Successive Intervals Research Articles

Osteopathische herzfokussierte Palpation und Herzfrequenzvariabilität – Teil 2: Ergebnisse der randomisierten, kontrollierten Pilotstudie

Does osteopathic heart-focused palpation change heart rate variability in people with musculoskeletal pain? Part 1 of the two-part article in the previous issue described the aims, material and methods as well as the participants of the randomized, controlled pilot study; this 2nd part is dedicated to the results.A total of 33 adults (47.7 ± 13.5 years old) with stress and musculoskeletal pain completed the trial with acceptable rates of recruitment (8.25 subjects per site/month), retention (100 %), adherence (100 %), and adverse events (0 %). Heart-focused palpation (HFP; n = 18), but not SHAM (n = 15), significantly increased the root mean square of successive RR interval differences (p = 0.036), standard deviation of the NN intervals (p = 0.009), and ratio of the low-frequency to high-frequency power band (p = 0.026). HFP and SHAM significantly decreased the heart rate (p < 0.001, p = 0.009) but not the stress index and ratio of the Poincaré plot standard deviation along and perpendicular to the line of identity (p > 0.05). A power analysis calculated 72 participants. Taken together, the study was feasible and HFP improved HRV in stressed subjects with musculoskeletal pain, suggesting a parasympathetic effect

Level 4 seizure monitoring unit admissions are associated with reduced long-term health care costs.

This study was undertaken to determine whether admission to dedicated seizure monitoring units (SMUs) result in reduced health care use (HCU). This was a retrospective open cohort study covering the years 2010-2018 of patients residing in Alberta, Canada, who were referred to the Calgary Comprehensive Epilepsy Program and admitted to a level 4 SMU. Patients were required to have ≥3 years pre- and postadmission follow-up. The outcome was the change in trajectory of composite HCU (primary care, specialist outpatient visits, emergency department visits, and hospitalizations) for the 3 years prior to and 3 years following SMU admission using the point of admission as the "index date." Secondary outcomes were HCU limited to specific settings. We excluded the first 30 days following the point of admission to mitigate the confounding admission would have on the postadmission HCU trajectory. We used adjusted restricted maximum likelihood linear and nonlinear effects models to determine trajectories expressed as Canadian dollars. A total of 315 of 600 (53%) patients met eligibility criteria. Mean age was 40 years (SD = 17.4), 176 (56%) were female, 220 (70%) had focal epilepsy, and 60 (19%) had functional seizures or physiologic seizure mimics without epilepsy as adjudicated by the attending physician at the point of discharge. Mean per person health care costs increased by CAD$341.28 (95% confidence interval [CI] = -25.17 to 707.74) for each successive 6-month interval prior to SMU admission (p = .07). Following admission, mean per person costs decreased by CAD$802.34 (95% CI = 699.62-905.06, p < .001) for each successive 6-month interval up to 3 years postdischarge. Similar trends were noted for primary and specialist care, emergency department, admitted care, and when nonlinear models were applied. Admission to an SMU is associated with significant and enduring declines in HCU. Each 6-months following discharge overall HCU declined by a mean of CAD$802.34 and acute inpatient, emergency department, and outpatient physician interactions declined by 25%, 26%, and 18% respectively. Comprehensive epilepsy care not only reduces morbidity and mortality but also reduces cost.

Numerical study of the influence of temperature data error on the determination of frictional heat generation

Subject of research: determination of the friction torque and functions of the specific intensity of heat generation in system of sliding bearings. The purpose of the study: To develop a method for determining the friction torque in sliding bearings using temperature data. Based on computational experiments, study the influence of errors in temperature data on the solution of the inverse problem. Methods and object of research: A system of sliding bearings made of a polymer composite material on which a rotating shaft rests is considered. A mathematical model of the thermal process in the considered system of friction units is presented, taking into account the spatial distribution of temperature and its change over time. The temperature is measured at several points in each bearing. Frictional heat generation is determined by solving the inverse heat conduction problem from the condition that the measured and calculated temperatures are close. To ensure continuous data processing and determine the friction torque during long-term tests, the inverse problem of determining the friction torque from temperature data is solved at successive short time intervals. Then the resulting solutions are «glued together». The main results of the study: With such a restoration, the discrepancy between the specified and restored functions of the specific intensity of heat generation is 10–15 % with an error level in temperature data of 10 %. The developed algorithm for solving the inverse problem of thermal conductivity can be used to determine the friction torques in real systems of self-lubricating sliding bearings.

Detecting the presence of different Retzius periodicities at the population level from repetitive linear enamel hypoplasia among Lufengpithecus lufengensis and Pongo pygmaeus.

Reconstruction of life histories for fossil and living primates draws on rate of enamel layering, termed Retzius periodicity (RP in days) expressed as surface perikymata, during dental crown formation. Disclosure of RP through thin sectioning is destructive; consequently, sample sizes are inadequate to detect the range of RPs present in discrete taxa. We propose an additional method to detect RPs at the population level based on twice-yearly average recurrence of linear enamel hypoplasia (rLEH) in apes shown by prior studies. Casts of teeth from orangutans (Pongo pygmaeus) (n = 40) and Lufengpithecus lufengensis (n = 57) from Late Miocene Shihuiba, China, (133 and 138 LEH, respectively) were recorded with scanning electron microscope (SEM) and confocal microscopy to yield perikymata counts between episodes of LEH. Frequency distributions of aggregated perikymata counts between LEH were compared to frequency distribution of tooth-specific ratios of perikymata counts between successive LEH (this latter step removes effects of RP differences within a sample). Drawing on prior research, two successive intervals between LEH span 1 year on average. Ratios of successive to previous intervals between LEH show that orangutans and Lufengpithecus exhibit two asymmetric intervals centered on 5.3 and 6.7 months, likely reflecting the effect of axial tilt insolation on phenology. Estimated RPs are not unimodal but show a range from 7 to 12 in Lufenpithecus and 8 to 11 in Pongo, comparable to published values. Repetitive LEH is sufficiently regular to detect additional RPs which, in the case of Lufengpithecus, have yet to be demonstrated histologically.

Relationship between heart rate variability and echocardiography indices of cardiac function in healthy individuals.

This study evaluated the relationship between HRV and echocardiography indices of cardiac function. Healthy individuals (N = 30) aged 33 ± 10 years old, underwent short-term resting HRV assessment and transthoracic echocardiography with speckle tracking analysis. Time domain - (i.e. R-R interval, root mean square of successive RR interval difference (RMSSD), standard deviation of normal RR intervals (SDNN) and frequency domain-measures of HRV (i.e. high-frequency power (HF), low-frequency power (LF), high-frequency normalised (HFnorm) and low-frequency normalised (LFnorm)). Echocardiography indices of cardiac function included; Left ventricular ejection fraction (LVEF), left- and right-ventricular global longitudinal strain (LV-GLS, and RV GLS), left atrial strain: left atrial reservoir (LAres), left atrial conduit (LAcon) and left atrial contraction (LACT). The mean values for HRV time-domain measures were: R-R (991 ± 176 ms), SDNN (50.9 ± 21.5 ms), and RMSSD (46.8 ± 29.4 ms); and frequency-domain: LF (727 ± 606 ms2), HF (415 ± 35 ms2), LFnorm (56 ± 19.4) and HFnorm (36.5 ± 18.8). Mean values for indices of cardiac function were LVEF (59.9% ± 2.8%), LV-GLS (19.2% ± 1.4%), RV-GLS (21.7% ± 2.7%), LAres (36.8% ± 6.99%), LAcon (26.2% ± 6.95%) and LACT (12.3% ± 3.56%). There was a significant negative relationship between HF and LV-GLS (r = -0.47, p = 0.01) and RMSSD and LVEF (r = -0.39, p = 0.03) respectively. Heart rate variability measures such as high frequency power and RMSSD are associated with left ventricle systolic function in healthy individuals.

Rasch model of teacher readiness instrument for implementing science learning based on Balinese local wisdom

Local culture has undergone significant shifts and alienations, leading to the neglect of societal values. This situation underscores the need for teachers to be well-prepared to incorporate local wisdom into science education, supporting Cultured-Based Learning. This study, conducted from January to June 2022, aimed to assess the relevance of items in a teacher readiness instrument for implementing local wisdom-based science learning in Bali. An ex post facto research design was employed to analyze the preparedness of 72 science teachers in Bali through a detailed questionnaire. The collected ordinal data were converted into an interval scale using the Method of Successive Interval (MSI) and analyzed using the Rasch Model with the Jamovi application to assess item relevance. The study's findings highlight the cognitive and emotional readiness of science teachers as being in the high category, while collegial support and instructional tools are in the low category. These results suggest that improving collegial features and instructional tools through lesson studies and workshops could enhance the integration of local wisdom into science education in Bali.

Effects of six antipsychotic drug treatment regimens on short-term heart rate variability in patients with schizophrenia.

Many antipsychotic drugs have cardiac side effects due to their pharmacological actions. Heart rate variability (HRV) analysis can be used as a potential indicator of cardiotoxicity in cases where a decrease in HRV occurs after the administration of antipsychotics such as clozapine. The purpose of this study was to explore the effects of 6 antipsychotic drug regimens on short-term HRV in patients with schizophrenia. Data from 164 patients with schizophrenia between January 2018 and June 2023 were retrospectively analysed. Based on the drug used for treatment, the patients were categorised into clozapine combination (clozapine combined with aripiprazole, risperidone or ziprasidone), clozapine alone, olanzapine, aripiprazole, ziprasidone or risperidone groups. Heart rate variability indices were calculated using time domain analysis, including the standard deviation of the RR intervals (SDNN), the root mean square of successive RR interval differences (RMSSD) and the percentage of successive RR intervals over 50ms (PNN50). Compared with the pretreatment period, the SDNN, RMSSD and PNN50 were significantly lower in the clozapine combination, clozapine, olanzapine and aripiprazole groups at the end of weeks 2 and 4 of treatment (P < 0.05). However, these indicators in ziprasidone and risperidone groups did not show this significant decrease (P > 0.05). The effects of clozapine combination and clozapine on HRV were greater than for olanzapine, aripiprazole, ziprasidone or risperidone. Attention should be paid to controlling the dosage of clozapine combination and clozapine and monitoring the patient's electrocardiogram during administration.

Autonomic rehabilitation: Vagal and sympathetic impacts of modified occipitomastoid suture V-spread.

Autonomic rehabilitation using osteopathic manipulative treatment (OMT) to stimulate the vagus nerve may be a good adjunct therapy by physiatrists who treat dysautonomia. Heart rate variability (HRV) may provide quantitative evidence for the benefits of OMT on autonomic nervous system function. Elevated HRV indicates optimal health and reduced mortality risk, whereas low HRV is associated with stress, pain, and chronic disease pathology. To analyze the impact of modified occipitomastoid suture v-spread OMT technique on vagal tone by measuring HRV. Within-participant design with 5-minute HRV measurement pre- and post-OMT treatment. Clinical examination suites. Thirty healthy osteopathic medical students. A modified occipitomastoid suture v-spread treating somatic dysfunction by osteopathic physicians trained in osteopathic neuromusculoskeletal medicine. HRV variables related to vagal tone including root mean square of successive differences (RMSSD), percentage of successive normal sinus RR intervals >50 ms (pNN50), high frequency (HF), Parasympathetic Nervous System Index (PNSI), and Sympathetic Nervous System Index (SNSI). Repeated measures t-test analyzed the difference in mean HRV values after OMT. There were statistically significant increases in each of the HRV measures after OMT. Participants had a mean (95% confidence interval) RMSSD of 50.5 ms (38.3-62.8) at baseline and 55.0 ms (41.2-68.7, p = .013) post-OMT. pNN50 was 24.5% (17.6-31.3, n = 30) at baseline and 28.2% (20.8-35.6, p = .003) post-OMT. HF was 1549.6 ms2 (389.8-2709.4) at baseline and 1901.8 ms2 (618.2-3185.4, p = .103) post-OMT. PNSI was -0.1 (-0.5 to 0.2) at baseline and 0.1 (-0.3 to 1.5, p < .01) post-OMT, and SNSI was 0.2 (-0.1 to 0.6) at baseline and 0.05 (-0.3 to 0.4, p < .01) post-OMT. Normalization, due to high baseline variance, results include RMSSD 1.1 ms (1.0 to 1.1, p = .012), pNN50 1.3 (1.1 to 1.4, p = .011), and HF 1.2 ms2 (1.1 to 1.4, p = .018). Modified occipitomastoid suture v-spread may provide clinical benefit through increased vagal tone and decreased sympathetic activity.

Magnetic Garments Promote Parasympathetic Dominance and Improve Sleep Quality in Male Long-Distance Runners Following a 30 km Run.

This study aimed to investigate the effects of high-intensity running on the autonomic nervous system and sleep quality of male long-distance runners and to examine the impact of wearing magnetic garments on these parameters. Fifteen highly trained male collegiate long-distance runners participated in a randomized, double-blind crossover study. Participants completed two 30 km runs (30k-RUN) during a 10-day training camp. After each run, they wore either magnetic (MAG) or non-magnetic control (CTRL) garments. Sleep quality and heart rate variability (HRV) were assessed using a wrist-worn device before and after each 30k-RUN. Wearing MAG garments post-30k-RUN resulted in significantly longer deep sleep duration compared to CTRL. HRV analysis revealed that the MAG condition led to a significantly higher root mean square of successive RR interval differences and high-frequency power, indicating enhanced parasympathetic activity. The low-frequency to high-frequency ratio was significantly lower in MAG than in CTRL. Perceived recovery scores were significantly higher in MAG than in CTRL. The findings of this study suggest that wearing magnetic garments following high-intensity endurance running may promote parasympathetic dominance and improve sleep quality in male long-distance runners. These findings indicate that magnetic garments may be a practical method for enhancing recovery in athletes following intense training.

Different implications of daytime and nighttime heart rate variability on total burden of cerebral small vascular disease in patients with nondisabling ischemic cerebrovascular events.

This study aimed to explore the relationship between total burden of cerebral small vessel disease (CSVD) and daytime and nighttime heart rate variability (HRV) parameters. Consecutive patients with nondisabling ischemic cerebrovascular events were recruited from the cerebrovascular disease clinic of Changzhou Second People's Hospital between January 2022 and June 2023. A total of 144 enrolled participants were divided into a mild CSVD group (74 patients) and a moderate-to-severe CSVD group (70 patients) based on total burden of CSVD. Various HRV parameters measured during 24-h, 4-h daytime, and 4-h nighttime periods (including natural log-transformed [ln] root mean square of successive RR interval differences [RMSSD], ln absolute power of the high-frequency band [0.15-0.4 Hz] [HF], ln absolute power of the low-frequency band [0.04-0.15 Hz][LF], and LF-to-HF ratio [LF/HF]) were then assessed in the 2 groups. Spearman correlation analysis was used to assess the correlation between total burden of CSVD and HRV parameters. HRV parameters with P-value < 0.05 in correlation analysis were included in the multivariable logistic regression analysis, and restricted cubic spline analysis was performed to assess dose-response relationships. Daytime 4-h lnRMSSD (r = -0.221; P = 0.008) and 4-h lnHF (r = -0.232; P = 0.005) were negatively correlated with total burden of CSVD, and daytime 4-h lnLF/HF (r = 0.187; P = 0.025) was positively correlated with total burden of CSVD. There was no correlation between nighttime HRV parameters and total burden of CSVD. After adjustments were made for potential confounders, daytime 4-h lnRMSSD (OR = 0.34; 95% CI: 0.16-0.76), 4-h lnHF (OR = 0.57; 95% CI: 0.39-0.84), and 4-h lnLF/HF (OR = 2.12; 95% CI: 1.18-3.82) were independent predictors of total burden of CSVD (all P < 0.05). S-shaped linear associations with moderate-to-severe total burden of CSVD were seen for daytime 4h-lnRMSSD (P for nonlinearity = 0.543), 4-h lnHF (P for nonlinearity = 0.31), and 4-h lnLF/HF (P for nonlinearity = 0.502). Daytime parasympathetic HRV parameters are independent influencing factors of total burden of CSVD and may serve as potential therapeutic observation indicators for CSVD.

Improvement of heart rate variability after metabolic bariatric surgery in Korean subjects with obesity.

Cardiovascular autonomic neuropathy (CAN) is a chronic complication of diabetes. As obesity is a major risk factor for CAN, we hypothesized that metabolic bariatric surgery (MBS) could improve CAN indices in Korean patients with obesity. Patients who underwent bariatric surgery between February 2020 and June 2022 were prospectively recruited. CAN was conducted once before surgery and again after surgery, using the Ewing method and heart rate variability (HRV) analysis (standard deviation of the NN interval [SDNN], root mean square of successive RR interval difference [RMSSD], and spectral analysis). A total of 47 patients were included. The mean age was 39.8 ± 8.7 years, 15 (31.9%) were male, and 26 (55.3%) had diabetes. Resting HR before surgery was 81.0 ± 12.3 bpm, which decreased significantly to 68.0 ± 9.3 bpm after surgery (P < 0.001). Changes in HR and BP according to the Valsalva maneuver, postural changes, and handgrip were not significantly different before and after surgery. However, SDNN significantly increased from 25.2 [15.1, 33.5] to 38.0 [25.4, 45.0] ms (P < 0.001), and RMSSD also significantly increased from 17.0 [9.2, 31.8] to 28.2 [15.3, 45.6] ms (P = 0.001). Both low-frequency power (LF) and high-frequency power (HF) increased significantly, and the LF/HF ratio significantly decreased from 2.1 ± 1.6 to 1.3 ± 1.3 (P = 0.010). Loss of weight, fat mass, and lean body mass were independently associated with improving the HRV variables. MBS improved HRV variables, and these changes were mainly associated with postoperative weight loss.

Postpartum Blood Pressure Variability and Heart Rate Variability in Preeclampsia.

Preeclampsia is associated with autonomic dysregulation during pregnancy; however, less is known about autonomic function in the first week postpartum after preeclampsia. We retrospectively analyzed data from a prospective cohort of women with and without preeclampsia. Continuous blood pressure and heart rate were measured with finger plethysmography within 7 days postpartum. Frequency-domain blood pressure and heart rate variability (HRV) were calculated using spectral analysis. Time-domain HRV was calculated as the root mean square of successive RR interval differences. We compared results between those with and without preeclampsia, as well as between those with new-onset preeclampsia, chronic hypertension with superimposed preeclampsia, and normotensive participants. A total of 70 postpartum women were enrolled: 20 normotensive, 29 new-onset preeclampsia, and 21 superimposed preeclampsia. Both low- and high-frequency blood pressure variabilities were higher in those with preeclampsia compared with controls (P=0.04 and P=0.02, respectively). This difference was driven by those with new-onset preeclampsia. The preeclampsia group had lower high-frequency HRV (P<0.005), a higher low-/high-frequency ratio of HRV (P<0.005), and lower time-domain HRV (P=0.01); this difference was seen in those with and without chronic hypertension. Postpartum patients with preeclampsia with and without chronic hypertension had lower HRV compared with normotensive postpartum controls. Higher blood pressure variability was observed only in those with nonsuperimposed preeclampsia, suggesting that the autonomic profile of preeclampsia may differ in patients with chronic hypertension.

Giant Kelvin‐Helmholtz (KH) Waves at the Boundary Layer of the Coronal Mass Ejections (CMEs) Responsible for the Largest Geomagnetic Storm in 20 Years

AbstractStarting in the evening of 10 May 2024 the Earth's magnetosphere was hit by the coronal mass ejections (CMEs) creating the largest geomagnetic storm in 20 years. The CME encounter was characterized by variations of plasma number density and magnetic field. Here, I present the ARTEMIS observations at the lunar orbit during this event. The IMF ranged from −60 to +40 nT both with hour to minutes periodicity with plasma jets propagating in ‐direction within multi‐scale wave structures. Similar signature has been recently reported at the magnetopause by MMS spacecraft (Li et al., 2023, https://doi.org/10.1029/2023GL105539; Nykyri, 2024, https://doi.org/10.1029/2024GL108605) during a strongly southward IMF. Here, I show that the CME boundaries were KH unstable leading to multi‐scale density and magnetic field fluctuations including reconnection jets. The wavelengths varied from 60 to 270 , suggesting that the magnetosphere was periodically exposed to successive intervals of strongly northward and southward IMF leading to enhanced mass and magnetic flux loading.

Do extra-pulmonary triggers or autonomic neural activity affect rhythm control by anti-arrhythmic drugs in patients with post-ablation atrial fibrillation recurrence?

The role of anti-arrhythmic drugs (AADs) in recurrent atrial fibrillation (AF) after catheter ablation (CA) is not fully understood. The aim of this study was to explore the effects of AADs in patients who recurred after AFCA depending on extra-pulmonary vein triggers (ExPVTs) and post-ablation heart rate variability (HRV) parameters. We analyzed 2,036 patients who underwent de-novo AFCA and 486 patients with post-AFCA recurrence who underwent rhythm control with AADs. We investigated the effects of ExPVTs and 3rd month HRV parameters on the post-AFCA recurrence and subsequent AAD responsiveness. A total of 486 out of 2,036 patients developed clinical recurrence of AF and subsequently underwent rhythm control with AADs. 486 out of 310 patients (63.8%) remained free of second recurrence at 1-year. Post-AFCA recurrence was significantly higher in patients with ExPVT [Log-rank p < 0.001, HR 1.45 (1.16-1.83), p = 0.001] or higher 3rd month root mean square of the differences between successive RR intervals (rMSSD) [Log-rank p < 0.001, HR 1.36 (1.11-1.65), p = 0.003] than their counterparts. Patients with ExPVTs during the de-novo procedure had significantly higher 3rd month rMSSD (15.0 [11.0-23.0] vs. 17.0 [11.0-28.0], p = 0.022). Patients with high 3rd month rMSSD had higher rate of ExPVTs during the repeat procedure (n = 160, 41.0% vs. 22.2%, p = 0.019). Among patients with recurrent AF after AFCA, post-AAD recurrence did not differ depending on the presence of ExPVT [Log-rank p = 0.455, HR 1.12 (0.78-1.69), p = 0.436] or 3rd month rMSSD [Log-rank p = 0.457, HR 1.16 (0.87-1.55), p = 0.300]. Post-AAD recurrence did not differ between class IC and III AADs (p for interaction = 0.311). ExPVT and post-procedural high rMSSD are independent risk factors for post-AFCA recurrence but not for AAD response in patients with recurrent AF. AADs may suppress ExPVTs and modulate cardiac autonomic activity after post-AFCA recurrence.

Nondestructively Determining Soluble Solids Content of Blueberries Using Reflection Hyperspectral Imaging Technique

Effectively detecting the quality of blueberries is crucial for ensuring that high-quality products are supplied to the fresh market. This study developed a nondestructive method for determining the soluble solids content (SSC) of blueberry fruit by using a near-infrared hyperspectral imaging technique. The reflection hyperspectral images in the 900–1700 nm waveband range were collected from 480 fresh blueberry samples. An image analysis pipeline was developed to extract the spectrums of blueberries from the hyperspectral images. A regression model for quantifying SSC values was successfully established based on the full range of wavebands, achieving the highest RP2 of 0.8655 and the lowest RMSEP value of 0.4431 °Brix. Furthermore, three variable selection methods, namely the Successive Projections Algorithm (SPA), interval PLS (iPLS), and Genetic Algorithm (GA), were utilized to identify the feature wavebands for modeling. The models calibrated from feature wavebands generated an RMSEP of 0.4643 °Brix, 0.4791 °Brix, and 0.4764 °Brix, as well as the RP2 of 0.8507, 0.8397, and 0.8420 for SPA, iPLS, and GA, respectively. Furthermore, a pseudo-color distribution diagram of the SSC values within blueberries was successfully generated based on established models. This study demonstrated a novel approach for blueberry quality detection and inspection by jointly using hyperspectral imaging and machine learning methodologies. It can serve as a valuable reference for the development of grading equipment systems and portable testing devices for fruit quality assurance.

A Bayesian analysis of heart rate variability changes over acute episodes of bipolar disorder

Bipolar disorder (BD) involves autonomic nervous system dysfunction, detectable through heart rate variability (HRV). HRV is a promising biomarker, but its dynamics during acute mania or depression episodes are poorly understood. Using a Bayesian approach, we developed a probabilistic model of HRV changes in BD, measured by the natural logarithm of the Root Mean Square of Successive RR interval Differences (lnRMSSD). Patients were assessed three to four times from episode onset to euthymia. Unlike previous studies, which used only two assessments, our model allowed for more accurate tracking of changes. Results showed strong evidence for a positive lnRMSSD change during symptom resolution (95.175% probability of positive direction), though the sample size limited the precision of this effect (95% Highest Density Interval [−0.0366, 0.4706], with a Region of Practical Equivalence: [-0.05; 0.05]). Episode polarity did not significantly influence lnRMSSD changes.

Impact of slouching on heart rate variability and cardiovascular health among medical students

Background: Medical students frequently adopt poor postures such as slouching potentially impacting health. Heart rate variability (HRV) serves as an indicator of autonomic nervous system function, correlated with cardiovascular health. Aims and Objectives: The objective of the study was to compare HRV parameters among medical students in three postures: Sitting erect, easy pose (cross-legged), and slouching (stooping head and shoulders). Materials and Methods: A comparative cross-sectional study enrolled 26 male medical students. Participants were instructed to maintain each posture for 5 min while HRV was recorded using a Polar V800. Time domain and frequency domain parameters among different postures were analyzed using Friedman’s test and post hoc tests for pairwise comparisons. P&lt;0.05 was considered significant. Data were expressed as median interquartile range. Results: Significant differences were observed in HRV parameters between postures. The easy pose demonstrated a significantly higher median value of root mean square of differences of successive RR intervals (48.28 ms vs. 35.35 ms) and pNN50% (24.40% vs. 13.62%) compared to slouching. Frequency domain analysis revealed a significantly higher median value of high-frequency (HF) power in easy pose (626.56 ms² vs. 378.15 ms²) and HF normalized unit (33.78 vs. 22.55) compared to slouching. A lower low frequency (LF)/HF ratio and (1.96 vs. 3.43) lower LF normalized unit (66.18 vs. 77.30) was also seen in easy pose. Although statistically not significant, the parasympathetic indicators of HRV were higher in erect sitting compared to slouching posture. Conclusion: Among medical students, adopting the easy pose (cross-legged sitting) appeared to enhance HRV and thus increase parasympathetic activity, whereas adopting slouching postures decreased it.

Correlation of serum zinc and magnesium with reduced heart rate variability in male Parkinson’s disease patients

Background: Parkinson’s disease (PD) is a neurological disorder associated with altered cardiac autonomic function. Heart rate variability (HRV) analysis is a tool to assess the cardiac autonomic status. Altered serum zinc (Zn) and magnesium (Mg) levels are observed in PD. The serum Zn and Mg alteration is associated with nerve function impairment. Objective: To evaluate the relationship between serum zinc, magnesium, and time domain measures of HRV in male patients with PD. Methods: This observational analytical cross-sectional study was conducted in 2023on 30 newly diagnosed male PD patients aged 50-60 years. In this study, 30 healthy volunteers were the control. The 30 patients were divided into different categories based on serum mineral levels. The HRV was recorded by Power Lab 8/35, AD Instruments, Australia and the time domain measures of HRV were used in data analysis. The serum Zn and Mg levels were measured by atomic absorption spectrophotometry. Independent sample ‘t’ test and Pearson’s correlation coefficient test were used for statistical analysis and p&lt;0.05 was considered statistical significance. Results: Significantly higher mean HR (Heart rate) (p&lt;0.01) and significantly lower mean RR (Normal to normal QRS complex) interval,CVRR (Coefficient variation of RR interval) (p&lt;0.01), SDRR (Standard deviation of the RR intervals), SDSD (Standard deviation of the difference between successive RR intervals), RMSSD (Square root of mean squared differences of successive RR intervals), pRR50% (Proportion of RR interval with duration &gt;50 ms) (p&lt;0.001)were observed in PD patients compared to control. In PD patients, significantly lower (p&lt;0.001) serum Zn and significantly higher (p&lt;0.01) serum Mg were observed compared to control. In addition,significant decrement was observed in SDRR, CVRR (p&lt;0.05), SDSD, RMSSD, and pRR50% (p&lt;0.01) in hypozincemic PD patients compared to normozincemic patients. On correlation analysis, significant positive correlations of serum Zn were observed with SDRR (p&lt;0.05),SDSD (p&lt;0.001), RMSSD (p&lt;0.001) and pRR50% (p&lt;0.01). Moreover,serum Mg was positively correlated with SDRR (p&lt;0.05) in PD patients. Conclusion: Hypozincemia and magnesium were directly related to reduced HRV in male PD patients. J Bangladesh Soc Physiol 2023;18(2): 63-71

Association of cardiac autonomic nerve function with serum zinc, calcium and magnesium in female hypothyroid patients

Background: Hypothyroidism is related to impaired cardiac autonomic nerve activity with altered levels of serum Zinc (Zn), Calcium (Ca) ‍and Magnesium (Mg).Altered Serum Zn,Caand Mg levels are also associated with autonomic imbalance and may raise cardiovascular risk.Heart rate variability (HRV) is an important marker for assessing cardiac autonomic nerve function(CANF). Objectives: To evaluate the association of serum Zn, Cal and Mglevels withCANF in female hypothyroid patients. Methods: This analytical cross-sectional study was conducted on 40 female hypothyroid patients aged 18-45 years. Thirty apparently healthy women were control. Serum Zn, Ca and Mg levels were estimated by autoanalyzer and CANF was assessed by time domain analysis of HRV recorded by Power Lab 8/35 AD Instruments, Australia. Statistical analysis was done by Independent sample‘t’ test, One way ANOVA followed by post-hoc Bonferroni test and Pearson’s correlation coefficient test. Results: Among time domain parameters of HRV, standard deviation of the RR intervals (SDRR), coefficient variation of RR interval (CVRR), SD rate, standard deviation of the difference between successive RR intervals (SDSD), square root of mean squared differences of successive RR intervals (RMSSD), proportion of RR interval with duration &gt;50 ms (pRR50%) were significantly lower (p&lt;0.05) in all hypothyroid patients as compared to control. On correlation analysis, serum Zn, Ca and Mg were significantly positively correlated with SDSD(p&lt;0.01, p&lt;0.001,p&lt;0.01) RMSSD(p&lt;0.01, p&lt;0.001, p&lt;0.01), pRR50%(p&lt;0.01, p&lt;0.01, p&lt;0.05)and serum Ca was also positively correlated with SDRR(p&lt;0.05) in hypothyroid patients. Conclusion:Serum ZnCa and Mg were associated with cardiac autonomic dysfunction. in female hypothyroid patients. J Bangladesh Soc Physiol 2023;18(1): 27-34

Age and growth rate estimated by skeletochronology in loggerhead sea turtles from French Mediterranean waters

Abstract Skeletochronology was used to determine the ages of 30 loggerhead sea turtles (Caretta caretta) found in French Mediterranean waters. Histological sections were performed with 30 humeri collected on stranded C. caretta on the coast of Provence and the Gulf of Lion. Lines of arrested growth (LAGs) were used to evaluate age, considering only one period of arrested growth per year. Two successive LAGs delimit an interval that is proportional to the individual’s body growth. In a first step, we created a skeletogram for each individual that identified its LAGs. Secondly, we measured the areas delineating successive intervals to determine individual growth patterns over the years. Two methods were used to deduce sea turtle age from histological sections: the correction factor (CF) method and the growth rate (GR) method, the latter using Von Bertalanffy growth function. Age estimations varied from 4.3 to 24.7 years (mean ± SD = 10.1 ± 4.8) with the CF method and from 6.2 to 25.6 years (mean ± SD = 12.2 ± 5.2) with the GR method, with no significant difference between the methods. The study sample was thus mostly composed of juveniles, which is also the most frequent life stage observed in the study area. The annual curved carapace length growth rate calculated with every LAG interval varied from 1.0 to 6.9 cm/year (mean ± SD = 3.5 ± 1.4, ). High variability in interindividual growth rates were observed, which is of interest in understanding the complex lifecycle of these long-lived marine reptiles.