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Biomedical subjects

D Roden

Publications and source records attributed to D Roden.

15 recordsLinked to original sources
PubMed2001

Differential expression of KvLQT1 and its regulator IsK in mouse epithelia.

KCNQ1 is the human gene responsible in most cases for the long QT syndrome, a genetic disorder characterized by anomalies in cardiac repolarization leading to arrhythmias and sudden death. KCNQ1 encodes a pore-forming K+ channel subunit termed KvLQT1 which, in association with its regulatory beta-subunit IsK (also called minK), produces the slow component of the delayed-rectifier cardiac K+ current. We used in situ hybridization to localize KvLQT1 and IsK mRNAs in various tissues from adult mice. We showed that KvLQT1 mRNA expression is widely distributed in epithelial tissues, in the absence (small intestine, lung, liver, thymus) or presence (kidney, stomach, exocrine pancreas) of its regulator IsK. In the kidney and the stomach, however, the expression patterns of KvLQT1 and IsK do not coincide. In many tissues, in situ data obtained with the IsK probe coincide with beta-galactosidase expression in IsK-deficient mice in which the bacterial lacZ gene has been substituted for the IsK coding region. Because expression of KvLQT1 in the presence or absence of its regulator generates a K+ current with different biophysical characteristics, the role of KvLQT1 in epithelial cells may vary depending on the expression of its regulator IsK. The high level of KvLQT1 expression in epithelial tissues is consistent with its potential role in K+ secretion and recycling, in maintaining the resting potential, and in regulating Cl- secretion and/or Na+ absorption.

Animals↗
PubMed2000

Photocurrent measurements for laterally resolved interface characterization.

A miniaturized optical set-up based on a CD-ROM player optic was developed for LAPS (light addressable potentiometric sensors). A focus of 2.6 microm was achieved using this easy to handle device. The lateral resolution of LAPS measurements can be improved by using GaAs as the semiconductor material instead of Si. The diffusion length of the minority charge carriers was determined to be smaller than 3.1 microm. A new method called SPIM (scanning photo-induced impedance microscopy) is described. Using this technique, the impedance of thin films can be measured with lateral resolution.

Journal Article↗
PubMed1997

A review of 24 cases of Mohs surgery and ophthalmic plastic reconstruction.

PURPOSE: Mohs surgery (micrographically controlled excision) has been advocated as an effective method of dealing with infiltrative periorbital skin tumours. It has been shown to have high rates of tumour clearance with minimal loss of normal tissue, thus making oculoplastic reconstruction easier and functional preservation better. The aim of the present study was to confirm this. Guidelines for the selection of patients for Mohs surgery are discussed. METHODS: We retrospectively reviewed 24 cases of primary (n = 18) and recurrent (n = 6) periorbital basal and squamous cell carcinomas managed by Mohs micrographic excision and plastic reconstruction who presented to the Royal Perth Hospital between 1992 and 1996. RESULTS: Our high rate of tumour clearance (100%) was similar to that of previous studies, although our follow-up period was only 14.6 months. The fact that 50% of our patients with lid involvement had an intact posterior lamella after Mohs excision correlates with the high level of normal tissue preservation. The low rate of postoperative symptomatic problems suggests good maintenance of function. The infiltrative nature of these tumours was highlighted by the substantial proportion of cases (37.5%) that had a much larger excision defect than what was expected prior to excision. CONCLUSIONS: Our analysis confirms that Mohs excision and subsequent oculoplastic reconstruction is an effective method to use when managing periorbital infiltrative skin tumours.

Adult↗
PubMed1996

Outcome of residual cholesteatoma and hearing in mastoid surgery.

OBJECTIVE: To review 12 years of the senior author's experience with mastoid surgery for cholesteatoma. DESIGN: Retrospective review. SETTING: Northwestern University Medical School. METHODS: Available records included 97 mastoid procedures for cholesteatoma: 54 with intact canal-wall and 43 canal-wall-down. MAIN OUTCOME MEASURES: Residual cholesteatoma, pure-tone audiometry, and speech audiometry were compared for both groups. RESULTS: Residual disease rate was 11 of 54 (20%) for intact canal-wall procedures and 2 of 43 (5%) for canal-wall-down procedures. Average follow-up was 2 years. Hearing was preserved postoperatively, and neither procedure demonstrated clear superiority in this regard. CONCLUSION: While canal-wall-down mastoidectomy provides a lower residual disease rate with equal hearing outcome, the role of intact wall mastoidectomy remains a viable choice in certain clinical situations.

Adult↗
PubMed1992

Prognostic significance of ventricular premature depolarizations measured 1 year after myocardial infarction in patients with early postinfarction asymptomatic ventricular arrhythmia.

OBJECTIVES: The objective of this study was to examine the relation between death and the frequency of premature ventricular depolarizations measured approximately 1 year after myocardial infarction. BACKGROUND: The reported association between premature ventricular depolarizations and death in the weeks after myocardial infarction is in part the basis for the use of antiarrhythmic drugs. Such an association has not been reported on for observations obtained at a much greater interval after myocardial infarction. METHODS: We examined the association between mortality and premature ventricular depolarization rates measured 1 year after myocardial infarction in patients with asymptomatic ventricular arrhythmia early (between 6 and 90 days, median 28) after infarction, as measured by 24-h ambulatory electrocardiographic recording. The study group consisted of 502 patients enrolled in the Cardiac Arrhythmia Pilot Study during 1983 to 1985. They were followed up during the course of the study and subsequently by a National Death Index search (average follow-up interval 1,080 days). RESULTS: Death was recorded for 87 patients through 1987. Because patients were admitted to the Cardiac Arrhythmia Pilot Study only if they had greater than or equal to 10 ventricular premature depolarizations/h, the arrhythmia rate measured at baseline (that is, early after infarction) was not expected to, and did not, predict mortality. In 360 patients ventricular premature depolarization rates were measured approximately 1 year from their index myocardial infarction while they were not receiving antiarrhythmic therapy. In these patients, who had survived 1 year after the index infarction, the rate of ventricular premature depolarizations/h measured 1 year after infarction was highly predictive of subsequent death (p less than 0.001). Recent heart failure and a history of diabetes mellitus were also strongly predictive of death. CONCLUSION: The prognostic value of ventricular premature depolarizations observed 1 year after a myocardial infarction may be significant even in a sample selected for frequent ventricular premature depolarizations observed early after the event.

Arrhythmias, Cardiac↗
PubMed1992

Angiotensin II facilitates tricyclic antidepressant-induced changes in QRS-duration in the rat.

Experimental evidence indicates that angiotensin II can modulate sodium channel and gap junction function. This raises the possibility that variations in angiotensin II could alter the effect of drugs that act on these mechanisms. In this study, the influence of changing salt status and angiotensin II activity has been investigated by evaluating the QRS prolonging effects of the sodium channel blocking drug, desmethylimipramine. In control rats with a normal salt intake, intravenous infusion of desmethylimipramine (0.8 mg/kg/min) over 60 min increased QRS duration over time to 150% of control by 60 min; mean arterial blood pressure and pulse rate were decreased. In salt-deplete rats, the response to desmethylimipramine was similar to controls for 30 min. Thereafter, QRS duration increased more rapidly than controls. In rats on a high salt diet, the same desmethylimipramine infusion produced no change in QRS duration for 30 min, despite equivalent reductions in mean arterial blood pressure. Thereafter, QRS duration increased, reaching values similar to control by 60 min. In rats on a normal salt diet pretreated with captopril, there was a similar blunting of the QRS response to desmethylimipramine to that observed in salt-loaded rats. The QRS response to desmethylimipramine and salt-loaded rats on normal salt diets receiving captopril returned to the control pattern after a subpressor infusion of angiotensin II (3 ng/min), while a higher rate of angiotensin II (10 ng/min) further enhanced the QRS prolonging effect of desmethylimipramine. These data demonstrate that endogenous angiotensin II contributes to the regulation of the cardiac electro-physiological response to DMI.

Angiotensin II↗
PubMed1990

Delayed radiation injury to the retrobulbar optic nerves and chiasm. Clinical syndrome and treatment with hyperbaric oxygen and corticosteroids.

Thirteen patients with delayed radiation injury to the optic nerves and chiasm were treated with hyperbaric oxygen (HBO) and corticosteroids. These patients experienced painless, abrupt loss of vision in one (6 patients) or both (7 patients) eyes between 4 and 35 months after receiving radiation doses of at least 4500 cGy to the region of the chiasm. Diagnostic evaluation including neuro-imaging and lumbar puncture showed no recurrent tumor and no other cause for visual loss. No patient's vision improved during treatment or follow-up lasting between 1 and 4 years. There were no serious complications of treatment.

Adrenal Cortex Hormones↗
PubMed1990

Pulsed high frequency (27MHz) electromagnetic therapy for persistent neck pain. A double blind, placebo-controlled study of 20 patients.

In the majority of patients with neck pain, symptoms will resolve spontaneously or quite quickly in response to therapy. However, some patients' symptoms persist for a long period, irrespective of therapy. In this study, 20 patients with persistent (greater than 8 weeks) neck pain were enrolled in a double blind, placebo-controlled trial of low energy, pulsed electromagnetic therapy (PEMT)--a treatment previously shown to be effective in soft tissue injuries. For the first 3-week period, group A (10 patients) received active PEMT units while group B (10 patients) received facsimile placebo units. After 3 weeks, both pain (visual analogue scale (P less than .023) and range of movement (P less than .002) had improved in the group on active treatment compared to the controls. After the second 3 weeks, during which both groups used active units, there were significant improvements in observed scores for pain and range of movement in both groups. PEMT, in the form described, can be used at home easily in the treatment of patients with neck pain. It is frequently successful and without side effects.

Adult↗
PubMed1989

A serial study of anticardiolipin antibody and antimitochondrial antibody type M5 in a patient with polyarthritis and polymyositis.

A 22-year-old female presented with polyarthritis and subsequent polymyositis. Initially, she had moderately high levels of anticardiolipin (aCl) and antimitochondrial antibody (AMA) type M5. Following corticosteroid therapy, the anticardiolipin antibody rapidly fell to background levels but reappeared with the onset of two significant clinical events.

Adult↗
PubMed1989

Purtscher's retinopathy and fat embolism.

A 19-year-old woman who sustained multiple trauma but no head injury developed fulminant fat embolism syndrome (FES). Her neurological deterioration was associated with cerebral oedema and the concomitant Purtscher's type retinopathy. We suggest that the pathogenesis of the retinopathy and of the cerebral oedema are the same and that Purtscher's retinopathy and retinopathy of the FES are indistinguishable.

Adult↗
PubMed1987

Anticardiolipin antibodies in rheumatoid arthritis.

Anticardiolipin antibody (ACA) was present in the sera of 49% of 90 consecutive patients with rheumatoid arthritis (RA). The ACA was absent in 30 control patients with osteoarthritis. C-reactive protein levels equal to or exceeding 7 mg/dl were found in 10 patients all of whom were ACA positive. ACA was present in a larger proportion of rheumatoid factor (RF) positive than of RF negative patients. Male sex and extra-articular manifestations of RA were both more common in ACA positive than ACA negative patients. In the ACA positive group the lupus anticoagulant and VDRL tests were negative. However, a small number of patients had evidence of vascular events.

Adult↗
PubMed1987

A five-year survey of ocular shotgun injuries in Ireland.

Between November 1980 and September 1985 20 patients in Ireland sustained accidental ocular shotgun injuries severe enough to necessitate hospital admission. Eight patients had contusion injuries and 12 perforating injuries. Contusion damage was disproportionate to the size of the pellet. Through and through perforation of the globe occurred in eight patients; the remaining four patients in this group had retained intraocular pellets. Twelve patients sustained perforating eye injuries. Those that were treated by primary closure alone lost the sight in that eye. Those treated by vitreoretinal surgery recovered vision directly related to where the pellet had its exit from the eye. It was possible to contact 15 of the patients. All 15 were shooting pheasant. It was not possible to relate the distance of the patient from the gun to the severity of the ocular injury.

Adolescent↗
PubMed1987

A training procedure for immunization.

A booklet on child immunization and a training procedure using a video have been developed in a health authority. The initiative has proven highly acceptable and has resulted in a demonstrable increase in professional knowledge and in vaccine uptake. Further initiatives are described.

Child↗
PubMed1984

Pharmacology, electrophysiology, and pharmacokinetics of mexiletine.

Mexiletine is a class I antiarrhythmic agent that is active after both oral and intravenous administration and similar in structure and activity to lidocaine. It decreases phase O maximal rate of depolarization (Vmax) by fast sodium channel blockade. The marked rate dependence of Vmax depression may explain mexiletine's lack of effect on normal conduction and its efficacy against ventricular tachyarrhythmias. Mexiletine significantly decreases the relative refractory period in His-Purkinje fibers without changing the sinus rate or atrioventricular and His-Purkinje conduction times. Action potential duration is usually shortened. Mexiletine may aggravate preexisting impairment of impulse generation and conduction. Uptake and distribution of mexiletine are rapid, systemic bioavailability is about 90%, and tissue distribution is extensive. Mexiletine is primarily metabolized in the liver; 10% to 15% is excreted unchanged in the urine. Elimination half-life is 9 to 11 hours after intravenous or oral administration. Microsomal enzyme induction shortens mexiletine's elimination half-life, whereas hepatic disease and acute myocardial infarction prolong it. Renal disease has little effect, although hemodialysis increases mexiletine clearance. Plasma concentrations from 0.75 to 2.0 mg/L are usually associated with a desirable therapeutic response.

Absorption↗