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Biomedical subjects

E Murphy

Publications and source records attributed to E Murphy.

At least 271 records · Page 15Linked to original sources
PubMed1984

A comparative study of bed usage by younger and older patients with depression.

Recent follow-up studies of depression in old age have highlighted the high relapse rate in older patients compared with younger patients. The consequences for the provision of acute psychiatric beds for elderly patients has been investigated by comparing the usage of beds by younger and older patients with depression over a 4-year period. Overall, elderly depressed patients consumed one and a half times as many bed days as younger depressed patients and a quarter of all acute bed days available in the hospital were used by elderly depressed patients.

Adolescent↗
PubMed1984

Survey of the dental health and denture status of institutionalized elderly patients in Ireland.

An investigation was conducted to establish the dental status of 368 elderly patients in two geriatric hospitals in Limerick, Ireland, in terms of denture status and the number of teeth present. Seventy eight percent of those examined were edentulous, but only 27% of edentulous patients were wearing maxillary and mandibular dentures. A further 18% wore a maxillary denture only, 21% had dentures made but no longer wore them, and 33% had never had dentures. Forty-four patients had some maxillary and mandibular teeth present and 20 of these had sufficient teeth for masticatory purposes. Very few patients, edentulous or dentate, complained of any problems, although 27 were felt to require extraction of one or more teeth.

Aged↗
PubMed1984

Gentamicin uptake in Staphylococcus aureus possessing plasmid-encoded, aminoglycoside-modifying enzymes.

[3H]gentamicin uptake and killing were studied in three strains of gentamicin-resistant Staphylococcus aureus possessing plasmid-encoded, gentamicin-modifying enzymes and in three isogenic, enzyme-free, gentamicin-susceptible derivatives. At low (less than or equal to 2.0 micrograms/ml) concentrations of gentamicin, uptake by resistant organisms was impaired compared with that of susceptible strains, and no killing was noted. In contrast, at higher (2.5 to 10.0 micrograms/ml) concentrations (which were below the MIC for the resistant strains), rapid gentamicin uptake similar to that seen in susceptible isolates was observed. Although growth inhibition at these concentrations was apparent, there was no loss of viability in resistant strains. Consistently, the membrane H+-ATPase inhibitor N,N'-dicyclohexyl carbodiimide caused resistant strains to take up low concentrations (1.0 microgram/ml) of gentamicin at rates comparable to those seen in susceptible organisms without causing an associated loss of viability. These studies show differences between gentamicin uptake in S. aureus and streptomycin uptake in Escherichia coli (Dickie et al., Antimicrob. Agents Chemother. 14:569-580, 1978) regarding the kinetics of uptake in resistant strains with plasmid-encoded aminoglycoside-modifying enzymes. Specifically, they suggest that for 2-deoxystreptamine compounds such as gentamicin, ribosomal binding followed by accelerated uptake and subsequent interference with cell growth may occur without invariably being associated with lethal effect.

Dicyclohexylcarbodiimide↗
PubMed1984

Histamine and slow reacting substance in acid-induced pneumonitis.

Acid pneumonitis was produced in 18 dogs by the tracheal instillation of 3 ml/kg 0.1 N hydrochloric acid. Arterial and mixed venous oxygen tension, static compliance and pulmonary capillary wedge pressure were measured during a 2-hour observation period. Plasma histamine (measured by the enzymatic isotopic assay) increased from 1.7 +/- 0.2 ng/ml (mean +/- SE) before acid injury to 13.5 +/- 1.9 ng/ml after injury (p less than 0.05). In one group of 7 control dogs, 3 ml/kg of normal saline produced no increase in plasma histamine. Pulmonary edema secretions from acid injured animals had a histamine level of 30.3 +/- 3.8 ng/ml and slow reacting substance was detected in 7 of 11 animals. The slow reacting substance was an antihistamine-resistant, ethanol extractable substance that contracted guinea pig ileum. Lung weight-body weight ratio PaO2, and static compliance were different with acid pneumonitis compared to controls. Total protein was not different in the tracheal secretions compared to plasma. We conclude that histamine and slow reacting substance are released in this animal model of acid pneumonitis and may be important in the pathogenesis of the lung injury.

Animals↗
PubMed1984

Oncogene expression in human leukemia.

The transforming genes of retroviruses (v-onc) are derived from normal cellular genes referred to as proto-oncogenes. These cellular genes have the capacity for conversion to oncogenes (c-onc) that are capable of inducing or maintaining the transformed state when they are overly expressed or altered by mutation or rearrangement. To study the possible involvement of these genes in human leukemia, we have analyzed their expression in a variety of fresh samples. We found that a number of oncogenes are expressed in different leukemic types and that although the transcript size did not vary for each gene, the copy number did. The myc gene (2.4 kb transcript) and the rasHa gene (1.5 kb transcript) were universally expressed. But in contrast to rasHa, the myc signal intensity varied. Myb (4.5 kb transcript) was expressed in all samples except B cell diseases. We detected low levels of abl expression (multiple mRNA species) in all leukemic types analyzed. Sis gene (4.2 kb transcript) expression was restricted to one patient sample with chronic myelogenous leukemia in blast transformation.

Acute Disease↗
PubMed1984

Physiologic criteria for electrogenic transport in tissue-cultured heart cells.

A description of the physiologic criteria for electrogenic transport in cultured heart cells must consider the direct as well as the indirect contributions of the electrodiffusive and electroneutral transport mechanisms of the kind described in this chapter. It is important to recognize that fundamental transport processes whether active, passive, or coupled-passive, do not operate in isolation but function rather as an interrelated network represented by the example in Fig. 8. The results of our studies point to the importance of providing an accurate, quantitative description of the transmembrane movement of sodium, because this ion is intricately involved in the overall regulation of several transport mechanisms in cardiac muscle. Cultured heart cell preparations enable the rapid exchange of extracellular space essential to the study of complex transport mechanisms. These preparations have thus enhanced our understanding of the magnitude and interplay of exchange fluxes that may eventually be implicated in the repolarization phase of the cardiac action potential and genesis of pacemaker potentials.

Biological Transport↗
PubMed1983

Inhibition of Tn554 transposition: deletion analysis.

Tn554, a transposon in Staphylococcus aureus that specifies resistance to erythromycin and spectinomycin, exhibits a high preference for a single chromosomal insertion site. If this site is already occupied by a copy of Tn554, the transposition of a second element is inhibited 100- to 1000-fold. This report defines the locus of the inhibitory activity and presents both a functional and a restriction map of Tn554. Fragments containing parts of Tn554 were cloned on an autonomously replicating plasmid. Those clones containing the "left" end of Tn554 strongly inhibited the transposition of an incoming, intact copy of Tn554. Analysis of deleted derivatives of these clones defined a locus tnpI, which is both necessary and sufficient for transpositional inhibition. This locus consists of the terminal 89 bp of the "left" end of Tn554. It is suggested that this terminal sequence acts to titrate a factor required for transposition.

Cloning, Molecular↗
PubMed1983

Calcium elevation in cultured heart cells: its role in cell injury.

Inhibition of the Na+-K+ pump in cultured embryonic chick heart cells promotes the elevation of intracellular Ca2+ and is a useful manipulation to study the relationship between Ca2+ and myocardial cell injury. One hour of Na+-K+ pump inhibition resulted in a fourfold increase in cell Na+, a 50% decline in cell K+, and a 5- to 10-fold increase in cell Ca2+, 45% of which is mitochondrial. The degree of cell injury induced by Ca2+ loading was evaluated by monitoring the content of adenosine 5'-triphosphate (ATP) and the release of the intracellular enzyme lactate dehydrogenase (LDH). Under these conditions ATP content declined by 25-30% and LDH release increased from 1 to 1.4% of the total LDH. Furthermore, cells subjected to 1 h of Na+-K+ pump inhibition and returned to control solution for 5 h showed that Ca2+ decreased to near control levels and ATP content was restored. Although inhibition of Na+-K+ transport caused a large increase in cell Ca2+, neither Na+-K+ pump inhibition nor elevation in total cell Ca2+ per se resulted in irreversible myocardial cell injury.

Adenosine Triphosphate↗
PubMed1983

The prognosis of depression in old age.

The paper describes a one year prospective study of 124 elderly depressed patients. Only one third of the group had a good outcome. Poor outcome was associated with severity of initial illness, those with depressive delusions having a particularly poor outcome. Outcome was also influenced by physical health problems and severe life events in the follow-up year. Social class differences in outcome were thought to be due to class differences in the experience of severe life events. There was no evidence that an intimate relationship protected against relapse in the face of continuing life stress.

Aged↗
PubMed1983

N6-Methyladenosine inhibition of hypoxanthine uptake by Chinese hamster ovary cells.

The effects of an adenosine analog, N6-methyladenosine, on the uptake of purines by Chinese hamster ovary (CHO) cells were investigated. Surprisingly, N6-methyladenosine was a more potent inhibitor of the uptake of the 6-hydroxy purines, hypoxanthine and inosine, than of the 6-amino purines, adenine and adenosine. Hypoxanthine uptake was the most profoundly inhibited. The inhibition of hypoxanthine uptake by N6-methyladenosine was dose dependent. Kinetics experiments demonstrated that N6-methyladenosine is a competitive inhibitor of hypoxanthine uptake with a Ki of 30 uM. The effect of N6-methyladenosine on hypoxanthine transport in the absence of metabolism was determined in CHO AK412 cells which lack hypoxanthine phosphoribosyltransferase (HPRT). Hypoxanthine transport by HPRT deficient cells suspended in serum-free medium containing 2 uM hypoxanthine was inhibited by N6-methyladenosine in a dose-dependent manner. When HPRT deficient cells were preincubated for 15 min in 200 uM N6-methyladenosine, a concentration which when present during the transport assay reduces transport to 5% of control, the subsequent transport of hypoxanthine in the absence of inhibitor was 65% of control. This finding suggests that the effects of N6-methyladenosine on hypoxanthine transport are readily reversible. In HPRT deficient cells N6-methyladenosine was a far more effective inhibitor of hypoxanthine transport than adenosine.

Adenine↗
PubMed1983

Three-dimensional configuration of the mitochondria in cultured heart cells.

The mitochondria of chick heart cells grown in monolayer culture occupy a relatively large percentage (30%) of the cell cytoplasmic volume, as determined by thin section morphometry, and vary in their ultrastructural configuration in response to different functional states of the cell. The present study was undertaken to determine the three-dimensional structure of the mitochondria in cardiac cells, since reconstruction experiments have demonstrated the existence of a mitochondrial network in cardiac and other tissues, e.g. diaphragm, soleus and vastus muscle, kidney and urinary bladder, in vivo. Confluent monolayers of synchronously beating embryonic chick heart cells were fixed, stained with a mitochondria-specific heavy metal complex (Pb-Cu citrate), and processed for either transmission electron microscopy (TEM) or scanning electron microscopy (SEM) and backscatter electron imaging (BSI). Both secondary and backscatter images revealed the presence of many thin, extremely elongate structures which in stereo views appeared as branching, anastomosing networks. TEM demonstrated localization of the electron dense stain to either nuclear or mitochondrial membranes, structures which were easily distinguished with SEM or BSI alone. These morphological results indicate that many mitochondria of the cultured heart muscle cell are interconnected and suggest that this morphological network may represent a parallel functional unit which maintains the energy state of the cell.

Animals↗