Regulation of human (adrenal) androgen biosynthesis-New insights from novel throughput technology studies

Androgens are precursors for sex steroids and are predominantly produced in the human gonads and the adrenal cortex. They are important for intrauterine and postnatal sexual development and human reproduction. Although human androgen biosynthesis has been extensively studied in the past, exact mechanisms underlying the regulation of androgen production in health and disease remain vague. Here, the knowledge on human androgen biosynthesis and regulation is reviewed with a special focus on human adrenal androgen production and the hyperandrogenic disorder of polycystic ovary syndrome (PCOS). Since human androgen regulation is highly specific without a good animal model, most studies are performed on patients harboring inborn errors of androgen biosynthesis, on human biomaterials and human (tumor) cell models. In the past, most studies used a candidate gene approach while newer studies use high throughput technologies to identify novel regulators of androgen biosynthesis. Using genome wide association studies on cohorts of patients, novel PCOS candidate genes have been recently described. Variant 2 of the DENND1A gene was found overexpressed in PCOS theca cells and confirmed to enhance androgen production. Transcriptome profiling of dissected adrenal zones established a role for BMP4 in androgen synthesis. Similarly, transcriptome analysis of human adrenal NCI-H295 cells identified novel regulators of androgen production. Kinase p38α (MAPK14) was found to phosphorylate CYP17 for enhanced 17,20 lyase activity and RARB and ANGPTL1 were detected in novel networks regulating androgens. The discovery of novel players for androgen biosynthesis is of clinical significance as it provides targets for diagnostic and therapeutic use.

Mechanism-based inhibition of the melatonin rhythm enzyme: Pharmacologic exploitation of active site functional plasticity

Serotonin N-acetyltransferase is the enzyme responsible for the diurnal rhythm of melatonin production in the pineal gland of animals and humans. Inhibitors of this enzyme active in cell culture have not been reported previously. The compound N-bromoacetyltryptamine was shown to be a potent inhibitor of this enzyme in vitro and in a pineal cell culture assay (IC50 ≈ 500 nM). The mechanism of inhibition is suggested to involve a serotonin N-acetyltransferase-catalyzed alkylation reaction between N-bromoacetyltryptamine and reduced CoA, resulting in the production of a tight-binding bisubstrate analog inhibitor. This alkyltransferase activity is apparently catalyzed at a functionally distinct site compared with the acetyltransferase activity active site on serotonin N-acetyltransferase. Such active site plasticity is suggested to result from a subtle conformational alteration in the protein. This plasticity allows for an unusual form of mechanism-based inhibition with multiple turnovers, resulting in “molecular fratricide.” N-bromoacetyltryptamine should serve as a useful tool for dissecting the role of melatonin in circadian rhythm as well as a potential lead compound for therapeutic use in mood and sleep disorders.

Structure of the HIV-1 integrase catalytic domain complexed with an inhibitor: A platform for antiviral drug design

HIV integrase, the enzyme that inserts the viral DNA into the host chromosome, has no mammalian counterpart, making it an attractive target for antiviral drug design. As one of the three enzymes produced by HIV, it can be expected that inhibitors of this enzyme will complement the therapeutic use of HIV protease and reverse transcriptase inhibitors. We have determined the structure of a complex of the HIV-1 integrase core domain with a novel inhibitor, 5ClTEP, 1-(5-chloroindol-3-yl)-3-hydroxy-3-(2H-tetrazol-5-yl)-propenone, to 2.1-Å resolution. The inhibitor binds centrally in the active site of the integrase and makes a number of close contacts with the protein. Only minor changes in the protein accompany inhibitor binding. This inhibitor complex will provide a platform for structure-based design of an additional class of inhibitors for antiviral therapy.

Rescue of abasic hammerhead ribozymes by exogenous addition of specific bases.

We have synthesized 13 hammerhead ribozyme variants, each containing an abasic residue at a specific position of the catalytic core. The activity of each of the variants is significantly reduced. In four cases, however, activity can be rescued by exogenous addition of the missing base. For one variant, the rescue is 300-fold; for another, the rescue is to the wild-type level. This latter abasic variant (G10.1X) has been characterized in detail. Activation is specific for guanine, the base initially removed. In addition, the specificity for guanine versus adenine is substantially altered by replacing C with U in the opposite strand of the ribozyme. These results show that a binding site for a small, noncharged ligand can be created in a preexisting ribozyme structure. This has implications for structure-function analysis of RNA, and leads to speculations about evolution in an "RNA world" and about the potential therapeutic use of ribozymes.

Oligodeoxynucleotides inhibit retinal neovascularization in a murine model of proliferative retinopathy.

Diseases characterized by retinal neovascularization are among the principal causes of visual loss worldwide. The hypoxia-stimulated expression of vascular endothelial growth factor (VEGF) has been implicated in the proliferation of new blood vessels. We have investigated the use of antisense phosphorothioate oligodeoxynucleotides against murine VEGF to inhibit retinal neovascularization and VEGF synthesis in a murine model of proliferative retinopathy. Intravitreal injections of two different antisense phosphorothioate oligodeoxynucleotides prior to the onset of proliferative retinopathy reduced new blood vessel growth a mean of 25 and 31% compared with controls. This inhibition was dependent on the concentration of antisense phosphorothioate oligodeoxynucleotides and resulted in a 40-66% reduction in the level of VEGF protein, as determined by Western blot analysis. Control (sense, nonspecific) phosphorothioate oligodeoxynucleotides did not cause a significant reduction in retinal neovascularization or VEGF protein levels. These data further establish a fundamental role for VEGF expression in ischemia-induced proliferative retinopathies and a potential therapeutic use for antisense phosphorothioate oligodeoxynucleotides.

Commonplace book of Moses Appleton, 1791-1815 (inclusive)

Volume containing medicinal recipes, medical notes, poetry, and obituaries written by Dr. Moses Appleton (1773-1849). Many of the recipes were copied from medical texts or other publications. His "cure for the dropsy," taken from the New York Herald, contained stale cider, parsley, horseradish, oxymel squills (sea onion in honey), and juniper berries. For diarrhea, he prescribed a blackberry syrup. Several entries indicate Appleton practiced Thomsonian medicine, an alternative system based on use of botanicals. The medical notes include an account of his treatment of a man with smallpox in 1815, and entries on patients he inoculated with cowpox matter. Another entry dated in 1796 provides instructions from the Massachusetts Humane Society for "treatment to be used with persons apparently dead from drowning," which included blowing tobacco smoke in the victim's lungs and applying warm blankets for several hours. Appleton adds a note questioning whether or not the lungs also should be "often artificially inflated." There is additionally a history of prominent physicians dating from ancient Greece.

Cases copied by James Lloyd from Mr. Steed, apothecary in Guy's Hospital, London, 1751-1787 (inclusive)

Contains medical cases copied by James Lloyd (1728-1810), primarily between 1751 and 1754, from Mr. Steed, an apothecary at Guy's Hospital in London, England. The volume has additional medical cases dating from 1780 to 1787. Lloyd transcribed the names, ages, and symptoms of the patients, as well as the medicines and medical care delivered to them. The volume is divided into chapters based on the type of case, which included vision loss; fluor albus, or leucorrhoea; diabetes; and dysentery. There is also a letter pasted into the volume addressed to Dr. Brigham of the Boston Medical Library Association from Lloyd's great-grandson, dated 4 November 1887.

A vitamina D na diabetes mellitus tipo 2 : uma forma terapêutica a explorar

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Treatment of partial-thickness burns: A prospective, randomized trial using Transcyte (TM)

Background: The purpose of the present study was to compare the effectiveness of three burns dressings (TransCyte, a bio-engineered skin substitute; Biobrane; and Silvazine cream (silver sulphadiazine and 0.2% chlorhexidine)), in treating children with partial-thickness burns. The primary objective was to determine the days until greater than or equal to90% re-epithelialization. The secondary objectives were to evaluate the number of wounds requiring autografting and the number of dressing changes/local wound care required. Methods: Study wounds were identified on each patient and the patients were randomized to receive TransCyte or Biobrane or Silvazine. Assessment of study wound closure began at 2 days after treatment and continued at least every other day thereafter until the wounds re-epithelialized or were autografted. A laser Doppler imaging system was used as an adjunct to assessing the depth of the burn. Results: Thirty-three patients with 58 wound sites enrolled in the study (TransCyte, n = 20, Biobrane, n = 17; Silvazine, n = 21). Mean time to re-epithelialization was 7.5 days for TransCyte, 9.5 days for Biobrane, and 11.2 days for Silvazine. The number of wounds requiring autografting were 5/21 (24%) for Silvazine, 3/17 (17%) for Biobrane, and 1/20 (5%) for TransCyte. Conclusions: When used in partial-thickness burns in children, TransCyte promotes fastest re-epithelialization and required less overall dressings then Biobrane or Silvazine. Patients who received Silvazine or Biobrane require more autografting than those treated with TransCyte.

Prostanoids as friends, not foes: Further evidence from the interference by cycloxygenase-inhibitory drugs when inducing tolerance to experimental arthritigens in rats

Pharmacologists have generally been prejudiced against prostanoids, uncritically accepting their suppression as desirable therapy, especially for ‘quick-fix’ analgesia. This myopic perception for a long time ignored (a) the essentiality of prostanoid precursors in nutrition, (b) the physiological protective functions of natural prostaglandins (PGs) (vasculature, stomach, kidney), (c) resolution of inflammation after the expression of COX-2 and (d) increasing therapeutic use of either synthetic PGs (for erectile dysfunction, opthalmic disorders, inducing parturition, etc) or their natural precursors, e.g., ω3-rich polyunsaturated oils, to treat arthritis. Experimental studies in rats have indicated that prostaglandins (E series) are (i) useful, perhaps auto-regulators of established immunoreactivity and (ii) able to amplify (or even induce) anti-inflammatory activity with other agents. Furthermore, anti-prostanoid therapy (APT) can be arthritigenic!!, interfering with the acquisition of tolerance to some arthritigens. For patients with rheumatoid arthritis this additional side-effect of APT, barely recognised to date, may actually perpetuate their arthritis by impairing prostanoid-mediated remission processes. Hopefully, recent adverse publicity about COX-2 inhibitory drugs might stimulate serious re-assessment of some traditional anti-inflammatory therapies with low APT activity for the management of both acute pain (non-addictive cannabinoids, celery seed, etc.) and chronic inflammation, e.g., Lyprinol® (a mussel lipid extract).

Pregabalin - learning from gabapentin?

The author overviews the use of pregabalin in neuropathic pain. (non-author abstract)

Survival strategy of Echinococcus multilocularis in the human host

As exemplified by aborted calcified liver lesions commonly found in patients from endemic areas, Echinococcus multilocularis metacestodes develop only in a minority of individuals exposed to infection with the papasite. Clinical research has disclosed some aspects of the survival strategy of E. multilocularis in human hosts. Clinical observations in liver transplantation and AIDS suggest that suppression of cellular/Th1related immunity increases disease severity. Most of the studies have stressed a role for CD8+ T cells and for Interleukin-10 in the development of tolerance. A spontaneous secretion of IL-10 by the PBMC seems to be the immunological hallmark of patients with progressive forms of alveolar echinococcosis (AE). IL-10-induced inhibition of effector macrophages, but also of antigen-presenting dendritic cells, may be operating and allowing parasite growth and survival. The genetic correlates of susceptibility to infection with E. multilocularis are clearer in humans than in the mouse model. A significant link between MHC polymorphism and clinical presentation of AE has been shown, and the spontaneous secretion of IL-10 in patients with a progressive AE is higher in patients with the HLA DR3+, DQ2+ haplotype. Clustering of cases in certain families, in communities otherwise exposed to similar risk factors, also points to immuno-genetic predisposition factors that may allow the larva to escape host immunity more easily. The first stage of larval development may be crucial in producing danger signals stimulating the initial production of cytokines. Therapeutic use of Interferon alpha is an attempt to foil the survival strategy of E. multilocularis. (C) 2005 Elsevier Ireland Ltd. All rights reserved.