Virginia Commonwealth University

About: Virginia Commonwealth University is a education organization based out in Richmond, Virginia, United States. It is known for research contribution in the topics: Population & Health care. The organization has 23822 authors who have published 49587 publications receiving 1787046 citations. The organization is also known as: VCU.

Metformin for the treatment of the polycystic ovary syndrome.

Abstract: A 23-year-old woman with known polycystic ovary syndrome visits her family physician. She has taken oral contraceptive pills in the past but did not tolerate them and is not currently receiving any treatment. She has three or four menstrual periods per year and is not interested in becoming pregnant now, but she will be getting married in a year. She has heard that the polycystic ovary syndrome is associated with diabetes and is concerned because both her mother and father have type 2 diabetes. Her bodymass index (the weight in kilograms divided by the square of the height in meters) is 32, her waist circumference is 38 in. (96.5 cm), her serum total testosterone level is elevated at 0.9 ng per milliliter (90 ng per deciliter, or 2.9 nmol per liter), her plasma high-density lipoprotein cholesterol level is 35 mg per deciliter (0.9 mmol per liter), and her triglyceride level is 190 mg per deciliter (2.1 mmol per liter). Her serum glucose level 2 hours after the ingestion of 75 g of dextrose is 138 mg per deciliter (7.7 mmol per liter). The physician wonders whether treatment with metformin would be beneficial and refers the patient to an endocrinologist. T h e C l i nic a l Probl e m The polycystic ovary syndrome is a clinical diagnosis characterized by the presence of two or more of the following features: chronic oligo-ovulation or anovulation, androgen excess, and polycystic ovaries. 1 It affects 5 to 10% of women of childbearing age 2,3 and is the most common cause of anovulatory infertility in developed countries. Common clinical manifestations include menstrual irregularities and signs of androgen excess such as hirsutism, acne, and alopecia. The polycystic ovary syndrome is associated with important metabolic derangements. The prevalence of type 2 diabetes in the United States is 10 times as high among young women with the polycystic ovary syndrome as among normal women, 4,5 and impaired glucose tolerance or overt type 2 diabetes develops by the age of 30 years in 30 to 50% of obese women with the polycystic ovary syndrome. 4‑6 The prevalence of the metabolic syndrome is two to three times as high among women with the polycystic ovary syndrome as among normal women matched for age and body-mass index, and 20% of women with the polycystic ovary syndrome who are younger than 20 years of age have the metabolic syndrome. 7 Although outcome data specifically for women with the polycystic ovary syndrome are lacking, the risk of fatal myocardial infarction is twice as high among women with severe oligomenorrhea, most of whom would be expected to have the polycystic ovary syndrome, as among women with eumenorrhea. 8 This Journal feature begins with a case vignette that includes a therapeutic recommendation. A discussion of the clinical problem and the mechanism of benefit of this form of therapy follows. Major clinical studies, the clinical use of this therapy, and potential adverse effects are reviewed. Relevant formal guidelines, if they exist, are presented. The article ends with the author’s clinical recommendations.

A 1.5 million-base pair inversion polymorphism in families with Williams-Beuren syndrome.

Abstract: Williams-Beuren syndrome (WBS) is most often caused by hemizygous deletion of a 1.5-Mb interval encompassing at least 17 genes at 7q11.23 (refs. 1,2). As with many other haploinsufficiency diseases, the mechanism underlying the WBS deletion is thought to be unequal meiotic recombination, probably mediated by the highly homologous DNA that flanks the commonly deleted region3. Here, we report the use of interphase fluorescence in situ hybridization (FISH) and pulsed-field gel electrophoresis (PFGE) to identify a genomic polymorphism in families with WBS, consisting of an inversion of the WBS region. We have observed that the inversion is hemizygous in 3 of 11 (27%) atypical affected individuals who show a subset of the WBS phenotypic spectrum but do not carry the typical WBS microdeletion. Two of these individuals also have a parent who carries the inversion. In addition, in 4 of 12 (33%) families with a proband carrying the WBS deletion, we observed the inversion exclusively in the parent transmitting the disease-related chromosome. These results suggest the presence of a newly identified genomic variant within the population that may be associated with the disease. It may result in predisposition to primarily WBS-causing microdeletions, but may also cause translocations and inversions.

Determining parameters for respiration-gated radiotherapy.

Abstract: Respiration-gated radiotherapy for tumor sites affected by respiratory motion will potentially improve radiotherapy outcomes by allowing reduced treatment margins leading to decreased complication rates and/or increased tumorcontrol. Furthermore, for intensity-modulated radiotherapy(IMRT), respiratory gating will minimize the hot and cold spot artifacts in dose distributions that may occur as a result of interplay between respiratory motion and leaf motion. Most implementations of respiration gating rely on the real time knowledge of the relative position of the internal anatomy being treated with respect to that of an external marker. A method to determine the amplitude of motion and account for any difference in phase between the internal tumor motion and external marker motion has been developed. Treating patients using gating requires several clinical decisions, such as whether to gate during inhale or exhale, whether to use phase or amplitude tracking of the respiratory signal, and by how much the intrafraction tumor motion can be decreased at the cost of increased delivery time. These parameters may change from patient to patient. A method has been developed to provide the data necessary to make decisions as to the CTV to PTV margins to apply to a gated treatment plan.

Radioligand binding evidence implicates the brain 5-HT2 receptor as a site of action for LSD and phenylisopropylamine hallucinogens

Abstract: Alterations in brain serotonergic function have been implicated in the mechanism of action of LSD, mescaline, and other similarly acting hallucinogenic drugs of abuse such as STP (2,5-dimethoxyphenylisopropylamine; DOM). In order to test the hypothesis that the mechanism of action of LSD and phenylisopropylamine hallucinogens is through stimulation of a specific brain serotonin receptor sub-type, the affinities of these compounds for radiolabelled 5-HT2, 5-HT1A, 5-HT1B, and 5-HT1C receptors have been determined using recently developed in vitro radioligand binding methodologies. The 5-HT2 receptor was labelled with the agonist/hallucinogen radioligand 3H-DOB (4-bromo-2,5-dimethoxyphenylisopropylamine). The 5-HT1A, 5-HT1B, and 5-HT1C receptors were labelled with 3H-OH-DPAT, 3H-5-HT, and 3H-mesulergine, respectively. In general, the phenylisopropylamines displayed 10–100 fold higher affinities for the 5-HT2 receptor than for the 5-HT1C receptor and 100–1000 fold higher affinities for the 5-HT2 receptor than for the 5-HT1A or 5-HT1B receptor. There was a strong correlation between hallucinogenic potencies and 5-HT2 receptor affinities of the phenylisopropylamines (r=0.90); the correlation coefficients for the 5-HT1A, 5-HT1B, and 5-HT1C were 0.73, 0.85, and 0.78, respectively. Because there is no evidence that 5-HT1A-selective or 5-HT1B-selective agonists are hallucinogenic and because the phenylisopropylamines are potent hallucinogens, a 5-HT2 receptor interaction is implicated and supports our previous suggestions to this effect. A secondary role for 5-HT1C receptors cannot be discounted at this time. These results, when integrated with other receptor pharmacological information, indicate that an important component of the mechanism of action of LSD and the phenylisopropylamine hallucinogens is through stimulation of brain 5-HT2 receptors.

CB2 receptors in the brain: role in central immune function

Abstract: Recently, it has been recognized that the cannabinoid receptor CB2 may play a functionally relevant role in the central nervous system (CNS). This role is mediated primarily through microglia, a resident population of cells in the CNS that is morphologically, phenotypically, and functionally related to macrophages. These cells also express the cannabinoid receptor CB1. The CB1 receptor (CB1R) is constitutively expressed at low levels while the CB2 receptor (CB2R) is expressed at higher levels and is modulated in relation to cell activation state. The relatively high levels of the CB2R correspond with microglia being in ‘responsive' and ‘primed' states, suggesting the existence of a ‘window' of functional relevance during which activation of the CB2R modulates microglial activities. Signature activities of ‘responsive' and ‘primed' microglia are chemotaxis and antigen processing, respectively. The endocannabinoid 2-arachidonylglycerol has been reported to stimulate a chemotactic response from these cells through the CB2R. In contrast, we have shown in vivo and in vitro that the exogenous cannabinoids delta-9-tetrahydrocannabinol and CP55940 inhibit the chemotactic response of microglia to Acanthamoeba culbertsoni, an opportunistic pathogen that is the causative agent of Granulomatous Amoebic Encephalitis, through activation of the CB2R. It is postulated that these exogenous cannabinoids superimpose an inhibitory effect on pro-chemotactic endocannabinoids that are elicited in response to Acanthamoeba. Furthermore, the collective results suggest that the CB2R plays a critical immune functional role in the CNS.