Placentation and hormonal maintenance of pregnancy in the impala (Aepyceros melampus).

INTRODUCTION: The impala is a widely distributed African ungulate. Detailed studies of the placenta and ovaries in impala undertaken in the 1970s did not address the endocrine functions of the placenta. METHODS: The uteri of 25 pregnant impala estimated to be between 49 and 113 days of the 190 day gestation were examined grossly, histologically and immunohistochemically. RESULTS: A single corpus luteum was present in either maternal ovary but the conceptus was always situated in the right uterine horn. The fetal membranes extended to the tips of both uterine horns. The amnion was in intimate contact with, but not fused to, the allantochorion. Placentation was typically ruminant with fetal macrocotyledons attached to the rows of maternal caruncles. The fetal villi were highly branched, especially in the centre of each placentome where the attenuated maternal epithelium lining the placental crypts was absent in some places. Both the corpus luteum and the uninucleate trophoblast cells of the interplacentomal allantochorion stained strongly for 3-ß hydroxysteroid dehydrogenase, and progestagen concentrations in allantoic and amniotic fluids increased significantly as gestation progressed, with a tendency to do likewise in maternal serum. Binucleate trophoblast cells stained positively for bovine placental lactogen, but neither the placenta nor the maternal corpus luteum showed evidence of oestrogen synthesis. DISCUSSION: Despite exhibiting the same basic type of placentation, both the gross and histological structure of the impala placenta, along with its immunohistochemical properties, demonstrates that great variation exists across ruminant placentas.

Relationships between clinical measures of visual function, fluorescein angiographic and optical coherence tomography features in patients with subfoveal choroidal neovascularisation.

AIMS: To examine the relationships between measures of vision, optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) characteristics in patients with exudative age-related macular degeneration (AMD). STUDY DESIGN: Retrospective case note review. Inclusion criteria were: confirmed diagnosis of new exudative AMD; recorded visual function using best corrected distance visual acuity (DVA), near visual acuity (NVA) and contrast sensitivity; corresponding FFA and OCT. FFA parameters included greatest linear diameter of lesion (GLD), area of choroidal neovascularisation (CNV) and area of leakage. OCT parameters included maximum retinal thickness (Ret(max)), central foveal thickness, maximum thickness of the CNV (CNV(max)), and the distances from the foveal depression to Ret(max) and CNV(max). RESULTS: 74 patients were included in this study. Correlations were highly statistically significant for both NVA and contrast sensitivity with GLD, CNV area and leakage (p<0.01 for all combinations). With DVA, modest statistically significant correlations were seen with CNV area and GLD (p<0.05). There was a statistically significant correlation between CNV leakage and the distance of CNV(max) to the fovea (p<0.05). The relationships between the measures of vision and OCT parameters were weak and did not reach significance. Regression analysis showed that the combination of Ret(max), GLD, and CNV(max) to fovea had the highest coefficient (r2 = 0.27). CONCLUSION: OCT measurements by themselves are not robust markers for visual function.

The RhoGEF domain of p210 Bcr-Abl activates RhoA and is required for transformation.

The BCR-ABL oncogene encodes an in-frame fusion protein containing N-terminal sequences derived from Bcr and C-terminal sequences derived from Abl. Bcr contains a centrally located Rho-specific guanine nucleotide exchange factor (RhoGEF) domain that is retained within p210 Bcr-Abl. Although this domain is subject to autoinhibition in the context of Bcr, here we show that it is constitutively activated in p210 Bcr-Abl. p210 Bcr-Abl can stimulate RhoA activation independently of its tyrosine kinase activity, and mutations within the RhoGEF domain that are predicted to eliminate RhoGEF activity inhibit RhoA activation. The RhoGEF mutant of p210 Bcr-Abl does not affect the tyrosine kinase activity of the molecule, nor the ability of p210 Bcr-Abl to interact with XPB through the RhoGEF domain. Despite retaining normal levels of tyrosine kinase activity, the RhoGEF mutant of p210 Bcr-Abl is impaired in transforming activity as measured by anchorage-independent growth. However, the mutant is still able to confer the phenotype of growth factor independence in myeloid cells, suggesting that some, but not all parameters of p210 Bcr-Abl transformation, are dependent upon a catalytically active RhoGEF domain. Collectively, these observations identify a gain-of-function activity attributable to the RhoGEF domain of p210 Bcr-Abl that is required to support the transformed phenotype.

Emergency department protocolised management of acute atrial fibrillation: how many patients in a tertiary hospital are eligible?

An emergency observation department unit (EDOU) treatment protocol for the management of acute atrial fibrillation (AAF) has been demonstrated to be feasible in the United States of America. The aim of this study was to quantify the number of patients presenting with AAF eligible for EDOU protocolized management in an Irish hospital. A retrospective observational study was performed by identifying a sample of patients admitted to hospital with acute atrial fibrillation between January and December 2002. Medical records of one hundred and eleven patients presenting with AAF were identified. Nine patients were eligible for EDOU management. Fourteen patients (12.6%) reverted spontaneously to sinus rhythm in the ED without medical intervention. Eight percent of patients presenting with AAF in an Irish hospital are eligible for protocolized EDOU management.

Chloroquine causes lysosomal dysfunction in neural retina and RPE: implications for retinopathy.

Chronic use of chloroquine has been shown to induce numerous pathophysiological defects in the retina. This drug has the ability to alter pH of intracellular compartments and lysosomal function of the retinal pigment epithelium (RPE) and retinal neurons may constitute the basis of chloroquine retinopathy. The aim of the current study was to investigate pathogenic alterations in retinal cells continuously exposed to chloroquine using appropriate in vivo and in vitro models. Male hooded Lister rats were implanted with osmotic mini pumps which released chloroquine continuously over a period of seven days. The eyes were processed for electron microscopy and ultrastructural abnormalities determined in the neural retina and quantified using stereology in the retinal pigment epithelium (RPE). RPE were also exposed to chloroquine in vitro and lysosomal pH changes were investigated using a pH sensitive probe. Degradative capacity was also analysed using FITC labeled rod outer segments (ROS). Chloroquine-treated animals displayed several ultrastructural abnormalities including numerous membranous cytoplasmic bodies (MCBs) in retinal neurons. Cone photoreceptors displayed numerous MCBs although rods did not. The RPE of the treated groups all showed significantly higher numbers of lysosomal associated organelles (LAO) than the control group (p < 0.001). The in vitro experiments demonstrated chloroquine-mediated rises in lysosomal pH and an increase in lysosome/phagosome accumulation of ROS in the chloroquine treated group (p < 0.01). The current study demonstrates that chloroquine disrupts lysosomal function in retinal neurons and RPE. The evidence presented provides a clear pathogenic basis for the functional defects experienced by patients with chloroquine retinopathy.

The corneal epithelial stem cell.

The aim of this paper was to develop a GFP-expressing transgenic mouse model for the keratoepithelioplasty and to use this to follow the outcome of this form of graft, when placed on an inflamed corneal surface. Further aims were to characterize both the graft and the epithelial surface of the mouse and rat cornea using putative stem cell markers (P63 and Telomerase) and marker of cell differentiation (14-3-3 sigma). Keratepithelioplasty was carried out using a GFP transgenic mouse cornea as donor tissue. Fluorescent epithelial outgrowth from each keratepithelioplasty was scored and quantified. Donor corneal graft tissue was obtained from the paracentral region or the anatomical limbal region of murine corneas. Paracentral donor grafts (n = 20) consistently demonstrated a significant increase in proliferative potential compared to grafts obtained from the anatomical limbal region of the mouse cornea (n = 25) (P = 0.000, Mann-Whitney U). Correspondingly, P63 expression was maximal in the paracentral region of the mouse cornea, in keeping with the demonstrated increased proliferative potential of donor grafts harvested from this region of the cornea. The murine corneal epithelium demonstrated decreased rather than increased cellular layers at the limbal region, in contrast to that of the rat or human epithelium. In addition, as a general finding in all species tested, there was an apparent increase noted in P63 expression in basal corneal epithelial cells in regions that had increased cellular layers (limbus in humans and rats and the paracentral corneal region in the mouse). Epithelium, which had migrated from donor grafts onto recipient corneas, retained P63 expression for the period of time examined (up to 3 days postengraftment). In addition, the conjunctival surface of an injured conjunctivalized displayed an abnormal pattern of P63 expression. Telomerase expression was widespread throughout many layers of both the murine and rat corneal epithelium. In the mouse and rat corneal epithelium P63 expression was maximal in areas of increased proliferative potential. Its expression, however, was not confined to stem cells alone. Migrating cells from transplanted keratoepithelial grafts retained P63 expression at least in the early stages post-transplantation. Finally, damaged conjunctivalized corneas displayed an abnormal P63 expression pattern when compared to either normal conjunctiva or normal cornea.

The thrombin receptor, PAR-1, causes transformation by activation of Rho-mediated signaling pathways.

We utilized a cDNA expression library derived from the B6SutA(1) mouse myeloid progenitor cell line to search for novel oncogenes that promote growth transformation of NIH3T3 cells. A 2.2 kb transforming cDNA was recovered that encodes the wild type thrombin-stimulated G protein-coupled receptor PAR-1. In addition to its potent focus forming activity, constitutive overexpression of PAR-1 in NIH3T3 cells promoted the loss of anchorage- and serum-dependent growth. Although inhibitors of thrombin failed to block PAR-1 transforming activity, a PAR-1 mutant that cannot be cleaved by thrombin was nontransforming. Since the foci of transformed cells induced by PAR-1 bear a striking resemblance to those induced by activated RhoA, we determined if PAR-1 transformation was due to the aberrant activation of a specific Rho family member. Like RhoA, PAR-1 cooperated with activated Raf-1 and caused synergistic enhancement of transforming activity, induced stress fibers when microinjected into porcine aortic endothelial cells, stimulated the activity of the serum response factor and NF-kappaB transcription factors, and PAR-1 transformation was blocked by co-expression of dominant negative RhoA. Finally, PAR-1 transforming activity was blocked by pertussis toxin and by co-expression of the RGS domain of Lsc, implicating Galpha(i) and Galpha(12)/Galpha(13) subunits, respectively, as mediators of PAR-1 transformation. Taken together, these observations suggest that PAR-1 growth transformation is mediated, in part, by activation of RhoA.

Silicone oil-intraocular lens interaction: which lens to use?

AIM: To determine a suitable intraocular lens for implantation in patients at high risk of lens exposure to silicone oil in their lifetime. METHODS: PMMA, AcrySof, AR40, AQUA-Sense, and Raysoft lenses were examined. Each lens was immersed for 5 minute intervals in balanced salt solution (BSS), in stained silicone oil, and again in BSS before being photographed in air and in BSS. Percentage silicone oil coverage of the lens optic was determined. RESULTS: The mean percentage coating (MPC) for the lens biomaterials ranged from 5.2% to 21.5%. The Raysoft lens had significantly less oil coverage when statistically compared with the other lens types (p < 0.001). CONCLUSION: A Raysoft (Rayner) lens is a suitable lens for implantation in patients who are at risk of severe vitreoretinal disease.

Dependence of Dbl and Dbs transformation on MEK and NF-kappaB activation.

Dbs was identified initially as a transforming protein and is a member of the Dbl family of proteins (>20 mammalian members). Here we show that Dbs, like its rat homolog Ost and the closely related Dbl, exhibited guanine nucleotide exchange activity for the Rho family members RhoA and Cdc42, but not Rac1, in vitro. Dbs transforming activity was blocked by specific inhibitors of RhoA and Cdc42 function, demonstrating the importance of these small GTPases in Dbs-mediated growth deregulation. Although Dbs transformation was dependent upon the structural integrity of its pleckstrin homology (PH) domain, replacement of the PH domain with a membrane localization signal restored transforming activity. Thus, the PH domain of Dbs (but not Dbl) may be important in modulating association with the plasma membrane, where its GTPase substrates reside. Both Dbs and Dbl activate multiple signaling pathways that include activation of the Elk-1, Jun, and NF-kappaB transcription factors and stimulation of transcription from the cyclin D1 promoter. We found that Elk-1 and NF-kappaB, but not Jun, activation was necessary for Dbl and Dbs transformation. Finally, we have observed that Dbl and Dbs regulated transcription from the cyclin D1 promoter in a NF-kappaB-dependent manner. Previous studies have dissociated actin cytoskeletal activity from the transforming potential of RhoA and Cdc42. These observations, when taken together with those of the present study, suggest that altered gene expression, and not actin reorganization, is the critical mediator of Dbl and Rho family protein transformation.

Recognition of class I major histocompatibility complex molecules by Ly-49: specificities and domain interactions.

Ly-49 is a family type II transmembrane proteins encoded by a gene cluster on murine chromosome 6. One member of this family, Ly-49A, is expressed by a natural killer (NK) cell subset, binds to class I major histocompatibility complex (MHC) molecules, and blocks the killing of target cells bearing the appropriate H-2 antigens. Here we show that another member of this family which is expressed by an NK cell subset, Ly-49C, recognizes H-2b and H-2d structures which are distinct from and overlapping with those recognized by Ly-49A. Interactions between Ly-49A and C and their class I ligands are entirely blocked by the antibodies 5E6, YE1/48, YE1/32, and A1, all of which were found to recognize epitopes contained within the carbohydrate recognition domain (CRD). However, cell-cell binding assays revealed that class I binding specificity is conferred by a combination of sequences within both the CRD and a 19-amino acid adjacent region. We also investigated the question of whether Ly-49A and C form dimers on cells which express both receptors. When coexpressed on COS cells, sequential immunoprecipitation demonstrated that these receptors pair exclusively as homodimers, with no evidence for heterodimeric structures. These observations provide insight into both the biochemical nature of the Ly-49 family as well as the receptor functions of Ly-49C on NK cells.

Alcoholism and prescription drug abuse in the elderly: St. Louis University grand rounds.

This Grand Rounds will review the problem of alcoholism and prescription drug abuse in the elderly. Several case vignettes will be presented. The pharmacology of alcohol and potentially addictive prescription medications will be reviewed. The clinical presentation of and psychiatric symptoms associated with these disorders will be discussed. The process of addiction and issues regarding the clinical evaluation of the elderly addict will be discussed. The medical complications of these disorders will be reviewed, followed by a discussion of guidelines for the appropriate use of these drugs in the elderly. The grand rounds will conclude with a discussion of the treatment of patients with these disorders.

Ocular siderosis.

The authors report their experience in the management of 8 patients with ocular siderosis due to a retained intraocular foreign body (IOFB). All patients were male, aged between 19 and 39 years. Seven had a definite history of trauma; 3 had presented at the time of injury to a casualty department, and the diagnosis had been missed. The interval between injury and diagnosis ranged from 2 to 24 months. IOFB removal was performed in 7 patients: through a sclerotomy and magnet or foreign body forceps in 4 eyes and via a pars plana vitrectomy and intraocular foreign body forceps in 3 eyes. Cataract extraction was performed in 4 patients. Histological examination of specimens removed at the time of surgery showed iron deposition in the conjunctiva, anterior lens capsule and pars plana. Transmission electron microscope X-ray microanalysis showed that iron was contained in siderosomes, intracytoplasmic membrane-bound dense bodies. Final visual acuity was 6/12 or better in 6 patients and reduced to light perception in the remaining 2 due to proliferative vitreoretinopathy.

Ultrastructural findings in solar retinopathy.

This study documents the ultrastructural findings in a case of solar retinopathy, 6 days after sungazing. A malignant melanoma of the choroid was diagnosed in a 65-year-old man. On fundoscopy, the macula was normal. The patient agreed to stare at the sun prior to enucleation. A typical solar retinopathy developed, characterised by a small, reddish, sharply circumscribed depression in the foveal area. Structural examination of the fovea and parafovea revealed a spectrum of cone and rod outer segment changes including vesiculation and fragmentation of the photoreceptor lamellae and the presence of discrete 100-120 nm whorls within the disc membranes. Many photoreceptor cells, particularly the parafoveal rods, also demonstrated mitochondrial swelling and nuclear pyknosis. Scattered retinal pigment epithelial cells in the fovea and parafovea showed a degeneration characterised by loss of plasma membrane specialisations, swelling of the smooth endoplasmic reticulum and changes in the fine structure of the lipofuscin granules. The good visual prognosis in solar retinopathy was attributed to the resistance of the foveal cone cells to photochemical damage.

Late ultrastructural changes in the retina of the rat following low-dose X-irradiation.

This study describes ultrastructural changes in the pigmented hooded Lister rat retina, 3-12 months following X-irradiation with single doses of between 200 and 2000 cGy. The extreme radiosensitivity of the photoreceptor cells was underlined by the continued manifestation of fine structural changes and cell death up to 6 months post-radiation in animals receiving doses above 500 cGy. The retinal pigment epithelial (RPE) cells were more radioresistant than photoreceptors and RPE cell loss was only observed at doses of more than 1500 cGy. One year after irradiation with 1500 cGy the retinal vasculature showed capillary occlusion with some evidence of recanalisation. Telangiectasia was observed in the large retinal veins. Although the inner retinal neurones and glial cells showed no evidence of direct radiation damage, the nerve fibre layer adjacent to occluded retinal vessels demonstrated ultrastructural evidence of ischaemic neuropathy and retinal oedema. At doses above 1500 cGy the choriocapillaris showed platelet aggregation and capillary loss.

Early ultrastructural changes after low-dose X-irradiation in the retina of the rat.

In this study Lister rats were given doses of X-rays ranging from 200-2,000 Rads to the retina of one eye, sacrificed at various time intervals between one hour and one month later and the irradiated eye processed for electron microscopy. The rod photoreceptor cells were by far the most radiosensitive cells in the retina, their outer segments showing distinctive membrane damage at one hour after 200 Rads of X-rays. Photoreceptor cell death was not seen at doses less than 1,000 Rads in the time period of the experiment. The retinal pigment epithelial (RPE) cells showed damage in the form of mitochondrial swelling but only in doses over 500 Rads. Retinal pigment epithelial cell loss did not occur under 2,000 Rads. The inner retinal neurones, glial elements and the retinal vasculature did not show any ill effects in the time period of this study.