An overview of FDA medical device regulation as it relates to deep brain stimulation devices.

The United States Food and Drug Administration (FDA) is charged with assuring the safety and effectiveness of a variety of medical products and the FDA's Center for Devices and Radiological Health is responsible for premarket and postmarket regulation of medical devices. In this paper, we review--from device classification and clinical studies to the final marketing application--FDA's premarket requirements and postmarket requirements as they relate to deep brain stimulation devices.     

The pancreatic cancer proteome - recent advances and future promise

Of the common cancers, pancreatic ductal adenocarcinoma is one of the most lethal. The cancer's aggressive biology, leading to rapid dissemination, combined with a lack of clearly recognisable symptoms means that for many patients, the disease is at an advanced stage when diagnosed. The prognosis is consequently very poor, with as few as 3-5% of patients surviving 5?years. Recently, proteomic technologies have been employed in an effort to identify protein biomarkers, therapeutic targets and disease response markers for pancreatic cancer. Research has primarily relied upon pancreatic tissue samples, and body fluids such as pancreatic juice and blood serum. In this article, we will highlight the current proteomic techniques, qualitative and quantitative, employed in the field of pancreatic cancer research. We will review both the progress made and the challenges ahead, in elaborating the biology of pancreatic cancer and identifying novel biomarkers.     

Deformation of concrete and cement paste loaded at constant temperatures from 140 to 724°C

Constant temperature creep of unsealed pure cement paste, gravel and lightweight concretes obtained under constant uniaxial compressive load are reported for temperatures between 140°C and 724°C. The work suggests that it is possible, within certain limits, to uncouple the time, stress and temperature functions of constant high temperature creep, which can be represented mathematically by a simple multiple of the three functions. The time functions of all three mixes were best represented by a power law with an exponent slightly influenced by temperature. It is suggested that the temperature function may not be sufficiently described by the Arrhenius relation during first heating. The temperature function indicated a sharp increase in creep for gravel concrete above 350°C caused by break-up of the aggregate. However, the sharp increase in creep for both lightweight concrete and cement paste above 600°C is seated in the cement paste and appears to be a function of “current” temperature. A rheological criterion therefore limits the structural usefulness of Portland cement concretes to temperatures below 600°C. Similarities in constant high temperature creep behaviour with other materials have been noted.     

Electrodeposition of copper into high aspect ratio PCB micro-via using megasonic agitation

This paper presents the use of micro-particle imaging velocimetry (micro-PIV) to analyse fluid flow and hence ion replenishment in PCB micro-via during the electroplating process. The cross section of a PCB via is fabricated in PMMA to allow optical access to the sample. Fluid flow within two 1:1 aspect ratio blind micro-vias, one with straight side walls and the other with tapered side walls were compared. Flow is also analysed in a 1:1 aspect ratio through via. Flow rates measured using micro-PIV are used to validate simulated flow models. The results show that there are increased flow rates within the blind via with tapered side walls. This goes some way to explaining the improved electroplating results obtained in industry when tapered vias are used. Initial experimental results using megasonic streaming to remove bubbles from blind micro-via and promote ion transportation within high aspect ratio PCB micro-via to enhance electrodeposition are also reported.     

Menstrual cycle, beta-endorphins, and pain sensitivity in premenstrual dysphoric disorder.

This study examined pain sensitivity and pain modularity mechanisms (e.g., beta-endorphin levels, blood pressure) in women with premenstrual dysphoric disorder (PMDD; n=27) and healthy controls (n=27) during the follicular and luteal phases of the menstrual cycle. Physiological measures were taken during rest and ischemic pain testing. In both cycle phases, PMDD women (a) displayed lower resting cortisol and beta-endorphin levels and (b) exhibited shorter pain threshold and tolerance times and greater pain unpleasantness ratings during pain. PMDD women also reported greater pain unpleasantness and intensity and had lower beta-endorphin levels in their luteal phase and tended to display higher blood pressure levels at rest and during pain testing. Results suggest that endogenous opioids may be pathophysiologically relevant to PMDD and that the hypothalamic-pituitary-gonadal axis may modulate pain sensitivity in PMDD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Another within-groups versus between-groups confusion?

Comments on J. M. Stoppard's (see record 1989-29654-001) discussion of the adequacy of cognitive/behavioral theories for understanding depression in women. Stoppard's claim that such theories' utility does not extend beyond the alleviation of a current episode is refuted. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PEDB: the Prostate Expression Database

Naloxone is generally considered to be a pure antagonist, but it may produce several behavioral effects, such as hyperalgesia or stimulation of respiration. We studied the effect of naloxone on gastric emptying and gastrointestinal transit in rats. Six to eight Wistar rats (200-250 g) were used for each experiment. Either saline or naloxone (0.01-10 mg/kg) was injected intraperitoneally at 0 min. At 30 min, radiolabeled saline or milk 1 mL was infused into the stomach. At 60 min, gastric emptying and gastrointestinal transit were calculated by measuring the radioactivity in the gastrointestinal tract. Naloxone significantly inhibited gastric emptying of saline (P = 0.002) and of milk (P < 0.05), but not the gastrointestinal transit of either (P > 0.05). Gastric emptying of saline showed a significant peak (P < 0.05) in the dose-response curve at 0.7 mg/kg. Therefore, naloxone significantly inhibits gastric emptying of saline and milk, but not the gastrointestinal transit of either. IMPLICATIONS: Although naloxone is generally considered to be a pure opioid receptor antagonist, it delays gastric emptying of saline or milk, as does morphine in the rat. However, it is uncertain from our results whether naloxone inhibited gastric emptying by antagonizing the effects of endogenous opioids.     

Major depression: A comparison of the routes to prevention.

Used data from various studies conducted in North America and Europe to (a) compare with population statistics and epidemiological data for Calgary, Alberta and (b) compare research routes to preventing major depression in women. Since preventing major depression by intervening when people are in specific crisis situations appears to be a promising approach, 5 crises that may occur in the lives of women are considered: mastectomy, rape, kidney failure, bereavement, and marriage breakdown. Data indicate that while crisis intervention is promising, the probability of major depression occurring after each specific crisis must be examined carefully. In some instances (e.g., marriage breakdown), although the crisis may appear to be a contributing cause of major depression, the population at risk may not be readily accessible. It is proposed that biological research is more likely than social research to provide a cumulative and stable body of evidence and to identify variables that are more readily modifiable. (French abstract) (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)