Max S. Amoss

Equine Laminitis: A Potential Model of Raynaud's Phenomenon

Raynauds phenomenon (RP) and equine laminitis in the horse are medical enigmas. Clinical and scientific data were compared to evaluate the degree of similarity that exists between these two peripheral vascular diseases. Data indicate that certain pathologic and pharmacologic aspects seem to have common features. Some of the correlations maybe due simply to both diseases having ischemia of the distal digits as a pathologic component. The exact etiology of the ischemia is not known for either disease. The results of this study suggest the hypothesis that RP and laminitis are the same disease in different species. This hypothesis can be tested more efficiently when the pathophysiology of both conditions is better documented. It is possible that comparative studies will promote advances in the understanding of both RP and laminitis. The fact that equine laminitis can be experimentally induced is of potential value in such future studies.

Basal and stress-induced corticosterone levels in olive ridley sea turtles (Lepidochelys olivacea) in relation to their mass nesting behavior.

Adrenocortical responsiveness to turning stress was examined in wild, reproductively-active olive ridley sea turtles (Lepidochelys olivacea) in relation to their mass nesting (arribada) behavior. We hypothesized that the high sensitivity threshold (HST) observed in ovipositing sea turtles is associated with a diminished sensitivity of the hypothalamo-pituitary-adrenal (HPA) axis to stressful stimuli in arribada females. We tested this hypothesis by determining whether arribada females exhibited an increased activation threshold of the HPA axis to an imposed stressor (turning stress). Mean basal corticosterone (B) and glucose levels were below 1.0 ng/ml and 60 mg/dl, respectively. Basal B remained unchanged throughout a 24-hr period in basking females. Most animals responded to turning stress with elevated mean B levels (up to 6.5 ng/ml after 6 hr) and no increase in circulating glucose. Nearly 50% of females (and none of the males) were refractory to the stimulation. Males exhibited the most rapid response, with B levels significantly elevated by 20 min over basal levels. Among females, arribada and solitary nesters exhibited a slower rate of response than basking, non-nesting animals. These results demonstrate that olive ridleys exhibit stress-induced changes in circulating B which are slower than those observed in most reptilian and in mammalian, avian, and piscine species. Furthermore, the presence of refractory females and the relatively slower increase in B in arribada and solitary nesters indicate a hyporesponsiveness of the HPA axis to turning stress in nesting olive ridleys. The hyporesponsiveness may be part of a mechanism to facilitate arribada nesting. J. Exp. Zool. 284:652-662, 1999.

Increased levels of arginine vasotocin and neurophysin during nesting in sea turtles

Arginine vasotocin (AVT) and neurophysin (NP) levels were measured by radioimmunoassay in two species of sea turtle, the olive ridley, Lepidochelys olivacea, and the loggerhead, Caretta caretta, during the brief period of nesting and oviposition. In both species, AVT was low in animals which were not reproductively active. AVT was also low at the time animals emerged from the surf to nest, but increased significantly during oviposition and then declined as the animals returned to the water. NP increased in concert with AVT, also reaching highest levels during oviposition. In both species, however, NP levels remained elevated over prenesting levels at the time of return to the water. These findings are consistent with the hypothesis that an AVT-neurophysin complex is released from the neurohypophysis during nesting, and that AVT is a physiological regulator of oviducal contractions in sea turtles.

Sex ratio of immature green turtles inhabiting the Hawaiian archipelago

? 1986. Kinematics of swallowing in the yellow rat snake, Elaphe obsoleta quadrivittata: a reappraisal. Japan. J. Herpetol. 11:96-109. , AND J. E. HAVERLY. 1993. Drinking by the common boa, Boa constrictor. Copeia 1993:808-818. MCDOWELL, S. B. 1972. The species of Stegonotus (Serpentes, Colubridae) in Papua New Guinea. Zool. Meded. Rijksmuseum Nat. Hist., Leiden 47:6-26. MINTON, S. A., JR., AND J. A. ANDERSON. 1963. Feeding habits of the Kukri snake, Oligodon taeniolatus. Herpetologica 19:147. , AND H. B. BECHTEL. 1958. Another Indiana record of Cemophora coccinea and a note on eggeating. Copeia 1958:47. 80. Evolutionary patterns in adv nced MORI, A., N. NARUMI, AND K. V. KARDONG. 1992. Unusual defensive behavior in Oligodon formosanus (Serpentes: Colubridae): head-slashing and tailstriking. J. Herpetol. 26:213-216. SAVITZKY, A. H. 1981. Hinged teeth in snakes: an adaptation for swallowing hard-bodied prey. Science 212:346-349.

Swine leukocyte antigen (SLA) diversity in Sinclair and Hanford swine.

The swine leukocyte antigen (SLA) haplotype B is associated with increased penetrance of the tumor traits in Sinclair swine cutaneous melanoma (SSCM). We established a series of SinclairxHanford swine crosses to facilitate genetic mapping of the tumor-associated loci. In this study, the SLA diversity in the founding animals was characterized for effective selection of maximum tumor penetrance in the pedigrees. Using the sequence-based typing (SBT) method we identified a total of 29 alleles at five polymorphic SLA loci (SLA-1, SLA-3, SLA-2, DRB1 and DQB1) representing six class I and five class II haplotypes. We subsequently developed a rapid PCR-based typing assay using sequence-specific primers (PCR-SSP) to efficiently follow the SLA types of the crossbred progeny. In a total of 469 animals we identified three crossovers within the class I region and three between the class I and class II regions, which corresponded to recombination frequencies of 0.39% and 0.56%, respectively. We also confirmed the presence of two expressed SLA-1 loci in three of the class I haplotypes and were able to determine the relative chromosomal arrangement of the duplicated loci in two haplotypes. This study furthers our understanding of the allelic architecture and polymorphism of the SLA system and will facilitate the mapping of loci associated with the expression of SSCM.

Genetic determinants of cutaneous malignant melanoma in Sinclair swine

The role of genetic factors involved in the determination of risk of cutaneous malignant melanoma (CMM) in humans remains unclear owing to genetic heterogeneity and reliance on simplistic models of inheritance. Here, we report a statistical genetic analysis of cutaneous malignant melanoma in Sinclair swine (SSCM), a unique animal model for human CMM. Using complex segregation analysis a two-locus model involving an unknown major locus and a second locus that lies within or close to the swine leukocyte antigen (SLA) complex jointly determine risk of SSCM in pedigreed animals. These loci also influence severity of affection, accounting for approximately 20% of the phenotypic variation in quantitative tumour burden.

Serum progesterone, estradiol-17β, and glucocorticoids in the collared peccary during gestation and lactation as influence by dietary protein and energy

Sixteen pregnant collared peccaries were assigned to four experimental diets representing two levels of crude protein and two levels of digestible energy. Serum levels of progesterone, estradiol-17 beta (E2), and glucocorticoids were measured by radioimmunoassay. There was no significant dietary effect (P greater than 0.05) associated with any hormone during gestation. Progesterone did not differ between days 11 and 140 of gestation (X +/- SE = 36.48 +/- 1.11 ng/ml, N = 72), began to decline during the last week prepartum, and continued to decline within 24 hr of birth. Glucocorticoid concentrations remained level throughout gestation (X +/- SE = 6.57 +/- 0.45 microgram/dl, N = 74). E2 levels were low during the first 90 days of gestation, rose significantly (P less than 0.001) from 10.11 +/- 1.73 pg/ml (X +/- SE, N = 8) at Days 81-90 gestation to 49.07 +/- 12.87 pg/ml (N = 3) at 2-4 days prepartum (Days 141-147 of gestation), and declined rapidly to baseline levels within 24 hr of farrowing. Litter size had no effect on progesterone or E2 concentrations. There was no significant dietary effect on litter size or gestation length. During lactation, glucocorticoids and E2 remained stable and did not differ by diet, while progesterone concentrations appeared to be affected by diet. Individuals on the high energy-high protein diet returned to normal ovarian function before animals on the other three diets. Results indicated that the pregnant collared peccary can maintain a reproductive steroid environment that allows for fetal development in the face of moderate caloric or protein restriction and that the lactating peccary can undergo a postpartum ovulation in the presence of good nutrition.

Physiological responses of the adult male collared peccary, Tayassu tajacu (tayassuidae), to severe dietary restriction

Metabolic and hormonal responses of eight adult male collared peccaries (Tayassu tajacu) to an ad libitum diet intake, or 25% of an ad libitum intake, were examined. Blood samples for hematological, serum-biochemical and hormonal profiles were collected at three week intervals during the nine week experiment starting 4 August 1983. Males fed on the restricted diet lost an average of 26% of their body weight during the trial, compared to a slight weight gain for those fed ad libitum. Characteristics of the red and white blood cell populations were not influenced by diet intake, with the exception of mean corpuscular volume, which was consistently lower amongst males fed on the restricted diet. Restricted food intake resulted in significantly elevated serum values for urea nitrogen, urea nitrogen:creatinine, urea index, alpha globulin:beta globulin, gamma globulin:albumin, nonesterified fatty acids, alkaline phosphatase and lactate dehydrogenase isozymes (LD1 and LD2). Restricted food intake resulted in significantly lowered serum values for total alpha globulin, alpha-1 globulin, total beta globulin, beta-1 globulin, beta-2 globulin, glucose, triglycerides, calcium, magnesium, sodium, chloride, copper and triiodothyronine. Serum levels of creatinine, total protein, albumin, alpha-2 globulin, uric acid, total bilirubin, cholesterol, aspartate aminotransferase, alanine aminotransferase, gamma glutamyltransferase, lactate dehydrogenase, phosphorus, calcium:phosphorus, potassium, iron, zinc and thyroxine were unaffected by diet intake level. Semen evaluation indicated spermatogenesis was not affected by dietary restriction despite reductions in scrotal circumference and ejaculate gel volume. Serum testosterone levels were significantly lower among males fed on the restricted diet after nine weeks. These data suggest male libido might be depressed during poor range conditions, while maintenance of spermatogenesis might permit them to take immediate advantage of improved range conditions. Blood analysis of metabolic and hormonal function can provide useful information for predicting the adult males nutritional and reproductive condition.

Immunophenotypic characterization of tumor infiltrating lymphocytes and peripheral blood lymphocytes isolated from melanomatous and non-melanomatous Sinclair miniature swine

Selectively-bred Sinclair miniature swine exhibit a high incidence of congenital malignant melanoma which either proves fatal (10-15% of tumor-bearing piglets) or spontaneously regresses with a biphasic immunological phenomenon (85-90%) and no recurrence of malignancy. Mononuclear leukocytes were isolated from cutaneous melanomas and peripheral blood specimens collected from melanomatous (tumor-bearing) Sinclair swine during second-phase regression, and from peripheral blood specimens collected from non-melanomatous (tumor-free) Sinclair swine and control Hanford swine. Leukocyte identities were determined with single- and dual-parameter indirect immunofluorescence assays via flow cytometry. Assays for the specific surface antigens CD45, CD2, CD4, CD8, CD1, MHC class II, and N1 were employed to develop immunophenotypic profiles within the gated lymphocyte clusters from each TIL and PBL suspension. Significantly more CD8+ T-lymphocytes were identified in TIL suspensions than in peripheral blood leukocyte (PBL) suspensions (P < and = 0.05), regardless of breed or tumor status. Conversely, PBL suspensions contained significantly higher percentages of CD4+ T-lymphocytes than the levels found in TIL suspensions (P < and = 0.05). Virtually all TIL were MHC class II+, whereas the percentages of PBL expressing this antigen were markedly lower (P < and = 0.05). The percentages of T-lymphocytes co-expressing CD4 and CD8, a normal subset unique to swine, were generally consistent in all TIL and PBL suspensions examined. The results of this study have firmly established the immunophenotypic identities of cells associated with the second-phase regression phenomenon of this melanoma and have identified specific variations in the leukocyte profiles of the respective TIL and PBL suspensions.

Establishment and characterization of four Sinclair Swine cutaneous malignant melanoma cell lines

Cutaneous malignant melanoma of Sinclair Swine (SSCM) is a heritable, congenital neoplasm which either proves fatal to the neonatal animal or undergoes spontaneous regression. Four SSCM cell lines, UISO-SSCM-433, UISO-SSCM-438, UISO-SSCM-5052, and UISO-SSCM-8093, were derived from biopsy specimens of primary tumors removed from swine at 26, 8, and 8 weeks of age, and 15 weeks gestation, respectively. Morphologic features, DOPA oxidase staining, and abnormal karyotype were suggestive of malignant melanoma. Each cell line was morphologically heterogeneous in culture with dendritic, spindle- and cuboidal-shaped cells. Pigmented melanosomes and DOPA oxidase activity were present in all cell lines at passages 20-22. UISO-SSCM-433 and UISO-SSCM-5052 contained hypodiploid and hypotetraploid sublines whereas UISO-SSCM-438 and UISO-SSCM-8093 were hypodiploid and hypotetraploid, respectively. At later passages, all cell lines presented evolutionary, karyotypic changes; the same chromosomes were involved in the alterations, however. Chromosomes 2, 6, 13, and 14 were the most affected, exhibiting numerical and structural alterations in all four cell lines. Despite the presence of multiple chromosomal anomalies in all cell lines, each with a unique set of chromosomal markers, clonal growth was not detected in soft agar, nor were any of the lines tumorigenic following s.c. inoculation in athymic mice. This suggests that the loss of malignant potential in SSCM may be inherent.