A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation.

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

Hive Transplantation Has Minimal Impact on the Core Gut Microbiome of the Australian Stingless Bee, Tetragonula carbonaria.

Bacteria residing in the guts of pollinating insects play a key role in nutrient acquisition, digestion, and resistance to pests and diseases. Imbalances in microbial flora in response to environmental change and stress can therefore impact insect health and resilience. This study is aimed at defining the core gut microbiome of the Australian native stingless bee, Tetragonula carbonaria, and exploring the impact of colony transplantation on gut health. The gut microbiomes of nine forager bees from natural (log) and manufactured (box) hives were examined via 16S rRNA gene amplicon sequencing. Some differences were observed at the ASV level between the microbiomes of log and box hive bees. However, a core microbiome, dominated by Lactobacillus spp., unclassified Acetobacteraceae spp., and Bombella spp., was maintained. Further, the inferred functional potential of the microbiomes was consistent across all individuals. This study highlights that although hive transplantation has an impact on the overall diversity of stingless bee gut microbiomes, it is unlikely to have a significant negative impact on the overall health and resilience of the colony.

Diseased and healthy murine local lung strains evaluated using digital image correlation.

Tissue remodeling in pulmonary disease irreversibly alters lung functionality and impacts quality of life. Mechanical ventilation is amongst the few pulmonary interventions to aid respiration, but can be harmful or fatal, inducing excessive regional (i.e., local) lung strains. Previous studies have advanced understanding of diseased global-level lung response under ventilation, but do not adequately capture the critical local-level response. Here, we pair a custom-designed pressure-volume ventilator with new applications of digital image correlation, to directly assess regional strains in the fibrosis-induced ex-vivo mouse lung, analyzed via regions of interest. We discuss differences between diseased and healthy lung mechanics, such as distensibility, heterogeneity, anisotropy, alveolar recruitment, and rate dependencies. Notably, we compare local and global compliance between diseased and healthy states by assessing the evolution of pressure-strain and pressure-volume curves resulting from various ventilation volumes and rates. We find fibrotic lungs are less-distensible, with altered recruitment behaviors and regional strains, and exhibit disparate behaviors between local and global compliance. Moreover, these diseased characteristics show volume-dependence and rate trends. Ultimately, we demonstrate how fibrotic lungs may be particularly susceptible to damage when contrasted to the strain patterns of healthy counterparts, helping to advance understanding of how ventilator induced lung injury develops.

Mouse lung mechanical properties under varying inflation volumes and cycling frequencies.

Respiratory pathologies alter the structure of the lung and impact its mechanics. Mice are widely used in the study of lung pathologies, but there is a lack of fundamental mechanical measurements assessing the interdependent effect of varying inflation volumes and cycling frequency. In this study, the mechanical properties of five male C57BL/6J mice (29-33 weeks of age) lungs were evaluated ex vivo using our custom-designed electromechanical, continuous measure ventilation apparatus. We comprehensively quantify and analyze the effect of loading volumes (0.3, 0.5, 0.7, 0.9 ml) and breathing rates (5, 10, 20 breaths per minute) on pulmonary inflation and deflation mechanical properties. We report means of static compliance between 5.4-16.1 µl/cmH2O, deflation compliance of 5.3-22.2 µl/cmH2O, percent relaxation of 21.7-39.1%, hysteresis of 1.11-7.6 ml•cmH2O, and energy loss of 39-58% for the range of four volumes and three rates tested, along with additional measures. We conclude that inflation volume was found to significantly affect hysteresis, static compliance, starting compliance, top compliance, deflation compliance, and percent relaxation, and cycling rate was found to affect only hysteresis, energy loss, percent relaxation, static compliance and deflation compliance.

Examining lung mechanical strains as influenced by breathing volumes and rates using experimental digital image correlation.

BACKGROUND: Mechanical ventilation is often employed to facilitate breathing in patients suffering from respiratory illnesses and disabilities. Despite the benefits, there are risks associated with ventilator-induced lung injuries and death, driving investigations for alternative ventilation techniques to improve mechanical ventilation, such as multi-oscillatory and high-frequency ventilation; however, few studies have evaluated fundamental lung mechanical local deformations under variable loading. METHODS: Porcine whole lung samples were analyzed using a novel application of digital image correlation interfaced with an electromechanical ventilation system to associate the local behavior to the global volume and pressure loading in response to various inflation volumes and breathing rates. Strains, anisotropy, tissue compliance, and the evolutionary response of the inflating lung were analyzed. RESULTS: Experiments demonstrated a direct and near one-to-one linear relationship between applied lung volumes and resulting local mean strain, and a nonlinear relationship between lung pressures and strains. As the applied air delivery volume was doubled, the tissue surface mean strains approximately increased from 20 to 40%, and average maximum strains measured 70-110%. The tissue strain anisotropic ratio ranged from 0.81 to 0.86 and decreased with greater inflation volumes. Local tissue compliance during the inflation cycle, associating evolutionary strains in response to inflation pressures, was also quantified. CONCLUSION: Ventilation frequencies were not found to influence the local stretch response. Strain measures significantly increased and the anisotropic ratio decreased between the smallest and greatest tidal volumes. Tissue compliance did not exhibit a unifying trend. The insights provided by the real-time continuous measures, and the kinetics to kinematics pulmonary linkage established by this study offers valuable characterizations for computational models and establishes a framework for future studies to compare healthy and diseased lung mechanics to further consider alternatives for effective ventilation strategies.

The vaginal metabolome and microbiota of cervical HPV-positive and HPV-negative women: a cross-sectional analysis.

OBJECTIVE: Characterise the vaginal metabolome of cervical HPV-infected and uninfected women. DESIGN: Cross-sectional. SETTING: The Center for Health Behavior Research at the University of Maryland School of Public Health. SAMPLE: Thirty-nine participants, 13 categorised as HPV-negative and 26 as HPV-positive (any genotype; HPV+ ), 14 of whom were positive with at least one high-risk HPV strain (hrHPV). METHOD: Self-collected mid-vaginal swabs were profiled for bacterial composition by 16S rRNA gene amplicon sequencing, metabolites by both gas and liquid chromatography mass spectrometry, and 37 types of HPV DNA. MAIN OUTCOME MEASURES: Metabolite abundances. RESULTS: Vaginal microbiota clustered into Community State Type (CST) I (Lactobacillus crispatus-dominated), CST III (Lactobacillus iners-dominated), and CST IV (low-Lactobacillus, 'molecular-BV'). HPV+ women had higher biogenic amine and phospholipid concentrations compared with HPV- women after adjustment for CST and cigarette smoking. Metabolomic profiles of HPV+ and HPV- women differed in strata of CST. In CST III, there were higher concentrations of biogenic amines and glycogen-related metabolites in HPV+ women than in HPV- women. In CST IV, there were lower concentrations of glutathione, glycogen, and phospholipid-related metabolites in HPV+ participants than in HPV- participants. Across all CSTs, women with hrHPV strains had lower concentrations of amino acids, lipids, and peptides compared with women who had only low-risk HPV (lrHPV). CONCLUSIONS: The vaginal metabolome of HPV+ women differed from HPV- women in terms of several metabolites, including biogenic amines, glutathione, and lipid-related metabolites. If the temporal relation between increased levels of reduced glutathione and oxidised glutathione and HPV incidence/persistence is confirmed in future studies, anti-oxidant therapies may be considered as a non-surgical HPV control intervention. TWEETABLE ABSTRACT: Metabolomics study: Vaginal microenvironment of HPV+ women may be informative for non-surgical interventions.

Cigarette smoking is associated with an altered vaginal tract metabolomic profile.

Cigarette smoking has been associated with both the diagnosis of bacterial vaginosis (BV) and a vaginal microbiota lacking protective Lactobacillus spp. As the mechanism linking smoking with vaginal microbiota and BV is unclear, we sought to compare the vaginal metabolomes of smokers and non-smokers (17 smokers/19 non-smokers). Metabolomic profiles were determined by gas and liquid chromatography mass spectrometry in a cross-sectional study. Analysis of the 16S rRNA gene populations revealed samples clustered into three community state types (CSTs) ---- CST-I (L. crispatus-dominated), CST-III (L. iners-dominated) or CST-IV (low-Lactobacillus). We identified 607 metabolites, including 12 that differed significantly (q-value < 0.05) between smokers and non-smokers. Nicotine, and the breakdown metabolites cotinine and hydroxycotinine were substantially higher in smokers, as expected. Among women categorized to CST-IV, biogenic amines, including agmatine, cadaverine, putrescine, tryptamine and tyramine were substantially higher in smokers, while dipeptides were lower in smokers. These biogenic amines are known to affect the virulence of infective pathogens and contribute to vaginal malodor. Our data suggest that cigarette smoking is associated with differences in important vaginal metabolites, and women who smoke, and particularly women who are also depauperate for Lactobacillus spp., may have increased susceptibilities to urogenital infections and increased malodor.

Parent-reported distress in children under 3 years old during preventive medical and dental care.

PURPOSE: This study examined factors related to young children's distress during preventive oral health visits. Additionally, associations between parent-reported child behaviour during the dental visit and during previous medical visits were tested. METHODS: One hundred twenty-two children under 3 years of age enrolled in a government insurance programme for low-income children were seen for examination, prophylaxis, and fluoride application at a university-based dental clinic. Child distress was rated by parents on a numerical rating scale. RESULTS: The average age of children enrolled was 23.5 ± 7.3 months. The majority (55.7 %) were judged to have little or no distress pre-examination. Mild or no distress during the examination was reported for 42.6 % of the children and severe distress was reported for 39.4 %. Intensity of distress during the examination was not associated with the child's age, gender, dental health, or previous experience with dental care. Distress was also unrelated to the caregiver's education level or own dental health. Intensity of distress was associated with the child's pre-dental examination distress and distress during prior medical examinations and injections. CONCLUSIONS: Dental professionals can better anticipate child distress by assessing children before a dental examination and enquiring about previous medical experiences. Strategies to prepare parents and alleviate distress may help children cope with the preventive dental visit.

Improving perception of letters and visual structure of language.

Information about letters and the physical structure of language printed in Roman characters was given to children beginning to read. Experimental investigations coupled three alternative graphic modes of printing upper- and lower-case letters with an instructional intervention termed "Alpha-Beta" which provides practice in letter sorting, matching of letters, associative matching, and memory matching. In respect to graphics, Mode A letters were in standard alphabet form. Mode B provided standard letters with each backed by a unique half-tone (Visually Stippled Alphabet); Mode C provided standard letters with each backed by a unique visual texture (Visually Patterned Alphabet). Pre-posttest change in reading readiness was measured using the Metropolitan Readiness Test. In the first study 224 English-speaking 5- to 6-yr.-old children were tested. In the second there were 158 Spanish-speaking girls and boys 6 to 7 years old. It was predicted that Alpha-Beta intervention involving visually patterned alphabet would lead to the greatest increases in readiness scores. This is confirmed in both studies for children low in reading readiness preexperiment. Children high in reading readiness are less affected. The second experiment involved Spanish-speaking children and investigated intervention by Alpha-Beta against a no-intervention control. This confirms the value of Alpha-Beta per se. Possible explanations for the improvements are identified.

Fatigue, mindset and ecology in the hazard dominant environment.

Ratings made by 47 experienced drivers to 18 items of a Fatigue Advisory are highly consistent. Every item is rated 'very' or 'extremely important' to the safety of inexperienced drivers. In contrast, 'adequacy of knowledge' about fatigue is rated consistently lower. This inconsistency may reflect a culturally based confusion about fatigue. Education and public awareness campaigns need to emphasize that 'immoderate indulgence of driving' is as dangerous to safety as 'immoderate indulgence of alcohol'. A basic challenge is to improve understanding of the manner in which the experience of fatigue emerges during driving. Study of perceptual/cognitive manifestations aided by operational definition of fatigue as a 'declarative state' renders driving fatigue a definite observable subjective condition arising from continuous operation of a vehicle. Specific cognitive symptoms of fatigue such as boredom, tiredness, inattention, etc. emerging with driving fatigue, are circumscribed within the activity of driving itself and also reflect the particular conditions in which driving fatigue occurs. This approach reveals ecological dimensions to the problem. The specific experiences of driving fatigue are seen to emerge as a function of the driver environment relationship in a particular driving environment. It is suggested that the concept of the 'hazard dominant environment' and the compensating landscape perceptions of 'prospect' and 'refuge' proposed by Appleton [(1995) The Experience of Landscape. Wiley, London] in concert with the concept of environmental 'affordances' provided by Gibson [(1979) An Ecological Approach to Visual Perception. Houghton Mifflin, Boston] open promising possibilities for improving environmental education about driving fatigue.

Development of fatigue symptoms during simulated driving.

Why do people sometimes allow themselves to be overcome by fatigue? Ancient human survival may have depended on ignoring fatigue. Its modern occurrence in the absence of strain may further render us insensitive to its warning value. To test whether deliberate monitoring of certain symptoms may help drivers and other workers realize when they need to rest to avoid hazard, the development of fatigue while driving a simulator was objectively measured in terms of how many persons quit driving as a function of time. Some subjects asked to stop after 90 minutes; others lasted 240 minutes. Grouping data from an adapted Pearson [(1957) Journal of Applied Psychology, 44, 186-191] fatigue checklist revealed a curious phenomenon. No matter how long subjects drove before wanting to quit, they still developed much the same subjective level of fatigue at the end. This suggests that people do not differ greatly in how much fatigue they can tolerate but rather how quickly they reach a certain critical level of fatigue. Averaging fatigue scores backwards from the time subjects quit produced a function similar to the quitting function. Similar treatment of the other data revealed certain clusters of symptoms whose development also paralleled the development of fatigue.

The effect of dietary selenium deficiency on acute colorectal mucosal nucleotoxicity induced by several carcinogens in the rodent.

BACKGROUND: Selenium (SE) has been inversely associated with colon cancer risk. Two potential mechanisms of this effect were examined in a rodent short-term carcinogenesis assay: whether dietary SE deficiency altered the initiation aspect of carcinogenesis in the colon, and whether SE altered carcinogen metabolism. SETTING: Animal laboratory. SUBJECTS: 52 Sprague-Dawley rats, divided into a SE diet deficient group (0.002 parts per million; ppm) and a SE sufficient (0.2 ppm) group. ENDPOINTS: Weight, serum SE concentration, and karryorhectic index (KI), which is a measure of acute carcinogen induced nuclear toxicity in the colonic mucosa. METHODS: After three weeks of acclimation to the diets, eight animals from each dietary group were injected with one of the following: dimethylhydrazine (DMH), a colon specific carcinogen, its metabolite, methylazoxymethanol (MAM), or 0.9% sodium chloride. Twenty-four hours after injection the colons were removed, blood drawn, and the stained colons assayed for nuclear aberrations. RESULTS: No weight differences were generated by the dietary variations. Low-dietary SE resulted in serum SE declining markedly in the study period to 6 ng/ml versus 33 ng/ml in the SE sufficient group. Diet alone, and variations in weight gain, did not alter the KI. Both carcinogens greatly increased the KI in both the left and right colon. A SE-deficient diet was associated with a higher KI in both carcinogen groups in the right colon, with statistical significance for both the left and right colon in the MAM injection group. CONCLUSIONS: Dietary SE deficiency is associated with increased KI of the colon in MAM treated rats. SE, therefore, has a protective effect in the initiation phase of carcinogenesis.

Perineal sigmoidectomy for sigmoid procidentia: report of a case.

Although rectal procidentia is not an uncommon disease, presentation of more proximal segments of the large bowel through the anus is extremely rare. We report a male patient with an acute sigmoid prolapse secondary to a large villous adenoma acting as the lead point. Since the prolapsed segment was irreducible and exhibited signs of vascular compromise, an intraoperative colonoscopy and perineal sigmoidectomy with a primary anastomosis was carried out. Postoperatively, the patient did well and was discharged 5 days after his operation. Recognition of the difference between sigmoid and rectal procidentia should influence the surgeon's choice of operation, along with the viability of the prolapsed bowel and overall condition of the patient.

Factors affecting perception of outdoor public environments.

Comfort and related perceptions are important in respect to use of outdoor public places. In a laboratory, 170 persons viewed four such places on slides and rated them on 10 dimensions, namely, "comfortable," "playful," "serious," "active," "unsafe," "good," "tense," "interesting," "gloomy," and "pleasing." Instructions were used to vary time of day and the number of people present at the location. It was found that women (n = 96) regard outdoor environments as more threatening than do men (n = 74) which suggests that women feel more vulnerable to untoward acts and that public places are rated less desirous at dusk than at dawn, presumably because dusk is followed by night and dawn by day. It was also discovered that such public environments are rated better than deserted places when occupied by two or more persons. Some of these results are consistent with the Prospect-Refuge Theory of Appleton.

Experimental intercomparisons of younger and older driver perceptions.

Drivers over sixty-five years of age and drivers under twenty-one years of age have the highest relative frequency of crashes resulting in injury and death. Attitudes of these two groups were investigated using questionnaires. One hundred twenty-seven (127) younger and one hundred eight (108) older drivers who had voluntarily registered in driving education courses satisfactorily completed questionnaires about attitudes and behaviors pertinent to safe driving. Half of each sample rated the average driver in their age group and the average driver in the opposite age group as regarded thirty-three attitudes promoting safe driving, twenty courteous safe driving behaviors and eleven discourteous, unsafe driving behaviors. Data shows that younger drivers viewed older drivers as overly cautious, too slow to act and apt to cause accidents, and rated their peers as overly aggressive and discourteous. Older drivers characterized younger drivers as deficient in courtesy and safe driving practices, and they rated their peers as cautious, courteous, and aware of age-related limitations. The findings indicate that each group was aware that safety hazards are created by drivers in their age group. It also shows that both groups had a positive impression of some driving practices of their age group, and that the other group was depreciated. The outcome confirms and expands upon conclusions derived from less formal studies about how drivers perceive other roadway users. It also specifies the extent to which particular attitudes and driving practices are attributed to the peer group and to the opposite age group.

Self-perception of the ability to work in the cold.

Accumulating evidence of beneficial effects from physical exertion must be balanced against increased risk of cardiac arrest during performance. There is evidence that, by using such cues as heart rate, individuals can monitor their level of exertion perceptually. We undertook experiments to discover whether temperature and heart rate interact to affect self-perception when the effective temperature is moved downard from the comfort zone. In the first pilot study, 36 males practiced a new game, SwedeBall, for a period of 20 minutes. Twelve were randomly assigned to play at a temperature of 22 degrees C, another 12 to play at 0 degrees C, and the remaining 12 to play at -7 degrees C. The players showed tendencies toward an overall improvement in self-evaluations after brief practice, with more favorable responses when the temperatures were lower. In a second experiment on different days, 8 men pedaled a standard bicycle mounted as a wind trainer in a controlled environment chamber where the effective temperature was set at 26 degrees C, 8 degrees C, or -10 degrees C. The first 5-minute ride at each temperature was at a heart rate of 120 beats per minute (bpm), the second at 140 bpm, and a third at 160 bpm. We measured ratings of perceived effort (RPE), thermal impression, discomfort, perceived rate of speed, and projected endurance. The result confirmed that RPE was lowered by temperature when heart rate was constant. The data also showed that the lowered temperatures uniformly produced more favorable self-perceptions on the other four scales. The outcome is related to physiological problems that might arise when temperature depresses heart rate and reduces the experience of effort.

Comparing headphone and speaker effects on simulated driving.

Twelve persons drove for three hours in an automobile simulator while listening to music at sound level 63dB over stereo headphones during one session and from a dashboard speaker during another session. They were required to steer a mountain highway, maintain a certain indicated speed, shift gears, and respond to occasional hazards. Steering and speed control were dependent on visual cues. The need to shift and the hazards were indicated by sound and vibration effects. With the headphones, the driver's average reaction time for the most complex task presented--shifting gears--was about one-third second longer than with the speaker. The use of headphones did not delay the development of subjective fatigue.

Application of automated human voice delivery to warning devices in an intensive care unit: a laboratory study.

Environmental concerns about the delivery of warning messages in intensive care units exist in the belief that conventional non-verbal alarm signals are perceived to be threatening by some patients. There is also a significant opportunity for error in interpretation by fatigued or anxious personnel. A laboratory study was undertaken to determine whether human subjects made fewer errors when messages regarding ICU related tasks were delivered by tape recorded human voice than by the non-verbal signals derived from devices in the ICU. Results demonstrated a statistically significant superiority of human voice messages over non-verbal signals. It is concluded that taped human voice messages merit field trials in intensive care units.

Contributions to the history of psychology: LX. Remarks about S. Howard Bartley, as a scholar, scientist, and human being.

The scholarly record of S. Howard Bartley (1902-1988) evokes respect because it shows quality, diversity, and quantity. Bartley's publications are well known and have been frequently cited in the literature of psychology, physiology, and optometry. His contributions to encyclopedias, handbooks, and other summative records of knowledge are legion. Notwithstanding his acknowledged eminence, unusual factors in his early upbringing worked to limit ability to gain full recognition for his work. Acting as a person, Bartley exhibited major talent in artistic areas and created endless delights for friends and colleagues in work and social settings.