Biomedical subjects
Publications and source records attributed to R Hall.
The possibility of mumps was considered in 33 children with profound unilateral sensorineural hearing loss of unknown origin. Fifteen gave a history of mumps, of whom 12 contracted the infection between the last normal and first abnormal hearing tests. Hearing should be tested after mumps infection.
Two experiments are described that investigate the detectability of signals embedded in spatially uncorrelated visual noise. The signals were thin lines extending vertically from the top to the bottom of the noise background and were essentially of two classes. One class consisted of signals whose pixel luminances were spatially uncorrelated, the other of signals whose pixel luminances were sinusoidally modulated along their length. In both classes the space-average luminance of the signals was greater than that of the noise. In the first experiment it was found that the modulated signals were more visible than the unmodulated, even though the space-average luminance of both types was equal. For the modulated signals visibility was proportional to the amplitude of modulation and inversely proportional to the spatial frequency of modulation. Neither an ideal-observer model nor an energy-integrator model was found to give a good account of the results. On the other hand, a model referred to as the maximum filter output model gave an excellent account of the data. The model employed a simple energy-integrating filter approximately 0.8 deg in length and recorded the filter's maximum output for every potential signal, indicating the signal as the line that gave the largest output. In a second experiment, modulated signals that contained added random luminance perturbation were used, and again the model was found to give a good fit to the data. The findings are discussed in the context of known properties of cortical-bar detectors.
A study was conducted to investigate the effect of Lugol's iodine on the superior thyroid artery (STA) blood flow with use of a Duplex ultrasound scanner for 12 patients with Graves' disease. All patients were treated with antithyroid drugs until they were euthyroid and then, with randomization, the patients received either Lugol's iodine, 0.3 ml thrice daily, or placebo for 9 days in a double-blind fashion. Antithyroid drugs were continued throughout the study. Reduction in the diameter, time-averaged velocity (TAV), and volume flow (VF) of the STAs was demonstrated in all patients in the treatment group, whereas there were no consistent trends in the placebo group. The changes in TAV and VF were significantly different between the placebo and treatment groups (p less than 0.01 for TAV and p less than 0.005 for VF). These changes were more marked in patients with high initial VF and minimal in patients with low initial VF. On the basis of these results, we recommend that patients with high thyroid blood flow before thyroidectomy should receive Lugol's iodine preoperatively.
Using a two-site immunoradiometric assay, we measured concentrations of thyrotropin (TSH) in serum of 134 clinically euthyroid subjects, 93 patients with nonthyroidal illness, and 80 patients who were being treated with various drugs. Abnormal concentrations of TSH, free thyroxin, and free triiodothyronine, respectively, were recorded in serum of three (3.2%), 19 (20.4%), and 37 (39.8%) of the patients with nonthyroidal illness and in three (3.8%), five (6.3%), and 10 (12.5%) of the patients taking drugs. TSH could be detected in all patients' serum samples. We conclude that, for most patients without thyroid disease, a basal (i.e., unstimulated) measurement of their TSH concentration in serum will indicate their thyroid status more reliably than will assay of free thyroxin or free triiodothyronine.
Explore the source record for details and available documents.
Clinical guidelines and a weekly review of medical records were introduced into a medical unit in a teaching hospital to promote a more discriminating use of laboratory tests. This strategy resulted in an immediate reduction in the average number of requests each week from 74 to 27 haematological tests (64%) and 158 to 58 biochemical tests (64%). During a period of 10 weeks after the strategy was introduced (the intervention period) the mean number of haematological tests for each person decreased from 2.0 during the baseline period to 1.1 (45% reduction; p less than 0.01) and the mean number of biochemical tests decreased from 4.4 to 2.7 (39%; p less than 0.0001). The decrease in the number of repeat requests was greater than that for new requests and accounted for half the reduction in use. There was no significant change in the number of tests requested from an adjacent medical unit that was not exposed to the interventions. This strategy is worthy of trial in other specialties and hospitals, but attention will have to be paid to possible difficulties in sustaining reductions in use over long periods of time.
Of 162 female patients with imperforate anus, 21% had a noncommunicating and 79% a communicating anomaly of the rectum or anus. Associated anatomical abnormalities were found in the lower urinary tract (15%), upper urinary tract (25%), lower genital tract (27%), upper genital tract (35%), and additional organ systems (51%). Death occurred in 26 patients and in 19, this was attributed to the associated abnormalities. Functional outcome was assessed in those patients 13 years of age or older. Bowel function was normal or near normal in 85%, as was urinary and renal function. In 44% of patients evaluated, there was persistent vaginal abnormality or scarring and in 25%, this was severe enough to require future surgery.
Explore the source record for details and available documents.
It is well known that muscarinic cholinergic blockade either reduces or abolishes stimulated GH release in normal subjects. In this study we have investigated whether cholinergic muscarinic blockade could reduce the GH responses to GRF 1-29 and TRH in acromegalic subjects. Eight acromegalic subjects underwent two GRF tests (GRF 1-29, 1 microgram/kg i.v.) with and without pirenzepine (0.6 mg/kg, i.v.). A further four of these patients received TRH (200 micrograms/kg, i.v.) on separate occasions with and without pirenzepine (0.6 mg/kg, i.v.). Cholinergic muscarinic blockade did not alter the GH responses to GRF and TRH in patients with acromegaly. These findings are in contrast with previous data reported on the effects of cholinergic blockade on stimulated GH levels in normal subjects and in patients with type I diabetes mellitus and are compatible with the view that somatotroph adenomas are functionally disconnected from hypothalamic control mechanisms.
We report here our results of the pre- and post-operative assessment of prolactin and TSH status in 41 hyperprolactinaemic patients who underwent pituitary surgery over a 5 year period. Preoperatively in patients with prolactinomas (n = 33) the TSH response to domperidone decreased with increasing adenoma size. When the data are expressed on a group mean basis the exaggerated TSH response to domperidone in preoperative prolactinoma patients was reduced significantly in patients rendered normoprolactinaemic by surgery but persisted in those who remained hyperprolactinaemic. Similarly the reduced preoperative PRL responses to domperidone and TRH were significantly increased by successful surgery. In contrast patients with stalk-compression hyperprolactinaemia (n = 6) due to larger lesions which were not prolactinomas all showed reduced or absent TSH responses to domperidone. The PRL responses to domperidone and TRH were reduced or absent both in patients with prolactinomas and in those with stalk-compression hyperprolactinaemia. All patients with stalk-compression hyperprolactinaemia showed a delayed pattern of TSH response to TRH with 60 min values being greater than 20 min ones. In contrast a normal pattern of TSH response to TRH was observed in all patients with hyperprolactinaemia due to prolactinomas. Postoperatively TSH and PRL responses were largely unchanged in patients with stalk-compression hyperprolactinaemia regardless of whether normoprolactinaemia was restored by surgery. In conclusion a reduced or absent PRL response to TRH or domperidone is not diagnostic of the presence of a prolactinoma since it occurs in hyperprolactinaemic patients with prolactinomas or stalk-compression. In contrast, the TSH response to acute dopamine antagonism is exaggerated in most patients with small prolactinomas but not in those with stalk-compression hyperprolactinaemia and we have found this to be helpful diagnostically since the presence of an exaggerated TSH response to dopamine antagonism is evidence against the presence of stalk-compression hyperprolactinaemia. The observation of a delayed TSH response to TRH in a hyperprolactinaemic patient should alert the clinician to the possibility of stalk-compression hyperprolactinaemia due to a large lesion which may not be a prolactinoma.
To assess the effect of cholinergic blockade on the ACTH, beta-endorphin and cortisol responses to insulin-induced hypoglycaemia, six healthy male volunteers each underwent two insulin tolerance tests in random order, separated by at least 1 week with and without atropine. ACTH levels were significantly greater at +45 min (mean +/- SEM, 223 +/- 21 pg/ml vs 148 +/- 15 pg/ml, P less than 0.01) and at +120 min (54 +/- 11 pg/ml vs 29 +/- 10 pg/ml, P less than 0.05). beta-endorphin levels were significantly greater at +30 min (170 +/- 45 pg/ml vs 96 +/- 32 pg/ml, P less than 0.05) and at +105 min (81 +/- 14 pg/ml vs 54 +/- 7 pg/ml, P less than 0.01). Cholinergic blockade had no effect on plasma glucose or cortisol concentrations. This study demonstrates that cholinergic blockade with atropine facilitates the ACTH and beta-endorphin responses to insulin-induced hypoglycaemia without altering the cortisol responses.
It is well known that hypothyroidism is frequently associated with impaired GH responses to different stimuli. In the present study we have evaluated GH responses to GH-releasing factor (GRF) in patients with primary hypothyroidism before and during T4 replacement therapy. Fourteen patients (age range 26-60 years) underwent two GRF tests (1 microgram/kg) before and during replacement therapy (150 micrograms/d). Administration of T4 increased peak GH responses to GRF in 9 patients and in the group as a whole (mean +/- SEM, 17.0 +/- 2.8 vs 32.6 +/- 5.7 mU/l, P less than 0.02). When the data are analysed by means of area under the curve (AUC), the GH response to GRF was increased by T4 in 10 patients and in the group as a whole (mean +/- SEM, 51.7 +/- 14.3 vs 101.5 +/- 28.1, P less than 0.02). These data indicate that thyroid hormone replacement therapy enhances the responsiveness of the somatotroph to GRF 1-29 in patients with primary hypothyroidism.
Cholinergic pathways play an important role in the regulation of GH secretion from the anterior pituitary gland, and in this study we have investigated whether cholinergic muscarinic receptor blockade with pirenzepine displayed any inhibitory action on slow wave sleep-related GH release in normal subjects. Six adult males (ages 24-37 years) were studied in a randomized order and fasted from 1800 h on each study day. All subjects showed episodes of slow wave sleep on each occasion and this was followed by peaks of GH release when placebo alone was administered (range of GH peaks 4-50 mU/l). In contrast, pirenzepine treatment (100 mg p.o. at 2200 and 2400 h) completely abolished nocturnal GH release in each individual without altering the occurrence of slow wave sleep itself. These data demonstrate clearly that cholinergic muscarinic receptor blockade completely abolishes slow wave sleep-related GH release in normal adult subjects. Because of the striking effects it is reasonable to conclude that acetylcholine plays an important stimulatory role in mediating slow wave sleep-related GH release. This finding may have investigational and therapeutic applications in young patients with Type 1 diabetes mellitus since GH is implicated in some acute metabolic and chronic microvascular complications of this disease.
It has been reported recently that patients with hyperprolactinaemia may develop hypothyroidism as a consequence of the increased inhibition of TSH release by dopamine which occurs in the majority of such patients. In this study we have evaluated thyroid function in a large number of hyperprolactinaemic patients in order to delineate more precisely the relationship between thyroid status, free thyroid hormone levels and the control of TSH release by dopamine. Biochemical euthyroidism was present in the majority of the hyperprolactinaemic patients. Our data indicate that the increased dopaminergic inhibition of TSH release does not lead to hypothyroidism. Instead, the slightly elevated basal TSH levels and TSH responses to TRH (within the normal range) may reflect the operation of a compensatory mechanism to maintain euthyroidism in the face of te increased inhibition of TSH release by hypothalamic dopamine.
In order to establish the influence of dopaminergic, alpha-adrenergic and cholinergic pathways on GRF-mediated GH release we have studied the GH responses to GRF 1-29 (100 or 50 micrograms as i.v. bolus) alone and in combination with metoclopramide (MCP, 10 mg, i.v.), thymoxamine (THYM, 210 micrograms/min, 150 min infusion), and atropine (1.2 mg, i.v.). We have also investigated any possible interaction between TRH and GRF in view of the reported inhibitory effects of TRH infusion on stimulated GH release. Dopaminergic and alpha-adrenergic blockade with MCP and THYM respectively, did not have any effect on the GH responses to GRF. This lack of effect strongly suggests that any action which these neurotransmitters may exert on GH secretion is not at a pituitary level. TRH did not modify the GH response to GRF suggesting that the inhibitory effect on stimulated GH secretion is exerted at a hypothalamic level. In contrast, GH responses to GRF were significantly reduced by prior administration of atropine. These data support the view that cholinergic pathways play an important role in the regulation of GH secretion and such control may be exerted at both hypothalamic and pituitary levels.
The efficacy of audiotape was compared with that of videotape as a way of teaching students the essentials of the medical interview. Two consultants--a general physician and a neurologist--were videotaped as they took histories from two patients. The neurologist described his methods and summarized his findings, but his interview was conducted conventionally without interruptions (continuous interview). In a contrasting style, the general physician frequently explained his methods and findings in steps, interrupting his interview to do this (discontinuous interview). Fifty students starting their main medical term were divided into two groups (A and B). Group A was shown the videotape of the discontinuous interview while group B was played an audiotape of that interview. Groups A and B were then crossed over, but this time group A was allowed only to hear the audiotape of the continuous interview, while the videotape of it was played to group B. After each tape the students were tested on its content. There was no significant difference between the mean scores of Group A and Group B when tested on the discontinuous interview and both groups scored well. For the continuous interview the group who saw the videotape scored significantly better than the group who only heard this tape. Both groups scored significantly better in the test based on the discontinuous interview than they did in the test based on the continuous interview. The results indicate that videotapes are a good medium for teaching history-taking, but also suggest that audiotape recordings of medical history-taking can be effective teaching aids if the interview is explained in stages.
Chondrosarcoma of the larynx is a rare disease. The condition usually presents as a space-occupying lesion in the larynx. It is usually internal, but an external mass may be noted. Diagnosis demands a deep biopsy as the tumour is submucosal. Treatment is surgical, but the extent of this surgery is dependent upon the stage of the disease. The prognosis, in most cases, is usually very good. The literature relating to chondrosarcoma of the larynx is reviewed and salient features are presented. Added interest in this case is due to the long precedent history and the difficulty in obtaining a diagnosis.