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Biomedical subjects

L Edwards

Publications and source records attributed to L Edwards.

At least 55 records · Page 3Linked to original sources

Urinary diluting capacity in elderly diabetic subjects.

Urinary concentrating ability declines with normal human aging but diluting capacity has been less well studied as a function of age. We studied free water clearance (CH2O) in a group of Type II diabetic patients, aged 47 to 70 years. Conventional water load testing in sulfonylurea-treated diabetic patients revealed preservation of diluting capacity (ability to achieve Uosm less than 100 mOsm/kg) in subjects greater than 60 years of age. Tolazamide permitted expression of normal CH2O; chlorpropamide administration predictably reduced CH2O relative to tolazamide by 58% in subjects greater than 60 years. Free water clearance (CH2O) and glomerular filtration rate (GFR) were comparable in elderly subjects (greater than 60 years) and those less than or equal to 60 years. Normal CH2O in these diabetic patients was explained by persistently normal GFR in the study group. Osmolar clearance (Cosm) was insignificantly lower in diabetics greater than 60 years. Thus, a fall in CH2O in elderly diabetic patients is not a factor contributing to clinical hypoosmolar states encountered in this population.

Aged

Role of topical tretinoin in melanoma and dysplastic nevi.

The retinoids have been investigated extensively as chemopreventive and therapeutic agents in a variety of neoplasms. They have been shown to inhibit the proliferation of transformed cell lines in vitro and transplanted tumors in vivo. In cultured murine melanoma cells, retinoids inhibit proliferation and induce differentiation. Human melanoma cell lines have shown a mixed response. The clinical experience with retinoids in melanoma has been limited. Previously we investigated the activity of topical B-all-trans-retinoic acid (Retin-A, vitamin A acid, retinoic acid, and tretinoin) against intracutaneous metastases from malignant melanoma. We saw complete remission of multiple lesions in one individual and regression of several lesions in a second patient. This experience led us to conduct the present pilot trial of topical tretinoin in dysplastic nevus syndrome. The latter is a precursor of malignant melanoma. We saw regression of some of the treated lesions to benign nevi showing minimal or no dysplasia. Thus topical tretinoin appears to possess some activity against melanoma and at least one of its precursor conditions. In view of these preliminary results, more extensive trials are warranted to better define the role of tretinoin in the chemoprevention of malignant melanoma in high-risk lesions.

Administration, Topical

Effect of intralesional alpha 2-interferon on actinic keratoses.

The effect of intralesional alpha 2-interferon (IFN) on actinic keratoses was examined in this two-part study. In phase I, 11 of 12 lesions cleared following nine injections of IFN (5 X 10(5) IU per dose) compared with none of 12 keratoses injected with placebo. Smaller doses of IFN (1 X 10(5) IU and 1 X 10(4) IU per injection) produced clearing of 42% and 58% of lesions, respectively. The second phase, which was designed to investigate the optimum schedule for treatment with IFN, showed that a minimum of six injections of IFN (5 X 10(5) IU per injection) was necessary to clear 14 of 15 actinic keratoses. Although this mode of delivery is not practical for clinical use, intralesional alpha 2-IFN demonstrates biologic activity against actinic keratoses.

Adult

Randomised controlled study of orchidectomy vs long-acting D-Trp-6-LHRH microcapsules in advanced prostatic carcinoma.

Safety and efficacy of a slow-release formulation of D-Trp-6-luteinising-hormone-releasing-hormone (D-Trp-6-LHRH) microcapsules were compared with orchidectomy in the initial treatment of advanced prostatic carcinoma. 41 patients were randomly assigned to D-Trp-6-LHRH and 38 to orchidectomy. Suppression of testosterone and reduction in prostatic acid phosphatase levels were similar in both groups. 87% of patients in the D-Trp-6-LHRH group and 81% in the orchidectomy group responded to treatment or showed no deterioration. Side-effects related to the decrease in testosterone were similar in both groups. 3 patients given D-Trp-6-LHRH had a disease "flare" in the first ten days of treatment which resolved completely when testosterone fell to castrate levels. Results of psychological assessment were similar in both groups before treatment, and on follow-up there was a weak trend towards decreased psychological morbidity in the hormone group. The slow-release preparation of D-Trp-6-LHRH microcapsules offers an important alternative in the management of advanced prostatic carcinoma.

Aged

Source derivation of the brain-stem auditory evoked potential.

This study described the results of applying source derivation to the brain-stem auditory evoked potential. Unilateral stimulation gives rise to current sinks, associated with waves I and III, which are located in the vicinity of the ipsilateral mastoid. Waves II and V are associated with a pair of current sinks which appear bilaterally in the vicinity of each mastoid.

Adult

Case report of prolactin and bipolar illness: a longitudinal study.

A longitudinal and naturalistic study of nine bipolar patients attending a lithium clinic during a six-month period was undertaken. Prolactin plasma levels and psychiatric symptoms were evaluated bi-weekly. Wide interindividual and intraindividual fluctuations were observed both in prolactin levels and psychiatric symptoms. The relationship between prolactin and affective episodes was found to be complex. In a few instances, sharp prolactin changes preceded behavioral modifications. Bipolar disorders, even if treated, appeared to be unstable conditions, from both the phenomenological and neuroendocrinological viewpoints.

Adult

The use of a platelet nucleotide assay as a possible diagnostic test for malignant hyperthermia.

A bioassay, using high-performance liquid chromatography (HPLC) analysis of platelet adenosine nucleotides and hypoxanthine, was studied for its potential use as a test for MH susceptibility. A protocol for the assay was developed, based on the method outlined by Solomons and Masson. The HPLC procedure was a rapid, efficient, sensitive, and highly reproducible technique for measuring ATP, ADP, AMP, and hypoxanthine in platelets. Conditions of extraction and storage were critical for preventing degradation of the nucleotides. Extraction of nucleotides at icebath temperature was found necessary. Storage of platelet extract in PCA, even at -20 degrees C, showed loss of ATP and ADP; hence, neutralization with KOH was essential before storage. Contrary to the findings of Solomons et al., the present study demonstrated that neither ATP depletion nor per cent reduction in nucleotide ratios in platelets treated with halothane can be used as a definitive test for the diagnosis of MH susceptibility. The reason for this disagreement is unclear; however, differences in methods and altitude are implicated. It is possible that the platelet is not affected by malignant hyperthermia and thus cannot serve as a test system for the detection of the syndrome.

Adenine Nucleotides

Indole amines and amino acids in various brain regions after infusion of branched chain amino acids into hepatectomized rats.

This study was designed to determine regional changes of amino acids and indole amines in the brain and possible interactions between amino acids and indole amines 18 h after hepatectomy in rats. Hepatectomy and glucose infusion alone resulted in a profound increase of most large neutral amino acids (LNAA) in plasma and in the brain except for the branched-chain amino acids (BCAA), which maintained normal or somewhat lower values in plasma. Hepatectomy and infusion of glucose combined with BCAA sharply reduced the plasma and brain amino acid concentrations of other LNAA. Simultaneously the concentrations of serotonin and 5-hydroxyindoleacetic acid were decreased in all brain regions. In both groups of hepatectomized rats there were regional variations of the amino acid and the indole amine concentrations in the brain, but the response to BCAA infusion was generally the same in all brain regions. No difference in survival between the 2 groups could be found.

Amino Acids

Interstitial cystitis.

Twenty histologically proven cases of interstitial cystitis were investigated in an attempt to find evidence of a possible autoimmune mechanism in its aetiology. HLA tissue typing was performed, autoantibody profiles were obtained, and a questionnaire of the patients' past history completed, especially with respect to other autoimmune conditions. An experiment was designed to test the effect of sodium cromoglycate on rat bladders. The results are discussed in relation to the management of patients with interstitial cystitis.

Aged

Endourethral urethroplasty.

Following internal urethrotomy for treatment of strictures of the bulbous urethra, 11 patients had primary split skin grafts inlaid over the urethrotomy site. There were no operative complications and the results in 5 patients with a 9-month follow-up are good.

Adult