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Biomedical subjects

D Jones

Publications and source records attributed to D Jones.

At least 739 records · Page 41Linked to original sources
PubMed1981

Evidence for endothelial cell origin of vinyl chloride-induced hepatic angiosarcoma.

Previous reports of hepatic angiosarcoma have not clearly defined the cellular type from which this tumor arises, as evidenced by the terminology of endothelioma, Kupffer cell sarcoma, endothelial cell sarcoma, and hemangioendothelial sarcoma, etc., which have been used interchangeably. In addition, there has been no consensus on the separate entity of Kupffer and sinusoidal endothelial cells. In the work presented here, evidence for the endothelial cell origin of this tumor is provided by the demonstration of factor VIII, a known endothelial cell marker, in the tumor cells. Fluorescence due to the presence of factor VIII appeared intense in the tumor sinusoidal cells of all four vinyl chloride-associated angiosarcomas studied, whereas normal liver sinusoidal lining cells showed negligible fluorescence.

Endothelium↗
PubMed1980

Magnesium and calcium in the myocardium: cause of death and area differences.

In a study of myocardial magnesium and calcium levels in 1236 samples of heart muscle taken at necropsy in 28 centres in England and Wales, samples from patients who died from ischaemic heart disease had a mean Mg level 23 microgram/g lower and a mean Ca level 4 microgram/g higher than the mean for the total series after allowance had been made for a number of relevant factors. Mg levels were slightly higher and Ca levels slightly lower in sudden than in lingering deaths. There was no evidence of any association between the tissue levels and the levels of Mg or Ca in domestic tap-water, but there was a weak association between mean tissue Mg level and IHD mortality rates in the various towns.

Adult↗
PubMed1980

Perspective on care.

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Health Services Administration↗
PubMed1980

Neuroendocrine regulation of corpus allatum activity in Manduca sexta: Sequential neurohormonal and nervous inhibition in the last-instar larva.

The inactivation of corpora allata (CA) in the last-instar larva of the tobacco hornworm Manduca sexta was studied using in vivo assay methods that test the capacity of the glands to induce an extra larval molt. Results indicate that the CA are inactivated by a two-step process. In the first step, a neurohormonal inhibition occurs by day 1 after ecdysis, resulting in a decrease in the ability of the glands to respond to allatotropin. The inhibitory hormone appears to be secreted by the medial neurosecretory cells in the brain and remains in the hemolymph only for a short period of <2 days. The second step of inactivation occurs by day 3; it is neurally mediated and essentially terminates juvenile hormone secretion. Neither the neurohormonal nor the neural inhibition is reversible under the conditions used in our larval assays. The timing of the two stages of inhibition coincides with the two periods of reduction in hemolymph juvenile hormone titer; this suggests that the regulation of corpus allatum activity plays an important role in reducing the juvenile hormone titer during the last larval instar-a prerequisite for the transformation of the larva into the pupa.

Journal Article↗
PubMed1979

The distribution of isoprenoid quinones in streptococci of serological groups D and N.

The isoprenoid quinone contents of streptococci of serological groups D and N were investigated. Streptococcus faecalis, S. faecalis subsp. liquefaciens and S. faecalis subsp. zymogenes strains contained demethylmenaquinones with nine isoprene units as their major isoprenologues. Menaquinones with eight isoprene units predominated in S. faecium subsp. casseliflavus and S. faecium subsp. mobilis whereas menaquinones with nine isoprene units constituted the major components in strains of S. cremoris, S. cremoris subsp. alactosus, S. lactis and S. lactis subsp. diacetylactis. Strains of S. avium, S. bovis, S. durans, S. equinus, S. faecium, S. raffinolactis and S. suis contained neither menaquinones nor ubiquinones. The isoprenoid quinone data correlate well with other kinds of data on these organisms and are of value in the classification of these bacteria.

Enterococcus faecalis↗
PubMed1979

Short-term recall of nine-digit strings and the EEG.

In three exploratory studies, EEG changes were monitored while subjects performed a nine-digit recall task. Experiment 1 involved auditory presentation without practice or prior instruction. EEG characteristics measured before the task related to subsequent recall, EEG activation increased progressively during digit presentation and rehearsal, and several between- and within-subject analyses showed increased activation to be associated with poor recall performance. In Expt. 2 the digits were presented visually and subjects were given instruction and practice in an efficient rehearsal strategy. Recall performance improved but its relationship with the pre-task EEG disappeared. Activation increased with digit presentation but the relationship between the EEG and performance was complex since a within-subject analysis associated decreased activation with better performance (as in Expt. 1) while this relationship was reversed in a between-subject analysis. The results are explained both in terms of traditional findings relating activation to recall, and drive theory accounts of learning and performance. Finally, Expt. 3 demonstrated that performance was better, both in the morning (compared with the evening) and on a second testing session. There were complex time of day effects for the EEG, with lower and higher measured frequencies yielding higher voltage output in the evening and intermediate frequencies showing a reverse effect. In summarizing the data from the three experiments it is suggested that different EEG frequencies are differentially sensitive to different conditions (task specific factors, stimulus input characteristics, knowledge of success and failure, degree of task mastery and circadian variation).

Arousal↗
PubMed1979

Methicillin-resistant strains of Staphylococcus aureus phage type 92.

Methicillin-resistant (Mec(r)) strains of Staphylococcus aureus received for phage typing from several hospitals in New York City were resistant to the international set of typing phages but susceptible to experimental phage 92. Subsequently, strains of type 92 were detected in two outbreaks with Mec(r) strains in two other locations in the United States. In all instances, type 92 was predominant among the Mec(r) strains isolated in each hospital. With the exception of one strain, the methicillin resistance of the Mec(r) strains investigated was homogeneous. In most instances, isolates from the same hospital were closely similar in their antibiotic resistance patterns. The strains isolated in New York City could be divided into three groups by the host range of their lysogenic phages and by antigenic structure. Transduction experiments indicated that the transfer of chromosomal tetracycline resistance from Mec(r) strains into a strain susceptible to several international typing phages renders the latter nontypable. However, the acceptor strain remains susceptible to experimental phages 92 and 88. Transduction of methicillin resistance had no effect on the phage susceptibility of the acceptor strain. It is possible that the presence of chromosomal tetracycline resistance is a determining factor in the phage susceptibility of Mec(r) strains isolated in New York City.

Bacteriophage Typing↗
PubMed1978

Short-term memory and the EEG: effects of instructions to rehearse.

Transoccipital EEG was analyzed during the performance of a task involving the presentation and recall of auditorily presented nine-digit strings. Three strategies of processing were imposed by instruction: (i) passive listening without recall; (ii) passive listening followed by attempted recall; (iii) active rehersal followed by attempted recall. Phasic EEG arousal (8.5-12.5 Hz), inferred from the decline in abundance during string presentation, was found to be a function of the level of 'engagement' in the task. This finding was viewed as supporting an earlier phenomenological description of the task demands involved in recall. Tonic levels of arousal were found to be frequency dependent. At low frequencies (8.5-10.5 Hz) EEG abundance was inversely related to engagement but at higher frequencies (10.5-12.5 Hz) abundance was directly related to the level of engagement. The results are discussed in terms of a possible functional dissociation of EEG arousal within the alpha frequency band.

Brain↗