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Biomedical subjects

P Logan

Publications and source records attributed to P Logan.

36 records · Page 2Linked to original sources
PubMed1996

Absent meibomian glands: a marker for EEC syndrome.

A patient with a 20 year history of severe keratoconjunctivitis of unknown origin was found, on assessment at a blepharitis clinic, to have complete absence of meibomian glands. Further examination revealed the features of EEC syndrome. To our knowledge, this is the only case to have been diagnosed in this way. The ocular complications of EEC syndrome and other ectodermal dysplasias are reviewed.

Abnormalities, Multiple↗
PubMed1995

Convergence substitution for paralysed horizontal gaze.

Three patients with paralysed horizontal gaze are presented. Involuntary use of convergence to assist horizontal gaze was noted as a late feature. All patients showed (1) unilateral or bilateral horizontal gaze palsy (two patients had one and a half syndrome, the other had bilateral nuclear sixth nerve palsies), (2) adduction of both eyes on attempted gaze into the paralysed field, (3) miosis which coincided with adduction. Convergence substitution should be considered in the differential diagnosis of gaze induced strabismus.

Accommodation, Ocular↗
PubMed1995

Strength and power assessment. Issues, controversies and challenges.

Athletic strength and power refer to the forces or torques generated during sporting activity. Their assessment can be used for strength diagnosis or talent identification, to monitor the effects of training interventions and to estimate the relative significance of strength and power to particular athletic pursuits. However, strength and power assessment is a difficult task. Reasons for this include: the fledgling status of research within the area, our limited understanding of the mechanisms underpinning strength and power performance and development, and limitations associated with various forms of dynamometry. This article describes a frame work for the collection of data which may ultimately lead to recommendations for the assessment of strength and power in sporting contexts. Such a framework will be evolutionary and depends upon synergistic improvements in our understanding of: the physiological mechanisms underpinning strength and power development; the effect that various training regimens have upon the development of strength and power; and factors influencing the validity and reliability of dynamometry. Currently, isometric, isoinertial and isokinetic dynamometry are employed in assessment. Each form has its supporters and detractors. Basically, proponents and critics of isokinetic and isometric dynamometry emphasis their apparently high internal and apparently low external [corrected] validity respectively. While the converse applies for isoinertial dynamometry. It appears that all 3 modalities can have acceptable reliability, however this should be established rather than assumed, as the reliability of each can be threatened by a number of considerations (e.g. instruction for isometric tasks, the impact of weight used during weighted jumping tasks, and the effects of gravity and feedback on isokinetic performance). While reliability is a seminal issue in assessment, it is not the only critical issue. Specifically, there has been little research into the correlation between strength and power measures and athletic performance. This work is central to the use of such indices in talent identification. To date, this work has generally been limited to heterogeneous rather than homogeneous groups. More work is required in this area. Furthermore, not all modes of assessment are sensitive or similarly sensitive to various training interventions. This suggests that these modalities are measuring different neuromuscular qualities. How these qualities relate to performance requires more work, and will determine the contexts in which various strength and power assessment modalities and protocols are used.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMed1995

Assessment of the cytotoxicity of the photosensitizing drug BPD verteporfin using human vascular smooth muscle cells in culture.

Photosensitizing drugs are selectively taken up by lipid-rich lesions such as atheromatous plaque which when exposed to light render the drugs cytotoxic. However, skin photosensitivity which persists for many weeks is a significant side effect. We investigated the cytotoxicity of a new photosensitizing drug, the benzoporphyrin derivative BPD verteporfin (Quadra Logic Technologies), which does not have this deleterious side effect. Vascular smooth muscle cells (VSMC) from normal human mammary and diseased human coronary arteries were grown in culture from explants and characterized with respect to their growth rates. The sensitivity to BPD with and without light was assessed by measuring viability after treatment. The lethal dose of drug for 50% viability loss (LD50) for BPD with light was approximately 12.5 ng/ml for mammary artery, with 52 +/- 8% cell survival (n = 6). The coronary artery VSMC from all patient sources, although differing significantly in growth rate, had a survival of 44 +/- 6% (n = 12) at the same concentration of BPD used for the mammary artery SMC (p = NS). Our results established the LD50 for BPD using human arterial sources of SMC and showed that the growth rates of the cells did not affect the cytotoxicity of the drug.

Cell Survival↗
PubMed1991

Transesophageal echocardiographic evaluation for mural thrombus following radiofrequency catheter ablation of accessory pathways.

BACKGROUND: Catheter ablation of accessory pathways (APs) provides a definitive therapy for patients with Wolff-Parkinson-White Syndrome. The reported incidence of thrombus formation on ablation-induced injuries with direct current shock varies from 0%-20% in animal studies. The purpose of this study was to determine the prevalence of mural thrombus following catheter ablation with radiofrequency current of accessory pathways in humans. METHODS AND RESULTS: Radiofrequency current (30-35 watts) was applied through a catheter electrode placed against the mitral or tricuspid annulus guided by catheter recordings of AP potentials. Transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 95 of 111 patients, at 18 +/- 6 hours following catheter ablation. After ablation, no thrombus was identified at or near the ablation site in any patient. Two out of 95 patients had a mural thrombus at a remote site that was detected by TEE but not by TTE. No new wall motion abnormality was detected in any patient. No significant regurgitant valvular lesion was found in any patient. CONCLUSION: Intracardiac thrombus was not identified at the site of catheter ablation, possibly owing to the small lesions produced by radiofrequency energy and high blood flow normally present in those areas. However, patients may be at small risk for mural thrombus at a remote site from prolonged placement of catheters.

Adult↗
PubMed1991

Intermittent downbeat nystagmus secondary to vermian arachnoid cyst with associated obstructive hydrocephalus.

A 27-year-old man presented with a history of dizziness and intermittent vertical oscillopsia after oblique extension of the head and neck, following a neck injury 2 years previously. He had no other symptoms of cerebellar or brainstem dysfunction. On examination, an intermittent downbeat nystagmus lasting about fifty seconds was elicited by head extension and rotation. Radiologic examination showed slight lateral instability of the odontoid on lateral rotation, and computed tomography brain scan with Iopamidol 300 (Niopam) contrast revealed a 5-cm vermian arachnoid cyst in the posterior fossa with obstructive hydrocephalus. Removal of the cyst cured the nystagmus.

Adult↗
PubMed1985

Randomised double-blind trial of acyclovir (Zovirax) and adenine arabinoside in herpes simplex amoeboid corneal ulceration.

Fifty-one patients were treated in a dual-centre, double-blind comparison of acyclovir and adenine arabinoside in herpetic amoeboid (geographic) corneal ulceration. Twenty-four of the 25 patients receiving acyclovir healed in a mean time of 12.2 days, while 24 of the 26 patients treated with adenine arabinoside healed in a mean time of 11.0 days. There was no statistically significant difference between the two groups in terms of healing. A second analysis, excluding any patients who had received antiviral treatment immediately prior to entry into the study, showed that 18 of the 19 who received acyclovir healed in an average of 11.7 days and 18 of the 19 recipients of adenine arabinoside healed in a mean time of 11.2 days. Again the difference was not statistically significant.

Acyclovir↗
PubMed1983

Acyclovir (Zovirax) in herpetic disciform keratitis.

Forty patients with disciform keratitis were randomly assigned to double-blind treatment with 3% acyclovir and 0.01% betamethasone drops or acyclovir and matching placebo. All patients who received the combination healed in a median time of 21 days, while 11 of 19 patients who received acyclovir alone were withdrawn because their condition remained static or worsened (p less than 0.001). The combination therapy produced a faster rate of healing (p = 0.004); other clinical parameters also improved more favourably in the combination treatment group. Three patients had mild transient punctate keratopathy, but no serious adverse effects were seen despite treatment for a median duration of 28 days in the acyclovir group and 38 days in the combined therapy group. A combination of acyclovir and dilute steroid drops is effective in the management of disciform keratitis.

Acyclovir↗
PubMed1983

Comparison of the efficacy and toxicity of acyclovir and of adenine arabinoside when combined with dilute betamethasone in herpetic disciform keratitis: preliminary results of a double-blind trial.

Acyclovir is an effective and relatively non-toxic antiviral agent which has recently been introduced for the treatment of herpes virus infections in man. When combined with dilute steroid, acyclovir heals herpetic disciform keratitis and preliminary results of a double-blind clinical trial suggest that it may be more effective and less toxic than adenine arabinoside in the treatment of this condition.

Acyclovir↗
PubMed1983

Laser trabeculoplasty in the pseudo-exfoliation syndrome.

Because of the high incidence of pseudo-exfoliation in Ireland and because of the difficult problem this group poses regarding control it was decided to treat a group of these patients with the Argon Laser. This paper is a preliminary report of our experience.

Glaucoma↗
PubMed1982

Acyclovir in herpes keratitis.

Herpes simplex keratitis accounts for 50 percent of patients presenting at our corneal clinic. Studies of the use of acyclovir in dendritic and geographic ulceration and disciform keratitis are presented. In a double-blind study of acyclovir and idoxuridine in 60 patients with dendritic keratitis, acyclovir was shown to be superior and produced no serious side effects. Patients with geographic ulcers have been treated on an open basis with acyclovir and the drug was found to be effective. A combination of acyclovir and dilute steroid drops appeared to be as effective as currently available treatments in the management of disciform keratitis. Double-blind studies are now in progress to evaluate acyclovir in geographic and disciform keratitis.

Acyclovir↗