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Biomedical subjects

J A Morgan

Publications and source records attributed to J A Morgan.

16 recordsLinked to original sources

[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

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

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

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

Survival of Aeromonas salmonicida in lake water.

The survival of Aeromonas salmonicida subsp. salmonicida in lake water was investigated by using a variety of techniques. They included acridine orange epifluorescence, respiration, cell culture, cell revival, flow cytometry, plasmid maintenance, and membrane fatty acid analysis. During a 21-day study, A. salmonicida became nonculturable in sterile lake water samples. Flow cytometry and direct microscopy indicated that cells were present. Although the nonculturable cells could not be revived, the recovery method did indicate that the presence of low numbers of culturable cells within samples could produce misleading results. Plasmid DNA, genomic DNA, and RNA were maintained in the nonculturable cells; in addition, changes in the fatty acid profiles were also detected. Although viability could not be proven, it was shown that the morphological integrity of nonculturable cells was maintained.

Aeromonas

Use of a xylE marker gene to monitor survival of recombinant Pseudomonas putida populations in lake water by culture on nonselective media.

IncQ marker plasmids were previously constructed to enable the analysis of the survival of populations of Pseudomonas putida released into lake water (C. Winstanley, J. A. W. Morgan, R. W. Pickup, J. G. Jones, and J. R. Saunders, Appl. Environ. Microbiol. 55:771-777, 1989). We constructed equivalent IncP plasmids, pLV1016 and pLV1017, to provide conjugative alternative systems. Detection of the xylE gene carried by marker plasmids was found to be a valid indicator to use for studying the survival of released populations by culturing on nonselective media. These plasmids were used to study the survival of populations of Pseudomonas putida in both sterile and untreated lake water. The effects of inoculum size, the metabolic burden imposed on the cell by the unregulated expression of xylE, and an auxotrophic mutation carried by the host strain were studied. We also assessed the reproducibility and hence the predictability of the survival of released populations. Model systems with a single lake water sample and model systems with three different lake water samples, taken from the same site in consecutive months, were used to analyze variability between replicates and to assess differences caused by host strain or water sample. A large variability was found depending on which water sample was used. These findings imply that it will be difficult to predict accurately the survival of released populations in the natural environment.

Catechol 2,3-Dioxygenase

Molecular biology: new tools for studying microbial ecology.

The general aim of studies in microbial ecology is to determine the activities of particular groups of organisms in the natural environment. Current developments in molecular biology are providing methods that can be adopted for investigations in microbial ecology. Presently, molecular techniques are being used to determine population and community structures in samples. Following on from this, methods are needed to determine the activities of these organisms in their natural state. This review describes the application of molecular techniques to the study of micro-organisms in environmental samples.

Bacteria

Charcot-Marie-Tooth disease with Leber optic atrophy.

A family is described in which visual failure was associated with hypertrophic Charcot-Marie-Tooth disease. The diagnosis of Charcot-Marie-Tooth disease was confirmed by electrophysiologic studies and by quantitative histologic studies of sural nerve biopsies. The clinical features and mode of inheritance of the visual failure were those of Leber optic atrophy. The two conditions were inherited independently.

Adolescent

Electrophysiological studies in familial spastic paraplegia.

Motor and sensory conduction studies have been performed in 10 patients from three families with uncomplicated familial spastic paraplegia whose ages ranged from 4 to 41 years. In all cases the values fell within the control range. The findings may be contrasted with those in Friedreich's ataxia and some other spinocerebellar degenerations in which peripheral nerve abnormalities are present.

Action Potentials

Electrophysiological and pathological studies in spinocerebellar degenerations.

Electrophysiological and pathological studies have been performed on the peripheral nerves of patients with spinocerebellar degenerations. In Friedreich's ataxia there is impairment of sensory conduction and mild slowing of motor conduction which may be correlated with loss of large diameter fibres in the sural nerve. The abnormalities in Friedreich's ataxia are present early, in the first decade. In hereditary spastic paraparesis the nerve conduction studies and sural nerve biopsy are normal. In the other spinocerebellar degeneration and a mild loss of myelinated fibres in the sural nerve. However the abnormalities differ from those seen in Friedreich's ataxia.

Cerebellar Diseases

A family with Charcot-Marie-Tooth disease and Leber's optic atrophy.

A family has been studied in which members of 4 generations were affected by the hypertrophic type of Charcot-Marie-Tooth disease. The diagnosis was confirmed by electrophysiological studies and by sural nerve biopsy. 10 members of the family, 8 males and 2 females, developed optic atrophy of acute onset with progression over a period of two to six months. The history of visual failure, its maternal inheritance, and the neuro-ophthalmological findings of optic atrophy with bilateral central scotomata were typical of Leber's optic atrophy. 2 members of the family suffered from both Charcot-Marie-Tooth disease and Leber's optic atrophy. There have been a few previous reports of optic atrophy associated with Charcot-Marie-Tooth disease, and in the present family both conditions appeared to have been inherited independently.

Adolescent