of AAA proteins in Drosophila. The gene was isolated by plasmid rescue from a GAL4 enhancer trap line which shows reporter gene expression in neuroblasts, imaginal disks and a subset of sensory neurons. Larvae homozygous for the insert arrest development as second instar larvae and die without pupating. The most obvious defect in these larvae is a significantly reduced CNS, hence the naming of the gene as smallminded. The deduced amino acid sequence of smid contains a tandem duplication of the AAA nucleotide binding domain characteristic of the cdc48p/VCP subfamily. Overall, smid shares 33% identical residues with its closest relative, yeast L0919-chrXII and 26-29% with other members of the cdc48p/VCP subfamily. The most highly conserved regions of the predicted protein structure are found in and around the nucleotide binding domains. The gene is expressed at all developmental stages.

Amino Acid Sequence↗
PubMed1998

Dynamic developmental expression of smallminded, a Drosophila gene required for cell division.

Here we describe the expression pattern of the smallminded (smid) gene during Drosophila development and investigate the phenotype of a null mutant. In situ hybridisation reveals the ubiquitous expression of smid transcript throughout early embryonic stages until the extended germ band stage, after which expression becomes localised to the neurogenic ectoderm and gonad. Post-embryonic expression is restricted to tissues engaged in the developmental programme of the adult fly: the re-enlarged neuroblasts; imaginal disks; histoblast nests; and precursors of adult muscles. The correlation of smid expression with mitotic activity suggests a cell cycle function which is confirmed by the observed phenotype of a smid null mutant characterised by an abnormally small CNS, due to defective mitosis of post-embryonic neuroblasts and their subsequent death by apoptosis.

Animals↗
PubMed1995

Particle beam liquid chromatography-mass spectrometry of triphenylmethane dyes: application to confirmation of malachite green in incurred catfish tissue.

Eight triphenylmethane dyes (malachite green, leucomalachite green, gentian violet, leucogentian violet, brilliant green, pentamethyl gentian violet, N',N'-tetramethyl gentian violet and N',N"-tetramethyl gentian violet) have been characterized by particle beam liquid chromatography-mass spectrometry. The electron ionization spectra obtained of these dyes by this technique exhibit similar fragmentation, with the formation of phenyl and substituted phenyl radicals, and loss of alkyl groups from the amines. It was observed that the six cationic dyes are reduced in the mass spectrometer source to form the corresponding leuco compounds. This technique was evaluated for the confirmation of malachite green and leucomalachite green in incurred catfish (Ictalurus punctatus) muscle tissue.

Animals↗
PubMed1994

Optimization of the analytical performance of the magnetic sector mass spectrometer for the identification of residual chloramphenicol in shrimp.

Chemical noise limits mass spectrometric detection of chloramphenicol (CAP) with electron capture ionization at low resolution, and makes CAP identification at concentrations of 5 parts per billion (ppb) difficult. Increasing the resolution from 1000 to 3500, however, was sufficient to separate the analyte signals from the noise signals, and resulted in a 100 times higher analytical sensitivity. The introduction of sweep gas in the ion source decreased the scattering of the quantitative results on average by a factor of 7, and thereby improved the precision of the analyses to an acceptable level (CV < 10%). Under such conditions, CAP residues of 1.5 and 2.1 ppb in shrimp as determined by electron capture gas chromatography/mass spectrometry can readily be identified by monitoring four diagnostic ions.

Animals↗
PubMed1993

Disruption and fractionation of biological materials by matrix solid-phase dispersion.

The isolation of drug residues, environmental contaminants or naturally occurring component molecules from biological materials is often a complex undertaking. We report here the development and application of a simple approach to the disruption of biological samples that also allows for the rapid fractionation and isolation of the sample's natural components or incurred residues. This process, called matrix solid-phase dispersion (MSPD), combines the use of mechanical forces generated from the grinding of samples with irregular shaped particles (silica or polymer based solid supports) with the lipid solubilizing capacity of a support-bound polymer (octadecylsilyl or others) to produce a sample column material from which dispersed sample matrix components can be selectively isolated. The factors governing this process and examples of its various applications are presented.

Animals↗
PubMed1991

Lysis and fractionation of Mycobacterium paratuberculosis and Escherichia coli by matrix solid-phase dispersion.

A novel method for the lysis and subsequent fractionation of bacterial constituents from Mycobacterium paratuberculosis strain 19698 (M. paratuberculosis) and Escherichia coli strain DH5 alpha utilizing the technique of matrix solid-phase dispersion (MSPD) is described. Bacteria were blended with octadecylsilyl (C18) derivatized silica to obtain cellular lysis. The blended material was used to prepare a column which was sequentially eluted with solvents of increasing polarity. Fractionation of cellular components was confirmed by analysis of the solvent extracts. The possible applicability of the MSPD technique as a general method for the lysis and fractionation of bacterial components is proposed.

Bacteriological Techniques↗
PubMed1991

The periplasmic modifier protein for methanol dehydrogenase in the methylotrophs Methylophilus methylotrophus and Paracoccus denitrificans.

A modifier protein (M-protein), which increases the affinity of methanol dehydrogenase (MDH) for alcohols but decreases its affinity for formaldehyde, has been partially purified from Methylophilus methylotrophus and Paracoccus denitrificans. Analysis was complicated by non-protein factors in bacterial extracts that are able to mimic M-protein in one of its functions-that of increasing the activity of MDH with butane-1,3-diol in the dye-linked assay system. The 67 kDa polypeptide, previously identified as a subunit of the M-protein, is an unrelated cytoplasmic protein. The M-protein is exclusively periplasmic and is a multimeric protein with subunits of 45 kDa. The M-protein is active in the 'physiological' assay system with the specific cytochrome c electron acceptor for MDH, lowering its affinity for formaldehyde. It has its maximum effect when the ratio of M-protein:MDH is 1:5 but its concentration in the periplasm is much lower than 20% of that of MDH.

Alcohol Oxidoreductases↗
PubMed1990

Method for the isolation and liquid chromatographic determination of eight sulfonamides in milk.

A method for the isolation and liquid chromatographic determination of eight sulfonamides in milk is presented. Fortified or blank milk samples (0.5 ml) were blended with octadecylsilyl (C18T) derivatized silica (2 g). A column made from the sample C18T matrix was first washed with hexane (8 ml) following which the sulfonamides were eluted with methylene chloride (8 ml). The eluate contained sulfonamide analytes which were free from interferences when analyzed by high-performance liquid chromatography (HPLC) utilizing UV detection (270 nm, photodiode array). Standard curve correlation coefficients (range, 0.998 +/- 0.002 to 0.999 +/- 0.001), average percentage recoveries (73.1 +/- 7.4 to 93.7 +/- 2.7%), and the inter-(3.9-9.6%) and intra-assay (2.2-6.7%) variabilities, were determined for the concentration range examined (62.5-2000 ng/ml) and resulted in a minimal detectable limit of 1.25 ng on column (62.5 ng/ml, 20 microliters injection from a final sample volume of 0.5 ml). Savings in terms of time and solvent make this procedure attractive when compared to classical isolation techniques for sulfonamides.

Animals↗
PubMed1989

Isolation of drug residues from tissues by solid phase dispersion.

A new method based on solid phase dispersion of tissue for the subsequent isolation of drugs is reported. By blending tissues with a polymeric phase bound to a solid support one obtains a semi-dry material which can be used as a column packing material from which one can isolate drugs in a stepwise fashion based on the solubility characteristics of the drugs in this matrix. The applicability of this approach for multidrug residue extraction from a single sample is demonstrated for compounds representing the organophosphate, benzimidazole anthelmintic and beta-lactam antibiotic drug classes.

Animals↗
PubMed1987

The effect of metyrapone on cytokinin ([8-14C]benzylaminopurine) metabolism in mature green tomato pericarp.

Cytokinin, [8-14C]Benzylaminopurine, metabolism in tomato pericarp was followed during a 3 h period utilizing thin layer chromatography and visualization by fluorography. Fluorography indicated the formation of at least 7 metabolites during 3 h. Cytokinin metabolism was reduced by approximately 40% in 3 h by the presence of 250 microM metyrapone, an inhibitor of cytochrome P-450 related enzyme systems. In the presence of metyrapone, the number of radioactive metabolites on the thin layer plate was reduced from 7 to 4 and 2 of these were unique to the metyrapone-treated sample. These data suggest the initial step in benzylaminopurine metabolism in tomato pericarp may be mediated by a cytochrome P-450 related enzyme system which is altered in the presence of metyrapone.

Adenine↗
PubMed1985

Hydatidiform mole in Victoria: aetiology and natural history.

A retrospective study was made of 455 patients referred to the Hydatidiform Mole Register of the Royal Women's Hospital from 1973-1982 who fulfilled the criteria for diagnosis of hydatidiform mole. The incidence of hydatidiform mole was 1:1,357 livebirths in Victoria. Age greater than 40 years (P less than 0.001), nulliparity (P less than 0.005) and parity greater than 4 (P less than 0.001) were the only predisposing factors found. An association with artificial insemination with donor semen was also noted (P less than 0.025). The need for further treatment for persistent trophoblastic activity (13.6% of patients) was independent of the method of evacuation employed and of gestation at evacuation. Only 2 cases of histologically proven postmolar choriocarcinoma occurred, one of which was also the only death recorded from all patients registered following a molar pregnancy.

Adult↗
PubMed1985

Malignant sequelae of molar pregnancy in Victoria.

In a retrospective study of 455 patients with confirmed molar pregnancy, registered with the Hydatidiform Mole Register of the State of Victoria in the years 1973-1982 inclusive, treatment for persistent trophoblastic activity was necessary in 62 (13.6%) patients. The need for treatment was independent of levels of urinary chorionic gonadotrophin (UCG) excretion prior to evacuation of the molar pregnancy, age, parity or blood group. All patients achieved initial remission of UCG levels within 5 courses of treatment. Risk factors were scored retrospectively and patients responded poorly if therapy inappropriate to risk factors was given. Only 2 cases of histologically proven choriocarcinoma occurred and the only death recorded was in 1 of these patients.

Adult↗
PubMed1980

Choriocarcinoma coexistent with intrauterine pregnancy.

Two cases of choriocarcinoma coexisting with intrauterine pregnancy are presented. The literature on 28 previously reported cases is reviewed with reference to mode of presentation, maternal survival and pathogenesis.

Adult↗
PubMedDate not supplied

A liquid chromatographic method for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food using matrix solid-phase dispersion in conjunction with a zero reference material as a method development tool.

A liquid chromatographic method is described for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted from medical food without saponification by matrix solid-phase dispersion and chromatographed by normal-phase chromatography with fluorescence detection. Retinyl palmitate and all-rac-alpha-tocopheryl acetate are quantitated isocratically with a mobile phase of 0.125% (v/v) and 0.5% (v/v) isopropyl alcohol in hexane, respectively. Results compared favorably with label declarations on retail medical foods. Recoveries determined on an analyte-fortified zero reference material for a milk-based medical food averaged 98.3% (n = 25) for retinyl palmitate spikes and 95.7% (n = 25) for all-rac-alpha-tocopheryl acetate spikes. Five concentrations were examined for each analyte, and results were linear (r2 = 0.995 for retinyl palmitate and 0.9998 for all-rac-alpha-tocopheryl acetate) over the concentration range examined, with coefficients of variation in the range 0.81-4.22%. The method provides a rapid, specific, and easily controlled assay for analysis of retinyl palmitate and all-rac-alpha-tocopheryl acetate in fortified medical foods.

Chromatography, Liquid↗
PubMedDate not supplied

Analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical foods using a zero control reference material (ZRM) as a method development tool.

A liquid chromatographic method is described for analysis of all- rac-alpha-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted in isopropyl alcohol and hexane-ethyl acetate without saponification and quantitated by normal-phase chromatography with fluorescence detection. All rac-alpha-tocopheryl acetate and retinyl palmitate are chromatographed isocratically with a mobile phase of 0.5% (v/v) and 0.125% (v/v) isopropyl alcohol in hexane, respectively. Recovery studies performed on a medical food zero control reference material (ZRM) fortified with the analytes averaged 99.7% (n = 25) for retinyl palmitate and 101% (n = 25) for all- rac-alpha-tocopheryl acetate. Coefficients of variation were 0.87-2.63% for retinyl palmitate and 1.42-3.20% for all-rac-alpha-tocopheryl acetate. The method provides a rapid, specific, and easily controlled assay for analysis of vitamin A and vitamin E in medical foods. Use of chlorinated solvents is avoided.

Chromatography↗