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Biomedical subjects

J Ray

Publications and source records attributed to J Ray.

At least 37 records · Page 2Linked to original sources
PubMed1998

The Scheibe cochlea deformity with macrocephaly: a case for single channel implantation.

An 11-year-old congenitally deaf child with bilateral primitive common cavity (Scheibe type) cochleosaccular dysplasia and benign familial macrocephaly was implanted with an extracochlear single channel device with an ear level speech processor. This paper describes the assessment, findings, dilemmas in decision making, surgical procedure and the favourable outcome after implanting. The relevant literature has been reviewed and our case is presented for the unusual combination of features.

Abnormalities, Multiple↗
PubMed1998

Bilateral and multicystic major salivary gland disease: a rare presentation of primary Sjögren's syndrome.

We present a case of a 15-year-old girl with bilateral parotid and sub-mandibular salivary gland enlargement as the sole presentation of primary Sjögren's syndrome. The clinical, radiological, immunological and pathological features have been discussed. The relevant literature has been reviewed. To our knowledge this is the only reported case of Sjögren's syndrome presenting as multicystic disease with bilateral major salivary gland involvement.

Adolescent↗
PubMed1998

Counterion condensation revisited.

We review some of the characteristic properties of the structure of polyelectrolyte solutions: the condensed layer of counterions that forms abruptly at a critical threshold charge density on the polymer chain; the more diffuse Debye-Hückel cloud, which is spatially distinct from the condensed layer; and the entropic release of counterions from the condensed layer as a driving force for the binding of oppositely charged ligands. We present a reminder of the basis of our current understanding in a variety of experiments, simulations, and theories; and we attempt as well to clarify some misunderstandings. We present a new analysis of a lattice model that suggests why the limiting laws for polyelectrolyte thermodynamics have proved to be accurate despite the neglect of polymer-polymer interactions in their original derivation. We sketch recent progress in constructing a potential between counterion and polyion. A counterion located in the interface between condensed layer and Debye cloud is repelled from the polyion, creating a sharp boundary between the two counterion populations.

Electrolytes↗
PubMed1998

Differential splicing of type II procollagen mRNA in canine retina.

Canine retina expressed two forms of Type II procollagen mRNA, IIA and IIB, due to alternate splicing of exon 2 at the N-propeptide region. The N-propeptide region of Type II procollagen showed a high degree of homology with human, approximately 96% both at the nucleotide and the amino acid levels. Expression of IIA and IIB forms of Type II procollagen from early stage of development to adult life suggests the important role of both forms for the development as well as maintenance of the ocular structure.

Alternative Splicing↗
PubMed1998

Retroviral cDNA transfer to the RPE: stable expression and modification of metabolism.

PURPOSE: To determine the versatility of retroviral vector-mediated rat beta-glucuronidase cDNA expression in the normal retinal pigment epithelium (RPE) of eyes of various species and in RPE of eyes with three types of mucopolysaccharidosis (MPS types I, VI, and VII) and to evaluate the effect of multiple transductions and long-term stable expression in the RPE. METHODS: A retroviral construct containing a rat beta-glucuronidase cDNA (NTK-BGEO) was used to infect RPE cells at subconfluence. The transduced cells were selected in G418, an antibiotic toxic to normal mammalian cells. Beta-glucuronidase activity was measured in transduced cells and media, using a fluorogenic substrate. Glycosaminoglycan profiles were examined by metabolically labeling RPE with Na2(35)SO4. RESULTS: Transduced RPE cells, regardless of species or disease status, expressed rat beta-glucuronidase. The expressed enzyme restored normal levels of glycosaminoglycans in the RPE cells of homozygous MPS VII-affected dogs by metabolizing stored glycosaminoglycans. The expressed enzyme failed to metabolize stored glycosaminoglycans of MPS I and MPS VI, indicating that overexpression could not bypass the exoglycosidase restriction. Multiple transductions increased beta-glucuronidase activity several times in the cell layer and in the media. The expression was stable in vitro for at least 12 weeks. CONCLUSIONS: A retroviral vector can mediate transfer of beta-glucuronidase in various species of normal and MPS-affected RPE. The expression is stable in vitro. The metabolism of stored glycosaminoglycans in MPS needs replacement of only the deficient enzyme to reverse the storage.

Animals↗
PubMed1998

Molecular diagnostic tests for ascertainment of genotype at the mucopolysaccharidosis type VII locus in dogs.

OBJECTIVE: To develop a molecular diagnostic test to ascertain genotype of the mucopolysaccharidosis type VII (MPS VII) locus. SAMPLE POPULATION: Blood samples from 45 mixed-breed (German Shepherd Dog X Beagle) dogs that were phenotypically normal or affected with MPSVII. PROCEDURE: The canine beta-glucuronidase gene (exon 3) was amplified by polymerase chain reaction (PCR), using 2 pairs of primers to determine the genotype of the MPSVII locus by 2 independent methods. For the first method, PCR products were used for heteroduplex analysis, using conformation-sensitive gel electrophoresis. In the second method, an allele-specific restriction site was created by use of a mismatch primer in PCR. The amplified DNA fragment was digested with a restriction enzyme (Eag I) to enable identification of the wild-type and mutant alleles. RESULTS: Conformation-sensitive gel electrophoresis resulted in a single DNA band representing homoduplex when the sample contained a wild-type or MPS VII allele, but 2 bands representing hetero- and homoduplexes when both alleles were in the sample. Restriction digestion of the DNA fragment obtained by use of a mismatch primer was cleaved only when the template was a wild-type allele. Thus, samples from phenotypically normal carrier dogs that contained wild-type and MPS VII alleles were partially digested by the enzyme. CONCLUSIONS: The diagnostic test used 2 strategies for independently ascertaining the wild-type or mutant MPS VII alleles in dogs. Thus, test results can distinguish phenotypically normal MPS VII-carrier dogs from homozygous normal dogs.

Alleles↗
PubMed1998

The antiproliferative and cell cycle effects of 5,6,7, 8-tetrahydro-N5,N10-carbonylfolic acid, an inhibitor of methylenetetrahydrofolate dehydrogenase, are potentiated by hypoxanthine.

5,6,7,8-Tetrahydro-N5,N10-carbonylfolic acid (LY354899) has been demonstrated to inhibit the dehydrogenase activity of C1-tetrahydrofolate synthase. This compound was only moderately antiproliferative toward CCRF-CEM lymphocytic leukemia cells in culture, but induced apoptosis after long incubation times. Slightly greater potency was observed in CEM cells adapted to grow in low folate media. Cell cycle alterations induced by LY354899 were unique relative to antifolates that inhibit either the purine or thymidine de novo biosynthetic pathways. Based on the observed changes in DNA content, we hypothesized that inhibition of the dehydrogenase resulted in two temporally distinct events: the first was a purineless-like effect and the second was a thymineless-like effect that resulted in apoptosis. To test this hypothesis, we combined LY354899 with the purine salvage metabolite, hypoxanthine. This combination resulted in an earlier and more dramatic apoptotic response, indicating that the thymineless effect had been potentiated. Biochemical analysis of ribo- and deoxyribonucleoside triphosphates confirmed that inhibition of the dehydrogenase activity initially resulted in decreased pools of deoxypurines and deoxypyrimidines, followed 16 hr later by an increase in deoxyadenosine triphosphate (dATP) and a further decrease in deoxythymidine triphosphate (dTTP). These studies demonstrate that the inhibition of the dehydrogenase activity of C1-tetrahydrofolate synthase may represent a viable target for the development of novel antifolates. The results are discussed in terms of deoxypurine and deoxypyrimidine biosynthesis.

Antineoplastic Agents↗
PubMed1997

Hyaluronan secretion into the synovial cavity of rabbit knees and comparison with albumin turnover.

1. Hyaluronan is not only a lubricant but also enhances the synovial lining's resistance to fluid outflow. This finding led to the proposal that hyaluronan (> 2 x 10(6) Da, approximately 210 nm radius) may escape across the synovial lining less freely than smaller solutes (e.g. albumin, 6.7 x 10(4) Da, 3.6 nm radius) or water. Here multiple washouts were used to measure intraarticular hyaluronan mass and secretion rate in rabbit knees, leading to an estimate of hyaluronan turnover time. Plasma albumin permeation into the joint cavity was also measured to enable comparison of turnover times between molecules of very disparate size. 2. Endogenous hyaluronan mass in the joint cavity, analysed by high performance liquid chromatography of joint washes, was 182 +/- 9.9 micrograms (mean +/- S.E.M; n = 21). Since hyaluronan concentration in synovial fluid averages 3.62 +/- 0.19 micrograms microliters-1, the endogenous synovial fluid volume was calculated to be 50 microliters (mass/concentration), about double the aspiratable volume. 3. The hyaluronan secretion rate over 4 h was 4.80 +/- 0.77 micrograms h-1 (n = 5). The rate was significantly higher in contralateral joints expanded by 2 ml Ringer solution (5.80 +/- 0.84 micrograms h-1, n = 5, P = 0.01, Student's paired t test), indicating a stretch/hydration sensitive secretory mechanism. The newly secreted chains ((2.05-2.48) x 10(6) Da) were not significantly different in length from the endogenous chains (2.95 x 10(6) Da). 4. Hyaluronan turnover time, calculated as mass/secretion rate, was 31.4-37.9 h. This is more than an order of magnitude longer than turnover time for intra-articular albumin. The latter, determined from the intra-articular albumin mass and plasma-to-cavity permeation rate was 1.8 h (95% confidence intervals 1.2-3.5 h, n = 9). The big difference in turnover times support the view that, relative to albumin and water, hyaluronan is partially sieved out and retained in the joint cavity by the synovial lining. The lining cell layer is discontinuous, so it appears that interstitial matrix itself acts as a leaky size-selective molecular filter.

Animals↗
PubMed1997

A 10-amino acid sequence of fibroblast growth factor 2 is sufficient for its mitogenic activity on neural progenitor cells.

During development of the central nervous system, neurons and glia are generated from immature neural progenitor cells (NPCs). Basic fibroblast growth factor (FGF-2) is a mitogen for these cells both in vitro and in vivo. However, it is not known whether other members of the FGF family have similar mitogenic effects on NPCs. We have found that FGF-4, in addition to FGF-2, is a mitogen for NPCs isolated from fetal and adult central nervous systems. Other family members have no proliferative effects on these cells. FGFs transduce signals to the cytoplasm through a family of transmembrane tyrosine kinase receptors (FGFR-1-4) or their isoforms. The high-affinity receptor binding sites are found in two regions of the FGF-2 molecule. We have examined the involvement of these sites in mitogenic signaling. Synthetic peptides corresponding to sequences in FGF-2 receptor binding sites were examined in [3H]thymidine incorporation assays for their agonist or antagonist activity. A 10-aa sequence present in the first receptor binding domain has been found to act as an antagonist, blocking the mitogenic effects of FGF-2. Chemical crosslinking studies using 125I-labeled FGF-2 showed specific reduction in binding of radiolabeled FGF-2 to its receptors present on the membranes of NPCs. The identification of this sequence will assist in the study of pathways involved in signal transduction for mitogenesis in these cells and elucidate the role of FGF-2 and FGF-4 during normal development and in the pathogenesis of disease.

Animals↗
PubMed1997

Regulation of voltage- and ligand-gated currents in rat hippocampal progenitor cells in vitro.

Growth medium and substrate regulate the proliferation and differentiation of neural progenitor cells in vitro and the expression of cell type-specific histochemical markers. An important question is whether neural progenitor cells exhibit voltage- and ligand-gated currents, features characteristic of neurons, and whether these currents are regulated differentially by growth conditions. Another issue of interest is whether passaged progenitor cells, after expansion with basic fibroblast growth factor (FGF-2), exhibit the same degree of plasticity as their primary counterparts, or whether they are more committed to a particular phenotype. In primary cultures of embryonic rat hippocampal progenitor cells, growth in proliferative conditions (FGF-2) was associated with low levels of sodium, calcium, N-methyl-D-aspartate (NMDA), and kainate currents compared with other growth conditions. After multiple passages in the continued presence of FGF-2, sodium, calcium, and NMDA, responses declined further; interestingly, kainate and gamma-aminobutyric acid (GABA) responses remained substantial. Moreover, the expression of functional channels and receptors in primary cultures of progenitor cells is up-regulated strongly by growth factors such as BDNF, and NT-3, whereas sodium and calcium currents in passaged cultures respond to such growth conditions to a lesser extent. Kainate and GABA responses were present to a significant extent in passaged cultures, independent of growth condition. We conclude that environmental cues regulate different channels and receptors in distinct ways in neural progenitor cells.

Animals↗
PubMed1997

Age-related increase in activity of specific lysosomal enzymes in the human retinal pigment epithelium.

Age related changes in the activity of lysosomal enzymes have been studied in the cultured human retinal pigment epithelium cells collected from 26-85 year old donors. Among four such enzymes studied, activities of cathepsin D and beta-glucuronidase increased with the age of the donors while no notable change in activity of arylsulfatase B and alpha-mannosidase was observed. Kinetic parameters of beta-glucuronidase was measured in retinal pigment epithelium cells isolated from donors of different ages. Similar kinetic parameters for beta-glucuronidase at different ages suggest that the observed increase in the activity of the enzyme with age is not due to post-translational modification of the enzyme. Western blot analysis provides evidence for increased synthesis of beta-glucuronidase with aging. Relative proportions of glycosaminoglycans, the natural substrates of beta-glucuronidase and arylsulfatase B, in the retinal pigment epithelium altered with the age of the donors. A significant decrease of dermatan sulfate levels with aging correlates well with the observed increase in the level of beta-glucuronidase activity.

Adult↗
PubMed1997

FGF-2 is sufficient to isolate progenitors found in the adult mammalian spinal cord.

The adult rat brain contains progenitor cells that can be induced to proliferate in vitro in response to FGF-2. In the present study we explored whether similar progenitor cells can be cultured from different levels (cervical, thoracic, lumbar, and sacral) of adult rat spinal cord and whether they give rise to neurons and glia as well as spinal cord-specific neurons (e.g., motoneurons). Cervical, thoracic, lumbar, and sacral areas of adult rat spinal cord (>3 months old) were microdissected and neural progenitors were isolated and cultured in serum-free medium containing FGF-2 (20 ng/ml) through multiple passages. Although all areas generated rapidly proliferating cells, the cultures were heterogeneous in nature and cell morphology varied within a given area as well as between areas. A percentage of cells from all areas of the spinal cord differentiate into cells displaying antigenic properties of neuronal, astroglial, and oligodendroglial lineages; however, the majority of cells from all regions expressed the immature proliferating progenitor marker vimentin. In established multipassage cultures, a few large, neuron-like cells expressed immunoreactivity for p75NGFr and did not express GFAP. These cells may be motoneurons. These results demonstrate that FGF-2 is mitogenic for progenitor cells from adult rat spinal cord that have the potential to give rise to glia and neurons including motoneurons.

Animals↗
PubMed1997

Potential effect of cytokines on transgene expression in primary fibroblasts implanted into the rat brain.

Fibroblasts genetically modified with retroviral vectors fail to demonstrate long-term transgene expression upon implantation into the body. Although the mechanisms behind this phenomenon have not been elucidated, one likely cause is the response of the host to the graft. For example, genetically modified fibroblasts grafted into the brain are surrounded by activated microglia and astrocytes. The apparent inflammatory response can last for several weeks. In addition, the center of the graft is typically infiltrated with macrophage-like cells that appear to reside continuously within the graft. This proximity of inflammatory cells to the graft suggests that these cells may somehow influence transgene expression. In the current study, an in vitro model was used to test the effect cytokines [transforming growth factor-beta1 (TGF-beta1), interleukin-1beta, (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha)] that are typically released by peripheral macrophages, activated microglia and/or astrocytes have on long-terminal repeat (LTR)-driven transgene expression in primary fibroblasts. Our data demonstrate that these cytokines can significantly reduce the steady-state level of proviral mRNA. The amount of proviral mRNA returned to control levels within 24 h if the cytokines were removed. In addition, the down-regulation of proviral mRNA levels could be prevented if the cells were incubated with dexamethasone (25 microM) concurrent with the introduction of cytokines. These data demonstrate that cytokines can down-regulate LTR-driven transgene expression in primary fibroblasts maintained in culture. This interaction may be a major reason why transduced cells do not demonstrate long-term transgene expression in vivo.

Animals↗
PubMed1997

A rare case of Salmonella neck abscess.

A case of a deep neck abscess caused by Salmonella enteritidis in a 29-year-old previously undiagnosed diabetic patient is reported. Review of relevant literature has shown 11 cases of Salmonella neck abscess. Predisposing conditions include immunosuppression due to any cause. Salmonella sp. should be included in the differential diagnosis of head and neck abscesses in predisposed individuals and treated accordingly.

Abscess↗