Adrenal cortical mitochondria contain a mixed function oxidase capable of converting cholesterol to pregnenolone; this enzyme requires NADPH, oxygen and cholesterol. This cholesterol side chain cleavage enzyme system contains a Flavoprotein, an iron sulphur protein and a specific cytochrome P450 termed cytochrome P450scc. ACTH stimulates the adrenal cortex by activating adenyl cyclase producing an elevated intracellular concentration of cAMP. This in turn increases the activity of a cytosolic cAMP dependent protein kinase. Adrenal cortical cytosol contains a cholesterol ester hydrolase which is activated by ATP and a protein kinase. This enzyme may be deactivated by a phosphoprotein phosphatase. The adrenal cortex contains lipid droplets that are rich in esterified cholesterol. Cholesterol ester hydrolase can release free cholesterol from the lipid droplets. The free cholesterol released may be used to supplement the mitochondrial cholesterol as a pregnenolone precursor. Steroid hormone production by the adrenal cortex exhibits a diurnal rhythm and correlates with the activity of the cytosolic cholesterol ester hydrolase. The acute steroidogenic response to ACTH may be in part attributed to the availability of free cholesterol to the mitochondrial cholesterol side chain cleavage enzyme complex. The intracellular movement of free cholesterol from lipid droplets to mitochondrial inner membranes may be impeded by protein synthesis inhibitors such as cycloheximide. The precise mechanism of this block in steroidogenesis remains to be elucidated. Various drugs and oestrogenic hormones suppress the plasma and adrenal cholesterol concentrations. If adrenal cells are deficient in cholesterol, these cells exhibit a diminished response to ACTH. The response to this hormone can be corrected by supplying cholesterol via exogenous plasma lipoproteins. The route that free cholesterol follows within the adrenal cortical cell and the physiological factors influencing free cholesterol movement in such cells are important issues to be explored in future.

Adrenal Cortex↗

PubMed1977

Use of constraint-seeking questions by retarded and nonretarded individuals.

A 20-questions problem-solving task was given to 116 EMR adolescents and 65 nonretarded MA-equated fourth graders. The subjects' questions were classified as either constraint seeking or nonconstraint seeking, and the problem-solving strategies were evaluated in terms of their efficiency of solution. Results indicated that the nonretarded group asked more constraint-seeking questions, and their strategies reflected more efficient problem-solving solutions. The majority of subjects in both groups appeared to be in Mosher and Hornsby's (1966) suggested transitional stage, as demonstrated by the fact that their strategies fell between employing only questions that eliminated one item in the stimulus array (hypothesis scanning) and questions that consistently eliminated the maximum number of items (perfect focusing). In addition, nonretarded subjects' strategies reflected a greater awareness of the apparent organizational demands of the task and especially an awareness of the entire range of dimensions in the stimulus array.

Adolescent↗

PubMed1975

Chondrosarcoma of the maxillary antrum presenting as exophthalmos.

A Papau New Guinean patient with a chondrosarcoma of the maxillary antrum producing exophthalmos is presented. The importance of considering causes other than thyrotoxicosis in the aetiology of exophthalmos is stressed and a summary of the clinical features, pathology and management of the tumour is given.

Child↗

PubMedDate not supplied

Clinical neurophysiology referral patterns to a tertiary hospital--a prospective audit.

BACKGROUND: Cork University Hospital (CUH) provides a tertiary service for all neurophysiology referrals in the Southern Health Board region. AIM: To ascertain the number, source, symptoms and diagnosis of neurophysiology referrals at CUH. METHODS: We did a prospective audit of the referral patterns to the neurophysiology department over a 12 -week period. RESULTS: Of 635 referrals, 254 had electromyograms (EMG), 359 had electro-encephalograms (EEG), 18 had visual evoked potentials (VEP), three had somato-sensory evoked potentials (SSEP) and one had multiple sleep latency tests (MSLT). We analysed the demographic pattern, reason for referrals, the average waiting time for neurophysiology tests and the patterns of diagnosis in this audit. CONCLUSIONS: Patients from County Cork are making more use of the neurophysiology services than patients from other counties within the Southern Health Board. The average waiting time for an EEG was 32 days and for an EMG was 74 days. However, more than 35% of those patients waiting for an EEG or an EMG had their tests done within four weeks of referral. The appointments of EEG and EMG were assigned on the basis of clinical need.

Adolescent↗

PubMedDate not supplied

How well is peripheral neuropathy investigated? An audit from a regional neurophysiology department.

BACKGROUND: Peripheral neuropathy (PN) is common and increases with age. AIM: To assess how patients with confirmed peripheral neuropathy on nerve conduction studies (NCS) were investigated and to determine whether there was any difference in investigation based on patient age or referral source. DESIGN: Retrospective audit. METHODS: All EMG/NCS reports from a one-year period were analysed. The computer laboratory system was used to determine which blood tests had been performed on those patients with confirmed peripheral neuropathy on NCS. RESULTS: Over 50% of patients referred from within the hospital did not have a basic blood screen to search for the aetiology. There was no significant difference in investigation practise based on patient age or referral source. CONCLUSION: Our results highlight the lack of systematic investigation in a university teaching hospital. As a result of this audit, a protocol has been prepared and is distributed with NCS/EMG reports.

Age Factors↗

PubMedDate not supplied

Treatment controversies in Bell's palsy.

Explore the source record for details and available documents.

Bell Palsy↗

PubMedDate not supplied

Video-EEG recording: a four-year clinical audit.

In the setting of a regional neurological unit without an epilepsy surgery service as in our case, video-EEG telemetry is undertaken for three main reasons; to investigate whether frequent paroxysmal events represent seizures when there is clinical doubt, to attempt anatomical localization of partial seizures when standard EEG is unhelpful, and to attempt to confirm that seizures are non-epileptic when this is suspected. A clinical audit of all telemetry performed over a four-year period was carried out, in order to determine the clinical utility of this aspect of the service and to determine means of improving effectiveness in the unit. Analysis of the data showed a high rate of negative studies with no attacks recorded. Of the positive studies approximately 50% showed non-epileptic attacks. Strategies for improving the rate of positive investigations are discussed.

Electroencephalography↗