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Biomedical subjects

A Graham

Publications and source records attributed to A Graham.

At least 217 records · Page 12Linked to original sources
PubMed1989

Image understanding system for histopathology.

An image understanding machine vision system for histological diagnoses is based on three interacting expert systems: a diagnostic expert system utilizing terms familiar to pathologists, an interpretive expert system relating human diagnostic concepts to computable histometric features and a scene segmentation expert system which extracts the diagnostic information from the imagery. The control software for the image understanding system resides on a multiprocessor computer. This article details measures to maintain system efficiency and to accommodate the requirements of interprocess communication and processing task scheduling.

Diagnosis, Computer-Assisted↗
PubMed1988

Diagnosis of alpha 1-antitrypsin deficiency by enzymatic amplification of human genomic DNA and direct sequencing of polymerase chain reaction products.

We have compared sequencing of cloned "polymerase chain reaction" (PCR) products and the direct sequencing of PCR products in the examination of individuals from six families affected with alpha 1-antitrypsin (AAT) deficiency. In families where paternity was in question we confirmed consanguinity by DNA fingerprinting using a panel of locus-specific minisatellite probes. We demonstrate that direct sequencing of PCR amplification products is the method of choice for the absolutely specific diagnosis of AAT deficiency and can distinguish normals, heterozygotes and homozygotes in a single, rapid and facile assay. Furthermore, we demonstrate the reproducibility of the PCR and a rapid DNA isolation procedure. We have also shown that two loci can be simultaneously amplified and that the PCR product from each locus can be independently examined by direct DNA sequencing.

Base Sequence↗
PubMed1988

Factors regulating the secretion of lysophosphatidylcholine by rat hepatocytes compared with the synthesis and secretion of phosphatidylcholine and triacylglycerol. Effects of albumin, cycloheximide, verapamil, EGTA and chlorpromazine.

1. The synthesis and secretion of glycerolipid by monolayer cultures of rat hepatocytes was measured by determining the incorporations of [3H]glycerol, [3H]oleate and [14C]choline and by the absolute concentration of triacylglycerol. 2. The presence of albumin in the medium stimulated the accumulation of lysophosphatidylcholine in the medium by 11-13-fold. 3. Cycloheximide did not significantly alter the accumulation of lysophosphatidylcholine. 4. This process was particularly sensitive to inhibition by chlorpromazine and verapamil, compared with the secretion of triacylglycerol and phosphatidylcholine. By contrast, it was relatively less sensitive to EGTA. 5. It is suggested that intracellular Ca2+ may be important in the production of lysophosphatidylcholine, which then accumulates in the medium by binding to albumin. In vivo this lysophosphatidycholine may be a means of delivering choline and polyunsaturated fatty acids to other organs.

Albumins↗
PubMed1988

Fatty acid specificity for the synthesis of triacylglycerol and phosphatidylcholine and for the secretion of very-low-density lipoproteins and lysophosphatidylcholine by cultures of rat hepatocytes.

1. The synthesis and secretion of glycerolipids by monolayer cultures of rat hepatocytes was measured by using radioactive choline, glycerol and fatty acids and by measuring the concentration of triacylglycerols in the cells. 2. The incorporation of glycerol into triacylglycerol and the accumulation of this lipid in hepatocytes showed little specificity for fatty acids, except for eicosapentaenoate, which stimulated least. Oleate was more effective at stimulating triacylglycerol secretion than were palmitate, stearate, arachidonate and eicosapentaenoate. 3. Linoleate, linolenate, arachidonate and eicosapentaenoate stimulated the incorporation of glycerol and choline into phosphatidylcholine that was secreted into the medium. By contrast, palmitate and stearate produced relatively high incorporations into the phosphatidylcholine that remained in the cells. 4. The incorporation of glycerol and choline into lysophosphatidylcholine in the medium was stimulated 2-3-fold by all of the unsaturated fatty acids tested, whereas palmitate and stearate failed to stimulate if the acids were added separately. When 1 mM-stearate was added with 1 mM-linoleate, the incorporation of linoleate into lysophosphatidylcholine was about 4 times higher than that of stearate. 5. It is proposed that the secretion of lysophosphatidylcholine by the liver could provide a transport system for choline and essential unsaturated fatty acids to other organs.

Animals↗
PubMed1988

Bilateral Warthin's tumor.

A case report of bilateral mixed Warthin's tumors with nonuniform uptake demonstrated by Tc-99m pertechnetate imaging is presented. The findings are compared to CT, surgical, and pathology results.

Adenolymphoma↗
PubMed1988

Characterization of a murine homeo box gene, Hox-2.6, related to the Drosophila Deformed gene.

The Hox-2 locus on chromosome 11 represents one of the major clusters of homeo-box-containing genes in the mouse. We have identified two new members (Hox-2.6 and Hox-2.7), which form part of this cluster of seven linked genes, and it appears that the Hox-2 locus is related by duplication and divergence to at least one other mouse homeo box cluster, Hox-1. The Hox-2.6 gene encodes a predicted protein of 250 amino acids, which displays extensive similarity in multiple regions to certain mouse, human, Xenopus, and zebra fish homeo domain proteins. The Drosophila Deformed (Dfd) gene also shares these same regions of similarity, and based on this sequence conservation, we suggest that Hox-2.6 forms part of a vertebrate 'Dfd-like' family. Hox-2.6 is expressed in fetal and adult tissues and is modulated during the differentiation of F9 teratocarcinoma stem cells. In situ hybridization analysis of mouse embryos shows that the Hox-2.6 is expressed in ectodermal derivatives: spinal cord, hindbrain, dorsal root ganglia, and the Xth cranial ganglia. In the central nervous system, expression is observed in the most posterior parts of the spinal cord, with the anterior limit residing in a region of the hindbrain and no expression in the mid- or forebrain. In mesodermal structures, Hox-2.6 is expressed in the kidney, the mesenchyme of the stomach and lung, and the longitudinal muscle layer of the gut. Expression has not been observed in derivatives of embryonic endoderm. The patterns of Hox-2.6 expression in both mesoderm and ectoderm are spatially restricted and may reflect a role for the gene in the response to or establishment of positional cues in the embryo.

Amino Acid Sequence↗
PubMed1988

An angiographic study of ischemia as a determinant of neovascularization in arteriovenous reversal.

The results of recent studies by ourselves and others have demonstrated the feasibility of revascularizing severely ischemic limbs by means of staged arteriovenous reversal at the popliteal level. The results of investigations we did, both clinically and in an animal model, revealed the development of an intense vascular network in the region of the arteriovenous anastomosis as an important component of the revascularization process. To determine the role of ischemia in this process, four groups consisting of three dogs each underwent a popliteal artery to vein anastomosis. In group I, there was no ischemia; group II, distal ischemia only; group III, partial ischemia, and group IV, total ischemia. Angiography at four weeks in all dogs demonstrated that the intense neovascular network seen in previous studies developed only in the limbs of the dogs in group IV. We conclude that the neovascular process seen after creation of arteriovenous reversal develops as a response to severe ischemia. Further studies are needed to better characterize the nature of these vessels, and it is our hope that, in doing so, means of enhancing development of these vessels in order to indirectly revascularize otherwise unsalvagable extremities will be realized.

Animals↗
PubMed1987

Reassortment of human rotavirus possessing genome rearrangements with bovine rotavirus: evidence for host cell selection.

Mixed infections of secondary rhesus monkey kidney cells with human rotaviruses carrying rearranged genomes and with bovine rotavirus yielded a high percentage of reassortants. The genotypes of 511 plaque-purified clones raised in either MA104 or BSC-1 cells have been determined and the frequencies of different genotypes have been calculated. It was found that reassortants did not emerge at random; there was non-random association of certain genes; the cell line used to isolate reassortants influenced the result, i.e. host cell factors had a selective effect on a recombinational mixture.

Animals↗
PubMed1987

Herpes simplex virus type 2 glycoprotein biogenesis: effect of monensin on glycoprotein maturation, intracellular transport and virus infectivity.

The ionophore monensin inhibited the formation of herpes simplex virus type 2 (HSV-2) particles by about 30% but the yields of infectious particles were reduced to 5% and 1% for cell-associated and extracellular virus, respectively. The presence of monensin did not affect the processing of the two viral glycoproteins gB-2 and gG-2. However, two other glycoproteins, gC-2 and gD-2, were not processed to their fully mature forms in the monensin-treated cells and only the faster moving pgC-2 and pgD-2 were detected. The cell-associated virus particles contained the glycoproteins gB-2, gC-2, gD-2 and gG-2, whereas the extracellular virus particles contained only gG-2 glycoprotein. These results suggest that HSV-2 particles containing all the viral glycoproteins are transported via the Golgi apparatus to the cell surface but that virus particles containing only gG-2 may follow a different pathway for transport and release.

Animals↗
PubMed1986

Inhibition of human and rat lipoprotein lipase by high-density lipoprotein.

The hydrolysis in vitro of preactivated Intralipid (an artificial triacylglycerol-phospholipid emulsion) by rat adipose tissue lipoprotein lipase is inhibited by rat high-density lipoprotein (HDL). The aim of this work was to investigate whether human lipoprotein lipase was also inhibited, the mechanism of inhibition of the rat enzyme by HDL, and the role of the various individual apolipoproteins. Both human and rat lipoprotein lipase from post-heparin plasma are inhibited by HDL. This inhibition is considerably decreased if the HDL is first made 'apolipoprotein poor' by removal of some transferable apolipoproteins. In contrast, both native and apolipoprotein poor HDL inhibit the hydrolysis of Intralipid by rat hepatic lipase. Apolipoproteins C and E, either free in solution or attached to lipid vesicles, inhibit the hydrolysis of activated Intralipid by rat lipoprotein lipase to a maximum of 85% and 50%, respectively. Apolipoprotein A attached to vesicles gives little inhibition. HDL apolipoprotein and apolipoprotein C compete with the substrate for binding to lipoprotein lipase with apolipoprotein C having a higher affinity for the enzyme than HDL apolipoprotein. The inhibition of lipoprotein lipase by HDL can be explained by the association of the constituent apolipoproteins, in particular apolipoprotein C, with the enzyme so that there is less enzyme available to act on substrate.

Animals↗
PubMed1986

Biliary excretion of aluminum in aluminum osteodystrophy with liver disease.

Two patients with chronic liver disease developed elevated serum aluminum concentrations and biopsy-proven osteodystrophy. Neither patient had chronic renal failure but both had received aluminum-containing antacids for long periods. We measured biliary and urinary aluminum excretion during antacid loading in patients with normal liver function. Our studies show that biliary excretion is an important route of elimination of orally absorbed aluminum, and we suggest that long-term antacid therapy in patients with severe liver disease be monitored with periodic serum and urinary aluminum determinations to avoid aluminum osteodystrophy.

Adult↗