Sister-chromatid exchanges in newborns after normal and progesterone-treated pregnancies

Two groups of newborns were selected for SCE analyses, one consisting of infants born after progesterone-treatment during pregnancy (PTP) and a control group. A slight, but statistically significant difference in the number of SCEs was found: in the control group 5.55 +/- 0.62, and in the PTP group 7.99 +/- 0.88. This effect also proved to be true in an in vitro system, where various concentrations of progesterone were tested. The authors offer two possible explanations: one involving the biochemical pathways of progesterone and the influence on the level of excretory products; the other involving a direct relationship between progesterone and DNA.     

The influence of foot position on body dynamics

During locomotion, the human body exhibits inherent dynamic properties such as mass (M), stiffness (K) and damping (B). During the gait cycle, foot contact with the ground progresses from the heel to the toe. Contact forces between the foot and ground are defined as ground reaction forces (GRF). It is unclear how body dynamics are affected by foot landing position. If the shape of GRF is indicative of body dynamics, our understanding of gait patterns in normal and pathologic conditions may improve. The aims of this study were to determine:(1) whether foot landing position affects the inherent dynamics of the human body and (2) the extent to which the GRF curve reflects the response of inherent body dynamics to sudden loading.Eight non-disabled control volunteers performed a series of small jumps and landed on one leg with a fully extended knee in three foot landing positions: heel, mid-foot, and toe. They then walked at self-paced velocity over force plates. For each foot landing position, values of K, B and the dimensionless damping coefficient, ξ, were calculated from the period of vertical body oscillations, T, and compared with an ANOVA test. In addition, the time between the two peaks of the vertical GRF, T_GRF, was compared with T. We found that that K and B decreased and ξ did not change (p<0.01) between heel to toe-landing positions. T_GRF was not different than T for the toe-landing position, which suggests that the dynamic body response has major impact on the shape of GRF.     

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

BACKGROUND: To 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. RESULTS: BOD PODFH %fat (27.1%) and body volume (61.5 L) were significantly lower (P 相似文献   

The influence of body position on maximal performance in cycling

Six healthy male subjects performed a 3-min supramaximal test in four different cycling positions: two with different trunk angles and two with different saddle-tube angles. Maximal power output and maximal oxygen uptake (VO2max) were measured. Maximal power output was significantly higher in a standard sitting (SS, 381 W, SD 49) upright position compared to all other positions: standard racing (SR, 364 W, SD 49), recumbent backwards (RB, 355 W, SD 44) and recumbent forwards (RF, 341 W, SD 54). Although VO2max was also highest in SS (4.31 l.min-1, SD 0.5) upright position, the differences in VO2max were not significant (SR, 4.2 l.min-1, SD 0.53; RB, 4.17 l.min-1, SD 0.58; RF, 4.11 l.min-1, SD 0.66). It is concluded that (supra)maximal tests on a cycle ergometer should be performed in a sitting upright position and not in a racing position. In some cases when cycling on the road, higher speeds can be attained when sitting upright. This is especially true when cycling uphill when high power must be generated to overcome gravity but the road speed, and hence the power required to overcome air resistance, is relatively low.     

Apparent latent heat of evaporation from clothing: attenuation and "heat pipe" effects.

Investigating claims that a clothed person's mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34 degrees C in ambient temperatures of 10, 20, and 34 degrees C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (E(mass)) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (E(app)) were compared. A clear discrepancy was observed. E(mass) overestimated E(app) in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34 degrees C, apparent latent heat (lambda(app)) of pure evaporative cooling was lower than the physical value (lambda; 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, lambda(app) increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, lambda(app) even exceeds lambda by four times that value at 10 degrees C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.     

The influence of body position on autonomic nervous system function

Five physiological measurements were recorded while 20 males Ss listened to a series of tones in two body positions (horizontal and vertical). Half the Ss were tested in the horizontal position, then raised to a vertical position. The other half were tested vertically first. The results showed body position significantly influenced basal levels for heart rate (HR), finger volume (FV), skin resistance (SR) and blood pressure (BP). In the vertical position, sympathetic arousal was higher than in the horizontal position. In addition, the sequence in which a S was tested influenced physiological activity in the two body positions. It was concluded that both resting levels and pretest activity levels are important variables to consider in research on physiological differences in psychiatric populations.     

Relationships between body movements and phase of respiratory cycle in newborns.

To determine the relationships between body movements and phase of the respiratory cycle, we performed polygraphic recordings during daytime sleep in 12 normal newborns: 6 premature infants of 31 to 36 weeks conceptional age and 6 full-term infants of 39-41 weeks conceptional age. Chin and eye movements, movements detected during sighs and body movements not related to sighs were analysed separately. We analysed 1838 chin and body movements with a clearly defined beginning. Data obtained were similar in both premature and full-term infants, without statistically significant differences when active and quiet sleep states were compared. We found that: (a) The 96 movements concomitant with sighs all started during inspiratory diaphragmatic bursts. (b) The 1270 body movements unrelated to sighs started predominantly (78.6% in premature infants, 81.3% in full-term infants) during expiration, after the end of diaphragmatic contraction (P less than 0.002). (c) The 472 chin movements and eye movements occurred randomly with respect to phases of respiration. In conclusion, our data show that central motor command level determines relationships between movement initiation and respiratory phase. They suggest inhibition of trunk and limb movements (under pyramidal control) during diaphragmatic contraction as early as 31 weeks CA. This inhibition is absent during sighs, which involve the inspiratory augmenting reflex, and does not apply to chin and eye movements, which are mediated by cranial nerves.     

The influence of mother's active smoking during pregnancy on body mass index of newborns

Many investigations have noted bad influence of smoking during pregnancy. In the present article, the influence of mothers smoking during pregnancy on the body mass index (BMI), birth weight and birth length are examined. This retrospective research included 219 children: Group I: 109 children from rural area of east Slavonia (born in General Hospital-Vinkovci) and group II: 110 children from industrial area (born in Zagreb). The questioned subjects were divided into two groups depending on mothers smoking during pregnancy: newborns of mothers who didn't smoke during pregnancy (subgroup A) and newborns of mother who did smoke 10 or more cigarettes per day during pregnancy (subgroup B). Anthropometric parameters (BMI, birth length and birth weight) in newborns of non-smoking mothers were statistically higher (p < 0.05) than in newborns of smoking mothers. Moderate correlation between birth length and birth weight in newborns of non-smoking and smoking mothers from rural area and from non-smoking mothers in urban area was statistically significant, but correlation in the group in newborns of smoking mothers from Zagreb was not statistically significant. Results of this research show that smoking during pregnancy significantly influences the birth weight and birth length. Further investigation is needed, to investigate the lack of correlation between the birth length and birth weight in newborns of smoking mothers from industrial city.     

Influence of head position on thermal stress in newborns: simulation using a thermal mannequin.

The influence of head position on thermal stress was assessed by using a heavily clothed thermal mannequin in three different body positions [supine, face straight up (FSU); supine, face to the side (FTS); prone, FTS] and with or without the head covered by a bonnet. The mannequin was exposed to air temperatures of 29, 32, 34, and 36 degrees C. When the head is uncovered, body or head position has no impact on heat loss. When the head is covered, dry heat loss from the mannequin as a whole (and that from the head in particular) is lower (-0.35 to -0.40 W) in the FTS position than in the FSU position as a result of decreased heat loss from the surface area of the face in contact with the mattress. In the FTS position and with the head covered, there was no difference in heat loss between the prone and supine positions. The results suggest that in heavily clothed newborns whose head is covered by a bonnet, thermal stress depends on the head position.     

Lipodissection in body sculpturing: the dry procedure

We have used the honeycombed suction lipectomy (wet and/or dry) in over 700 patients. It represents a major advancement in the treatment of the localized adiposities of the body. Its advantages are eliminating the need for long, unsightly scars and reducing operating time and morbidity. Selection of appropriate patients is of paramount importance for reliable results because this technique is truly sculpting of the soft tissues. Results improve also with the proper training and experience of the surgeon. The indications and complications have been discussed. This technique (honeycombed suction lipectomy) appears more reliable than suction curettage that employs sharp dissection.     

Longitudinal distribution of canine respiratory heat and water exchanges

We assessed the longitudinal distribution of intra-airway heat and water exchanges and their effects on airway wall temperature by directly measuring respiratory fluctuations in airstream temperature and humidity, as well as airway wall temperature, at multiple sites along the airways of endotracheally intubated dogs. By comparing these axial thermal and water profiles, we have demonstrated that increasing minute ventilation of cold or warm dry air leads to 1) further penetration of unconditioned air into the lung, 2) a shift of the principal site of total respiratory heat loss from the trachea to the bronchi, and 3) alteration of the relative contributions of conductive and evaporative heat losses to local total (conductive plus evaporative) heat loss. These changes were not accurately reflected in global measurements of respiratory heat and water exchange made at the free end of the endotracheal tube. Raising the temperature of inspired dry air from frigid to near body temperature principally altered the mechanism of airway cooling but did not influence airway mucosal temperature substantially. When local heat loss was increased from both trachea and bronchi (by increasing minute ventilation), only the tracheal mucosal temperature fell appreciably (up to 4.0 degrees C), even though the rise in heat loss from the bronchi about doubled that in the trachea. Thus it appears that the bronchi are better able to resist changes in airway wall temperature than is the trachea. These data indicate that the sites, magnitudes, and mechanisms of respiratory heat loss vary appreciably with breathing pattern and inspired gas temperature and that these changes cannot be predicted from measurements made at the mouth. In addition, they demonstrate that local heat (and presumably, water) sources that replenish mucosal heat and water lost to the airstream are important in determining the degree of local airway cooling (and presumably, drying).     

Mathematical prediction of core body temperature from environment,activity, and clothing: The heat strain decision aid (HSDA)

Physiological models provide useful summaries of complex interrelated regulatory functions. These can often be reduced to simple input requirements and simple predictions for pragmatic applications. This paper demonstrates this modeling efficiency by tracing the development of one such simple model, the Heat Strain Decision Aid (HSDA), originally developed to address Army needs. The HSDA, which derives from the Givoni-Goldman equilibrium body core temperature prediction model, uses 16 inputs from four elements: individual characteristics, physical activity, clothing biophysics, and environmental conditions. These inputs are used to mathematically predict core temperature (T_c) rise over time and can estimate water turnover from sweat loss. Based on a history of military applications such as derivation of training and mission planning tools, we conclude that the HSDA model is a robust integration of physiological rules that can guide a variety of useful predictions. The HSDA model is limited to generalized predictions of thermal strain and does not provide individualized predictions that could be obtained from physiological sensor data-driven predictive models. This fully transparent physiological model should be improved and extended with new findings and new challenging scenarios.