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Biomedical subjects

D J Stone

Publications and source records attributed to D J Stone.

At least 55 records · Page 3Linked to original sources
PubMed1988

Anesthetic action of opiates: correlations of lipid solubility and spectral edge.

The ability of opiates to be a complete anesthetic has been assessed in animals. These studies have investigated the serum levels of opiate required to produce a decrease in anesthetic requirement for a concomitantly administered inhalation anesthetic. A linear dose-response relation has been observed between opiate serum level and reduction in anesthetic requirement up to the level of 50% reduction in minimum alveolar anesthetic concentration (MAC). These studies have not demonstrated the production of one MAC anesthesia by the opiates. Recent EEG studies have provided another means of comparing the central nervous system effects of opiates and inhalation anesthetics. The serum levels of several opiates associated with a 50% reduction (IC50 or 50% inhibitory concentration) in maximal spectral edge frequency (SEF) have been reported. The free, unionized serum levels of each opiate at IC50 in humans or 50% MAC reduction in animals are remarkably similar. We calculated brain lipid opiate content at these serum levels using available physiochemical data. The calculated nanogram and molar brain lipid contents of the drugs fell within a 10-fold range while serum levels varied by 5000-fold. This similarity in membrane lipid content in association with EEG and anesthetic effects suggests that opiate "anesthesia" may involve a membrane effect in addition to the well established receptor interaction.

Anesthesia, Inhalation↗
PubMed1988

Onchocerciasis in Ecuador: recent observations in the province of Esmeraldas.

To evaluate the transmission of onchocerciasis that had occurred in the past 6 years in the province of Esmeraldas, in 1986 the onchocercal focus was re-examined using the same methodology as in the original survey of 1980. An increased prevalence of infection of 73.9% was noted, with an increase of 73.0% found in the principal focus, the Santiago Basin, and a 76.7% increase in the satellite foci. In the principle focus, a higher increase was noted on the Rio Santiago (88.8%) than on the Rio Cayapas (68.6%), while an increase of only 39.7% was seen on the Rio Onzoles. Geographical extension of both the onchocercal focus and its respective hyperendemic areas were found on the Rio Cayapas and Rio Santiago. A higher increased prevalence of infection was found in the children (210.0%) than in the adults (29.5%). In the satellite foci, the Rio Canande showed the higher increase of infection (146.4%), with an increase of 61.3% seen in adults and 1409.1% in children. Active transmission of the disease exists in all onchocercal foci, each with its distinct and varying intensity.

Adult↗
PubMed1987

Roentgenographic patterns of Pneumocystis carinii pneumonia in 104 patients with AIDS.

We reviewed the initial and follow-up chest roentgenograms (CXR) of 104 patients with the acquired immune deficiency syndrome (AIDS) and Pneumocystis carinii pneumonia (PCP) diagnosed between 1981 and 1985 in order to determine the relative frequencies of its various roentgenographic patterns. Although a diffuse bilateral interstitial infiltrate is most common, it was concluded that unusual and atypical roentgenographic manifestations of PCP occur in AIDS. These include localized infiltrate, cystic or honeycomb lesions, hilar enlargement and spontaneous pneumothorax.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Persistence of Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome. Evaluation of therapy by follow-up transbronchial lung biopsy.

The effectiveness of therapy with trimethoprim-sulfamethoxazole and/or pentamidine has not been fully evaluated in AIDS patients with Pneumocystis carinii pneumonia (PCP). Since recurrence of PCP is common, follow-up lung biopsy (15 transbronchial, one open) was performed as part of the clinical evaluation of 16 episodes of PCP. All patients had shown evidence of clinical improvement during treatment and had received a mean duration of therapy of 17.6 days. In six of 16 episodes (38 percent), however, a repeat biopsy remained positive for PCP an average of 25.2 days after initial diagnosis. Retrospective comparison of standard clinical parameters (fever response, arterial blood gas results, roentgenographic characteristics) could not adequately distinguish episodes with positive follow-up biopsies from those with negative biopsies. Persistence of PCP after conventional treatment may be an important factor in recurrences of this infection in AIDS patients.

Acquired Immunodeficiency Syndrome↗