Biomedical subjects
J T Wright
Publications and source records attributed to J T Wright.
The effect of phenylpropanolamine on ambulatory blood pressure.
Phenylpropanolamine (PPA) is a sympathomimetic amine and component of many over-the-counter decongestants and anorectic agents. It has been reported to cause elevated blood pressure and even hypertensive crises. The pressor effects with therapeutic doses are not well established. We monitored the effects of acute and chronic PPA dosing using 24-hour ambulatory blood pressure recording as a sensitive method of monitoring blood pressure variability. Eighteen normotensive male subjects were randomly assigned to receive 75 mg PPA (sustained-release preparation) or placebo in a double-blind crossover design with blood pressure monitored on days 1 (D1) and 6 (D6) of each period. There was no significant difference in blood pressure when compared as either 2-hour intervals or 24-hour global means: (placebo) 116/68 (D1), 117/68 (D6); (PPA) 118/69 (D1), 119/69 (D6). Our results document the absence of pressor effect with PPA in therapeutic doses even with repeated measurements and further confirm the reproducibility of 24-hour blood pressure monitoring.
The management of labour using continuous lumbar epidural analgesia in a patient with a malignant cerebral tumour.
A mother presented at 28 weeks with epileptiform convulsions which were due to a malignant cerebral tumour. Labour and delivery at 34 weeks were managed under epidural analgesia. The infant was healthy, but the mother died several days later following cerebral decompression.
Dental and craniofacial anomalies of Axenfeld-Rieger syndrome.
Apart from the three distinguishing findings for the diagnosis of Axenfeld-Rieger syndrome (oligodontia, failure of periumbilical skin to involute, and ocular anterior chamber defects), a common feature is midface hypoplasia. Two theories have been proposed to explain the midface hypoplasia. One theory suggests a pleiotropic gene effect of defective neural crest cells, while the other theory proposes that midface hypoplasia is a local effect due to the absence of teeth. This study presents an evaluation of the craniofacial defects in a family affected with Axenfeld-Rieger syndrome. The maxillary deficiency in three affected patients was not limited to the alveolar regions. We conclude that a combination of skeletal and dentoalveolar factors contributes to the midface hypoplasia associated with Axenfeld-Rieger syndrome.
Mouth protectors and oral trauma: a study of adolescent football players.
A total of 754 junior high school and high school football players from the Birmingham, AL, area were studied to determine the extent of sports-related oral trauma among players. More than half the oral injuries and more than a third of the concussions were reported in sports other than football. Basketball and baseball players had a high prevalence of hard tissue oral trauma with virtually none of the players wearing mouth protectors. The results of this study indicate that current mouth protector designs are helpful in preventing hard tissue trauma, yet additional soft tissue protection is indicated in football mouth protector design.
Labetalol by continuous intravenous infusion in severe hypertension.
This study documents our experience with labetalol administered by continuous intravenous infusion for severe hypertension. Infusions were performed in 14 hospitalized patients (15 infusions) with supine diastolic pressure greater than 125 mmHg or supine systolic pressure greater than 200 mmHg. Blood pressures were measured by intra-arterial recording or an Arteriosonde 1225 Doppler instrument standardized with a mercury sphygmomanometer. Patients initially received 2 mg/min continuous infusion; the infusion rate varied between 0.5 and 2.0 mg/min according to the protocol. The infusion was terminated when diastolic pressure decreased 30 mmHg or when 300 mg of the drug had been infused. Goal blood pressure was achieved in all but two infusions. Sedation was the most common adverse reaction, followed by nausea and diaphoresis. No patient required discontinuation or reduction in infusion rate secondary to side effects. We conclude that continuous intravenous infusion of labetalol offers an effective alternative to current parenteral therapy.
X-linked recessive hypohidrotic ectodermal dysplasia. Manifestations and management.
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The ultrastructure of the dental tissues in dentinogenesis imperfecta in man.
Eight primary incisors obtained from a child with dentinogenesis imperfecta (DI) type II were examined histologically using light microscopy and scanning electron microscopy. In both the DI and control teeth, large dentinal canals were observed along the midline of the crown distributed mesial-distally and coursing towards the pulp. Variably-structured mantle dentine was seen in the DI teeth ranging from tubular to virtually atubular. Enamel separation occurred at the dentine-enamel junction despite apparently normal scalloping. In the enamel, fractures occurred along accentuated striae of Retzius where ultrastructurally there was prism bending and discontinuity. The structure of DI teeth probably results from a structural or regulatory protein abnormality and irregular epithelial-mesenchymal interaction. The combined influence of these factors appears to cause variable histologic appearances and rates of tissue deposition.
Inhibition of platelet aggregation and thromboxane production by pinacidil.
We examined the effects of pinacidil on in vitro platelet function and arachidonic acid metabolism. Pinacidil is an arterial vasodilator currently undergoing clinical trials. Although its mechanism of action is yet undetermined, there is evidence that the activity of other vasodilators may in part be mediated through their effects on arachidonic acid metabolism. Alterations in platelet function were investigated by measuring ADP-induced aggregation in aliquots of human platelet rich plasma that were preincubated with pinacidil. Changes in arachidonic acid metabolism were determined using washed platelets incubated with 14C labeled arachidonic acid after preincubation with pinacidil or indomethacin. The arachidonate metabolites formed were extracted, separated by thin layer chromatography and quantitated via liquid scintillation spectrometry. Pinacidil inhibited platelet aggregation in a concentration dependent manner with 94% inhibition at 0.005M pinacidil. Pinacidil also caused concentration dependent inhibition of TXB2 production (63% inhibition at 0.01M) with reciprocal increases in PGE2 and PGF2 alpha production. There was no significant alteration in arachidonic acid utilization. Indomethacin (0.01M), as expected, inhibited TXB2 as well as PGE2 and PGF2 alpha synthesis. We conclude that, under the conditions of our assay, pinacidil inhibits platelet aggregation and specifically inhibits thromboxane synthetase, an action different from that of indomethacin. Alterations in the relative synthesis of vasodilating and vasoconstricting prostaglandins may be one mechanism whereby pinacidil exerts its antihypertensive activity.
Is bladder catheterization really necessary before laparoscopy?
A randomized prospective controlled trial compared a policy of bladder catheterization with no catheterization in patients undergoing laparoscopy. Of the 41 patients randomized to receive no catheterization, seven were actually catheterized on the judgement of the surgeon, but only one of them had greater than 50 ml of urine. Midstream urine obtained 6 days after laparoscopy was infected in 9 (21%) of the 42 patients allocated to receive catheterization and in only five (12%) of those allocated to the no-catheter group. Four of these five were actually not catheterized, giving an infection rate of 12% in the 34 patients not catheterized. The differences are statistically significant. A routine policy of catheterization for patients undergoing laparoscopy is questionable. All patients who are catheterized should be investigated for urinary tract infections after operation.
Analysis of a kindred with amelogenesis imperfecta.
Amelogenesis imperfecta (AI) is a group of hereditary disorders whose manifestations are generally considered as being confined to the teeth. Pedigree analysis of a kindred revealed 2 siblings affected with AI which was consistent with an autosomal recessive mode of inheritance. Cephalometric evaluation showed both children to have an obtuse gonial angle and steep mandibular plane. These skeletal changes were manifested as a severe anterior open bite. Histological evaluation of the teeth demonstrated numerous enamel changes including altered prism morphology, prism coalescence and disruption, globular inclusions, and irregular crystallite orientation. The clinical and histological data are consistent with autosomal recessive pigmented hypomaturation amelogenesis imperfecta. The enamel defects appear to be caused by the combination of decreased mineral deposition with abnormal crystallite and prism formation. Some areas of enamel hypoplasia seem to exist as well.
Effects of moderate alcohol consumption and smoking on fetal outcome.
Previous studies of the effects of moderate drinking on the outcome of pregnancy are assessed. The results of a prospective study of the association between alcohol consumption in pregnancy and birthweight, length of baby, head circumference and premature delivery are described. Consumption of more than 10 g alcohol per day in very early pregnancy or even before conception approximately doubled the risk that the infant would have a low birthweight. Cigarette smoking was also a risk factor for low birthweight. It may therefore be beneficial for women to reduce their alcohol consumption to one drink a day or less from before conception and give up smoking as well.
Epidermolysis bullosa: dental and anesthetic management of two cases.
Epidermolysis bullosa (EB) is a group of rare genetic disorders which are of dental interest because of their specific oral manifestations and management difficulties. Two cases of recessive EB which may be classified clinically as the atrophicans-gravis Herlitz type are described. Dental therapy consisted of extractions and stainless steel crown restorations, with inhalation general anesthesia. The need for and advantages of early preventive and restorative dental care are illustrated by the cases presented.
Laboratory evaluation of eight pit and fissure sealants.
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Microfilled composite restorative resins in pediatric dentistry.
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Moderate drinking during pregnancy and foetal outcome.
Although there are many reports of the adverse effects of alcohol on the infant in ancient literature the first modern report was by Sullivan, Physician to Liverpool gaol. He showed an increased incidence of growth retardation and stillbirth in children of alcoholic mothers using their non-drinking relatives as a control. The literature on moderate drinking is contradictory and suffers from poor control of factors known to confound pregnancy outcome such as social class, parity and smoking habit. The other major problem in assessing the effect of moderate drinking is the difficulty in obtaining accurate drinking histories and the many and varied ways in which these are taken. All histories however, should be regarded as an underestimate. Moderate drinking (less than 40 g alcohol/day before and during pregnancy) has been related to growth retardation, a higher incidence of congenital abnormality, poorer behavioural and neurological scores in the newborn. Recent American surveys have shown an increased relative risk of mid-trimester abortion in women who drink more than three times a week in early pregnancy. Recent work in this country has demonstrated a trend toward smaller head circumference and reduced weight in the babies born to mothers consuming more than 100 g alcohol a week in very early pregnancy. The interaction between smoking and drinking is particularly important for this effect. Using logistic regression analysis the effect of drinking and smoking on birth weight can be clearly seen together with the effect of social class. For any impact to be made on this problem educational intervention is necessary before pregnancy is planned, and thus should be directed at pre-conception clinics, family planning clinics and the general practitioner's surgery.
Drinking during pregnancy.
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