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Biomedical subjects

J Marshall

Publications and source records attributed to J Marshall.

At least 307 records · Page 17Linked to original sources
PubMed1991

Granulocyte/macrophage colony-stimulating factor (GM-CSF) gene expression by eosinophils in nasal polyposis.

Nasal polyposis is a chronic inflammatory condition of the upper airways characterized by infiltration of activated inflammatory cells, particularly eosinophils. Granulocyte/macrophage colony-stimulating factor (GM-CSF) is a cytokine with powerful biologic effects including the regulation of survival, proliferation, and activation of granulocytes as well as differentiation of hemopoietic cells. To examine the potential role of GM-CSF in the pathogenesis of this condition, we investigated gene expression and production of GM-CSF in nasal polyp tissues as well as in the normal nasal mucosa. Immunoreactive GM-CSF was detected by enzyme-linked immunosorbent assay in the 24-h supernatant of nasal polyp tissues placed in culture. By Northern blot analysis and Southern blot analysis following a reverse-transcription polymerase chain reaction using a human GM-CSF cDNA probe, we detected GM-CSF mRNA in nasal polyp tissues, as well as in the tissue from a patient with allergic rhinitis, but not in the normal nasal mucosa. By in situ hybridization using the same probe, cells expressing mRNA specific for GM-CSF were observed in nasal polyp tissues and in the allergic nasal mucosa. In addition, by the combination of in situ hybridization and counterstaining with chromotrope 2R, we demonstrated that approximately 30% of eosinophils infiltrating the polyp tissue express the GM-CSF gene. These results suggest a novel mechanism by which eosinophils may contribute to the pathogenesis of chronic inflammatory diseases such as nasal polyposis, allergic rhinitis, and, by implication, asthma.

Base Sequence↗
PubMed1991

Temporal variations in the ionic transport across rabbit retinal pigment epithelium.

The potential difference (PD), short circuit current (SCC) and resistance (R) of rabbit retina-retinal pigment epithelium-choroid-sclera preparations were measured in a modified Ussing chamber. The rabbits were kept in 14 hour light/10 hour dark cycle conditions for 14 days: tissues were taken for measurement at 1.5, 6, 13, 20 and 23 hours after the start of the fifteenth light period. Significant variations in PD and SCC were observed 6 hours into the light cycle while the resistance remained constant during the test period. When in a second experiment the fifteenth light period was replaced by darkness, the highest PD and SCC values recorded occurred 12 hours after the time when the light period should have started in the normal light/dark cycle. In a third experiment the fifteenth light period was replaced by darkness and the retina was removed. There were variations in the PD and SCC as in the second experiment but the SCC peak was reduced in amplitude. From these preliminary studies it is suggested that these variations may be circadian in origin and may be related to variations in retinal function.

Animals↗
PubMed1991

Monoclonal antibody specific for BK virus large-T antigen allows discrimination among the different papovaviral large-T antigens.

The human papovaviruses BK virus (BKV) and JC virus (JCV) both encode a large-tumor (T) antigen which are highly homologous to each other as well as to simian virus 40 (SV40) large-T antigen. This high conservation of amino acid sequence has resulted in overlapping antigenicity such that immunological differentiation of the large-T antigens from the three different viruses has been difficult. Here we describe the generation and characterization of a new monoclonal antibody (BK-T.1) which is specific for BKV large-T antigen and which does not cross-react with the other papovaviral T antigens. We show that when BK-T.1 is used in conjunction with preexisting monoclonal antibodies against SV40 large-T antigen, it is possible to identify the origin of papovavirus T antigens.

3T3 Cells↗
PubMed1990

Defective intracellular transport and processing of CFTR is the molecular basis of most cystic fibrosis.

The gene associated with cystic fibrosis (CF) encodes a membrane-associated, N-linked glycoprotein called CFTR. Mutations were introduced into CFTR at residues known to be altered in CF chromosomes and in residues believed to play a role in its function. Examination of the various mutant proteins in COS-7 cells indicated that mature, fully glycosylated CFTR was absent from cells containing delta F508, delta 1507, K464M, F508R, and S5491 cDNA plasmids. Instead, an incompletely glycosylated version of the protein was detected. We propose that the mutant versions of CFTR are recognized as abnormal and remain incompletely processed in the endoplasmic reticulum where they are subsequently degraded. Since mutations with this phenotype represent at least 70% of known CF chromosomes, we argue that the molecular basis of most cystic fibrosis is the absence of mature CFTR at the correct cellular location.

Animals↗
PubMed1990

Expression and characterization of the cystic fibrosis transmembrane conductance regulator.

Cystic fibrosis (CF) is a common lethal genetic disease that manifests itself in airway and other epithelial cells as defective chloride ion absorption and secretion, resulting at least in part from a defect in a cyclic AMP-regulated, outwardly-rectifying Cl- channel in the apical surface. The gene responsible for CF has been identified and predicted to encode a membrane protein termed the CF transmembrane conductance regulator (CFTR). Identification of a cryptic bacterial promoter within the CFTR coding sequence led us to construct a complementary DNA in a low-copy-number plasmid, thereby avoiding the deleterious effects of CFTR expression on Escherischia coli. We have used this cDNA to express CFTR in vitro and in vivo. Here we demonstrate that CFTR is a membrane-associated glycoprotein that can be phosporylated in vitro by cAMP-dependent protein kinase. Polyclonal and monoclonal antibodies directed against distinct domains of the protein immunoprecipitated recombinant CFTR as well as the endogenous CFTR in nonrecombinant T84 cells. Partial proteolysis fingerprinting showed that the recombinant and non-recombinant proteins are indistinguishable. These data, which establish several characteristics of the protein responsible for CF, will now enable CFTR function to be studied and will provide a basis for diagnosis and therapy.

Chloramphenicol O-Acetyltransferase↗
PubMed1990

Microbial infection and the septic response in critical surgical illness. Sepsis, not infection, determines outcome.

The differential roles of infection as a microbial phenomenon and sepsis as a host response were studied in 210 critically ill surgical patients. Infections occurred in 41.4% of all cases and in 82% of nonsurviving patients. Both infection and the expression of a septic response, measured as a sepsis score, were associated with significantly increased intensive care unit morbidity and mortality. Nonsurviving patients with infection had significantly higher sepsis scores than did survivors. Nonsurvivors with sepsis, on the other hand, did not differ from survivors with respect to any variable reflecting infection but did have higher mean sepsis scores. Maximum sepsis scores and sepsis scores on the day of death were similar in patients dying without infection and those dying with uncontrolled infection. The magnitude of the host septic response, independent of the presence, bacteriologic characteristics, or control of infection, is an important determinant of outcome in critical surgical illness.

Bacterial Infections↗
PubMed1990

Complete atrioventricular block during cardiac catheterization: two cases reports in patients without pre-existing conduction abnormalities.

Third-degree atrioventricular block has been well documented during ventricular catheterization of patients with underlying conduction abnormalities. Two cases reported here describe patients with normal conduction at baseline who sustained complete heart block during ventricular catheterization. Catheterizing physicians should be aware of this risk, which has not been previously reported.

Cardiac Catheterization↗
PubMed1990

Sequence and functional expression of a single alpha subunit of an insect nicotinic acetylcholine receptor.

We report the isolation and sequence of a cDNA clone that encodes a locust (Schistocerca gregaria) nervous system nicotinic acetylcholine receptor (AChR) subunit (alpha L1). The calculated molecular weight of the unglycosylated polypeptide, which contains in the proposed extracellular domain two adjacent cysteine residues which are characteristic of alpha (ligand binding) subunits, is 60,641 daltons. Injection into Xenopus oocytes, of RNA synthesized from this clone in vitro, results in expression of functional nicotinic receptors in the oocyte membrane. In these, nicotine opens a cation channel; the receptors are blocked by both alpha-bungarotoxin (alpha-Bgt) and kappa-bungarotoxin (kappa-Bgt). Reversible block of the expressed insect AChR by mecamylamine, d-tubocurarine, tetraethylammonium, bicuculline and strychnine has also been observed. These data are entirely consistent with previously reported electrophysiological studies on in vivo insect nicotinic receptors and also with biochemical studies on an alpha-Bgt affinity purified locust AChR. Thus, a functional receptor exhibiting the characteristic pharmacology of an in vivo insect nicotinic AChR can be expressed in Xenopus oocytes by injection with a single subunit RNA.

Amino Acid Sequence↗
PubMed1990

Electrophysiologic characteristics of human and rat retinas in vitro.

To promote studies on the human retina, we investigated the survival of function in postmortem specimens. Visual pigment has been regenerated in normal human retinas, 5 to 58 hours postmortem, by exposure to retinal isomers in the dark. Levels from 0.1 to 0.41 nmol/mg protein were reached. Photoresponses were obtained in 9 of 13 retinas: P III maximum amplitudes ranged from 20-398 microV and thresholds, taking the criterion amplitude as 3 microV, ranged from 8.8-1340 quanta/micros2. In three cases, the b-wave was also seen. The P III amplitude vs. log intensity curves gave values of n between 0.6 and 1.0, and sigma (the stimulus intensity for a half maximal response) between 132-3700 quanta/microns2. Recovery of sensitivity did not always correspond to that of maximum response.

Adolescent↗
PubMed1990

Formation of "vessel-like" structures by retinal capillary endothelial cells in culture.

The formation of "vessel-like" structures has been previously reported in cultures of endothelial cells from both large and small vessels. In this study the formation of such tubular structures was observed in post-confluent cultures of bovine retinal microvascular endothelial cells. As the cells became postconfluent, cell dropout occurred and the remaining islands of cells were observed to be interconnected by cords. Electron microscopy demonstrated that each cord consisted of a continuous lumen surrounded by one or more endothelial cells. The mechanisms of in vitro "vessel formation" by retinal endothelial cells do not appear to relate to either those of embryonic retinal vascularisation or those associated with retinal neovascularisation and may be an unrelated phenomenon only expressed in vitro.

Animals↗
PubMed1990

Ion transport abnormalities in inflamed rat jejunum. Involvement of mast cells and nerves.

Basal and stimulated changes in ion transport in vitro were examined in jejunal mucosa from rats during inflammation produced after infection with the nematode Nippostrongylus brasiliensis. The gut was acutely inflamed at days 7 and 10 when net secretion of Na+ and Cl- ions was evident. Serum levels of rat mast cell protease II were elevated, providing evidence for mast cell activation. In addition, the magnitude of the short-circuit current responses to electrical transmural stimulation of enteric nerves (but not to histamine in the presence of neural blockade) were significantly reduced (p less than 0.01) to 17%-33% of control values, suggesting abnormalities of mucosal nerves. Following worm expulsion, serum levels of rat mast cell protease II and ion transport returned to normal. However, mastocytosis was apparent in gut mucosa and parasite antigen stimulated net secretion. In the absence of antigen, short-circuit current responses to nerve stimulation were increased (to 122% of controls; p less than 0.05). These findings suggest that changes in mast cells and enteric nerves occur during inflammation in this model and implicate neural and mast cell interactions with the epithelium in producing the ion-transport abnormalities.

Animals↗
PubMed1990

The HLA genetic constitution of the Bushmen (San).

The HLA-A, -B, and -C antigens of 290 and the DR antigens of 212 !Kung San individuals were characterized. The most frequent antigens were HLA-A30 [gene frequency (gf) = 0.193], Bw58 (gf = 0.303), Cw6 (gf = 0.327), DR4 (gf = 0.273), and DQw3 (gf = 0.553). An unexpected finding was the low frequency of the classic African black antigen Bw42 (gf = 0.004). Marked differences as well as similarities in HLA gene frequencies were observed between the San and the South African Negroes, supporting the view that they had a common origin and were then separated for a very long time. During this period differences developed as a result of selective advantage in the Negroes following the pastoralist-agriculturalist way of life as opposed to the hunter-gatherer way of life. The picture is further complicated by the fact that gene flow, mostly from the San to the southern African Negroes, took place when they met again a few hundred years ago. The data also illustrate HLA haplotypes, linkage disequilibria, and four-locus haplotypes not previously seen in other human populations. The most frequent four-locus haplotype in the San, HLA-Aw43,Cw7,B7,DRw6 was also different from A30, Cw2,Bw42,DR3, the most common among the South African Negroes.

Africa, Southern↗
PubMed1990

Cloning and expression of cDNA and genomic clones encoding three delayed rectifier potassium channels in rat brain.

Rat brain cDNA and genomic clones encoding three K+ channels, Kv1, Kv2, and Kv3, have been isolated by screening with Shaker probes and encode proteins of 602, 530, and 525 amino acids. Each of the deduced protein sequences contains six hydrophobic domains (including an S4-type region characteristic of many voltage-gated channels) and are 68%-72% identical to each other overall. Transcripts of approximately 3.5, approximately 6.5, and approximately 9.5 kb encode Kv1, Kv2, and Kv3, respectively. The Kv2 mRNA is expressed only in brain, whereas the Kv1 and Kv3 transcripts are found in several other tissues as well. There is a marked increase in the amount of Kv1 mRNA in cardiac tissue during development and a similar, but less pronounced, increase of both this mRNA and the Kv2 transcript in brain. RNAs synthesized in vitro from the three clones induce voltage- and time-dependent, delayed rectifier-like K+ currents when injected into Xenopus oocytes, demonstrating that they encode functional K+ channels.

Amino Acid Sequence↗
PubMed1990

Diet in the epidemiology of gastric cancer.

We examined the nutritional epidemiology of gastric cancer in 293 cases and neighborhood-, age-, and sex-matched controls in communities throughout the counties of Niagara, Monroe, and Erie in western New York. The interview was highly detailed, requiring two and one-half hours to complete; it attempted to provide an estimate of total calories ingested as well as of macro- and micronutrients and behaviors that could affect alimentary exposures, such as the use of refrigeration. We found that risk was enhanced by sodium, fat, and retinol. Substantial reductions in risk were associated with ingestion of carotene, especially raw vegetables (including celery, cucumbers, carrots, green peppers, tomatoes, and onions), as well as with increased use of low-temperature food storage. Both refrigeration and carotene could inhibit oxidation products that could act as carcinogens in the stomach.

Adult↗