Tips for successful all-ceramic restorations.
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Dental Casting Technique↗
Biomedical subjects
R D Jones
Publications and source records attributed to R D Jones.
Effect of metoclopramide on luteinizing hormone secretion in postpartum anestrous cows.
The effect of metoclopramide (MC), a dopamine antagonist on luteinizing hormone (LH), was examined in anestrous primaparous cows. Metoclopramide has been found to be beneficial in overcoming fescue toxicosis; increasing LH secretion stimulates return to ovulatory function after parturition. Consequently, if MC had negative effect on LH secretion, it would indicate that administration of MC to reproducing animals might be limited. Of 14 postpartum (47 to 66 days) cows, 7 were given MC (4 mg/kg of body weight, IV), and 7 served as controls. Blood was obtained via jugular cannulas at 15-minute intervals for 8 hours; MC was given at the end of the first hour, and gonadotropin-releasing hormone (GnRH, 7 mg/kg), was given IV at the end of hour 7 as a challenge stimulus for LH secretion. Prior to GnRH administration, MC did not have significant effect on LH secretion, as judged by mean serum LH concentration, LH pulse frequency, and LH pulse amplitude. Administration of MC resulted in greater (P less than 0.05) LH response to GnRH, indicating enhanced secretory ability when the pituitary gland was challenged. Serum prolactin concentration was increased (P less than 0.01) by MC administration. Therefore, MC did not have adverse effect on LH secretion in postpartum cows.
Anestrus↗
The effect of scheduling in children undergoing prophylactic cranial irradiation for acute lymphoblastic leukaemia.
Control of central nervous system (CNS) disease and overall survival have been analysed in a group of 829 children with leukaemia entered into the UKALL VIII trial to determine whether scheduling of the cranial irradiation is of prognostic significance. We show that short gaps in treatment do not influence prognosis and that current radiotherapy practice need not be modified.
Age Factors↗
Wisconsin Card Sorting Test performance as a measure of frontal lobe damage.
We examined the sensitivity and specificity of the Wisconsin Card Sorting Test (WCST) as a measure of frontal lobe damage in 91 subjects with stable focal brain lesions. Anatomical information about the location and extent of brain damage was obtained from MR and CT transparencies. No significant differences in WCST performance were found between subjects with frontal vs. nonfrontal damage. Some subjects with extensive frontal lobe damage performed well on the WCST, and some subjects with damage outside of the frontal lobes failed. The optimal cutoff scores for discriminating frontal from nonfrontal subjects correctly classified only 62% of the subjects. Further analysis of WCST performances associated with damage to various subregions of the frontal lobes also failed to reveal any reliable relationships. These findings indicate that performance on the WCST cannot be interpreted in isolation as an index of frontal lobe damage.
Aging↗
Antagonism of the hypnotic effect of midazolam in children: a randomized, double-blind study of placebo and flumazenil administered after midazolam-induced anaesthesia.
In a randomized, double-blind study, we administered placebo and flumazenil to 40 healthy Chinese boys, aged 3-12 yr, undergoing circumcision. The children received midazolam 0.5 mg kg-1 orally for premedication and 0.5 mg kg-1 i.v. during induction. After operation the patients were given 0.1 ml kg-1 of a blinded solution followed by 0.05 ml kg-1 min-1 until either they awoke or the 10-ml ampoule of solution was empty. Efficacy of antagonism of midazolam was assessed by times to eye opening and self identification, modified Steward coma scale, a post-box toy completion-time ratio and qualitatively by an independent observer. The difference between flumazenil and placebo was both clinically and statistically different in the first 2 h. Children receiving flumazenil awoke approximately four times faster and identified themselves nearly three times sooner; 65% of this group could complete the post-box toy at 10 min, compared with none of the placebo group. There were no cases of resedation, but one child did not awaken for 30 min after i.v. administration of flumazenil 1.0 mg. The mean total dose of flumazenil administered was 0.024 (SD 0.019) mg kg-1. Flumazenil rapidly antagonized midazolam-induced hypnosis in children and was associated with minimal change in cardiorespiratory variables.
Anesthesia Recovery Period↗
Byssinosis in the cotton waste industry.
A cross-sectional survey was carried out on 772 workers in 27 mills in the North of England involved in the processing of cotton waste. The overall prevalence of byssinosis as defined by Schilling's criteria was 9.8 per cent with 5.4 per cent having grades 2 and 3. The prevalence in workers who had only ever had cotton waste exposure (5 per cent) was significantly less than for those who had mixed waste and raw cotton exposure. There was no clear relationship between prevalence of byssinosis and years of exposure or dust levels.
Adolescent↗
A comparison of two-lung high frequency positive pressure ventilation and one-lung ventilation plus 5 cm H2O non-ventilated lung CPAP, in patients undergoing anaesthesia for oesophagectomy.
A randomised prospective controlled study was conducted during a one-year period on patients scheduled for oesophagectomy via a right thoracotomy approach. Twenty-two patients received one-lung ventilation (OLV group) and twenty patients received high frequency positive pressure ventilation (HFPPV group). Episodic hypoxaemia (SaO2 less than 90% for greater than 30 seconds, FiO2 1.0) occurred in eleven patients in the OLV group and six patients in the HFPPV group. No patient in the HFPPV group had a severe desaturation episode (SaO2 less than 80%, FiO2 1.0) compared with nine patients in the OLV group (P less than 0.05). The mean peak inspiratory pressure and average mean airway pressure were significantly lower in the HFPPV group 28.8 (SD 7.7) and 7.2 (SD 2.4) cm H2O respectively, compared with the OLV group, 40.0 (SD 9.9) and 11.9 (SD 4.9) cm H2O (P less than 0.05). Two-lung high frequency positive pressure ventilation has some advantages over one-lung ventilation during the thoracotomy phase of oesophagectomy because it is easy to administer, does not significantly compromise the surgical exposure and is associated with fewer severe undesirable physiological disturbances.
Aged↗
Postoperative analgesia for oesophageal surgery: a comparison of three analgesic regimens.
Sixty-four patients undergoing oesophageal surgery were randomly allocated to receive either a continuous lumbar epidural infusion of morphine or fentanyl, or, intramuscular morphine for postoperative analgesia. There was no statistical difference in analgesic requirements between the patients who underwent a thoracotomy for their procedure (n = 50) and those who did not (n = 14), as assessed by the total dose of opioid administered, visual analogue scale (VAS) and pain score (PS) comparison. However, by these criteria, epidural morphine infusion provided the most satisfactory analgesia (P less than 0.05). Despite the variable quality of analgesia achieved with the three regimens, the postoperative lung function tests were similar for all groups, and we conclude that routine lung function tests are not an appropriate method of comparing analgesic efficacy. Prophylactic administration of loratadine to 15% of our patients was not shown to be effective in diminishing the incidence of pruritus.
Adult↗
An iridium-192 applicator for the treatment of stomal recurrence following tracheostomy for subglottic carcinoma.
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Brachytherapy↗
Determination of metoclopramide in the serum and urine of cattle.
Metoclopramide, a dopamine-2 agent, has been shown to be useful in the antagonism of fescue toxicosis in grazing steers. The determination of this drug is described for the purpose of pharmacokinetic study and consideration of potential delivery devices to combat this economically significant condition.
Acetates↗
Fenvalerate/N,N-diethyl-m-toluamide (Deet) toxicosis in two cats.
Toxicosis attributable to fenvalerate and N,N-diethyl-m-toluamide (Deet) exposure was suspected in 2 cats. Clinical signs of toxicosis developed within 4 to 6 hours of dermal application of the pesticide. Clinical signs of toxicosis seen in both cats included hypersalivation, ataxia, and depression. In addition, seizures were seen in 1 cat. Both cats died. Analysis of skin, kidney/urine, liver, and brain tissues confirmed the presence of fenvalerate and Deet. The pyrethroid fenvalerate and the insect repellent Deet are used for the control of fleas and ticks on cats. Suspected fenvalerate/Deet toxicosis in cats is associated with tremors, hypersalivation, ataxia, vomiting, depression, and seizures.
Animals↗
A comparison of remote afterloading and manually inserted caesium in the treatment of carcinoma of cervix.
Between 1982 and 1985, 240 patients with carcinoma of cervix were treated by radical radiotherapy, 140 using the selectron at the Royal Beatson Memorial Hospital (RBMH) and 100 with conventional caesium at the Western Infirmary. To allow for the increased dose rate to point A (1.2-1.4 Gy/h) during selectron treatment the overall intracavity dose was reduced by a mean value of 25%. Local recurrence rates were similar: 15% (selectron) against 14% (conventional). Three-year survival with local control was somewhat worse in the selectron group (77% against 81%) mainly because of an increased frequency of metastatic disease with local control (19.3% against 12.0%. The use of remote afterloading has not increased late morbidity (15.7% selectron, 15.0% conventional). The introduction of the selectron has brought about a marked reduction in staff radiation exposure. At the RBMH the mean recorded dose to nurses fell from 19 mSv in 1981 to 2.4 mSv in 1985.
Brachytherapy↗
A pilot study of quinidine and epirubicin in the treatment of advanced breast cancer.
Thirty-one patients were entered into a pilot study combining oral quinidine with epirubicin 100 mg m-2 as first line chemotherapy in advanced breast cancer. Three patients were treated with quinidine 1 g b.d., and developed symptoms of toxicity. Of eight subsequent patients treated with quinidine 500 mg b.d., two experienced tiredness and nausea and one severe oral toxicity with epirubicin. The remaining 20 patients received quinidine 250 mg b.d.; one developed cinchonism and one malaise, the remainder showing no excess toxicity compared with epirubicin alone. The median nadir WBC was similar with or without quinidine (2.3 vs 1.6 x 10(9) l-1) as was median nadir platelet count (175 vs 157 x 10(9) l-1). There was no evidence of significant cardiac toxicity. The median plasma quinidine level achieved was 5.6 mumol l-1 (range 2.1-22.1), which is within the range of concentrations which is effective in vitro at reversing experimental anthracycline resistance. A randomised controlled study is proposed to assess the impact of this potential modulation on the efficacy of epirubicin in advanced breast cancer.
Adult↗
Pharmacokinetics of propofol in children.
The pharmacokinetics of propofol were studied in 12 healthy Chinese children, aged 4-12 yr, undergoing circumcision under inhalation anaesthesia. All patients received a single i.v. bolus dose of propofol 2.5 mg kg-1 and blood concentrations of propofol over the subsequent 24 h were measured using high pressure liquid chromatography with fluorimetric detection. Data were consistent with a three-compartment model with a mean (SEM) elimination half-life of 209 (29) min and total body clearance of 40.4 (3.6) ml min-1 kg-1. The mean (SEM) apparent volume of distribution at steady state was 5.0 (2.7) litre kg-1 and volume of the central compartment was 0.6 (0.1) litre kg-1. The mean (SEM) ratio of k12:k21 was 1.4 (0.2), suggesting that, after injection of a single bolus dose in children, propofol is distributed rapidly to the shallow compartment. The mean ratio of k31:k10 suggests that lipophilicity constrains return of the drug to the central compartment.
Anesthesia, Inhalation↗
Mortality of a cohort of tin miners 1941-86.
The mortality patterns of United Kingdom tin miners were examined in relation to calendar period and duration of underground work with particular attention to lung cancer and exposure to radon. Subjects were all men who had worked for at least one year between 1941 and 1984 at one of two United Kingdom tin mines and for whom a complete work history could be constructed from mine records. Standardised mortality ratios (SMRs) were calculated using national (England and Wales) rates. The pattern of SMRs in relation to potential explanatory variables was analysed using Poisson regression methods. Mortalities from lung cancer and silicosis (including silicotuberculosis) were significantly raised and showed a significant relation with duration of underground work (mortality from stomach cancer was raised in both underground and surface workers, but not significantly). Excess mortality from silica related disease declined steeply from 35% among workers first exposed before 1920 to 1% among those first exposed after 1950. Thirteen surface workers with known exposure to arsenic had high rates of lung and stomach cancer. The SMR for lung cancer showed a consistent pattern in relation to duration of underground exposure, rising from 83 (observed/expected = 8/9.6) for surface workers (without exposure to arsenic) to 447 (15/3.4) for workers with more than 30 years underground exposure. Examination of the SMR for lung cancer by total underground exposure, age, and time since last exposure gave rise to a model for the expression of risk which depends only on total exposure and time since exposure. The fitted model implies that the effect of exposure to radon in a given year has no effect on risk for 10 years, then rapidly rises to a maximum from which the excess risk then declines, halving every 4.3 years. There were no direct measurements of historic radon levels. A conservative estimate based on measurements taken since 1969 by the National Radiological Protection Board and the Mines and Quarries Inspectorate is that the annual dose to an underground worker was about 10 working level months (WLM). Given this assumption, the risk/exposure slope implied by the present data, and the model fitted to it, was somewhat lower than that given in the fourth Committee on the Biological Effects of Ionisation Radiation (BEIR IV) report (about 40% lower for lifetime exposures). The present data also imply different risks depending on the age at exposure, with relatively higher lifetime risks for exposure at older ages, and relatively lower risks for exposures at younger ages. In conclusion, there was a clear relation between exposure to radon and death from lung cancer. The relative risk of lung cancer due to exposure to radon was not constant in cessation of exposure. The lifetime excess risk of lung cancer implied by these data for 40 years exposure at the current statutory limit of four WLM a year starting at age 20, was about 8% (79 excess deaths per 1000 exposed), assuming average smoking habits among the exposed workers. Control of dust concentrations in the mines has substantially reduced--and may have eliminated--direct mortality from silica related disease.
Arsenic Poisoning↗
Effect of premedication on arterial blood gases prior to cardiac surgery.
The effect of premedication on arterial blood gas tensions was studied in thirty adult surgical patients with valvular disease. They were divided into three groups, each group having a different premedication regimen. Blood gas tensions were compared in these patients when awake on the night before surgery, asleep, after premedication and just prior to induction of anaesthesia. Samples were taken while the patient breathed air and each patient acted as his/her own control. The patients were randomised into one of three premedication regimens: 1. intramuscular lorazepam, 2. intramuscular morphine and hyoscine (scopolamine) and 3. oral lorazepam plus intramuscular morphine and hyoscine. There was a statistically significant though not clinically significant rise in PaCO2 and fall in pH following premedication with lorazepam, morphine and hyoscine. There was also a significant fall in PaO2 associated with morphine and hyoscine premedication which was greater than that which occurred with unsedated sleep. Patients who are to undergo cardiac valvular surgery should receive supplementary oxygen following premedication and during transfer to the operating room.
Administration, Oral↗
A comparison of lignocaine 2% with adrenaline 1:200,000 and lignocaine 2% with adrenaline 1:200,000 plus fentanyl as agents for caudal anaesthesia in children undergoing circumcision.
This randomised double-blind study compares the onset, quality and duration of analgesia in two groups of children (n = 30), aged between two and twelve years undergoing circumcision. Under concurrent general anaesthesia, the children received caudal anaesthesia employing either lignocaine 2% with adrenaline 1:200,000 plus normal saline 0.01 ml/kg, or lignocaine 2% with adrenaline 1:200,000 plus fentanyl 1.0 microgram/kg. The results show no statistical or clinical difference in the onset, duration, quality of pain relief, or side-effects between the two solutions.
Analgesia↗
Mortality of workers in the British cotton industry in 1968-1984.
The mortality of 3458 cotton industry workers originally enrolled in a study of respiratory symptoms in the period 1968-1970 was followed to the end of 1984. Both the total mortality and the mortality from respiratory disease were less than expected, and they both decreased as length of service increased. However, for the subjects who initially reported byssinotic symptoms, the mortality from respiratory disease was slightly raised overall, and it increased with length of service. These patterns of mortality indicate a survivor effect (ie, a tendency for those with respiratory weakness to leave the industry), together with a long-term effect reflected in respiratory mortality on the health of those workers susceptible to the effects of cotton dust. The mortality from lung cancer was lower than expected, and it decreased with length of service. This finding is consistent with other observations that exposure to cotton dust may reduce the risk of lung cancer.
Adolescent↗