Biomedical subjects
J Dickerson
Publications and source records attributed to J Dickerson.
Liver function tests and low-dose estrogen oral contraceptives.
Twenty healthy female volunteers were treated with 35 microgram ethinyl estradiol and 0.4 mg norethindrone for a two-month period of time. Liver function tests (serum SGOT, SGPT, LDH, alkaline phosphatase, total bilirubin, total protein, albumin and prothrombin times) were measured at baseline and control prior to treatment, and at one and two months of therapy. There was a 1.25% incidence of abnormalities in the 320 tests conducted during therapy. During the first month of therapy, there was a 1.9% incidence of abnormal tests. 0.625% incidence of abnormal tests was seen in the second month of treatment. A 5% incidence of abnormalities (single episodes in each parameter) was seen in SGPT, LDH, total bilirubin and prothrombin time levels during the two-month period. This was well below the 10-30% incidence of abnormalities reported with 50-100 microgram of estrogen-containing birth control pills in previous studies. There seems to be little effect on liver function tests with use of estrogen preparations containing 35 microgram ethinyl estradiol.
Efficacy of estradiol vaginal cream in postmenopausal women.
In a double-blind parallel study daily intravaginal administration of conjugated estrogen cream and estradiol cream for 14 days relieved vasomotor and vaginal postmenopausal symptoms in 29 postmenopausal women. By day 14, therapy with the estradiol vaginal cream resulted in plasma estrone and estradiol levels closer to those in premenopausal women than therapy with the conjugated estrogen cream. The extent of improvement and final estradiol plasma levels in the estradiol vaginal-cream group correlated. There was no correlation with severity of symptoms or estradiol plasma level at baseline. The metabolism of the conjugated estrogen cream might account for absence of correlation between improvement and final estradiol plasma levels in the conjugated vaginal-cream group.
Dose tolerance and pharmacokinetic studies of L (+) pseudoephedrine capsules in man.
Dose tolerance and pharmacokinetic studies of pseudoephedrine sustained action capsules were performed in thirty-three adult male subjects who received either 120 mg or 150 mg capsules every twelve hours for seven consecutive days in a double-blind parallel design study. Although only one subject in the 150 mg group was discontinued prematurely from this study, a large number of side effects typical of CNS stimulation were seen. A placebo effect might account for a portion of these complaints, however symptoms evaluated as being due to drug were significantly more severe and persistent in the 150 mg group. Pulse rates showed a persistent and significant increase while systolic and diastolic blood pressure fell from the baseline values in both groups. A pharmacokinetic analysis of the pseudoephedrine plasma concentration-time data provided estimates of half-life and the volume of distribution/availability ratio. The values obtained were in good agreement with values reported by others. Half-life was not influenced by urine pH probably as a result of the narrow range of urine pHs observed in the subjects. Calculations of relative bioavailability suggest that the 120 mg capsule formulation has a 30% greater bioavailability compared to the 150 mg capsule.
Digoxin bioavailability: formulations and rates of infusions.
The bioavailability of digoxin (lanoxin) tablets, oral aqueous solution of digoxin, and capsules containing a solution of digoxin was compared with digoxin given intravenously over 1 and 3 hr. The mean peak serum concentration of digoxin after the 1-hr intravenous infusion was 5 ng/ml, after the 3-hr infusion, 3.5 ng/ml, and after the oral solution, 2.0 ng/ml. There was an equivalent bioavailability of the oral solution and reference tablets of digoxin. The digoxin in capsules tended to be better absorbed than the reference tablets. There was 21% more digoxin excreted over 6 days after the 3 hr iv infusion than after the 1 hr iv infusion. This indicates that the calculated bioavailability of an orally administered dose of digoxin may vary with the rapidity of injection of the intravenous standard. It is estimated that an oral tablet of digoxin of 0.5 mg has about the same bioavailability as 0.35 of digoxin given by slow intravenous infusion (or 0.4 mg if calculated against a rapid intravenous injection).
Pharmacokinetics of 14C-etretinate in healthy volunteers and two patients with biliary T-tube drainage.
The pharmacokinetic profile of 14C-etretinate, a retinoid that is effective in the treatment of psoriasis, was studied in six healthy male volunteers and two biliary T-tube patients. Following a 100 mg oral dose of 14C-etretinate (20 microcurie), etretinate and its major blood metabolites (etretin, isoetretin) were measured by HPLC and total carbon-14 was measured in blood, bile, urine, and feces by liquid scintillation counting. Etretinate was extensively metabolized in healthy volunteers and in T-tube patients. During the absorption phase, 75 per cent of the total radioactivity in the blood could be accounted for as etretinate, etretin, and isoetretin whereas these compounds accounted for only approximately 12 per cent of the blood radioactivity in T-tube patients over the same time period. The blood concentrations of etretinate, etretin, and isoetretin appeared to be substantially reduced in T-tube patients compared to those in healthy volunteers. A higher proportion of the total drug was excreted in the feces and bile of the T-tube patients (84 per cent) than in the feces of healthy volunteers (62 per cent). The major factor responsible for the observed decrease in etretinate blood concentrations following biliary cannulation appears to be the reduced absorption of etretinate due to the elimination of solubilizing bile salts in the duodenum. Carbon-14 related material was detected in urine and feces for as long as 3 weeks in healthy subjects supporting the previous observation that a long terminal elimination half-life exists for etretinate, even following a single dose of the compound.
The Neurobehavioural Rating Scale: replication in an acute, inpatient rehabilitation setting.
The Neurobehavioural Rating Scale (NRS) was developed to allow quantification of clinical observations of the behaviour of individuals following traumatic head injury. Initial validation of this instrument reported satisfactory interobserver reliability, as well as preliminary support for its validity in differentiating both severity and chronicity of head injury. In the present study, reliability and content validity of the NRS were replicated using a population of severe head injury patients undergoing inpatient rehabilitation. Concurrent, independent assessment using the NRS was conducted weekly by two members of an inpatient, traumatic head injury team. Acceptable levels of interobserver reliability were found, despite less control over observed behaviour in the naturalistic setting used. Content validity was also supported in this replication, although recommendations for 'tightening' the NRS included better definition of the seven-point severity rating for each item, as well as potential deletion of two items that contributed little to differential variance in the total NRS score. The NRS appears to be a promising clinical and research tool for assessing the neurobehavioural sequelae of traumatic head injury. Its strengths include efficiency of administration and the flexibility to administer through brief, structured interviews or observations in a naturalistic setting. Continued research on the NRS in different settings and with different populations is required to establish its validity.
An increase in hookworm infection temporally associated with ecologic change.
This report describes a significant increase in the prevalence of hookworm infection in an area of Haiti where intestinal parasites are common, but hookworm has not been common. Changing environmental conditions, specifically deforestation and subsequent silting of a local river, have caused periodic flooding with deposition of a layer of sandy loam topsoil and increased soil moisture. We speculate that these conditions, conducive to transmission of the infection, have allowed hookworm to reemerge as an important human pathogen.
Administering total parenteral nutrition.
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Comparison of dental crown height in bite impressions.
A wax bite impression can serve as a reliable identification of missing and unknown children, particularly in the absence of caries and restorations. Dental crown heights in bite impressions made from noncontoured and contoured wax wafers were compared in ten patients, ranging in age from three to eight years. The contoured wax wafer produced significantly greater crown heights in the casts which were fabricated from it. The differences were most pronounced in the anterior teeth; but generally true for all the teeth.
The problem of hospital-induced malnutrition.
This paper discusses the problem of hospital-induced malnutrition. Patients particularly at risk are identified and the causes of PEM are outlined.