Retinal and lenticular ultrastructure in the aestivating salamanderfish, Lepidogalaxias salamandroides (Galaxiidae, Teleostei) with special reference to a new type of photoreceptor mosaic

The salamanderfish, Lepidogalaxias salamandroides (Galaxiidae, Teleostei) is endemic to southwestern Australia and inhabits shallow, freshwater pools which evaporate during the hot summer months. Burrowing into the substrate in response to falling water levels allows these fish to aestivate for extended periods of time while encapsulated in a mucous cocoon even when the pools contain no water. Only a few minutes after a major rainfall, these fish emerge into relatively clear water which subsequently becomes laden with tannin, turning the water black and reducing the pH to approximately 4.3. As part of a large study of the visual adaptations of this unique species, the retinal and lenticular morphology of the aestivating salamanderfish is examined at the level of the light and electron microscopes. The inner retina is highly vascularised by a complex system of vitreal blood vessels, while the outer retina receives a blood supply by diffusion from a choriocapillaris. This increased retinal blood supply may be an adaptation for reducing the oxygen tension during critical periods of aestivation. Large numbers of Muller cells traverse the thickness of the retina from the inner to the outer limiting membranes. The ganglion cells are arranged in two ill-defined layers, separated from a thick inner nuclear layer containing two layers of horizontal cells by a soma-free inner plexiform layer. The photoreceptors can be divided into three types typical of many early actinopterygian representatives; equal double cones, small single cones and large rods (2:1:1). These photoreceptors are arranged into a unique regular square mosaic comprising a large rod bordered by four equal double cones with a small single cone located at the corner of each repeating unit. The double cones may optimise perception of mobile prey which it tracks by flexion of its head and neck and the large rods may increase sensitivity in the dark tannin-rich waters in which it lives. Each single cone also possesses a dense collection of polysomes and glycogen (a paraboloid) beneath its ellipsoid, the first such finding in teleosts. The retinal pigment epithelium possesses melanosomes, pha,oocytes and a large number of mitochondria. The anatomy of the retina and the photoreceptor mosaic is discussed in relation to the primitive phylogeny of this species and its unique life history.

Hypoxia stimulates cerebral blood flow in the estuarine crocodile (Crocodylus porosus)

The effect of N-2 respiration on cerebral blood flow (CBF) velocity on the dorsal surface of cerebellum was examined in the estuarine crocodile, Crocodylus porosus, using epi-illumination microscopy. Twelve minutes of N-2 respiration resulted in a 126% increase in CBF velocity. N-2 respiration had no effect on blood pressure, indicating an underlying cerebral vasodilation. In addition, heart rate increased significantly. Systemic injections of aminophylline and the NO synthase (NOS) inhibitor nitro-L-arginine (L-NA) did not affect the hypoxia induced increase in CBF. We conclude that C. porosus responds to hypoxia with adenosine and nitric oxide (NO) independent cerebral vasodilation, and that this is likely to be a mechanism protecting the brain from energy deficiency during prolonged dives. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

Targeting local tissues by transdermal application: Understanding drug physicochemical properties that best exploit protein binding and blood flow effects

The targeting of topically applied drug molecules into tissues below a site of application requires an understanding of the complex interrelationships between the drug, its formulation, the barrier properties of the skin, and the physiological processes occurring below the skin that are responsible for drug clearance from the site, tissue, and/or systemic distribution and eventual elimination. There is still a certain amount of controversy over the ability of topically applied drugs to penetrate into deeper tissues by diffusion or whether this occurs by redistribution in the systemic circulation. The major focus of our work in this area has been in determining how changes in drug structure and physicochemical properties, such as protein binding and lipophilicity, affect drug clearance into the local dermal microcirculation and lymphatics, as well as subsequent distribution into deeper tissues below an application site. The present study outlines our recent thinking on the drug molecule optimal physical attributes, in terms of plasma and tissue partitioning behaviour, that offer the greatest potential for deep tissue targeting. Drug Dev. Res. 46:309-315, 1999. (C) 1999 Wiley-Liss, Inc.

Binding of YY1 and Oct1 to a novel element that downregulates expression of IL-5 in human T cells

Background: IL-5 controls development of eosinophilia and has been shown to be involved in the pathogenesis of allergic diseases. In both atopic and nonatopic asthma, elevated IL-5 has been detected in peripheral blood and the airways. IL-5 is produced mainly by activated T cells, and its expression is regulated at the transcriptional level. Objective: This study focuses on the functional analysis of the human IL-5 (hIL-5) promoter and characterization of eis-regulatory elements and transcription factors involved in the suppression of IL-5 transcription in T cells. Methods: Methods used in this study include DNase I footprint assays, electrophoretic mobility shift assays, and functional analysis by mammalian cell transfection involving deletion analysis and site-directed mutagenesis. Results: We identified 5 protein binding regions (BRs) located within the proximal hIL-5 promoter. Functional analysis indicates that the BRs are involved in control of hIL-5 promoter activity. Two of these regions, BR3 and BR4 located at positions -102 to -73, have not previously been described as regulators of IL-5 expression in T cells. We show that the BR3 sequence contains a novel negative regulatory element located at positions -90 to -79 of the hIL-5 promoter, which binds Oct1, octamer-like, and YY1 nuclear factors. Substitution mutations, which abolished binding of these proteins to the BR3 sequence, significantly increased hIL-5 promoter activity in activated T cells. Conclusion: We suggest that Oct1, YY1, and octamer-like factors binding to the -90/-79 sequence within the proximal IL-5 promoter are involved in suppression of IL-5 transcription in T cells.

A rapid selection/amplification procedure for high-level expression of recombinant protein in a metal-amplifiable mammalian expression system

We describe a strategy for the selection and amplification of foreign gene expression in Chinese hamster ovary (CHO) cells employing a metallothionein gene-containing expression vector. This report describes an amplification procedure that results in an enrichment of clones exhibiting high levels of recombinant protein production and reduces the labour required for screening recombinant cell lines.

Gene transfer and expression of a non-viral polycation-based vector in CD4(+) cells

CD4-selective targeting of an antibody-polycation-DNA complex was investigated The complex was synthesized with the anti-CD4 monoclonal antibody B-F5, polylysine(268) (pLL) and either the pGL3 control vector containing the luciferase reporter gene or the pGeneGrip vector containing the green fluorescent protein (GFP) gene. B-F5-pLL-DNA complexes inhibited the binding of I-125-B-F5 to CD4(+) Jurkat cells, while complexes synthesised either without B-F5 or using a non-specific mouse IgG1 antibody had little or no effect Expression of the luciferase reporter gene was achieved in Jurkat cells using the B-F5-pLL-pGL3 complex and was enhanced in the presence of PMA. Negligible luciferase activity was defected with the non-specific antibody complex in Jurkat cells or with the B-F5-pLL-pGL3 complex in the CD4(-) K-562 cells. Using complexes synthesised with the pGeneGrip vector, the transfection efficiency in Jurkat and K-562 cells was examined using confocal microscopy. More than 95% of Jurkat cells expressed GFP and the level of this expression was markedly enhanced by PMA. Negligible GFP expression was seen in K-562 cells or when B-F5 was replaced by a nonspecific antibody. Using flow cytometry, fluorescein-labelled complex showed specific targeting to CD4(+) cells in a mixed cell population from human peripheral blood. These studies demonstrate the selective transfection of CD4(+) T-lymphoid cells using a polycation-based gene delivery system. The complex may provide a means of delivering anti-HIV gene therapies to CD4(+) cells in vivo.

Administration of growth hormone or IGF-I to pregnant rats on a reduced diet throughout pregnancy does not prevent fetal intrauterine growth retardation and elevated blood pressure in adult offspring

Increasing evidence from human epidemiological studies suggests that poor growth before birth is associated with postnatal growth retardation and the development of cardiovascular disease in adulthood. We have shown previously that nutritional deprivation in the pregnant rat leads to intrauterine growth retardation (IUGR), postnatal growth failure, changes in the endocrine parameters of the somatotrophic axis, and to increased blood pressure in later life. In the present study, we investigated whether administration of insulin-like growth factor-I (IGF-I) or bovine growth hormone (GH) during pregnancy could prevent IUGR and/or alter long-term outcome. Dams h-om day 1 of pregnancy throughout gestation received a diet of nd libitum available food or a restricted dietary intake of 30% of ad libitum fed dams. From day 10 of gestation, dams were treated for 10 days with three times daily subcutaneous injections of saline (100 mu l), IGF-I (2 mu g/g body weight) or GH (2 mu g/g body weight). Maternal weight gain was significantly increased (P

High level of aspartic acid-bond isomerization during the synthesis of an N-linked tau glycopeptide

An increased degree of utilization of the potential N-glycosylation site In the fourth repeat unit of the human tau protein may be involved in the inability of tau to bind to the corresponding tubulin sequence(s) and in the subsequent development of the paired helical filaments of Alzheimer's disease. To model these processes, we synthesized the octadecapeptide spanning this region without sugar, and with the addition of an N-acetyl-glucosamine moiety. The carbohydrate-protected, glycosylated asparagine was incorporated as a building block during conventional Fmoc-solid phase peptide synthesis. While the crude non-glycosylated analog was obtained as a single peptide, two peptides with, the identical, expected masses, in approximately equal amounts, were detected after the cleavage of the peracetylated glycopeptide. Surprisingly, the two glycopeptides switched positions on the reversed-phase high performance liquid chromatogram after removal of the sugar-protecting acetyl groups. Nuclear magnetic resonance spectroscopy and peptide sequencing identified the more hydrophobic deprotected peak as the target peptide, and the more hydrophilic deprotected peak as a peptide analog in which the aspartic acid-bond just preceding the glycosylated asparagine residue was isomerized resulting in the formation of a beta-peptide. The anomalous chromatographic behavior of the acetylated beta-isomer could be explained on the basis of the generation of an extended hydrophobic surface which is not present in any of the other three glycopeptide variants. Repetition of the syntheses, with altered conditions and reagents, revealed reproducibly high levels of aspartic acid-bond isomerization of the glycopeptide as well as lack of isomerization for the non-glycosylated parent analog. If similar increased aspartic acid-bond isomerization occurs in vivo, a protein modification well known to take place for both the amyloid deposits and the neurofibrillary tangles in Alzheimer's disease, this process may explain the aggregation of glycosylated tau into the paired helical filaments in the affected brains. Copyright (C) 1999 European Peptide Society and John Wiley & Sons, Ltd.

Response of a two-level atom to a narrow-bandwidth squeezed-vacuum excitation

Using the coupled-system approach we calculate the optical spectra of the fluorescence and transmitted fields of a two-level atom driven by a squeezed vacuum of bandwidths smaller than the natural atomic linewidth. We find that in this regime of squeezing bandwidths the spectra exhibit unique features, such as a hole burning and a three-peak structure, which do not appear for a broadband excitation. We show that the features are unique to the quantum nature of the driving squeezed vacuum field and donor appear when the atom is driven by a classically squeezed field. We find that a quantum squeezed-vacuum field produces squeezing in the emitted fluorescence field which appears only in the squeezing spectrum while there is no squeezing in the total field. We also discuss a nonresonant excitation and find that depending on the squeezing bandwidth there is a peak or a hole in the spectrum at a frequency corresponding to a three-wave-mixing process. The hole appears only for a broadband excitation and results from the strong correlations between squeezed-vacuum photons.

Level-one highest weight representations of U-q[g1(1 vertical bar 1)] and associated vertex operators

We study the level-one irreducible highest weight representations of U-q[gl(1\1)] and associated q-vertex operators. We obtain the exchange relations satisfied by these vertex operators. The characters and supercharacters associated with these irreducible representations are calculated'. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

Public health implications of new guidelines for lead in drinking water: a case study in an area with historically high water lead levels

Concern about the neurotoxicity of lead, particularly in infants and young children, has led to a revision of blood lead levels which are considered to involve an acceptable level of human exposure. Drinking water guidelines have also been reviewed in order to reduce this source of population exposure to lead. In the last 20 years, guidelines have been reduced from 100 to 50 to 10 mu g/litre. Lead in tap water used to be a major public health problem in Glasgow because of the high prevalence of houses with lead service pipes, the low pH of the public water supply and the resulting high levels of lead in water used for public consumption. Following two separate programmes of water treatment, involving the addition of lime and, a decade later, lime supplemented with orthophosphate, it is considered that maximal measures have been taken to reduce lead exposure by chemical treatment of the water supply. Any residual problem of public exposure would require large scale replacement of lead service pipes. In anticipation of the more stringent limits for lead in drinking water, we set out to measure current lead exposure From tap water in the population of Glasgow served by the Loch Katrine water supply. to compare the current situation with 12 years previously and to assess the public health implications of different limits. The study was based on mothers of young children since maternal blood lead concentrations and the domestic water that mothers use to prepare bottle feeds are the principal sources of foetal and infant lead exposure. An estimated 17% of mothers lived in households with tap water lead concentrations of 10 mu g/litre (the WHO guideline) or above in 1993 compared with 49% in 1981. Mean maternal blood lead concentrations fell by 69% in 12 years. For a given water lead concentration, maternal blood lead concentrations were 67% lower. The mean maternal blood lead concentration was 3.7 mu g/litre in the population at large, compared with 3.3 mu g/litre in households with negligible or absent tap water lead. Nevertheless, between 63% and 76% of cases of mothers with blood lead concentrations of 10 mu g/dl or above were attributable to tap water lead. The study found that maternal blood lead concentrations were well within limits currently considered safe for human health. About 15% of infants may be exposed via bottle feeds to tap water lead concentrations that exceed the WHO guideline of 10 mu g/litre. In the context of the health and social problems which affect the well-being and development of infants and children in Glasgow, however, current levels of lend exposure are considered to present a relatively minor health problem. (C) 2000 Elsevier Science Ltd. All rights reserved.

An outbreak of blood disease of banana in Irian Jaya, Indonesia

Blood disease of banana is substantiated by using the polymerase chain reaction for the first time from Irian Jaya, Indonesia.

U-q[(sl(2)over-cap vertical bar 1)] vertex operators, screen currents, and correlation functions at an arbitrary level

Bosonized q-vertex operators related to the four-dimensional evaluation modules of the quantum affine superalgebra U-q[sl((2) over cap\1)] are constructed for arbitrary level k=alpha, where alpha not equal 0,-1 is a complex parameter appearing in the four-dimensional evaluation representations. They are intertwiners among the level-alpha highest weight Fock-Wakimoto modules. Screen currents which commute with the action of U-q[sl((2) over cap/1)] up to total differences are presented. Integral formulas for N-point functions of type I and type II q-vertex operators are proposed. (C) 2000 American Institute of Physics. [S0022-2488(00)00608-3].

Level-one highest weight representation of U-q[sl((N)over-cap vertical bar 1)] and Bosonization of the multicomponent Super t-J model

We study the level-one irreducible highest weight representations of the quantum affine superalgebra U-q[sl((N) over cap\1)], and calculate their characters and supercharacters. We obtain bosonized q-vertex operators acting on the irreducible U-q[sl((N) over cap\1)] modules and derive the exchange relations satisfied by the vertex operators. We give the bosonization of the multicomponent super t-J model by using the bosonized vertex operators. (C) 2000 American Institute of Physics. [S0022- 2488(00)00508-9].