PCL reconstruction. In vitro biomechanical comparison of ''isometric'' versus single and double-bundled ''anatomic'' grafts

The analgesic tramadol inhibits the neuronal reuptake of norepinephrine and 5-hydroxytryptamine, facilitates 5-hydroxytryptamine release, and activates mu-opioid receptors. Each of these actions is likely to influence thermoregulatory control. We therefore tested the hypothesis that tramadol inhibits thermoregulatory control. Eight volunteers were evaluated on four study days, on which they received no drugs, tramadol 125 mg, tramadol 250 mg, and tramadol 250 mg with naloxone, respectively. Skin and core temperatures were gradually increased until sweating was observed and then decreased until vasoconstriction and shivering were detected. The core temperature triggering each response defined its threshold. Tramadol decreased the sweating threshold by -1.03 +/- 0.67 degrees C microgram-1.mL (r2 = 0.90 +/- 0.12). Tramadol also decreased the vasoconstriction threshold by -3.0 +/- 4.0 degrees C microgram-1.mL (r2 = 0.94 +/- 0.98) and the shivering threshold by -4.2 +/- 4.0 degrees C microgram-1.mL(r2 = 0.98 +/- 0.98). The sweating to vasoconstriction interthreshold range nearly doubled from 0.3 +/- 0.4 degree C to 0.7 +/- 0.6 degree C during the administration of large-dose tramadol (P = 0.04). The addition of naloxone only partially reversed the thermoregulatory effects of tramadol. The thermoregulatory effects of tramadol thus most resemble those of midazolam, another drug that slightly decreases the thresholds triggering all three major autonomic thermoregulatory defenses. In this respect, both drugs reduce the "setpoint" rather than produce a generalized impairment of thermoregulatory control. Nonetheless, tramadol nearly doubled the interthreshold range at a concentration near 200 ng/mL. This indicates that tramadol slightly decreases the precision of thermoregulatory control in addition to reducing the setpoint. IMPLICATIONS: The authors evaluated the effects of the analgesic tramadol on the three major thermoregulatory responses: sweating, vasoconstriction, and shivering. Tramadol had only slight thermoregulatory effects. Its use is thus unlikely to provoke hypothermia or to facilitate fever.     

Insiders, outsiders, and efficiency in a National Science Foundation panel.

Assessed the efficiency of the peer review system during 3 National Science Foundation panel meetings held in 1982 and 1983. During these meetings, nearly 200 proposals received almost 1,400 reviews from "insiders" (panel members) and "outsiders" (ad hoc reviewers). Although the ratio of ad hoc time to panelist time was about 2:1, ad hoc reviewers' quantitative ratings had scant independent influence on final proposal ratings. Nevertheless, it may be that ad hoc reviewers provided crucial qualitative information, acting more as expert witnesses than as judges. The outcome of about a third of the proposals (the very good and the very poor) could be reliably predicted by independent panelist assessments that occurred before the panel meetings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selected temperature correlates with intensity of fever in rats

Fever is considered due to an elevation of the setpoint of body temperature. The temperature is regulated at a higher level and the higher temperature is established by activation of the heat-seeking thermoeffectors. However, it is surprising that, for this widely accepted hypothesis, there is little experimental evidence of the setpoint shifting to a higher level. The present study shows, for the first time, a significant correlation between the magnitude of the temperature rise in fever and the ambient temperature selected by rats in a thermal gradient.     

Leg heat content continues to decrease during the core temperature plateau in humans anesthetized with isoflurane

BACKGROUND: Sufficient hypothermia during anesthesia provokes thermoregulatory responses, but the clinical significance of these responses remains unknown. Nonshivering thermogenesis does not increase metabolic heat production in anesthetized adults. Vasoconstriction reduces cutaneous heat loss, but the initial decrease appears insufficient to cause a thermal steady state (heat production equaling heat loss). Accordingly, the authors tested the hypotheses that: 1) thermoregulatory vasoconstriction prevents further core hypothermia; and 2) the resulting stable core temperature is not a thermal steady state, but, instead, is accompanied for several hours by a continued reduction in body heat content. METHODS: Six healthy volunteers were anesthetized with isoflurane (0.8%) and paralyzed with vecuronium. Core hypothermia was induced by fan cooling, and continued for 3 h after vasoconstriction in the legs was detected. Leg heat content was calculated from six needle thermocouples and skin temperature, by integrating the resulting parabolic regression over volume. RESULTS: Core temperature decreased 1.0 +/- 0.2 degrees C in the 1 h before vasoconstriction, but only 0.4 +/- 0.3 degrees C in the subsequent 3 h. This temperature decrease, evenly distributed throughout the body, would reduce leg heat content 10 kcal. However, measured leg heat content decreased 49 +/- 18 kcal in the 3 h after vasoconstriction. CONCLUSIONS: These data thus indicate that thermoregulatory vasoconstriction produces a clinically important reduction in the rate of core cooling. This core temperature plateau resulted, at least in part, from sequestration of metabolic heat to the core which allowed core temperature to remain nearly constant, despite a continually decreasing body heat content.     

Eucapnic hypoxia lowers human cold thermoregulatory response thresholds and accelerates core cooling

Hypoxia lowers the basic thermoregulatory responses of animals and humans. In cold-exposed animals, hypoxia increases core temperature (Tco) cooling rate and suppresses shivering thermogenesis. In humans, the experimental effects of hypoxia on thermoregulation are equivocal. Also, the effect of hypoxia has not been separated from that of hypocapnia consequent to hypoxic hyperventilation. To determine the isolated effects of hypoxia on warm and cold thermoregulatory responses and core cooling during mild cold stress, we examined the Tco thresholds for sweating, vasoconstriction, and shivering as well as the core cooling rates of eight subjects immersed in 28 degrees C water under eucapnic conditions. On 2 separate days, subjects exercised on an underwater cycle ergometer to elevate Tco above the sweating threshold. They then rested and cooled until they shivered vigorously. Subjects inspired humidified room air during the control trial. For the eucapnic hypoxia trial, they inspired 12% O2-balance N2 with CO2 added to maintain eucapnia. Eucapnic hypoxia lowered the Tco thresholds for vasoconstriction and shivering by 0.14 and 0.19 degrees C, respectively, and increased core cooling rate by 33% (1.83 vs. 1.38 degrees C/h). These results demonstrate that eucapnic hypoxia enhances the core cooling rate in humans during mild cold stress. This may be attributed in part to a delay in the onset of vasoconstriction and shivering as well as increased respiratory heat loss during hypoxic hyperventilation.     

Thermoregulatory responses of circum-pubertal children

Passive temperature lability of nine circum-pubertal children [11.4 (1.2) years] was compared to that of nine young adult males [26.6 (5.2) years]. Each subject completed a 20-min period of exercise, followed immediately by post-exercise immersion in water at 28 degrees C. The aim of the exercise protocol was to induce a steady rate of sweating (Esw) while the postexercise immersion period induced cooling of the core region (tympanic temperature: Tty). The Tty values (relative to rest, delta Tty) at which sweating abated and at which shivering commenced were defined as the thresholds for the cessation of sweating and onset of shivering, respectively. While there was no significant difference between the delta Tty sweating thresholds, the onset of shivering, as reflected in the oxygen uptake (VO2) response, occurred at significantly higher (P < 0.05) delta Tty values in the children [mean (SD): - 0.07 (0.07) degrees C] than in the adults [ -0.22 (0.10) degrees C]. The slope of the Esw/delta Tty relationship was found to be significantly lower in the children (z = -5.64; P < 0.05), while the slopes of the VO2/delta Tty relationship were not significantly different (z = -0.84; P > 0.05). Skin blood perfusion was measured at the forehead (SkBP), and the slope of the SkBP/delta Tty relationship across the null-zone was significantly less in the children than in the adults (z = -2.13; P < 0.05) with the greatest reduction in perfusion occurring prior to the offset of sweating in the children. The subjective ratings of thermal comfort indicated that the children were more sensitive to changes in core temperature than the adults. It is concluded that maturation plays an important role in modifying thermoregulatory responses to deviations in core temperature. These results suggest that there may be differences in thermoregulatory "strategies" which are maturationally related.     

Fluorescein angiography in syphilitic retinal vasculitis

Bilateral injections of norepinephrine bitartrate (5.0-20.0 microng) into the preoptic region and anterior hypothalamus were always followed by a reduction in core temperature and rate of behaviorally obtaining radiant heat in cold-exposed (5 degrees C) squirrel monkeys regardless of whether the temperature of this region was experimentally raised (40-42 degrees C) or lowered (32-34 degrees C). Decreases in tail temperature following injections of norepinephrine indicated that vasoconstriction was also associated with the reduction in body temperature and behavioral responses. Since conflicting behavioral and autonomic responses are observed following injections of norepinephrine, it is suggested that norepinephrine may be affecting thermoregulatory effector pathways nonspecifically rather than altering the set point about which body temperature is regulated.     

When pleasure begets pleasure: Recipient responsiveness as a determinant of physical pleasuring between heterosexual dating couples and strangers.

Contrary to the notion that positive verbal responses reinforce behavior, research on physical pleasuring has demonstrated that positive verbal responsiveness from a recipient of pleasurable vibrations inhibits, rather than facilitates, heterosexual pleasuring. The present research examined the role of recipient responsiveness in interpersonal pleasuring through comparison of established dating couples with ad hoc pairs. Using the pleasure paradigm developed by the 1st author et al (1976), 160 undergraduate couples—either established dates or ad hoc pairs—delivered intensity-graded pleasurable vibrations to the buttocks and thighs of a recipient. It was predicted that among dating couples, intimacy would be perceived as appropriate; hence, responsiveness would facilitate rather than inhibit pleasuring. In the case of strangers, however, it was expected that intimacy would be perceived as inappropriate; hence, responsiveness would not facilitate pleasuring. Results support the predictions. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of the nycthemeral cycle of behavioural temperature regulation in man

1. Four human subjects were rendered hyperthermic and hypothermic by immersion in warm and cool water, at 02.00, 08.00, 14.00 and 20.00 hr. Bath and oesophageal temperatures and pulse rate were recorded. Temperature preference was determined by operant behaviour and vote. The core temperature set-point for behavioural thermoregulation was estimated from the behavioural results. 2. The results are in accord with those of previous studies of the nyethemeral cycling of autonomic responsiveness to heat and cold with a heating up phase before noon and a cooling down phase during the early night. 3. Subjective sensations and behavioural responses were also found to follow a nycthemeral cycle with a minimum before noon and a maximum at 20.00 hr. 4. The core temperature set point was 0-7 degrees C higher after noon than before noon with a small phase advance from resting core temperature. This result suggests that the nycthemeral cyclic change in body temperature is due to a nycthemeral cyclic change in the set-point near to which body temperature is kept by both autonomic and behavioural thermoregulatory responses.     

Skin signs in the diagnosis of thallium poisoning

OBJECTIVES: We sought to determine the cost advantage of a strategy of same-sitting diagnostic catheterization and percutaneous transluminal coronary angioplasty (PTCA) (ad hoc) in comparison with staged PTCA. BACKGROUND: It is widely assumed that an ad hoc strategy lowers costs by reducing the length of hospital stay (LOS). However, this assumption has not been examined in a contemporary data set. METHODS: We studied 395 patients undergoing PTCA during 6 consecutive months. Cost analysis was performed using standard cost-accounting methods and a mature cost-accounting system. Costs were examined within three clinical strata based on the indication for PTCA (stable angina, unstable angina and after myocardial infarction [MI]). RESULTS: For the entire patient cohort, there was no significant cost advantage of an ad hoc approach within any of the strata, although there was a nonsignificant trend toward an ad hoc approach in patients with stable angina. For patients treated with conventional balloon PTCA alone, the lack of a significant difference between ad hoc and staged strategies persisted. For patients who received stents, there was a significant cost advantage of an ad hoc approach in all three clinical strata. An important cost driver was the occurrence of complications. Differences in the rates of complications did not reach statistical significance between ad hoc and staged strategies, but even a small trend toward greater complications in patients who had the ad hoc strategy negated cost and LOS advantages. Our study had the power to detect significant cost differences of $1,300 for patients with stable angina, $2,100 for patients with unstable angina and $2,500 for post-MI patients. It is possible that we failed to detect smaller cost advantages as significant. CONCLUSIONS: A cost savings with an ad hoc strategy of PTCA could not be consistently demonstrated. The cost advantage of an ad hoc approach may be most readily realized in clinical settings where the intrinsic risks are low (e.g., stable angina) or in which the device used carries a reduced risk of complications (e.g., stenting), because even a small increase in the complication rate will negate any financial advantage of an ad hoc approach.     

实验测量轧制前滑值的误差分析

在实验轧机上测定了不同变形率下的滑值,并用同一数据源对前滑值进行了理论计算。针对前滑实测值与理论计算值之间的偏差,分析了其产生的原因,并提出了改进的措施。     

Thermoregulation in rats exposed perinatally to dioxin: core temperature stability to altered ambient temperature, behavioral thermoregulation, and febrile response to lipopolysaccharide

Recent studies have shown that perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) alters thermoregulatory function in adult rats and hamsters, indicated by a reduced body temperature during the animal's nocturnal phase. The present study was designed to assess the behavioral thermoregulation, ability to develop a fever, and thermoregulatory stability as a function of ambient temperature (Ta) in rats exposed perinatally to TCDD. Pregnant Long-Evans rats were exposed on gestational day (GD) 15 to 1 microg TCDD/kg (po). The male offspring were implanted with transmitters to monitor core temperature (Tc) and motor activity (MA). The 24-h pattern of core temperature was affected by TCDD exposure, characterized by a reduced nocturnal Tc. At some ages, the diurnal Tc of the TCDD group was elevated. This dysfunction in temperature regulation was most apparent at 7 and 11 mo of age. The 24-h pattern of MA was also altered by TCDD. The hypothermic effects of TCDD were most pronounced at cooler Ta values of 10 to 22 degrees C. In contrast, behavioral thermoregulation, assessed by measuring the selected Ta and Tc of rats in a temperature gradient, was unaffected by TCDD. The ability to develop a fever following administration of lipopolysaccharide (LPS) endotoxin (Escherichia coli; 50 microg/kg) was accentuated in the TCDD-treated animals. The data confirm a nocturnal hypothermia in rats prenatally exposed to TCDD. However, the normal behavioral regulation of Tc suggests that hypothalamic thermoregulatory centers are not permanently altered. The accentuated fever in TCDD animals shows possible functional alterations in the neuroimmune and/or thermoregulatory axes involved in fever.     

Categorization and metaphor understanding.

S. Glucksberg and B. Keysar (see record 1990-14310-001) have proposed a class-inclusion model of metaphor comprehension. This theory suggests that metaphors are not understood as implicit similes but are seen as class-inclusion statements in which the topic of a metaphor is assigned to a diagnostic, ad hoc category, whereas the metaphor's vehicle is a prototypical member of that category. The author claims that verbal metaphors are not simply instantiations of temporary, ad hoc categories but reflect preexisting conceptual mappings in long-term memory that are metaphorically structured. Various evidence from cognitive linguistics, philosophy, and psychology are described in support of this claim. Evidence is also presented that supports, contrary to Glucksberg and Keysar's position, the role of tacit conceptual metaphors in the comprehension of verbal metaphors in discourse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medical technology and cost containment: two applications of operations research

The government proposes "common sense" regulations to help contain rising health costs due to the increasing use of high-technology procedures, such as computerized tomography scanning. Two illustrations are given showing that such ad hoc regulations may have the effect of increasing costs and are certainly far from the optimum obtained by known methods of operations research.     

Thermoregulatory responses to cold transients: effects of menstrual cycle in resting women

Effects of the menstrual cycle on heat loss and heat production (M) and core and skin temperature responses to cold were studied in six unacclimatized female nonsmokers (18-29 yr of age). Each woman, resting supine, was exposed to a cold transient (ambient temperature = mean radiant temperature = 20 to -5 degrees C at -0.32 degrees C/min, relative humidity = 50 +/- 2%, wind speed = 1 m/s) in the follicular (F) phase (days 2-6) and midluteal (L) phase (days 19-23) of her menstrual cycle. Clothed in each of two ensembles with different thermal resistances, women performed multiple experiments in the F and L phases. Thermal resistance was 0.2 and 0.4 m2 . K . W-1 for ensembles A and B, respectively. Esophageal temperature (Tes), mean weighted skin temperature (Tsk), finger temperature (Tfing), and area-weighted heat flux were recorded continuously. Rate of heat debt (-S) and integrated mean body temperature (Tb,i) were calculated by partitional calorimetry throughout the cold ramp. Extensive peripheral vasoconstriction in the F phase during early periods of the ramp elevated Tes above thermoneutral levels. Shivering thermogenesis (DeltaM = M - Mbasal, W /m2) was highly correlated with declines in Tsk and Tfing (P <0.0001). There was a reduced slope in M as a function of Tb,i in the L phase with ensembles A (P < 0.02) and B (P < 0.01). Heat flux was higher and -S was less in the L phases with ensemble A (P < 0.05). An analytic model revealed that Tsk and Tes contribute as additive inputs and Tfing has a multiplicative effect on the total control of DeltaM during cold transients (R2 = 0.9). Endogenous hormonal levels at each menstrual cycle phase, core temperature and Tsk inputs, vascular responses, and variations in body heat balance must be considered in quantifying thermoregulatory responses in women during cold stress.     

Thermoregulatory vasoconstriction impairs active core cooling

BACKGROUND: Many clinicians now consider hypothermia indicated during neurosurgery. Active cooling often will be required to reach target temperatures < 34 degrees C sufficiently rapidly and nearly always will be required if the target temperature is 32 degrees C. However, the efficacy even of active cooling might be impaired by thermoregulatory vasoconstriction, which reduces cutaneous heat loss and constrains metabolic heat to the core thermal compartment. The authors therefore tested the hypothesis that the efficacy of active cooling is reduced by thermoregulatory vasoconstriction. METHODS: Patients undergoing neurosurgical procedures with hypothermia were anesthetized with either isoflurane/nitrous oxide (n = 13) or propofol/fentanyl (n = 13) anesthesia. All were cooled using a prototype forced-air cooling device until core temperature reached 32 degrees C. Core temperature was measured in the distal esophagus. Vasoconstriction was evaluated using forearm minus fingertip skin-temperature gradients. The core temperature triggering a gradient of 0 degree C identified the vasoconstriction threshold. RESULTS: In 6 of the 13 patients given isoflurane, vasoconstriction (skin-temperature gradient = 0 degrees C) occurred at a core temperature of 34.4 +/- 0.9 degree C, 1.7 +/- 0.58 h after induction of anesthesia. Similarly, in 7 of the 13 patients given propofol, vasoconstriction occurred at a core temperature of 34.5 +/- 0.9 degree C, 1.6 +/- 0.6 h after induction of anesthesia. In the remaining patients, vasodilation continued even at core temperatures of 32 degrees C. Core cooling rates were comparable in each anesthetic group. However, patients in whom vasodilation was maintained cooled fastest. Patients in whom vasoconstriction occurred required nearly an hour longer to reach core temperatures of 33 degrees C and 32 degrees C than did those in whom vasodilation was maintained (P < 0.01). CONCLUSIONS: Vasoconstriction did not produce a full core temperature "plateau," because of the extreme microenvironment provided by forced-air cooling. However, it markedly decreased the rate at which hypothermia developed. The approximately 1-h delay in reaching core temperatures of 33 degrees C and 32 degrees C could be clinically important, depending on the target temperature and the time required to reach critical portions of the operation.     

Norm theory: Comparing reality to its alternatives.

Presents a theory of norms and normality and applies the theory to phenomena of emotional responses, social judgment, and conversations about causes. Norms are assumed to be constructed ad hoc by recruiting specific representations. Category norms are derived by recruiting exemplars. Specific objects or events generate their own norms by retrieval of similar experiences stored in memory or by construction of counterfactual alternatives. The normality of a stimulus is evaluated by comparing it with the norms that it evokes after the fact, rather than to precomputed expectations. Norm theory is applied in analyses of the enhanced emotional response to events that have abnormal causes, of the generation of predictions and inferences from observations of behavior, and of the role of norms in causal questions and answers. (3 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhythms of temperature selection and body temperature are out of phase in the golden hamster.

Body temperature, locomotor activity, and thermoregulatory behavior of freely moving golden hamsters maintained in a spatial thermocline were measured over several weeks. The thermoregulatory behavior of temperature selection exhibited a robust daily rhythm 180° out of phase with the rhythms of body temperature and locomotor activity. However, the parameters of the body temperature rhythm (rhythmicity, mean level, and amplitude) were not significantly affected by the thermoregulatory behavior. Although the observed phase difference between the rhythms of temperature selection and body temperature might suggest that thermoregulatory behavior is modulated to oppose (rather than to defend) the rhythm of body temperature, the absence of effect of temperature selection on the parameters of the body temperature rhythm fails to reveal the physiological significance of such opposition. Further studies are necessary to establish the physiological significance of the rhythm of temperature selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

退火温度对S700MC强化效果的影响

采用退火试验,结合光学显微镜、扫描电镜、透射电镜和显微硬度计等设备,研究了不同退火温度对S700MC强化效果的影响。结果表明,退火处理能够显著影响碳化物形貌及变形区补充析出的细小铌和钛复合相的尺寸及分布。随着退火温度升高,碳化物及变形区补充析出的铌和钛复合相细化,弥散度提高,试样厚度方向上各检测位置的维氏硬度增大,强化效果显著;当退火温度升高至570 ℃时,碳化物及变形区补充析出的铌和钛复合相粗化,强化效果下降;而当退火温度为510 ℃ 时强化效果最佳。     

退火温度对S700MC强化效果的影响

采用退火试验,结合光学显微镜、扫描电镜、透射电镜和显微硬度计等设备,研究了不同退火温度对S700MC强化效果的影响。结果表明,退火处理能够显著影响碳化物形貌及变形区补充析出的细小铌和钛复合相的尺寸及分布。随着退火温度升高,碳化物及变形区补充析出的铌和钛复合相细化,弥散度提高,试样厚度方向上各检测位置的维氏硬度增大,强化效果显著;当退火温度升高至570 ℃时,碳化物及变形区补充析出的铌和钛复合相粗化,强化效果下降;而当退火温度为510 ℃ 时强化效果最佳。