Body Temperature In Cold Research Articles

Depressing Ubiquitin-Dependent Proteolysis in a Hibernator Whose Body Temperature Is Normally Variable: The Common Tenrec

In a canonical mammalian hibernator like a ground squirrel, the cold body temperatures (Tb) of the torpid squirrel depresses protein degradation at the level of the 26S proteasome. Ubiquitylation per se is less temperature sensitive as ubiquitylation rates of colder temperatures continue at 30% to 60% of the maximal rates of warmer temperatures. This leads to an accumulation of ubiquitin-conjugated proteins of 2-3 fold in torpid squirrels as compared to active squirrels. The common tenrec is a bizarre Afrotherian placental mammal with many plesiomorphic traits such as a cloaca, internal testes, indeterminate growth, and the smallest brain of all extant mammals with very little neocortex. Interestingly, these tenrecs may be fully active with a Tb of 12°C or hibernating at a Tb of 28°C. Moreover, oxygen consumption rates may vary 25 fold in active tenrecs. We found expected decreases of 26S proteolytic activity at low temperatures. Capacitance for proteolysis varied by state and there was no evidence that torpor per se would arrest protein degradation. Indeed, in sharp contrast to the squirrel, ubiquitylation rates were essentially unaffected by temperature and ranged at colder temperatures from 80% to 90% of the maximal ubiquitylation rates. In other words, the only in vitro evidence for the control of ubiquitin-dependent proteolysis that we found would only be available to very cold tenrecs independent of if they were active or torpid. However, ubiquitin-conjugate concentrations appear low but unaffected by state. All in all, we hypothesize a ‘Life in the Slow Lane’ model for tenrecs wherein an inability to effectively regulate proteolysis led to a modest rate of degradation that is not as affected by changes incurred by torpor state or changes in Tb. NSF and Department of Education (GAANN). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Moral and Cultural Values in the Story of Putri Pukes from Central Aceh

Princess Pukes is the small kingdom's beloved girl and the only child. Because she denied his mother, who said she should not look back when escorted to the groom's house before passing through the Pukes area. But because she couldn't stand her parents' choice, the princess accidentally looked back, suddenly lightning struck, and the rain was weighty. So Putri Pukes took shelter in the cave. Inside the cave, Putri Pukes stood in a corner because of her cold body temperature. Slowly the princess's body hardened and turned into stone. The prince who entered first heard the news that the princess had turned to stone. Enthusiastically, he prayed to be turned into stone. Ultimately, the love story between Princess Pukes and the prince ends tragically. This study aims to (1) describe the moral values ??in the Putri Pukes folklore, (2) describe the cultural values ??in the Putri Pukes folklore, and the source of the data taken is the Putri Pukes folklore. The results of this study aim to be an example for the younger generation and to have an extensive and positive influence, especially on those who have read this story, so as not to imitate the wrong attitude of the Pukes daughter, who violates the message of her parents. However, to reduce incidents like this, always teach other younger generations to obey and listen to their parents' messages to get good right from Allah SWT.

CREG1 promotes uncoupling protein 1 expression and brown adipogenesis in vitro.

Brown adipocytes play a critical role for adaptive thermogenesis to regulate body temperature in cold or to circumvent diet-induced obesity. In this study, we investigated the role of cellular repressor of E1A-stimulated genes 1 (CREG1) on brown adipogenesis and uncoupling protein 1 (UCP1) expression by using in vitro culture models. In murine mesenchymal stem cell line C3H10T1/2, Creg1 mRNA expression significantly increased in a time-dependent manner along with Ucp1 mRNA induction in brown adipogenesis. Creg1 gene overexpression upregulated the expression of brown fat-related genes including Ucp1 but its suppression downregulated these gene expression in C3H10T1/2 cells. Unlike the brown adipogenesis, Creg1 mRNA expression decreased significantly after differentiation stimulation in white adipogenesis of 3T3-L1 cells. Either Creg1 gene overexpression or suppression hardly affected white adipogenesis. In addition, CREG1 protein stimulated brown adipogenesis and rescued the adipogenesis in the absence of thyroid hormone in C3H10T1/2 cells. In reporter assay, CREG1 induction stimulated Ucp1 promoter activity, which was enhanced by co-expression with thyroid hormone receptors. The effect of CREG1 on Ucp1 promoter activity was also stimulated by retinoic acid. These results strongly suggest that CREG1 plays an important role on the regulation of UCP1 expression and brown adipogenesis.

Ablation of PM20D1 reveals N-acyl amino acid control of metabolism and nociception

N-acyl amino acids (NAAs) are a structurally diverse class of bioactive signaling lipids whose endogenous functions have largely remained uncharacterized. To clarify the physiologic roles of NAAs, we generated mice deficient in the circulating enzyme peptidase M20 domain-containing 1 (PM20D1). Global PM20D1-KO mice have dramatically reduced NAA hydrolase/synthase activities in tissues and blood with concomitant bidirectional dysregulation of endogenous NAAs. Compared with control animals, PM20D1-KO mice exhibit a variety of metabolic and pain phenotypes, including insulin resistance, altered body temperature in cold, and antinociceptive behaviors. Guided by these phenotypes, we identify N-oleoyl-glutamine (C18:1-Gln) as a key PM20D1-regulated NAA. In addition to its mitochondrial uncoupling bioactivity, C18:1-Gln also antagonizes certain members of the transient receptor potential (TRP) calcium channels including TRPV1. Direct administration of C18:1-Gln to mice is sufficient to recapitulate a subset of phenotypes observed in PM20D1-KO animals. These data demonstrate that PM20D1 is a dominant enzymatic regulator of NAA levels in vivo and elucidate physiologic functions for NAA signaling in metabolism and nociception.

P04 : Role of antiapoptotic signaling in mammalian hibernation

In the context of normal cell turnover, apoptosis is an essential natural phenomenon. Apoptosis depends on signals that promote cell death – proapoptotic pathways “and those that neutralize these signals” anti-apoptotic pathways. We proposed that changes in anti-apoptotic proteins would counteract stresses associated with hibernation (e.g. cold body temperatures, changes in metabolic requirements, ischemia–reperfusion) in thirteen-lined ground squirrels ( Spermophilus tridecemlineatus ). Immunoblotting was used to analyze expression of proteins in three tissues. In brain, phospho-Bcl-2 (T56), phospho-Bcl-2(S70), Bcl-3, xIAP, Mcl-1, and BI-1 increased significantly during torpor (compared with euthermia) whereas cIAP was unaltered. In liver, all proteins were unchanged except for cIAP and Bcl-3 that decreased and BI-1 which increased during torpor. In kidney, the majority of proteins did not change except for a decrease in phospho-Bcl-2(T56) and an increase in BI-1 during torpor. The data show that anti-apoptotic pathways have organ-specific responses in hibernators with a prominent potential role in brain.

Peculiarities of the Leidenfrost effect application for drag force reduction

An article presents the comparison of the energy consumption of the cold (at an ambient temperature) and hot (wrapped by the vapor film) spherical body, moving in the liquid (water and electrolyte FC-72). Taken in consid-eration that spherical body is from stainless steel with di-ameter 0.02 m. Body’s velocity was changed from 0.03 to 32.5 m/s; liquid and cold body temperature was kept at 20°C; hot body temperature was equal to 500°C. During the analysis was stated that the hot body, surrounded by the vapor film, moves faster, but from the energy economy view, boiling crisis (Leidenfrost effect) application in order to reduce drag force of the moving body, is reasonable in the case of electrolyte, but is doubtful for the water case. DOI: http://dx.doi.org/10.5755/j01.mech.20.3.6775

154 Adaptations of cardiac muscle function during mammalian hibernation

Entry into torpor during hibernation has major consequences for mammalian heart. Heart must continue to beat at cold body temperatures and although heart rate is much slower, contractile force must increase to deal with the higher viscosity of blood. Muscle remodelling is needed. We examined responses of the GATA-4 and Nkx2–5 transcription factors that are essential regulators of cardiac hypertrophic growth in thirteen-lined ground squirrels (Spermophilus tridecemlineatus) over a time course of torpor-arousal. Immunoblot analysis showed that both GATA4 and phosphorylated-GATA4(S262) increased significantly during entrance into torpor and GATA4 also showed enhanced binding to DNA. However, Nkx2–5 did not change. Two downstream targets of GATA-4, Troponin C and Troponin I, also showed increased protein levels during entrance into torpor. The data indicate that GATA-4 regulates expression of downstream genes that are important to heart function during transition periods. However, unlike other situations, GATA-4 and Nkx2–5 do not cooperate during torpor.

Neuroprotection: Lessons from hibernators

Mammals that hibernate experience extreme metabolic states and body temperatures as they transition between euthermia, a state resembling typical warm blooded mammals, and prolonged torpor, a state of suspended animation where the brain receives as low as 10% of normal cerebral blood flow. Transitions into and out of torpor are more physiologically challenging than the extreme metabolic suppression and cold body temperatures of torpor per se. Mammals that hibernate show unprecedented capacities to tolerate cerebral ischemia, a decrease in blood flow to the brain caused by stroke, cardiac arrest or brain trauma. While cerebral ischemia often leads to death or disability in humans and most other mammals, hibernating mammals suffer no ill effects when blood flow to the brain is dramatically decreased during torpor or experimentally induced during euthermia. These animals, as adults, also display rapid and pronounced synaptic flexibility where synapses retract during torpor and rapidly re-emerge upon arousal. A variety of coordinated adaptations contribute to tolerance of cerebral ischemia in these animals. In this review we discuss adaptations in heterothermic mammals that may suggest novel therapeutic targets and strategies to protect the human brain against cerebral ischemic damage and neurodegenerative disease.

Thermoregulation and Heat Loss Prevention After Birth and During Neonatal Intensive-Care Unit Stabilization of Extremely Low-Birthweight Infants

Extremely low-birthweight infants have inefficient thermoregulation due to immaturity and may exhibit cold body temperatures after birth and during their first 12 hours of life. Hypothermia in these infants can lead to increased morbidity and mortality. Anecdotal notes made during our recent study revealed extremely low-birthweight infants' temperatures decreased with caregiver procedures such as umbilical line insertion, intubations, obtaining chest x-rays, manipulating intravenous lines, repositioning, suctioning, and taking vital signs during the first 12 hours of life. Therefore, nursing interventions should be undertaken to prevent heat loss during these caregiver procedures. Nurses can improve the thermal environment for extremely low-birthweight infants by prewarming the delivery room and placing the infant in a plastic bag up to the neck during delivery room stabilization to prevent heat loss. JOGNN, 36, 280-287; 2007. DOI: 10.1111/J.1552-6909.2007.00149.x.

The Validity of Mass Body Temperature Screening with Ear Thermometers in a Warm Thermal Environment

Identification of people who have a fever in public places during the occurrence of emerging infectious diseases is essential for controlling disease spread. The measurement of body temperature could identify infected persons. The environment affects body temperature, but little is known about the validity of measurements under different thermal environments. Therefore, the aim of this study was to determine the validity of measuring body temperature in cold and warm environments. We recruited 50 participants aged 18-69 years (26 males, 24 females) to measure body temperature using an axillary thermometer and an ear thermometer and by infrared thermal imaging (thermography). The body temperature obtained with an axillary thermometer was used as a reference; receiver operating characteristic (ROC) analysis was conducted to determine the validity of temperatures obtained by measurement with an ear thermometer and thermography at 36.7°C (median of the axillary body temperature). The area under the ROC curve (AUC) indicates the validity of measurements. The AUC for ear thermometers in a warm environment (mean temperature: 20.0°C) showed a fair accuracy (AUC: 0.74 [95% CI: 0.64-0.83]), while that (AUC: 0.62 [95% CI: 0.51-0.72]) in a cold environment (mean temperature: 12.6°C) and measurements with thermography used in both environments (AUC: 0.57 [95% CI: 0.45-0.68] in a warm environment and AUC: 0.65 [95% CI: 0.54-0.76] in a cold environment) showed a low accuracy. In conclusion, in a warm environment, measurement of body temperature with an ear thermometer is a valid procedure and effective for mass body temperature screening.

Extremely low birth weight preterm infants lack vasomotor response in relationship to cold body temperatures at birth

ObjectiveThis study evaluated peripheral vasoconstriction in ELBW infants when body temperature decreased during the first 12-hours of life.DesignAn exploratory, within-subjects design with 10 ELBW infants. Abdominal and foot temperatures were measured every minute. Peripheral vasoconstriction (abdominal > peripheral temperature by 2° C) and abdominal-peripheral temperature difference were also evaluated.ResultsAbdominal and peripheral temperatures were significantly correlated within each infant. One 880 g infant exhibited isolated peripheral vasoconstriction; a 960 g infant had abdominal temperatures more than 1° C higher than peripheral temperatures. Eight smaller infants exhibited no peripheral vasoconstriction and spent most of their observations with peripheral greater than abdominal temperatures. In 8 infants, mean temperature difference was significantly higher when abdominal temperature was less than 36.5° C.ConclusionMost ELBW infants did not exhibit peripheral vasoconstriction during their first 12-hours of life, despite low temperatures. ELBW infants’ vasomotor control may be immature during this period.

Extremely low birth weight preterm infants lack vasomotor response in relationship to cold body temperatures at birth

Extremely low birth weight preterm infants lack vasomotor response in relationship to cold body temperatures at birth

Function of muscle-type lactate dehydrogenase and citrate synthase of the Galápagos marine iguana, Amblyrhynchus cristatus, in relation to temperature

The Galápagos marine iguana, Amblyrhynchus cristatus, is unique among lizards in foraging subtidally, leading to activity across a broad range of ambient temperatures (∼ 14–40 °C). To determine whether the marine iguana shows any biochemical changes consistent with maintaining enzyme function at both warm and cold body temperatures, we examined the function of the aerobic enzyme citrate synthase (CS) and the muscle isoform of the anaerobic enzyme lactate dehydrogenase (A 4-LDH) in A. cristatus and a confamilial species, Iguana iguana, from 14 to 46 °C. We also deduced amino acid sequences from cDNA of each enzyme. In CS, despite two amino acid substitutions, we found no difference in the apparent Michaelis–Menten constant K m of oxaloacetate at any temperature, indicating that the substrate affinity of CS in A. cristatus has not adapted to changes in thermal environment. In A 4-LDH, we used site-directed mutagenesis to show that the substitutions T9A and I283V ( A. cristatus → I. iguana) individually have no effect on kinetics, but together significantly decrease the K m of pyruvate and catalytic rate constant ( k cat) of the A. cristatus ortholog. Thus, our data show that A. cristatus A 4-LDH has not become cold adapted in response to this species' aquatic foraging behavior, and instead may be consistent with moderate warm adaptation with respect to the I. iguana ortholog.

Thermoregulation and Heat Loss Prevention After Birth and During Neonatal Intensive‐Care Unit Stabilization of Extremely Low‐Birthweight Infants

Extremely low-birthweight infants have inefficient thermoregulation due to immaturity and may exhibit cold body temperatures after birth and during their first 12 hours of life. Hypothermia in these infants can lead to increased morbidity and mortality. Anecdotal notes made during our recent study revealed extremely low-birthweight infants' temperatures decreased with caregiver procedures such as umbilical line insertion, intubations, obtaining chest x-rays, manipulating intravenous lines, repositioning, suctioning, and taking vital signs during the first 12 hours of life. Therefore, nursing interventions should be undertaken to prevent heat loss during these caregiver procedures. Nurses can improve the thermal environment for extremely low-birthweight infants by prewarming the delivery room and placing the infant in a plastic bag up to the neck during delivery room stabilization to prevent heat loss.

Susceptibility of biological membranes to lipid peroxidation and enzymatic antioxidant defense in a temperature‐acclimated teleost fish

As temperature changes, many poikilotherms defend membrane fluidity by altering the phospholipid composition of their membranes. This membrane remodeling, coupled with increased oxidative capacity at cold body temperatures, may affect susceptibility to lipid peroxidation (LPO) and necessitate more robust antioxidant defenses. Our study quantifies LPO susceptibility, oxidative capacity, and antioxidant enzyme activity in glycolytic muscle of bluegill, Lepomis macrochirus, acclimated to 5°C or 25°C for 8 weeks. Rates of LPO were quantified in microsomal membranes using thiobarbituric acid reactive substances (TBARS) and C11-BODIPY, a fluorescent lipophilic reporter. Oxidative capacity was determined by the activity of cytochrome c oxidase (CCO), and activities of superoxide dismutase (SOD) and catalase (CAT) represented the antioxidant response. Activity of CCO increases by 1.7-fold in cold-acclimated fish indicating enhanced oxidative capacities. Yet, neither LPO susceptibility, nor antioxidant responses differ significantly between treatments. Support from Ohio University Provost’s Undergraduate Research Fund to DRBM, Peter K. Lauf Travel Award (Ohio Physiological Society) to JMG, and Ohio University Research Committee to ELC.

Physiological mismatches in protein degradation and their implications for coordinated metabolic suppression during mammalian hibernation

It is widely held that processes of both anabolism and catabolism must be equally suppressed in order to survive an extended period of metabolic depression. Mammalian hibernation is marked by sojourns to very cold body temperatures (as low as −2° C) followed by rapid returns to euthermy (36–37° C). Protein synthesis during torpor is markedly depressed in concordance with metabolic demands. Continued degradation of proteins would rapidly deplete cellular pools of key regulatory proteins and could jeapordize the animal's return to euthermy. We examined ubiquitin-mediated proteolysis which consists of two major steps: the tagging of a protein substrate by ubiquitin and the protein substrate's subsequent degradation by the 26S proteasome. There is a 2–3 fold elevation of ubiquitin conjugate concentrations during torpor: an unexpected result that seemingly would suggest increased proteolytic activity. However, the cold temperatures typical of torpor markedly reduce the degradation process. Here, we show that ubiquitylation per se continues at a moderate rate (>30% of maximal activity) at 0° C. Thus, while proteolysis is depressed during torpor as would be expected, the mechanism results in a physiological mismatch that must be resolved upon arousal. We discuss the implications of this lack of coordinated metabolic depression.

Intracellular oxygen diffusion: the roles of myoglobin and lipid at cold body temperature.

Cold temperature can constrain the rate of oxygen movement through muscle cells of ectothermic animals because the kinetic energy of the solvent-solute system decreases and the viscosity of the aqueous cytoplasm increases during cooling within the physiological range of body temperatures. These factors affect the movement of both dissolved oxygen and oxymyoglobin, the two predominant routes of intracellular oxygen diffusion in vertebrate oxidative muscles. In addition, reductions in temperature have been shown to increase the affinity of myoglobin for oxygen and to slow the rate of Mb O2-dissociation, compromising the ability of this oxygen-binding protein to facilitate intracellular oxygen diffusion. Experiments with both seasonally cold-bodied fishes and polar fish species suggest that several factors combine to overcome these limitations in delivery of oxygen from the blood to the mitochondria. First, reductions in body temperature induce increases in mitochondrial density of oxidative muscle cells, reducing the mean diffusional pathlength for oxygen between capillaries and mitochondria. Second, cold body temperature in both temperate-zone and polar fishes is frequently correlated with a high content of neutral lipid in oxidative muscles, providing an enhanced diffusional pathway for oxygen through the tissue. Third, recent data indicate that myoglobins from fish species bind and release oxygen more rapidly at cold temperature than do those from mammals. Data from both oxidative skeletal muscle and cardiac muscle of fishes suggest that these factors in various combinations contribute to enhance the aerobically supported mechanical performance of the tissues at cold cellular temperatures.

Amphibian Declines in the Greater Yellowstone Ecosystem: Toads with Protection from Bacterial Disease

During the past forty years, biologists have become increasingly concerned about the decline and disappearance of various amphibian species throughout the world (Wyman 1990, Wake 1991). An example of an amphibian decline in western North America is that of the Boreal Toad (Bufo boreas). A previously widespread and abundant species, the Boreal Toad has undergone large population declines and is now a candidate for threatened and endangered status in the eastern half of its range (Stebbins and Cohen 1995, Federal Register 1995). Decreases in Boreal Toad abundance and distribution have been observed in Colorado, eastern Wyoming, and eastern Utah (Com et al. 1989). From 1971-82, eleven Boreal Toad populations disappeared from the West Elk Mountains of Colorado (Carey 1993). During this eleven-year period, numerous individuals were observed exhibiting symptoms of redleg, a well­documented disease in amphibians caused by the bacterium Aeromonas hydrophila (Russel 1898, Emerson and Norris 1905, Kulp and Borden 1942, Reed and Toner 1942, Dusi 1949, Hunsaker and Potter 1960, Hird et. al. 1981, Nyman 1986, Carey 1993). This disease was considered responsible for the decline and ultimate extinction of these eleven toad populations. These extinctions led Carey to propose a hypothesis regarding the disease process which is stated as follows: (1) Some environmental factor or synergistic effects of more than one factor changes sufficiently to cause sublethal "stress;" (2) This stress directly causes suppression of the immune system, or indirectly causes immunosuppression by effecting elevated secretion of adrenal cortical hormones; (3) Immunosuppression, coupled with the apparent effect of cold body temperatures on the ability of immune systems of ectothermic animals to fight disease, leads to infection by Aeromonas or other infectious agents, and to subsequent death of individuals and extinction of populations.

Ultrastructure of Aerobic Muscle in Antarctic Fishes may Contribute to Maintenance Of Diffusive Fluxes

ABSTRACT Quantitative ultrastructural analyses were performed on red (oxidative) and white (glycolytic) skeletal muscles from two species of antarctic fish to identify features of subcellular structure that may be related to muscle metabolism at cold body temperature. Trematomus newnesi (Boulenger) is an active pelagic species and Notothenia gibberifrons (Lönnberg) is a sluggish bottom-dweller. White fibres of both species are poorly vascularized [capillary density, NA(c,f), for T. newnesi is 73.9±11.3 mm−2; for N. gibberifrons is 76.0±14.1 −2], and have low percentages of cell volume occupied by mitochondria [volume density, Vv(mit,f), for T. newnesi is 0.014±0.005; for N. gibberifrons is 0.006±0.003]. Ultrastructure of oxidative fibres in both species resembles that of cold-acclimated temperate-zone fishes. Mitochondrial volume densities of red fibres reflect differences in ecotype between species [Vv(mit,f) for T. newnesi is 0.348±0.012; for N. gibberifrons is 0.249± 0.007], The less clustered array of mitochondria in oxidative fibres of T. newnesi compared with N. gibberifrons may support an equivalent flux of aqueous metabolites between mitochondrial and cytoplasmic compartments, despite a greater mean intracellular diffusion distance (τh) between these compartments in T. newnesi than in N. gibberifrons (τh=1.05±0.07μm and 0.77±0.06μm, respectively). Although Vv(mit,f) is higher in red fibres of the active species, capillary supply is less extensive [capillary length density, Jv(c,f), for T. newnesi is 481.3±49.0mmmm−3; N. gibberifrons is 696.3±33.7 mm mm’− 3] and the maximal diffusion-distance for oxygen is greater in T. newnesi than in N. gibberifrons (Krogh’s radius, N=26.3±1.64μm and 21.5±0.51 μm, respectively). A mismatch appears to exist between oxygen supply [Jv(c,f)] and oxygen demand [Vv(mit,f)] in T. newnesi red fibres in view of published data for other fishes. The twofold higher volume density of lipid [Vv(lip,f)] in T. newnesi compared with N. gibberifrons may resolve this paradox [Vv(lip,f) is 0.026±0.002 and 0.012±0.004, respectively]. Because oxygen is at least four times more soluble in lipid than in aqueous cytoplasm, lipid may enhance oxygen flux through oxidative muscle and play a role similar to myoglobin in these myoglobin-poor fishes.

Body temperature cues as contextual stimuli: Modulation of hypothermia-induced retrograde amnesia

Three experiments investigated whether the retention of passive avoidance training after the induction of amnesia by hypothermia could be modulated by the presence or absence of cold body temperature cues. In Experiment 1A, the cues for recovery from amnesia produced by a recooling treatment were erased by a 5, 10, or 15 min, but not by a 1 min, immersion in normothermic water. Similarly, Experiment 1B noted the erasure of the recooling reactivation effect by a 10 or 20 min immersion in normothermic water immediately after the recooling episode. In neither of these experiments did the rewarming treatment artifactually increase the activity of control animals. That the presentation of cold body temperature cues after an erasure treatment would again provide access to the target memory was also suggested in Experiment 1B. Experiment 2 confirmed this effect; over multiple test sessions animals displayed recovery from amnesia, erasure of the recovery effect, and recovery from erasure, in accordance with the availability of cold state cues. Multiple test sessions produced no memory recovery in control animals. Reactivation was not based upon stress per se as exposure to temperature extremes in recooling/rewarming failed to alleviate amnesia. In the present paradigm memory retrieval appears importantly linked to temperature-related contextual cues.