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Biomedical subjects

L C Ellis

Publications and source records attributed to L C Ellis.

At least 19 recordsLinked to original sources
PubMed1999

Effects of bull exposure on postpartum ovarian activity of dairy cows.

The effects of bull exposure on postpartum reproduction have been previously studied in beef, but not in dairy cattle. The objective of this experiment was to investigate effects of bull exposure on postpartum reproductive characteristics during early lactation in high-producing Holstein dairy cattle. Forty-five multiparous dairy cows (9764 +/- 140 kg milk/lactation) were randomly grouped at the time of calving. Treatment 1 (NBE) was never exposed to the bull, treatment 2 (2 x BE) experienced fenceline contact with a mature Holstein bull twice daily during routine detection of oestrus, and treatment 3 (CBE) was in continuous proximity to the bull. All cows were observed for oestrous behaviour twice daily for 1/2 h following milking. Blood samples were collected every other day for progesterone (P4) assay. Postpartum ovarian reactivation, indicated by the occurrence of the first sustained rise in P4, was later (P = 0.02) during the postpartum period in both bull-exposed (2 x BE, CBE) treatments compared to the NBE treatment. Time postpartum until completion of the first ovarian cycle tended (P = 0.08) to be shorter in NBE cows compared to bull-exposed cows. Peak P4 concentrations were higher (P = 0.05) in NBE cows compared to bull-exposed cows prior to the second postpartum ovulation. Results indicate an extended period to ovarian reactivation in dairy cattle exposed to a bull, but bull exposure had no effect on long-term reproductive performance of exposed cows.

Animals↗
PubMed1997

Prolactin-induced termination of obligate diapause of mink (Mustela vison) blastocysts in vitro and subsequent establishment of embryonic stem-like cells.

The mink reproductive cycle includes an obligatory period of embryonic diapause and delayed implantation, which continues in vitro and reduces the efficiency of embryonic stem (ES) cell establishment. Blastocysts recovered on day 7 and on days 13-16 after final mating were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with various concentrations of prolactin to determine optimal conditions for embryo attachment and subsequent establishment of embryonic stem cells. Five treatments were applied to both ages of blastocyst: A, DMEM control (n = 16); B, DMEM + 5 micrograms prolactin ml-1 after 10 days initial culture in DMEM alone (n = 17); after 1 day of initial culture: C, DMEM + 10 ng prolactin ml-1 (n = 17); D, DMEM + 1 microgram prolactin ml-1 (n = 19); and E, DMEM + 5 micrograms prolactin ml-1 (n = 17). Prolactin terminated diapause of day 13-16 blastocysts at all concentrations tested. The maximum attachment of embryos in vitro and subsequent production of ES-like cells occurred in medium supplemented with 5 micrograms prolactin ml-1. Prolactin did not affect attachment rates for day 7 blastocysts when 5 micrograms prolactin ml-1 was added, but prolactin at concentrations of 1 microgram ml-1 and 5 micrograms ml-1 when added on day 1 of culture enhanced ES-like cell line establishment. Two principal cell types were observed in the colonies: small stem cells and trophoblast-like cells with large areas of cytoplasm. The morphological evaluation of mink ES-like cell colonies was confirmed by cytochemical staining for alkaline phosphatase. Mink embryonic stem-like cells were found to stain positive for alkaline phosphatase. Alkaline phosphatase activity was lost upon cellular differentiation.

Alkaline Phosphatase↗
PubMed1996

Melatonin reduces mortality from Aleutian disease in mink (Mustela vison).

Aleutian disease (AD) results from a persistent parvoviral infection that results in marked hypergammaglobulinemia and immune complex mediated lesions of the kidney, liver, lungs and, arteries. Melatonin protected both a wild type or demi strain and a demi/dark crossed strain of mink from AD. The biogenic amine also afforded protection against other non-diagnosed diseases naturally found on mink farms when it was available from a subcutaneously-placed reservoir. Some genetic strains of mink apparently differed in the resistance of mink to the virus and in the protective ability of melatonin. The demi strain was the most resistant followed by pastels, mahogany, darks, and those strains with the double recessive Aleutian gene. The protective action of melatonin appeared to result from melatonin's ability to scavenge free radicals, but it could also be due to the induction of antioxidant enzymes or to the modulation of immunity. Melatonin also protected mink against distemper.

Aleutian Mink Disease↗
PubMed1996

Progression of Aleutian disease in natural and experimentally induced infections of mink.

OBJECTIVE: To study temporal changes in amounts of viral DNA in blood leukocytes over long periods, and to determine whether severity of the disease is greater in experimentally induced, compared with natural, infection. ANIMALS: 18 naturally and 6 experimentally infected black mink; 26 naturally infected brown mink. PROCEDURE: Polymerase chain reaction amplification to detect viral DNA in blood and counter-immune electrophoresis to detect serum antibody were performed at regular intervals. RESULTS: In naturally infected black mink, amounts of viral DNA were initially high, but after the appearance of antibody, viral DNA fluctuated and, in some instances, was undetectable. In other mink, small amounts of viral DNA were infrequently detected during the course of the infection. Amounts of viral DNA in leukocytes in late stages of the disease correlated with renal lesions in brown mink, but black mink had more severe lesions associated with smaller amounts of viral DNA. Severity of the disease was not enhanced in experimentally inoculated black mink. CONCLUSIONS: After infection, leukocyte viral DNA is initially present in large amounts, but, in most mink, decreases markedly in association with the appearance of antibody. There is no difference in the progression and severity of the disease between black mink infected experimentally or naturally. Transmission of the disease may be enhanced by use of contaminated toenail clippers for blood collection.

Aleutian Mink Disease↗
PubMed1995

Joint infections due to Listeria monocytogenes: case report and review.

Joint infections of bone are unusual manifestations of listerial infection. Fourteen cases of septic arthritis due to Listeria monocytogenes have been previously described in adults. We report the 15th case of septic arthritis due to Listeria in which bilateral prosthetic hips in a renal transplant patient were involved. In addition, we review the literature on listerial joint infections.

Adult↗
PubMed1995

Postantibiotic effect of clarithromycin alone and combined with ethambutol against Mycobacterium avium complex.

The postantibiotic effect (PAE) of clarithromycin alone and in combination with ethambutol was determined for two clinical blood isolates of Mycobacterium avium complex. An average PAE, ranging from 5.5 to 18.0 h, was noted for each isolate at each clarithromycin concentration except when isolate B was exposed to clarithromycin at the MIC. The addition of ethambutol did not enhance the PAE observed with clarithromycin alone. The clinical implications of the PAE of clarithromycin for M. avium complex remain to be determined.

AIDS-Related Opportunistic Infections↗
PubMed1993

Immunohistochemical localization of tyrosine hydroxylase in corneal nerves.

The sympathetic innervation of the mammalian cornea is thought to play an important role in the regulation of epithelial ion transport, mitogenesis, and wound healing following corneal injuries. Anatomically, the three-dimensional organization and relative density of corneal sympathetic innervation in many species remains inadequately described. In the present study, the sympathetic innervation of five different mammals (guinea pig, rat, mouse, hamster, and human) was studied in corneas sectioned parallel to the main axis of fiber orientation by labeling the fibers immunohistochemically with antiserum against tyrosine hydroxylase and an avidin-biotin-diaminobenzidine technique. The results showed that each species displayed a distinctive pattern and density of tyrosine hydroxylase immunoreactive (TH-IR) corneal innervation that was unique to that species. The overall level of TH-IR innervation was highest in the guinea pig, moderate in the human, hamster, and rat, and lowest in the mouse. In all species examined, TH-IR nerves were most numerous in the corneoscleral limbus where they either formed intimate associations with blood vessels or coursed through the connective tissue matrix apparently unrelated to vascular elements. Other TH-IR nerves entered the cornea proper in radially directed stromal nerve bundles to give rise to subepithelial plexuses of varying complexity. Occasional intraepithelial penetrations were observed in the guinea pig, human, and rat. Removal of the superior cervical ganglion resulted in the total loss of TH-IR staining from guinea pig and hamster corneas and in the substantial but incomplete loss of TH-IR staining from rat and mouse corneas, thus demonstrating their predominantly sympathetic origin. Combined sympathetic and sensory ocular denervation in the rat eliminated almost all corneal and limbal TH-IR immunostaining, thus suggesting a minor TH-IR sensory component in this species. In agreement with this conclusion, small numbers of TH-IR sensory neurons and an abundance of TH-IR fibers were observed in the trigeminal ganglia of the rat and guinea pig. Removal of the rat main ciliary ganglion resulted in the loss of additional TH-IR fibers from the chamber angle and iris, thereby confirming a partial parasympathetic contribution to the rat iridial TH-IR innervation. Following unilateral removal of the superior cervical ganglion in rats and guinea pigs, the contralateral cornea contained increased numbers of TH-IR nerves, suggesting an upregulation of tyrosine hydroxylase (TH) expression in some contralateral axons.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic Fibers↗
PubMed1993

Monoclonal antibodies identifying subsets of ectodermal, mesodermal, and endodermal cells in gastrulating and neurulating avian embryos.

The goal of our laboratory research is to elucidate the mechanisms underlying gastrulation and neurulation, using the avian embryo as a model system. In previous studies, we used two approaches to map the morphogenetic movements involved in these processes: (1) we constructed quail/chick transplantation chimeras in which grafted quail cells could be identified within chick host embryos by the presence of nucleolar-associated heterochromatin, and (2) we microinjected exogenous cell markers. However, it would be advantageous to be able to detect endogenous markers to demarcate various subsets of cells within the unmanipulated embryo. To elucidate such a series of natural markers, we have used monoclonal antibodies to identify epitopes found on subsets of ectodermal, mesodermal, and endodermal cells. Antibodies were made by immunizing mice against either homogenized ectoderm (i.e., prospective neural plate and surface ectoderm) or primitive streak, which had been microdissected from stage 3 chick embryos. Additionally, we screened a panel of antibodies made against soluble protein obtained from isolates of cell nuclei from late embryonic chick brain. Here, we describe the labeling patterns of three monoclonal antibodies, called MAb-GL1, GL2, and GL3 (GL, germ layer), during avian gastrulation and neurulation. Our results show that labeling early avian embryos with monoclonal antibodies can reveal previously undetected distributions of cells bearing shared epitopes, providing new labels for subsets of cells in each of the three primary germ layers.

Animals↗
PubMed1993

Sensory and sympathetic nerve sprouting in the rat cornea following neonatal administration of capsaicin.

Corneal sensory and sympathetic nerves exert opposing actions on corneal mitogenesis and wound healing. The mechanisms by which these nerves exert their actions are unknown; however, the release of axonally transported neuropeptides has been postulated. In the present study, we investigated changes in innervation densities of calcitonin gene-related peptide (CGRP-) and tyrosine hydroxylase (TH-)immunoreactive (IR) nerves of the rat cornea following neonatal capsaicin administration, and the relationships between these changes and the development of neuroparalytic keratitis. Newborn rats were injected with capsaicin on each of the first 3 days of life. Forty-eight hours after the last injection, corneal CGRP immunostaining had totally disappeared from the cornea, whereas TH immunostaining was relatively unaffected. Over the next several weeks, a dramatic reinnervation of the cornea took place. By 6-8 weeks both the CGRP- and TH-IR corneal innervation density in the capsaicin-treated animals exceeded that of age-matched control or normal animals; that is, the corneas had become "hyper-reinnervated." The pattern of innervation that returned was grossly abnormal and was characterized by the presence of a bizarre subepithelial plexus of fine stromal sprouts; an abundance of myelinated axons; and complex, atypical, epithelial leash morphologies. Retrograde transport of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP) from the central cornea in control and capsaicin-treated adult animals labeled an average of 143 and 47 trigeminal ganglion cells, respectively (with mean diameters of 25.7 +/- 0.49 microns and 34.3 +/- 0.72 microns), suggesting a 67% decrease in corneal afferent neurons in the capsaicin-treated animals. Transection of the ophthalmomaxillary nerve in adult capsaicin-treated animals completely eliminated corneal CGRP-IR staining, and extirpation of the superior cervical ganglion resulted in the loss of 70-80% of corneal TH-IR nerves, thus demonstrating the sensory and predominantly sympathetic origins, respectively, of these fiber populations. Chronic keratitis and neovascularization developed in the capsaicin-treated animals by approximately 3 weeks of age, achieved a maximum intensity between 4 and 6 weeks, and showed some gradual improvement thereafter. However, the keratitis never completely disappeared, even after 13 months. In conclusion, these data show that corneal sensory (CGRP-IR) and sympathetic (TH-IR) nerve fibers undergo extensive sprouting following partial corneal sensory denervation with the neurotoxin capsaicin. However, the resultant "hyper-reinnervation" is morphologically abnormal and, for reasons unknown, functionally incapable of preventing or totally reversing the keratitis.

Adrenergic Fibers↗
PubMed1991

The anionic charge barrier in the renal corpuscle of the pronephros in the lamprey, Petromyzon marinus L.

The charge barrier within the renal corpuscle of the pronephric kidney of the lamprey, Petromyzon marinus, was investigated at two life cycle intervals using cationized ferritin and polyethyleneimine. In the larval renal corpuscle the endothelium of the glomerular capillaries and the laminae rarae externa and interna of the glomerular basement membrane show regularly-spaced deposits of the tracers. The lamina densa remains unstained. Concomitant with a loss of major processes of the visceral epithelial podocytes and development of an extensive mesangial matrix in late adult life are alterations in the distribution of the anionic sites. The lamina rara interna is no longer a distinct entity and the mesangium contains irregularly-distributed anionic sites surrounding electron-dense deposits. The results indicate that the distribution of the anionic sites during adult life most likely affects the ability of the renal corpuscle to act as an efficient filtration device. This charge distribution is consistent with that seen during some renal pathologies of higher vertebrates.

Aging↗
PubMed1990

Pronephric regression during larval life in the sea lamprey, Petromyzon marinus L. A histochemical and ultrastructural study.

The regression of the pronephric kidney of the lamprey, Petromyzon marinus, is described using histochemical and ultrastructural techniques. Regression begins in the third year of larval life, and by the time the animal enters metamorphosis the tubules have all disappeared. The nephrostomes and the renal corpuscle, however, persist for the remainder of the life cycle and undergo little change in the larva. Iron is present within the tubular epithelium prior to the beginning of degeneration, but as degeneration proceeds iron is observed within the tubule lumina. Acid phosphatase is noted within the tubule epithelia prior to degeneration, but as degeneration proceeds acid phosphatase is also observed within the intertubular area. Features of tubular regression include a prominent and highly folded basal lamina, numerous cytoplasmic inclusions, and dense bodies in the epithelia and lumina. The intertubular region is invaded by lymphocytes, granulocytes, plasma cells, and macrophages. The process of pronephric regression possesses many features of the process of apoptosis, which has been noted in the regression of larval organs in other vertebrates.

Acid Phosphatase↗
PubMed1989

Ultrastructure of the pronephric kidney in upstream migrant sea lamprey, Petromyzon marinus L.

The pronephric kidneys were examined in upstream migrant sea lampreys, Petromyzon marinus L., by transmission and scanning electron microscopy. Each pronephros consists of an enlarged renal corpuscle (glomus) and ciliated nephrostomes, but there are no renal tubules. The renal corpuscle contains an extensive mesangium, which consists of a highly fibrous extracellular matrix, numerous mesangial cells, granulocytes, and macrophages. The extracellular matrix contains microfibrils with a morphology similar to amyloid P microfibrils, fibrils with a periodicity similar to fibrin, and abundant collagen. Often these fibrillar components are aggregated in the region of the basement membrane, giving it a thickened appearance. Some podocytes of the visceral epithelium appear swollen, and their cytoplasm contains numerous vacuolar inclusions, and many have only primary major processes with only a few or no foot processes. The morphological features of the pronephric kidney of the lamprey at this time in the life cycle reflect the regression of this organ, but some features also resemble those seen in renal pathologies of higher vertebrates.

Animals↗
PubMed1987

Gap junctions and zonulae occludentes of hepatocytes during biliary atresia in the lamprey.

Gap junctions and zonulae occludentes of hepatocytes were examined in thin sections and freeze-fracture replicas from livers of larval and juvenile adult lampreys and during the phase of metamorphosis when bile ducts and bile canaliculi disappear (biliary atresia). Larvae possess zonulae occludentes at the canaliculi which are composed of one to five (mean = 2.81) junctional strands that provide a bile-blood barrier. Morphometry demonstrates that during biliary atresia the decreases in number of junctional strands and apico-basal depth of the zonulae occludentes are accompanied by an increase in the frequency of gaps or interruptions in the strands and in a breakdown of the bile-blood barrier. The zonulae occludentes completely disappear during metamorphosis and are not found in the adult liver. Gap junctions of the larval liver occupy 1% of the surface of the plasma membrane and have a mean area of 0.167 micron 2 but, following an initial decline in these parameters during early biliary atresia, they rise sharply in later stages of metamorphosis and in adults are 3.2% and 0.502 micron 2, respectively. The events of alteration in junctional morphology during lamprey biliary atresia is in many ways comparable to the changes in gap junctions and zonulae occludentes during experimental and pathological intra- and extrahepatic cholestasis in mammals.

Animals↗
PubMed1987

A natural killer cell assay for the mink using a mouse lymphoma as the target cell line.

A natural killer cell assay was developed for the mink (Mustela vison) using mink peripheral mononuclear cells as effector cells and a mouse lymphoma cell line as targets. Baseline levels of natural killer cell activity were established in fertile mutation mink, primary infertile dark mink and secondary infertile dark mink with autoimmune orchitis. Blood samples were taken from dark mink at the end of March and from mutation mink during the first 2 weeks in April. Statistically significant differences in activity were noted between color phases and among groups. The possibility of genetic and/or seasonal differences in natural killer cell activity is discussed.

Animals↗
PubMed1985

Ablation of the blood-testis barrier in rats and guinea pigs by 48/80, a histamine releaser, and cadmium chloride.

When adult male guinea pigs were injected unilaterally intratesticularly with compound 48/80 (1 mg in 0.05 ml saline), their testicular peritubular capillaries were engorged with blood, intratubular edema was present on the ipsilateral side, and the blood-testicular (BT) barrier (measured by the entrance of acriflavin into the seminiferous tubule) was ablated. The contralateral testis, when injected with saline, showed no pathological changes nor a breakdown of the BT barrier. Subcutaneous injection of guinea pigs with cadmium chloride resulted in a more intense intratubular fluorescence than was observed for 48/80-treated animals. The H1 and H2 receptor blockers (diphenhydramine and cimetidine, respectively) reduced the intensity of capillary engorgement and edema. Intraperitoneal injections of 48/80 (0.5 mg) was lethal to rats, and both diphenhydramine and cimetidine induced survival even with as much as 1 mg of 48/80. Intratubular fluorescence was less severe than that observed for similarly treated guinea pigs or from cadmium chloride-treated rat testes. Neither treatment (48/80 or cadmium chloride) altered the blood-epididymal barrier of either guinea pigs or rats. Species differences were observed in the lethal effects of exogenously administered histamine.

Acriflavine↗
PubMed1985

Histamine and secondary autoimmune infertility in dark mink (Mustela vison).

Testicular histamine content was higher in December (the time of sexual quiescence) that in March (breeding time) in opaline mink. Although testicular histamine synthesis increased in March over December, the increased cellular mass and increased histaminase activity prevented the biogenic amine from rising. Dark mink, however, had higher gonadal levels of histamine in March than in December owing to an increased rate of synthesis and a decreased rate of inactivation that correlated well with the onset of autoimmune infertility in this strain. Pastel mink were intermediate to the opalines, and dark mink indicative of strain differences in the genetic control of gonadal histamine synthesis and inactivation.

Amine Oxidase (Copper-Containing)↗
PubMed1985

Reduced progesterone and altered cotyledonary prostaglandin values induced by locoweed (Astragalus lentiginosus) in sheep.

Feeding 300 or 400 g of dried spotted locoweed, Astragalus lentiginosus per day to 11 pregnant Columbia ewes from the 20th to the 50th days of their gestations resulted in dead and edematous fetuses. Aspartate aminotransferase values were increased, whereas serum progesterone values were significantly diminished (P less than 0.05) in a dose-dependent manner by locoweed ingestion. Cotyledonary 6-keto-prostaglandin (PG)F1 alpha (400 g/day only) and PGF2 alpha (300 and 400 g/day) values were significantly increased (P less than 0.05), whereas PGE values were not affected by the treatment. Alterations in PG values in these sheep may be a mechanism for altering corpus luteum function and inducing fetal death, which would ultimately result in abortion.

6-Ketoprostaglandin F1 alpha↗