An intra-cerebral drug delivery system for freely moving animals

Microinfusions of drugs directly into the central nervous system of awake animals represent a widely used means of unravelling brain functions related to behaviour. However, current approaches generally use tethered liquid infusion systems and a syringe pump to deliver drugs into the brain, which often interfere with behaviour. We address this shortfall with a miniaturised electronically-controlled drug delivery system (20 × 17.5 × 5 mm³) designed to be skull-mounted in rats. The device features a micropump connected to two 8-mm-long silicon microprobes with a cross section of 250 × 250 μm² and integrated fluid microchannels. Using an external electronic control unit, the device allows infusion of 16 metered doses (0.25 μL each, 8 per silicon shaft). Each dosage requires 3.375 Ws of electrical power making the device additionally compatible with state-of-the-art wireless headstages. A dosage precision of 0.25 ± 0.01 μL was determined in vitro before in vivo tests were carried out in awake rats. No passive leakage from the loaded devices into the brain could be detected using methylene blue dye. Finally, the device was used to investigate the effects of the NMDA-receptor antagonist 3-((R)-2-Carboxypiperazin-4-yl)-propyl-1-phosphonic acid, (R)-CPP, administered directly into the prefrontal cortex of rats during performance on a task to assess visual attention and impulsivity. In agreement with previous findings using conventional tethered infusion systems, acute (R)-CPP administration produced a marked increase in impulsivity.

Multi-cell type human liver microtissues for hepatotoxicity testing

Current 2-dimensional hepatic model systems often fail to predict chemically induced hepatotoxicity due to the loss of a hepatocyte-specific phenotype in culture. For more predictive in vitro models, hepatocytes have to be maintained in a 3-dimensional environment that allows for polarization and cell–cell contacts. Preferably, the model will reflect an in vivo-like multi-cell type environment necessary for liver-like responses. Here, we report the characterization of a multi-cell type microtissue model, generated from primary human hepatocytes and liver-derived non-parenchymal cells. Liver microtissues were stable and functional for 5 weeks in culture enabling, for example, long-term toxicity testing of acetaminophen and diclofenac. In addition, Kupffer cells were responsive to inflammatory stimuli such as LPS demonstrating the possibility to detect inflammation-mediated toxicity as exemplified by the drug trovafloxacin. Herewith, we present a novel 3D liver model for routine testing in 96-well format capable of reducing the risk of unwanted toxic effects in the clinic.

Osmotic micropumps for drug delivery

This paper reviews miniaturized drug delivery systems applying osmotic principles for pumping. Osmotic micropumps require no electrical energy and consequently enable drug delivery systems of smallest size for a broad field of new applications. In contrast to common tablets, these pumps provide constant (zero-order) drug release rates. This facilitates systems for long term use not limited by gastrointestinal transit time and first-pass metabolism. The review focuses on parenteral routes of administration targeting drug delivery either in a site-specific or systemic way. Osmotic pumps consist of three building blocks: osmotic agent, solvent, and drug. This is used to categorize pumps into (i) single compartment systems using water from body fluids as solvent and the drug itself as the osmotic agent, (ii) two compartment systems employing a separate osmotic agent, and (iii) multi-compartment architectures employing solvent, drug and osmotic agent separately. In parallel to the micropumps, relevant applications and therapies are discussed.

Long-term results of screening with magnetic resonance imaging in women with BRCA mutations

Background:

The addition of breast magnetic resonance imaging (MRI) to screening mammography for women with BRCA mutations significantly increases sensitivity, but there is little data on clinical outcomes. We report screening performance, cancer stage, distant recurrence rate, and breast cancer-specific mortality in our screening study.

Methods:

From 1997 to 2009, 496 women aged 25 to 65 years with a known BRCA1/2 mutation, of whom 380 had no previous cancer history, were enrolled in a prospective screening trial that included annual MRI and mammography.

Results:

In 1847 screening rounds, 57 cancers were identified (53 screen-detected, 1 interval, and 3 incidental at prophylactic mastectomy), of which 37 (65%) were invasive. Sensitivity of MRI vs mammography was 86% vs 19% over the entire study period (P<0.0001), but was 74% vs 35% from 1997 to 2002 (P=0.02) and 94% vs 9% from 2003 to 2009 (P<0.0001), respectively. The relative sensitivities of MRI and mammography did not differ by mutation, age, or invasive vs non-invasive disease. Of the incident cancers, 97% were Stage 0 or 1. Of 28 previously unaffected women diagnosed with invasive cancer, 1 BRCA1 mutation carrier died following relapse of a 3 cm, node-positive breast cancer diagnosed on her first screen at age 48 (annual breast cancer mortality rate=0.5%). Three patients died of other causes. None of the 24 survivors has had a distant recurrence at a median follow-up of 8.4 years since diagnosis.

Conclusion:

Magnetic resonance imaging surveillance of women with BRCA1/2 mutations will detect the majority of breast cancers at a very early stage. The absence of distant recurrences of incident cancers to date is encouraging. However, longer follow-up is needed to confirm the safety of breast surveillance.

Miniaturized osmotic pump for oromucosal drug delivery with external readout station

We report on a miniaturized, exchangeable drug delivery cartridge for Parkinson's Disease which is integrated in a partial removable prosthesis. An osmotic pumping principle uses saliva to release constantly a separately stored drug to the buccal mucosa, thus avoiding first pass metabolism and drug plasma level fluctuations. Therapeutic relevant information and fill level of the cartridge can be determined before and after usage with an external readout station. The selected material combinations of the cartridge fulfill both, functional and regulatory aspects as well as requirements for assembly and packaging, e.g. thermal fusion bonding, solvent bonding and capillary stop bonding. By using the cartridge, highly precise release rates over 97% of its storage capacity with a rate deviation of only 1.1% can be achieved.

Preferences for breast cancer prevention among BRCA mutation carriers

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Purpose: Breast cancer screening with MRI is a new option available to patients with BRCA 1/2 mutations. We analyzed preferences for this modality and 10 other breast cancer- related health states and preventive measures among women without cancer or known high risk and women with BRCA mutations. Methods: Following IRB approval, we administered a time trade-off questionnaire to mutation carriers and to women without breast cancer or known high risk. We used Kruskal-Wallis test to compare the two groups with respect to continuous variables, chi-square tests to compare proportions, and the Wilcoxon signed rank test for pairwise comparisons. We then developed logistic regression models to analyze the association of mutation carrier status and demographic factors with willingness to trade time for each of the 11 health states. Results: Two-hundred-four women (44 mutation carriers and 160 without breast cancer or known high risk) responded to the questionnaire. Both groups assigned the highest preference rating to mammography and the next-highest to MRI, but the differences in ratings were not statistically significant. Both groups assigned the lowest preference ratings to having a child with a mutation and the next lowest to ovarian cancer. In pairwise comparisons, both groups ranked oophorectomy higher than ovarian cancer (p <0.01), but mutation carriers did not rank prophylactic mastectomy significantly differently from breast cancer (p=0.38). In the logistic regression models, mutation carrier status was not a statistically significant predictor of willingness to trade time for any health state, but younger age, lower income, and nonwhite race/ethnicity were associated with willingness to trade time for certain health states. Conclusion: Our data indicate that MRI is as acceptable as mammography to respondents, and that the preferences of BRCA 1/2 mutation carriers are similar to those of other women. Age and other demographic factors may be more important than mutation status in determining preferences. The preference ratings of individuals should not be inferred from demographic characteristics or mutation status. However, such ratings can help to clarify the quality of life implications of clinical decision-making and health care policy regarding breast cancer prevention.

No significant financial relationships to disclose.

Is mammography adequate for screening BRCA mutation carriers with low breast density?

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Background: Several large observational studies have demonstrated that magnetic resonance imaging (MRI) is much more sensitive than M (sensitivity 71–96% vs. 28–43%) for screening women > age 25 at high risk for hereditary breast cancer. However, MRI is much more costly and less specific than M. The extent to which the low sensitivity of M in these studies is due to the greater average breast density of younger women is unknown. Accordingly, we sought to determine the sensitivity of M and MRI according to breast density for the detection of breast cancer in a screening study of BRCA mutation carriers. Methods: Breast density was measured on the screening mammogram of the contralateral breast for all women who developed in-situ or invasive breast cancer on study. Density was measured in 2 ways: qualitatively according to the four categories characterized by the BIRADS system: 1) mostly fatty, 2) scattered fibroglandular tissue, 3) heterogeneously dense, 4) extremely dense; and semi-quantitatively using computer-aided techniques with subsequent classification as: A) ≤10%, B) 11–25%, C) 26%-50%, or D) >50% density. Results: Between 11/97 and 06/05 a total of 39 cases (12 in-situ and 27 invasive) were found in 36 mutation carriers (19 BRCA1 and 17 BRCA2). Mean age of the women with cancer was 48 (range 34 to 64). Average semi-quantitative breast density for BRCA1 mutation carriers was 28% and for BRCA2 was 27%. Sensitivity of M vs. MRI for in-situ cases was 25% vs. 83%, and for invasive cases was 30% vs. 93%. Sensitivities for BRCA1 and BRCA2 mutation carriers were similar. For BIRADS 1 to 4 respectively M detected 1/3 (33%), 5/11 (45%), 4/22 (18%), and 1/3 (33%) of cases; and for density groups A to D respectively detected 2/6 (33%), 7/15 (47%), 1/11 (9%) and, 1/7 (14%). Conclusion: Although there was a trend towards decreasing mammographic sensitivity with increasing density, even among BRCA mutation carriers with low breast density mammography is an inadequate screening tool.

No significant financial relationships to disclose.

Microfluidics: an opportunity for trend-setting drug delivery

The past has demonstrated that when working with microfluidics only the following scenario is likely to lead to successful system development: a high level of component integration at an early development stage with an application-specific, simple (reliable) design, and a high interdisciplinary level of know-how over a broad range of technologies, pharmacology and medicine. The mere application of existing nonspecifically designed or outsourced microfluidic components is likely to fail because the system behaviour in the microworld is far different from that in the macroworld.

Evolution of reduced dispersal mortality and 'fat-tailed' dispersal kernels in autocorrelated landscapes

Models describing the evolution of dispersal strategies have mostly focused on the evolution of dispersal rates. Taking trees as a model for organisms with undirected, passive dispersal, we have developed an individual-based, spatially explicit simulation tool to investigate the evolution of the dispersal kernel, P(r), and its resulting cumulative seed-density distribution, D(r). Simulations were run on a variety of fractal landscapes differing in the fraction of suitable habitat and the spatial autocorrelation. Starting from a uniform D(r), evolution led to an increase in the fraction of seeds staying in the home cell, a reduction of the dispersal mortality (arrival in unsuitable habitat), and the evolution of 'fat-tailed' D(r) in autocorrelated landscapes and approximately uniform D(r) in random landscapes. The evolutionary process was characterized by long periods of stasis with a few bouts of rapid change in the dispersal rate.

Immunomodulatory action of G-CSF in a rat model of endotoxin-induced liver injury: an intravital microscopic analysis of Kupffer cell and leukocyte response

In contrast to the anticipation that in sepsis granulocyte colony-stimulating factor (G-CSF) would overactivate the nonspecific immune system by recruiting and priming leukocytes with consequent aggravation of inflammatory tissue lesions, recombinant (r) G-CSF pretreatment was protective in various experimental non-neutropenic models of inflammation. The mechanisms of protection, however, are not fully understood. Using intravital fluorescence microscopy, we show that rG-CSF enhances leukocyte endothelial cell interaction within the microvasculature of normal rat livers, whereas rG-CSF pretreatment of animals exposed to lipopolysaccharide (LPS) attenuates the LPS-induced leukocytic response, including stasis in sinusoids as well as rolling and adherence in postsinusoidal venules with subsequent tissue infiltration. Moreover, rG-CSF, which did not affect Kupffer cell activity in normal rat livers, reduced the immediate activation of Kupffer cells on LPS exposure, as indicated in vivo by the delayed adherence/phagocytosis of intra-arterially administered latex particles associated with attenuation of proinflammatory cytokine release (tumor necrosis factor alpha and interleukin-6). Finally, rG-CSF reduced LPS-induced nutritive perfusion failure and hepatocellular excretory dysfunction. This study provides evidence for a distinct, possibly tumor necrosis factor alpha-dependent modulation of LPS-induced cellular response within the liver by rG-CSF, thereby achieving protection against microcirculatory perfusion failure and hepatic dysfunction.

The influences of cognitive resources on adaptation and old age

In the Georgia Centenarian Study, cognitive resources were estimated by fluid and crystallized intelligence, acquisition and retrieval of new information, retrieval of familiar information, and problem-solving ability in community-dwelling and nondemented adults ranging from sixty to one hundred plus years of age. Five clusters of results were found: 1) cognitive performances were lower for the older cohorts; 2) when cognitive activities were dependent on everyday experiences, no age-related problem-solving decline was found; 3) physical health and mental health can significantly influence cognitive performances; 4) cognitive and personality factors can combine to account for a larger amount of adaptation variance than can be accounted for by either of the factors alone; and 5) individuals with a high level of intelligence and affect sustain their instrumental activities of daily living. Cognitive resources were an important contributor to successful adaptation for the oldest-old.

Differentiating opioids by their pupillary effects in the rat

Pupillary effects of several opioids were examined as part of a broader in vivo study of multiple opioid receptors in the rat. Agonist activity, stereospecificity, and naloxone sensitivity were determined by methadone (Me), ethylketocyclazocine (EK), and N-allylnormetazocine (SKF 10,047), selected for their purportedly predominant actions at mu, kappa, and sigma receptors, respectively. After an acute, subcutaneous injection of each drug, pupil area and fluctuations in pupil size were measured by means of an infrared video pupillometer on line with a microcomputer data processing and storage system. Despite differences in the magnitude of the response, each opioid tested produced an increase in pupil size which was stereospecific, independent of behavioral responses to the drugs and, for 1-Me and 1-SKF 10,047, dose-related. Other differences among the opioids were found in their ability to induce fluctuations (1-Me and 1-EK) and a pendular nystagmus (1-SKF 10,047 only), and in their sensitivity to naloxone. Although 1.0 mg/kg naloxone completely reversed 1-Me-induced mydriasis, 10 mg/kg was needed to reverse 1-EK, and this dose only partially antagonized 1-SKF 10,047. These characteristic patterns of pupillary responses to opioids in terms of agonist activities and naloxone sensitivities indicate that the different opioid receptor types subserve different functions with respect to pupillary control.