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Biomedical subjects

J Ray

Publications and source records attributed to J Ray.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cloning of the canine beta-glucuronidase cDNA, mutation identification in canine MPS VII, and retroviral vector-mediated correction of MPS VII cells.

Mucopolysaccharidosis type VII (MPS VII) is an inherited disease resulting from deficient activity of the lysosomal acid hydrolase beta-glucuronidase (GUSB) and has been reported in humans, mice, cats, and dogs. To characterize canine MPS VII, we have isolated and sequenced the canine GUSB cDNA from normal and affected animals. A single nucleotide substitution was detected in the GUSB cDNA derived from MPS VII dogs. This guanosine to adenine base change at nucleotide position 559 in the canine cDNA sequence causes an arginine to histidine substitution at amino acid position 166. Introduction of the G to A substitution at position 559 in a mammalian expression vector containing the normal canine GUSB cDNA nearly eliminated the GUSB enzymatic activity, demonstrating that this mutation is the cause of canine MPS VII. A retroviral vector expressing the full-length canine beta-glucuronidase cDNA corrected the deficiency in MPS VII cells.

Amino Acid Sequence↗
PubMed1998

The implementation of prompted retinal screening for diabetic eye disease by accredited optometrists in an inner-city district of North London: a quality of care study.

Diabetic retinopathy remains the most common cause of blindness in people of working age but the provision of high quality eye screening for diabetic patients is still erratic in many health districts in the UK. National consensus guidelines recommend comprehensive population coverage, high sensitivity (>80%), high specificity (>95%), agreed clinical criteria, referral procedures and centralized data collection to facilitate audit. This study looks at the effectiveness of implementing a prompted recall programme for retinal screening in an inner-city district of North London. The scheme uses trained, accredited optometrists to screen patients with diabetes who are looked after in the community by their general practitioner. During the first 17 months of the scheme, 63 optometrists attended training and gained accreditation. Of the 666 patients recruited, 645 were scheduled for screening and 536 (83%) attended. Fourteen per cent of patients screened were found to have background retinopathy and 2.3% sight-threatening eye disease. In two audits, carried out 15 months apart in a random sample of GP practices, the incidence of recorded dilated fundoscopy increased from 48% at baseline to 56%, an increase of 8% (95% CIs 2%-14%). For referable eye disease, the sensitivity of this screening technique was 100%, the specificity 94% (95% CIs 90%-98%), the positive predictive value 79% (95% CIs 72%-86%) and the negative predictive value 100%. The administrative cost per case screened was Pound Sterling 12.60 (excluding clinical costs and any additional optometry payment).

Diabetic Retinopathy↗
PubMed1998

Multipotent progenitor cells in the adult dentate gyrus.

Neurogenesis persists in the adult dentate gyrus of rodents throughout the life of the organism. The factors regulating proliferation, survival, migration, and differentiation of neuronal progenitors are now being elucidated. Cells from the adult hippocampus can be propagated, cloned in vitro, and induced to differentiate into neurons and glial cells. Cells cultured from the adult rodent hippocampus can be genetically marked and transplanted back to the adult brain, where they survive and differentiate into mature neurons and glial cells. Although multipotent stem cells exist in the adult rodent dentate gyrus, their biological significance remains elusive.

Animals↗
PubMed1998

Cochlear implant failure due to unexpected absence of the eighth nerve--a cautionary tale.

We present a case of bilateral absence of the eighth cranial nerve in the internal auditory meatus (IAM). This caused total failure of responses after cochlear implantation in a six-year-old patient with congenital deafness. Pre-operative magnetic resonance (MR) imaging is important to show not only the anatomy of the middle and inner ears but also the structures in the IAM.

Child↗
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↗