Electromechanical and elastic probing of bacteria in a cell culture medium.

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of bacteria of different types in pure water. Here, the BEPFM method is performed for the first time on physiologically relevant electrolyte media, such as Dulbecco's phosphate-buffered saline (DPBS) and Dulbecco's modified Eagle's medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria in DPBS are demonstrated. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media.

Functional recognition imaging using artificial neural networks: applications to rapid cellular identification via broadband electromechanical response.

Functional recognition imaging in scanning probe microscopy (SPM) using artificial neural network identification is demonstrated. This approach utilizes statistical analysis of complex SPM responses at a single spatial location to identify the target behavior, which is reminiscent of associative thinking in the human brain, obviating the need for analytical models. We demonstrate, as an example of recognition imaging, rapid identification of cellular organisms using the difference in electromechanical activity over a broad frequency range. Single-pixel identification of model Micrococcus lysodeikticus and Pseudomonas fluorescens bacteria is achieved, demonstrating the viability of the method.

Evidence for the aqueous absorption of gas from the eye following vitreoretinal surgery.

A standard part of vitrectomy surgery is to inject a bubble of gas into the eye, and an important question for the surgeon and patient alike is to know the volume of the bubble and how long it is likely to last. A related question of considerable importance is the mechanism by which it is absorbed. In this paper, we show how to use patients' measurements of the daily variation of their far points to calculate the changing volume of the bubble and hence the rate of gas absorption throughout the post-operative period. The results show that the rate of absorption contains a term in time squared, indicative of absorption through the exposed surface area of the aqueous fluid rather than via the exposed retina.

Compatibility of Medical-Grade Polymers with Dense CO(2).

This study reports the effect of exposure to liquid carbon dioxide on the mechanical properties of selected medical polymers. The tensile strengths and moduli of fourteen polymers are reported. Materials were exposed to liquid CO(2), or CO(2) + trace amounts of aqueous H(2)O(2), at 6.5 MPa and ambient temperature. Carbon dioxide uptake, swelling, and distortion were observed for the more amorphous polymers while polymers with higher crystallinity showed little effect from CO(2) exposure. Changes in tensile strength were not statistically significant for most plastics, and most indicated good tolerance to liquid CO(2). These results are relevant to evaluating the potential of liquid CO(2)-based sterilization technology.

Novel GPCR paradigms at the µ-opioid receptor.

UNLABELLED: Opioids, such as morphine, are the most clinically useful class of analgesic drugs for the treatment of acute and chronic pain. However, the use of opioids is greatly limited by the development of severe adverse side effects. Consequently, drug discovery efforts have been directed towards improving the therapeutic profile of opioid-based treatments. Opioid receptors are members of the family of GPCRs. As such, the recent GPCR paradigms of biased agonism and allosterism may provide novel avenues for more effective analgesics. Biased agonism (or functional selectivity) has been described for all the opioid receptor family members. Furthermore, the first allosteric modulators of opioid receptors have very recently been described. However, identification and quantification of biased agonism in a manner that is informative to medicinal chemists and drug discovery programmes still remains a challenge. In this review, we examine the progress, to date, towards identification and quantification of biased agonism and allosterism at the µ-opioid receptor in the context of its implications for the discovery of better and safer analgesics. LINKED ARTICLES: This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.

Effect of chest wall vibrations on pulmonary function in chronic bronchitis.

Manual chest wall vibration is one physiotherapeutic technique frequently employed in the management of respiratory disease. A clinical study was undertaken to examine the effects of manual chest wall vibrations on pulmonary function and arterial oxygen saturation in patients with chronic bronchitis. Twelve patients participated in a three-day experimental design where the factors of three different days and three different treatments were randomized and balanced. On one day, deep-breathing exercises were given; on another, deep-breathing exercises with vibrations; and on the remaining day, no treatment was given. Lung volumes were measured before and after each maneuver, and arterial oxygen saturation was monitored continuously. There was a significant decrease in the expiratory reserve volume (ERV) immediately following the deep-breathing exercises alone, which remained constant after the 15-minute rest period (p = 0.032). The remaining outcome parameters do not appear to be significantly affected. Chest wall vibrations do not decrease the ERV in patients with chronic bronchitis.

Bovine abortions associated with Bacteroides fragilis fetal infection.

Two Santa Gertrudis cattle from a herd of 105 aborted within a 24-hour period. Bacteroides fragilis was isolated from tissues of each aborted fetus. Histopathologic lesions included placentitis and bronchopneumonia in which gram-negative, rod-shaped organisms were visible. The diagnostic workup failed to reveal other causes of abortion. Anaerobes are rarely implicated in bovine abortions, and no other report was found that described abortion in cattle due to B. fragilis.

Mycobacterium paratuberculosis infection in two llamas.

Mycobacterium paratuberculosis was diagnosed in 2 llamas by bacteriologic culturing and DNA probe testing of fecal and intestinal specimens. Diarrhea and weight loss were observed in both animals. Lesions in the gastrointestinal tracts of the 2 llamas were similar to pathologic changes reported in cattle infected with M paratuberculosis.

Long-term trends in cancer mortality rates for West Virginia.

Using data on death certificates, we examined age-adjusted cancer mortality rates for West Virginia men and women from 1980-1994. The leading causes of cancer deaths among men in the state in 1994 were cancers of the lung, prostate, colon, and pancreas, and non-Hodgkin's lymphoma. Among West Virginia women in 1994, cancer deaths were most often due to cancers of the lung, breast, colon, pancreas, and ovary. Based on polynomial regression analyses, many of the leading cancer mortality rates significantly increased during 1980-1994. The most striking increase was a 76% rise in lung cancer mortality among West Virginia women. These mortality data underscore the continuing need for tobacco control and other cancer control practices. Even though barriers to medical care challenge the state's health care professionals, the burden of cancer in West Virginia can be reduced by prevention, early detection, and appropriate treatment.

Double-layer mediated electromechanical response of amyloid fibrils in liquid environment.

Harnessing electrical bias-induced mechanical motion on the nanometer and molecular scale is a critical step toward understanding the fundamental mechanisms of redox processes and implementation of molecular electromechanical machines. Probing these phenomena in biomolecular systems requires electromechanical measurements be performed in liquid environments. Here we demonstrate the use of band excitation piezoresponse force microscopy for probing electromechanical coupling in amyloid fibrils. The approaches for separating the elastic and electromechanical contributions based on functional fits and multivariate statistical analysis are presented. We demonstrate that in the bulk of the fibril the electromechanical response is dominated by double-layer effects (consistent with shear piezoelectricity of biomolecules), while a number of electromechanically active hot spots possibly related to structural defects are observed.

Quantifying the impact of prostate volumes, number of biopsy cores and 5alpha-reductase inhibitor therapy on the probability of prostate cancer detection using mathematical modeling.

PURPOSE: Previous studies demonstrated a negative correlation between prostate volume and biopsy yield. By decreasing prostate volume 5alpha-reductase inhibitors may enhance cancer detection, which may explain the greater detection of high grade tumors in the finasteride arm of the Prostate Cancer Prevention Trial. MATERIALS AND METHODS: A mathematical model was constructed to analyze the effects of prostate and tumor volumes, and biopsy core number on cancer detection. The effects of the volume reduction observed with finasteride in the Prostate Cancer Prevention Trial were also modeled, as was the potential reduction in tumor volume needed to explain the observed difference in prostate cancer detection. The model was also applied to the Reduction by Dutasteride of Prostate Cancer Events study. RESULTS: A higher number of biopsies are required to ensure a detection probability of 0.90 or greater in larger glands or with smaller tumors. In the Prostate Cancer Prevention Trial for a tumor volume of 1 cc a 17% increase in the detection rate in the finasteride arm would be predicted if there was no change in tumor volume, likewise the rate would be 11% to 17% for the dutasteride arm of the Reduction by Dutasteride of Prostate Cancer Events study. The calculated reduction in tumor volume needed to explain the difference in cancer detection between the finasteride and placebo arms of the Prostate Cancer Prevention Trial would be 51% to 66%. CONCLUSIONS: This model provides guidance on the optimal number of biopsy cores that accord with an earlier model. These findings also suggest that, if there were no reduction in tumor volume, 5alpha-reductase inhibitor therapy could lead to excess cancer detection, including high grade tumors.

A study of inhaled beclomethasone dipropionate therapy in asthma.

Fourteen patients with asthma have been followed in a long term clinical trial of the inhaled synthetic corticosteroid, beclomethasone dipropionate. All the patients were corticosteroid-dependent, with significant corticosteroid adverse effects. Twelve of the patients were able to stay on long term beclomethasone dipropionate therapy. Eight were able to discontinue use of systemic corticosteroids. There was a statistically significant reduction in the use of systemic corticosteroids (P<0.01) for the group when they were transferred to beclomethasone dipropionate. There was also an improvement of corticosteroid adverse effects in ten patients, but no significant change in their symptom scores. Several points of caution are stressed concerning long term clinical use of this promising drug.