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Biomedical subjects

D J Connor

Publications and source records attributed to D J Connor.

25 records · Page 2Linked to original sources
PubMed1983

Plasma and myocardial levels of cefonicid during open-heart surgery.

To minimize the incidence of postoperative infections in patients undergoing open-heart surgery, antibiotics should maintain tissue concentrations greater than the minimal inhibitory concentration (MIC) for potential pathogens (eg, Staphylococcus) for the duration of the operation. The ability of cefonicid, a new β-lactamase-resistant parenteral cephalosporin, to attain plasma and myocardial levels greater than the MIC (4.8 to 5.0 μg/mL) for penicillin-resistant Staphylococci was assessed in 13 patients. Six patients were administered 1 g and seven patients were administered 2 g of cefonicid IM one hour prior to surgery. In all patients the plasma concentrations of the drug were determined at the start of surgery, 15 minutes after the patient was placed on cardiopulmonary bypass (CPB), and at the completion of CPB. In addition, the concentration of cefonicid was determined in a right atrial biopsy. It was found that both 1 g and 2 g of cefonicid administered one hour prior to surgery resulted in plasma and myocardial levels greater than the MIC for the organisms most frequently implicated in postoperative infections.

Aged↗
PubMedDate not supplied

Solvent effects on beta protein toxicity in vivo.

Human beta (1-40) and rat beta (1-42) were dissolved in three different solvents and stereotaxically injected into rat hippocampus with the contralateral side injected with control reverse sequence peptide or vehicle alone. Results at 1 week showed gross toxicity of the 35% acetonitrile solvent which was markedly enhanced by 3 nmol of beta protein but not by reverse sequence peptide. Beta peptide in water also appeared more toxic than reverse sequence, but the results were less clear cut. In contrast, 3 nmol of beta peptide in a cyclodextrin/PBS solution produced no marked short-term toxic effects. Peripheral injection of substance P failed to prevent toxicity. We conclude that solvent effects play a major role in acute beta protein neurotoxicity.

Amyloid beta-Peptides↗
PubMedDate not supplied

Effects of NBm lesions on T-maze performance and thalamic biochemistry.

Fisher 344 rats underwent bilateral nucleus basalis magnocellularis (NBm) lesioning followed by testing in a delayed nonmatching-to-sample T-maze task. Both lesion and control animals acquired the task although the NBm animals were mildly impaired on acquisition and on trials to criterion. Increasing the delay reduced accuracy of performance equally in both groups. The NBm lesion did not alter the level of several thalamic amino acids. These data indicate that NBm lesioning does not produce a significant impairment in working or reference memory in this task and supports the hypothesis that NBm lesioning impairs attention.

Amino Acids↗
PubMedDate not supplied

Lack of long-term effects after beta-amyloid protein injections in rat brain.

Rat beta(1-42) peptide (beta/A4) or phosphate buffered saline (PBS) was bilaterally injected into the hippocampus (HIP) or the lateral ventricle (ICV) of 3-month-old Fischer-344 rats. Fifteen months later, the animal's ability to learn a spatial memory task was tested using the Morris water maze. Acquisition of the task was impaired by the bilateral injection of either peptide or PBS into the hippocampus. Hippocampal-injected animals showed an increased average latency to find the platform by approximately 6 s (p < 0.05). However, injection of rat beta-peptide into the hippocampus or lateral ventricles failed to induce behavioral impairment when compared to vehicle injected controls. Retention of this task was not significantly impaired in any group. The spatial acuity test, a trial without the platform, revealed that both groups of animals that received hippocampal injections were impaired, spending 23% less time in the target quadrant compared to ICV-injected animals (p < 0.005). Hippocampal ChAT activity was decreased in beta/A4-injected animals but not significantly (p < 0.06). beta/A4-immunoreactivity was detected at the bottom of the needle track and the adjacent parenchyma of beta/A4 hippocampal-injected animals after 16 months. However, long-term in vivo deposition of beta/A4 in both regions did not result in an upregulation of hippocampal amyloid precursor protein (APP) expression and there was no qualitative neuronal loss in the hippocampus.(ABSTRACT TRUNCATED AT 250 WORDS)

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