Biomedical subjects

C Bolger

Publications and source records attributed to C Bolger.

26 records · Page 2Linked to original sources

PubMed1995

Elevated levels of lipoprotein (a) in association with cerebrovascular saccular aneurysmal disease.

The relationship between cerebrovascular aneurysmal disease and atherosclerosis remains unclear. Elevated serum levels of lipoprotein (a) (Lp[a]), are an independent risk factor for atherosclerosis. We measured serum Lp(a) levels in 50 patients who had angiographically proven saccular aneurysmal disease and who were free of clinically significant atheromatous disease (as judged by their medical histories and the results of physical examination, electrocardiography, and carotid angiography). The Lp(a) serum levels in these patients were compared with the Lp(a) serum levels in a group of 42 normal healthy controls. Serum Lp(a) levels in the patients was 20.1 +/- 0.42 mg/dl (median +/- standard error); however, median serum Lp(a) in the control subjects was 10.8 +/- 0.47 mg/dl (P < 0.01). Among females, the difference in serum Lp(a) levels was significant; the levels were 22.2 +/- 0.6 for female patients (n = 29) and 9.5 +/- 0.53 in female control subjects (n = 26) (P < 0.005). The most significant difference (P < 0.002) was seen in females < 50 years old (14 patients, 10 control subjects). No significant differences were seen in the Lp(a) serum levels between 21 male patients and 16 male control subjects. Lp(a) levels above the threshold level (30 mg/dl) were found in 20 patients and 7 control subjects (chi 2 = 5.99, P < 0.02); 12 female patients and 3 female control subjects (chi 2 = 6.16, P < 0.02; 8 male patients and 4 male control subjects (this difference was not significant). These results indicate either that cerebrovascular aneurysmal disease and subclinical atherosclerosis are related or that Lp(a) is a risk factor for vasculopathies other than atheroma.

Adult↗

PubMed1994

Sources of variance in ocular microtremor.

This study presents a preliminary investigation of the sources of variance in the measurement of ocular microtremor frequency in a normal population. When the results from both experienced and relatively inexperienced operators are pooled, factors that contribute significantly to the total variance include the measurement procedure (p < 0.001), day-to-day variations within subjects (p < 0.001), and inter-subject differences (p < 0.01). Operator experience plays a role in determining the measurement precision: the intra-subject coefficient of variation is about 5% for a very experienced operator, and about 14% for a relatively inexperienced operator.

Adult↗

PubMed1993

Ocular microtremor measurement system: design and performance.

The frequency of ocular microtremor (OMT) is related to the functional status of the brain stem, and thus OMT may be useful in the diagnosis and management of brain stem disorders. The paper discusses the design of an OMT measurement system and reports quantitative specifications for three portable systems. All systems use a piezo-electric element as the transducer, which measures the displacement of the sclera during eye rotations. The systems differ in the manner in which the signal is recorded. All systems can detect eye movements corresponding to displacements of the sclera ranging from 12 to over 3000 nm. The frequency responses of all systems are flat (< 2 dB deviation from peak response) between 20 and 150 Hz. The phase response shows deviations (< pi) at the extremes of this range, but qualitative comparison of input and measured signals demonstrates that phase distortion is not excessive. Thus all systems are acceptable for clinical studies involving OMT.

Biomedical Engineering↗

PubMed1992

High frequency eye tremor: reliability of measurement.

Recent reports suggest that high frequency eye tremor or ocular microtremor (OMT) may be a useful indicator of brainstem function. The method of record analysis, and in particular the amount of record subjected to such analysis, has varied widely. We have recorded OMT from 10 normal subjects. Using these records we have performed 42 distinct replication reliability studies. We suggest seven parameters of OMT (including overall frequency of tremor) which may be of value in comparing abnormal with normal records. For each parameter we have determined the optimal duration of the record to analyse and the reliability of such analysis. Our results suggest that at least 5 s of OMT should be analysed to yield an acceptable estimate of all seven parameters.

Adult↗

PubMed1991

Chylothorax after oesophagectomy.

Chylothorax is an uncommon complication of oesophagectomy. In a review of 537 oesophageal resections there were 11 cases of chylothorax, an incidence of 2.0 per cent. There was no correlation with site, size, penetration, lymph node status, length or type of tumour but there was a significant correlation between chylothorax and the type of operative procedure carried out. The incidence in 95 transhiatal resections was 10.5 per cent. The incidence following 442 transthoracic procedures was 0.2 per cent (P less than 0.001) with one chylous fistula occurring after a three-stage oesophagectomy. Initial management was conservative with chest drainage and total parenteral nutrition. Thoracotomy and duct ligation was subsequently carried out in three patients and was successful in two. The third patient died. Conservative management alone was successful in four out of eight patients, with closure of the fistula at a median of 35 days (range 14-42 days). Four patients treated conservatively died. Transhiatal oesophagectomy greatly increases the risk of chylothorax, a condition that carries a high mortality rate (46 per cent in this series) whether managed conservatively or by surgical intervention.

Chylothorax↗

PubMed1985

Survey of student opinion of the medical curriculum at Trinity College, Dublin, Republic of Ireland.

This description of a survey is not intended to give a blow-by-blow account of what was found or the significance of the result, since this would only be of any relevance to the medical school in which the survey was conducted. Rather it is intended to give a description of what was done and why it was done, for medical students in other schools who wish to conduct a similar inquiry. The initial indication that a survey was required was the establishment in the medical school of a curriculum review group. It was felt that rather than airing the group's own views, or impressions of what other students' views were, it would be advisable to find out exactly how students felt. To this end the survey was conducted.

Attitude of Health Personnel↗

PubMed1985

Effect of hematoporphyrin derivative photoradiation therapy on survival in the rat 9L gliosarcoma brain-tumor model.

Intracerebral tumors were produced in 99 rats by stereotaxic implantation of 9L gliosarcoma brain-tumor cells. Hematoporphyrin derivative (HPD), 10 or 20 mg/kg, was administered as an intravenous bolus 24 or 48 hours before irradiation of the tumor region with light from an argon pumped-dye laser (632 nm). Laser light, at a dose of 30, 60, or 200 joules/sq cm, was delivered through a craniectomy 10 or 13 days after tumor implantation. Survival times were significantly prolonged in rats exposed to laser light at a dose of 200 joules/sq cm 24 hours after administration of HPD, 20 mg/kg.

Animals↗

PubMed1983

Evoked potentials in rats with misonidazole neurotoxicity. I. Brain stem auditory evoked potentials.

Central neurotoxicity produced in rats by daily administration of 300 mg/kg of misonidazole (MISO) 5 times/week for 4-5 weeks (total dose = 6.0 gm/kg) was evaluated weekly wit brain stem auditory evoked potentials (BAEPs). Compared to untreated control rats, all treated rats had a prolongation of the I-IV interpeak latency (p less than 0.005) at a mean of 13.2 +/- 2.7 days at a cumulative dose of approximately 4.0 gm/kg of MISO per rat. In some rats, the I-III and I-II interwave latencies were prolonged and waves III and IV were lost. Control rats did not show any significant alteration in BAEP latency or amplitude. Histopathologic examination of the brain stems of treated rats showed that necrotic lesions were present primarily in the nuclei of the tegmentum of the fourth ventricle, with scattered nuclear involvement in the cerebellar roof nuclei, inferior olive, and nucleus of the spinal tract of the trigeminal nerve. The cerebral cortex appeared to be normal in all treated rats. Changes in BAEPs caused by central neurotoxicity correlated with the histopathologic findings. We conclude that BAEPs are a sensitive method for evaluating MISO central neurotoxicity in the rat model.

Animals↗