Biomedical subjects

C Ferguson

Publications and source records attributed to C Ferguson.

At least 19 recordsLinked to original sources

PubMed2001

GABA(A) receptor alpha1 subunit deletion prevents developmental changes of inhibitory synaptic currents in cerebellar neurons.

Developmental changes in miniature IPSC (mIPSC) kinetics have been demonstrated previously in cerebellar neurons in rodents. We report that these kinetic changes in mice are determined primarily by developmental changes in GABA(A) receptor subunit expression. mIPSCs were studied by whole-cell recordings in cerebellar slices, prepared from postnatal day 11 (P11) and P35 mice. Similar to reports in granule neurons, wild-type cerebellar stellate neuron mIPSCs at P11 had slow decay kinetics, whereas P35 mIPSCs decayed five times faster. When mIPSCs in cerebellar stellate neurons were compared between wild-type (+/+) and GABA(A) receptor alpha1 subunit-deficient (-/-) littermates at P35, we observed dramatically slower mIPSC decay rates in -/- animals. We took advantage of the greater potency of imidazopyridines for GABA current potentiation with alpha1 subunit-containing receptors to characterize the relative contribution of alpha1 subunits in native receptors on inhibitory synapses of cerebellar granule neurons. Zolpidem-induced prolongation of mIPSC decay was variable among distinct cells, but it increased during development in wild-type mice. Similarly, Zolpidem prolongation of mIPSC decay rate was significantly greater in adult +/+ mice than in knock-outs. We propose that an increased alpha1 subunit assembly in postsynaptic receptors of cerebellar inhibitory synapses is responsible for the fast inhibitory synaptic currents that are normally observed during postnatal development.

Animals↗

PubMed2001

Prostate short-chain dehydrogenase reductase 1 (PSDR1): a new member of the short-chain steroid dehydrogenase/reductase family highly expressed in normal and neoplastic prostate epithelium.

Genes regulated by androgenic hormones are of critical importance for the normal physiological function of the human prostate gland, and they contribute to the development and progression of prostate carcinoma. We used cDNA microarrays comprised of prostate-derived cDNAs to profile transcripts regulated by androgens in prostate cancer cells. This study identified a novel gene that we have designated prostate short-chain dehydrogenase/reductase 1 (PSDR1), that exhibits increased expression on exposure to androgens in the LNCaP prostate cancer cell line. Northern analysis demonstrated that PSDR1 is highly expressed in the prostate gland relative to other normal human tissues. The PSDR1 cDNA and putative protein exhibit homology to the family of short-chain dehydrogenase/reductase enzymes and thus identify a new member of this family. Cloning and analysis of the putative PSDR1 promoter region identified a potential androgen-response element. We used a radiation-hybrid panel to map the PSDR1 gene to chromosome 14q23-24.3. In situ hybridization localizes PSDR1 expression to normal and neoplastic prostate epithelium. These results identify a new gene involved in the androgen receptor-regulated gene network of the human prostate that may play a role in the pathogenesis of prostate carcinoma.

Amino Acid Sequence↗

PubMed2001

GABA influences the development of the ventromedial nucleus of the hypothalamus.

The region that becomes the ventromedial nucleus of the hypothalamus (VMH) is surrounded by cells and fibers containing immunoreactive gamma-aminobutyric acid (GABA) by embryonic day 13 (E13), several days before the nucleus emerges in Nissl stains. As GABA plays many roles during neural development, we hypothesized that it influences VMH development, perhaps by providing boundary information for migrating neurons. To test this hypothesis we examined the VMH in embryonic mice in which the beta3 subunit of the GABA(A)-receptor, a receptor subunit that is normally highly expressed in this nucleus, was disrupted by gene targeting. In beta3 -/- embryos the VMH was significantly larger, and the distribution of cells containing immunoreactive estrogen receptor-alpha was expanded compared to controls. Using in vitro brain slices from wild-type C57BL/6J mice killed at E15 we found that treatment with the GABA(A) antagonist bicuculline increased the number of cells migrating per video field analyzed in the VMH. In addition, treatment with either bicuculline or the GABA(A) agonist muscimol altered the orientation of cell migration in particular regions of this nucleus. These data suggest that GABA is important for the organization of cells during VMH formation.

Animals↗

PubMed2001

Intraspecific differences in behaviour and physiology: effects of captive breeding on patterns of torpor in feathertail gliders.

Studies on the physiology of mammals and birds are often conducted using captive-bred individuals and it is commonly assumed that the resulting data are representative of individuals living in the field. To investigate whether these assumptions are justified, we quantified morphological, behavioural, and physiological variables of the small marsupial feathertail glider (Acrobates pygmaeus). We compared three populations: (i) individuals from a cool-temperate, montane area, (ii) individuals form a subtropical, coastal area, and (iii) captive-bred individuals. Captive-bred gliders differed from the montane field gliders in morphology (longer tails and snouts), behaviour (longer activity periods) and physiology (less frequent torpor, shorter torpor, shallower torpor, higher metabolic rates during rest and torpor, and slower rates of rewarming). Most of these differences were also apparent between the captive-bred and the coastal field gliders. Unlike both field populations, captive-bred gliders often became hypothermic and were unable to rewarm. In contrast to the other physiological variables, the minimum body temperatures defended during torpor and the corresponding air temperatures differed between the montane and coastal field gliders, but were similar in coastal field and captive-bred gliders. Our study shows that morphology, behaviour and physiology can be strongly affected by breeding in or acclimation to captivity. The poor expression of torpor and thermal performance of the captive-bred gliders raises the question of whether they possess the physiological capability for survival in the wild. Even though captive breeding appears to have only minor effects on some physiological variables, data from captive-bred individuals should only be extrapolated to the field with caution.

Adaptation, Physiological↗

PubMed2001

A (1-->4)-beta-mannan-specific monoclonal antibody and its use in the immunocytochemical location of galactomannans.

Galactomannan was coupled to a protein carrier for the preparation of monoclonal antibodies. The monoclonal antibodies generated bound to galactomannans from different sources as well as to glucomannan and galactoglucomannan. One monoclonal antibody, BGM C6, was characterised and found to be specific for (1-->4)-beta-linked mannopyranosyl residues; it had a binding affinity estimated at 1x10(-6) M for the (1-->4)-beta-linked mannohexaose. BGM C6 was used in immunogold labelling studies to locate galactomannans in the endosperm walls of normal coconuts (Cocos nucifera L.) and those of the mutant makapuno at two different developmental stages. The pattern and intensity of antibody labelling varied for each type of coconut at the mature and immature stages, indicating differences in the galactomannan composition of the endosperm walls.

Antibodies, Monoclonal↗

PubMed2001

Personal exposure of workers to atmospheric PAHs on gasworks sites--The SOLEX study.

The aim of the SOLEX study was to estimate the personal exposure of workers to atmospheric polycyclic aromatic hydrocarbons (PAHs) on former gasworks sites in the Paris metropolitan area. Devices to sample gas and particulate phases for 9 PAHs were carried during one working day of a study week in November 1997 by 24 workers and in June 1998 by 19 workers with contrasted job profiles involving different opportunities for contact with the soil; among these volunteers, some were active in the process of contaminated soil remediation during the November study period. PAH concentrations were measured by high-performance liquid chromatography. Subjects working on the site under remediation were clearly more exposed (684.1 ng/m3 for total PAHs in November 1997) than workers, without close contact with soil, whose PAH exposure was similar to that measured by fixed monitors in the ambient air in Paris. The contrasts were weaker in June 1998, when soil remediation had nearly been completed. Only subjects involved in activities with close contact with the ground were found with exposures exceeding background levels. Further investigations are needed to improve our understanding of the influence of the pollutants present in the soil.

Adult↗

PubMed2000

Feasibility of assessing dermal exposure to PAHs of workers on gaswork sites--the SOLEX study.

Population exposure to pollutants in soil is an important public health concern. Difficult to measure, it is usually estimated using multimedia models. Modeling data predict that the skin surface is a predominant exposure route in roughly 15% of the US Superfund sites. Nonetheless, no study has confirmed these predictions. The SOLEX study was an opportunity to study the feasibility of estimating the cutaneous polycyclic aromatic hydrocarbons (PAHs: all 16 of the United States Environmental Protection Agency list) load of workers at three former manufactured gas sites, one of those being under remediation. Over two measurement periods (November 1997 and June 1998), 30 and 28 volunteers, respectively, were equipped for a single day work with five pads that collected soil particles and were placed at the neck, shoulder, wrist, groin, and ankle. Pad contamination was observed for six of the nine workers on the site being remediated but not on other sites. The wrist pad was most often affected, followed by the neck pad, these are, the exposed regions of the body. The PAHs most frequently identified were anthracene, fluoranthene, naphthalene, phenanthrene, and pyrene, at concentrations relatively high. In conclusion, this study showed that estimating skin exposure to soil pollutants is feasible. Secondly, it suggested that only subjects in close contact with the soil had a detectable exposure to PAHs. Extension of this approach to other exposure settings is warranted, especially among children playing in polluted public or private gardens, because their games lead to frequent contact with the soil.

Administration, Cutaneous↗

PubMed2000

Sequence and expression of the kettin gene in Drosophila melanogaster and Caenorhabditis elegans.

Kettin is a large modular protein associated with thin filaments in the Z-disc region of insect muscles. The sequence of a 21.3 kb contig of the Drosophila gene has been determined. The corresponding protein sequence has 35 immunoglobulin-like (Ig) domains which are separated by shorter linker sequences, except near the N and C termini of the molecule where linker sequences are short or missing. This confirms a model in which each Ig domain binds to an actin protomer. The Drosophila kettin gene is at 62C 1-3 on the third chromosome. Two P-element insertions, l(3)j1D7 and l(3)rL182 are in the kettin gene, and complementation tests showed that existing l(3)dre8 mutations are in the same gene. The RNA was detected in wild-type Drosophila embryos at stage 11, first in the gut invagination region of the mesoderm, and by stage 13 in both visceral and somatic mesoderm. Somatic mesoderm expression became segmental at stage 13. RNA expression was greatly reduced in embryos of P-element homozygotes but normal in heterozygotes. The structure of the flight muscle in all the heterozygous mutants was normal, including the myofibril-cuticle connections, and they were able to fly. Kettin sequence homologous to the Drosophila protein, was identified in the Caenorhabditis elegans genome database. The RNA was detected in pharyngeal, body wall and anal depressor muscles of larvae and adult worms, as well as in the male gonad. Antibody to insect kettin labelled the pharyngeal, body wall, anal depressor and proximal gonadal muscles in adult worms. Body wall muscles were labelled in an obliquely striated pattern consistent with the Z-disc localisation in insect muscle. The relationship of kettin to D-titin, which has been assigned to the same chromosomal locus in Drosophila, is discussed.

Amino Acid Sequence↗

PubMed2000

PART-1: a novel human prostate-specific, androgen-regulated gene that maps to chromosome 5q12.

Genes regulated by androgenic hormones are of critical importance for the normal physiological function of the human prostate gland, and they contribute to the development and progression of prostate carcinoma. We used cDNA microarrays containing 1500 prostate-derived cDNAs to profile transcripts regulated by androgens in prostate cancer cells. This study identified a novel gene that we have designated PART-1 (prostate androgen-regulated transcript 1), which exhibited increased expression upon exposure to androgens in the LNCaP prostate cancer cell line. Northern analysis demonstrated that PART-1 is highly expressed in the prostate gland relative to other normal human tissues and is expressed as different transcripts using at least three different polyadenylation signals. The PART-1 cDNA and putative protein are not significantly homologous to any sequences in the nonredundant public sequence databases. Cloning and analysis of the putative PART-1 promoter region identified a potential binding site for the homeobox gene PBX-la, but no consensus androgen response element or sterol-regulatory element binding sites were identified. We used a radiation hybrid panel and fluorescence in situ hybridization to map the PART-1 gene to chromosome 5q12, a region that has been suggested to harbor a prostate tumor suppressor gene. These results identify a new gene involved in the androgen receptor-regulated gene network of the human prostate that may play a role in the etiology of prostate carcinogenesis.

Amino Acid Sequence↗

PubMed2000

Links in the chain: the contribution of kettin to the elasticity of insect muscles.

Asynchronous flight muscle fibers are activated by periodic stretches and need to be stiff for strain to be transmitted to the contractile system. Kettin associated with thin filaments and projectin with thick filaments contribute to fiber stiffness. Kettin extends along thin filaments with the N-terminus in the Z-disc and the C-terminus outside. C filaments connecting thick filaments to the Z-disc contain projectin but not kettin. Insect flight myofibrils have a titin PEVK epitope which is only exposed on stretch, suggesting it is short and inaccessible. It is concluded that kettin stiffens thin filaments near the Z-disc and projectin and titin provide elasticity to C filaments.

Amino Acid Sequence↗

PubMed2000

A novel sensor for monitoring leakage of petroleum and other liquid hydrocarbons into soil environments.

This paper describes the use of a potentially implantable infrared reflectometer for the qualitative detection of petroleum and a number of other hydrocarbon solvents. A rugged, low-power, re-useable sensor was evaluated in the laboratory for its ability to detect petrol in soil. A hydrophobic fluoropolymer was used as the sensing surface due to its high selectivity for petroleum hydrocarbons. The photocurrent reflected by this surface from a near IR source was measured to test for petroleum saturation within the membrane, which in turn was an indicator of petroleum in the surrounding soil. The simplicity in the sensor design enabled a stable, low cost detection method for petroleum and other hydrocarbons, ideal for use in sub-surface applications.

Environmental Monitoring↗

PubMed2000

Macmillan Carers Schemes in England: results of a multicentre evaluation.

Maintaining sick and elderly people at home, particularly as they approach the end of life, is a long-established challenge for health and social care services. Over the past 30 years palliative care providers have attempted a variety of innovations in this area. We report on a descriptive study of seven pilot Macmillan Carers Schemes in England. The schemes sought to provide practical and emotional help to cancer patients and families living in their own homes. Data are available on 624 referrals to the schemes over a 1-year period. Emphasizing comparisons between schemes, we report on reasons for and sources of referral, services offered, number and duration of visits and tasks undertaken. We consider the views of informal carers who made use of the service, the perceptions of Macmillan carers themselves, and we compare financial costs of schemes. It is concluded that the schemes have the potential for further development but face problems, which reflect on their borderline position between 'health' and 'social care'. Current policy changes may be beneficial to the schemes in this respect.

Aged↗

PubMed2000

Nanomolar concentrations of inorganic lead increase Ca2+ efflux and decrease intracellular free Ca2+ ion concentrations in cultured rat hippocampal neurons by a calmodulin-dependent mechanism.

Inorganic lead (Pb2+) activates calmodulin, which in turn may stimulate many other cellular processes. The plasma membrane Ca2+ ATPase is a calmodulin-stimulated enzyme that plays the major role in regulating the "resting" intracellular free Ca2+ ion concentration, [Ca2+]i. We hypothesized that exposing neurons to low levels of Pb2+ would cause Pb2+ to enter the cytoplasm, and that intracellular Pb2+, by activating calmodulin, would stimulate plasma membrane Ca2+ ATPase activity, thereby increasing Ca2+ extrusion and reducing [Ca2+]i. We used the ratiometric Ca2+ indicator fura-2 to estimate changes in [Ca2+]i. In vitro calibrations of fura-2 with solutions of defined free Ca2+ and free Pb2+ concentrations showed that, at free Ca2+ concentrations from 10 nM to 1000 nM, adding Pb2+ caused either no significant change in the F340/F380 ratio (free Pb2+ concentrations from 100 fM to 1 pM) or increased the F340/F380 ratio (free Pb2+ concentrations from 5 to 50 pM). Therefore, fura-2 should be suitable for estimating Pb2+-induced decreases in [Ca2+]i, but not increases in [Ca2+]i. We exposed cultured embryonic rat hippocampal neurons to 100 nM Pb2+ for periods from 1 hour to 2 days and measured the F340/F380 ratio; the ratio decreased significantly by 9 to 16% at all time points, indicating that Pb2+ exposure decreased [Ca2+]i. In neurons loaded with 45Ca, Pb2+ exposure increased Ca2+ efflux for at least two hours; by 24 hours, Ca2+ efflux returned to control levels. Influx of 45Ca was not altered by Pb2+ exposure. Low concentrations (250 nM) of the calmodulin inhibitor calmidazolium had no effect on either 45Ca efflux or on the F340/F380 ratio in fura-loaded control neurons, but completely eliminated the increase in 45Ca efflux and decrease in F340/F380 ratio in Pb2+-exposed neurons. Zaldoride, another calmodulin inhibitor, also eliminated the decrease in F340/F380 ratio in Pb2+-exposed neurons. We conclude that Pb2+ exposure decreases [Ca2+]i and increases Ca2+ efflux in cultured hippocampal neurons by a calmodulin-dependent mechanism, probably by stimulating Ca2+ extrusion by the plasma membrane Ca2+ ATPase.

Animals↗

PubMed1999

Negative selection: a method for obtaining low-abundance cDNAs using high-density cDNA clone arrays.

The identification of the entire complement of genes expressed in a cell, tissue, or organism provides a framework for understanding biological properties and establishes a tool set for subsequent functional studies. The large-scale sequencing of randomly selected clones from cDNA libraries has been successfully employed as a method for identifying a large fraction of these expressed genes. However, this approach is limited by the inherent redundancy of cellular transcripts reflecting widely variant levels of gene transcription. As a result, a high percentage of transcript duplications are encountered as the number of sequenced clones accrues. To address this problem, we have developed a negative hybridization selection method that employs the hybridization of complex cDNA probes to high-density arrays of cDNA clones and the subsequent selection of clones with a null or low hybridization signal. This approach was applied to a cDNA library constructed from normal human prostate tissue and resulted in the reduction of highly expressed prostate cDNAs from 6.8 to 0.57% with an overall decline in clone redundancy from 33 to 11%. The selected clones also reflected a more diverse cDNA population, with 89% of the clones representing distinctly different cDNAs compared with 67% of the randomly selected clones. This method compares favorably with cDNA library re-association normalization approaches and offers several distinct advantages, including the flexibility to use previously prepared libraries, and the ability to employ an iterative screening approach for continued accrual of cDNAs representing rare transcripts.

DNA, Complementary↗

PubMed1999

Prostate-localized and androgen-regulated expression of the membrane-bound serine protease TMPRSS2.

Genes regulated by androgenic hormones are of critical importance for the normal physiological function of the human prostate gland, and they contribute to the development and progression of prostate carcinoma. We used cDNA microarrays containing 1500 cDNAs to profile transcripts regulated by androgens in prostate cancer cells and identified the serine protease TMPRSS2 as a gene exhibiting increased expression upon exposure to androgens. The TMPRSS2 gene is located on chromosome 21 and contains four distinct domains, including a transmembrane region, indicating that it is expressed on the cell surface. Northern analysis demonstrated that TMPRSS2 is highly expressed in prostate epithelium relative to other normal human tissues. In situ hybridization of normal and malignant prostate tissues localizes TMMPRSS2 expression to prostate basal cells and to prostate carcinoma. These results suggest that TMPRSS2 may play a role in prostate carcinogenesis and should be investigated as a diagnostic or therapeutic target for the management of prostate cancers.

Androgens↗

PubMed1999

Molecular cloning and characterization of prostase, an androgen-regulated serine protease with prostate-restricted expression.

The identification of genes with selective expression in specific organs or cell types provides an entry point for understanding biological processes that occur uniquely within a particular tissue. Using a subtraction approach designed to identify genes preferentially expressed in specific tissues, we have identified prostase, a human serine protease with prostate-restricted expression. The prostase cDNA encodes a putative 254-aa polypeptide with a conserved serine protease catalytic triad and an amino-terminal pre-propeptide sequence, indicating a potential secretory function. The genomic sequence comprises five exons and four introns and contains multiple copies of a chromosome 19q-specific minisatellite repeat. Northern analysis indicates that prostase mRNA is expressed in hormonally responsive normal and neoplastic prostate epithelial tissues, but not in prostate stromal constituents. Prostase shares 35% amino acid identity with prostate-specific antigen (PSA) and 78% identity with the porcine enamel matrix serine proteinase 1, an enzyme involved in enamel matrix degradation and with a putative role in the disruption of intercellular junctions. Radiation-hybrid-panel mapping localized prostase to chromosome 19q13, a region containing several other serine proteases, including protease M, pancreatic/renal kallikrein hK1, and the prostate-specific kallikreins hK2 and hK3 (PSA). The sequence homology between prostase and other well-characterized serine proteases suggests several potential functional roles for the prostase protein that include the degradation of extracellular matrix and the activation of PSA and other proteases.

Amino Acid Sequence↗

PubMed1999

Regulation of transforming growth factor-beta, basic fibroblast growth factor, and vascular endothelial cell growth factor mRNA in peripheral blood leukocytes in patients with diabetic retinopathy.

In the present study, we examined the effect of glucose concentration on the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta (TGF-beta) mRNA using reverse transcriptase-polymerase chain reaction (RT-betaCR) in normal healthy leukocytes in vitro and in leukocytes from patients with type 1 diabetes mellitus. In vitro, the level of TGF-beta mRNA was altered in response to the glucose concentration (maximum at 10 mmol/L), while bFGF mRNA remained relatively constant and VEGF mRNA varied with no clear correlation with the glucose concentration. Leukocytes from type 1 patients showed no difference in bFGF or TGF-beta mRNA levels compared with age-matched healthy controls. However, VEGF mRNA was significantly lower in type 1 patients compared with controls (P < .05). When the patients were subtyped according to the severity of retinopathy, the level of TGF-beta mRNA was elevated selectively in patients with evidence of active new retinal vessels (P < .01) and VEGF121 mRNA was reduced in patients with mild to moderate retinopathy. Thus, leukocyte growth factor mRNAs respond to acute changes in the glucose concentration in vitro, and are differentially expressed in type 1 diabetic patients during the course of the disease.

Adult↗

PubMed1999

Does adult fracture repair recapitulate embryonic skeletal formation?

Bone formation is a continuous process that begins during fetal development and persists throughout life as a remodeling process. In the event of injury, bones heal by generating new bone rather than scar tissue; thus, it can accurately be described as a regenerative process. To elucidate the extent to which fetal skeletal development and skeletal regeneration are similar, we performed a series of detailed expression analyses using a number of genes that regulate key stages of endochondral ossification. They included genes in the indian hedgehog (ihh) and core binding factor 1 (cbfa1) pathways, and genes associated with extracellular matrix remodeling and vascular invasion including vascular endothelial growth factor (VEGF) and matrix metalloproteinase 13 (mmp13). Our analyses suggested that even at the earliest stages of mesenchymal cell condensation, chondrocyte (ihh, cbfa1 and collagen type II-positive) and perichondrial (gli1 and osteocalcin-positive) cell populations were already specified. As chondrocytes matured, they continued to express cbfa1 and ihh whereas cbfa1, osteocalcin and gli1 persisted in presumptive periosteal cells. Later, VEGF and mmp13 transcripts were abundant in chondrocytes as they underwent hypertrophy and terminal differentiation. Based on these expression patterns and available genetic data, we propose a model where Ihh and Cbfa1, together with Gli1 and Osteocalcin participate in establishing reciprocal signal site of injury. The persistence of cbfa1 and ihh, and their targets osteocalcin and gli1, in the callus suggests comparable processes of chondrocyte maturation and specification of a neo-perichondrium occur following injury. VEGF and mmp13 are expressed during the later stages of healing, coincident with the onset of vascularization of the callus and subsequent ossification. Taken together, these data suggest the genetic mechanisms regulating fetal skeletogenesis also regulate adult skeletal regeneration, and point to important regulators of angiogenesis and ossification in bone regeneration.

Aging↗