Xiphoid Bone

Participants wore spandex shorts, a form-fitting shirt, and their own exercise shoes. Forty-two spherical, retro-reflective markers (14mm diameter) were placed, bilaterally, on the lower extremity, pelvis, and trunk (Fig 1). Specifically, markers were placed over the following landmarks: acromion processes, xiphoid process, spinous process of the seventh cervical vertebra (C7), superior aspects of the iliac crests, anterior superior iliac spines, sacrum (midpoint between the posterior superior iliac spines), greater trochanters, lateral and medial femoral epicondyles, lateral and medial malleoli, posterior aspect of the calcanei, and first and fifth metatarsal heads. Plastic shells that contained four, non-collinear markers each were positioned laterally over the thigh and shank [39 (link)]. Marker shells were attached to the lower extremity segments via neoprene wraps and hook and loops fasteners. Once the markers were placed over the appropriate anatomical landmark, a static calibration trial was recorded. Following the static trial, the medial knee and ankle markers were removed so they would not encumber participants during the movement trials.
Marker motion was recorded using motion capture system (Nexus, Vicon Motion Systems Ltd, Centennial, CO) with ten Vicon MX-T20 cameras sampling at 100 Hz. Each camera was calibrated to have less than 0.15 mm residual error. Participants performed three different single leg weight bearing tasks (Fig 2) in the following order: step down from a 16 cm step (SD16), step down from a 24 cm step (SD24), and single leg squat (SLS). Order was not randomized as this was part of a larger clinical study. For each trial of each task, the starting and ending position was standing on both legs with feet in a self-selected position. For the step down tasks, participants stood with both feet on top of a wooden box. From the starting position, they were instructed to stand on one leg, lower the non-stance limb until the heel lightly touched the floor and then return to standing with both feet on the box. For the single leg squat task, participants were instructed shift their weight onto one leg, squat as low as possible with their non-stance limb extended anteriorly, and return to standing on both legs. The position of the non-stance limb was selected to be similar to the step down task. Participants had an opportunity to practice each task. Participants were given approximately 10 seconds between each single trial of each task, and approximately two to three minutes between tasks. The same leg was always tested first. A metronome set at 60 beats per minute was used to help standardize movement speed. Participants were instructed to try to move “down on a beat and up on a beat.” Participants were given feedback to help maintain a consistent movement speed for each individual trial; however, strict adherence to the metronome was not enforced. Upper extremities had to be maintained either at their sides or out to the side. Trials in which subjects lost their balance or used their upper extremities for support on the surrounding bars were recollected. Five trials were collected on each lower extremity for each task. Only the data during right stance was analyzed for this study.

The mice were placed in a 50 mL conical polypropylene centrifuge tube and immersed vertically to the level of the xiphoid process into a water bath at 23°C for 2 hrs (acute stress). The mice were subjected to this stress session once a day for 3 weeks (chronic stress). In our preliminary experiments, gastric ulcer was not produced by single or chronic exposure. Control mice were similarly fasted, followed by removal from their home cages, and subsequent placement in new breeding cages for 2 hrs. These experimental groups were chosen by means of a completely randomized design. Depression-like behaviors were measured with tail-suspension test and forced-swimming test. Immobility time was recorded in both tests during the last 6 min in the total 10 min test-period. After the end of this stress session, the mice were anesthetized with administration of sodium pentobarbital (30 mg/kg). In chronic stress and control mice groups, to avoid the acute influence of the last stress session and to evaluate the influence of chronic stress as a consequence of the cumulative stress effects, mice were sacrified after 1 day from last stress session.

The parents of the participants and the ELC staff provided the demographic information required for the study. The testing sessions took place at the ELC between 8:00 and 10:00. Each participant was fitted with the two HRV measurement devices over three testing sessions. The electrodes on the reverse side of the Polar H10 chest strap were moistened with room temperature water prior to being placed on the participant. The Polar H10 chest strap was then fitted around the participant’s chest just below the chest muscles with the HR sensor placed on the xiphoid process of the sternum. Velcro was sewn onto the reverse side of the chest strap so the size could be adjusted for proper fit around the participant. The PPG finger monitor was placed on the participant’s left-hand index finger. Both the Polar H10 chest strap and the PPG finger monitor automatically connected to the Elite HRV^© app once a signal was detected.
For each participant, the testing sessions were separated by at least one day. If the time between consecutive testing sessions exceeded seven days, the participant data were discarded. One participant was measured at a time and each HRV recording was 3.5 min long with the first 30 s acting as a stabilization period. The recording time was determined based on recommendations from previous studies [14 (link),25 (link)].
Prior to HRV recordings, all participants were measured, seated upright with backs pressed up against the back of the same plastic chair. The chair used for testing sessions was familiar to participants as it was borrowed from the ELC. Once the HRV devices were properly placed, participants remained in a resting state for 2 min. For the HRV measurements, the participants were seated and resting in a quiet room while being read a story. The room temperature was kept consistent for all testing days. The purpose of the storybook was to sustain the attention of participants for the HRV measurement duration without compromising the relaxed and quiet state required for measurements.

At each exam, height, weight, and WC were measured in replicate in light clothing without shoes according to standardized protocol [2 (link),57 (link)]. Height was measured to the nearest 0.2 cm via portable stadiometer (Seca Corporation, Chino, CA), and weight was measured to the nearest 0.1 kg via calibrated balance beam scale. WC was measured midway between the iliac crest and the lowest lateral portion of the rib cage (anteriorly at the point midway between the xiphoid process of the sternum and the umbilicus) using a Seca tape measure, and an average of 2 measures to the nearest 0.5 cm was used. BMI was calculated as weight in kilograms divided by height in meters squared (kg/m²) [8 ].

The site of animal electroacupuncture intervention was consistent with those used in previous experiments (Wang et al., 2015 (link)). Zhong-wan-acupoint (RN12) was located on the intersection of the upper 1/3 and lower 2/3 of the line connecting the xiphoid process and the upper border of the pubic symphysis, wei-shu-acupoint (BL21) was 2 mm adjacent to the spinous process of the 12th thoracic vertebra. Using disposable sterile acupuncture needles (0.25*13 mm, Yunlong Medical Co., Ltd., China) and electrical stimulator (G6805, Qingdao Xinsheng, China). A 20 min EA procedure was performed at a frequency of 2/100 Hz by using current with an intensity of 0.1–1 mA.

60 people received one cc of normal saline (1 ml) as a placebo two minutes before changing from lithotomy to supine position.
Each ephedrine syringe contained 50 mg of ephedrine diluted with 9 ml of distilled water in 10 cc syringes, each cc containing 5 mg of ephedrine. The placebo syringes were in the form of 10 cc syringes containing distilled water, and two minutes before changing the lithotomy position to the supine position, one cc of each was randomly injected intravenously into the patients in the study groups. The patients, surgeons, and anesthesiologists were blinded to the allocation of the patients to the studied groups. All aseptic precautions were conducted before performing the spinal anesthesia. Spinal anesthesia was performed with a #25 needle (SPINAL ANESTHESIA NEEDLE, Dr.J brand, made in Japan, Quincke type) in the sitting position from the third and fourth intervertebral space (midline approach) and by injecting 12.5 mg hyperbaric bupivacaine in the subarachnoid space. Then, the patients were placed in the supine position and received 4 liters of oxygen per minute during the operation through a simple face oxygen mask. Sensory levels were determined by the pinprick test after block (every 15–20 seconds for 3 minutes), and the motor blockade was evaluated using Bromage's criteria until the level of spinal anesthesia was raised to the T8 level.
Cystoscopy was performed in lithotomy position, a ureteric catheter was entered into the upper ureter or renal pelvis and fixed with tape to the indwelling Foley catheter, and patients were placed in the supine position. The patient's supine position changed to the prone position, and renal access was conducted in the prone position under fluoroscopic guidance; superior and inferior bolsters were placed at the xiphoid process cartilage to support the lower rib cage, and at the symphysis pubis, vertical bolsters were put in the standard manner along the lateral sides of the chest.
All vital parameters, including HR and NIBP, were recorded perioperatively the time before spinal anesthesia performing (T0), immediately after spinal anesthesia induction (T1), after the lithotomy position (T2), when lithotomy position changed to the supine position (T3), and then when the patient was placed in the prone position (T4). Afterward, vital signs were documented every 3 minutes for 60 minutes (T5–T25) and finally at the end of surgery time (Tf).
If the systolic blood pressure was under 100 mmHg or less than 20% from the baseline, it was treated with 5 mg ephedrine and increased crystalloid speed. If the heart rate (HR) was under 50 beats/minute, it was treated with 0.75 mg of atropine. The incidence of hypotension, bradycardia, nausea, vomiting, shivering, and other complications were recorded.