Thermal manipulations of turkey embryos: The effect on thermoregulation and development during embryogenesis.

Previous studies conducted on meat-type chickens in our laboratory showed that thermal manipulations (TMS:) of the embryo during the time window of the hypothalamus-hypophysis-thyroid axis development and maturation significantly reduced the metabolic rates of the embryo and the chicken, improving the posthatch feed conversion rate (FCR:). The aim of the present study was to investigate the effect of intermittent TMs during turkey embryogenesis on embryo development. Fertile turkey eggs were divided into three treatments: control; 6H--with TM by elevation of temperature and RH by 1.7°C and 9%, respectively, above the control conditions for 6 h/d, from E10 through E22, i.e., 240 through 552 h of incubation; and 12H--with TM as above, for 12 h/d, during the same time period. From E0 through E10 and from E23 onward all eggs were incubated under control conditions. The embryo growth rate was not negatively affected by TM. During TM eggshell temperature, the embryonic heart rate and oxygen consumption were elevated by the manipulation while the embryos were in their ectothermic phase. However, by the end of the TM period and until hatch (the endothermic phase) these parameters were significantly lower in both TM treatments than in the control, indicating a lower metabolic rate and heat production. The TM embryos hatched approximately 10 h earlier than the controls, without any negative effects on chick body weight or hatchability. Nevertheless, TM treatments resulted in a higher proportion of chicks with unhealed navels. Body temperature at hatch was significantly lower in the TM chicks than in the controls, suggesting lower heat production and metabolic rate, which might affect the energy requirements for posthatch maintenance. It was concluded that TM during turkey embryogenesis might have altered the thermoregulatory set point, and thus lowered the embryo metabolic rate, which might have a long-lasting posthatch effect.

Review of the criterion-related validity of the WISC-III: the first five years.

A review of studies comparing the WISC-III to other measures of intelligence and achievement indicates the revision is continuing to meet the standards established by its predecessor, the WISC-R. Correlations are substantial, both for measures of ability and achievement; however, compared to the WISC-R, the WISC-III Full Scale IQ tends to be about six points lower, probably reflecting the "Flynn effect" (1984). As a consequence, eligibility for programs in special education may be negatively affected.

Evaluation of heart rate changes: electrocardiographic versus photoplethysmographic methods.

The heart rate (HR) variation to forced deep breathing (HRDB) and to the Valsalva maneuver (Valsalva ratio; VR) are the two most widely used tests of cardiovagal function in human subjects. The HR is derived from a continuously running electrocardiographic (ECG) recording. Recently, HR derived from the arterial waveform became available on the Finapres device (FinapHR), but its ability to detect rapid changes in HR remains uncertain. We therefore evaluated HRDB and VR derived from FinapHR using ECG-derived HR (ECGHR) recordings as the standard. We also compared the averaged HR on Finapres (Finapav) with beat-to-beat Finapres (FinapBB) values. Studies were undertaken in 12 subjects with large HR variations: age, 34.5 +/- 9.3 (SD) years; six males and six females. FinapBB values were superimposable upon ECGHR for both HRDB and VR. In contrast, Finapav failed to follow ECGHR for HRDB and followed HRECG with a lag for the VR. To evaluate statistically how closely FinapHR approximated ECGHR, we undertook regression analysis, using mean values for each subject. To compare the two methods, we evaluated the significance of the difference between test and standard values. For HRDB, FinapBB reproducibly recorded HR (R2 = 0.998), and was significantly (p = 0.001) better than Finapav (R2 = 0.616; p < 0.001). For VR, HRBB generated a VR that was not significantly different from the correct values, while HRav generated a value that was slightly but consistently lower than the correct values (p < 0.001). We conclude that FinapHR reliably records HR variations in the beat-to-beat mode for cardiovascular HR tests.

A standard test of heat-pain responses using CASE IV.

Heat-pain threshold and stimulus response characteristics can be evaluated with graduated heating pulses from a radiant heat source or a contact thermode. Results may be used to: (1) evaluate differences in sensation among anatomical sites, sides of the body, and with development and aging; and (2) provide an end-point for the study of the efficacy of drugs; or to follow the course of sensory alteration in disease (medical practice, epidemiologic studies, and controlled clinical trials). Because there is great variability in how tests of this kind are performed and scored, comparisons of results among medical centers are difficult. To meet this need, we have developed, and here describe, a standardized and validated test of heat-pain. We use both pyramidal and trapezoid-shaped stimuli. The range of stimulus magnitudes we recommend is sufficient to test heat-pain at a sensitive region (the face) of young people and an insensitive region (the foot) of healthy old people. From tests on healthy subjects and patients, we find that neither our previously published forced-choice or 4, 2, and 1 stepping algorithms are suitable for testing heat-pain sensation. We, therefore, introduce the Non-Repeating Ascending with Null Stimuli (NRA-NS) algorithm which performs satisfactorily. The graphed data points of responses to increasingly stronger heat pulses were made up of two components-the no pain (0) response line and the heat-pain response line (> or = 1 numerical scaling of the pain responses graded from 1 [least] to 10 [greatest]). For the pain responses, we found that usually a curve could be fit using a quadratic equation. Using this equation, or interpolation where necessary, it is possible to compute the heat-pain detection threshold (HPDT or HP:0.5), an intermediate heat-pain response (HP:5.0), and the difference between the two (HP:5.0-0.5). Our studies show that a certain time is needed between successive stimuli and tests to minimize changing basal skin temperature or threshold. We also demonstrated that low or high baseline skin temperatures can affect heat-pain responses, therefore, we advocate specific testing conditions. Based on a study of 25 healthy subjects, the reproducibility of the test falls within +/-1 stimulus steps 88% of the time for HP:5.0 and 76% of the time for HP:0.5. The precise approaches employed to make the test standard and reproducible are described. We illustrate that the algorithm and testing system is able to document altered pain threshold with skin abrasion, with intradermal injection of nerve growth factor, and with diabetic polyneuropathy.

Taste perception of monosodium glutamate (MSG) in foods in young and elderly subjects.

The purpose of this study was to determine the concentrations at which young and elderly subjects were able to detect and recognize monosodium glutamate (MSG) and MSG with 0.5 mM inosine-5'-monophosphate (IMP) in various food media including meats, vegetables, and soups. The most preferred concentration levels of MSG and MSG (with IMP) in the foods were also determined. Detection thresholds for MSG (with IMP) in foods were elevated in elderly subjects compared with young subjects. The detection thresholds for elderly subjects for MSG with IMP in foods were an average of 2.8 times higher than the same detection thresholds for young subjects. The variability among subjects in the ability to detect MSG (with or without IMP) in every food was far greater than the variability found previously in water solutions, especially for young subjects. Adding 0.5 mM IMP to the MSG did not significantly affect detection thresholds in foods. However, preference scores of both young and elderly subjects were significantly higher for the MSG with IMP condition than the MSG alone condition for some foods. Optimally preferred concentration levels of MSG in foods tended to be lower than the level at which MSG is detected or recognized in the food but above the detection threshold for MSG in water. The mechanism by which MSG can be preferred at a subthreshold concentration in foods is not fully understood. One possibility is that MSG synthesizes with food chemicals and forms a new taste quality.

The algorithmic complexity of neural spike trains increases during focal seizures.

The interspike interval spike trains of spontaneously active cortical neurons can display nonrandom internal structure. The degree of nonrandom structure can be quantified and was found to decrease during focal epileptic seizures. Greater statistical discrimination between the two physiological conditions (normal vs seizure) was obtained with measurements of context-free grammar complexity than by measures of the distribution of the interspike intervals such as the mean interval, its standard deviation, skewness, or kurtosis. An examination of fixed epoch data sets showed that two factors contribute to the complexity: the firing rate and the internal structure of the spike train. However, calculations with randomly shuffled surrogates of the original data sets showed that the complexity is not completely determined by the firing rate. The sequence-sensitive structure of the spike train is a significant contributor. By combining complexity measurements with statistically related surrogate data sets, it is possible to classify neurons according to the dynamical structure of their spike trains. This classification could not have been made on the basis of conventional distribution-determined measures. Computations with more sophisticated kinds of surrogate data show that the structure observed using complexity measures cannot be attributed to linearly correlated noise or to linearly correlated noise transformed by a static monotonic nonlinearity. The patterns in spike trains appear to reflect genuine nonlinear structure. The limitations of these results are also discussed. The results presented in this article do not, of themselves, establish the presence of a fine-structure encoding of neural information.

Cool, warm, and heat-pain detection thresholds: testing methods and inferences about anatomic distribution of receptors.

We recently found that vibratory detection threshold is greatly influenced by the algorithm of testing. Here, we study the influence of stimulus characteristics and algorithm of testing and estimating threshold on cool (CDT), warm (WDT), and heat-pain (HPDT) detection thresholds. We show that continuously decreasing (for CDT) or increasing (for WDT) thermode temperature to the point at which cooling or warming is perceived and signaled by depressing a response key ("appearance" threshold) overestimates threshold with rapid rates of thermal change. The mean of the appearance and disappearance thresholds also does not perform well for insensitive sites and patients. Pyramidal (or flat-topped pyramidal) stimuli ranging in magnitude, in 25 steps, from near skin temperature to 9 degrees C for 10 seconds (for CDT), from near skin temperature to 45 degrees C for 10 seconds (for WDT), and from near skin temperature to 49 degrees C for 10 seconds (for HPDT) provide ideal stimuli for use in several algorithms of testing and estimating threshold. Near threshold, only the initial direction of thermal change from skin temperature is perceived, and not its return to baseline. Use of steps of stimulus intensity allows the subject or patient to take the needed time to decide whether the stimulus was felt or not (in 4, 2, and 1 stepping algorithms), or whether it occurred in stimulus interval 1 or 2 (in two-alternative forced-choice testing). Thermal thresholds were generally significantly lower with a large (10 cm2) than with a small (2.7 cm2) thermode.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of algorithms of testing for use in automated evaluation of sensation.

Estimates of vibratory detection threshold may be used to detect, characterize, and follow the course of sensory abnormality in neurologic disease. The approach is especially useful in epidemiologic and controlled clinical trials. We studied which algorithm of testing and finding threshold should be used in automatic systems by comparing among algorithms and stimulus conditions for the index finger of healthy subjects and for the great toe of patients with mild neuropathy. Appearance thresholds obtained by linear ramps increasing at a rate less than 4.15 microns/sec provided accurate and repeatable thresholds compared with thresholds obtained by forced-choice testing. These rates would be acceptable if only sensitive sites were studied, but they were too slow for use in automatic testing of insensitive parts. Appearance thresholds obtained by fast linear rates (4.15 or 16.6 microns/sec) overestimated threshold, especially for sensitive parts. Use of the mean of appearance and disappearance thresholds, with the stimulus increasing exponentially at rates of 0.5 or 1.0 just noticeable difference (JND) units per second, and interspersion of null stimuli, Békésy with null stimuli, provided accurate, repeatable, and fast estimates of threshold for sensitive parts. Despite the good performance of Békésy testing, we prefer forced choice for evaluation of the sensation of patients with neuropathy.

The effect of aging on cardiac autonomic and postganglionic sudomotor function.

Little quantitative information is available on the effects of age on peripheral autonomic function. We studied the effect of age on the heart rate (HR) responses to deep breathing and the Valsalva maneuver in 122 and 155 subjects, respectively, aged 10 to 83 years. The quantitative sudomotor axon reflex test (QSART) was determined in 114 subjects in the same age group. The HR responses were not different between the sexes, but a consistently significant regression with age was demonstrated in response to deep breathing and the Valsalva ratio. The QSART responses were significantly larger in male subjects and were generally lower in older subjects of both sexes but a significant negative regression with age was found only in female subjects. Cardiac vagal function is impaired with age, but postganglionic sympathetic function is little affected by age, suggesting selectivity of effects of aging on autonomic function.

Saltatory transitions are a naturally occurring property of evolving systems.

On the basis of paleological evidence, it has been suggested that biological evolution need not necessarily be characterized by gradual change. Rather, evolutionary history may display saltatory periods of rapid speciation alternating with periods of relative quiescence, the whole dynamic being called punctuated equilibria. The empirical evidence that has been presented in support of this hypothesis has been the object of a vigorous dispute. Mathematical investigations of complex models of biological evolution that contain random elements have demonstrated that these systems can display saltatory behavior. In this paper we address a more abstract question: can saltations occur in the evolution of very simple, deterministic mathematical systems that function in a constant environment? The answer appears to be yes. Saltations appear as a natural dynamical behavior in the evolution of simplistic information processing networks. We stress that these networks do not constitute a model of biological evolution. However, the appearance of saltations in such simple systems suggests that their appearance in a process as complex as biological evolution is not surprising.

Dynamics of brain electrical activity.

In addition to providing important theoretical insights into chaotic deterministic systems, dynamical systems theory has provided techniques for analyzing experimental data. These methods have been applied to a variety of physical and chemical systems. More recently, biological applications have become important. In this paper, we report applications of one of these techniques, estimation of a signal's correlation dimension, to the characterization of human electroencephalographic (EEG) signals and event-related brain potentials (ERPs). These calculations demonstrate that the magnitude of the technical difficulties encountered when attempting to estimate dimensions from noisy biological signals are substantial. However, these results also suggest that this procedure can provide a partial characterization of changes in cerebral electrical activity associated with changes in cognitive behavior that complements classical analytic procedures.

The use of fibrin adhesive in the repair of chondral and osteochondral injuries.

Fibrin adhesive proved to be useful in the reattachment of chondral and osteochondral fragments. Its use is based on sound biological principles. It offers a number of advantages over internal fixation; it causes no further damage to the cartilage, even small chondral fragments can be reattached and a second operation for the removal of metalwork is unnecessary. Its bonding strength provides only contact stability, so that immobilization in plaster for 3 weeks is always necessary. In the last 5 years we have used fibrin adhesive in 28 patients for the fixation of 39 chondral or osteochondral fragments. Of these, 26 cases were followed up for periods of 6 months to 5 years. Twelve patients were examined arthroscopically; 9 of them showed complete healing of the fragments, and only 3 slight localized degenerative changes. In 15 cases we were able to see radiological healing. All except two showed union of the fragments and restoration of the joint surface. In view of our results fibrin adhesive can be recommended for the operative management of cartilage injuries.

Sexual activity level and sexual functioning in women prenatally exposed to diethylstilbestrol.

Thirty women with a history of prenatal exposure to diethylstilbestrol (DES) underwent a detailed sexual history and were compared to a demographically similar sample of 30 women with a history of an abnormal Pap smear. The DES women were found to have less well-established sex-partner relationships and less experience with child-bearing, to be lower in sexual desire and enjoyment, sexual excitability, and orgasmic coital functioning, but to be comparable (and low) with regard to such sexual dysfunctions as vaginismus and dyspareunia. Both potential psychosocial and neuroendocrine explanations are discussed.

Sexual orientation after prenatal exposure to exogenous estrogen.

Thirty women aged 17 to 30 years with documented prenatal exposure to the nonsteroidal synthetic estrogen diethylstilbestrol (DES) were compared to thirty women of similar demographic characteristics from the same medical clinic who had a history of abnormal Pap smear findings. A subsample of the DES women were also compared to their DES-unexposed sisters. Sexual orientation in its multiple components was assessed by systematic semistructured interviews. In comparison to both control groups, the DES women showed increased bisexuality and homosexuality. However, about 75% of the DES women were exclusively or nearly exclusively heterosexual. Nonhormonal and hormonal interpretations of these findings are discussed.

Psychosexual milestones in women prenatally exposed to diethylstilbestrol.

Thirty women aged 17 to 30 years with a record-confirmed history of prenatal exposure to diethylstilbestrol (DES) were compared to 30 women of similar age and demographic background with a history of abnormal Pap smear findings. Heterosocial and heterosexual histories were assessed by systematic semistructured interviews. The groups differed neither in the age at menarche nor in the age at attainment of various psychosexual milestones.

Appearance of [3H]saxitoxin binding sites in developing rat brain.

The binding of [3H]saxitoxin to a crude membrane fraction from rat brains of various ages was determined. We found that at two days before birth, the maximum number of binding sites is 100 fmol/mg of membrane protein. This value increases rapidly for the two weeks following birth, eventually reaching a plateau value of about 800 fmol of toxin sites per mg protein. Since published reports indicate that rat brain myelination occurs primarily between days 15 and 21, we conclude that the development of sodium channels, as measured by [3H]saxitoxin binding, precedes myelination.

Parental work patterns in alternative families: influence on child development.

The increasing return to work by mothers of young children was documented for matching samples of mothers in families representing traditional marriages, single-mother units, social-contract relationships, and communal living groups. No evidence was found of negative effects on children's social, emotional, and cognitive development attributable to maternal absence due to employment.

Histamine release into tracheal lumen and bronchial reactivity. Effect of compound 48/80 administered by different routes in various doses on histamine release and bronchial reactivity.

The influence of tracheal lavage with compound 48/80 on the bronchial response to challenge with ACH and AE was studied in 24 animals. Furthermore, the effect of i.v. administration of 48/80 was compared to its administration into the tracheal lumen. No increased histamine liberation was detected in the tracheal fluid after lavage with 48/80, nor was an influence on the bronchial response observed. These observations were the same as those described for tracheal lavage with water. The same amounts of this secretagogue induced, after i.v. administration, a high histamine release which correlates significantly with blood pressure decrease.