Location of the dsRNA-dependent polymerase, VP1, in rotavirus particles

Double-stranded RNA (dsRNA) viruses transcribe and replicate RNA within an assembled, inner capsid particle; only plus-sense mRNA emerges into the intracellular milieu. During infectious entry of a rotavirus particle, the outer layer of its three-layer structure dissociates, delivering the inner double-layered particle (DLP) into the cytosol. DLP structures determined by X-ray crystallography and electron cryomicroscopy (cryoEM) show that the RNA coils uniformly into the particle interior, avoiding a "fivefold hub" of more structured density projecting inward from the VP2 shell of the DLP along each of the twelve 5-fold axes. Analysis of the X-ray crystallographic electron density map suggested that principal contributors to the hub are the N-terminal arms of VP2, but reexamination of the cryoEM map has shown that many features come from a molecule of VP1, randomly occupying five equivalent and partly overlapping positions. We confirm here that the electron density in the X-ray map leads to the same conclusion, and we describe the functional implications of the orientation and position of the polymerase. The exit channel for the nascent transcript directs the nascent transcript toward an opening along the 5-fold axis. The template strand enters from within the particle, and the dsRNA product of the initial replication step exits in a direction tangential to the inner surface of the VP2 shell, allowing it to coil optimally within the DLP. The polymerases of reoviruses appear to have similar positions and functional orientations.

The effects of smoking on estradiol metabolism

Smoking remains a major health problem especially among women and it influences estrogen metabolism and the risk for multiple estrogen sensitive outcomes. Many indirect effects of smoking exist through the ability of the by-products to modify a variety of drugs, enzymes, and hormones. The results of several in vitro studies have shown that constituents of cigarette smoke have significant effects on production and metabolism of estrogens. In some cases, such as osteoporosis and endometrial cancer, smoking appears to attenuate the effects of estrogen. However, for other outcomes such as breast cancer, venous thromboembolic events (VTE), and coronary heart disease (CHD), the relationship between smoking and estrogen exposure is less defined. Based on the preponderance of evidence, smokers are likely to require higher doses of hormone replacement therapy (HRT) to achieve comparable clinical effect to that observed in nonsmokers. However, uptitrating the dose of HRT in smokers to achieve a desired systemic level or clinical response may simultaneously increase risk for adverse effects that are primarily driven by hepatic rather than systemic exposure. The healthy benefits from smoking cessation should be expressed to women who choose to use HRT, and every effort should be made to encourage them to stop smoking so that they can be effectively treated with the lowest possible dose of HRT.

Orosensory factors in the ingestion of corn oil/sucrose mixtures by the rat

The experiments reported here were designed to study the orosensory factors contributing to the ingestion of sucrose/corn oil mixtures. When a flavor aversion was conditioned to the sucrose/corn oil mixture, the subsequent aversion to the mixture strongly generalized to the corn oil but very little to the sucrose. Rats conditioned with corn oil show a more profound aversion to the sucrose/corn oil mixture than rats conditioned with sucrose, indicating that the salient feature of the sucrose/corn oil mixture is the oil. Aversion to the sucrose/corn oil mixture does not generalize to a sucrose/mineral oil mixture, giving evidence that the textural aspects of the oil do not play a major role in its perception. This flavor aversion to the mixture is further illustrated in very short-term tests where postingestive factors are minimized, indicating a role for the gustatory system in the detection of the sucrose/corn oil mixture. Preliminary experiments are reported where conditioning tests were run with mixtures of sucrose and linoleic acid, one of the fatty acids that is possibly derived from a breakdown of the corn oil in the oral cavity by lingual lipase from von Ebner's Gland.

Brown's syndrome. An unusual manifestation of rheumatoid arthritis

Two patients presented with an ocular complication of rheumatoid arthritis that was extraocular in location. Clinical manifestations include vertical diplopia, an intermittent nature, a clicking sensation, and apparent inferior oblique palsy. A stenosing tenovaginitis of the superior oblique tendon and its sheath is the probable underlying pathologic mechanism.

Identification, evaluation, therapy, and follow-up for children with vocal nodules in a public school setting

This paper describes procedures used by speech and otorhinolaryngology specialists in the Independent School District of Carrollton and Farmers Branch, Texas, to identify, evaluate, treat, and follow up children with voice disorders and presents some initial findings resulting from the use of these procedures. In the identification process, 34 children were found to have vocal nodules, of which 31 children received treatment and underwent appropriate follow-up. After two months of voice therapy, 21 (68%) of the children exhibited reduced nodule size and seven (23%) exhibited normal larynges. Following six months of therapy, 26 (84%) children exhibited reduced nodule size, and 20 (65%) had normal larynges.