The tactile receptive fields of freely moving Caenorhabditis elegans nematodes.

Sensory neurons embedded in skin are responsible for the sense of touch. In humans and other mammals, touch sensation depends on thousands of diverse somatosensory neurons. By contrast, Caenorhabditis elegans nematodes have six gentle touch receptor neurons linked to simple behaviors. The classical touch assay uses an eyebrow hair to stimulate freely moving C. elegans, evoking evasive behavioral responses. This assay has led to the discovery of genes required for touch sensation, but does not provide control over stimulus strength or position. Here, we present an integrated system for performing automated, quantitative touch assays that circumvents these limitations and incorporates automated measurements of behavioral responses. The Highly Automated Worm Kicker (HAWK) unites a microfabricated silicon force sensor holding a glass bead forming the contact surface and video analysis with real-time force and position control. Using this system, we stimulated animals along the anterior-posterior axis and compared responses in wild-type and spc-1(dn) transgenic animals, which have a touch defect due to expression of a dominant-negative α-spectrin protein fragment. As expected from prior studies, delivering large stimuli anterior and posterior to the mid-point of the body evoked a reversal and a speed-up, respectively. The probability of evoking a response of either kind depended on stimulus strength and location; once initiated, the magnitude and quality of both reversal and speed-up behavioral responses were uncorrelated with stimulus location, strength, or the absence or presence of the spc-1(dn) transgene. Wild-type animals failed to respond when the stimulus was applied near the mid-point. These results show that stimulus strength and location govern the activation of a characteristic motor program and that the C. elegans body surface consists of two receptive fields separated by a gap.

Rise Time Reduction of Thermal Actuators Operated in Air and Water through Optimized Pre-Shaped Open-Loop Driving.

Electrothermal actuators have many advantages compared to other actuators used in Micro-Electro-Mechanical Systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10-90% rise time of 85 µs in air and 234 µs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10-90% rise time from 85 µs to 3 µs in air and from 234 µs to 5 µs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

The impact of the Affordable Care Act on health education: perceptions of leading health educators.

The health care system in the United States is being overhauled by major legislation, the Patient Protection and Affordable Care Act (ACA). This study's goal was to provide insight into the perceived impact and changes that could occur within the health education profession as a result of this health care reform legislation. Seven leaders of the health education profession participated in this qualitative research study. Six semistructured, exploratory interviews were conducted, and one participant provided written responses to the interview questions. A thematic analysis of the content of the interviews yielded five themes: (a) a fragmented sick-care system, (b) ACA becomes law: the participants' reactions, (c) ACA becomes law: the profession's reactions, (d) impact on the profession, and (e) health education in 2020. This article describes the fourth theme, the impact of the ACA on the health education profession. Leaders of the health education profession believed that the ACA creates a more favorable environment for health education practice. The positive elements of this legislation, however, will need to be protected, strengthened, and verified, through the work of health education professionals. As more mandates within the law are enacted over time, the impact on the profession, more than likely, will shift.

Planar patterned stretchable electrode arrays based on flexible printed circuits.

For stretchable electronics to achieve broad industrial application, they must be reliable to manufacture and must perform robustly while undergoing large deformations. We present a new strategy for creating planar stretchable electronics and demonstrate one such device, a stretchable microelectrode array based on flex circuit technology. Stretchability is achieved through novel, rationally designed perforations that provide islands of low strain and continuous low-strain pathways for conductive traces. This approach enables the device to maintain constant electrical properties and planarity while undergoing applied strains up to 15%. Materials selection is not limited to polyimide composite devices and can potentially be implemented with either soft or hard substrates and can incorporate standard metals or new nano-engineered conductors. By using standard flex circuit technology, our planar microelectrode device achieved constant resistances for strains up to 20% with less than a 4% resistance offset over 120,000 cycles at 10% strain.

Integrated strain array for cellular mechanobiology studies.

We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane, and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblast cells on the device for 6 hours. At higher strains, cells and actin stress fibers realign with a circumferential preference.

Artificial dirt: microfluidic substrates for nematode neurobiology and behavior.

With a nervous system of only 302 neurons, the free-living nematode Caenorhabditis elegans is a powerful experimental organism for neurobiology. However, the laboratory substrate commonly used in C. elegans research, a planar agarose surface, fails to reflect the complexity of this organism's natural environment, complicates stimulus delivery, and is incompatible with high-resolution optophysiology experiments. Here we present a new class of microfluidic devices for C. elegans neurobiology and behavior: agarose-free, micron-scale chambers and channels that allow the animals to crawl as they would on agarose. One such device mimics a moist soil matrix and facilitates rapid delivery of fluid-borne stimuli. A second device consists of sinusoidal channels that can be used to regulate the waveform and trajectory of crawling worms. Both devices are thin and transparent, rendering them compatible with high-resolution microscope objectives for neuronal imaging and optical recording. Together, the new devices are likely to accelerate studies of the neuronal basis of behavior in C. elegans.

Is abstinence education theory based? The underlying logic of abstinence education programs in Texas.

Authors examined the logic (or the implicit theory) underlying 16 abstinence-only-until-marriage programs in Texas (50% of all programs funded under the federal welfare reform legislation during 2001 and 2002). Defined as a set of propositions regarding the relationship between program activities and their intended outcomes, program staff's implicit theories were summarized and compared to (a) data from studies on adolescent sexual behavior, (b) a theory-based model of youth abstinent behavior, and (c) preliminary findings from the national evaluation of Title V programs. Authors interviewed 62 program directors and instructors and employed selected principles of grounded theory to analyze interview data. Findings indicated that abstinence education staff could clearly articulate the logic guiding program activity choices. Comparisons between interview data and a theory-based model of adolescent sexual behavior revealed striking similarities. Implications of these findings for conceptualizing and evaluating abstinence-only-until-marriage (or similar) programs are examined.

A review of 21 curricula for abstinence-only-until-marriage programs.

The authors reviewed the content, methods, and overall quality of 21 curricula used in abstinence-only-until-marriage programs. Only materials designed for use in middle school grades (fifth to eighth) or with middle school-aged audiences (9-13 years of age), which presented the abstinence message in at least 40% of their content, were included. A rating instrument adapted from 2 sets of education guidelines structured the assessment of each curriculum. Four experienced teachers rated each curriculum. Curricula exhibited considerable variability in overall quality ratings. While on average, materials scored a 3.33 on a 1-to-5 scale (1 = Unacceptable; 5 = Excellent), 12 curricula received summative scores above the average, with 4 scoring 4.0 or higher. Eight curricula, however, received a below-average rating. While abstinence materials vary considerably in terms of overall quality, the values and world views underlying this sample of curricula were clear and consistent: those who develop abstinence education curricula value nonsexual antecedents of sexual behavior such as skills (goal setting, decision making, and assertiveness), ideals (fidelity, friendships), and psychological factors such as self-esteem.

Defining abstinence: views of directors, instructors, and participants in abstinence-only-until-marriage programs in Texas.

This study examined how program directors, instructors, and participant youth from a sample of federally funded abstinence-only-until-marriage education programs in Texas define the term "abstinence" and its object (from what one abstains). A sample of eight programs, from the 32 federally funded programs in the state (funded in fiscal year 2000-2001), were selected for indepth case studies. Interviews were conducted with 29 program staff (10 directors and 19 instructors). Six focus group sessions were held with youth participating in the programs. Interview and focus group transcripts were analyzed qualitatively, with salient themes being coded and counted. Results are presented in terms of frequency of mention of each theme/code. Most respondents (80% of program directors, 89% of instructors, 83% of focus groups) provided definitions of abstinence containing both positive and negative elements. Positive-patterned definitions emphasized specific attitudes and behaviors that must be internalized by youth (Internal Management; Values/Attitudes Incorporation; Abstinence as an Option; Investment in the Future). Negative definitions stressed restraint and avoidance, and focused on the objects of abstinence (Sexual/Vaginal Intercourse; Oral Sex; Anal Sex; Pre-Coital Behaviors; Behaviors with Purpose of Sexual Arousal; Non-Sexual Behaviors). Each element was mentioned by at least 26% of program staff and in at least 17% of youth focus groups. Results indicated substantial variability in how the term "abstinence" is defined. Such variability has implications for development of abstinence education programs, as well as for implementation of valid, equitable, and useful evaluations.

Phase II trial of 5-fluorouracil plus eniluracil in patients with advanced pancreatic cancer: a Southwest Oncology Group study.

BACKGROUND: Eniluracil is a potent, irreversible inactivator of dihydropyrimidine dehydrogenase, the major catabolic enzyme for 5-fluorouracil (5-FU). Pretreatment with eniluracil significantly increases plasma half-life, plasma concentration and oral bioavailability of 5-FU. This multicenter phase II trial was designed to estimate the 6-month survival rate in patients with metastatic adenocarcinoma of the pancreas treated with 5-FU and eniluracil. PATIENTS AND METHODS: One hundred and sixteen patients (61 with no prior chemotherapy and 55 with prior chemotherapy) were registered for treatment with eniluracil 50 mg (total dose) p.o. on days 1-7 and 5-FU 20 mg/m(2)/day p.o. on days 2-6 of a 28-day treatment cycle. RESULTS: In 106 patients evaluable for survival, the 6-month survival rate was 34% [95% confidence interval (CI) 22% to 47%, median survival 3.6 months] for patients who had not been treated previously with chemotherapy and 29% (95% CI 16% to 42%, median survival 3.4 months) for those who had received prior chemotherapy. For those patients with measurable disease, the confirmed response rates were 8% and 2%, respectively. The most common grade 3-4 toxicities were neutropenia (29% of patients) and diarrhea (12% of patients). Overall, 69% of patients experienced a grade 3 or worse adverse event during treatment. CONCLUSIONS: These results suggest that the combination of a 7-day course of eniluracil and a 5-day course of oral 5-FU has limited activity in patients with advanced pancreatic cancer, and is associated with a high frequency of clinically significant adverse events.

Changes in the tissue and plasma superoxide dismutase (SOD) levels in a burned rat model.

To examine whether thermal injury alters the superoxide dismutase (SOD) concentrations in various types of tissue or plasma, we studied the plasma and tissue Mn- and Cu/Zn-SOD levels in a rodent burn model. The animals were resuscitated with saline (50 mg/kg, i.p.) immediately following thermal injury and thereafter were sacrificed at either 6 or 24 hours post-burn. The Mn- and Cu/Zn-SOD levels were measured using an enzyme-linked immunosorbent assay (ELISA). The plasma Mn- and Cu/Zn-SOD concentrations significantly increased 6 hours after the injury and positively correlated with the burn size. The kidney Mn-SOD concentrations were significantly higher 24 hours after the injury in the animals with 30% burns than in those with either sham or 50% burn injuries. The lung Cu/Zn-SOD concentrations were also significantly higher 6 hours after the injury in animals with 30% burns than in the other two types above. These findings suggest that the changes in the SOD concentrations after burn injury vary according to the type of SOD and also the type of tissue. As a result, the SOD concentrations may play some role in the early response to thermal trauma.

Appendicitis: why so complicated? Analysis of 5755 consecutive appendectomies.

A perceived high rate of complicated (gangrenous or perforated) appendicitis, despite advances in laboratory and radiographic diagnostic modalities, prompted a review of our experience with appendicitis followed by a prospective analysis that examined the time course from presentation to definitive treatment in 218 consecutive patients. In 5755 appendectomies, our overall rate of complicated appendicitis was 32 per cent; higher in males, in the young, and in the elderly; and relatively stable over each year reviewed. Prospectively, we determined that of the various time intervals, the time from the onset of symptoms to first seeking medical attention is the only significant predictor of complicated appendicitis (39.8 vs 16.5 hours for acute appendicitis). On the other hand, the time from surgical evaluation to operative intervention was significantly shorter for complicated appendicitis (3.8 vs 4.7 hours for acute appendicitis). The high rate of complicated appendicitis with its subsequent sequelae of increased morbidity and resource expenditure is primarily the direct result of patient delay in seeking medical attention and not the result of diagnostic dilemma or surgical delay. Public education, specifically targeting those groups at risk, may provide a substantial and significant solution to the complicated appendix.

Accelerated healing with a mesh autograft/allodermal composite skin graft treated with silver nylon dressings with and without direct current in rats.

PURPOSE: Evaluation of the healing and persistence of a meshed composite skin graft applied without immunosuppression. METHODS: The contraction of wounds grafted with 9:1 split-thickness autograft/1.5:1 allodermal mesh composite skin grafts (auto/allo MCSGs) was investigated. No immunosuppressive agent was applied. Male ACI rats and female Lewis rats reciprocally served as allodermis graft donors and recipients. Autograft/dermal autograft and allograft/dermal allograft MCSGs were the controls. RESULTS: AT 3 months after grafting, when epithelized auto/allo MCSG wounds were measured by computerized morphometric analysis, the silver nylon (SN) dressing group displayed less contraction than the Vaseline (petroleum jelly) dressing group (p < 0.003), and direct current treatment (SNDC) was more effective than SN (p < 0.005). The histologic structures of the hair follicles appear to confine the rejection process to the allogeneic follicles of the graft. The focal nature of the rejection process and the relatively low antigenicity of the dermal matrix allowed the survival of the allodermis layer. Although direct current significantly enhanced MCSG healing, SN and SNDC were not the immunosuppressive agents that were confirmed. CONCLUSION: This type of MCSG can heal without immunosuppressive treatment.

Half-life of blood carboxyhemoglobin after short-term and long-term exposure to carbon monoxide.

BACKGROUND: In models of smoke inhalation injury and carbon monoxide poisoning blood carboxy-hemoglobin (COHb) levels decrease faster than predicted by the generally recognized half-life of COHb. We studied the effects of duration of exposure to carbon monoxide (CO) on the subsequent CO elimination. METHODS: Each of four sheep were insufflated with CO gas mixtures either for a few minutes (short-term exposure) or for several hours (long-term exposure), then ventilated with air for 3 hours. Serial COHb concentrations were analyzed by using a two-compartment, single central outlet mathematical model. RESULTS: Short-term exposures exhibited biphasic decreases of COHb concentration compatible with a two-compartment model; an initial rapid decrease (half-life 5.7 +/- 1.4 minutes) was followed by a slower phase (103 +/- 20.5 minutes). Long-term exposures exhibited almost monophasic decreases, which were nevertheless compatible with the model (half-life, 21.5 +/- 2.1 and 118 +/- 11.2 minutes). CONCLUSION: This study demonstrated different patterns of CO elimination curve, which suggests distribution of CO to two compartments having different rates of equilibration.

Blunt splenic injuries: dedicated trauma surgeons can achieve a high rate of nonoperative success in patients of all ages.

BACKGROUND: Selective nonoperative management (NOM) of blunt splenic injuries is becoming a more prevalent practice. Inclusion criteria for NOM, which have been a source of controversy, continue to evolve. Age > or = 55 years has been proposed as a predictor for failure of and even a contraindication to NOM of blunt splenic trauma. Additionally, the high rate of NOM in children (up to 79%) has been attributed to their management by pediatric surgeons. We evaluated our experience with NOM of blunt splenic injury with special attention to these age groups. METHODS: By using our trauma registry, all patients with blunt splenic injuries (documented by computed tomography, operative findings, or both) cared for over a 36-month period, at a single American College of Surgeons verified Level I trauma center were reviewed. Detailed chart reviews were performed to examine admission demographics, laboratory data, radiologic findings, outcome measures, and patient management strategy. All patients were managed by nonpediatric trauma surgeons. We then compared our adult data with that in the recent literature and our pediatric data with that of the National Pediatric Trauma Registry over the same time period. RESULTS: We identified 251 consecutive patients with blunt splenic injuries. Eighteen patients who expired in the immediate postinjury period were excluded from statistical evaluation. No deaths occurred as a result of splenic injury. Of the remaining 233 patients, 73 patients (31%) required early celiotomy, 160 patients (69%) were selected for NOM, with 151 patients (94%) being successfully managed without operation. Blunt splenic injury occurred in 23 patients age 55 years or older. Eighteen patients (78%) were selected for NOM and 17 patients (94%) were successfully treated without operation. Blunt splenic injury occurred in 35 patients less than 16 years of age. Thirty-two patients (91%) were selected for NOM. Thirty-one patients (89% of all pediatric patients) were successfully treated without operation. CONCLUSION: Age > or = 55 years is not a contraindication to nonoperative management of blunt splenic injuries. Children with blunt splenic injuries can be successfully managed nonoperatively by nonpediatric trauma surgeons.

Effects of heme proteins on nitric oxide levels and cell viability in isolated PMNs: a mechanism of toxicity.

Isolated human PMNs served as a model to determine oxyhemoglobin (oxyHb) binding and the effects of oxymyoglobin (oxyMb) or oxyHb on production of both nitric oxide (NO*) and superoxide (O2*-) and the resulting cytotoxicity. Physiologically relevant concentrations of NO* and H2O2 oxidized, to a similar extent, 2,7-dichlorodihydrofluorescein (DCFH) loaded into polymorphonuclear neutrophils (PMNs). Activation of PMNs with phorbol 12-myristate 13-acetate (PMA) markedly increased the internalization of extracellular oxyHb (10-250 microg/mL). OxyMb (10-300 microg/mL) or oxyHb (30-300 microg/mL) enhanced DCFH oxidation by a concentration-dependent mechanism in unstimulated, lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-alpha)-, and PMA-stimulated PMNs. This increased DCFH oxidation was eliminated by NO* synthase inhibitors, glutathione and ascorbate, and was reduced by albumin. Nitrite accumulation in PMN filtrates mirrored NO*-induced DCF fluorescence. OxyMb-induced increases in NO* levels paralleled alterations in DNA and cell membrane damage and ATP levels in PMNs and co-cultured lymphocytes, and were attenuated by NO* synthase inhibitors. OxyMb eliminated extracellular O2*- at protein concentrations 100- to 1000-fold above those of superoxide dismutase. These results suggest that heme proteins bind and internalize into PMNs and increase NO*-induced damage in neighboring cells by inhibiting O2*(-)-scavenging of NO*. We propose a mechanism whereby heme protein-induced NO* levels may contribute to immunosuppression and increased infection rates associated with transfusions and cellular damage during inflammation.