Circuital modelling in muscle tissue impedance measurements.

Electrical impedance spectroscopy (EIS) stands as a widely employed characterization technique for studying muscular tissue in both physio/pathological conditions. This methodology commonly involves modeling tissues through equivalent electrical circuits, facilitating a correlation between electrical parameters and physiological properties. Within existing literature, diverse equivalent electrical circuits have been proposed, varying in complexity and fitting properties. However, to date, none have definitively proven to be the most suiTable for tissue impedance measurements. This study aims to outline a systematic methodology for EIS measurements and to compare the performances of three widely used electrical circuits in characterizing both physiological and pathological muscle tissue conditions. Results highlight that, for optimal fitting with electrical parameters relevant to tissue characterization, the choice of the circuit to be fitted closely hinges on the specific measurement objectives, including measurement parameters and associated physiological features. Naturally, this necessitates a balance between simplicity and fitting accuracy.

Association between muscular tissue desaturation and acute kidney injury in older patients undergoing major abdominal surgery: a prospective cohort study.

PURPOSE: Present study was designed to investigate the association between muscular tissue desaturation and acute kidney injury (AKI) in older patients undergoing major abdominal surgery. METHOD: A total of 253 patients (≥ 65 years old) who underwent abdominal surgery with expected duration ≥ 2 h were enrolled. Muscular tissue oxygen saturation (SmtO2) was monitored at quadriceps and bilateral flanks during surgery. Muscular desaturation was defined as SmtO2 < 90% baseline lasting for > 60 s. The primary outcome was the incidence of AKI within postoperative 7 days. The association between muscular desaturation and AKI was analyzed by multivariable logistic regression model. The secondary outcomes indicated the other complications within postoperative 30 days. RESULTS: Among 236 patients, 44 (18.6%) of them developed AKI. The incidence of muscular desaturation at quadriceps was 28.8% (68/236). Patients with muscular desaturation had higher incidence of AKI than those without desaturation (27.9% [19/68], vs. 14.9% [25/168], P = 0.020). After adjustment of confounders, multivariable analysis showed that muscular desaturation at quadriceps was significantly associated with an increased risk of AKI (OR = 2.84, 95% CI 1.21-6.67, P = 0.016). Muscular desaturations at left and right flank were also associated with an increased risk of AKI (OR = 6.38, 95% CI 1.78-22.89, P = 0.004; OR = 8.90, 95% CI 1.42-45.63; P = 0.019, respectively). Furthermore, patients with muscular desaturation may have a higher risk of pulmonary complications, sepsis and stroke at 30-day follow-up. CONCLUSION: Muscular desaturation was associated with postoperative AKI in older patients undergoing major abdominal surgery which may serve as a predictor of AKI.

Nutritional assessment by ultrasound of the rectus femoris and preperitoneal adipose tissue as predictors of hospitalized patient complications.

INTRODUCTION: Malnutrition and sarcopenia are associated with increased risk of adverse events and worse outcome in hospitalised patients. Ultrasonography is a useful tool in the assessment of body composition. PATIENTS AND METHODS: Twenty-three patients admitted to a hospital ward were recruited. Ultrasonographic variables of muscle tissue and adipose tissue were collected, as well as their variation during admission. These were correlated with anthropometric, clinical and analytical data. RESULTS: We observed a correlation of ultrasound measurements with length of hospitalisation (maximum preperitoneal fat -0.585, rectus femoris thickness - RF -0.539, RF area -0.540), frailty (RF -0.599) and dependency (RF 0.628). RF contractile capacity correlated with reported weekly exercise (0.642). CONCLUSION: RF and preperitoneal fat thickness correlate with the number of days of admission and functional capacity, emerging as prognostic variables.

Bone Tissue Engineering in Rat Calvarial Defects Using Induced Bone-like Tissue by rhBMPs from Immature Muscular Tissues In Vitro.

This study aimed to induce bone-like tissue from immature muscular tissue (IMT) in vitro using commercially available recombinant human bone morphogenetic protein (rhBMP)-2, rhBMP-4, and rhBMP-7, and then implanting this tissue into a calvarial defect in rats to assess healing. IMTs were extracted from 20-day-old Sprague-Dawley (SD) fetal rats, placed on expanded polytetrafluoroethylene (ePTFE) with 10 ng/µL each of rhBMP-2, BMP-4, and BMP-7, and cultured for two weeks. The specimens were implanted into calvarial defects in 3-week-old SD rats for up to three weeks. Relatively strong radiopacity was observed on micro-CT two weeks after culture, and bone-like tissue, comprising osteoblastic cells and osteoids, was partially observed by H&E staining. Calcium, phosphorus, and oxygen were detected in the extracellular matrix using an electron probe micro analyzer, and X-ray diffraction patterns and Fourier transform infrared spectroscopy spectra of the specimen were found to have typical apatite crystal peaks and spectra, respectively. Furthermore, partial strong radiopacity and ossification were confirmed one week after implantation, and a dominant novel bone was observed after two weeks in the defect site. Thus, rhBMP-2, BMP-4, and BMP-7 differentiated IMT into bone-like tissue in vitro, and this induced bone-like tissue has ossification potential and promotes the healing of calvarial defects. Our results suggest that IMT is an effective tissue source for bone tissue engineering.

The dynamics of changes in biochemical markers of the state of tissue in intercostal muscles during the early postmortem period.

AIM: The aim of study was to evaluate structural and biochemical changes in the tissue of intercostal muscles during the early postmortem period (PMP) - 3-13 hours. MATERIALS AND METHODS: Absolute and relative values of the concentration of glycogen, acid phosphatase, lactate, lactate degydrogenase, lipofuscin and cholinesterase during the early PMP were determined on 30 human corpses by results of study of the tissue of intercostal muscles. RESULTS: It was proved that the early PMP was characterized by proper biochemical and biophysical changes of the muscular tissue, the most demonstrative of them were as follows: a reduction in the concentration of glycogen and dynamic increases in the concentrations of lactate dehydrogenase and lipofuscin. For all six biochemical markers, representative absolute and relative values of their popstmortem content in homogenates of intercostal muscles depending upon the prescription of death coming were obtained. It was found out that the concentration of glycogen during the analysed time intervals ranged from (7.821±0.0649) mg/g in 3 hours after death coning to (3.204±0.030) mg/g in 13 hours after the coming of death, reliably (p<0.001) differing every 2 hours of PMP. The dynamics in the concentration of lactate were found to be demonstrative and characterized by its progressive (p<0.01) increase within the period of 9 hours from the moment of death coming: from (6.847±0.042) mmol/g after 3 hours to (12.960±0.085) mmol/g after 9 hours. The level of lipofuscin concentration in the analysed time intervals progressively rose too: from (2.258±0.031) U/g in 3 hours to (5.589±0.030) U/g in 13 hours, reliably (p<0.001) differing every 2 hours of PMP. CONCLUSIONS: Paired correlative indices between biochemical and biophysical markers of the state of tissue of intercostal muscles were examined in their systemic relationships and proper system-creating coefficients were determined by six time intervals of the early PMP, in its turn making it possible to substantiate those of them that were criterially significant for increasing the accuracy of diagnosis of prescription of death coming.

Study of structural and biochemical changes in the muscular tissue of the oesophagus for solving the problem of diagnosing the prescription of death coming.

The modern practice and tactics of forensic medical diagnosis require scientific substantiation of informative diagnostic criteria for assessing the prescription of death coming (PDC), first of all during the early postmortem period (PMP). AIM: The aim of the study was an evaluation of the concentration changes of biochemical markers (BCM) in muscular tissue (MT) of the oesophagus during the early postmortem period. MATERIALS AND METHODS: MT of the oesophagus within the period of 3-13 hours after the coming of death was studied on 30 human corpses. MT was taken with use of special instruments, MT homogenates were prepared following the standard technique with subsequent determination of BCM content in MT homogenates by the kinetic method using for this purpose test systems. RESULTS: Absolute and relative values of the concentrations of glycogen, acid phosphatase, lactate, lactate dehydrogenase, lipofuscin and cholinesterase in MT of the oesophagus in the early PMP (3-13 hours) were determined in 30 human corpses by results of study of the above tissue during different time intervals of the early PMP. Tendencies and regularities in the dynamics of these BCM of the state of the oesophagus were determined by relative values (beginning from 3 hours after the moment of death coming). It is proved that in the interval of 3-5 hours after the coming of death the content of lipofuscin increases by 16.0%, while the concentration of cholinesterase and glycogen decreases by 9.0%, and later - till 9 hours after death coming - these BCM concentrations continue to change according to the above regularities. But in 9 hours after the moment of death coming, side by side with a further decrease in the concentration of glycogen and cholinesterase by 41%, the content of lipofuscin goes on increasing by 57.0%, while the dynamics of changes in the concentration of acid phosphatase are not the same (they decrease). CONCLUSIONS: Absolute and relative values of the concentration of glycogen, acid phosphatase, lactate, lactate dehydrogenase, lipofuscin and cholinesterase in MT of the human oesophagus during different time intervals of the early PMP were determined. Tendencies and regularities in the dynamics of changes in BCM of the state of the oesophagus were determined by relative values. It is proved that determinations of such relationships as lipofuscin/glycogen or lipofuscin/cholinesterase within the terms of 9 hours after the moment of death coming are diagnostically significant (and of equal worth).

Liquid Crystal-Induced Myoblast Alignment.

The ability to control cell alignment represents a fundamental requirement toward the production of tissue in vitro but also to create biohybrid materials presenting the functional properties of human organs. However, cell cultures on standard commercial supports do not provide a selective control on the cell organization morphology, and different techniques, such as the use of patterned or stimulated substrates, are developed to induce cellular alignment. In this work, a new approach toward in vitro muscular tissue morphogenesis is presented exploiting liquid crystalline networks. By using smooth polymeric films with planar homogeneous alignment, a certain degree of cellular order is observed in myoblast cultures with direction of higher cell alignment corresponding to the nematic director. The molecular organization inside the polymer determines such effects since no cell organization is observed using homeotropic or isotropic samples. These findings represent the first example of cellular alignment induced by the interaction with a nematic polymeric scaffold, setting the stage for new applications of liquid crystal polymers as active matter to control tissue growth.

Muscular tissue oxygen saturation during robotic hysterectomy and postoperative nausea and vomiting: exploring the potential therapeutic thresholds.

The relationship between muscular tissue oxygen saturation (SmtO2) during surgery and postoperative nausea and vomiting (PONV) remains to be determined. Patients undergoing robotic hysterectomy participated in this prospective cohort study. SmtO2 of the brachioradialis muscle in the forearm was continuously monitored during surgery. Thresholds based on relative changes or absolute values were systematically assigned. The relationship between thresholds and PONV was investigated based on threshold analysis (i.e., exceeding or not exceeding a threshold), area under the curve analysis (i.e., the size of the area enclosed by the SmtO2 trace and threshold), and multivariable analysis by accounting for recognized PONV risk factors. PONV occurred in 35 of 106 patients (33%). Based on the multivariable analysis, the SmtO2 threshold of 20% above baseline correlated with less PONV (OR 0.39; 95% CI 0.16-0.93; p = 0.034), and the following values correlated with more PONV: 5% below baseline (OR 2.37; 95% CI 1.26-4.45; p = 0.007), 20% below baseline (OR 16.08; 95% CI 3.05-84.73; p = 0.001), < 70% (OR 2.86; 95% CI 1.17-6.99; p = 0.021) and < 60% (OR 6.55; 95% CI 1.11-38.53; p = 0.038). Our study suggests that a potential therapeutic goal for PONV prophylaxis may be to maintain SmtO2 at > 70% and above baseline.

Neomyogenesis in 3D Dynamic Responsive Prosthesis for Inguinal Hernia Repair.

Despite undisputed improvements, prosthetics hernia repair continues to be affected by unacceptable rates of complications. Postoperative adverse events such as discomfort and chronic pain represent a subject of increasing concern among the surgical community. Poor quality biologic response, stiff scar plates, and mesh shrinkage, a typical effect of conventional static meshes and plugs, are all indicated as the main reasons for many of the complications related to inguinal hernia repair. Even the conventional concept of treatment based upon a supposed reinforcement of the groin consequent to the fibrotic incorporation of meshes, would appear to be inadequate in the light of the latest scientific evidence concerning the degenerative genesis of inguinal hernia. Following these recent studies, a newly conceived 3D dynamically responsive implant has been developed. It concerns a multilamellar shaped prosthesis, intended to be placed fixation-free to obliterate the hernia defect. This 3D structure has already demonstrated to induce a probiotic biological response with development of viable tissue, instead of the fibrotic plaque typical of conventional meshes. Newly formed elastic fibers, neo-angiogenesis, and neo-nerve genesis in a surrounding of well perfused connective tissue are the typical elements of the biologic response in the newly conceived implant. In addition to these elements, muscle fibers have also been detected in the implant structure. The aim of this research was to determine the ingrowth of muscle fibers in the implant by assessing the quantity and quality of muscle development in the short, medium, and long term post-implantation. Histological examination of biopsy samples excised from patients who underwent dynamic hernia repair with the 3D dynamic implant showed the presence of muscular elements that in the short term could be described as multiple spots of myocytes in the early stage of development. Over the mid- to long-term, muscle fibers increased in number and level of maturation, assuming the typical aspect of standard muscle bundles in the final phase. Effectively, long term, myocytes histologically evidenced the distinctive arrangement of the muscle structure, with nuclei and striated elements being similar to normal muscle elements. The development of this highly specialized connective tissue in the 3D dynamic responsive implant seems to document the finalization of an enhanced biologic response leading to the ingrowth of typical tissue components of the groin. Reverting degenerative pathogenesis into effective regeneration recognized in the newly conceived 3D prosthesis would appear to represent a significant concept change in the repair of inguinal hernias.

Characteristic properties of muscular-derived extracellular matrix and its application in rat abdominal wall defects.

AIM: To investigate the behavior of porcine-derived decellularized muscular matrix (DMM) in vitro and compare the performance of this biological mesh with that of acellular dermal matrix from pig in a full abdominal wall defect model. MATERIALS & METHODS: To describe the in vitro properties of the DMM scaffold with extracellular matrix histological analysis, growth factor quantification and scanning electron microscopy analysis. To compare structural and functional remodeling between acellular dermal matrix and DMM implants in a rodent full abdominal wall defect model. RESULTS & CONCLUSION: The results demonstrated that cellular components were effectively removed in the DMM scaffold, which also maintained a 3D architecture, biochemical components and strong mechanical properties. In vivo experiments confirm that the DMM mesh could promote remodeling and reconstruction of functional skeletal muscle tissue.

Some Peculiarities of Local Distribution of Multipotent Mesenchymal Stromal Cells after Their Injection into Intact Muscle Tissue in Experiment.

Changes in the muscular tissue after subcutaneous injection of autologous bone marrow multipotent mesenchymal stromal cells transfected with GFP gene and additionally stained with cell membrane dye Vybrant CM-Dil in the projection of ligated femoral vein were studied by light microscopy with luminescence. Stromal cells injected through the skin can appear not only in the damaged tissue where acceleration of regeneration processes is required, but also in intact structures located in superficial or deeper layers. In intact muscular tissue, stromal cells spreading in the perivascular tissue initiate inflammation and migration of macrophages, activate and even trigger sclerotic processes due to differentiation into connective tissue cells (fibroblasts) and stimulation of proliferation and collagen synthesis by host fibroblasts. Injected multipotent mesenchymal stromal cells are gradually phagocytized by macrophages.

Immature muscular tissue differentiation into bone-like tissue by bone morphogenetic proteins in vitro, with ossification potential in vivo.

The objective of this study was to induce bone formation from immature muscular tissue (IMT) in vitro, using bone morphogenetic proteins (BMPs) as a cytokine source and an expanded polytetrafluoroethylene (ePTFE) scaffold. In addition, cultured IMTs were implanted subcutaneously into Sprague-Dawley (SD) rats to determine their in vivo ossification potential. BMPs, extracted from bovine cortical bones, were applied to embryonic SD rat IMT cultures, before 2 weeks culture on ePTFE scaffolds. Osteoblast-like cells and osteoid tissues were partially identified by hematoxylin-eosin staining 2 weeks after culture. Collagen type I (Col-I), osteopontin (OP), and osteocalcin (OC) were detected in the osteoid tissues by immunohistochemical staining. OC gene expression remained low, but OP and Col-I were upregulated during the culture period. In vivo implanted IMTs showed slight radiopacity 1 week after implantation and strong radiopacity 2 and 3 weeks after implantation. One week after implantation, migration of numerous capillaries was observed and ossification was detected after 2 weeks by histological observation. These results suggest that IMTs are able to differentiate into bone-like tissue in vitro, with an ossification potential after implantation in vivo.

Efeito histológico causado na parede posterior da cavidade abdominal pela lavagem com solução salina 0,9% aquecida a diferentes temperaturas: estudo experimental em ratos

The washes of the abdominal cavity with 0,9% salt solution is a very common procedure in General Surgery. In general it doesn't exist an adequate temperature control, being sometimes introduced in the abdominal cavity the saline solution at high temperature, which may possibly cause cell injury. The aim of this work is to study the posterior wall abdominal cavity cell of mice, after it is treated with 0,9% salt solution heated at different degrees. We used 28 mice divided into 3 groups with 9 animals in each group and one as the control mouse. The group A was treated with 0,9% salt solution at 37ºC, the group B at 45ºC and group C at 60ºC. The control mouse wasn't treated with 0,9% salt solution. In all groups the 0,9% salt solution stayed in the abdominal cavity for 1 minute. Histopatologic exam revealed in the control mouse and group A and B the muscle fibers and cellular estriations was intact. In the group C, meanwhile observed principles of cellular degeneration. Concluding the importance of effective temperature control of 0,9% salt solution to be introduce in mice abdominal cavity must be emphasized to prevent thermal injury in cells.

A lavagem da cavidade abdominal com solução salina 0,9% aquecida é uma prática comum em cirurgia geral, mas, geralmente, não há um controle adequado da sua temperatura, sendo por vezes introduzida na cavidade abdominal a temperaturas elevadas, possivelmente causando lesões no nível celular. O objetivo do trabalho é estudar a célula da parede posterior da cavidade abdominal de ratos após o tratamento desta com solução salina 0,9% aquecida a graus diversos. Foram utilizados 28 ratos divididos em três grupos com 9 animais cada e um rato controle. O grupo A foi tratado com solução salina 0,9% a 37ºC, o grupo B a 45ºC e o grupo C a 60ºC. O rato controle não recebeu tratamento com solução salina 09,%. Em todos os grupos a solução salina 0,9% permaneceu na cavidade durante 1 minuto. Exame histopatológico revelou que no rato controle e nos grupos A e B as fibras musculares e as estriações celulares estavam intactas. No grupo C, no entanto, observaram-se princípios de degeneração celular. Como conclusão ressalta-se a importância de um controle efetivo da temperatura da solução salina 0,9% a ser introduzida na cavidade abdominal de ratos para prevenir um trauma térmico no nível celular.