Evaluation of Perioperative Intestinal Motility Using a Newly Developed Real-Time Monitoring System During Surgery.

BACKGROUND: This study aimed to investigate perioperative intestinal motility using a novel bowel sound monitoring system in patients undergoing breast and neck surgery. MATERIALS AND METHODS: This study enrolled 52 patients who underwent surgery for breast cancer, thyroid tumor, and parathyroid tumor at Kochi Medical School from May 2019 to June 2020. Perioperative bowel sound counts (BSCs) were recorded using a newly developed real-time analysis system in the operating theater. Clinical information and BSC per minute (cpm) data during the preanesthetic, preoperative, operative, postoperative periods, and period in recovery room were obtained to compare between each period. The Mann-Whitney U and Pearson Chi-square tests were used in data analysis. RESULTS: The BSCs during the intraoperative period and postoperative period were significantly decreased compared to those during the preanesthetic period (0.07 cpm versus [vs.]. 1.4 cpm, P = 0.002 and 0.1 cpm vs. 1.4 cpm, P = 0.025, respectively). The preoperative BSC with a preanesthetic BSC < 1.4 was significantly lower than that with a preanesthetic BSC ≥ 1.4 (0.40 cpm vs. 1.78 cpm, P = 0.006). The preanesthetic, preoperative, and postoperative BSCs with an intraoperative BSC < 0.07 were significantly lower than those with an intraoperative BSC ≥ 0.07 (0.48 cpm vs. 2.83 cpm, P = 0.007; 0.40 cpm vs. 1.81 cpm, P = 0.008; and 0.07 cpm vs. 0.42 cpm, P = 0.006, respectively). CONCLUSION: The real-time bowel sound analysis system demonstrated an inhibitory effect associated with anesthetic and surgical stress on intestinal motility as the BSC sequentially.

Truth or Myth: Intra-abdominal Pressure Increases in the Lithotomy Position.

STUDY OBJECTIVE: To determine if there were differences in intra-abdominal pressure (IAP) in the supine, low lithotomy, and high lithotomy positions. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: Twenty-nine women undergoing surgery for prolapse or stress incontinence. INTERVENTIONS: Relevant medical history, including the pelvic organ prolapse quantification stage, body mass index, and airway grade (Mallampati score), was abstracted from patients' medical charts. IAP was measured in centimeters of water (cmH2O) on the day of their surgery before induction of general or intravenous anesthesia using a T-doc air charged urodynamic catheter (Laborie Aquarius; Ontario, Canada) placed in a patient's vagina (for patients with incontinence) or rectum (for patients with prolapse). MEASUREMENTS AND MAIN RESULTS: IAP was measured in 3 positions: supine (legs at 0°), low lithotomy (legs in Yellowfin stirrups at 45°; Allen Medical, Acton, MA), and high lithotomy (legs at 90°). The means ± SDs IAP for the groups were as follows: in the supine position, 18.6 cmH2O ± 7.6; low lithotomy, 17.7 cmH2O ± 6.6; and high lithotomy, 17.1 cmH2O ± 6.3. In the same women, there was a significant decrease in IAP from the supine to high lithotomy positions, with a mean difference of 1.4 cmH2O ± 3.7, p = .05. Similarly, there was a significant, though smaller, decrease in mean IAP when moving from the supine to low lithotomy positions in these same women (mean decrease of 0.9 cmH2O ± 1.5, p = .004). Neither change is clinically significant based on previous research that suggests 5 cmH2O is a clinically significant change. CONCLUSION: Placing patients' legs in a low or high lithotomy position does not result in a clinically significant increase in IAP. Therefore, surgeons and anesthesiologists can consider positioning patients' lower extremities in stirrups while patients are awake to minimize discomfort and possibly reduce the risk of nerve injuries.

Micropore Closure Rates following Microneedle Application at Various Anatomical Sites in Healthy Human Subjects.

INTRODUCTION: The continuous availability of open micropores is crucial for a successful microneedle (MN) drug delivery strategy. However, micropore lifetime depends on intrinsic skin functional and anatomical characteristics, which vary significantly at different anatomical sites. OBJECTIVE: This pilot study explored if differences exist in micropore closure timeframes at 3 anatomical sites - upper arm, volar forearm, and abdomen. METHODS: Healthy subjects (n = 35) self-identifying as Asian (n = 9), Bi-/multiracial (n = 2), Black (n = 9), Latino (n = 6), and White (n = 9) completed the study. The upper arm, volar forearm, and abdomen were treated with MNs; skin impedance and transepidermal water loss (TEWL) were measured at baseline and post-MN to confirm micropore formation. Impedance was measured for 3 days to evaluate micropore lifetime. Measurements of L*, which quantifies the skin lightness/darkness, were made using a tristimulus colorimeter. Micropore lifetime was determined by comparing baseline and post-MN impedance measurements, and micropore closure half-life was predicted using mathematical modeling. RESULTS: Post-MN increase in TEWL and decrease in impedance were significant (p < 0.05), confirming successful micropore formation at all anatomical sites. When data were analyzed according to subject self-identified racial/ethnic groups, the mean micropore closure time at the abdomen (63.09 ± 13.13 h) was longer than the upper arm (60.34 ± 14.69 h) and volar forearm (58.29 ± 16.76 h). The predicted micropore closure half-life at anatomical sites was the abdomen (25.86 ± 14.96 h) ≈ upper arm (23.69 ± 13.67 h) > volar forearm (20.2 ± 11.99 h). Differences were not statistically significant between groups. Objective categorization by L* showed that the darker skin may be associated with longer micropore closure time at the abdomen site. CONCLUSIONS: Our results suggest that anatomical site of application may not be a source of significant variability in micropore closure time. These findings may help reduce the number of physiological parameters that need to be explicitly considered when developing drug products to support MN-assisted drug delivery strategies.

Abdominal Stiffness Evaluation in Massage for Constipation.

According to the experience of nurses and physiotherapists, the abdomen of constipated people becomes softer after abdominal massage. However, the relationship between the decrease in abdominal stiffness and the benefits of abdominal massage has not been examined quantitatively and is unclear. Furthermore, devices for measuring stiffness have been designed to measure relatively hard areas such as the shoulders and do not take into account the lateral outflow of the target tissue, which can be a problem when measuring the stiffness of soft areas such as the abdomen. To address these issues, this study presents a stiffness sensor suitable for measuring abdominal stiffness and investigates the relationship between the reduction in abdominal stiffness and the benefits of abdominal massage. The solution to prevent the lateral outflow of the target is the realization of a stopper, including a contact detection device, which enables a wide-area contact around the targeted area. The sensor consists of a stopper, probe, spring, and time-of-flight (ToF) sensors. The probe and spring provide appropriate pressure and deformation to the abdomen, whereas the stopper prevents the probe from being pushed into the abdomen more than necessary. The ToF sensor measures the deformation length when the deformation is stopped by the stopper. The abdominal stiffness can be derived from the deformation length. The investigation results indicate that the reduction in abdominal stiffness corresponds to the improvement of the stool condition or the maintenance of a healthy stool condition, whereas the maintenance of abdominal stiffness indicates the maintenance or deterioration of the stool condition.

Beat the heat: Culex quinquefasciatus regulates its body temperature during blood feeding.

Mosquitoes are regarded as one of the most dangerous animals on earth. Because they are responsible for the spread of a wide range of both human and animal pathogens, research of the underlying mechanisms of their feeding behavior and physiology is critical. Among disease vector mosquitoes, Culex quinquefasciatus, a known carrier of West Nile virus and Western Equine Encephalitis, remains relatively understudied. As blood-sucking insects, adaptations (either at the molecular or physiological level) while feeding on warm blood are crucial to their survival, as overheating can result in death due to heat stress. Our research aims to determine how Cx. quinquefasciatus copes with the heat associated with warm blood meal ingestion and possibly uncover the adaptations this species uses to avoid thermal stress. Through the use of thermographic imaging, we analyzed the body temperature of Cx. quinquefasciatus while blood feeding. Infrared thermography has allowed us to identify a cooling strategy, evaporative cooling via the production of fluid droplets, and an overall low body temperature in comparison to the blood temperature during feeding. Understanding Cx. quinquefasciatus' adaptations and the strategies they employ to reduce their body temperature while blood feeding constitutes the first step towards discovering potential targets that could be used for their control.

Mechanical tension and spontaneous muscle twitching precede the formation of cross-striated muscle in vivo.

Muscle forces are produced by repeated stereotypical actomyosin units called sarcomeres. Sarcomeres are chained into linear myofibrils spanning the entire muscle fiber. In mammalian body muscles, myofibrils are aligned laterally, resulting in their typical cross-striated morphology. Despite this detailed textbook knowledge about the adult muscle structure, it is still unclear how cross-striated myofibrils are built in vivo Here, we investigate the morphogenesis of Drosophila abdominal muscles and establish them as an in vivo model for cross-striated muscle development. By performing live imaging, we find that long immature myofibrils lacking a periodic actomyosin pattern are built simultaneously in the entire muscle fiber and then align laterally to give mature cross-striated myofibrils. Interestingly, laser micro-lesion experiments demonstrate that mechanical tension precedes the formation of the immature myofibrils. Moreover, these immature myofibrils do generate spontaneous Ca2+-dependent contractions in vivo, which, when chemically blocked, result in cross-striation defects. Taken together, these results suggest a myofibrillogenesis model in which mechanical tension and spontaneous muscle twitching synchronize the simultaneous self-organization of different sarcomeric protein complexes to build highly regular cross-striated myofibrils spanning the length of large muscle fibers.

The impact of intra-abdominal pressure on perioperative outcomes in laparoscopic cholecystectomy: a systematic review and network meta-analysis of randomized controlled trials.

BACKGROUND: Laparoscopic cholecystectomy involves using intra-abdominal pressure (IAP) to facilitate adequate surgical conditions. However, there is no consensus on optimal IAP levels to improve surgical outcomes. Therefore, we conducted a systematic literature review (SLR) to examine outcomes of low, standard, and high IAP among adults undergoing laparoscopic cholecystectomy. METHODS: An electronic database search was performed to identify randomized controlled trials (RCTs) that compared outcomes of low, standard, and high IAP among adults undergoing laparoscopic cholecystectomy. A Bayesian network meta-analysis (NMA) was used to conduct pairwise meta-analyses and indirect treatment comparisons of the levels of IAP assessed across trials. RESULTS: The SLR and NMA included 22 studies. Compared with standard IAP, on a scale of 0 (no pain at all) to 10 (worst imaginable pain), low IAP was associated with significantly lower overall pain scores at 24 h (mean difference [MD]: - 0.70; 95% credible interval [CrI]: - 1.26, - 0.13) and reduced risk of shoulder pain 24 h (odds ratio [OR] 0.24; 95% CrI 0.12, 0.48) and 72 h post-surgery (OR 0.22; 95% CrI 0.07, 0.65). Hospital stay was shorter with low IAP (MD: - 0.14 days; 95% CrI - 0.30, - 0.01). High IAP was not associated with a significant difference for these outcomes when compared with standard or low IAP. No significant differences were found between the IAP levels regarding need for conversion to open surgery; post-operative acute bleeding, pain at 72 h, nausea, and vomiting; and duration of surgery. CONCLUSIONS: Our study of published trials indicates that using low, as opposed to standard, IAP during laparoscopic cholecystectomy may reduce patients' post-operative pain, including shoulder pain, and length of hospital stay. Heterogeneity in the pooled estimates and high risk of bias of the included trials suggest the need for high-quality, adequately powered RCTs to confirm these findings.

Intra-abdominal Pressure Changes During Hip Arthroscopy: A Prospective Multicenter Study.

PURPOSE: To evaluate intra-abdominal pressure changes during hip arthroscopy and define its relationship with other patient related variables. METHODS: A prospective multicenter study evaluating intra-abdominal pressure (IAP) in patients undergoing arthroscopic treatment of femoroacetabular impingement was performed. The IAP was measured indirectly by a bladder catheter (AbViser Autovalve Intra-abdominal pressure monitor) and documented every 30 minutes during the entire procedure. The following risk factors were analyzed: traction time, duration surgery, previous abdominal surgery, capsule repair, psoas tenotomy, and surgical approach. RESULTS: One hundred and five patients with symptomatic femoroacetabular impingement that underwent hip arthroscopy met the inclusion criteria. There were significant differences in the IAP between the preoperative measurement of IAP and the IAP at different time points during surgery (P < .01). The IAP increased continuously from the commencement of surgery (considered as time point from portal establishment) until the first 60 minutes. After first 60 minutes of surgery, the IAP did not increase significantly. There were no significant associations between increased IAP and the risk factors analyzed. CONCLUSIONS: IAP increases significantly during the first 60 minutes of hip arthroscopy; it then stabilizes for the duration of surgery before decreasing just after the completion of surgery. The highest recorded IAP was not associated with additional complications. No symptomatic intra-abdominal hypertension was documented. Finally, patient- and procedure-specific risk factors did not predict changes in IAP. Systemic monitoring of IAP during the hip arthroscopy procedure can easily and effectively be done, allowing the surgeon to early detect any significant change. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Kidney Hyperfiltration After Nephrectomy: A Mechanism to Restore Kidney Function in Living Donors.

Living donor kidney transplantation (LDKT) is the treatment of choice for patients with end stage renal disease (ESRD). Up to now, the studies reporting the impact of nephrectomy in living kidney donors to their future kidney function were limited. Most living donors undergo recovery of kidney function after nephrectomy owing to remnant kidneys' capability to compensate nephron loss through adaptive hyperfiltration. However, hyperfiltration may fail and turn out to be maladaptive, causing deterioration of donors' kidney function and increasing risk of chronic kidney disease (CKD) in long term. Hyperfiltration is caused by increased in kidney blood flow and glomerular hypertrophy. Both conditions are regulated by various factors. The adaptive hyperfiltration in the early phase after nephrectomy may play important role in determining long term kidney function, but factors affecting the process are still unclear. Hyperfiltration may also be influenced by donors' characteristics such as age, body mass index (BMI), family related to the recipient, arterial stiffness and intraoperative intrabdominal pressure. Further study to understand the mechanism of hyperfiltration is needed so that kidney transplant centers could anticipate its failure and the detrimental effects of nephrectomy in the future.

Anisotropic non-rigid Iterative Closest Point Algorithm for respiratory motion abdominal surface matching.

Surface registration is a one of the crucial and actual problems of computer aided surgery. This paper presents the modification of the non-rigid Iterative Closest Point Algorithm which takes into account an anisotropic noise model and landmarks as guided correspondence at the transformation step in every iteration. The presented approach was validated on human abdominal briefing surface data from a time-of-flight camera. We took the median of the resulting measures and the outcome is presented: the median of means of surfaces distance was at the same level for both variants of the ICP algorithm and is comparable with the isotropic variant, the median of mean landmark position errors decreased by 0.93 units (over 20% improvement) and the median of percentage of single correspondences in target point cloud increased by 11.96%. The results showed that the introduction of the anisotropic model of noise for the ToF camera allows for the improvement the percentage of target cloud points which had only one correspondent over 10% impartment and additional weighting of markers also improves the measure of the quality of finding real correspondents over 20% improvement. In the examined dataset, where the average initial distance between the clouds of points in the inspiratory and expiration is equal to approx. 7.5 mm, a more than 10% improvement in the quality of the correspondence improves the accuracy of matching the surface within 1 mm which is a significant value in application of minimally invasive image guided interventions.

Evaluation of Quantum Dot Skin Penetration in Porcine Skin: Effect of Age and Anatomical Site of Topical Application.

BACKGROUND: Pig skin is a widely acknowledged surrogate for human skin for in vitro/ex vivo skin penetration studies with application for small molecules and nanosystems. We have investigated the influence of biological factors such as age and anatomical site on the penetration and distribution of nanoparticles (2.1 nm hydrophilic CdTe/CdS quantum dots: QDs) in adult pig skin (APS), weanling pig skin (WPS) and newborn pig skin (NBPS) at two different anatomical sites (ear and abdomen). METHODS: QDs in saline were applied to 1 × 1 cm2 skin (62.5 pmol/cm2) with 2-min finger rubbing using a standardized protocol. After 6- or 24-h incubation on Franz diffusion cells, tape stripping (×10) followed by manual follicular casting was conducted. Cadmium in QDs was quantified using inductively coupled plasma mass spectrometry for all samples. The presence of QDs in similarly treated skin samples was also captured using multiphoton tomography. RESULTS: QDs were mainly localized in hair follicles after 6 and 24 h of exposure with no cadmium detected in the Franz cell receptor compartment regardless of pig age or anatomical site. The amount of QDs deposited in the follicles was similar at 6 h but higher on APS and WPS ears compared to NBPS ears at 24 h. This is associated with the high follicle density and small follicle diameter of the NBPS compared to the smaller density of much larger follicles on the APS. NBPS showed consistent QD distribution for ear and abdomen up to 24 h. CONCLUSIONS: There is minimal penetration of QDs through pig skin. Density and diameter of follicles in association with age of pigs and application site influenced the amount of QDs deposited in follicles. The structure of the stratum corneum, follicle density and diameter of NBPS are similar to human skin suggesting that NBPS is an appropriate model for human skin in the evaluation of topical applications of a range of chemicals including nanosystems.

Kinematics of Stewart Platform Explains Three-Dimensional Movement of Honeybee's Abdominal Structure.

The Stewart platform is a typical parallel mechanism, used extensively in flight simulators with six degrees of freedom. It is rarely found in animals and has never been reported to regulate and control physiological activities. Now an equivalent Stewart platform structure is found in the honey bee (Hymenoptera: Apidae: Apis mellifera L.) abdomen to explain its three-dimensional movements. The stereoscope and scanning electron microscope are used to observe the internal structures of honeybees' abdomens. Experimental observations show that the muscles and intersegmental membranes connect the terga with the sterna and guarantee the honey bee abdominal movements. From the perspective of mechanics, a Stewart platform is evolved from the lateral connection structure of the honey bee abdomen, and the intrasegmental muscles between the sternum and tergum function as actuators between planes of the Stewart platform. The extraordinary structure provides various advantages for a honey bee to complete a variety of physiological activities. This equivalent Stewart platform structure can also be used to illustrate the flexible abdominal movements of other insects with the segmental abdomen.

A Pilot Study for Estimating the Cardiopulmonary Signals of Diverse Exotic Animals Using a Digital Camera.

Monitoring the cardiopulmonary signal of animals is a challenge for veterinarians in conditions when contact with a conscious animal is inconvenient, difficult, damaging, distressing or dangerous to personnel or the animal subject. In this pilot study, we demonstrate a computer vision-based system and use examples of exotic, untamed species to demonstrate this means to extract the cardiopulmonary signal. Subject animals included the following species: Giant panda (Ailuropoda melanoleuca), African lions (Panthera leo), Sumatran tiger (Panthera tigris sumatrae), koala (Phascolarctos cinereus), red kangaroo (Macropus rufus), alpaca (Vicugna pacos), little blue penguin (Eudyptula minor), Sumatran orangutan (Pongo abelii) and Hamadryas baboon (Papio hamadryas). The study was done without need for restriction, fixation, contact or disruption of the daily routine of the subjects. The pilot system extracts the signal from the abdominal-thoracic region, where cardiopulmonary activity is most likely to be visible using image sequences captured by a digital camera. The results show motion on the body surface of the subjects that is characteristic of cardiopulmonary activity and is likely to be useful to estimate physiological parameters (pulse rate and breathing rate) of animals without any physical contact. The results of the study suggest that a fully controlled study against conventional physiological monitoring equipment is ethically warranted, which may lead to a novel approach to non-contact physiological monitoring and remotely sensed health assessment of animals. The method shows promise for applications in veterinary practice, conservation and game management, animal welfare and zoological and behavioral studies.

Spontaneously hypertensive rats have greater impairments in regulating abdominal temperature than brain cortex temperature following physical exercise.

This study aimed to evaluate the changes in brain (Tbrain) and abdominal (Tabd) temperatures in spontaneously hypertensive rats (SHRs) following fatiguing exercise. Male normotensive Wistar rats (NWRs) and SHRs were used at 16 weeks of age. Their arterial pressure was measured by tail plethysmography prior to the experiments to confirm the hypertensive status of the SHRs. Then, the rats underwent implantation of an abdominal temperature sensor to measure Tabd and a guide cannula in the frontal cortex to enable the insertion of a thermistor to measure Tbrain. After a familiarization period, each animal was subjected to incremental speed exercises until fatigue in either a temperate (25 °C) or warm (32 °C) environment, followed by a 60-min post-exercise period at the same temperature at which they exercised. Tbrain, Tabd and tail-skin temperature (Tskin) were measured every min throughout the experiments. SHRs exhibited higher Tabd values than NWRs, and these higher values were transiently and persistently observed at 25 °C and 32 °C, respectively. For example, at 32 °C, Tabd was 0.84 °C higher in SHRs at the 25th min (large effect size). In contrast, regardless of the ambient temperature, SHRs exhibited similar Tbrain values as NWRs, indicating preserved Tbrain regulation following exercise in hypertensive rats. SHRs presented higher Tskin during the last half of the post-exercise period at 25 °C, whereas no inter-group differences were observed at 32 °C. In conclusion, the present results highlight that SHRs, an animal model that mimics uncontrolled essential hypertension in humans, exhibited greater impairments in regulating Tabd than Tbrain during the post-exercise period.

A Novel Cue-Induced Abdominal Reaction Analysis for Internet Gaming Disorder.

Individuals with Internet gaming disorder (IGD) frequently play online games to achieve satisfaction. Numerous signal processing questions regarding the negative consequences and characteristic respiration in a long-term sitting posture remain unanswered. This study recruited 50 individuals with high-risk and low-risk IGD (HIGD and LIGD); these participants were taught to perform a specific respiration during game-film stimuli. The instantaneous frequencies on abdominal movement (fDF) were calculated with ensemble empirical mode decomposition (EEMD). The difference value (ΔfDF) between rest and stimulus statuses was calculated and found that HIGD showed ΔfDF values of 0.060 during positive stimuli and 0.055 during negative stimuli before the exercise but 0.020 and 0.016, respectively, after the exercise. However, the ΔfDF value for those with LIGD during negative stimuli before the exercise was 0.013, and it increased to 0.025 after the exercise. This is the first approach to IGD discrimination toward abdominal response with EEMD.

The mechanical leg response to vibration stimuli in cave crickets and implications for vibrosensory organ functions.

We investigate the influence of leg mechanics on the vibration input and function of vibrosensitive organs in the legs of the cave cricket Troglophilus neglectus, using laser Doppler vibrometry. By varying leg attachment, leg flexion, and body posture, we identify important influences on the amplitude and frequency parameters of transmitted vibrations. The legs respond best to relatively high-frequency vibration (200-2000 Hz), but in strong dependence on the leg position; the response peak shifts progressively over 500-1400 Hz towards higher frequencies following leg flexion. The response is amplified most strongly on the tibia, where specialised vibrosensory organs occur, and the response amplitude increases with the increasing frequency. Leg responses peaking at 800 and 1400 Hz closely resemble the tuning of the intermediate organ receptors in the proximal tibia of T. neglectus, which may be highly sensitive to positional change. The legs of free-standing animals with the abdomen touching the vibrating substrate show a secondary response peak below 150 Hz, induced by body vibration. Such responses may significantly increase the sensitivity of low-frequency receptors in the tibial accessory organ and the femoral chordotonal organ. The cave cricket legs appear suitable especially for detection of high-frequency vibration.

Oviposition-like central pattern generators in pregenital segments of male and female grasshoppers.

Grasshoppers produce an extraordinary oviposition behavior that is associated with multiple specializations of the skeletal and neuromuscular systems in the posterior abdomen, including a central pattern generator (CPG) in the female's terminal abdominal ganglion. Two pairs of shovel-shaped appendages, the ovipositor valves on the abdomen tip, excavate the soil for deposition of eggs. By contrast, the sexually monomorphic pregenital region of the abdomen is without appendages. Morphological homologues of ovipositor muscles and efferent neurons in the eighth abdominal segment are nevertheless present in pregenital segments of males and females. In both sexes, a robust rhythmic motor program was induced in pregenital segments by the same experimental methods used to elicit oviposition digging. The activity, recorded extracellularly, was oviposition-like in burst period (5-6 s) and homologous muscle phase relationships, and it persisted after sensory inputs were removed, indicating the presence of pregenital CPGs. The abdomen exhibited posterior-going waves of activity with an intersegmental phase delay of approximately 1 s. These results indicate that serially homologous motor systems, including functional CPGs, provided the foundation for the evolution of oviposition behavior.

Vocalization in caterpillars: a novel sound-producing mechanism for insects.

Insects have evolved a great diversity of sound-producing mechanisms largely attributable to their hardened exoskeleton, which can be rubbed, vibrated or tapped against different substrates to produce acoustic signals. However, sound production by forced air, while common in vertebrates, is poorly understood in insects. We report on a caterpillar that 'vocalizes' by forcing air into and out of its gut. When disturbed, larvae of the Nessus sphinx hawkmoth (Sphingidae: Amphion floridensis) produce sound trains comprising a stereotyped pattern of long (370 ms) followed by multiple short-duration (23 ms) units. Sounds are emitted from the oral cavity, as confirmed by close-up videos and comparing sound amplitudes at different body regions. Numerical models using measurements of the caterpillar foregut were constructed to test hypotheses explaining sound production. We propose that sound is generated by ring vortices created as air flows through the orifice between two foregut chambers (crop and oesophagus), a mechanism analogous to a whistling kettle. As air flows past the orifice, certain sound frequencies are amplified by a Helmholtz resonator effect of the oesophagus chamber. Long sound units occur during inflation, while short sound units occur during deflation. Several other insects have been reported to produce sounds by forced air, but the aeroacoustic mechanisms of such sounds remain elusive. Our results provide evidence for this mechanism by showing that caterpillars employ mechanisms similar to rocket engines to produce sounds.

Effects of pregnancy on skin properties: A biomechanical approach.

BACKGROUND: A woman's skin is dramatically affected by pregnancy. Its biomechanical properties are critical for resisting highly stressed areas. The aim of this work was to evaluate the impact of pregnancy on the mechanical properties of skin, as well as to evaluate the imprint that pregnancy leaves on the skin after delivery. MATERIALS AND METHODS: Suction tests using a cutometer were performed on 15 non-pregnant women and 26 pregnant women at 8 months of pregnancy and 4 months after delivery. Areas of abdomen and thighs were studied. RESULTS: Significant differences between the non-pregnant and 8-month pregnant groups were observed. Our data demonstrate that skin becomes less elastic and less deformable on the abdomen during pregnancy. On the thighs, a loss of elasticity and firmness was also observed. At 4 months after delivery, the skin did not return to its initial state. CONCLUSION: This study showed that the mechanical properties of skin changed drastically during pregnancy compared to the non-pregnant condition and that these properties remain altered 4 months after delivery. In addition to alterations in abdominal skin during pregnancy, we also observed mechanical changes on the thighs, which are less subject to stretching.

Causal effect of intra-abdominal pressure on maximal voluntary isometric hip extension torque.

PURPOSE: Intra-abdominal pressure (IAP) has been recently shown to be associated specifically with maximal voluntary isometric contraction (MVC) torque of hip extension, although the causal relationship remains unclear. The present study aimed to elucidate whether IAP has a causal effect on hip extension MVC torque. METHODS: IAP during hip extension MVC was changed by controlling the lung volume (i.e., depth of inspiration). Twelve healthy males conducted MVCs of hip extension during breath-hold at full inspiration (inspiratory condition) or expiration (expiratory condition), or during normal breath-hold (normal condition). IAP during MVCs was measured a pressure transducer placed in the rectum. RESULTS: The IAP during hip extension MVC was significantly higher in inspiratory condition (132.0 ± 46.1 mmHg) than in the other two conditions and also higher in normal condition (104.6 ± 35.9 mmHg) than in expiratory condition (77.0 ± 39.1 mmHg). The hip extension MVC torque was significantly higher in inspiratory condition (297.7 ± 82.7 N m) than in expiratory condition (266.4 ± 84.5 N m). In each condition, the hip extension MVC torque correlated with IAP during the MVC task. CONCLUSION: The current results suggest that IAP has a positive causal effect on hip extension MVC torque and that a sufficient increase in IAP directly leads to an enhancement of hip extension MVC torque.