Biomedical subjects
Publications and source records attributed to P Thaxton.
Agranulocytes proliferated in spleens of molted hens and both leucocytic and erythrocytic cells exhibited decreased numbers of pyknotic nuclei. These changes were confined to the period when the reproductive tract regressed. It was concluded that there is a relationship between the physiological status during an induced molt and the cellular population of the spleen.
Four-week-old Japanese quail were placed in either stable (isolate) or unstable (resident-visitor) groupings in this study. The visitor quail were transferred daily to cages containing unfamiliar residents, and the isolate quail were handled daily. The immune responsiveness to sheep red blood cells (SRBC), as indicated by production of hemagglutinins of the visitors and residents, was significantly less than that of the isolates, and the visitors were found to have less antibody than the residents. In subsequent experiments adrenocorticotropic hormone (ACTH) was used to compare its effect on immune responsiveness to that caused by grouping. The ACTH caused a suppression in humoral immune response, but only 8 IU ACTH/100 g body weight consistently suppressed antibody levels, indicating that the quail immune system is moderately resistant to this hormone. At the end of the experimental periods the bursa of Fabricius, spleen, and adrenal glands were removed. The relative weights of the organs suggested that grouping and ACTH did not induce the classical symptoms of physiological stress. However, stress was not eliminated as a possible cause of the immunosuppressive effects of grouping and ACTH found in this study, because there was significant body weight loss in unstable groupings and in ACTH-treated birds.
Packed cell volume and circulating leucocyte numbers in force-molted, Single Comb White Leghorn (SCWL) hens were examined. Two groups of SCWL hens, reared under commercial conditions, were subjected to force molting (FM) at 70 (Trial 2) and 72 weeks of age (Trial 1). The force molting procedure consisted of a reduced photoperiod (6 hr), feed removal for 12 days (Trials 1 and 2), and water withdrawal for 1 day (Trial 1 only). Cessation of egg production was achieved in 6 days. Control (CON) hens were maintained in each trial with no change in daylength, and feed and water were available ad libitum. The FM hens exhibited a significant increase in packed cell volume (PCV) from the time of feed removal until immediately prior to resumption of egg production. This effect was not associated with water deprivation. The FM hens exhibited numerically increased numbers of total leucocytes (TWBC) and monocytes throughout the nonlaying period. However, the increase was significant on Day 14 of both trials for TWBC and on Days 21 and 35 (Trial 1) and Days 14 and 48 (Trial 2) for monocytes. A significant eosinophilia was observed on Days 7 and 14 of both trials. Changes associated with lymphocytes, heterophils, and basophils were inconsistent. Lymphocytes were increased significantly in the FM hens of Trial 2 from Day 21 to Day 48, but no significant difference occurred in Trial 1. A heterophilia was exhibited by the FM hens of Trial 1 on Days 7 and 14, but not in Trial 2. Conversely, a significant basophilia was observed on Days 7 and 14 in Trial 2, but not in Trial 1. These data suggested that an increased PCV, eosinophilia, and possibly increased TWBC and monocyte numbers were associated with a forced molt in caged SCWL hens.
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Juvenile male chickens were exposed continuously to 300 micrograms/ml of mercury (Hg) in the form of mercuric chloride (HgCl2), via the drinking water, from hatching through six weeks of age. Serum osmolality and plasma potassium were increased significantly as a result of the Hg treatment. Plasma sodium was increased numerically in two of the three trials. Of the serum proteins, only albumin and the transferrins exhibited a consistent significant increase. It is concluded that alterations in serum ions and proteins account for the significant increase in plasma osmolality. The increase in transferrins may represent a mechanism to bind and detoxify Hg.
The effects of forced molting on body temperature and selected blood constituents were studied. Caged layers, reared under commercial conditions, were force molted successively at 72 and 104 weeks of age. This was accomplished by removing feed for up to 12 days and water for up to 3 days while simultaneously reducing the day length to 10 hr or less. This procedure resulted in a cessation of egg production within one week of the initiation of feed removal. There was a significant increase in body temperature during feather loss and renewal. Packed cell volume and hemoglobin increased significantly immediately upon removal of feed and water and remained elevated above control levels for the duration of the pause in egg production, while plasma total calcium, and inorganic phosphate decreased significantly during the corresponding period. Plasma total protein and plasma glucose did not exhibit consistent trends. Body temperature and the levels of the measured plasma consituents returned to normal levels upon the resumption of egg production.
The effects of forced molting on body weight and the absolute and relate weights of the liver, ovary, oviduct, right adrenal, and spleen were studied. White Leghorn hens which were reared and maintained under commercial conditions were force molted by reducing daylength as well as by withdrawing feed and water. This procedure induced a pause in egg production within one week of the initiation of feed removal. Four trials were conducted. In Trial 1 the hens were sampled at weekly intervals for 56 days beginning at the time feed was removed. In Trials 2, 3, and 4 the hens were sampled either daily or on alternate days for up to 22 days beginning at the time of feed removal. The absolute and relative weights of the liver, ovary, and oviduct were decreased significantly. Body weight decreased consistently. No consistent trend over the four trials was found in the absolute or relative weights of the right adrenal or the spleen.
The effects of forced molting on plasma levels of thyroxine (T4), triiodothyronine (T3), and adrenal cholesterol and total adrenal steroid content were studied. Commercially available strains of Single Comb White Leghorn (SCWL) hens, reared and maintained under commercial conditions, were used in the three trials. The hens were moved to environmentally modified facilities prior to the forced molt which was accomplished by reducing daylength and by withdrawing feed and water. Egg production ceased within one week of initiation of this procedure. The hens were sampled either daily or an alternate days for up to 22 days beginning at the time of feed removal. Plasma T4 initially decreased upon removal of feed, but increased above control levels by the sixth day of feed withdrawal. Plasma T3 levels remained relatively constant throughout the feed withdrawal period. Resumption of feeding with a fortified ground corn ration resulted in a decrease in T4 and concomitant increase in T3. Changes in adrenal cholesterol and total adrenal steroids were not consistent. However, there was a trend toward increased total adrenal steroids during feed withdrawal, and an increase in adrenal cholesterol upon the resumption of feeding.
Four trials were conducted to determine if toxic levels of mercury affect kidney development, morphology, and renal function. Mercury, administered via the drinking water as mercuric chloride caused a reduction in gross kidney weight, an increase in relative kidney weight and a slight but significant increase in the percentage water retained by left kidney of 6-week-old cockerels. Mercury had no effect on renal function of 6-week-old birds as indicated by the clearance of phenol red from circulation. Histological discontinuity of the kidney was extensive and evidenced by foamy cell degeneration and nuclear pyknosis. Although mercury caused gross alterations in the morphology of the kidney, normal excretory function was maintained.
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Juvenile chickens were either chronically exposed to 300 microgram/ml of Hg in the drinking water (chronic dosage--CD) or acutely exposed to either 3 mg of Hg/kg body wt (acute low dosage--ALD) or 12 mg of Hg/kg body wt (acute high dosage--AHD) administered intramuscularly for five consecutive days. Only the CD and AHD treatments retarded normal growth. Relative heart weights were increased by the CD treatment, decreased by the AHD treatment, and remained unchanged during the ALD treatment. Relative aorta weights were increased by the CD treatment but decreased by the AHD treatment. ECG analyses revealed a consistent decrease in the amplitude of the R-S and T waves with the greatest effects present in the acute (ALD and AHD) treatments. Histological examination revealed that Hg caused myocardial histopathological changes characterized as a myocarditis with polymorphonuclear and lymphocytic infiltration and fatty degeneration. It is concluded tha Hg causes cardiovascular disturbances in chickens even when administered at levels which do not inhibit normal growth.
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Previous reports indicate that Japanese quail are hyporesponsive to such conventionally used antigens as sheep red blood cells and bovine serum albumin. In this study the immune responsiveness of Japanese quail to several erythrocyte antigens was investigated. The quail produced higher antibody titers when immunized with chukar red blood cells than when immunized with sheep, turkey, or pheasant red blood cells. It is concluded that Japanese quail are capable of producing HA titers comparable in magnitude to those demonstrated by other laboratory animals, when the quail are immunized with an appropriate antigen. Chukar red blood cells are such an antigen.
The immunosuppressive effects of passive transfers of specific immunoglobulin preparations obtained from immune or hyperimmune sera were evaluated in chickens which were challenged with sheep red blood cells. The data indicate that IgY, fractionated from immune sera, and IgY and IgM, fractionated from hyperimmune sera, when passively administered at the doses employed in this study resulted in antibody-mediated suppression.
Exogenous ACTH, when administered intramuscularly in four equal doses of 2 I.U./100 gm. of body weight at 24, 23, 22, and 21 hours prior to challenge with BSA, reduced the severity of anaphylaxis in BSA sensitized juvenile chickens. Additionally, a single heat exposure (45 degrees C.) of 30 minutes at 24 hours prior to challenge consistently reduced the severity of anaphylaxis. Single heating exposures at 24 hours prior to sensitization or at 48 hours prior to challenge did not influence the anaphylactic response. In one of two experiments single heat exposures at one hour prior to challenge reduced the severity of anaphylaxis. The levels of anti-BSA antibody which existed immediately prior to challenge were not affected by the heat treatments. These data demonstrate clearly that exogenous ACTH and a single, non-lethal heating episode, when applied 24 hours prior to the induction of anaphylaxis, reduced the severity of the symptoms associated with this particular hypersensitive reaction in the domestic chicken.
Exposure of quail eggs 4 hr per day during the first 5 incubation days at 2450 MHz and in an exposure field of 30 mW/cm-2 and at an absorbed power of 14 mW/g does not cause any great change in body weight, observed gross malformations, rbc, wbc, hematocrit, hemoglobin, or differential wbc percentages. If small differences exist in these parameters due to microwave exposure, they are obscured by the large variability between individual quail. This variability is believed to partially result from changing blood values in the developing young quail, and the 2-day spread in ages at the time of sacrifice could account for some of the variability. The overall hatch percentages for the exposed and control eggs were approximately equal. A slight significant decrease (11%) in hemoglobin was noted in the birds irradiated on Day 2. Additional verification, however, is needed, because the observed change is less than the normal range of values observed in young quail. These data do suggest, however, that exposure of developing Japanese quail embryo to microwave radiation of the frequency and power density level used in this study does not preclude normal systemic development, hematologic differentiation, or the general hardiness of the hatched quail.
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Juvenile chickens that had previously received mercuric chloride intramuscularly were subjected to an acute exposure of high ambient temperature in the presence or absence of a 140 mpm air velocity. This level of mercury did not retard growth of affect the resting body temperature. However, following heating the birds experienced a greater hyperthermia than similarly heated controls and consequently thermal death occurred earlier. When a high air velocity was maintained during heating the hyperthermic condition was further amplified, as was the event of thermal death. It is concluded that a synergistic relationship exists between mercury, when administered at a nontoxic level, and the climatic factors of temperature and air velocity.