A global bioheat model with self-tuning optimal regulation of body temperature using Hebbian feedback covariance learning

Genetic diversity and selection signatures in Hainan black goats revealed by whole-genome sequencing data

Understanding the genetic characteristics of indigenous goat breeds is crucial for their conservation and breeding efforts. Hainan black goats, as a native breed of south China's tropical island province of Hainan, possess distinctive traits such as black hair, a moderate growth rate, good meat quality, and small body size. However, they exhibit exceptional resilience to rough feeding conditions, possess high-quality meat, and show remarkable resistance to stress and heat. In this study, we resequenced the whole genome of Hainan black goats to study the economic traits and genetic basis of these goats, we leveraged whole-genome sequencing data from 33 Hainan black goats to analyze single nucleotide polymorphism (SNP) density, Runs of homozygosity (ROH), Integrated Haplotype Score (iHS), effective population size (Ne), Nucleotide diversity Analysis (Pi) and selection characteristics. Our findings revealed that Hainan black goats harbor a substantial degree of genetic variation, with a total of 23 608 983 SNPs identified. Analysis of ROHs identified 53 710 segments, predominantly composed of short fragments, with inbreeding events mainly occurring in ancient ancestors, the estimates of inbreeding based on ROH in Hainan black goats typically exhibit moderate values ranging from 0.107 to 0.186. This is primarily attributed to significant declines in the effective population size over recent generations. Moreover, we identified 921 candidate genes within the intersection candidate region of ROH and iHS. Several of these genes are associated with crucial traits such as immunity (PTPRC, HYAL1, HYAL2, HYAL3, CENPE and PKN1), heat tolerance (GNG2, MAPK8, CAPN2, SLC1A1 and LEPR), meat quality (ACOX1, SSTR1, CAMK2B, PPP2CA and PGM1), cashmere production (AKT4, CHRM2, OXTR, AKT3, HMCN1 and CDK19), and stress resistance (TLR2, IFI44, ENPP1, STK3 and NFATC1). The presence of these genes may be attributed to the genetic adaptation of Hainan black goats to local climate conditions. The insights gained from this study provide valuable references and a solid foundation for the preservation, breeding, and utilization of Hainan black goats and their valuable genetic resources.

Genome-wide scans for selection signatures in indigenous pigs revealed candidate genes relating to heat tolerance

Heat stress is a major problem that constrains pig productivity. Understanding and identifying adaptation to heat stress has been the focus of recent studies, and the identification of genome-wide selection signatures can provide insights into the mechanisms of environmental adaptation. Here, we generated whole-genome re-sequencing data from six Chinese indigenous pig populations to identify genomic regions with selection signatures related to heat tolerance using multiple methods: three methods for intra-population analyses (Integrated Haplotype Score, Runs of Homozygosity and Nucleotide diversity Analysis) and three methods for inter-population analyses (Fixation index (F_ST), Cross-population Composite Likelihood Ratio and Cross-population Extended Haplotype Homozygosity). In total, 1 966 796 single nucleotide polymorphisms were identified in this study. Genetic structure analyses and F_ST indicated differentiation among these breeds. Based on information on the location environment, the six breeds were divided into heat and cold groups. By combining two or more approaches for selection signatures, outlier signals in overlapping regions were identified as candidate selection regions. A total of 163 candidate genes were identified, of which, 29 were associated with heat stress injury and anti-inflammatory effects. These candidate genes were further associated with 78 Gene Ontology functional terms and 30 Kyoto Encyclopedia of Genes and Genomes pathways in enrichment analysis (P < 0.05). Some of these have clear relevance to heat resistance, such as the AMPK signalling pathway and the mTOR signalling pathway. The results improve our understanding of the selection mechanisms responsible for heat resistance in pigs and provide new insights of introgression in heat adaptation.

A Potential Objective Sign of Central Sensitization: Referred Pain Elicited by Manual Gluteus Minimus Muscle Exploration is Coincident with Pathological Autonomic Response Provoked by Noxious Stimulation

Referred pain/sensation provoked by trigger points suits the nociplastic pain criteria. There is a debate over whether trigger points are related to a peripheral phenomenon or central sensitization (CS) processes. Referred pain is considered a possible sign of CS, which occurs probably mainly due to the abnormal activity of the immune and autonomic nervous systems. To confirm abnormal autonomic reactivity within the referred pain zone of active trigger points, a new diagnostic tool, the Skorupska Protocol® (the SP test®), was applied. The test uses noxious stimulation (10 minutes of dry needling under infrared camera control) as a diagnostic tool to confirm abnormal autonomic nervous system activity. A response to the SP test® of healthy subjects with referred pain sensations provoked by latent trigger points (LTrPs) stimulation was not explored before. The study aims at examining if LTrPs can develop an autonomic response. Methods. Two groups of healthy subjects, (i) gluteus minimus LTrPs with referred pain (n = 20) and (ii) control (n = 27), were examined using the SP test®. Results. Abnormal autonomic activity within the referred pain zone was confirmed for all analyzed LTrPs subjects. 70% of control subjects had no feature of vasodilatation and others presented minor vasomotor fluctuations. The size of vasomotor reactivity within the referred pain zone was LTrPs 11.1 + 10.96% vs. control 0.8 + 0.6% (p < 0.05). Conclusions. Noxious stimulation of latent TrPs induces abnormal autonomic nervous system activity within the referred pain zone. The observed phenomenon supports the concept of central nervous system involvement in the referred pain patomechanizm.

Amplified Vasodilatation within the Referred Pain Zone of Trigger Points Is Characteristic of Gluteal Syndrome-A Type of Nociplastic Pain Mimicking Sciatica

Gluteal syndrome (GS) mimicking sciatica is a new disease that has been recently recognized and included in the International Classification of Diseases, 11th Revision. The present study examines nociplastic pain involvement in GS and sciatica patients using a new Skorupska protocol (SP) test that provokes amplified vasodilatation in the area of expected muscle-referred pain. A positive test is confirmed if there is (i) a development of autonomic referred pain (AURP) and (ii) an increase in the delta of average temperature (Δ₸°) > 0.3 °C at the end of the stimulation and during the observation SP phases. Chronic GS (n = 20) and sciatica (n = 30) patients were examined. The SP test confirmed muscle-referred pain for (i) all GS patients with 90.6% positive thermograms (Δ₸° 0.6 ± 0.8 °C; maximum AURP 8.9 ± 13.6% (both p < 0.05)) and (ii) those sciatica (n = 8) patients who reported pain sensation during the test with 20.6% positive thermograms (Δ₸° 0.7 ± 0.7 °C; maximum AURP 15.1 ± 17.8% (both p < 0.05)). The remaining sciatica (n = 22) patients did not report pain during the test and presented a Δ₸° decrease and the AURP size below 1%. Conclusion: Amplified vasodilatation suggesting nociplastic pain involvement was confirmed for all GS and sciatica patients who reported painful sensations in the zone typical for gluteus minimus referred pain during the test.

The Automatization of a New Thermography Method Using Invasive Nociceptive Stimulation to Confirm an Autonomic Phenomenon within a Trigger Point Referred Pain Zone

The trigger points (TrPs) related to chronic low back pain that mimic sciatica have been lately recognized and included in the International Classification of Diseases, 11th Revision. This study examined the MATLAB software utility for the objective stratification of low back pain patients using the Minimally Invasive Procedure (MIP). The two diagnostic MIP parameters were: average temperature (ΔTavr) and autonomic referred pain (AURP). Chronic sciatica patients with TrPs (n = 20) and without TrPs (n = 20) were examined using the MIP. A significant increase in both parameters was confirmed for the thigh ROI of the TrP-positive patients, with ΔTavr being the leading parameter (p = 0.016, Exp(β) = 2.603). A continued significance of both parameters was confirmed from 6′00″ to 15′30″ (p < 0.05). The maximum AURP value was confirmed at 13′30″ (p < 0.05) (TrPs(+) 20.4 ± 19.9% vs. TrPs(-) 3.77 ± 9.14%; p = 0.000; CI (0.347,0.348)).

Skin temperature maps as a measure of carotid artery stenosis

In this study, the effect of carotid artery stenosis on the neck skin temperature maps was investigated. With the presence of stenosis, alterations in the carotid artery hemodynamics bring about changes in the heat transfer to the surrounding tissue. This is expected to be captured in the resulting temperature map over the external neck skin surface; possibly it correlates to the presence of stenosis. A total of twenty carotid artery samples, from ten patients with both sides normal (0% stenosis), stenosis (>50%) on one side, and stenosis (>50%) on both sides, were studied. Duplex Ultrasound and infrared (IR) thermography examinations were performed. A computational study, on an ideal 3-dimensional (3D) carotid artery and jugular vein model encapsulated with a solid neck tissue phantom resembling the human neck, was carried out. Incorporating the patient-specific geometrical (depth of artery and stenosis) and flow (peak systolic and end diastolic inlet velocity) boundary conditions, conjugate bio-heat transfer was studied using a finite volume numerical scheme. Simulation results and in-vivo thermal maps show that the average temperature on the external neck skin surface is significantly higher for normal patients (32.82 ± 0.53 °C versus 32.00 ± 0.37 °C, p < 0.001). Furthermore, the thermal region of interests (TROIs) were extracted from the in-vivo thermal images, which both qualitatively and quantitatively distinguish the normal and diseased cases. This study suggests the potential of thermal feature-based screening of patients with carotid artery stenosis.

Infrared (IR) thermography as a potential screening modality for carotid artery stenosis

In the present study, an infrared (IR) thermal camera was used to map the temperature of the target skin surface, and the resulting thermal image was evaluated for the presence of carotid artery stenosis (CAS). In the presence of stenosis in the carotid artery, abnormal temperature maps are expected to occur on the external skin surface, which could be captured and quantified using IR thermography. A Duplex Ultrasound (DUS) examination was used to establish the ground truth. In each patient, the background-subtracted thermal image, referred to as full thermal image, was used to extract novel parametric cold thermal feature images. From these images, statistical features, viz., correlation, energy, homogeneity, contrast, entropy, mean, standard deviation (SD), skewness, and kurtosis, were calculated and the two groups of patients (control and diseased: a total of 80 carotid artery samples) were classified. Both cut-off value- and support vector machine (SVM)-based binary classification models were tested. While the cut-off value classification model resulted in a moderate performance (70% accurate), SVM was found to have classified the patients with high accuracy (92% or higher). This preliminary study suggests the potential of IR thermography as a possible screening tool for CAS patients.

TWO-DIMENSIONAL FINITE ELEMENT MODEL TO STUDY THERMO BIOMECHANICS IN PERIPHERAL REGIONS OF HUMAN LIMBS DUE TO EXERCISE IN COLD CLIMATE

Human beings are equipped with thermo sensitivity, thermoregulation and thermo protection for maintaining the structure and function of their body organs. The thermoregulatory responses and disturbances caused by physical activity in thermo biomechanics of human body organs are not well understood. The mechanism of thermoregulation exhibits a beautiful coordination of biophysical process in order to balance distribution caused by a biothermal system due to physical exercise and other abnormal conditions. In view of above, a model has been developed to study the thermal dynamics in peripheral region of human limbs immediately after exercise under cold climatic conditions. The human limb is assumed to be of cylindrical shape. The peripheral region of limb is divided into three natural components namely epidermis, dermis and subdermal tissues. Appropriate boundary conditions have been framed based on the physical condition of the problem. Finite difference has been employed for time variable and the finite element method is employed along radial and angular direction. The numerical results have been used to obtain temperature profiles in the peripheral region immediately after continuous exercise for a two-dimensional unsteady state case. These results have been used to analyze the thermal disturbances caused by the different intensities of physical exercise in the peripheral region of human limbs. Such a model can be developed to study the generated thermal information which can be useful to biomedical science to analyze the impact of thermal stress on mechanism of thermoregulation causing thermal injuries like heat cramps, heat exhaustion and heat stroke. The results give the idea about the capacity of biothermo mechanisms of human limbs in counting balance. The thermal stress is caused by different intensities of physical exercise. These results can be useful for the biomedical scientists to understand the thermal discomfort caused by different intensities of physical exercise and the time period of rest required to overcome discomfort. Further, the result can be useful to biomedical scientists for developing protocols for physical exercise and rest required by the subject for different intensities of physical exercise and prevent thermal injuries in the workers and sportsmen.

BREAST THERMOGRAPHY AS A POTENTIAL NON-CONTACT METHOD IN THE EARLY DETECTION OF CANCER: A REVIEW

This review paper discusses recent research achievements in medical thermography with concerns about the possibility of early breast cancer detection. With the advancements in infrared (IR) technology, image processing methods, and the pathophysiological-based knowledge of thermograms, IR screening is sufficiently mature to be utilized as a first-line complement to both health managing and clinical prognosis. In addition, it explains the performance and environmental conditions in identifying thermography for breast tumor imaging under strict indoor controlled environmental circumstances. An irregular thermogram is indicated as a significant biological risk marker for the presence or growth of breast tumors. Breast thermography is completely non-contact, with no form of radiation and compression. It is useful for all women of all ages, for pregnant and breastfeeding women, for women with implants, for women with dense or fibrocystic breasts, for women on hormone replacement therapy, and for pre or post menopausal women.

Breast thermography is specifically worthwhile during the early stages of fast tumor growth, which is not yet recognizable by mammography as thermography is a physiological test while mammography is an anatomical one. Often, physiological changes precede anatomical changes. This early detection of irregular tissue liveliness gives breast thermography the potential to be greatly useful and economical as an imaging program and provides the opportunity to apply non-invasive treatment to reform breast tissue activity. The non-radiating nature of thermography also permits repeated images. Thus, changes can be compared over time and the results of protective approaches can be observed to ensure utmost care of breast cells.

OCULAR TEMPERATURE DISTRIBUTION: A MATHEMATICAL PERSPECTIVE

Mathematical modeling has proven to be a viable alternative for investigating the temperature distribution inside the human eye. This is due to its ability to overcome the limitations infrared (IR) thermography; the leading method in ocular temperature measurement. A wide range of mathematical studies on the ocular temperature distribution during various conditions have been published in the literature. In this paper, we carry out an in-depth review of the various mathematical models of the eye that have been developed in the past. Various problems and the implications from the mathematical predictions of these studies are discussed. The future directions of studies in ocular temperature distribution are deliberated.

STUDY OF HUMAN THERMOREGULATION: ADAPTIVE OPTIMIZATION CONTROL THEORY ANALYSIS

An example of homeostasis is temperature regulation at a desired level; this physiological process leads to the preservation of a stable biological environment. A control-theory–based model permits a biomedical engineer to understand the complex operation of thermoregulation, by converting general information to knowledge, and can be integrated to see how systemic parameters influence the entire system. The thermal inputs organized in the hypothalamus to activate thermoregulation responses to heat and cold stimuli, with the widely accepted set-point hypothesis for the regulation of body temperature from a control systems point of view, are, however, not entirely known. There are circumstances (e.g. fever) in which the presumed set-point mechanism appears to break down. This paper evaluates a novel set-level adaptive optimal thermal control paradigm inspired by Hebbian covariance synaptic adaptation, previously proposed based on its potential to predict the homeostatic respiratory system. It introduces a Hebbian feedback covariance learning (HFCL) concept in order to align a neuronal network into the analysis of the thermoregulation system. Hebbian theory is concerned with how neurons connect among themselves to become engrams. The passive-active mathematical model for simulating human thermoregulation during exercise was compared in cool, warm, and hot environments, and then was translated into MATLAB to predict thermoregulation. The two-node core and shell model predictions are comparable with observed thermoregulation responses from the existing literature. The thermoregulation changes with respect to proportionality constant and sensitivity of the receptors. A reasonably general agreement with the measured mean group data of earlier performed laboratory exercise studies was obtained for peak temperature, although it tended to overpredict the core body temperature.

Prediction and parametric analysis of thermal profiles within heated human skin using the boundary element method

In this paper, an axisymmetric model of the human skin is developed to simulate the steady-state temperature distribution during contact with a hot solid. Simulations are carried out using the boundary element method. This study seeks to investigate the feasibility of using the boundary element method in the studies of burn. A sensitivity analysis is carried out to examine the effects of various parameters on the temperature distribution inside the skin during burn. Furthermore, a statistical analysis based on the Taguchi method is performed to determine the combination of factors that produce the desired outcome (least increase in temperature). In order to validate the accuracy of the numerical scheme, results obtained using the boundary element method are compared with the solutions obtained using the more established finite-element method.

Boundary element method with bioheat equation for skin burn injury

Burns are second to vehicle crashes as the leading cause of non-intentional injury deaths in the United States. The survival of a burn patient actually depends on the seriousness of the burn. It is important to understand the physiology of burns for a successful treatment of a burn patient. This has prompted researchers to conduct investigations both numerically and experimentally to understand the thermal behaviour of the human skin when subjected to heat injury. In this study, a model of the human skin is developed where the steady state temperature during burns is simulated using the boundary element method (BEM). The BEM is used since it requires boundary only discretion and thus, reduces the requirement of high computer memory. The skin is modeled as three layered in axisymmetric coordinates. The three layers are the epidermis (uppermost), dermis (middle) and subcutaneous fat. Burning is applied via a heating disk which is assumed to be at constant temperature. The results predicted by the BEM model showed very good agreement with the results obtained using the finite element method (FEM). The good agreement despite using only linear elements as compared to quadratic elements in the FEM model shows the versatility of the BEM. A sensitivity analysis was conducted to investigate how changes in the values of certain skin variables such as the thermal conductivity and environmental conditions like the ambient convection coefficient affect the temperature distribution inside the skin. The Taguchi method was also applied to identify the combination of parameters which produces the largest increase in skin temperature during burns.