Biomedical subjects

M M Mashaly

Publications and source records attributed to M M Mashaly.

At least 37 records · Page 2Linked to original sources

PubMed1994

Bursectomy and in vitro response of adrenal gland to adrenocorticotropic hormone and testis to human chorionic gonadotropin in immature male chickens.

This investigation was carried out to determine the effects of bursectomy on in vitro response of adrenal glands to adrenocorticotropic hormone (ACTH) and testes to human chorionic gonadotropin (HCG) in immature male chickens. One-day-old Single Comb White Leghorn male chicks were surgically bursectomized (BSX). Sham-operated (sham) chicks were used as controls. At 5 wk of age, adrenal cortical cells (ACC) from BSX and sham birds were incubated in vitro with various concentrations (0, 10(-7), 10(-6), and 10(-5) M) of ACTH for 2 h, and then corticosterone was measured in all supernatants. At 15 wk of age, Leydig cells from testes of both groups were incubated in vitro with HCG (3,000 IU/mL) for 3 h, and then testosterone was measured in all supernatants. Corticosterone concentrations in response to both 10(-6) and 10(-5) ACTH were significantly lower for BSX than for sham ACC. Leydig cells from sham birds produced significantly more testosterone than those of BSX birds whether or not the cells were stimulated with HCG. Furthermore, Leydig cells from sham birds, but not from BSX birds, produced significantly more testosterone when stimulated with HCG than when saline was added. These results indicated that the bursa of Fabricius or its products might have a stimulatory effect on the response of ACC and Leydig cells to ACTH and HCG, respectively.

Adrenal Glands↗

PubMed1994

The effects of adrenocorticotropic hormone and heat stress on the distribution of lymphocyte populations in immature male chickens.

This study investigated the effects of heat stress and adrenocorticotropic hormone (ACTH) on the distribution of lymphocyte populations. Two experiments were conducted; each used 12-wk-old Cornell K-strain male chickens. In Experiment 1, birds were exposed to a temperature of 35 C, 6 h/d for 5 d and control birds were maintained at 24 C. In Experiment 2, birds received daily i.m. injections of 50 IU/kg body weight of ACTH for 5 d and control birds received .9% saline. On Day 6, blood and spleens were collected and lymphocytes were isolated. Indirect immunofluorescent labeling of lymphocytes were performed to detect B lymphocytes, CD4+ cells, and CD8+ cells. Neither ACTH injection nor heat stress affected percentages of B lymphocytes in the blood or the spleen. The CD4+ cells decreased significantly in the blood of ACTH-injected and heat-stressed birds and significantly increased in the spleens of heat-stressed birds. The CD4+ cells in the spleens of ACTH-injected birds did not differ from controls. The CD8+ cells significantly declined in the blood following both ACTH injection and heat stress and significantly increased in the spleen of the ACTH-injected birds but did not differ from controls in the heat-stressed birds. These results indicate that stress factors lead to redistribution of different lymphocyte populations.

Adrenocorticotropic Hormone↗

PubMed1993

The endocrine function of the immune cells in the initiation of humoral immunity.

The endocrine functions of different hormones are well documented. Recently, however, evidence of the immune function of several hormones has been accumulated. These findings raised the possibility that immune cells might secrete hormones and in turn self-regulate different immune functions. Indeed, immune cells have been found to secrete different peptide and protein hormones. Adrenocorticotropin hormone (ACTH) is the most studied and was found to be secreted by lymphocytes. In the present authors' laboratory, it was found that not only do lymphocytes secrete ACTH but also that circulating concentrations of corticosterone increased following antigen challenge. It was also observed that at the time of the increased corticosterone, there was a redistribution of different lymphocyte subpopulations from the blood to spleen, the site of antigen presentation and antibody production. It was concluded that the endocrine function of lymphocytes might be important in the initiation of antibody production in chickens.

Adrenocorticotropic Hormone↗

PubMed1992

Augmentation of natural cell-mediated cytotoxic activity by supernatant from in vitro mitogen-stimulated, in vivo hormone-treated lymphocytes in immature male (K strain) chickens.

Newly hatched White Leghorn male chicks were used in this study. Triiodothyronine (T3; 0.1 or 1 ppm) and Thyrotropin Releasing Hormone (TRH; 1 or 5 ppm) were added to the feed for an 8-week period starting at hatch. A fifth group received the unsupplemented diet and served as controls. Peripheral blood lymphocytes from each treatment group were cultured in vitro with or without different mitogens (PHA, Con-A, or LPS), and the culture supernatants were tested for the presence of lymphokines (LK). The natural cell-mediated cytotoxicity (NCMC) assay was carried out with or without supernatant using the standard chromium (Cr51) release assay. Control untreated chicks were used as donors for effector cells and the P815 mouse mastocytoma was used as a target. Supernatant from in vivo 1 ppm T3- or 5 ppm TRH-treated lymphocytes significantly suppressed NCMC (or cells mediating NCMC, e.g., NK cells). However, supernatant from 1 ppm T3-treated, PHA-stimulated lymphocytes significantly enhanced NK cells cytotoxicity, while supernatant from 5 ppm TRH-treated lymphocytes with PHA stimulation tended to suppress cytotoxicity. These results provide evidence supporting a regulatory role of the hypothalamo-pituitary thyroid axis on lymphokine (LK) production. The results also suggest that these hormones act on different subpopulation of lymphocytes, and therefore, the mediators released by them.

Animals↗

PubMed1992

Broiler production under varying population densities.

The influence of population density on the growth performance and stress level of Hubbard x Hubbard chicks of equally mixed sex was studied. Six hundred and sixteen birds were housed under .05, .07, .09, or .11 m2 per bird (four replicates per density) from 0 to 7 wk. There were no treatment effects on feed conversion at 6 or 7 wk. Birds housed at .07, .09, and .11 m2 per bird had similar 7-wk BW and carcass weights, all significantly higher than birds housed at .05 m2 per bird. Under .05 m2 per bird, a higher percentage of breast blisters and ammonia burns (30%) was observed than at other densities. The 7-wk heterophil to lymphocyte ratios of birds raised at .09 and .11 m2 per bird (.42 and .45) were significantly higher than those at .05 and .07 m2 per bird (.28 and .30). Lowered BW and decreased carcass quality of birds raised at .05 m2 per bird suggested that these birds were stressed. However, decision analysis of economic potential indicated that the optimum profit potential per square meter was .05 m2 per bird for Maximax and Equally Likely decisions and .07 m2 per bird for the Maximin decision.

Animal Husbandry↗

PubMed1991

Characterization by scanning and transmission electron microscopy of avian peripheral blood mononuclear cells exhibiting natural killer-like (NK) activity.

Peripheral blood mononuclear cells (MN) were isolated from 10-week-old Single Comb White Leghorn female chickens (Cornell K strain) and incubated with either LSCC-RP9 or P815 tumor cells at a ratio of 200:1. Samples were filtered through a 2 micron nucleopore filter at 15 min, 30 min, 1 hr, 2 h, 3 h, and 4 h following incubation to isolate conjugates for scanning electron microscopy (SEM). For transmission electron microscopy (TEM), MN were incubated with LSCC-RP9 tumor cells at a ratio of 200:1 for 1 h. Conjugates in the suspension were fixed, stained, and embedded for thin sectioning. Samples were viewed to determine morphological characteristics of cells having NK-like ability and tumor cell destruction process. The MN possessing NK-like activity appear to be small lymphocytes (5-6 microns in diameter) with a small cytoplasm to nuclear ratio and many surface projections. In addition, it was shown that conjugate formation occurred in both tumor cell lines and the lymphocyte surface projections appear to play a role in the destruction process. Tumor cell destruction did occur with both cell lines, however, the LSCC-RP9 tumors cells were destroyed more rapidly.

Animals↗

PubMed1991

Chicken growth hormone, triiodothyronine and thyrotropin releasing hormone modulation of the levels of chicken natural cell-mediated cytotoxicity.

Newly hatched White Leghorn male chicks received dietary supplements of either Triiodothyronine (T3) or Thyrotropin Releasing Hormone (TRH) until 8 weeks of age. Chicken growth hormone (cGH) (10 micrograms/kg BW) was injected into different chicks twice daily for 1 week starting at 7 weeks of age. Separate groups received both T3 and cGH. Natural cell-mediated cytotoxic (NCMC) activity against different target cells was tested. It was found that cytotoxic activity in cells involved in NCMC against P815 mouse mastocytoma was stimulated by cGH alone or in combination with T3 (1 ppm). These findings indicate that cGH and T3 stimulate NCMC activity; and that the cells responsible for this activity may be Natural Killer (NK) cells.

Animals↗

PubMed1991

In vivo effects of TRH, T3 and cGH on antibody production and T- and B-lymphocytes proliferation in immature male chickens.

Newly hatched White Leghorn male chicks were used in this study. Different doses of T3 (0.1 or 1 ppm) or TRH (1 or 5 ppm) were administered in the feed for an 8-week period. Chicken growth hormone (cGH) (10 micrograms/kg BW) was injected (i.v.) into a different group of chicks twice daily for 1 week starting at 7 weeks of age. A different group received both T3 (0.1 and 1 ppm) and cGH. Serum concentrations of T4, T3 and GH, antibody production against sheep red blood cells (SRBC) and Brucella Abortus (BA), and in vitro proliferative response of both T- and B-lymphocytes to mitogenic stimulation were measured. Supplementation of T3 (1 ppm) significantly lowered T4 and increased T3 concentrations. No effect of any hormone treatment on antibody production was observed. T3 supplementation and cGH injection alone or with T3 (0.1 ppm) significantly increased blastogenic response of lymphocytes to either Con-A or LPS mitogenic stimulation. It was concluded that T3 and GH are involved in lymphocyte activity of chickens.

Animals↗

PubMed1991

Ovine corticotropin-releasing factor increases endocrine and immunologic activity of avian leukocytes in vitro.

Treatment of splenic leukocytes from Cornell K strain male chickens (homozygous at the B15 locus of the major histocompatibility complex) with ovine corticotropin-releasing factor (oCRF), before their co-incubation with naive chicken adrenal cells, resulted in an increase in corticosterone production. Supernatants from the oCRF-treated splenic leukocytes caused a time-dependent increase in corticosterone production when incubated with chicken adrenal cells. Adding oCRF directly to chicken adrenal cells did not increase corticosterone production. Pretreatment of peripheral leukocytes with oCRF increased their activity in a concanavalin A mitogen assay. Thus, chicken leukocytes stimulated with corticotropin releasing factor appear to increase the production of an "adrenocorticotropin-like" substance (adrenocorticotropin-like because it increases corticosterone production by adrenal cells), and increased their cell-mediated immune activity.

Adrenal Glands↗

PubMed1991

Effect of exogenous corticosterone on chicken embryonic development.

Embryonic corticosterone (CS) levels were altered by dipping 3-day-old fertile Leghorn eggs in 0, .01, .05, and 1% CS dissolved in absolute ethanol. Mortality was determined by candling from Day 4 through hatch. Body weights and serum CS were measured daily from Day 14 until hatch. Embryos of eggs dipped in 1% CS in ethanol solution had reduced circulating CS. Embryo weights were reduced and mortality increased as concentration of hormone increased. A CS peak was observed just before hatch for control, .01 and .05% groups, but not for the .1% group. All embryos in the .1% treatment group died before hatch. The importance of embryonic CS for normal development and hatching was indicated.

Animals↗

PubMed1990

The effect of different feed restriction treatments during rearing on the luteinizing hormone concentrations, body weight, and fertility of broiler-breeder cockerels.

Broiler breeder cockerels were reared on four feed-restriction programs from 3 to 23 wk of age (Experiment 1). Excessive BW restriction (85% of the controls) throughout rearing significantly decreased fertility at 28 wk of age, but not at 31 or 35 wk of age. There were no carryover treatment effects on BW at 30, 35, or 45 wk of age. Significant peaks occurred in the concentration of the serum luteinizing hormone (Experiment 1, 7.05 ng per mL; Experiment 2, 7.36 ng per mL) at 33 to 35 wk of age.

Animals↗

PubMed1990

Effect of thyrotropin-releasing hormone, triiodothyronine, and chicken growth hormone on plasma concentrations of thyroxine, triiodothyronine, growth hormone, and growth of lymphoid organs and leukocyte populations in immature male chickens.

One-day-old White Leghorn male chicks were fed different levels of Thyrotropin Releasing Hormone (TRH) (1 and 5 ppm) or Triiodothyronine (T3) (.1 and 1 ppm) for an 8-wk period. In a second experiment, chicken growth hormone (cGH) (10 micrograms/kg of BW) was injected (iv) into different birds daily for 7 days starting at 7 wk of age. Different groups of birds received both T3 (.1 and 1 ppm) and cGH. Serum concentrations of thyroxine (T4), T3, and growth hormone (GH), lymphoid organ weights, total circulating white blood cells (WBC), and differential counts were measured following hormone treatments. It was found that T3, cGH, or a combination of both significantly lowered serum T4 concentrations. Triiodothyronine supplementation at 1 ppm, alone or with cGH significantly increased serum T3 concentrations. Chicken GH with T3 (.1 ppm) significantly increased serum GH concentrations. Thyrotropin releasing hormone supplementation did not affect serum concentrations of either T4, T3, or cGH. Relative bursa weights were greater in chicks that received T3 (1 ppm) or TRH (1 or 5 ppm) but not cGH. Relative spleen weights were enhanced in response to cGH alone or with T3 (1 ppm) but not TRH. Total WBC count was significantly increased in response to T3 (1 ppm). Supplementation of T3 (.1 or 1 ppm), TRH (1 ppm), and the combination of cGH and T3 (1 ppm) significantly increased the percentage of lymphocyte cell population. These results demonstrate the impact of feeding hormones on T3, T4, and cGH concentrations in the serum and suggest the involvement of the above hormones in the growth of lymphoid organs as well as the production of lymphocytes.

Animals↗

PubMed1989

Effect of thyroidectomy of immature male chickens on circulating thyroid hormones and on response to thyroid-stimulating hormone and chronic cold exposure.

Previous studies in the author's laboratory established that thyroidectomized (Tx) immature male chickens had significant levels of circulating thyroid hormones, and it was proposed that extrathyroidal tissue might be present. Three experiments were conducted to further investigate this possibility. In all experiments, thyroid glands were removed surgically at 3 wk of age. In the first experiment, birds were kept until 20 wk of age. It was found that only triidothyronine levels were reduced significantly in the Tx birds. In the second experiment, Tx as well as sham-operated control groups received a single iv injection of bovine thyroid-stimulating hormone (TSH) to determine if extrathyroidal tissue in Tx birds would respond to exogenous TSH. It was found that circulating thyroxine (T4) concentrations in sham-operated control birds, but not Tx birds, were increased following TSH injection. In the third experiment, Tx and sham-operated birds were exposed chronically to cold (7 C), and only circulating T4 was found to be elevated in both groups. It was concluded that extrathyroidal tissue in Tx birds does not respond to TSH.

Aging↗

PubMed1988

Changes in the profiles of circulating white blood cells, corticosterone, T3 and T4 during the initiation of humoral immunity in immature male chickens.

Eight-week-old male White Leghorn chickens were injected intravenously with either 0.1 ml of Brucella abortus (BA) or saline. Blood samples were collected before injection, 1 hr, 3 hr, 6 hr, 12 hr, 24 hr, and then daily for the following 6 days after the injection. Total white blood cells (WBC), differential counts and corticosterone (CS), T3 and T4 levels were measured in all blood samples. These data represented the results obtained from the primary response. To obtain data for the secondary response, the same birds were injected 4 weeks following the first challenge and the same procedure was followed. During primary and secondary responses, circulating lymphocytes and monocytes decreased significantly 3 hr following BA injection and then increased steadily and reached a peak approximately 5 days post-BA injection, however, circulating heterophils increased significantly 6-12 hr and returned to normal levels 2 days post-BA injection. Serum corticosterone increased significantly 3 hr following BA injection. Serum T3 decreased significantly 3 to 12 hr then increased significantly 2 days following BA injection. There were no significant changes in any of the measurements following saline injection. Correlations between circulating hormones and white blood cells were calculated and are reported. These results indicate that an early step in the initiation of humoral immunity is probably an increase in serum CS. This increase in CS is followed by a decrease in circulating lymphocyte and monocyte numbers. These decreases may be the result of lymphocyte trapping in secondary lymphoid organs. This series of events may occur to modulate and activate the immune response.

Animals↗

PubMed1988

Changes in heterophils following antigen injection in immature male chickens.

Eight-week-old Single Comb White Leghorn male chickens were injected intravenously with either .1 mL Brucella abortus (BA) or saline. Blood samples were drawn at 0 and 12 h postinjection and were examined for heterophil numbers and morphology. Differences between numbers of circulating heterophils/mm3 blood were not significant for saline and BA-treated birds at time zero. However, 12 h following injection, heterophil numbers in BA-treated birds were significantly (P less than .05) greater than those in saline-treated birds. Heterophil appearance took two forms: in the first form, granules were small, round, and strongly eosinophilic; in the second form, the granules were large, rod-shaped and more basophilic in staining. These changes indicate the possible involvement of heterophils in the initiation of a humoral immune response through enhancement of some secretory function.

Animals↗

PubMed1987

Relationship between circulating thyroid hormones and cell-mediated immunity in immature male chickens.

The objective of this experiment was to examine the relationship between circulating triiodothyronine (T3), thyroxine (T4) and cell-mediated immunity in immature male chickens. Three week old Single Comb White Leghorn male chicks were used as the experimental animals. In order to produce a wide range of circulating thyroid hormone concentrations, birds were divided into groups and received one of nine treatments including surgical thyroidectomy; 0.1% propylthiouracil (PTU) in the feed; 1 ppm T3 and 10 ppm T4 in the feed. The graft versus host (GvH) response and response to phytohemagglutinin (PHA) were measured at 6 weeks of age. Total and differential white blood cells were counted. Birds were bled, weighed, sacrificed, and the lymphoid organs were removed and weighed. Concentrations of T3 and T4 were measured in the birds from all treatment groups. There were positive correlations between thyroid hormones, mainly T3, and weights of thymus and spleen. T4 but not T3 was positively correlated with number of circulating lymphocytes. There were no significant correlations between circulating T3 and T4 and either PHA or GvH responses. It was concluded that physiological levels of thyroid hormones are needed to maintain normal weights of thymus and spleen and a normal level of circulating lymphocytes. Furthermore, we conclude that lower than physiological levels might be sufficient to maintain normal cell-mediated immunity. Finally, in order to enhance cell-mediated immune responses using thyroid hormones, different doses than were used might be required.

Animals↗

PubMed1987

Effect of photoperiod on the diurnal rhythm of plasma testosterone, dihydrotestosterone and androstenedione in mature male chickens.

1. The effects of different photoperiods on the concentrations of plasma androgens, testes weight and on the diurnal rhythm of plasma testosterone (T), dihydrotestosterone (DHT) and androstenedione (A) in mature, single comb White Leghorn male chickens were studied. 2. Birds were exposed to either 14 hr of light (lights on at 0600-2000 hr) or to 24 hr of light per day. 3. Blood samples were collected from birds in both groups at 3-hr intervals and plasma levels of T, DHT and A were measured using radioimmunoassays. Following blood collection, birds were weighed, killed and testis weights were recorded. 4. Under 14 hr of light, there was a diurnal rhythm of T and DHT with hormone concentrations peaking at the end of the dark period. There was no obvious rhythm for A. Exposure to 24 hr of light abolished the diurnal rhythm found under 14 hr of light. 5. There was an increase not only in testis weights but also in body weight and hormone concentrations under 24 hr of light. 6. It was concluded that photoperiod plays an important role in controlling the concentration and rhythm of androgens in mature male chickens.

Androgens↗

PubMed1986

Relationship between circulating thyroid hormones and humoral immunity in immature male chickens.

The objective of this experiment was to examine the relationship between levels of circulating T3, T4, and humoral immunity in immature male chickens. Three week old Single Comb White Leghorn male chicks were used as the experimental animals. In order to produce a wide range of circulating thyroid hormone concentrations, birds were divided into groups and received one of nine treatments including surgical thyroidectomy; 0.1% propylthiouracil (PTU) in the feed; 1 ppm T3 and 10 ppm T4 in the feed. Antibody production against sheep red blood cells (SRBC) (thymus-dependent antigen) and Brucella abortus (BA) (thymus-independent antigen) was tested at 6 weeks of age. Concentrations of T3 and T4 were measured in birds from each treatment group at 7 and 11 weeks of age. At 11 weeks of age, birds were weighed, sacrificed and lymphoid organs removed and weighed. There were positive correlations between circulating thyroid hormones and weights of bursa of Fabricius and spleens. There were no significant correlations between circulating thyroid hormones and antibody production. It was concluded that physiological levels of thyroid hormones are needed to maintain normal weights of bursa and spleen. Furthermore, we conclude that lower than physiological levels might be sufficient for normal antibody production. Finally, stimulation of antibody production using thyroid hormones may require different doses than what were utilized in this study.

Animals↗