Blood Pressure and Heart Rate Changes Accompanying Classical Eyeblink Conditioning In The Rabbit (Oryctolagus Cuniculus)

In two experiments employing 38 rabbits differential classical conditioning of heart rate, blood pressure, and corneoretinal potential (CRP) response were examined using l-sec and 4-sec interstimulus intervals ISI respectively. The conditioned response consisted of HK decelerations and DP depressor responses early in conditioning. However, many, but not all, animals revealed pressor responses and HR accelerations after the CRP discrimination was acquired. Significant correlations were also obtained between BP pressor responses, HR accelerations, and the frequency of CRP CRs. These results were discussed within the context of the orienting and defense reflexes.     

The Relationship Between Cardiac Activity and Sensory Acuity

The relationship between cardiac activity and sensory acuity suggested by Lacey and Lacey was tested by recording heart rates of Ss attempting to detect a threshold-level visual stimulus. Heart rate decelerations during a warning tone preceding the threshold stimulus were found in be greater on hit trials than on miss trials, supporting the suggested relationship.     

中晚期重型乙型肝炎血浆置换与内科治疗生存率的比较

观察血浆置换、内科治疗对中晚期重型乙型病毒性肝炎生存率的影响,探索中晚期重型肝炎的治疗方法。方法观察在内科治疗基础上给予血浆置换患者的肝功能、并发症及疾病的转归,与同期仅予内科综合治疗的患者相比较,对相应的临床资料进行统计学分析,从而了解两种治疗方法的疗效。结果血浆置换组36例,18例好转、18例死亡,内科治疗组32例,13例好转、19例死亡,两组之间患者生存情况无统计学差异;肝功能指标(ALT、AST、SB、ALB、TC、ChE和凝血酶原时间(PT)也无统计学差异。结论与内科治疗相比较,在其基础上给予血浆置换并不能提高中晚期重型病毒性肝炎生存率;中晚期重型肝炎患者的预后决定于其肝功能衰竭的程度。     

Using linked markers to infer the age of a mutation

Advances in sequencing and genotyping technologies over the last decade have enabled geneticists to easily characterize genetic variation at the nucleotide level. Hundreds of genes harboring mutations associated with genetic disease have now been identified by positional cloning. Using variation at closely linked genetic markers, it is possible to predict the times in the past at which particular mutations arose. Such studies suggest that many of the rare mutations underlying human genetic disorders are relatively young. Studies of variation at genetic markers linked to particular mutations can provide insights into human geographic history, and historical patterns of natural selection and disease, that are not available from other sources. We review two approaches for estimating allele age using variation at linked genetic markers. A phylogenetic approach aims to reconstruct the gene tree underlying a sample of chromosomes carrying a particular mutation, obtaining a “direct” estimate of allele age from the age of the root of this tree. A population genetic approach relies on models of demography, mutation, and/or recombination to estimate allele age without explicitly reconstructing the gene tree. Phylogenetic methods are best suited for studies of ancient mutations, while population genetic methods are better suited for studies of recent mutations. Methods that rely on recombination to infer the ages of alleles can be fine‐tuned by choosing linked markers at optimal map distances to maximize the information available about allele age. A limitation of methods that rely on recombination is the frequent lack of a fine‐scale linkage map. Maximum likelihood and Bayesian methods for estimating allele age that rely on intensive numerical computation are described, as well as “composite” likelihood and moment‐based methods that lead to simple estimators. The former provide more accurate estimates (particularly for large samples of chromosomes) and should be employed if computationally practical. Hum Mutat 18:87–100, 2001. © 2001 Wiley‐Liss, Inc.     

The effects of amrinone and glucagon on verapamil-induced cardiovascular toxicity in anaesthetized rats

The goal of this study was to compare the effects of glucagon and amrinone on mean arterial pressure (MAP) and heart rate, when used alone and in combination, in an anaesthetized rat model of verapamil toxicity. Rats were anaesthetized and the carotid artery was cannulated for MAP and heart rate measurements. Jugular and femoral veins were cannulated for drug administration. After verapamil infusion (15 mg/kg/h), control animals were given normal saline solution and the other groups received amrinone (0.1 or 0.2 mg/kg/min), glucagon (0.3 mg/kg bolus followed by 0.1 or 0.2 mg/kg/min infusion), glucagon plus amrinone (0.1 mg/kg/min and 0.1 mg/kg/min respectively) or glucagon plus amrinone (0.2 mg/kg/min and 0.1 mg/kg/min respectively). Glucagon (0.2 mg/kg/min) significantly increased MAP when compared to the control group ( P  < 0.01). The combination of glucagon and amrinone did not produce a synergistic effect for the recovery of MAP. Furthermore, this combination masked the positive effects of glucagon (0.2 mg/kg/min) on MAP.Glucagon (0.2 mg/kg/min) increased the heart rates compared with those of the control group ( P  < 0.05). Additionally, amrinone (0.1 mg/kg/min) plus glucagon (0.1 mg/kg/min) increased the heart rates ( P  < 0.05). Finally, glucagon dose dependently recovered MAP. While amrinone depressed MAP in combination with glucagon, it did not alter the positive chronotropic effect of high dose glucagon.     

Interaction of a Motor Response, and Reaction Time and Time Estimation Tasks, on Heart Rate and Skin Conductance

The influence of motor responding and typical psychophysiological tasks on heart rate was tested by manipulating motor requirements of reaction time (RT) and time estimation (TE) tasks. Thirty-four volunteers were assigned randomly to four groups. Two groups squeezed a hand dynamometer at the start of a trial and the other two groups squeezed at the finish of the trial. The force of the squeeze was also manipulated: either 3 kg (3) or 7 kg (7). The four groups were Start 3, Start 7, Finish 3, and Finish 7. All subjects participated in the TE and RT tasks. The dependent variables were measurements of forearm flexor muscle tension, heart rate and skin conductance. It was found that the manipulations of when and with what force a person squeezed the dynamometer resulted in reliable group differences in muscle tension. The magnitude of acceleratory components of the triphasic (acceleration-deceleration-acceleration) cardiac response was amplified by tension. The magnitude of the deceleratory component seemed to depend on both muscle tension and stimulus processing. Except for the magnitude of the response-bound deceleration, RT and TE produced very similar heart rate responses, and skin conductance did not differ among groups. The data were interpreted as providing evidence that motor response acts as an amplifier for the phasic HR produced by common psychological paradigms.     

Effect of aerobic capacity on sweat rate and fluid intake during outdoor exercise in the heat

We measured the aerobic capacity, sweat rate and fluid intake of trained athletes during outdoor exercise and examined the relationship between aerobic capacity and thermoregulatory responses at high ambient temperatures. The maximal aerobic capacity ( ) of the subjects, nine male baseball players of college age, was determined by maximal exercise tests on a cycle ergometer. The subjects practised baseball regularly without drinking fluids from 1330 to 1530 hours. After 30 min rest, they played a baseball game with free access to a sports drink at 15°C from 1600 to 1830 hours. At a mean ambient temperature of 36.7 (SEM 0.2)°C, the mean percentage of body mass loss (m _b) and increase of oral temperature (T _o) from 1330 to 1530 hours was 3.47 (SEM 0.12)% and 0.81 (SEM 0.14)°C, respectively. The sweat loss from 1330 to 1830 hours was 56.53 (SEM 1.56)ml · kg^–1 of body mass (M _b) while the mean fluid consumption was 44.78 (SEM 2.39)ml · kg^–1 ofm _b, with recovery of 76.08 (SEM 2.81)% of sweat loss. The was significantly inversely correlated withm _b, fluid intake and rehydration amount, but showed no correlation withT _o. These results would suggest that at a given exercise intensity in subjects with a higher aerobic capacity body temperature is maintained with a lower sweating rate than that in subjects with a lower aerobic capacity.     

Determination of specific oxygen uptake rates in human hematopoietic cultures and implications for bioreactor design

Oxygen plays an important role in the cultivation of primary cellsex vivo. In this study, we used hermetically sealed tissue culture well inserts equipped with oxygen electrodes to measure the oxygen utilization of cultured human bone marrow mononuclear cells (BM MNCs). The oxygen uptake rate (OUR) of BM MNCs was determined during a 14-day culture in which both adherent and nonadherent cells were present. Early in the culture, the cells exhibited very low OURs. The specific OURs (uptake rate per cell) were at approximately 0.005 μmol/10⁶ cells/hr shortly after the initiation of culture. The OUR then increased as the cultures developed. After about 8 to 10 days of cultivation the specific OURs had increased to 0.038±0.006 and 0.025±0.005 μmol/10⁶ cells/hr for adherent and nonadherent cells, respectively, after which no further increase was observed. Based on these oxygen uptake rate data, a mathematical model of oxygen diffusion was formulated and use to investigate issues associated with hematopoietic bioreactor design, including initial cell density, medium depth, reactor configuration, and oxygen partial pressure.In situ OUR measurements confirmed predicted oxygen limitations based on the mathematical model and the experimentally determined OURs. High-density hematopoietic cultures present design challenges in terms of sufficient and uniform delivery of oxygen to an active hematopoietic culture. These challenges can be met by using parallelplate bioreactors with thin liquid layers.     

An Attempt to Elk it Cardiac Orienting and Defense Responses in the Newborn to Two Types of Facial Stimulation

Cardiac and behavioral reactivity of the human newborn to facial stimulation eliciting approach and escape responses were compared in order to test the distinction between cardiac orienting and defensive reactions. Each infant received 8 trials each of check stimulation (stroking near the mouth) and ear stimulation (pinch on the ear lobe). HR response to both tactile stimuli were accelerations of different amplitude when motor responses were also present. When no overt behavioral response was observed, stroking on the check elicited cardiac deceleration while ear stimulation again elicited acceleration. Thus, cardiac orienting was demonstrated in newborns when a rooting stimulus was presented that did not elicit overt head turning. The HR response to ear stimulation on trials unaccompanied by observed movements was a larger acceleration than to cheek stimulation when movement was present. This finding suggests that movement itself does not produce the observed HR increase, but rather that central processing of the signal value of the stimulus determines both overt and cardiac responding.