Myosin II Adjusts Motility Properties and Regulates Force Production Based on Motor Environment

Introduction

Myosin II has been investigated with optical trapping, but single motor-filament assay arrangements are not reflective of the complex cellular environment. To understand how myosin interactions propagate up in scale to accomplish system force generation, we devised a novel actomyosin ensemble optical trapping assay that reflects the hierarchy and compliancy of a physiological environment and is modular for interrogating force effectors.

Methods

Hierarchical actomyosin bundles were formed in vitro. Fluorescent template and cargo actin filaments (AF) were assembled in a flow cell and bundled by myosin. Beads were added in the presence of ATP to bind the cargo AF and activate myosin force generation to be measured by optical tweezers.

Results

Three force profiles resulted across a range of myosin concentrations: high force with a ramp-plateau, moderate force with sawtooth movement, and baseline. The three force profiles, as well as high force output, were recovered even at low solution concentration, suggesting that myosins self-optimize within AFs. Individual myosin steps were detected in the ensemble traces, indicating motors are taking one step at a time while others remain engaged in order to sustain productive force generation.

Conclusions

Motor communication and system compliancy are significant contributors to force output. Environmental conditions, motors taking individual steps to sustain force, the ability to backslip, and non-linear concentration dependence of force indicate that the actomyosin system contains a force-feedback mechanism that senses the local cytoskeletal environment and communicates to the individual motors whether to be in a high or low duty ratio mode.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00731-1.

Determination of vibrational band positions in the E-hook of β-tubulin

Raman spectral characterization of the β-TUBB2A E-hook hexapeptide, EGEDEA, is determined through experimental analysis combined with full geometry optimizations and corresponding harmonic vibrational frequency computations employing DFT methods. The hexapeptide is first broken down into di- and tetrapeptide fragments which are analyzed both quantum chemically and experimentally, and then combined to achieve an energetic minimum of the large EGEDEA hexapeptide. The Raman spectral characterization of EGEDEA band positions are then verified via the literature and comparison to the small fragment's similarly located band positions. The approach employed provides further evidence for the use of fragments as a helpful tool in characterization of the vibrational band positions of large peptides. STATEMENT OF SIGNIFICANCE: To investigate β-TUBB2A E-hook hexapeptide, a unique approach is employed whereby the hexapeptide is broken into fragments, EG, ED, EA, EGED, and EDEA and analyzed via experimental Raman spectroscopy of the crystalline solids. The experimentally observed vibrational band positions are compared to those computed using and scaled from DFT methods and Pople's 6-311+G(2df,2pd) basis set. The reported vibrational band positions are also confirmed by previously reported bands of similar peptides in the literature. This methodology facilitates differentiation between the behaviors of various side chains and their influence on the structure of the hexapeptide, providing insight into not only the nature of the peptide but also defining regions for potential protein and cytoplasmic interactions, without requiring excessive computing resources or overly-sensitive experimental methods.

Effect of an extreme flood event on solute transport and resilience of a mine water treatment system in a mineralised catchment

Extreme rainfall events are predicted to become more frequent with climate change and can have a major bearing on instream solute and pollutant transport in mineralised catchments. The Coledale Beck catchment in north-west England was subject to an extreme rainfall event in December 2015 that equated to a 1 in 200-year event. The catchment contains the UK's first passive metal mine water treatment system, and as such had been subject to intense monitoring of solute dynamics before and after commissioning. Due to this monitoring record, the site provides a unique opportunity to assess the effects of a major storm event on (1) catchment-scale solute transport, and (2) the resilience of the new and novel passive treatment system to extreme events. Monitoring suggests a modest decline in treatment efficiency over time that is not synchronous with the storm event and explained instead by changes in system hydraulic efficiency. There was no apparent flushing of the mine system during the event that could potentially have compromised treatment system performance. Analysis of metal transport in the catchment downstream of the mine suggests relatively subtle changes in instream chemistry with modest but statistically-significant reductions in zinc in the lower catchment irrespective of flow condition after the extreme event, but most parameters of interest show no significant change. Increased export of colloidal iron and aluminium is associated with major landslips in the mid-catchment after the storm and provide fresh sorption sites to attenuate dissolved zinc more rapidly in these locations, corroborated by laboratory experiments utilising site materials to investigate the attenuation/release of metals from stream and terrestrial sediments. The data are important as they show both the resilience of passive mine water treatment systems to extreme events and the importance of catchment-scale monitoring to ensure continued effectiveness of treatment initiatives after major perturbation.

0218 Biomathematical Modeling Predicts Fatigue Risk in General Surgery Residents

Introduction

Fatigue and its effects on performance have long been a concern in medicine. Evidence exists that current duty-hour restrictions for resident trainees have a limited impact on physician wellbeing and patient safety, prompting renewed efforts to address this threat. In this study, sleep patterns of general-surgery residents were used to optimize a biomathematical model of performance for use as a tool for fatigue risk management with residents.

Methods

General surgery residents based at a multi-hospital, general surgery residency program were approached for participation in this study. Enrolled residents wore actigraph devices for 8 weeks and completed subjective sleep assessments. Sleep data and shift schedules were then input into the Sleep, Activity, Fatigue and Task Effectiveness (SAFTE) Model to assess predicted cognitive performance. Performance was compared to an “effectiveness” level of 77 (equivalent to a blood-alcohol content of 0.05g/dL). Eight hours of sleep debt was considered “below reservoir criteria”.

Results

Sleep actigraphy data was collected from 22 general surgery residents. Modeling results showed that as shift lengths increased, effectiveness scores generally decreased, and the time spent below criterion (77) increased. Additionally, 11.13% of time on shift was below the effectiveness criterion and 42.7% of shifts included time spent below the reservoir criterion. Adjustments to the sleep prediction were made based on actual sleep, and performance predictions from actual sleep and the adjusted model were significantly correlated (p<.0001).

Conclusion

Despite adherence to national standards limiting work hours, current surgical resident sleep patterns and shift schedules create concerning levels of fatigue. This study illustrates how biomathematical fatigue models can predict resident physician sleep patterns and performance. Modeling represents a novel and important tool for medical educators seeking to create shift schedules that maintain physician preparedness and minimize fatigue risk.

Support

N/A

0184 Predicting Strategic Napping in Surgical Residents by Individual and Rotation Characteristics

Introduction

Strategic napping, or napping on-shift, is recommended to reduce fatigue in medical residents. The actual prevalence of strategic napping in relation to residents’ workload, schedule, or demographics is largely unquantified. This study objectively measured sleep patterns and work schedules in surgical residents working a variety of service lines over a two-month period in order to identify which resident and service line attributes predict on-shift napping.

Methods

Surgical residents from an academic surgery program in the Washington, DC area provided schedule information, completed the Epworth Sleepiness Scale (ESS), and wore sleep-tracking devices (Zulu Watch) continuously for 8 weeks. Multiple linear regression was performed to predict percent days with on-shift napping from resident demographics (age, gender, post graduate year (PGY), sleep characteristics (ESS, total sleep time (TST), sleep efficiency (SE)), schedule characteristics (shift start time, shift length, rotation length, percent days on-shift, percent night shifts), and service line characteristics (service line category, number of service lines worked).

Results

Twenty-two (n=22) residents completed the study, rotating through at least 1 of 5 different service line categories (Acute Non-Elective Surgery, Elective Surgery, Night Float, Surgical Intensive Care Unit, and Other). Residents slept an average of 6 hours within a 24-hour period (370±129 minutes) with normal SE (87.13%±7.55%). ESS scores indicated excessive daytime sleepiness (11.64±4.03). Ninety-five percent (n=21) of residents napped at least once while on shift. Residents napped on-shift approximately 32% of their working days and were most likely to nap when working between 2300-0500 hours. Earlier shift start times predicted less on-shift napping (B=-0.08,SE=0.04,β=-2.40,t=-2.09,p=0.05) while working more night shifts (B=1.55,SE=0.44,β=4.12,t=3.52,p=0.003) and shifts over 24 hours.

Conclusion

Residents take advantage of opportunities to nap on-shift, particularly when working at night. Despite naps, however, residents exhibit insufficient sleep with excessive daytime sleepiness, representing a safety risk to themselves and their patients.

Support

NA

Conceptual Tempo, Inhibition of Movement, and Acceleration of Movement in 4-, 7-, and 9-YR.-Old Children

The relationships among conceptual tempo, the ability to inhibit movement, and the ability to accelerate movement were studied in 4-, 7-, and 9-yr.-old boys and girls. Conceptual tempo was measured by Kagan's Matching Familiar Figures and motor inhibition and motor acceleration were measured by the Walk-a-Board, Reel-up, and Finger Tap tests. The ability to inhibit movement was correlated with the ability to accelerate movement and both were related to conceptual tempo for boys. For girls, movement acceleration and conceptual tempo were not related. The relationships were strongest for 4-yr.-olds and decreased as age increased.

Tropospheric Emissions: Monitoring of Pollution (TEMPO)

TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution (~2.1 km N/S×4.4 km E/W at 36.5°N, 100°W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide),water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the North American component of the global geostationary constellation of pollution monitoring together with the European Sentinel-4 (S4) and Korean Geostationary Environment Monitoring Spectrometer (GEMS) instruments.

Therapeutic effect of flax-based diets on fatty liver in aged laying hens

This study examined the ability of flax-based ingredients to attenuate nonalcoholic fatty liver disease ( NAFLD: ) in aged laying hens-a novel and more physiologically relevant model of human disease. Our results showed only hens supplemented with whole flaxseed ( WFX: ) reduced steatosis and hepatocellular ballooning. Serum AST was also reduced in hens provided WFX and defatted flaxseed meal ( DFM: ). Hepatic ω-3 PUFA enrichment was improved with supplementation of WFX, DFM, and flaxseed oil ( FXO: ). However, this effect was more evident in the WFX group. In contrast, transcript abundance of genes linked to NAFLD were predominantly modified with FXO supplementation. Taken together, our data indicate a potential synergistic relationship between the fatty acid and lignan content in flaxseed which attenuated the progression of NAFLD in aged laying hens. Although more research is necessary, these findings demonstrate the potential use of whole flaxseed for the treatment and prevention of NAFLD in humans.

Parental behavior correlates to baseline corticosterone of mates and offspring in nesting eastern bluebirds (Sialia sialis)

Raising nestlings in a biparental species involves a complex and dynamic interaction of physiology and behavior among a group of organisms. Parents may be predicted to vary their behaviors based not only upon their own state, but also in relation to the states of both offspring and the other parent. In this study we explore the relationships between parental feeding behaviors and family member condition in eastern bluebirds, with a special emphasis on baseline corticosterone, a hormone associated with energy mediation and stress. We found that the overall number of feeding trips made by both male and female parents were positively correlated to the corticosterone levels of nestlings. Maternal, but not paternal, baseline corticosterone levels were positively correlated to nestling baseline corticosterone levels. Additionally, adult males' feeding behavior was positively correlated to adult females' baseline corticosterone levels. These findings suggest a complex interplay between parental behavior and physiological state not only within a given organism, but also across organisms operating within a family unit. In addition, these results provide evidence that paternal and maternal efforts are influenced by related but distinct pressures, and that male and female parenting may be governed differentially even in species with relatively equitable biparental care.

Effects of exercise on S-IGA and URS in postmenopausal women

32 postmenopausal women were randomized to a 16-week home-based walking program or control group. Before and after the intervention, each subject completed a graded maximal treadmill test to establish VO(2)max and resting saliva was collected to determine levels of salivary immunoglobulin A. The 16-week walking program resulted in an increase in VO(2)max (+10.4%; p<0.01). Repeated measures ANOVA revealed a marked increase in the resting secretion rate of salivary immunoglobulin A (+37.4%; p<0.05) in the exercise group following training. Independent of study group, both before and after the intervention, the secretion rate of salivary immunoglobulin A ( - 32.3%) and saliva flow rate (- 29.3%) were reduced following acute maximal exercise (p<0.05). Weekly upper respiratory symptomatology logs revealed that the number of incidences of upper respiratory symptoms throughout the intervention period were the same and the duration per incidence (control: 5.3±1.5 days; exercise: 6.3±2.2 days) were similar between study groups. These findings in postmenopausal women support that the secretion rate of salivary immunoglobulin A and saliva flow rate are reduced immediately following maximal exercise. Moreover, a 16-week moderate intense walking program can increase the secretion of salivary immunoglobulin A without affecting upper respiratory symptomatology.

Soy protein isolate modified metabolic phenotype and hepatic Wnt signaling in obese Zucker rats

We have previously shown that soy protein isolate (SPI) with intact phytoestrogen content prevented obesity-related dysfunction. Recent data have suggested that soy ingredients may act as regulators of adipogenic programming in adipose tissue (AT) and liver. Thus, the current study was undertaken to determine whether the beneficial effects of SPI are linked to changes in adipogenic regulators, such as the Wnt signaling cascade. For this, lean (LZR) and obese Zucker (OZR) rats were provided isocaloric and isonitrogenous diets containing SPI, sodium caseinate, or dairy whey protein for 17 weeks. At termination, SPI increased body weight and total adiposity in rodents, which corresponded with an increase in both adipocyte size and number. Furthermore, markers of inflammation, hypercholesterolemia, and hepatic steatosis were all reduced in OZR rats provided SPI. Transcript abundance of several canonical and noncanonical Wnt signaling intermediates in liver, but not AT, was distinctly modified by SPI. Collectively, these data confirm the protective SPI attenuated obesity-related metabolic dysfunction conceivably through regulation of adipogenic programming, as evident by changes in AT morphology and hepatic Wnt signaling. Collectively, this study confirmed the potential utilization of soy protein and its bioactive ingredients for prevention and treatment of obesity-related comorbidities.

The c-Jun N-terminal kinase mediates the induction of oxidative stress and insulin resistance by palmitate and toll-like receptor 2 and 4 ligands in 3T3-L1 adipocytes

Saturated fatty acids (SFAs) are known to induce inflammation and insulin resistance in adipocytes through toll-like receptor-4 (Tlr4) signaling, but the mechanisms are not well delineated. Furthermore, the potential roles of Tlr2 and the c-Jun N-terminal kinase (JNK) in inflammation in adipocytes have not been investigated. We demonstrated that palmitate, lipopolysaccharide (LPS), and the toll-like receptor-2 (Tlr2) agonist, zymosan A (ZymA), induced insulin resistance in a time- and dose-dependent manner in 3T3-L1 adipocytes. Corresponding with the reduction of insulin sensitivity was an increased expression of IL-6, as well as activation of the proinflammatory transcription factors, nuclear factor kappa B, and activator protein-1. Reactive oxygen species (ROS) accumulation was also observed in palmitate and Tlr agonist treated adipocytes. The JNK inhibitor, SP600125, attenuated insulin resistance mediated by SFA and Tlr agonists, which corresponded with a diminished proinflammatory response and reduced ROS accumulation. Collectively, these results demonstrated Tlr2 involvement in adipocyte inflammation and therefore implicated the receptor as a potential target for SFA. Moreover, activation of JNK also appeared to be essential to Tlr2-, as well as Tlr4-induced insulin resistance and oxidative stress.

Adipocytes, myofibers, and cytokine biology: new horizons in the regulation of growth and body composition

Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Therefore, understanding the impact of stress and disease on muscle growth is essential to improving production efficiency. The adipocyte in particular seems to be well positioned as an interface between energy status and immune function, and may thus influence nutrient partitioning and growth through a combination of signals that influence fat metabolism, glucose uptake, and insulin sensitivity. Adipocytes and myofibers are active participants in the innate immune response, and as such, produce a number of metabolic regulators, including leptin, adiponectin, and proinflammatory cytokines. Specifically, adipocytes and muscle cells respond directly to bacterial lipopolysaccharide (LPS) by producing interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha). However, adipocytes are also the predominant source of the antiinflammatory hormone adiponectin, which regulates the nuclear factor kappa-B transcription factor. The ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally, and to reciprocally regulate metabolism peripherally.

Hippocampal vulnerability following traumatic brain injury: a potential role for neurotrophin-4/5 in pyramidal cell neuroprotection

Traumatic brain injury (TBI) causes selective hippocampal cell death, which is believed to be associated with cognitive impairment observed both in clinical and experimental settings. Although neurotrophin administration has been tested as a strategy to prevent cell death following TBI, the potential neuroprotective role of neurotrophin-4/5 (NT-4/5) in TBI remains unknown. We hypothesized that NT-4/5 would offer neuroprotection for selectively vulnerable hippocampal neurons following TBI. Measurements of NT-4/5 in rats subjected to lateral fluid percussion (LFP) TBI revealed two-threefold increases in the injured cortex and hippocampus in the acute period (1-3 days) following brain injury. Subsequently, the response of NT-4/5 knockout (NT-4/5(-/-)) mice to controlled-cortical impact TBI was investigated. NT-4/5(-/-) mice were more susceptible to selective pyramidal cell loss in Ahmon's corn (CA) subfields of the hippocampus following TBI, and showed impaired motor recovery when compared with their brain-injured wild-type controls (NT-4/5(wt)). Additionally, we show that acute, prolonged administration of recombinant NT-4/5 (5 microg/kg/day) prevented up to 50% of the hippocampal CA pyramidal cell death following LFP TBI in rats. These results suggest that post-traumatic increases in endogenous NT-4/5 may be part of an adaptive neuroprotective response in the injured brain, and that administration of this neurotrophic factor may be useful as a therapeutic strategy following TBI.

Heterokaryon formation and parasexual recombination between vegetatively incompatible lineages in a population of the chestnut blight fungus, Cryphonectria parasitica

Heterokaryosis was recently reported in the chestnut blight fungus, Cryphonectria parasitica, in which individuals contain nuclei that are isogenic except at the mating-type locus (MAT). MAT heterokaryons were found in several natural populations, including a putatively clonal population in West Salem, Wisconsin, providing an opportunity to address the question of how heterokaryons arise. We represented relationships among RFLP fingerprint haplotypes as networks in which loop formation is considered evidence of recombination. From 1990 to 1995, this population was clonal, as indicated by a simple haplotype network without loops, and the correlation of vegetative compatibility (vc) types and mating types with haplotype lineages. By 1999, we observed loops in the haplotype network involving isolates of two vc types (WS-2 and WS-3). Isolates with haplotypes in the loops were either MAT heterokaryons, carried the opposite mating type from other isolates of the same vc type, and/or had two alleles at two or more codominant SCAR (sequence-characterized amplified region) loci. Segregation of markers and recombination were evident among single-spore isolates from one heterokaryon; these single-spore isolates had novel fingerprint haplotypes, also within the loops. In contrast, vc type WS-1, which comprises 85% of the population, was represented by a simple network with no loops, indicating a clonal lineage varying only by mutation. Almost all isolates of WS-1 had the same mating type; the exceptions were five isolates that were MAT heterokaryons. These results are consistent with the hypothesis that heterokaryons formed between vegetatively incompatible individuals, and recombination occurred by a parasexual process.

Recurrent hepatocellular carcinoma after liver transplantation mimicking post-transplantation lymphoproliferative disorder

Approximately 5% of patients with end-stage cirrhosis undergoing orthotopic liver transplantation have occult hepatocellular carcinoma. Careful follow up is required to detect recurrent tumour, and knowledge of the patterns of recurrence may avoid diagnostic confusion with other malignancies, such as post-transplantation lymphoproliferative disorder. This case report illustrates an unusual presentation of recurrent hepatocellular carcinoma in a 56-year-old man presenting with a para-aortic soft tissue mass, thought clinically and radiologically to represent lymphoma or post-transplantation lymphoproliferative disorder. This case demonstrates that recurrent hepatocellular carcinoma can present late after transplantation as retroperitoneal lymphadenopathy, and should alert physicians and radiologists to be aware of the radiological appearances of recurrence and of the need for early biopsy to avoid diagnostic confusion with other malignancies.

Treatment options for post-transplant lymphoproliferative disorder and other Epstein-Barr virus-associated malignancies

Epstein-Barr virus (EBV) is associated with a range of malignancies that largely arise from a defect in EBV-specific cytotoxic T lymphocyte (CTL) immunity and function. Much work has focused on the reconstitution of CTL immunity to EBV in transplant patients, in whom immunosuppression modalities render them susceptible to post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of autologous CTLs is effective at both preventing and curing PTLD in solid organ transplant recipients and can produce a long-term memory response and protection against recurring disease. In this review, the benefits and restrictions of administering EBV-specific CTLs for the treatment of PTLD are discussed and compared with emerging therapies including the generation of allogeneic human leukocyte antigen-matched CTL banks and the anti-CD20 monoclonal antibody therapy, MabThera. Furthermore, studies involving other EBV-associated disorders have described the potential benefit of adoptive transfer of EBV-specific CTLs for Hodgkin's disease, nasopharyngeal carcinoma, chronic active EBV infection, and Burkitt's lymphoma. The challenges of tailor-making therapies for individual diseases and EBV antigen expression latencies are highlighted, in addition to considering vaccination strategies for optimal treatment.

Translabial sonography of vaginal fibroids: report of 2 cases and review of the literature

OBJECTIVE

To determine the role of translabial sonography in the diagnosis of vaginal fibroids.

METHODS

Two women with vaginal masses of undetermined origin were examined by various imaging procedures, including translabial sonography.

RESULTS

Initial examinations, which included transabdominal sonography, cystoscopy, and cystourethrography, yielded inconclusive findings. Translabial sonography, however, suggested isolated vaginal leiomyomas in both patients, and in both the diagnosis was confirmed histologically after surgery.

CONCLUSIONS

Translabial sonography should be considered as an adjunct to transabdominal and transvaginal sonography for patients with suspected vaginal fibroids.

Unlocking the secrets of cytotoxic granule proteins

Cytotoxic lymphocytes largely comprise CD8(+) cytotoxic T cells and natural killer cells and form the major defense of higher organisms against virus-infected and transformed cells. A key function of cytotoxic lymphocytes is to detect and eliminate potentially harmful cells by inducing them to undergo apoptosis. This is achieved through two principal pathways, both of which require direct but transient contact between the killer cell and its target. The first, involving ligation of TNF receptor-like molecules such as Fas/CD95 by their cognate ligands, results in mobilization of conventional, programmed cell-death pathways centered on activation of pro-apoptotic caspases. This review concentrates on the second pathway, in which the toxic contents of secretory vesicles of the cytotoxic lymphocyte are secreted toward the target cell, and some toxins penetrate into the target cell cytoplasm and nucleus. In addition to invoking a powerful stimulus to caspase activation, this "granule-exocytosis mechanism" provides a variety of additional strategies for overcoming inhibitors of the caspase cascade that may be elaborated by viruses. The key molecular players in this process are the pore-forming protein perforin and a family of granule-bound serine proteases or granzymes. The molecular functions of perforin and granzymes are under intense investigation in many laboratories including our own, and recent advances will be discussed. In addition, this review discusses the evidence pointing to the importance of perforin and granzyme function in pathophysiological situations as diverse as infection with intracellular pathogens, graft versus host disease, susceptibility to transplantable and spontaneous malignancies, lymphoid homeostasis, and the tendency to auto-immune diseases.

Sex differences in infant rhesus macaque separation-rejection vocalizations and effects of prenatal androgens

Infant and juvenile rhesus macaques exhibit many sexually dimorphic behaviors, including rough and tumble play, mounting, and time spent with nonmother females. This study investigated sex differences in infant rhesus monkey separation-rejection vocalizations (SRVs), and the effects of altering the prenatal hormone environment on these differences. Pregnant females received exogenous androgen (testosterone enanthate), an androgen antagonist (flutamide), or vehicle injections for 30 or 35 days during the second (early) or third (late) trimester of pregnancy. Control females used a greater percentage of coos and arched screams than did control males. In contrast, males used a greater percentage of geckers and noisy screams than did females. Females also had longer SRV bouts, used more calls, and used more types of vocalizations than did males. Mothers were more likely to respond to the SRVs of male infants than to the SRVs of female infants. Prenatal flutamide treatment early in gestation reduced the likelihood that mothers would respond to their male offspring, but prenatal androgen treatment had no effect on response rates of mothers to female offspring. Early, but not late, androgen treatment produced females who vocalized in a male-typical manner. Similarly, early flutamide treatment produced males who displayed more female-typical SRVs. Late flutamide treatments of females produced as much masculinization of SRVs as did early androgen treatment in females. These results demonstrate sex differences in highly emotional vocalizations in infant rhesus macaques and provide evidence that the timing and form of prenatal hormonal exposure influence such vocalizations.

Far-infrared sensor for cirrus (FIRSC): an aircraft-based Fourier-transform spectrometer to measure cloud radiance

We describe an aircraft-based Fourier-transform spectrometer (FTS) designed to measure the Earth outgoing radiance spectrum in the far-infrared-submillimeter spectral range. The instrument features include a rapid-scan FTS to obtain high spatial resolution from a moving aircraft platform, a sensitive two-channel detector, and a CCD camera for recording the nadir cloud scene with each scan record. Such measurements demonstrate the sensitivity of Earth radiance to high clouds and provide spectral data for improving techniques for remote sensing and retrieval of atmospheric and cloud properties.

Granzyme A and B-deficient killer lymphocytes are defective in eliciting DNA fragmentation but retain potent in vivo anti-tumor capacity

Recent studies have demonstrated that granzymes A and B make an important contribution to the clearance of the orthopoxvirus ectromelia, and in graft versus host disease. To test whether granzymes are generally necessary for lymphocyte-mediated cytotoxicity in vivo, we assessed the cytotoxic capacity of granzyme A and/or B-deficient lymphocytes in several perforin-dependent settings. Splenocytes and allogeneic CTL of granzyme A and/or B-deficient mice were defective for induction of DNA fragmentation, but induced significant membrane damage and target cell death. These results correlated well with the behavior of granzyme A/B-deficient CTL and NK cells in three different perforin-dependent tumor models. In a classical assay of NK cell-mediated rejection, granzyme A and/or B-deficient mice inoculated with RMA-S cells were as susceptible to tumor as wild-type mice. Perforin-deficient mice were also considerably more susceptible to tumor initiation by methylcholanthrene than granzyme A and/or B-deficient mice. Furthermore, rejection of the K1735-melanoma expressing MHC class I and II molecules was mediated by adoptively transferred H-2b anti-k CTL from immunized granzyme A and/or B-deficient mice. In summary, these data suggest that granzymes A and B are not critical for most anti-tumor effector functions of NK cells and CTL that are perforin mediated.

Initiation of apoptosis by granzyme B requires direct cleavage of bid, but not direct granzyme B-mediated caspase activation

The essential upstream steps in granzyme B-mediated apoptosis remain undefined. Herein, we show that granzyme B triggers the mitochondrial apoptotic pathway through direct cleavage of Bid; however, cleavage of procaspases was stalled when mitochondrial disruption was blocked by Bcl-2. The sensitivity of granzyme B-resistant Bcl-2-overexpressing FDC-P1 cells was restored by coexpression of wild-type Bid, or Bid with a mutation of its caspase-8 cleavage site, and both types of Bid were cleaved. However, Bid with a mutated granzyme B cleavage site remained intact and did not restore apoptosis. Bid with a mutation preventing its interaction with Bcl-2 was cleaved but also failed to restore apoptosis. Rapid Bid cleavage by granzyme B (<2 min) was not delayed by Bcl-2 overexpression. These results clearly placed Bid cleavage upstream of mitochondrial Bcl-2. In granzyme B-treated Jurkat cells, endogenous Bid cleavage and loss of mitochondrial membrane depolarization occurred despite caspase inactivation with z-Val-Ala-Asp-fluoromethylketone or Asp-Glu-Val-Asp-fluoromethylketone. Initial partial processing of procaspase-3 and -8 was observed irrespective of Bcl-2 overexpression; however, later processing was completely abolished by Bcl-2. Overall, our results indicate that mitochondrial perturbation by Bid is necessary to achieve a lethal threshold of caspase activity and cell death due to granzyme B.

De novo acute hepatitis B infection in a previously vaccinated liver transplant recipient due to a strain of HBV with a Met 133 Thr mutation in the "a" determinant

De novo HBV infection post-liver transplantation (LT) from an anti-HBc seropositive donor rarely presents as acute failure. We report a 42-year-old Caucasian female, HBsAg and anti-HBc seronegative, with primary biliary cirrhosis who received an allograft from a HBsAg negative, anti-HBc seropositive donor. The patient, previously vaccinated years pre-LT, was re-vaccinated against HBV and 1 year post-LT had an anti-HBs titre of 256 IU/l. Two years post-LT, elevated serum aminotransferases and worsening liver function with an INR of 2.0 developed. The HBsAg became positive, anti-HBs undetectable and serum HBV-DNA >2000 pg/ml by hybridisation assay. Liver biopsy revealed significant ballooning degeneration, piecemeal necrosis and positive immunostaining for HBsAg. Progressive liver failure developed followed by sepsis and terminal multi-organ failure. Subsequent analysis of the predominant HBV strain revealed mutations in the "a" determinant: Met 133 Thr (codon change ATG to ACG) and Asn 131 Thr.

CONCLUSION

' Acute de novo HBV infection from an anti-HBc sero-positive donor may occur long after LT despite protective anti-HBs titres post-vaccination secondary to the emergence of "a" determinant mutated strains of HBV.

Dependence of granzyme B-mediated cell death on a pathway regulated by Bcl-2 or its viral homolog, BHRF1

The molecular pathways responsible for apoptosis in response to granzyme B have remained unresolved. Here we present data supporting the notion that granzyme B-mediated cell death is largely dependent on a pathway that is inhibitable by Bcl-2 or its viral analog BHRF1. We used a panel of stably transfected FDC-P1 mouse myeloid cell lines to show that overexpression of functional, wild-type Bcl-2 or BHRF1 rescued cells from granzyme B-mediated apoptosis, whereas mutated (Gly145-->Glu) Bcl-2, or wild-type Bcl-2 directed to the plasma membrane conferred no protection. Overexpression of Bcl-2 resulted in inhibition of multiple parameters of apoptosis in response to purified perforin and granzyme B, including DNA fragmentation, changes in light scatter profile indicating cell shrinkage and increased refractivity, loss of mitochondrial membrane potential and inhibited colony formation in clonogenic assays. Nevertheless, when exposed to cytotoxic lymphocytes, FDC-P1 and YAC-1 cells overexpressing Bcl-2 remained susceptible to death imparted by cytolytic granules, irrespective of whether the granules contained granzyme B. Thus, alternative granzyme B-independent pathways can be activated by intact lymphocytes to overcome Bcl-2-like inhibitors of apoptosis, enabling CTLs to overcome potential viral blocks to granzyme B-mediated cell death.

A biobehavioral framework for examining altered sleep-wake patterns in homeless women

The interactions among psychosocial and environmental stressors and the hypothalamus-pituitary-adrenal-ovarian-immune axes may provide a framework for examining altered sleep-wake patterns in women. Based on this biobehavioral framework, homeless women represent a subgroup of the female population who have many lifestyle factors that might make them vulnerable to sleep disturbances. This article presents a study designed to investigate the self-reported sleep patterns and lifestyle factors associated with the sleep of 50 homeless women, 18-44 years of age, residing in the downtown area of Los Angeles. Results indicated that almost half of the women slept six or less hours a day and had a day/night sleep pattern. A majority of the women reported restless sleep. Drinking beer, using cocaine, anxiety, depression, loneliness, and concerns about safety and money were factors significantly related to altered sleep patterns.

RWJ 67657, a potent, orally active inhibitor of p38 mitogen-activated protein kinase

Tumor necrosis factor-alpha (TNF-alpha), a cytokine secreted by activated monocytes/macrophages and T lymphocytes, has been implicated in several disease states, including rheumatoid arthritis, inflammatory bowel disease, septic shock, and osteoporosis. Monocyte/macrophage production of TNF-alpha is dependent on the mitogen-activated protein kinase p38. RWJ 67657 (4-[4-(4-fluorophenyl)-1-(3-phenylpropyl)-5-(4-pyridinyl)-1H-imidazol -2-yl]-3-butyn-1-ol) inhibited the release of TNF-alpha by lipopolysaccharide (a monocyte stimulus)-treated human peripheral blood mononuclear cells with an IC(50) of 3 nM, as well as the release of TNF-alpha from peripheral blood mononuclear cells treated with the superantigen staphylococcal enterotoxin B (a T cell stimulus), with an IC(50) value of 13 nM. This compound was approximately 10-fold more potent than the literature standard p38 kinase inhibitor SB 203580 in all p38 dependent in vitro systems tested. RWJ 67657 inhibited the enzymatic activity of recombinant p38alpha and beta, but not gamma or delta, in vitro and had no significant activity against a variety of other enzymes. In contrast, SB 203580 significantly inhibited the tyrosine kinases p56 lck and c-src (IC(50) = 5 microM). RWJ 67657 did not inhibit T cell production of interleukin-2 or interferon-gamma and did not inhibit T cell proliferation in response to mitogens. RWJ 67657 inhibited TNF-alpha production in lipopolysaccharide-injected mice (87% inhibition at 50 mg/kg) and in rats (91% inhibition at 25 mg/kg) after oral administration. Based on these favorable biological properties, RWJ 67657 may have use as a treatment for inflammatory diseases.

Intragenic suppressors of Hsp70 mutants: interplay between the ATPase- and peptide-binding domains

ATP hydrolysis and polypeptide binding, the two key activities of Hsp70 molecular chaperones, are inherent properties of different domains of the protein. The coupling of these two activities is critical because the bound nucleotide determines, in part, the affinity of Hsp70s for protein substrate. In addition, cochaperones of the Hsp40 (DnaJ) class, which stimulate Hsp70 ATPase activity, have been proposed to play an important role in promoting efficient Hsp70 substrate binding. Because little is understood about this functional interaction between domains of Hsp70s, we investigated mutations in the region encoding the ATPase domain that acted as intragenic suppressors of a lethal mutation (I485N) mapping to the peptide-binding domain of the mitochondrial Hsp70 Ssc1. Analogous amino acid substitution in the ATPase domain of the Escherichia coli Hsp70 DnaK had a similar intragenic suppressive effect on the corresponding I462T temperature-sensitive peptide-binding domain mutation. I462T protein had a normal basal ATPase activity and was capable of nucleotide-dependent conformation changes. However, the reduced affinity of I462T for substrate peptide (and DnaJ) is likely responsible for the inability of I462T to function in vivo. The suppressor mutation (D79A) appears to partly alleviate the defect in DnaJ ATPase stimulation caused by I462T, suggesting that alteration in the interaction with DnaJ may alter the chaperone cycle to allow productive interaction with polypeptide substrates. Preservation of the intragenic suppression phenotypes between eukaryotic mitochondrial and bacterial Hsp70s suggests that the phenomenon studied here is a fundamental aspect of the function of Hsp70:Hsp40 chaperone machines.

Sensations experienced during removal of tubes in acute postoperative patients

The major purpose of this study was to determine the types and intensity of sensations that patients experience when chest tubes (CTs) and Jackson-Pratt (JP) abdominal tubes are removed. A convenience sample of 62 hospitalized subjects, 31 with CTs and 31 with JP tubes, participated. Each subject was interviewed after tube removal. Sensations were identified, and intensity of sensation was marked on a 100-mm Visual Analogue Scale. Similar sensations were reported by both groups. Intensity of sensation was consistently higher in the JP group. The most frequently reported sensations were pain (77%) on JP tube removal and pulling (90%) upon CT removal.

Anti-viral strategies of cytotoxic T lymphocytes are manifested through a variety of granule-bound pathways of apoptosis induction

Cytotoxic T cells and natural killer cells together constitute a major defence against virus infection, through their ability to induce apoptotic death in infected cells. These cytolytic lymphocytes kill their targets through two principal mechanisms, and one of these, granule exocytosis, is essential for an effective in vivo immune response against many viruses. In recent years, the authors and other investigators have identified several distinct mechanisms that can induce death in a targeted cell. In the present article, it is postulated that the reason for this redundancy of lethal mechanisms is to deal with the array of anti-apoptotic molecules elaborated by viruses to extend the life of infected cells. The fate of such a cell therefore reflects the balance of pro-apoptotic (immune) and anti-apoptotic (viral) strategies that have developed over eons of evolutionary time.

T cell activation signals up-regulate p38 mitogen-activated protein kinase activity and induce TNF-alpha production in a manner distinct from LPS activation of monocytes

p38 mitogen-activated protein kinase (MAPK) (p38) is involved in various cellular responses, including LPS stimulation of monocytes, resulting in production of proinflammatory cytokines such as TNF-alpha. However, the function of p38 during antigenic stimulation of T cells is largely unknown. Stimulation of the human Th cell clone HA-1.70 with either the superantigen staphylococcal enterotoxin B (SEB) or with a specific antigenic peptide resulted in p38 activation and the release of TNF-alpha. MAPK-activated protein kinase-2 (MAPKAPK-2), an in vivo substrate for p38, was also activated by T cell signaling. SB 203580, a selective inhibitor of p38, blocked p38 and MAPKAPK-2 activation in the T cell clone but did not completely inhibit TNF-alpha release. PD 098059, a selective inhibitor of MAPK kinase 1 (MEK1), blocked activation of extracellular signal-regulated kinase (ERK) and partially blocked TNF-alpha production by the clone. In human peripheral T cells, p38 was not activated by SEB, but rather by CD28 cross-linking, whereas in the human leukemic T cell line Jurkat, p38 was activated by CD3 and CD28 cross-linking in an additive fashion. TNF-alpha production by peripheral T cells in response to SEB and anti-CD28 mAb correlated more closely with ERK activity than with p38 activity. Therefore, various forms of T cell stimulation can activate the p38 pathway depending on the cells examined. Furthermore, unlike LPS-stimulated monocytes, TNF-alpha production by T cells is only partially p38-dependent.

The development of novel and selective p56lck tyrosine kinase inhibitors

Early T-cell receptor mediated signal transduction involves the activation of several tyrosine protein kinases. One of these tyrosine kinases, p56lck, is expressed primarily in T-cells and Natural Killer (NK) cells and has been shown to be critical for their proliferative and effector functions. Indandiones have been identified as a potent and selective chemical class that inhibits p56lck.

Postliver transplant allograft reinfection with a lamivudine-resistant strain of hepatitis B virus: long-term follow-up

Lamivudine is a nucleoside analogue with efficacy in the suppression of hepatitis B viral (HBV) replication. In a previously reported study, lamivudine was administered to patients with chronic, actively replicating HBV infection who subsequently underwent liver transplantation. Patients became serum HBV DNA-negative in response to lamivudine before transplantation, which was continued in the post-transplant period. Two of four patients surviving the immediate postoperative period developed allograft reinfection 240 and 409 days post-transplant. The strain of the reinfecting virus was analyzed, and a mutation in the YMDD region of the viral polymerase conferring resistance to lamivudine was discovered. The long term follow-up of these two patients is reported. The first patient developed ascites 16.5 months after allograft reinfection. A transjugular liver biopsy performed 18 months after the emergence of the lamivudine-resistant strain revealed cirrhosis and lobular hepatitis without rejection. The gradient between hepatic vein wedged and free pressures was 13 mmHg, consistent with portal hypertension. The second patient, 16 months after allograft reinfection with the lamivudine-resistant strain, is without clinical evidence of portal hypertension, although liver enzymes remain elevated. Both patients were given a trial of famciclovir, which did not significantly suppress HBV viremia. In conclusion, lamivudine-resistant HBV strains with the YMDD mutation may have an aggressive clinical course with rapid progression to cirrhosis. Famciclovir did not appear to be an effective rescue agent in these two patients.

An innovation in the assessment of future dentists

'The assessment of students is a serious and often tragic enterprise.' The central question in assessment is 'What is one trying to assess?'. Is it factual knowledge, ability to apply and problem solve, clinical competencies or indeed other attributes? The domain being assessed requires appropriate methods. Professionals involved in examination development have identified three characteristics which all assessment methods demand: reliability, validity and feasibility. This article sets out to describe these features.

A novel Alcian yellow-toluidine blue (Leung) stain for Helicobacter species: comparison with standard stains, a cost-effectiveness analysis, and supplemental utilities

Helicobacter pylori (Hp) gastritis is a worldwide problem significantly associated with duodenal and gastric peptic ulcer disease, gastric carcinomas, and MALT-type lymphomas. A simple, rapid, reproducible, reliable, and inexpensive stain to detect the organism in gastric biopsy specimens is thus of great value. To assess the reliability and cost-effectiveness of a novel Alcian yellow-toluidine blue (Leung) stain for Hp, we stained 60 endoscopic mucosal biopsy specimens from patients with Hp gastritis and measured time to detection of organism, Hp numbers (scale, 1-5), and technical costs. We also stained serial 5-microm step sections of 17 of these cases with the Giemsa and modified Steiner (MS) methods, and similar measurements were made. Also, specimens from various normal gastrointestinal sites and metaplastic lesions, as well as four cases each of giardiasis and cryptosporidiosis, were stained with the Leung method. In the subset of 17 cases, the Leung stain enhanced detection time and compared favorably with the Giemsa method, though the MS method was somewhat superior. Hp scores were similar among all groups. Mean time to detection and Hp scores were similar in the larger (n = 60) group stained with hematoxylin and eosin and the Leung stain. Material costs and technologist's time for Giemsa stains, however, were greater than for the Leung stain, and technologist's time for MS was nearly fourfold that of the Leung stain. With the Leung method, mucus from all gastrointestinal sites and metaplastic lesions stained yellow, and this stain provided excellent contrast and morphologic definition in giardiasis and cryptosporidiosis. We suggest that the newly developed Alcian yellow-toluidine blue (Leung) histochemical stain is a good choice as the standard for routine Hp staining because it is the cheapest and easiest to prepare and because pathologists' detection with this stain compares favorably with detection times achieved with more traditional and established methods.

A case of massive thymolipoma

A massive anterior mediastinal tumor was discovered in a 9-year-old girl with long-standing symptoms of asthma. Preoperative computed tomography (CT) scan and magnetic resonance imaging (MRI) results suggested the presence of a thymolipoma, a rare benign tumor of the thymus. Few cases have been reported in the literature, although the histological and radiographic features have been well described. This case confirms previously reported characteristics and also illuminates new aspects of clinical presentation and perioperative management.