Biomedical subjects

S D Holladay

Publications and source records attributed to S D Holladay.

At least 55 records · Page 3Linked to original sources

PubMed1995

Benzo[a]pyrene-induced alterations in total immune cell number and cell-surface antigen expression in the thymus, spleen and bone marrow of B6C3F1 mice.

Although considerable evidence suggests that carcinogenic polycyclic aromatic hydrocarbons are immunosuppressive compounds, limited information is available regarding precise effects of these agents on immune cells. In the present report, the effect of subchronic exposure to benzo[a]pyrene (B[a]P) on immune cells in bone marrow, thymus and spleen of B6C3F1 mice was investigated. B[a]P treatment was found to reduce thymic cellularity and also to significantly alter normal thymocyte differentiation, as indicated by expression of CD4 and CD8 cell-surface antigens. Exposure to B[a]P also reduced cellularity of the bone marrow, including decreased percentage and absolute number of CD45R+ B-lineage lymphocytes. Further, B[a]P treatment dramatically increased the percentage of CD44hi cells in bone marrow, while proportionately reducing CD44lo cells. These results may indicate CD44lo bone marrow cells, including prolymphocytic cells, represent sensitive targets of B[a]P. The spleens of treated mice were found deficient in both Thy 1.2+ T lymphocytes and CD45R+ B lymphocytes, effects that correlate well with the chemical-induced alterations observed in thymus and bone marrow, respectively.

Animals↗

PubMed1994

Fetal hematopoietic alterations after maternal exposure to ethylene glycol monomethyl ether: prolymphoid cell targeting.

Ethylene glycol monomethyl ether (EGME), which is extensively used in the chemical industries, has been associated with hematologic disorders in both humans and experimental animals. EGME is metabolized to the active compound methoxy-acetic acid (MAA), which readily crosses the placenta and impairs fetal development. However, little is known about the effect of maternal EGME exposure on the development of fetal immunity. In the present report, in utero treatment with EGME was found to alter expression of murine thymocyte and liver fetal cell-surface markers. Pregnant mice were exposed to 100, 150, or 200 mg/kg EGME from gestational days (gd) 10 to 17 and offspring examined on gd 18. Significant thymic atrophy and cellular depletion were found in EGME-exposed fetal mice. Flow cytometric analysis indicated that EGME treatment resulted in decreased percentages of CD4+8+ thymocytes and increased percentages of CD4-8- thymocytes. In vitro exposure to MAA did not result in decreased thymocyte viability or proliferation. These data suggest that EGME, in addition to producing thymic hypocellularity, may inhibit thymocyte maturation. EGME also reduced the percentage of CD45+ leukocytic cells present in fetal liver, an alteration that appeared to be largely manifested by decreased numbers of CD45R+ and CD44dim prolymphoid cells. In vitro MAA exposure of fetal liver cells enriched for lymphoid precursors resulted in significant inhibition of proliferation. Reconstitution of irradiated hosts with gd 18 fetal liver cells from vehicle and EGME-exposed syngeneic donors demonstrated impaired ability of the EGME-treated fetal liver to repopulate the host spleen with B or T lymphocytes. These data suggest that EGME-induced immunosuppression may result from targeting of multiple hematopoietic compartments. Further, the present data indicate that fetal liver prolymphocytes may represent sensitive targets of EGME exposure.

Acetates↗

PubMed1994

Hematopoietic alterations after exposure to T-2 mycotoxin.

Adult mice were exposed by oral gavage to 0.75, 1.25, or 1.75 mg/kg body weight T-2 mycotoxin for 5 consecutive days. Thymic atrophy on the 2nd day following cessation of dosing was profound, and was characterized by significant decreases in the total number of cells within all phenotypes defined by CD4 and CD8 cell-surface antigen expression. Further, the distribution of thymocytes within these phenotypes was significantly altered. Increased percentages of CD4-8- (DN) and decreased percentages of CD4+8+ (DP) cells in thymuses from treated animals suggested that T-2 toxin may inhibit thymocyte maturation. In addition to thymus, the bone marrow of treated animals showed a highly significant hypocellularity, indicating that this hematopoietic compartment may also be targeted by T-2 toxin. A trend toward reduced splenic cellularity was additionally observed in exposed animals, but failed to reach significance. A significant decrease in the total number of both B and T-lymphocytes present within the spleen was observed, however. These data, taken together, indicate that effects at multiple hematopoietic compartments involved in the production of T-lymphocytes may contribute to the peripheral T-cell lymphocytopenia and T-cell mediated immunosuppression produced by T-2 toxin.

Administration, Oral↗

PubMed1994

Fetal hematopoietic alterations after maternal exposure to benzo[a]pyrene: a cytometric evaluation.

In utero exposure to the environmental contaminant benzo[a]pyrene (BaP) was found to alter expression of murine thymocyte and liver fetal cell-surface markers. Pregnant mice were treated (via gavage) with 0, 50, 100, or 150 mg BaP/kg/d on gestational days (gd) 13-17, and offspring were examined on gd 18. Severe thymic atrophy and cellular depletion were found in BaP-exposed fetal mice. Flow cytometric analysis indicated that the BaP treatment resulted in a significant decrease in the percentage of CD4+8+ fetal thymocytes, as well as significantly increased CD4-8- and CD4-8+ thymocytes. Staining of thymocytes with anti-mouse heat-stable antigen (HSA) and CD8 monoclonal antibodies produced similar results. These data suggest that BaP, in addition to producing thymic hypocellularity, inhibits normal thymocyte maturation processes. The BaP treatment was also found to decrease total fetal liver cellularity including numbers of cells within resident hematopoietic subpopulations. In particular, prolymphocytic cells, identified by CD44 and CD45R antigen expression and by presence of nuclear terminal deoxynucleotidyl transferase (TdT), were significantly decreased in animals gestationally exposed to BaP. These data, taken together, indicate that postnatal suppression of cell and humoral-mediated immune function following in utero exposure to BaP may result from multiple targeting of immune cells at different hematopoietic levels. Furthermore, results of the present study identify both qualitative and quantitative changes in fetal immune cell antigen expression that correlate well with the postnatal immunosuppression that occurs in experimental animals exposed to this carcinogenic polycyclic aromatic hydrocarbon.

Animals↗

PubMed1993

Selective prothymocyte targeting by prenatal diethylstilbesterol exposure.

Estrogens have been reported to modulate immunologic responses at both physiologic and pharmacologic concentrations. Treatment of experimental animals with the synthetic estrogen, diethylstilbesterol (DES), markedly decreases thymic cellularity, manifested histologically as a progressive loss of cortical thymic lymphocytes. In the present report thymic atrophy after prenatal DES exposure was found to be more severe than has been reported following adult exposure, indicating a possible greater sensitivity of the developing immune system to estrogenic hormones. DES exposure resulted in a limited alteration of cell maturation within the fetal thymus as evidenced by only slight alterations in the expression of CD4 and CD8 cell-surface antigens. To examine the possibility that DES targets hematopoietic stem cells in the fetal liver, cytometric analysis was conducted using a panel of fluorescent antibodies to quantitate the hematopoietic subpopulations present in control and DES-exposed Gestational Day (gd) 18 fetal mouse liver. There were no significant DES-induced alterations in the number of hematopoietic stem cells, or in fetal liver cells expressing CD44 (hematopoietic precursors), Mac-1 (granulocyte-macrophage lineage precursors), or CD45R (B-lineage lymphocytes) surface antigens. However, DES selectively reduced the number of fetal liver precursors containing the lymphocyte stem cell-specific DNA polymerase, terminal deoxynucleotidyl transferase, which suggested that DES may specifically target the fetal liver prothymocyte. Reconstitution of irradiated hosts with gd 18 fetal liver from vehicle and DES-exposed syngeneic donors demonstrated an impaired ability of the DES-treated fetal liver to repopulate the thymus of irradiated hosts. In addition, fetal liver cells enriched for prelymphoid cells contained potentially significant levels of estrogen specific receptors. Taken together these data, in conjunction with the lack of direct thymocyte injury (necrosis, apoptosis, and/or inhibition of cell proliferation) by DES treatment, suggest that estrogen-mediated thymic atrophy may result, at least in part, from a specific alteration in the lymphocyte stem cell population responsible for colonizing the thymus.

Animals↗

PubMed1993

Fetal thymic atrophy after exposure to T-2 toxin: selectivity for lymphoid progenitor cells.

Treatment of experimental animals with T-2 toxin has been found to markedly decrease thymic cellularity and to suppress cell-mediated immune function. Although T-2 toxin readily crosses the placenta, little is known about its effect on development of immunity following gestational exposure. In the present report, prenatal T-2 toxin resulted in significant fetal thymic atrophy in mice. In vitro exposure to T-2 toxin resulted in decreased thymocyte proliferation, as well as significant but transient increases in thymocyte viability. Cycloheximide increased thymocyte viability parallel to that seen after T-2 toxin, indicating that enhanced viability after T-2 toxin may be the result of inhibited endonuclease synthesis. These findings suggest that direct cytotoxic effects of T-2 toxin make limited contribution to thymic atrophy production. In support of this conclusion, in vivo T-2 toxin exposure resulted in only limited alteration of thymocyte development, as evidenced by expression of CD4, CD8, and alpha beta TCR cell-surface antigens. These data further indicate that antiproliferative effects of T-2 toxin on thymocytes may contribute limitedly to thymic atrophy observed in vivo. In vivo T-2 toxin treatment did not affect total numbers of CD44+, CD45+, or Mac-1+ fetal liver cells. However, such exposure resulted in significant decreases in CD44lo and CD45lo fetal liver prolymphoid cell subpopulations. Subsequent in vitro T-2 toxin exposure of fetal liver cells enriched for lymphoid precursors resulted in both decreased cell viability and highly significant decreased proliferation. Taken together, these data suggest that lymphocyte progenitors, in contrast to thymocytes, represent highly sensitive targets of T-2 toxin exposure, responsible for thymic atrophy.

Animals↗

PubMed1993

An additional bone in the carpal region of raptorial birds.

In a series of 4 species of owls and 12 species of diurnal raptors, an additional bone was present bilaterally in the area of the carpus. Designating the bone as an "additional bone of the raptorial carpal region" is suggested pending appropriate embryological studies to determine the origin of the bone. Generally, the bone was present in owls and in diurnal raptors with relatively short, rounded wings, but was absent in species with longer, more tapered wings. The bone lies at the cranial edge of the carpal area near the radial carpal bone, and is fixed to the surrounding skeleton by ligaments. The tendon of the tensor patagium longus muscle has one slip that attaches to the additional bone and another that passes over its craniodorsal surface en route to insertion. Awareness of the occurrence of this bone in some raptors, but not others, is essential in clinical evaluation of wing injuries, as well as in forming a prognosis for the return to soundness, the potential for release, and, therefore, the life of an injured raptor.

Animals↗

PubMed1992

Exposure to tetrachlorodibenzo-p-dioxin (TCDD) alters fetal thymocyte maturation.

We previously reported that thymic atrophy and reduced thymic cellularity associated with prenatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice are characterized by quantitative alerations in the number of thymocytes expressing CD4 and CD8 surface antigens. In the present study, these observations have been extended to establish the specific thymocyte maturation processes affected by TCDD through an examination of cell size distributions, alpha beta and gamma delta T cell receptor (TCR) expression, peanut agglutinin (PNA) binding, and J11d marker analysis in murine thymocytes exposed prenatally to TCDD. Pregnant mice were administered vehicle, 1.5 or 3.0 micrograms/kg body wt TCDD by gavage on gestational Days (gd) 6-14. Flow cytometry analysis of gd 18 fetal thymocytes revealed a reduction in the number of small CD4+CD8+ double positive (DP) and PNA+, small thymocytes in the TCDD-exposed groups. The large cell population was reduced by TCDD to approximately 70% of control values. There was also a significant shift in TCR expression of thymocytes with a decrease in alpha beta TCR and a concommitant increase in gamma delta TCR expression from TCDD-exposed fetuses. The CD4-CD8+J11d+ thymocytes were increased in TCDD-treated mice while the more mature CD4-CD8+J11d- thymocyte numbers were similar to controls. Taken together, these data indicate that TCDD inhibits thymocyte maturation at the transition phase between the CD4-CD8+J11d+ phenotype and the DP/J11d+ thymocytes.

Animals↗

PubMed1992

Technical note: preservation of tissues and gastrointestinal tract portions by plastic coating or plastination.

Two methods to preserve gastrointestinal tract (GIT) organs and tissues, plastic coating (PC) and plastination (PN), were investigated and compared. Specimens to be preserved were removed from animals within 2 h of death and immediately cleaned with water. Digesta contents were removed by flushing desired portions of GIT with water until the exiting water was clear. In the PC method, cleaned specimens were dehydrated by immersion in an isopropanol solution, dried with forced air after positioning and orientation as in situ, and finally coated on the outer and inner surfaces with a clear plastic material. In the PN procedure, specimens were filled with, and submerged in, a low-formaldehyde fixative, then dehydrated by immersion in a cold acetone solution. Dehydrated specimens were immersed in silicone and placed in a freeze drier for impregnation under low vacuum, followed by overnight gas curing with a silicone crosslinker. Finally, viewing windows were cut out with a scalpel in GIT preserved by both methods. Preserved GIT and tissues had an appearance similar to their appearance in vivo. The PC method was simple and inexpensive. Plastinated specimens were more flexible, durable, and lifelike than those preserved by the PC method. In addition, many body parts, such as muscles, nerves, bones, ligaments, and central nervous system specimens, were preserved by PN. Both methods were found to be useful tools for postmortem studies of tissues and GIT organs.

1-Propanol↗

PubMed1991

Perinatal thymocyte antigen expression and postnatal immune development altered by gestational exposure to tetrachlorodibenzo-p-dioxin (TCDD).

In utero exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was found to alter expression of murine thymocyte fetal cell-surface markers. Pregnant mice were treated (via gavage) with 0, 1.5, or 3.0 micrograms TCDD/kg/day in corn oil on gestational days (gd) 6-14. Offspring were examined on gd 18 and postnatally on d6, d14, and d21, and at 7, 8, and 10 weeks of age. Severe thymic atrophy and cellular depletion were found both pre- and postnatally in TCDD-exposed mice. Immunocytochemical localization of the Thy 1.2 antigen on gd 18 thymocytes revealed no TCDD-related changes in cellular distribution. Flow cytometric analysis, however, indicated that the TCDD treatment resulted in a significant decrease in the percentage of CD4+8+ fetal thymocytes, as well as significantly increased CD4-8- and CD4-8+ thymocytes. The increased CD4-8+ population after TCDD was not from induction of Ts cells. At 7-8 weeks postnatally, no differences existed between control and treatment groups in mitogen responses and antibody plaque response. However, altered thymocyte antigen expression was found to correlate with altered postnatal immune function, as evidenced by decreased cytotoxic T lymphocyte response at 8 weeks of age. Taken together, these results indicate that immunosuppression following prenatal exposure to TCDD can be readily detected by qualitative and quantitative changes in the cell surface phenotype of fetal thymocytes. Furthermore, the observed altered distribution suggests that TCDD inhibits normal thymocyte maturational processes.

Animals↗

PubMed1991

Evaluation of an indirect enzyme-linked immunosorbent assay for screening antibody against aflatoxins.

Enzyme-linked immunosorbent assay screening of antibody produced against aflatoxin was accomplished by a new and simple procedure. To demonstrate the new indirect ELISA technique used, antibody against aflatoxin M1 was produced in female BALB/CJ mice by immunization with an aflatoxin M1-bovine serum albumin conjugate. Instead of coating test-plate wells with purified antibody (direct ELISA) or synthesizing a second protein-aflatoxin conjugate (aflatoxin M1-poly-L-lysine) to coat test-plate wells, wells were coated with the readily available aflatoxin M1-bovine serum albumin and aflatoxin B1-bovine serum albumin. This method, applicable for any aflatoxin conjugated by the common cyclopentano-carboxymethoxyl-oxime technique, eliminates the more time-consuming and technically difficult portions of earlier direct and indirect ELISA. The new technique can be valuable in continued efforts toward development of new and improved immunoassays against aflatoxin metabolites.

Aflatoxins↗

PubMed1990

Absence of an osseous patella and other observations in Macropodidae stifle.

The patella is a large sesamoid bone that typically develops in the tendon of insertion of the large extensor muscles of the stifle joint. Although present in almost all species of mammals and birds, it has been found to be absent in the red kangaroo and two wallaby species (family Macropodidae). In its place is a fibrocartilage pad, located in the tendon of the quadriceps femoris muscle. This structure is visible grossly, is palpable, and has the form normally expected of a bony patella. In addition, the femoral trochlea is shallow and asymmetric, and the lateral gastrocnemius sesamoid is unusually prominent. These and other related modifications in the area of the Macropodidae stifle are presented.

Animals↗

PubMed1990

A simplified method of casting the macroscopic airways of lungs.

A technique for preparing casts of the macroscopic airways of mammalian lungs, which is both simplified and inexpensive in comparison with previous techniques, is described. The models are accurate, durable and flexible, and clearly demonstrate the orientation and branching pattern of the bronchial tree. The nature of the procedure also extends the availability of casts to laboratories or individuals with limited instrumentation and/or funding. Preliminary results using this technique to inject the lungs and certain air sacs of birds are also discussed.

Animals↗

PubMed1989

Preparation of protein conjugatable aflatoxin oxime derivative from significantly reduced starting quantities.

A modification of an existing technique for the preparation of aflatoxin B1-(0-carboxymethyl) oxime is presented which allows for a significantly reduced starting amount of aflatoxin. About 80% of the aflatoxin was converted to its oxime. The new technique will be particularly valuable when protein conjugatable oximes of more expensive aflatoxin metabolites, such as aflatoxin M1, are required for immunoassay production.

Aflatoxin B1↗

PubMed1987

Effect of cage density and rank in peck order on brain regional monoamines in adult male Coturnix coturnix japonica.

1. In adult male Coturnix coturnix japonica neither norepinephrine (NE) nor serotonin (5HT) in various brain regions were affected by caging density (174 cm2-8/cage; 348 cm2-4/cage; 696 cm2-2/cage). Dopamine (DA) in diencephalon was elevated in high density cages. 2. Peck order rank was assigned on the basis of feather distribution on head, neck and back and lesions on head and back. 3. Upper strata peck order rank was associated with significantly lower levels of brain regional NE and DA compared to lower strata peck order rank. 4. Peck order rank did not affect brain regional 5HT. 5. The results indicate significant individual behavioral-neuroendocrine interaction leading to reproductive dysfunction.

Animals↗

PubMed1987

Effect of caponization on central nervous system monoamines in the Japanese quail.

Depletion of brain regional norepinephrine (NE), dopamine (DA) after alpha methyl-paratyrosine (AMT), and serotonin (5HT) were measured in intact and caponized adult male Japanese quail (Coturnix coturnix japonica). Telencephalon, diencephalon, and cerebellum DA was depleted by AMT treatment, but brain stem was not affected. AMT-induced depletion of NE was greatest in telencephalon, diencephalon, and brain stem of capons. Neither caponization nor AMT affected brain regional 5HT. The results from this work indicate that caponization will affect catecholamine dynamics in brain regions other than the hypothalamus.

Animals↗

PubMed1986

Preparation of flexible models of hollow gastrointestinal organs.

Flexible models of hollow gastrointestinal organs can be easily prepared by coating air-dried organs with a commercially available clear plastic compound. The plastic infiltrates the full thickness of organ walls to support and protect internal as well as external structures. Models are flexible, resistant to fluids, and lightweight. This plasticizing technique is particularly useful for the preservation and study of large animal gastrointestinal tracts.

Animals↗

PubMed1983

Grouping in Japanese quail. 1. Agonistic behavior during feeding.

Agonistic behavior in male Japanese quail, shown by aggressive pecking after feed restriction, was potentiated in unstable groups (a visitor bird moved to a new cage containing an unfamiliar resident each 24-hr period) but not in stable (a pair that was never changed once the birds were placed in cages) groups. The resident quail were more aggressive than either visitors or individuals of the stable groups. Ambivalent behavior (behavior characterized by an aggressive action followed immediately by a submissive posture) during feeding competition was observed in both the unstable and stable groupings. The ambivalent behavior appeared to be a conditioned response and was probably a result of the motivation to feed after a period of feed deprivation. During the experimental period the stable pairs of quail gained 28% of their initial body weight, but the resident and visitor quail, which were in the unstable grouping, gained only 15 and 13%, respectively. The differences in percentage weight gain were significant. Paired testes weights of the resident and visitor quail were significantly less than those of the stable birds.

Aggression↗