Influence Of Body Temperature Research Articles

The role of gamma globulin, complement component 1q, factor B, properdin, body temperature, C-reactive protein and serum amyloid alpha to the activity and the function of the human complement system and its pathways

The complement system plays a crucial role in orchestrating the activation and regulation of inflammation within the human immune system. Three distinct activation pathways—classical, lectin, and alternative—converge to form the common lytic pathway, culminating in the formation of the membrane-attacking complex that disrupts the structure of pathogens. Dysregulated complement system activity can lead to tissue damage, autoimmune diseases, or immune deficiencies.In this study, the antimicrobial activity of human serum was investigated by using a bioluminescent microbe probe, Escherichia coli (pEGFPluxABCDEamp). This probe has previously been used to determine the antimicrobial activity of complement system and the polymorphonuclear neutrophils. In this study, blocking antibodies against key serum activators and components, including IgG, complement component 1q, factor B, and properdin, were utilized. The influence of body temperature and acute phase proteins, such as C reactive protein (CRP) and serum amyloid alpha (SAA), on the complement system was also examined.The study reveals the critical factors influencing complement system activity and pathway function. Alongside crucial factors like C1q and IgG, alternative pathway components factor B and properdin played pivotal roles. Results indicated that the alternative pathway accounted for approximately one third of the overall serum antimicrobial activity, and blocking this pathway disrupted the entire complement system. Contrary to expectations, elevated body temperature during inflammation did not enhance the antimicrobial activity of human serum.CRP demonstrated complement activation properties, but at higher physiological concentrations, it exhibited antagonistic tendencies, dampening the response. On the other hand, SAA enhanced the serum's activity.Overall, this study sheds a light on the critical factors affecting both complement system activity and pathway functionality, emphasizing the importance of a balanced immune response.

Triage body temperature and its influence on patients with acute myocardial infarction

BackgroundFever can occur after acute myocardial infarction (MI). The influence of body temperature (BT) after hospital arrival on patients with acute MI has rarely been investigated.MethodsPatients who were diagnosed with acute MI in the emergency department (ED) of a tertiary teaching hospital between 1 January 2020 and 31 December 2020 were enrolled. Based on the tympanic temperature obtained at the ED triage, patients were categorized into normothermic (35.5°C-37.5°C), hypothermic (< 35.5°C), or hyperthermic (> 37.5°C) groups. The primary outcome was in-hospital cardiac arrest (IHCA), while the secondary outcomes were adverse events. Statistical significance was set at p < 0.05.ResultsThere were 440 enrollees; significant differences were found among the normothermic (n = 369, 83.9%), hypothermic (n = 27, 6.1%), and hyperthermic (n = 44, 10.0%) groups in the triage respiratory rate (median [IQR]) (20.0 [4.0] cycles/min versus 20.0 [4.0] versus 20.0 [7.5], p = 0.009), triage heart rate (88.0 [29.0] beats/min versus 82.0 [28.0] versus 102.5 [30.5], p < 0.001), presence of ST-elevation MI (42.0% versus 66.7% versus 31.8%, p = 0.014), need for cardiac catheterization (87.3% versus 85.2% versus 72.7%, p = 0.034), initial troponin T level (165.9 [565.2] ng/L versus 49.1 [202.0] versus 318.8 [2002.0], p = 0.002), peak troponin T level (343.8 [1405.9] ng/L versus 218.7 [2318.2] versus 832.0 [2640.8], p = 0.003), length of ICU stay (2.0 [3.0] days versus 3.0 [8.0] versus 3.0 [9.5], p = 0.006), length of hospital stay (4.0 [4.5] days versus 6.0 [15.0] versus 10.5 [10.8], p < 0.001), and infection during hospitalization (19.8% versus 29.6% versus 63.6%, p < 0.001) but not in IHCA (7.6% versus 14.8% versus 11.4%, p = 0.323) or any adverse events (50.9% versus 48.1% versus 63.6%, p = 0.258). Multivariable analysis showed no significant association of triage BT with IHCA or any major complication.ConclusionTriage BT did not show a significant association with IHCA or adverse events in patients with acute MI. However, triage BT could be associated with different clinical presentations and should warrant further investigation.

Implementation of Gyro Accelerometer Sensor for Measuring Respiration Rate Based on Inhale and Exhale Using Kalman Filter

Respiratory rate is a fundamental vital sign that is sensitive to different pathological conditions including heart, lung, emotional stress, the influence of body temperature and activity fatigue. The respiratory rate in humans is measured by counting the number of breaths for one minute by monitoring and counting the number of times the chest rises and falls during the inhale and exhale process. Various methods for measuring respiratory rate that are commonly used including pneumograph, impedance and capnography are applied in patient monitoring. This study aims to examine and analyze the application of the kalman filter on the output of the gyro accelerometer sensor to increase the results of the detection of respiratory rates using the gyro accelerometer sensor. This study test was carried out using a patient simulator in Surabaya Ministry of Health Polytechnic nursing laboratory. This simulator patient can simulate respiration with a mechanical work system up and down the chest and abdomen, uses an Arduino Nano microcontroller to filter the output of the gyro accelerometer sensor and the results will be compared before and after the filter. The independent variable in this study is the respiration value, while the dependent variable is the sensor output before being filtered. In the relaxed condition of the respondent The most effective use of the kalman filter is found in the parameters R = 10, Q = 0.1 because in the use of these parameters, the value after being filtered has a value that tends to be stable. The highest error value in the application of the gyro accelerometer sensor occurs at sensor position 1 with R = 1 Q = 10 value of 2,6%. This study shows the effect of differences in respiration values before and after using a kalman filter. This study has limited differences in values that are far between the pre filter and after being filtered in several data collections.

Towards a Functional Atraumatic Self‐Shaping Cochlear Implant

Inside Cover: In article number 2100620 by Daniel Bautista-Salinas and co-workers, a cochlear implant (CI) that curls into the cochlea under the influence of body temperature is proposed as an alternative to current CIs which generate intracochlear trauma during implantation. The CI recovery forces are studied numerically and experimentally and results show values below the rupture threshold. A recovery study in a functional CI shows that the device could be used clinically.

Towards a Functional Atraumatic Self‐Shaping Cochlear Implant

AbstractCochlear implants (CIs) have been shown to improve hearing in patients suffering from sensorineural hearing loss. CIs deliver electrical pulses to the hearing nerve via an electrode array that is carefully inserted in the scala tympani in a complex surgical procedure. However, current CIs can cause trauma during insertion, threatening hearing preservation. Existing pre‐curved CIs use external mechanisms to be inserted. In this work, a pre‐curved CI is proposed that curls into the cochlea under the influence of body temperature. By comparison to existing CIs, the proposed device can be smaller and easily inserted. The implant material is implemented in COMSOL to simulate its behavior, and an analytical study is conducted to verify the material model. Two additional studies are carried out to assess the implant recovery forces and their ability to recover shape even with embedded metal. Numerical modeling and experimental tests suggest that the CI recovery forces are below the rupture threshold. The recovery study in a functional self‐shaping CI shows that the device will still be able to curl in the cochlea. This implant concept has thus shown potential to be eventually used in clinical practice and improve hearing outcomes seen at present.

Influence of Body Temperature on Bispectral Index-Guided Anesthetic Management in Off-Pump Coronary Artery Bypass Grafting

Abstract Background Perioperative hypothermia is not uncommon in surgical patients due to anesthetic-induced inhibition of thermoregulatory mechanisms and exposure of patients to cold environment in the operating rooms. Core temperature reduction up to 35°C is often seen in off-pump coronary artery bypass graft (OP-CABG) surgery. Anesthetic depth can be monitored by using bispectral (BIS) index. The present study was performed to evaluate the influence of mild hypothermia on the anesthetic depth using BIS monitoring and correlation of BIS with end-tidal anesthetic concentration at varying temperatures during OP-CABG. Materials and Methods In a prospective observational study design in a tertiary care teaching hospital, patients who underwent elective OP-CABG under endotracheal general anesthesia, were included in the study. Standard technique of anesthesia was followed. BIS, nasopharyngeal temperature, and end-tidal anesthetic concentration of inhaled isoflurane was recorded every 10 minutes. The BIS was adjusted to between 45 and 50 during surgery. Results There were 40 patients who underwent OP-CABG during the study period. The mean age was 51.2 ± 8.7 years, mean body mass index 29.8 ± 2.2, and mean left ventricular ejection fraction was 55.4 ± 4.2%. Anesthetic requirement as guided by BIS between 45 and 50 correlated linearly with core body temperature (r = 0.999; p &lt; 0.001). The mean decrease in the body temperature at the end of 300 minutes was 2.2°C with a mean decrease in end-tidal anesthetic concentration of 0.29%. The reduction in end-tidal anesthetic concentration per degree decrease in temperature was 0.13%. None of the patients reported intraoperative recall. Conclusion In this study, BIS monitoring was used to guide the delivery concentration of inhaled anesthetic using a targeted range of 45 to 50. BIS monitoring allowed the appropriate reduction of anesthetic dosing requirements in patients undergoing OP-CABG without risk of awareness. There was a significant reduction in anesthetic requirements associated with reduction of core temperature. The routine use of BIS is recommended in OP-CABG to titrate anesthetic requirement during occurrence of hypothermia and facilitate fast-track anesthesia in this patient population.

The influence of body temperature on tissue stiffness, blood perfusion, and water diffusion in the mouse brain

While hypothermia of the brain is used to reduce neuronal damage in patients with conditions such as traumatic brain injury or stroke, little is known about how temperature affects the biophysical properties of in vivo brain tissue. Therefore, we measured shear wave speed (SWS), apparent diffusion coefficient (ADC), and cerebral blood flow (CBF) in the mouse brain at different body temperatures to investigate the relationship between temperature and tissue stiffness, water diffusion, and blood perfusion in the living brain. Multifrequency magnetic resonance elastography (MRE), diffusion-weighted imaging (DWI), and arterial spin labeling (ASL) were performed in seven mice while increasing and recording body temperature from hypothermia (28–30 °C) to normothermia (36–38 °C). SWS, ADC, and CBF were analyzed in regions of whole brain, cortex, hippocampus, and diencephalon. Our results show that SWS decreases while ADC and CBF increase from hypothermia to normothermia (whole brain SWS: −6.2%, ADC: +34.0%, CBF: +80.2%; cortex SWS: −10.1%, ADC: +30.9%, CBF: +82.4%; all p > 0.05). We found a significant inverse correlation between SWS and both ADC and CBF in all analyzed regions except diencephalon (whole brain SWS-ADC: r = −0.8, p < 0.005; SWS-CBF: r = −0.84, p < 0.005; cortex SWS-ADC: r = −0.74, p < 0.05; SWS-CBF: r = −0.65, p < 0.05). These results show that in vivo brain stiffness is inversely correlated with temperature, extracellular water mobility, and microvascular blood flow. Regional differences indicate that cortical areas are more markedly affected by hypothermia than central regions such as diencephalon. Temperature should be considered as a confounder in elastographic measurements, especially in preclinical settings. Statement of SignificanceHibernating mammals lower their body temperature and metabolic activity. A hypothermic state can also be induced for medical purposes to reduce the risk of neural damage in patients with neurological disease or injury. However, little is known how physical soft-tissue properties of the in-vivo brain such as water diffusion, blood perfusion or mechanical parameters correlate with each other when temperature changes. Our study demonstrates for the first time that those quantitative imaging markers are tightly linked to changes in body temperature. While water diffusion and blood perfusion are reduced during hypothermia, brain stiffness significantly increases, suggesting that multiparametric quantitative MRI should be used for the noninvasive assessment of brain metabolic activity.

Influence of body temperature in autoregulation measured by cerebral oximetry index need more research

Cerebral autoregulation (CA) is the mechanism responsible for maintaining a relatively constant cerebral blood flow (CBF) over a wide range of arterial blood pressure. CA depends on several mechanisms to maintain a suitable CBF based on cerebral metabolic demands. These mechanisms protect the brain from oligemia or hyperemia. Under specific conditions, the range of CA is severely compromised, increasing the risk of cerebral swelling (1).

Accuracy of the Aspartic Acid Racemization Technique in Age Estimation of Mammals and the Influence of Body Temperature

The aspartic acid racemization (AAR) technique has been applied for age estimation of humans and other mammals for more than four decades. In this study, eye lenses from 124 animals representing 25 mammalian species were collected and D/L ratios obtained using the AAR technique. The animals were either of known age or had the age estimated by other methods. The purpose of the study was to: a) estimate the accuracy of the AAR technique, and b) examine the effect of body temperature on racemization rates. Samples from four of the 25 species covered the range of ages that is needed to estimate species-specific racemization rates. The sample size from a single species of known age, the pygmy goat (Capra hircus, n = 35), was also large enough to investigate the accuracy of ages obtained using the AAR technique. The 35 goats were divided into three datasets: all goats (n = 35), goats &gt;0.5 yrs old (n = 26) and goats &gt;2 yrs old (n = 19). Leave-one-out analyses were performed on the three sets of data. Normalized root mean squared errors for the group of goats &gt;0.5 yrs old were found to be the smallest. The higher variation in D/L measurements found for young goats &lt;0.5 yrs can probably be explained by a period of continued postnatal growth of the eye lens. Normalized root mean squared errors from the leave-one-out cross-validation analyses based on goats &gt;0.5 yrs old was for three age groups of the goats: 0.934 yrs for young goats &lt;2 yrs (n = 16), 0.102 yrs for adult goats from 2–8 yrs (n = 15) and 0.133 yrs for old goats &gt;8 yrs (n = 4). Thus, the age of an adult or an old animal can be predicted with approximately 10% accuracy, whereas the age of a young animal is difficult to predict. A goat specific racemization rate, as a 2kAsp value, was estimated to 0.0107 ± 3.8 x 10-4 SE (n = 26). The 2kAsp values from 12 species, four estimated in this study and another eight published, were used to examine the effect of core body temperature on the rate of racemization. A positive relationship between AAR and temperature was found (r2 = 0.321) but results also suggest that other factors besides temperature are involved in the racemization process in living animals. Based on our results we emphasize that non-species-specific racemization rates should be used with care in AAR age estimation studies and that the period of postnatal growth of the eye lens be considered when estimating species-specific D/L0 values and ages of young individuals.

Body Temperature after EMS Transport: Association with Traumatic Brain Injury Outcomes

Introduction: Low body temperatures following prehospital transport are associated with poor outcomes in patients with traumatic brain injury (TBI). However, a minimal amount is known about potential associations across a range of temperatures obtained immediately after prehospital transport. Furthermore, a minimal amount is known about the influence of body temperature on non-mortality outcomes. The purpose of this study was to assess the correlation between temperatures obtained immediately following prehospital transport and TBI outcomes across the entire range of temperatures. Methods: This retrospective observational study included all moderate/severe TBI cases (CDC Barell Matrix Type 1) in the pre-implementation cohort of the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS: 1R01NS071049). Cases were compared across four cohorts of initial trauma center temperature (ITCT): <35.0°C [Very Low Temperature (VLT)]; 35.0–35.9°C [Low Temperature (LT)]; 36.0–37.9°C [Normal Temperature (NT)]; and ≥38.0°C [Elevated Temperature (ET)]. Multivariable analysis was performed adjusting for injury severity score, age, sex, race, ethnicity, blunt/penetrating trauma, and payment source. Adjusted odds ratios (aORs) with 95% confidence intervals (CI) for mortality were calculated. To evaluate non-mortality outcomes, deaths were excluded and the adjusted median increase in hospital length of stay (LOS), ICU LOS and total hospital charges were calculated for each ITCT group and compared to the NT group. Results: 22,925 cases were identified and cases with interfacility transfer (7361, 32%), no EMS transport (1213, 5%), missing ITCT (2083, 9%), or missing demographic data (391, 2%) were excluded. Within this study cohort the aORs for death (compared to the NT group) were 2.41 (CI: 1.83–3.17) for VLT, 1.62 (CI: 1.37–1.93) for LT, and 1.86 (CI: 1.52–3.00) for ET. Similarly, trauma center (TC) LOS, ICU LOS, and total TC charges increased in all temperature groups when compared to NT. Conclusion: In this large, statewide study of major TBI, both ETs and LTs immediately following prehospital transport were independently associated with higher mortality and with increased TC LOS, ICU LOS, and total TC charges. Further study is needed to identify the causes of abnormal body temperature during the prehospital interval and if in-field measures to prevent temperature variations might improve outcomes.

Intramuscular administration of alfaxalone in red-eared sliders (Trachemys scripta elegans) – effects of dose and body temperature

ObjectiveTo characterise the effects of alfaxalone by intramuscular (IM) injection in red-eared slider turtles and the influence of body temperature on anaesthetic duration and depth. Study designProspective, randomised part-blinded experimental trial. AnimalsTen healthy adult female red-eared sliders. MethodsEach turtle was anaesthetized four times with 10 and 20 mg kg−1 alfaxalone at 20 and 35 °C respectively. Time to maximal effect and plateau and recovery periods were recorded. Skeletal muscle tone, presence of various reflexes, response to noxious stimuli, and heart rate were assessed. ResultsResults are given for protocols 10 mg kg−1 20 °C; 20 mg kg−1 20 °C; 10 mg kg−1 35 °C and 20 mg kg−1 35 °C, respectively: mean time (±SD) to maximal effect was 16 ± 8, 19 ± 6, 5 ± 2 and 7 ± 5 minutes; duration of the plateau phase was 13 ± 12, 28 ± 13, 8 ± 5 and 8 ± 5 minutes and recovery time was 76 ± 20, 126 ± 17, 28 ± 9 and 41 ± 20 minutes. Endotracheal intubation was successful in 80%, 100%, 0% and 30% of turtles, respectively. At 35 °C, all animals retained nociceptive sensation in the front limbs, hind limbs and vent, whereas at 20 °C a few turtles lost peripheral nociceptive sensation. Corneal and tap reflexes were retained in all trials. Mean heart rates were 30 ± 2 and 66 ± 4 beats minute−1 at 20 and 35 °C, respectively. Conclusions and clinical relevanceAlfaxalone administered IM in red-eared sliders provided smooth, rapid induction and uneventful recovery. At 35 °C either dosage provided only short (5–10 minutes) and light sedation. At 20 °C, 10 mg kg−1 provided sedation suitable for short non-invasive procedures. About 20 mg kg−1 provided anaesthesia of approximately 20 minutes duration, appropriate for induction of inhalational anaesthesia or for brief surgical procedures with supplemental analgesia.

Influence of body temperature on the evoked activity in mouse visual cortex

Optical imaging of intrinsic signals and conventional electrophysiological methods were used to investigate the correlation between the evoked activity in mouse visual cortex and core body temperature. The results show that hypothermia (25-36°C) decreases the intensity of optical imaging in the visual cortex and the imaging signal reversibly disappears at 25°C. Hyperthermia (39-41°C) increases the intensity but decreases the quality of cortical imaging when body temperature is above 40°C. The change of optical imaging was in line with that of neuronal activities and local field potentials (LFPs) directly recorded from the visual cortex at 25-39°C. Hypothermia decreases neuron firing rate and LFPs amplitude. Most of the recorded neurons ceased firing to visual stimulation at 25°C. Hyperthermia increases neuronal firing rate and LFPs amplitude. Both are reduced when body temperature is above 40 °C, though neither change was statistically significant. These results suggest: (1) Body temperature has an important impact on the visual cortical evoked activities and optical imaging generally reflects these effects when body temperature is between 25 and 39°C; (2) Optical imaging may not properly reflect the neuronal activity when body temperature is over 40°C. It is important to maintain core body temperature within 3°C of the normal body temperature to obtain verifiable results.

The influence of body temperature on image contrast in post mortem MRI

To assess the temperature dependency of tissue contrast on post mortem magnetic resonance (PMMR) images both objectively and subjectively; and to visually demonstrate the changes of image contrast at various temperatures. The study was approved by the responsible justice department and the ethics committee. The contrast of water, fat, and muscle was measured using regions of interest (ROI) in the orbit of 41 human corpses to assess how body temperature (range 2.1-39.8 °C) relates to image contrast of T1-weighted (T1W) and T2-weighted (T2W) sequences on PMMR. Regressions were calculated using the method of least squares. Three readers judged visible changes of image contrast subjectively by consensus. There was a positive relationship between temperature and contrast on T1-weighted (T1W) images and between temperature and the contrast of fat/muscle on T2-weighted (T2W) images. There was a negative relationship between temperature and the contrast of water/fat and water/muscle on T2W images. Subjectively, the influence of temperature became visible below 20 °C on T2W images, and below 10 °C on T1W images. Image contrast on PMMR depends on the temperature of a corpse. Radiologists involved in post mortem imaging must be aware of temperature-related changes in MR image contrast. To preserve technical quality, scanning corpses below 10 °C should be avoided.

Der Einsatz von Infusionswärmepumpen vermindert perioperative Hypothermie bei Katzen

Perioperative hypothermia is a common problem that must not be underestimated. There are plenty of methods to prevent or reduce heat loss during anaesthesia. The aim of this study was to evaluate the influence of warmed intravenous (IV) infusions to the perioperative decrease of body temperature of anaesthetized cats. In this randomly designed study 30 cats undergoing surgical procedures were anaesthetized with a standardized anaesthesia protocol. Fifteen cats received IV infusions with room temperature; the IV infusion of the other 15 cats was constantly warmed to 38-39°C using a fluid warming device. The development of body temperature within the first 60 minutes of anaesthesia of both groups was compared and analysed. Additionally the influence of the room temperature on the body temperature and the influence of body temperature at the end of anaesthesia on the recovery period were evaluated. After 60 minutes of anaesthesia cats receiving warmed IV infusions had a significant higher body temperature than cats receiving IV infusions with room temperature. Room temperatures lower than 26°C had a significant influence on the development of perioperative hypothermia. The evaluation of the recovery period showed a significant correlation between low body temperature at the end of anaesthesia and prolonged time until extubation on the one hand and postoperative shivering on the other hand. The present study shows that warmed IV infusions have a significant influence on the reduction of perioperative heat loss in cats. Nevertheless other additional methods to prevent heat loss are necessary to keep the patient in a normothermic range. Room temperatures play an essential role in decreasing hypothermia and should be at least 26°C. Low body temperature at the end of anaesthesia prolongs the recovery periode and enhances postoperative shivering.

Body temperature and body size affect flight performance in a damselfly

Flight performance is undoubtedly an important factor for behavioral success in flying insects. Though it is well-known that the flight performance is influenced by body temperature and body size, the relative importance of these factors is not well-understood. We performed laboratory experiments using the male-polymorphic damselfly Mnais costalis with larger territorial males and smaller non-territorial males in a population. We analyzed the effects of body temperature and body size, measured as the thoracic temperature and left hind-wing length, respectively, on two indices of flight performance: maximum lifting force and size-corrected lifting force. The latter is an index of acceleration that is related to aerial agility. The results showed that higher body temperature produced both larger maximum lifting force and larger size-corrected lifting force. In contrast, while larger size produced a larger maximum lifting force, it produced a lower size-corrected lifting force. The results of field measurements showed that territorial males had variable thoracic temperatures depending on the insolation in their territories. In contrast, non-territorial males had less variable and generally higher thoracic temperatures than territorial males as they are mostly found in sunny spots. Until now, the influence of body temperature on behavioral performance has remained unclear although considerable studies have suggested such influence. We showed, here, for the first time, combined effects of body size and body temperature on flight performance. We also showed that body temperature was influenced by the mating strategies of a damselfly. These findings provide new insights into the cost and benefits of territorial behavior in ectothermic animals.

Effects of solid body temperature on the non-Newtonian thermal elastohydrodynamic lubrication behaviour in point contacts

In order to investigate the influence of body temperature of contact solids on the lubrication performance of machine components such as gears and roll-bearings, full numerical solution for the non-Newtonian thermal elastohydrodynamic lubrication (EHL) problem in point contacts has been achieved, assuming that the body temperature is different from the temperature of the supplied lubricating oil. The Ree—Eyring rheology model has been used to describe the non-Newtonian behaviour of the lubricant. The effects of the body temperature, the slide—roll ratio, and the velocity parameter have been discussed. The results for the body temperature being higher or lower than the temperature of the supplied oil have been compared with that of the conventional thermal EHL solution, where the temperature of the contact bodies and the temperature of the supplied oil are assumed to be the same. Results show that, if the entrainment velocity is not very high, the solid body temperature plays a dominant role in the EHL behaviour; however, the influence of body temperature decreases as the entrainment velocity increases. Comparisons between the non-Newtonian and Newtonian numerical results have been made under some operating conditions. It has been shown that, compared with the Newtonian solution, the non-Newtonian property of the lubricant can always lead to lower frictional coefficient and lower temperature, but has little effect on the film thickness, no matter the temperature of the contact bodies is lower than, equal to, or higher than that of the supplied oil.

Influence of body temperature on indinavir crystallization under loop of Henle conditions

Indinavir is a protease inhibitor used in the therapy of HIV-1+ patients. It causes indinavir stone formation. It has been shown to precipitate in the loop of Henle (LH) at plasma concentrations (conc[P]) of approximately 8 mg/L. Those experiments were performed at room temperature. Given the influence of temperature on crystallization in general, and solubility of indinavir in particular, we repeated the experiments under physiological (body) temperature conditions. Test solutions contained indinavir concentrations of 100-750 mg/L at ionic strengths varying from 0 to 800 mM simulating conditions in the proximal tubule and the LH. Solutions were titrated with base (NaOH) to find the pH value where nucleation is initiated. Experiments were conducted at room temperature (20 degrees C) and repeated under constantly monitored (body) temperature (37 degrees C). Experiments at 20 degrees C confirmed our previous results. At 37 degrees C, the relationship between pH and indinavir concentration remained inversely proportional. Again, the LH was confirmed as the most likely localization of crystallization. However, at 37 degrees C precipitation occurred at a lower urinary concentration (100 versus 125 mg/L) and within a lower pH range (6.67-7.26 versus 7.23-7.44). This lower urinary concentration corresponds to a lower conc[P] [critical value (CV)] of 6.41 mg/L, as compared with 8.01 mg/L at 20 degrees C. The CV is even lower at 37 degrees C than previously assumed. Plasma peak concentration above the CV of 6.4 mg/L will induce crystallization in the LH and should be avoided.

Influence of body temperature on the BOLD effect in murine SCC tumors.

Changes in the blood oxygen level dependent (BOLD) enhancements in tumors (squamous cell carcinoma, (SCCVII)) implanted in mice maintained at core temperatures of 30 degrees C or 37 degrees C were measured using MRI and compared to tumor oxygen levels obtained using an oxygen-sensitive Eppendorf electrode. Tumors were implanted in a hindleg of the mice intramuscularly. Tumor-bearing mice were imaged by BOLD MRI, while first breathing air and then carbogen (95% O2, 5% CO2) for 15-min intervals at a core temperature of 30 degrees C. After an equilibration period, the identical regimen was conducted with the same animal maintained at 37 degrees C. This procedure was repeated with additional mice starting at 37 degrees C followed by imaging at 30 degrees C. Likewise, oxygen electrode measurements of the tumor were determined at core temperatures of 30 degrees C and 37 degrees C. The Eppendorf measurements showed that tumors in animals maintained at 30 degrees C were significantly more hypoxic than at 37 degrees C. MRI studies demonstrated stronger BOLD enhancement at 30 degrees C than at 37 degrees C, suggesting significant changes in hypoxia and/or blood flow in tumors at these temperatures. The findings of the study stress the importance of maintaining normal core temperature when assessing tumor oxygen status using functional imaging modalities or oxygen-sensitive electrodes.

Assessment of body composition by air-displacement plethysmography: influence of body temperature and moisture

BackgroundTo investigate the effect of body temperature and moisture on body fat (%fat), volume and density by air-displacement plethysmography (BOD POD).Methods%fat, body volume and density by the BOD POD before (BOD PODBH) and immediately following hydrostatic weighing (BOD PODFH) were performed in 32 healthy females (age (yr) 33 ± 11, weight (kg) 64 ± 14, height (cm) 167 ± 7). Body temperature and moisture were measured prior to BOD PODBH and prior to BOD PODFH with body moisture defined as the difference in body weight (kg) between the BOD PODBH and BOD PODFH measurements.ResultsBOD PODFH %fat (27.1%) and body volume (61.5 L) were significantly lower (P ≤ 0.001) and body density (1.0379 g/cm3) significantly higher (P ≤ 0.001) than BOD PODBH %fat (28.9%), body volume (61.7 L), and body density (1.0341 g/cm3). A significant increase in body temperature (~0.6°C; P ≤ 0.001) and body moisture (0.08 kg; P ≤ 0.01) were observed between BOD PODBH and BOD PODFH. Body surface area was positively associated with the difference in %fat independent of changes in body temperature and moisture, r = 0.30, P < 0.05.ConclusionThese data demonstrate for the first time that increases in body heat and moisture result in an underestimation of body fat when using the BOD POD, however, the precise mechanism remains unidentified.

Influence of body temperature on food assimilation and locomotor performance in white-striped grass lizards, Takydromus wolteri (Lacertidae)

Influence of body temperature on food assimilation and locomotor performance was studied in adult white-striped grass lizards ( Takydromus wolteri) from a population in Chuzhou (Anhui, Eastern China). Food passage time dramatically decreased with increase in body temperature within the range from 26°C to 34°C, and then nearly levelled at higher body temperatures. Lizards overall gained net mass at 26°C, 28°C and 30°C and lost mass at 32°C and 34°C. Daily production of faeces (mass-specific) was affected by body temperature and, when influence of variation in the total food energy intake was removed by an ANCOVA, lizards at 26°C were found to produce faeces that contained significantly lower energy as compared with those at higher body temperatures. The total energy of urates was affected by the total food energy intake, but an ANCOVA with the total food energy intake as the covariate showed that lizards at different body temperatures did not produce urates that differed in energy. Within the temperature range considered, daily production of urates (mass-specific), apparent digestive coefficient (ADC) and assimilation efficiency (AE) were not affected by body temperature, although both ADC and AE were apparently greater in lizards at 26°C. Both locomotor stamina and sprint speed increased with increase in body temperature within the range from 18°C to 30°C, and then decreased at higher temperatures. Inter-individual differences were a significant source of variation in locomotor performance. Except for ADC and AE, all traits examined were significantly affected by body temperature, although thermal sensitivities differed considerably among traits. Within the body temperature range considered, 26°C was the most suitable body temperature for somatic tissue growth, and 30°C was an optimal body temperature for locomotor performance.