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Biomedical subjects

J A Morgan

Publications and source records attributed to J A Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1995

Nuclear rDNA ITS sequence variation in the trematode genus Echinostoma: an aid to establishing relationships within the 37-collar-spine group.

The taxonomic history of members of the 37-collar-spine group within the genus. Echinostoma has been very confused. We obtained DNA sequence data from the nuclear rDNA ITS1, 5.8S and ITS2 of 7 nominal species belonging to this group, Echinostoma trivolvis (Cort, 1914), E. revolutum (Frölich, 1802), E. caproni Richard, 1964, E. liei Jeyarasasingam et al. 1972, E. paransei Lie & Basch, 1967, two African isolates, E. sp.I and E. sp.II, and of one 28-collar-spined echinostome, E. hortense (Asada, 1926). Five of the eight species were clearly distinguishable using ITS data. Sequences from the remaining three taxa, E. caproni, E. sp.II and E. liei were identical to one another and the group containing these taxa was distant from other 37-collar-spine species on a phylogenetic tree. E. trivolvis and E. paraensei form a second, but less distinct group within the 37-collar-spine group. The resolution obtained using DNA sequencing will assist in the current reclassification of the group. It also provides a model for future work on sibling species.

Animals↗
PubMed1995

Advances in the use of ancillary diagnostic testing in the emergency department evaluation of chest pain.

This article discusses the advances of ancillary studies used to evaluate the emergency department patient with chest pain caused by acute myocardial infarction (AMI) or ischemia. This article examines how these studies have improved the early detection of patients with AMI, improved differentiation of acute ischemic coronary events from nonischemic causes of chest pain, more accurately stratified patients for adverse outcome, and decreased the number of patients with AMI inadvertently discharged from the emergency department. Ancillary studies discussed include nonstandard ECGs, nuclear imaging, serum markers, and emergency department observation units. Emergency department echocardiography is discussed elsewhere in the issue.

Chest Pain↗
PubMed1994

Molecular cloning of two Pseudomonas flagellin genes and basal body structural genes.

Pseudomonas putida strains PaW8 and PRS2000 produce flagellins with apparent molecular masses of 81 kDa and 50 kDa respectively. Two Tn5 insertion mutants of P. putida PaW8 lacking the ability to bind the flagellin-specific monoclonal antibody MLV1 were isolated. Mutant PaW8-flg2 contained a Tn5 insertion within a 2.6 kb EcoRI fragment of the P. putida chromosome carrying putative basal body genes. DNA and deduced protein sequences suggested the presence on this fragment of two complete genes homologous to flgH and flgI from Salmonella typhimurium. The insertion of Tn5 occurred in the flgI locus and appeared severely to reduce expression of the P. putida flagellin gene. A Tn5-containing fragment of DNA from a second mutant, PaW8-flg1, was cloned and found to contain sequences that hybridized strongly with the Pseudomonas aeruginosa flagellin gene. A 2.3 kb HindIII fragment containing all but 62 bp of the P. putida PaW8 flagellin gene was cloned and used as a probe to identify clones carrying the equivalent gene from P. putida PRS2000. Flagellin genes from both P. putida strains were sequenced and their amino acid sequences deduced. Both flagellins were found to contain conserved amino- and carboxy-terminal regions when compared to other flagellins, with the central region being more variable. The epitope for MLV1 is likely to lie within this central region of P. putida PaW8 flagellin. The deduced molecular mass of P. putida PaW8 flagellin (68 kDa) differed significantly from its apparent molecular mass estimated by PAGE, possibly as a consequence of post-translational modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Elimination of glutathione-induced protection from hyperbaric hyperoxia by acivicin.

Glutathione (GSH) administered intraperitoneally significantly prolongs the time to initial seizure and survival time of rats exposed to hyperbaric hyperoxia (HBO). Acivicin is an antitumor antibiotic that is an inhibitor of gamma-glutamyl transpeptidase (GGT), an enzyme necessary for the breakdown and transport across cell membranes of GSH. To determine whether acivicin treatment alters GSH-induced protection from HBO, rats were dosed with 25 mg/kg of acivicin or vehicle 1 h before O2 exposure at an inspired O2 fraction of 1.0 at 4 ATA. Immediately before exposure, rats received GSH (1 mmol/kg) or vehicle. Time to seizure and time to death were recorded during exposure by direct observation. In separate groups of rats on the same dosing schedule, plasma GSH, renal GGT, and brain GGT were measured 15 min after the GSH injection without HBO exposure and 100 min after the beginning of HBO exposure. Renal GGT was decreased to 2.5% of control and brain GGT to 37% of control in the acivicin-dosed rats. Plasma GSH increased 3-fold in rats given acivicin alone, 52-fold in rats given GSH alone, and 84-fold in rats receiving both acivicin and GSH. Rats dosed with GSH alone had significantly prolonged times to seizure and death compared with all other groups. Rats dosed with GSH after receiving acivicin were not protected from HBO despite the large increase in plasma GSH that occurred in these animals. GSH treatment did not increase tissue GSH in lung, liver, or brain at 160 or 200 min of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Protein kinase C and intracellular free Ca++: relationship to human immunodeficiency virus (HIV)-induced cellular hyporesponsiveness.

Protein Kinase C (PKC) and Ca++ are both involved in the chain of events leading to T-cell activation. An impairment of the immune response is characteristic of T cells obtained from patients with HIV infection. In this report, the involvement of PKC and Ca++ in HIV-mediated cellular hyporesponsiveness was examined. Infection of peripheral blood mononuclear cells (PBMC)s from HIV-seronegative normal donors with HIV strain HTLV IIIB, or two fresh patient isolates produced a 1.4-, 10.7-, and 11.4-fold enhancement in PKC activity at 1 hr postinfection (PI) and a 1.8-, 2.3-, and 3.8-fold enhancement at 12 hr PI, respectively. A marked decrease of PKC content, as determined by Western Blot analysis, was observed in HIV-infected cells by Day 4 and 7 PI compared with mock-infected control cells. Furthermore, PKC synthesis was also inhibited in cells from immunosuppressed AIDS patients. PKC activity of PBMCs from HIV-infected patients did not change in response to 1 microM of phorbal myristate acetate (PMA). In contrast, the same dose enhanced the activity by 50%-100% in PBMCs from normal HIV-seronegative donors. A 40%, 50%, and 125% increase in intracellular free Ca++ in response to HIV infection was observed 12 hr PI in MT4, JURKAT, and PBMCs, respectively. However, the increase in intracellular free Ca++ in HIV-infected PBMCs obtained from normal donors in response to PHA was 56% and 17% compared with an increase of 100% and 120% in mock infected cells at 12 hr and 1 week PI, respectively. Comparing the Ca++ response to PHA in PBMCs from HIV-infected patients showed that patients with < 250 absolute T4 cells/mm3 had an impaired Ca++ response. These data suggest that there is a relationship between intracellular free Ca++ and PKC and HIV-induced T-cell hyporesponsiveness.

Calcium↗
PubMed1993

The role of ultrasound assisted thoracoscopy in the diagnosis of pleural disease. Clinical experience in 687 cases.

Ultrasonic examination is an established method used to differentiate between solid and liquid structures in the pleural space. It can estimate the volume of a pleural effusion and demonstrate whether the effusion is associated with loculations or adhesions. It is complementary to thoracoscopy. In the diagnosis of pleural disease ultrasonic-assisted thoracoscopy should only be used when the less invasive methods of diagnosis such as pleural aspiration for cytological, bacteriological and chemical examinations and needle biopsy of the pleura have not yielded a diagnosis. Although thoracoscopy is a relatively invasive procedure, it has the advantages of speed and accuracy in the diagnosis of pleural disease. This procedure is not widely used as it requires specialized instruments and equipment and may be time-consuming. The latter disadvantage may be minimized by the use of prior pleural sonography. The ultrasonic examination will indicate the optimal point of entry of the thoracoscopy to avoid adhesions. In order to evaluate feasibility, complications and clinical results in ultrasonic-assisted thoracoscopy, we investigated 687 patients with pleural diseases from 1987 to 1990. As prior induction of a pneumothorax under X-ray control was not necessary, the 20-30 min required for this procedure was saved in all patients. Very few complications were attributable to ultrasonic-assisted thoracoscopy as it could normally be performed under local anesthesia. A macroscopic diagnosis was made in 80% of malignant diseases and 77% of inflammatory diseases in our total of 687 thoracoscopies. The diagnosis of a malignant pleural effusion was confirmed histologically and cytologically in 95% of those 190 patients in whom it was present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Rapid, automated separation of specific bacteria from lake water and sewage by flow cytometry and cell sorting.

The use of fluorescence-activated flow cytometric cell sorting to obtain highly enriched populations of viable target bacteria was investigated. Preliminary studies employed mixtures of Staphylococcus aureus and Escherichia coli. Cells of S. aureus, when mixed in different proportions with E. coli, could be selectively recovered at a purity in excess of 90%. This was possible even when S. aureus composed only approximately 0.4% of the total cells. Cell sorting was also tested for the ability to recover E. coli from natural lake water populations and sewage. The environmental samples were challenged with fluorescently labelled antibodies specific for E. coli prior to cell sorting. Final sample purities of greater than 70% were routinely achieved, as determined by CFU. Populations of E. coli released into environmental samples were recovered at greater than 90% purity. The use of flow cytometry and cell sorting to detect and recover viable target bacteria present at levels of less than 1% within an indigenous microflora was also demonstrated.

Antibodies, Bacterial↗
PubMed1993

Survival of nonculturable Aeromonas salmonicida in lake water.

The survival of Aeromonas salmonicida subsp. salmonicida was investigated in sterile and untreated lake water. In sterile lake water (filtered and autoclaved), it was found that cells of A. salmonicida entered a nonculturable but viable condition. Viability was determined by flow cytometry with the dye rhodamine 123, which is taken up and maintained within cells with a membrane potential. For survival studies in untreated lake water, A. salmonicida was marked with the xylE gene by using the plasmid pLV1013. Marked cells were detected by growth on tryptone soy agar and tryptone soy agar supplemented with kanamycin. Cells were also detected by polymerase chain reaction DNA amplification of the xylE gene and a chromosomal DNA fragment specific for A. salmonicida (pLV1013). The results indicated that A. salmonicida entered a nonculturable condition in untreated lake water over a 21-day study. The viability of nonculturable cells could not be determined in mixed samples; however, the presence of nonculturable cells containing both chromosomal and plasmid DNA was confirmed.

Aeromonas↗
PubMed1992

[A new single-lumen endobronchial tube for artificial respiration following pneumonectomy in thoracic surgery].

If a patient who has undergone a major resection such as a pneumonectomy or radical pneumonectomy develops during the postoperative period respiratory failure requiring mechanical ventilation, this may cause problems with the respirator treatment. It is of particular interest that the newly sutured bronchus stump can be protected from high ventilation pressures. Until now, patients who have undergone pneumonectomy have been ventilated using a single lumen tube or a double lumen tube (Table 1). A major complication often leading to death is a bronchial stump dehiscence giving rise to a bronchopleural fistula on the operated side due to aggressive mechanical ventilation. Therefore, we developed a new single lumen endobronchial tube (produced by Willy Rüsch AG, W-7050 Waiblingen, Germany, Cat.No. 115900) for the mechanical ventilation of pneumonectomised patients (Fig. 1). The sutured bronchial stump lies between the bronchial and tracheal cuff (Fig. 2) and for that reason is not exposed to any increased ventilation pressure. This new tube contributes to a lower complication rate in mechanically ventilated patients after pneumonectomy.

Bronchi↗
PubMed1992

Non-culturable Aeromonas salmonicida in lake water.

The survival of Aeromonas salmonicida subsp. salmonicida was investigated in lake water. During a 21-day study A. salmonicida became non-culturable in sterile lake water held at 10 degrees C. The incubation of replicate samples between 5 degrees C and 25 degrees C produced similar results. The recovery of colony-forming units of A. salmonicida from different lake water systems indicated that they survived longer in water that was naturally enriched (eutrophic) or enriched with tryptone soya broth. Flow cytometry, fluorescence light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that non-culturable cells were present. These cells could not be revived in dilutions of tryptone soya broth, whole dead fish or dissected fish tissue. Although viability could not be proven, it was shown that the morphological integrity found in viable cells was also maintained in non-culturable cells.

Aeromonas↗
PubMed1992

The effect of microcosm design on the survival of recombinant Pseudomonas putida in lake water.

The survival of Pseudomonas putida marked with the xylE gene was monitored in lake-water microcosms. Various designs of microcosms were compared. These ranged from 250-ml conical flasks containing 100 ml surface lake water to 12-1 glass containers with lake water overlying sediment, continuous aeration and a supply of fresh surface lake water. The presence of a low flow-through rate was shown to have little effect on the survival of P. putida. An increase in the size of microcosm, presence of sediment and aeration had a significant effect on survival in lake water and increased the rate of decline of released cells. The implication of these results in predicting the survival of P. putida in lake water using microcosms is discussed.

Genes, Bacterial↗
PubMed1991

Envenomation by the puss caterpillar (Megalopyge opercularis).

We discuss the case of a 52-year-old woman who developed urticarial lesions after the acute envenomation of a puss caterpillar (Megalopyge opercularis). The puss caterpillar, one of more than 50 species of caterpillars that can cause envenomation in the United States, is considered to be one of the most serious. Its clinical presentation and current recommended treatments are reviewed.

Animals↗
PubMed1991

Rapid Immunocapture of Pseudomonas putida Cells from Lake Water by Using Bacterial Flagella.

Monoclonal antibodies to Pseudomonas putida Paw340 cells were produced. In an enzyme-linked immunosorbent assay (ELISA) against whole bacterial cells, a hybridoma cell line termed MLV1 produced a monoclonal antibody that reacted with P. putida Paw340 but showed no cross-reaction with 100 medical isolates and 150 aquatic isolates. By ELISA, immunogold electron microscopy, and Western blot (immunoblot) analysis, MLV1 antibody was found to react with purified bacterial flagella. The surfaces of magnetic polystyrene beads were coated with MLV1 antibody. By mixing MLV1 antibody-coated beads with lake water samples containing the target P. putida host, bead-cell complexes which could be recovered by attraction towards a magnet were formed. Prevention of nonspecific attachment of cells to the beads required the incorporation of detergents in the isolation protocol. These detergents affected colony-forming ability; however, the cells remained intact for direct detection. When reisolated by standard cultural methods, approximately 20% of the initial target population was recovered. Since the beads and bead-cell complexes were recovered in a magnetic field, target bacteria were separated from other lake water organisms and from particulate material which was not attracted towards the magnet and were thereby enriched. This method may now provide a useful system for recovering recombinant bacteria selectively from environmental samples.

Journal Article↗