Patricia A. Melrose

Targeted destruction of androgen-sensitive and -insensitive prostate cancer cells and xenografts through luteinizing hormone receptors

We have prepared a conjugate of a lytic peptide (hecate) and a 15‐amino acid segment of the β‐chain of LH to test the concept that this conjugate will target cancer cells expressing LH receptors.

Acute exercises stress modulates immune function in unfit horses

Summary Since exercise stress is associated with multiple changes in immune parameters, we evaluated the effect of acute exercise on 3 indices of immune function in the horse. Six unconditioned thoroughbred horses were subjected to a tread- mill-based exercise challenge. Exerci se intensity was determined by monitoring each horses heart rate, plasma lactate, and cortisol levels. Concurrently, peripheral blood mono- nuclear cells were used to assess pokeweed mitogen (PWM) -induced blastogenesis, influenza-specific proliferation, and lymphokine activated killer (LAK) cell activity. Heart rate peaked during the gallop on an incline while lactate was highest at the end of the stress test (To) with values of 200 bpm and 9 mM/L respectively. Average plasma cortisol was great- est at TO and T+2o with values 76% higher than unstressed horses. Significantly (P

Diurnal changes in specific binding of cortisol to cytosolic and nuclear fractions from equine peripheral blood mononuclear cells

Summary Recent research suggests that the subcellular location and nuclear concentration of glucocorticoid receptors may have a significant impact on cell sensitivity to stimuli acting through cyclic AMP or protein kinase C second messengers. The present study was performed in order to determine whether there may be diurnal fluctuations in the cytosolic and/or nuclear glucocorticoid receptors in equine peripheral blood mononuclear cells (PBMC). Jugular blood samples were collected by venipuncture from four resting unconditioned horses. Samples were collected at 8 AM, 2 PM, 8 PM and 2 AM. The PBMC were harvested from Ficoll gradients. Cytosolic and nuclear fractions were recovered by centrifugation from homogenized PBMC. Protein concentrations of the resulting fractions was determined and serial dilutions incubated with 3H-cortisol in the presence or absence of excess unlabeled dexametha- sone. Saturable specific binding was linear for 75 to 200 µg of protein which was recovered from 10xl0 5 to 100xl0 6 equine PBMCs. This binding was eliminated in heat-treated samples. Further, specific binding of cortisol to cytosolic fractions was reduced (P

Variable effects of proopiomelanocortin peptides on the proliferative response of equine immune cells

Summary Large amounts of proopiomelanocortin (POMC) peptides may be secreted in response to exercise training programs and various physical and psychological stressors. These peptides are also frequently released from hyperplastic pituitary tissues, pituitary adenomas and as part of the endogenous response to various infectious diseases. Work largely performed in other species indicates that the POMC peptides may have dramatic effects on immunological function and related resistance to disease. The present study tested the effects of selected POMC peptide fragments on equine immune cells in order to gain a better understanding of related neuroimmunological interactions in the equine species. Peripheral blood mononuclear cells (PBMCs) and peripheral Tcells were collected from mature Thoroughbreds (n=6). Unconditioned animals were stalled and samples collected between 7 and 9 AM. 5 Quadruplicate wells of 2 X 10 cells were cultured with suboptimal phytohemagglutinin (PHA) in the presence or absence of 10 -5 , 10 -7 , 10 -9 and 10 -11 M hormone concentrations. Hormone treatments included synthetic adrenocorticotropic hormone (ACTHI.39; A39/ ACTH), camel-β-endorphin (β-E), α-melanocyte-stimulating hormone (αMSH), ACTH 1-24 (A1), ACTH4.10 (A4) and ACTHl 18-39 (A18). Hormone or vehicle and mitogen were added at the beginning of culture and the proliferative response was measured on day 3. Results were analyzed by ANOVA and means compared with LSD analysis. The proliferative response of PBMCs from geldings was reduced (P -5 A39/ACTH and A18 treatments. The 10.9 M A39/ACTH treatment stimulated (P -5 to 10.9 M dosages of all truncated ACTH fragments and the 10 -5 M A39/ACTH treatment. T cell proliferation was stimulated (P -7 M to 10 -9 M A1 and the 10 -5 M β-E treatment. T cell proliferation was inhibited by (PP -5 and there was no effect of the remaining treatments. Results from this experiment indicate that POMC peptides and various ACTH fragments may function to regulate proliferation of equine immune cells. The response of PBMCs may be mediated by distinct receptors since A18 extends outside of the core tetradecapeptide sequence normal- ly associated with ACTH effects. Further, the response of equine immune cells to truncated ACTH fragments suggests that peptides released in response to infection may act to coordinate the immunological response. Further work is needed to characterize the physiological significance of these effects.

Cellular distribution of immunoreactive somatostatin in the basal forebrain of horses and ponies

Summary In other experimental models, somatostatin (SRIF) helps coordinate central nervous system (CNS) activity associated with the response to stress. It also plays an important role in the effects of exercise, stress and bacterial infections on growth hormone (GH) release and it may interact with specific SRIF receptors found on lymphocytes. Pituitary GH is a potent immunomodulatory hor- mone which is important to normal function of the thymus and a wide range of immune defense mechanisms. This experiment mapped the distribution of immunoreactive (ir) SRIF in the basal forebrain of horses and ponies. Results are compared to those for other species in order to determine if the anatomical substrate for stress-dependant SRIF effects may be similar to that described for other animal models. Immersion fixed brain tissues were obtained from animals submitted for euthanasia and/or necropsy. Alternate sections were stained for ir-SRIF using characterized polyclonal SRIF antibody and the peroxidase-anti-peroxidase technique, as previously described. Distribution of SRIF cells and fibers was mapped on projection drawings following light microscopic examination. Tissues in this analysis included cell groups at the border between the telencephalon and the rostral diencephalon, the hypothalamus, caudate nucleus (n) subthalamus and thalamus. At rostral levels, ir-SRIF was widely dispersed throughout medial tissues. Caudally, pronounced immunoreactivity was found in ventromedial tissues. Reactive perikarya were localized in the caudate n, olfactory tuberculum, n of the lamina terminalis, rostral preoptic n, suprachiasmatic n, periventricular n, supraoptic n, paraventricular n, arcuate n and ventromedial n. Numerous SRIF fibers extended into the lateral septum, all preoptic n, paraventricular n, rostral hypothalamic n, dorsomedial n, ventromedial n and mammillary n. Reactive fibers were also found in midline thalamic n, perifomical areas, the zona incerta and the habenular n. This distribution is similar to that described in most vertebrates. It reflects the role of SRIF in multiple neurocrine interactions as well as its neuroendocrine activity. Results from this experiment suggest that equine SRIF is likely to participate in neural and endocrine pathways similar to that for other mammalian species. Similar localization patterns also suggest that the coordination of SRIF cell functions within the equine CNS may be comparable to that in other species. This suggests that studies in other species are likely to facilitate the characterization of control mechanisms for SRIF secretion in the equine species.