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Biomedical subjects

K Farrell

Publications and source records attributed to K Farrell.

At least 91 records · Page 5Linked to original sources
PubMed1986

Free and total serum valproate concentrations: their relationship to seizure control, liver enzymes and plasma ammonia in children.

The relationships between total and free serum valproate (VPA) concentrations and seizure control, serum liver enzyme activity and plasma ammonia concentration were studied in 61 epileptic children. Enzyme-immunoassay (EMIT)R methods gave higher values of total VPA concentration than gas-liquid chromatography (GLC) methods. In over 80% of children with complete seizure control the ranges of total VPA concentration were 140-420 mumol/L with GLC methods and 210-560 mumol/L with EMIT methods. The range of free VPA concentrations in 78% of children with complete seizure control was 8.8-26.4 mumol/L. Increased liver enzyme activity was observed in 6 of the 61 children and raised plasma ammonia concentration in 11 of 50 children. Plasma ammonia concentration was related to total serum VPA but was not related to free serum VPA. Increased serum liver enzyme activity was related to VPA dose per kg but not to free or total serum VPA concentration. Thus free VPA concentrations do not appear to be more useful than total VPA concentrations in predicting seizure control and do not correlate with liver enzyme activity or plasma ammonia concentration.

Adolescent↗
PubMed1986

The effect of aspirin on valproic acid metabolism.

Urinary valproic acid (VPA) and VPA metabolite profiles were determined before (day 1) and after (day 2) the administration of antipyretic doses of acetylsalicylic acid (ASA) to seven subjects with steady-state levels of VPA. Of the 13 metabolites assayed by GC/MS, levels of (E)-2-ene VPA and 3-keto VPA were significantly decreased on day 2, whereas those of the VPA conjugates (glucuronide) and 4-ene VPA were significantly increased. The beta-oxidation pathway consisting of (E)-2-ene VPA, 3-OH VPA, and 3-keto VPA was decreased from 24.5% +/- 10.3% of total metabolites excreted on day 1 to 8.3% +/- 4.2% on day 2, a decrease of 66% (P less than 0.05). VPA glucuronide content increased from 50.5% +/- 12.6% on day 1 to 65.5% +/- 14% of total excreted on day 2, an increase of 30% (P less than 0.05). The day 2/day 1 ratios of VPA glucuronide correlated significantly with the day 2/day 1 ratios of VPA mean free fraction (r = 0.9424; P = 0.005) in six of the seven subjects. Inhibition of VPA beta-oxidation by salicylate was sufficient to counterbalance the increased elimination of VPA as its conjugates and explains why total clearance of VPA after salicylate remains unchanged even though the free fraction of VPA is increased. Metabolic profiles indicate that salicylate likely inhibits VPA beta-oxidation by reducing valproyl-coenzyme A formation.

Adolescent↗
PubMed1986

Eye and head movements of visually impaired children.

Fixation, nystagmus, pursuit, rapid voluntary, other types of eye movements and associated head movements of visually impaired children were studied. It was concluded that their eye and head movements reflect the severity and onset of their visual loss.

Child↗
PubMed1986

Benzodiazepines in the treatment of children with epilepsy.

Atonic seizures, atypical absence seizures, myoclonic seizures, tonic seizures, and infantile spasms are among the most difficult to control in children. Certain 1,4-benzodiazepines may be effective against these seizure types. Thus, clonazepam has been shown to reduce the frequency of absence, atypical absence, myoclonic, atonic, and complex partial seizures in children. Furthermore, both clonazepam and nitrazepam have been shown to be effective in the treatment of infantile spasms. However, their usefulness is limited by a deleterious effect on neurologic function, particularly on cognition. Controlled studies in animals and in adult patients and volunteers have demonstrated that clobazam has less neurotoxicity than 1,4-benzodiazepines and, in addition, may possess a psychotropic effect. Uncontrolled studies of clobazam in children suggest that this drug may be effective in the treatment of partial seizures, startle-induced seizures, infantile spasms, and Lennox-Gastaut syndrome. We studied the effect of clobazam in children whose seizures were resistant to most other antiepileptic drugs. Mental retardation was present in 80% of the children, and 62.5% had Lennox-Gastaut syndrome. Tolerance to clobazam developed in approximately one-third of patients, but this was frequently only partial and often responded to an increase in dosage. Of 50 children studied for a minimum of 3 months, seizures were controlled completely in 10 and frequency of seizures was reduced by more than 50% in a further 17. In most cases, parents observed a striking improvement in neurologic function, particularly in alertness, concentration, and balance. Thus, clobazam may be of value in the treatment of those seizures which are most difficult to control in children.

Anti-Anxiety Agents↗
PubMed1985

Pseudoarylsulfatase-A deficiency in the neurologically impaired patient.

The demonstration of low arylsulfatase-A (ASA) activity in leucocytes or fibroblasts is used often to establish the diagnosis of metachromatic leucodystrophy (MLD). However, low ASA activity is observed also in pseudo-ASA deficiency which may be as common as MLD. We report two patients with pseudo ASA deficiency who had abnormal neurological findings consistent with atypical MLD. Because the measurement of ASA activity is neither a sensitive nor specific method with which to establish a diagnosis of MLD, this diagnosis should be confirmed by nerve biopsy, measurement of urinary sulfatide or a cerebroside sulfate loading test, using cultured fibroblasts.

Adult↗
PubMed1985

Permanent cortical visual impairment in children.

Fifty patients with permanent cortical visual impairment were evaluated. They had a characteristic behaviour profile, usually with residual sight but poor visual attention. 30 of the 50 also had damage to the anterior visual pathway. Visual evoked potential mapping was shown to have a clear advantage over visual evoked responses, and using that in conjunction with CT and clinical data enabled several subgroups of cortical visual impairment to be identified. The diagnosis probably is more common than previously recognised, and should be suspected when there is greater delay in visual development in other areas and the degree of visual loss is unexplained by ocular findings. Using traditional criteria for cortical blindness may mean that many children are not diagnosed, which has serious implications for their rehabilitation.

Adolescent↗
PubMed1985

Permanent visual loss after shunt malfunction.

Fourteen (1.8%) of more than 800 children evaluated in a Visually Impaired Program over 10 years became permanently blind during an episode of raised intracranial pressure secondary to shunt malfunction. Visual symptoms and papilledema were recognized in only three children at the onset of blindness. Clinical and radiologic findings suggested that the loss of sight was caused by a lesion in the pregeniculate pathway in nine patients, probably due to ischemia; five children in the postgeniculate group sustained infarcts of the occipital lobes. These cases highlight the importance of parent education and prompt treatment of raised intracranial pressure due to shunt malfunction.

Blindness↗
PubMed1984

Computed tomography in Alexander's disease.

Computed tomography demonstrated contrast-enhancing lesions in the periventricular frontal regions, caudate nuclei, and thalami in an infant with Alexander's disease. The distribution of the enhancing lesions corresponded to the areas in which Rosenthal fibers were most prominent. These radiological findings have not been described in other white matter diseases; thus, they may help to distinguish Alexander's disease from Canavan's disease and decrease the necessity for diagnostic brain biopsy.

Brain↗
PubMed1984

Lesions of the putamen and dystonia: CT and magnetic resonance imaging.

We studied posthemiplegic hemidystonia in an adult, and generalized dystonia in two children. CT and magnetic resonance imaging (MRI) studies in the adult revealed infarction of the contralateral putamen and, to a much lesser extent, the head of the caudate nucleus. Both children had subacute encephalopathies (possible Leigh's disease), and CT revealed bilateral putamen lesions when generalized dystonia was the predominant clinical disorder. These cases and other reports of symptomatic dystonia suggest that lesions of the putamen correlate with dystonia.

Brain Diseases↗
PubMed1983

Analysis of the interrelationships of non-nutrient blood flow, oxygen delivery, oxygen consumption, and the ratio of oxygen delivery/oxygen consumption based on a mathematical model of non-nutrient blood flow.

A mathematical model for total body non-nutrient blood flow has been presented. This is a gross model that will show effective non-nutrient blood flow. It shows how NNBF can occur in the setting of decreased oxygen delivery. The implications of this model on the interrelationships of oxygen delivery, oxygen consumption, the ratio of oxygen delivery/oxygen consumption, and NNBF are discussed.

Acidosis↗
PubMed1983

The effects of peritoneal dialysis on the single dose and steady state pharmacokinetics of valproic acid in a uremic epileptic child.

The pharmacokinetics of valproic acid (VPA) have been studied during peritoneal dialysis in a uremic male epileptic child following a single 500 mg dose and after multiple doses over 5 months (700 mg daily) of valproic acid as the syrup. Serum level decline was biphasic in both instances with a terminal half-life of 27.2 after the single dose and 10.2 h at steady-state. Total serum clearance was 0.0236 l/h/kg after the single dose and increased to 0.0408 l/h/kg after 5 months. Free (intrinsic) serum clearances were 0.1489 and 0.1518 l/h/kg and serum free fractions were 0.224 and 0.272 respectively for the single dose and steady-state studies. Peritoneal dialysis for periods of 12 or 24 h removed an average of 4.5% of the VPA dose.

Child↗
PubMed1983

Serum and plasma for total and free anticonvulsant drug analyses: effects on EMIT assays and ultrafiltration devices.

The suitability of serum and plasma anticoagulated with heparin, EDTA, citrate, or oxalate was assessed for analysis of free and total phenytoin, carbamazepine, and valproic acid. The free fraction was isolated by ultrafiltration through FreeLevel devices (Syva, Palo Alto, CA). Serum, heparin, and EDTA plasma were satisfactory for both free and total phenytoin and carbamazepine. EDTA could not be used for EMIT (Syva) analysis of valproate. Citrate and, to a lesser degree, oxalate cause a significant negative interference in the concentration of these three drugs as measured both by EMIT and gas-liquid chromatography.

Anticonvulsants↗
PubMed1983

Arthrogryposis following maternal hypotension.

A case of arthrogryposis multiplex congenita is described, in which the pregnancy had been complicated by a prolonged hypotensive period on the 86th day of gestation. The similarity in pathological findings between ischaemic myelopathy and arthrogryposis suggest that maternal hypotension was an aetiological factor in this infant's arthrogryposis.

Arthrogryposis↗