In vivo thermal conductivity of the human forearm tissues

1991 ◽  
Vol 70 (6) ◽  
pp. 2682-2690 ◽  
Author(s):  
M. B. Ducharme ◽  
P. Tikuisis
Keyword(s):  
Longitudinal Axis ◽  
Skin Surface ◽  
Tissue Temperature ◽  
Bioheat Equation ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Computed Tomography Scanning ◽  
Human Forearm

The effective thermal conductivities of the skin + subcutaneous (keff skin + fat) and muscle (keff muscle) tissues of the human forearm at thermal steady state during immersion in water at temperatures (Tw) ranging from 15 to 36 degrees C were determined. Tissue temperature (Tt) was continuously monitored by a calibrated multicouple probe during a 3-h immersion of the resting forearm. Tt was measured every 5 mm from the longitudinal axis of the forearm (determined from computed-tomography scanning) to the skin surface. Skin temperature (Tsk), heat loss (Hsk), and blood flow (Q) of the forearm, as well as rectal temperature (Tre) and arterial blood temperature at the brachial artery (Tbla), were measured during the experiments. When the keff values were calculated from the finite-element (FE) solution of the bioheat equation, keff skin + fat ranged from 0.28 +/- 0.03 to 0.73 +/- 0.14 W.degrees C-1.m-1 and keff muscle varied between 0.56 +/- 0.05 and 1.91 +/- 0.19 W.degrees C-1.m-1 from 15 to 36 degrees C. The values of keff skin + fat and keff muscle, calculated from the FE solution for Tw less than or equal to 30 degrees C, were not different from the average in vitro values obtained from the literature. The keff values of the forearm tissues were linearly related (r = 0.80, P less than 0.001) to Q for Tw greater than or equal to 30 degrees C. It was found that the muscle tissue could account for 92 +/- 1% of the total forearm insulation during immersion in water between 15 and 36 degrees C.

Tissue temperature profile in the human forearm during thermal stress at thermal stability

1991 ◽  
Vol 71 (5) ◽  
pp. 1973-1978 ◽  
Author(s):  
M. B. Ducharme ◽  
W. P. VanHelder ◽  
M. W. Radomski
Keyword(s):  
Thermal Stability ◽  
Thermal Stress ◽  
Temperature Profile ◽  
Radial Distance ◽  
Longitudinal Axis ◽  
The Body ◽  
Tissue Temperature ◽  
Experimental Conditions ◽  
Computed Tomography Scanning ◽  
Human Forearm

The purpose of the present study was to investigate the effect of a range of water temperatures (Tw from 15 to 36 degrees C) on the tissue temperature profile of the resting human forearm at thermal stability. Tissue temperature (Tti) was continuously monitored by a calibrated multicouple probe during 3 h of immersion of the forearm. The probe was implanted approximately 9 cm distal from the olecranon process along the ulnar ridge. Tti was measured every 5 mm, from the longitudinal axis of the forearm (determined from computed tomography scanning) to the skin surface. Along with Tti, skin temperature (Tsk), rectal temperature (Tre), and blood flow were measured during the immersions. For all temperature conditions, the temperature profile inside the limb was linear as a function of the radial distance from the forearm axis (P less than 0.001). Temperature gradient measured in the forearm ranged from 0.2 +/- 0.1 degrees C C cm (Tw = 36 degrees C) to 2.3 +/- 0.5 degrees C cm (Tw = 15 degrees C). The maximal Tti was measured in all cases at the longitudinal axis of the forearm and was in all experimental conditions lower than Tre. On immersion at Tw less than 36 degrees C, the whole forearm can be considered to be part of the shell of the body. With these experimental data, mathematical equations were developed to predict, with an accuracy of at least 0.6 degrees C, the Tti at any depth inside the forearm at steady state during thermal stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular Effects of Micromeria graeca (L.) Benth. ex Rchb in Normotensive and Hypertensive Rats

2020 ◽  
Vol 20 (8) ◽  
pp. 1253-1261
Author(s):  
Mourad Akdad ◽  
Mohamed Eddouks
Keyword(s):  
Blood Pressure ◽  
Cardiovascular System ◽  
Arterial Blood Pressure ◽  
Antihypertensive Activity ◽  
Computer Assisted ◽  
Hypertensive Rats ◽  
Vasorelaxant Effect ◽  
Arterial Blood

Aims: The present study was performed in order to analyze the antihypertensive activity of Micromeria graeca (L.) Benth. ex Rchb. Background: Micromeria graeca (L.) Benth. ex Rchb is an aromatic and medicinal plant belonging to the Lamiaceae family. This herb is used to treat various pathologies such as cardiovascular disorders. Meanwhile, its pharmacological effects on the cardiovascular system have not been studied. Objective: The present study aimed to evaluate the effect of aqueous extract of aerial parts of Micromeria graeca (AEMG) on the cardiovascular system in normotensive and hypertensive rats. Methods: In this study, the cardiovascular effect of AEMG was evaluated using in vivo and in vitro investigations. In order to assess the acute effect of AEMG on the cardiovascular system, anesthetized L-NAME-hypertensive and normotensive rats received AEMG (100 mg/kg) orally and arterial blood pressure parameters were monitored during six hours. In the sub-chronic study, rats were orally treated for one week, followed by blood pressure assessment during one week of treatment. Blood pressure was measured using a tail-cuff and a computer-assisted monitoring device. In the second experiment, isolated rat aortic ring pre-contracted with Epinephrine (EP) or KCl was used to assess the vasorelaxant effect of AEMG. Results: Oral administration of AEMG (100 mg/kg) provoked a decrease of arterial blood pressure parameters in hypertensive rats. In addition, AEMG induced a vasorelaxant effect in thoracic aortic rings pre-contracted with EP (10 μM) or KCl (80 mM). This effect was attenuated in the presence of propranolol and methylene blue. While in the presence of glibenclamide, L-NAME, nifedipine or Indomethacin, the vasorelaxant effect was not affected. Conclusion: This study showed that Micromeria graeca possesses a potent antihypertensive effect and relaxes the vascular smooth muscle through β-adrenergic and cGMP pathways.

Vasorelaxant and Antihypertensive Effects of Mentha pulegium L. in Rats: An in vitro and in vivo Approach

2020 ◽  
Vol 20 ◽  
Author(s):  
Mohammed Ajebli ◽  
Mohamed Eddouks
Keyword(s):  
Blood Pressure ◽  
Acute Experiment ◽  
Antihypertensive Activity ◽  
Mentha Pulegium ◽  
In Vitro Experiment ◽  
Arterial Blood ◽  
Dose Dependent ◽  
Ca2 Channels

Aims and objective: The aim of the study was to investigate the effect of aqueous aerial part extract of Mentha pulegium L. (Pennyrile) (MPAE) on arterial pressure parameters in rats. Background: Mentha pulegium is a medicinal plant used to treat hypertension in Morocco. Material and methods: In the current study, MPAE was prepared and its antihypertensive activity was pharmacologically investigated. L-NAME-hypertensive and normotensive rats have received orally MPAE (180 and 300 mg/kg) during six hours for the acute experiment and during seven days for the sub-chronic treatment. Thereafter, systolic, diastolic, mean arterial blood pressure and heart rate were evaluated. While, in the in vitro experiment, isolated denuded and intact thoracic aortic rings were suspended in a tissue bath system and the tension changes were recorded. Results: A fall in blood pressure was observed in L-NAME-induced hypertensive treated with MPAE. The extract also produced a dose-dependent relaxation of aorta pre-contracted with NE and KCl. The study showed that the vasorelaxant ability of MPAE seems to be exerted through the blockage of extracellular Ca2+ entry. Conclusion: The results demonstrate that the extract of pennyrile exhibits antihypertensive activity. In addition, the effect may be, at least in part, due to dilation of blood vessels via blockage of Ca2+ channels.

Investigation of the Thermal and Injury Behavior During Microwave Thermal Therapy of Porcine Kidney

2002 ◽  
Author(s):  
Xiaoming He ◽  
Shawn Mcgee ◽  
James E. Coad ◽  
Paul A. Iaizzo ◽  
David J. Swanlund ◽  
...  
Keyword(s):  
Thermal Model ◽  
Histological Study ◽  
Kidney Cortex ◽  
Cellular Injury ◽  
Bioheat Equation ◽  
Tissue Slices ◽  
Thermal Histories ◽  
Microwave Probe

In this paper, we report on the characterization of microwave therapy of normal porcine kidneys both in vitro and in vivo. This technology is being developed for eventual use in the treatment of small renal cell carcinoma (RCC) by minimally invasive procedures. During experiments, microwave energy was applied through an interstitial microwave probe (Urologix, Plymouth, MN) to the kidney cortex with occasional involvement of the kidney medulla. The thermal histories at several locations were recorded. After treatment, the kidneys were bisected and small tissue slices were cut out at approximately the same depth as the thermal probes. The tissue slices were further processed for histological study. Both cellular injury and the area of microvascular stasis were quantitatively evaluated by histology. Absolute rate kinetic models of cellular injury and vascular stasis were developed and fit to this data. A 3-D finite element thermal model based on the Pennes Bioheat equation was developed and solved using a commercial software package (ANSYS, V5.7). The Specific Absorption Rate (SAR) of the microwave probe was measured experimentally in tissue equivalent gel-like solution. The thermal model was first validated by the measured in vitro thermal histories. It was then used to determine the blood perfusion term in vivo.

scholarly journals Is the resting rate of oxygen consumption of locomotor muscles in crustaceans limited by the low blood oxygenation strategy?

2001 ◽  
Vol 204 (5) ◽  
pp. 933-940 ◽  
Author(s):  
J. Forgue ◽  
A. Legeay ◽  
J.C. Massabuau
Keyword(s):  
Blood Oxygenation ◽  
Whole Body ◽  
Blood Gas ◽  
Astacus Leptodactylus ◽  
Night Time ◽  
Arterial Blood ◽  
Rate Of Oxygen Consumption ◽  
Locomotor Muscles

Numerous water-breathers exhibit a gas-exchange regulation strategy that maintains O(2) partial pressure, P(O2), in the arterial blood within the range 1–3 kPa at rest during the daytime. In a night-active crustacean, we examined whether this could limit the rate of O(2)consumption (M(O2)) of locomotor muscles and/or the whole body as part of a coordinated response to energy conservation. In the crayfish Astacus leptodactylus, we compared the in vitro relationship between the M(O2) of locomotor muscles as a function of the extracellular P(O2) and P(CO2) and in vivo circadian changes in blood gas tensions at various values of water P(O2). In vitro, the M(O2) of locomotor muscle, either at rest or when stimulated with CCCP, was O(2)-dependent up to an extracellular P(O2) of 8–10 kPa. In vivo, the existence of a night-time increase in arterial P(O2) of up to 4 kPa at water P(O2) values of 20 and 40 kPa was demonstrated, but an experimental increase in arterial P(O2) during the day did not lead to any rise in whole-body M(O2). This suggested that the low blood P(O2) in normoxia has no global limiting effect on daytime whole-body M(O2). The participation of blood O(2) status in shaping the circadian behaviour of crayfish is discussed.

In vivo characterization of vasocontractile activities in erythrocytes

1983 ◽  
Vol 58 (3) ◽  
pp. 356-361 ◽  
Author(s):  
Michael P. McIlhany ◽  
Lydia M. Johns ◽  
Thomas Leipzig ◽  
Nicholas J. Patronas ◽  
Frederick D. Brown ◽  
...  
Keyword(s):  
Vascular Resistance ◽  
Peripheral Resistance ◽  
Content Type ◽  
Control Value ◽  
Arterial Blood ◽  
Anesthetized Dogs ◽  
Chronic Cerebral Vasospasm ◽  
In Vivo Characterization

✓ Partially purified protein from washed and artificially hemolyzed erythrocytes, known to cause significant contractions of isolated canine cerebral vessels in vitro, was injected into the cisterna magna of intact anesthetized dogs. Cerebral blood flow, measured by the xenon-133 washout technique, decreased from a control value of 49.5 ± 1.17 ml/100 gm/min to an experimental value of 34.1 ± 1.65 ml/100 gm/min at 2 hours. Cerebral vascular resistance rose from a control value of 2.05 ± 0.17 PRU (peripheral resistance units) to an experimental value of 2.91 ± 0.25 PRU at 2 hours. Mean arterial blood pressure, heart rate, intracranial pressure, and cerebral perfusion pressure remained stable. Cardiac output also fell significantly (in 2-hour control animals it was 2.89 ± 0.37 liter/min, and in 2-hour experimental animals 1.43 ± 0.13 liter/min) and peripheral vascular resistance rose. These changes were evident by 10 minutes after the cisternal injection of the hemolysate protein, and remained for the duration of the 2-hour monitoring period. Serial vertebrobasilar angiograms demonstrated marked narrowing of the intracranial basilar artery when compared to control values. The narrowing persisted for several days in most animals, and tended to increase with time. Relaxation occurred by the 10th through the 14th day. The authors conclude that this experimental preparation may be a useful model for both in vitro and in vivo investigation of chronic cerebral vasospasm.

Amentoflavone Inhibits Osteoclastogenesis and Wear Debris-Induced Osteolysis via Suppressing NF-κB and MAPKs Signaling Pathways

Planta Medica ◽  
2018 ◽  
Vol 84 (11) ◽  
pp. 759-767 ◽  
Author(s):  
Zhen Zhang ◽  
Shuai Zhao ◽  
Xiaolei Li ◽  
Xiaoqi Zhuo ◽  
Wu Zhang ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Aseptic Loosening ◽  
Wear Debris ◽  
Mitogen Activated Protein Kinase ◽  
Micro Computed Tomography ◽  
Computed Tomography Scanning ◽  
Mitogen Activated Protein ◽  
And Function

AbstractWear debris-induced osteolysis is one of the major reasons for subsequent aseptic loosening after cementless hip arthroplasty. Increasing evidence suggests that receptor activator of nuclear factor kappa-B (NF-κB) ligand-mediated osteoclastogenesis and osteolysis are responsible for wear debris-induced aseptic loosening. In the present study, we explored the effect of amentoflavone (AMF) on inhibiting osteoclast generation and wear debris-induced osteolysis in vitro and in vivo. Twenty-four male C57BL/J6 mice were randomly divided into four groups: a sham group and groups with titanium wear debris treatment followed by intraperitoneal injection of various concentrations of AMF (0, 20, and 40 mg/kg/day). The micro computed tomography scanning and histological analysis were performed. Bone marrow-derived macrophages were cultured to investigate the effect of AMF on osteoclast generation and function. The results showed that AMF suppressed osteoclastogenesis, F-actin ring formation, and bone absorption without cytotoxicity. AMF prevented titanium wear debris-induced osteolysis in mice. AMF suppressed the relative proteins of NF-κB and mitogen-activated protein kinase (MAPKs) signaling pathways. Thus, the present study suggests that AMF derived from plants could inhibit osteoclastogenesis and titanium wear debris-induced osteolysis via suppressing NF-κB and MAPKs signaling pathways.

Acoustic Signals from Skeletal Muscle

Physiology ◽  
1990 ◽  
Vol 5 (1) ◽  
pp. 17-21 ◽  
Author(s):  
DT Barry
Keyword(s):  
Skeletal Muscles ◽  
Acoustic Signals ◽  
Skin Surface ◽  
Pressure Waves ◽  
Mechanical Vibrations ◽  
Intrinsic Component ◽  
Measuring Force ◽  
Muscle Sounds

Contracting skeletal muscles emit pressure waves that are audible at the skin surface and are easily recorded with standard microphones both in vivo and in vitro. These muscle sounds are an intrinsic component of the contractile mechanism and are produced by mechanical vibrations at the resonant frequency of the muscle. The sounds are useful in measuring force, fatigue, and mechanical properties of muscle.

scholarly journals Angiotensin II infusion in vivo does not modulate cortisol secretion in the late-gestation ovine fetus

1998 ◽  
Vol 275 (2) ◽  
pp. R357-R362 ◽  
Author(s):  
Kirsten R. Poore ◽  
I. Ross Young ◽  
Benedict J. Canny ◽  
Geoffrey D. Thorburn
Keyword(s):  
Angiotensin Ii ◽  
Adrenal Gland ◽  
Late Gestation ◽  
Treatment Groups ◽  
Arterial Blood ◽  
Basal Cortisol ◽  
Ovine Fetus

Maturation of the fetal adrenal gland is critical for the onset of ovine parturition. It has long been proposed that the fetal adrenal gland may be under inhibitory influences during late gestation. In vitro evidence has suggested that angiotensin II may be such an inhibitory factor and may help to prevent a premature increase in cortisol concentrations. The aim of this study was to test the effect of angiotensin II infusion in vivo on basal cortisol concentrations and fetal adrenal responsiveness to an ACTH-(1—24) challenge. Fetuses received a continuous infusion of either angiotensin II (100 ng ⋅ min−1 ⋅ kg−1; n = 7) or saline (2 ml/h; n = 4), which commenced at 140 days of gestation (GA) and continued for a total of 50 h. Adrenal responsiveness to the administration of ACTH-(1—24) (5 μg/kg) was determined during angiotensin II or saline infusions at both 2 and 48 h after infusion onset. Angiotensin II had no significant effect on adrenal responsiveness after acute (2 h) or chronic (48 h) infusion. There was no effect of saline or angiotensin II infusion on basal immunoreactive ACTH or cortisol concentrations after 2 h, but there was a significant increase in basal cortisol concentrations in both treatment groups by 48 h, probably reflecting the normal rise in cortisol concentrations at this GA. Mean arterial blood pressure was significantly increased in angiotensin II-infused fetuses only. This study has therefore found no evidence to suggest that angiotensin II infusion in vivo modulates fetal basal cortisol concentrations or adrenal responsiveness in the last week of gestation, in contrast with previous in vitro studies. These results throw into question the proposed role of angiotensin II as a negative modulator of adrenal function in the ovine fetus.

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

Ultrasound ◽  
2020 ◽  
pp. 1742271X2095319
Author(s):  
Stephanie F Smith ◽  
Piero Miloro ◽  
Richard Axell ◽  
Gail ter Haar ◽  
Christoph Lees
Keyword(s):  
Temperature Increase ◽  
Skin Surface ◽  
Maximum Temperature ◽  
Factors Affecting ◽  
Bone Interface ◽  
Heating Effects ◽  
Power Setting ◽  
Lower Temperature

Introduction The quantification of heating effects during exposure to ultrasound is usually based on laboratory experiments in water and is assessed using extrapolated parameters such as the thermal index. In our study, we have measured the temperature increase directly in a simulator of the maternal–fetal environment, the ‘ISUOG Phantom’, using clinically relevant ultrasound scanners, transducers and exposure conditions. Methods The study was carried out using an instrumented phantom designed to represent the pregnant maternal abdomen and which enabled temperature recordings at positions in tissue mimics which represented the skin surface, sub-surface, amniotic fluid and fetal bone interface. We tested four different transducers on a commercial diagnostic scanner. The effects of scan duration, presence of a circulating fluid, pre-set and power were recorded. Results The highest temperature increase was always at the transducer–skin interface, where temperature increases between 1.4°C and 9.5°C were observed; lower temperature rises, between 0.1°C and 1.0°C, were observed deeper in tissue and at the bone interface. Doppler modes generated the highest temperature increases. Most of the heating occurred in the first 3 minutes of exposure, with the presence of a circulating fluid having a limited effect. The power setting affected the maximum temperature increase proportionally, with peak temperature increasing from 4.3°C to 6.7°C when power was increased from 63% to 100%. Conclusions Although this phantom provides a crude mimic of the in vivo conditions, the overall results showed good repeatability and agreement with previously published experiments. All studies showed that the temperature rises observed fell within the recommendations of international regulatory bodies. However, it is important that the operator should be aware of factors affecting the temperature increase.

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