Pharmacologic hemoglobin reversal: the importance of lipid intermediaries and the proposed involvement of the cAMP and phosphatidylinositol second messenger systems

Humoral and microenvironmental influences have played a major role in recent research into reversing the Hb F to Hb A switch. Early research in this area focused on hormonal influences and showed both thyroid hormone and prolactin could induce small but statistically significant reversals in hemoglobin phenotype. Recent research has focused on the effect of certain lipids in this process. The current study shows a synergy between thyroid hormone and prolactin in inducing a significant switch in adult rat hemoglobin patterns toward the neonatal pattern. Further, it is hypothesized that this synergy is due to the hormones' effect on lipid intermediaries whose effect in turn are proposed to be mediated by the cAMP and phosphatidylinositol second messenger systems.

Development of heart rate in the precocial king quail Coturnix chinensis

Our aim was to examine changes in heart rate (fh) during the embryonic and posthatching periods of the smallest precocial avian species, Coturnix chinensis. In experiment I, repeated measurements of mean fh were made for individual quail by ballistocardiogram (BCG) during incubation, and by both piezo-electric film and electrocardiogram (ECG) during the posthatching period (resting and thermoneutral conditions). Mean fh of all embryos increased during the second half of incubation and the first week posthatching, but a few embryos experienced a very brief period of decreased fh prior to internal pipping. After the first week, fh of posthatching quail was maintained at high levels (550-650 beats min-1), then decreased with age and increase in body mass. The maximal fh of quail chicks represents a greater posthatching increase in fh than is found in larger precocial chickens, this difference being attributable to the higher demands of thermoregulation at small body masses in the quail. In experiment II, the mean fh of quail embryos (day 2-16) was recorded by ECG, and embryonic stage, yolk-free embryo mass (wet and dry) and water content were measured. Mean fh was linearly related to embryo mass throughout incubation, except on the day prior to internal pipping, when the fh of a few embryos declined below this linear relationship. Measurements of instantaneous fh of late incubation embryos, young and adult quail all showed spontaneous fluctuations in fh. Two main frequency components of fh fluctuations were identified for the first time in an avian species. Low-frequency (mean 0.09 Hz, 12.6 s) and high-frequency (1.4 Hz, 0.9 s) oscillations in both young chicks and adult quail were detected and are considered to reflect baroreflex mediation of fh and respiratory sinus arrhythmia, respectively.

Development of thermoregulation and posthatching growth in the altricial cockatiel Nymphicus hollandicus

The development of thermoregulation and growth during the nestling period of cockatiel Nymphicus hollandicus were examined in this study. It was hypothesised that, in comparison to other altricial species of similar body mass, cockatiel chicks develop endothermy earlier and consequently have less energy available for growth, resulting in reduced growth rates. While poorly insulated and blind at hatching, cockatiel developed endothermic responses in their first week, and were individually effectively homeothermic (with 75% of adult ability to maintain body temperature during exposure to 20 degrees-25 degrees C), by maintaining high metabolic rates (at all ambient temperatures tested) above the predicted resting rates of an adult of similar body mass before parental brooding ceased (12-13 d). Mass-independent metabolic rates were equivalent to those of fledglings at only 20% of the nestling period (37 d), well before adequate insulation was obtained. The Gompertz growth constants of cockatiel were significantly lower than those of other altricial land birds, which supports the hypothesis of this study.

Ballistocardiogram of avian eggs determined by an electromagnetic induction coil

As an avian embryo grows within an eggshell, the whole egg is moved by embryonic activity and also by the embryonic heartbeat. A technical interest in detecting minute biological movements has prompted the development of techniques and systems to measure the cardiogenic ballistic movement of the egg or ballistocardiogram (BCG). In this context, there is interest in using an electromagnetic induction coil (solenoid) as another simple sensor to measure the BCG and examining its possibility for BCG measurement. A small permanent magnet is attached tightly to the surface of an incubated egg, and then the egg with the magnet is placed in a solenoid. Preliminary model analysis is made to design a setup of the egg, magnet and solenoid coupling system. Then, simultaneous measurement with a laser displacement measuring system, developed previously, is made for chicken eggs, indicating that the solenoid detects the minute cardiogenic ballistic movements and that the BCG determined is a measure of the velocity of egg movements.

Non-invasive determination of instantaneous heart rate in developing avian embryos by means of acoustocardiogram

Previous noninvasive studies of the mean heart rate of embryonic birds have prompted an investigation into the instantaneous heart rate (IHR), which may be informative in developmental studies of cardiac rhythm. Using the acoustocardiogram (ACG), a noninvasive, long-term measuring system for embryonic IHR is developed, and the IHR in chickens during the last half of embryonic development is determined. The system, which uses a micro-computer, samples the ACG at a frequency of 50 Hz, restores the ACG wave by sinc function and calculates the IHR with an error in accuracy of less than 1 beat min-1. It was found that characteristic, transient bradycardia begins to appear late in the second week of incubation, and, with the additional development of transient tachycardia, the embryonic cardiac rhythm becomes more arrhythmic towards hatching. Simultaneous measurements of IHR with somatic movements showed no relationship between arrhythmia and embryonic activities. This system is useful, providing new evidence on long-term IHR developmental patterns.

Developmental patterns of O2 consumption, heart rate and O2 pulse in unturned eggs

The effects of failure to turn eggs on the developmental patterns of oxygen consumption (MO2), heart rate (fH) and O2 pulse during the second half of incubation of individual chicken eggs were examined. The MO2 of unturned eggs increased at a significantly lower rate than the control toward the end of prenatal incubation, and the plateau MO2 between day 17 and 19 was significantly lower than the control. Lack of turning also resulted in significant changes in the developmental patterns of fH and O2 pulse. It is suggested that the effects of lack of egg-turning on the developmental patterns of MO2 may be attributable to lower embryonic growth rate in addition to impairment of gas exchange through the chorioallantoic gas exchanger.

Effects of pre-incubation egg storage on embryonic functions and growth

The effect of pre-incubation storage on physiological functions of chick embryos during the last half of incubation and the relationship to embryonic growth were studied. In the first experiment, eggs were stored for 20 or 30 days, respectively, and the developmental patterns of oxygen consumption (MO2), heart rate (fH) and O2 pulse of individual embryos were examined. The MO2 of stored eggs increased at significantly lower rate than the control between day 12 and 17 of incubation, and the stored eggs had a significantly lower plateau MO2 between day 17 and 19. The decrease in MO2 of some stored eggs was correlated with late incubation mortality. Pre-incubation storage also resulted in significant changes in the developmental patterns of fH and O2 pulse. In the second experiment, the eggs were stored for 10 and 20 days, respectively, to also examine the effect of short-term storage on the development of MO2 in relation to embryo growth. Pre-incubation storage for 10 days had no significant effect, but 20 days storage shifted developmental patterns of MO2, wet mass, dry mass and embryo water fraction to the right of the control. Furthermore, MO2 was significantly lower than expected on the basis of embryo mass after day 17 of incubation. Prolonged pre-incubation storage caused not only a rightward shift in MO2 pattern due to retarded growth, but also severe depression of MO2 during the last stages of prenatal development.

A rodent model for hemoglobin switching utilizing high performance liquid chromatography

It has long been recognized that a treatment for beta hemoglobin chain anomalies could result if a way to reverse the Hb F to Hb A switch in humans were found. Studies of hemoglobin switching have been hampered by the fact that small animals normally used in the laboratory do not have a true Hb F. However, several small animal models which take advantage of a switch in minor beta chain proportions in certain strains of inbred mice and rats have been proposed and used. The use of these models has suffered from what, until now, could be considered technically demanding, time-consuming methodologies. In this study we report an effective, rapid and technically streamlined model of hemoglobin switching utilizing Fisher 344 rats and high performance liquid chromatography with a weakly cationic column.

Oxygen consumption rates of adults and chicks during brooding in king quail (Coturnix chinensis)

Oxygen consumption rates were measured in chicks (0-17 days of age), and in non-brooding and brooding adults. Brooded chicks maintained a constant oxygen consumption rate at a chamber ambient temperature of 10-35 degrees C (0-5 days of age: 2.95 ml O2.g-1.h-1 and 6-17 days of age: 5.80 ml O2.g-1.h-1) while unbrooded chicks increased oxygen consumption rate at ambient temperature below 30 degrees C to double the brooded oxygen consumption rate at 25 and 15 degrees C for chicks < 5 days of age and > 5 days of age, respectively. The mass-specific oxygen consumption rate of breeding male and females (non-brooding) were significantly elevated within the thermoneutral zone thermal neutral zone (28-35 degrees C) in comparison to non-breeding adults. Below the thermal neutral zone, oxygen consumption rate was not significantly different. The elevation in oxygen consumption rate of breeding quail was not correlated with the presence of broodpatches, which developed only in females, but is a seasonal adjustment in metabolism. Male and females that actively brooded one to five chicks had significantly higher oxygen consumption rate than nonbrooding quil at ambient temperature below 30 degrees C. Brooding oxygen consumption rate was constant during day and night, indicating a temporary suppression of the circadian rhythm of metabolism. Brooding oxygen consumption rate increased significantly with brood number, but neither adult body mass nor adult sex were significant factors in the relationship between brooding oxygen consumption rate and ambient temperature. The proportion of daylight hours that chicks were brooded by parents was negatively correlated with ambient temperature. After chicks were 5 days old brooding time was reduced but brooding oxygen consumption rate was unchanged. Heat from the brooding parent appeared to originate mainly from the apteria under the wings and legs rather than the broodpatch. The parental heat contribution to chick temperature regulation below the chicks' thermal neutral zone is achieved by increasing parental thermal conductance by a feedback control similar to that suggested for the control of egg temperature via the broodpatch. It is concluded that the brooding period is an energetic burden to parent quail, and the magnitude of the cost increases directly with brood number and inversely with ambient temperature during this period.(ABSTRACT TRUNCATED AT 400 WORDS)

Segmental intestinal muscular thinning: a possible cause of intestinal obstruction in the newborn

Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.

Rates of accumulation of dieldrin by a freshwater filter feeder: Sphaerium corneum

The rate of dieldrin accumulation by Sphaerium corneum was determined in the field and under controlled conditions in the laboratory. The methods gave comparable results and it was established that Sphaerium attained an equilibrium concentration of dieldrin in its tissues in a short time period and exhibited a bioaccumulation factor of 1000. The rate of dieldrin accumulation by direct uptake from dieldrin in solution was compared to the rate obtained for indirect uptake from dieldrin adsorbed onto particulate material. The primary route of dieldrin uptake into Sphaerium was shown to be by direct partitioning of residues into lipoidal tissues from water. The effect of temperature on the rate of accumulation was also studied. The rate of accumulation increased with temperature in the range 5 degrees C to 20 degrees C. The frequency of gill cilia beat in relation to accumulation rate was studied in this temperature range and a correlation is shown.

The mode of action of anabolic agents: the effect of testosterone on muscle protein metabolism in the female rat

Testosterone (1 mg/kg body-weight per d) given subcutaneously to female rats increased their growth rate and food conversion efficiency but not their food intake compared with that of the placebo-oil controls. A higher dose of testosterone (10 mg/kg body-weight per d) failed to increase the daily weight gain. The increased growth rate of the testosterone-treated rats appeared to occur in the whole body and not specifically in muscle. There were no significant changes in body composition. The fractional synthetic rate of gastrocnemius muscle protein was higher in the hormone-treated rats than in controls. This contrasts with previous results for the anabolic agent trenbolone acetate and reflects differences in the mode of action of these two different steroids, both with androgenic properties.

The use of a bromide ion selective electrode for the measurement of counter-ion activity in cationic surfactant solutions

A bromide ion selective electrode has been used in conjunction with a saturated calomel reference electrode to measure bromide ion activity in solutions of n-decyl, n-dodecyl, n-tetradecyl and n-hexadecyl 1-trimethylammonium bromides at 30°; the critical micelle concentrations of the surfactants were measured by electrical conductance. Calibration of the electrode pair in potassium bromide solutions produced a linear response over the range 0·5 to 5·0p Bra− with a slope of 59·1 mV for a 10-fold change in activity. Results for the surfactants were treated to give values for the degree of micellar dissociation; literature values for this quantity reveal wide variation depending on the technique used.

Potentiometric determination of sodium using a sodium ion responsive glass electrode

A study to assess the feasibility of using a sodium ion responsive glass electrode in conjunction with a saturated calomel reference electrode to measure the sodium ion concentration of a wide range of electrolyte solutions used in clinical medicine has shown that the method is capable of giving results which are within acceptable limits. Direct measurement of solutions containing sodium chloride is possible by reference to a calibration based on the potential produced by the electrode pair as a function of pNa+ defined as -log10 sodium ion concentration. For the measurement of the sodium content of solutions of sodium salts of weak acids and mixed solutions of electrolytes and dextrose it is necessary to use a calibration carried out in a buffer system (0·5M triethanolamine + hydrochloric acid to pH 7) and to dilute the preparations with buffer before measurement. It is also necessary to buffer dextrose and sodium chloride injection before measurement due to the effect of decomposition of dextrose during sterilization causing a shift in pH which must be corrected before making a determination. The advantages of the potentiometric method over conventional flame photometric and titrimetric methods are discussed and a brief review of the literature given, to indicate the applications of specific ion electrodes.

Crystal growth studies involving phase transitions in aqueous drug suspensions

The growth of oxyclozanide crystals in quiescent suspensions has been monitored using the Coulter Counter. Increase in particle size is the result of an isothermal, solvent-mediated phase transition between two unsolvated polymorphs, one having a lower solubility than the other. Effects due to Ostwald ripening and temperature cycling are absent. Theophylline, which shows crystal growth in suspension by hydration, has been studied by photomicrography. Preliminary results indicate that the initial rate of growth in such systems may be qualitatively described in terms of steady-state diffusion theory.