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Biomedical subjects

L O'Connor

Publications and source records attributed to L O'Connor.

71 records · Page 4Linked to original sources
PubMed1982

Rapid loss of delta-aminolevulinic acid dehydratase activity in primary cultures of adult rat hepatocytes: a new model of zinc deficiency.

Nonproliferating cultures of adult rat hepatocytes were found to lose 60-70% of cell-associated zinc during their first 24 h of incubation in standard, serum-free medium. The loss of zinc was accompanied by a profound loss (greater than 95%) in the activity of the zinc metalloenzyme, delta-aminolevulinic acid dehydratase, as well as a loss (greater than 85%) in the cellular content of immunoreactive delta-aminolevulinic acid dehydratase protein. Restoration of cellular zinc content by the addition of zinc to the culture medium partially prevented the losses of both delta-aminolevulinic acid dehydratase activity and immunoreactive protein. Since the spontaneous, selective loss of cellular zinc appears to have specific effects on a relevant hepatic function, this culture system constitutes a novel in vitro model of zinc deficiency in mature liver.

Animals↗
PubMed1981

Intracoronary thrombolysis in evolving myocardial infarction.

After experimental studies in dogs confirmed the feasibility and safety of rapid intracoronary thrombolysis by local infusion of Thrombolysin (streptokinase and plasmin), intracoronary thrombolysis was attempted in 20 patients with evolving myocardial infarction who were hospitalized within 3 hours from the onset of symptoms during the day and within 2 hours at night. Thrombolysin was infused in the immediate vicinity of the site of coronary occlusion using a 0.85 mm outer diameter catheter advanced through the lumen of the Judkins catheter. Reperfusion was achieved in four patients after an average of 43 minutes of Thrombolysin infusion at a rate of 2000 IU/min and in 15 patients after an average of 21 minutes of Thrombolysin infusion at a rate of 4000 IU/min. The failure to open the artery in one patient may have been caused by our inability to advance the infusion catheter close to the site of occlusion. Rethrombosis occurred in one patient 8 days after reperfusion and 2 days after discontinuation of anticoagulants because of a history of chronic alcoholism. Wall motion and perfusion studies showed improvement following reperfusion. Patency of the artery was achieved an average of 4 hours after the onset of symptoms. The need for earlier reperfusion is emphasized.

Adult↗
PubMed1981

Short-term memory in deaf children in relation to verbal and dactylo-kinesthetic encoding.

The present study addressed the question, "To what extent does nonstrategic verbal encoding differ in deaf and normally hearing children?" With the use of a probe-type serial memory task, hearing and deaf children matched on chronological age, IQ, and sex were randomly assigned to named, unnamed, or dactylo-kinesthetic (fingerspelled) stimulus pretraining conditions and compared on subsequent serial recall performance. Strong primacy effects were found even though children could not use overt cumulative rehearsal. Analysis of d' scores found no difference between hearing or deaf children on pretrained named instruction; overall inferior recall occurred for deaf children on unnamed condition. Results were interpreted in terms of comparable nonstrategic processes in deaf children that occur prior to the application of mnemonic strategies.

Child↗
PubMed1978

Giant intracranial aneurysms simulating brain neoplasms on computed tomography.

Giant intracranial aneurysms (GIA) may simulate brain neoplasms on computed tomography (CT) scans. We present three cases in which a GIA was mistakenly diagnosed as a brain neoplasm on the basis of CT findings. The correct diagnosis was made in each case by cerebral angiography. The possibility of GIA must be considered when a nonenhanced CT study shows a well circumscribed mass without edema at the base of the brain and contrast infusion reveals homogeneous or inhomogeneous enhancement.

Adult↗
PubMed1978

Unscheduled DNA synthesis induced by procarcinogens in suspensions and primary cultures of hepatocytes on collagen membranes.

Unscheduled DNA synthesis was induced by procarcinogens in freshly isolated suspensions and primary cultures (6 days old) of hepatocytes on collagen membranes. Incorporation of [3H]thymidine in the presence of hydroxyurea was used to measure unscheduled DNA synthesis. When hepatocellular DNA was isolated on cesium chloride gradients, significant levels of unscheduled DNA synthesis were measured. Similar concentrations of procarcinogens elicited higher levels of unscheduled DNA synthesis in hepatocellular suspensions than in primary cultures. The results demonstrate that hepatocytes cultured on collagen membranes can metabolize chemical carcinogens. Suspensions of freshly isolated hepatocytes, however, are more active in procarcinogen metabolism than are those of primary cultures. The selective advantages of the two systems of hepatocytes can be utilized for the establishment of short-term in vitro screening systems of mutagens and carcinogens.

2-Acetylaminofluorene↗
PubMedDate not supplied

The drug-of-choice phenomenon: why addicts start using their preferred drug.

The reasons why addicts begin using their preferred drug are examined and compared for differences between groups. Utilizing a questionnaire regarding their drug of choice and their reasons for use, a survey was made of 130 subjects (88 men and 42 women; mean age = 34.3 years) who were actively involved in recovery programs. The most frequent period of abstinence from the use of alcohol and other drugs was between one and two years. Forty-five of the subjects preferred opioids, 27 amphetamines, 24 cocaine, 18 marijuana, and 16 alcohol. The reasons for use were separated into three categories: emotional, physical, and social. Results showed that the amphetamine and cocaine addicts selected a higher number of physical reasons for use, and that the alcohol group chose social reasons most frequently. There were no differences between drug groups in total number of emotional reasons selected. Specific reasons for use were also analyzed between drug-of-choice groups. The findings cast doubt on earlier studies that suggested differential psychopathology or emotional disorders among addicts with different drugs of choice. Clinical implications of these data are discussed.

Adolescent↗
PubMedDate not supplied

There's a worm in my eye.

OBJECTIVE: To report a case of an unusual worm infestation of the eye. CLINICAL FEATURES: A 28-year-old veterinary surgeon complained of the intermittent appearance of a worm in her eyes. Her previous camping travels in west and central Africa suggested the diagnosis of Loa loa, which was confirmed on surgical removal of the worm from beneath the conjunctiva. Laboratory investigations showed peripheral blood eosinophilia, negative thick blood film examinations for microfilariae and positive results of filarial serology. INTERVENTION AND OUTCOME: The worm was removed intact after incision of the overlying conjunctiva. Diethylcarbamazine was prescribed and the patient remained asymptomatic in the subsequent 12 months. CONCLUSIONS: The sighting of a worm in the eye is rare in Australia and usually occurs in immigrants or returned travellers. Loa loa is the most common offending species and is identifiable and treatable.

Adult↗
PubMedDate not supplied

Acquired left coronary artery to left atrium fistula: unusual complication of aortocoronary bypass.

This report describes a very unusual complication of aortocoronary bypass graft surgery. It consists of the formation of an acquired fistula between the left circumflex coronary artery and the left atrium in a patient who was operated two years prior to its clinical presentation. Significant coronary steal gave rise to disabling angina and prompted a second operation to close the fistula. The diagnosis was made with selective arteriogram that clearly delineated the fistulous tract and surgery was accomplished without extracorporeal circulation.

Coronary Angiography↗