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Biomedical subjects

C H Smith

Publications and source records attributed to C H Smith.

At least 19 recordsLinked to original sources
PubMed2006

IGF regulation of neutral amino acid transport in the BeWo choriocarcinoma cell line (b30 clone): evidence for MAP kinase-dependent and MAP kinase-independent mechanisms.

OBJECTIVE: IGF-1 and IGF-1 receptors are major determinants of fetal growth and are expressed primarily on the maternal-facing surface of the syncytiotrophoblast cell membrane in the human placenta. IGF-1 regulates fetal growth, in part, by regulating amino acid transport across the placenta. The objective of these studies was to study the role of IGF-1 and its signaling pathway in regulating neutral amino acid transport in a human trophoblast cell culture model. DESIGN: The regulation of neutral amino acid transport by IGF-1 was studied in cultured BeWo(b30) choriocarcinoma cells using the non-metabolizing amino acid analog, [(3)H]-alpha-aminoisobutyric acid (AIB). Transport in the absence of Na was used to distinguish system L from total AIB transport. Similarly, Na-dependent transport in the presence of excess methyl-AIB (MeAIB) permitted discrimination of systems A (MeAIB-sensitive) and ASC (MeAIB-insensitive). Specific inhibitors of intracellular signaling pathways were then used to determine the signaling pathway utilized by IGFs to regulate each amino acid transport system. Specificity of inhibition was assessed using specific markers of p70 S6 kinase activity and MAP kinase activation. RESULTS: Maximal stimulating concentrations of IGF-I (100 ng/ml) stimulated AIB transport by 30-40% exclusively through system A. Wortmannin (100 nM), an inhibitor of PI-3-kinase activity, inhibited all IGF-I-stimulated transport. Rapamycin (100 ng/ml), an inhibitor of p70 S6 kinase, and bisindolylmaleimide, an inhibitor of protein kinase C (PKC), had no effect. PD-098059 (50 miccroM), an inhibitor of MAP kinase activation, inhibited 20-30% of basal AIB transport but did not inhibit IGF-I-stimulated transport under the conditions studied. IGF-1 did not increase steady state mRNA levels of the system A transporters, SNAT1 and SNAT2, suggesting IGF-1 stimulates transport via post-transcriptional mechanisms. CONCLUSIONS: These data demonstrate that IGF-I stimulates neutral amino acid transport system A by a PI3-kinase dependent, post-transcriptional pathway in the BeWo(b30) cell line. Additionally, system A activity appear to be sensitive to MAP kinase-dependent pathways not regulated by IGFs.

Amino Acid Transport System A↗
PubMed2006

Apolipoprotein E gene polymorphisms are associated with psoriasis but do not determine disease response to acitretin.

BACKGROUND: Psoriasis is associated with abnormal plasma lipid metabolism and a high frequency of cardiovascular events. Increased lipid levels are also seen in patients with psoriasis treated with acitretin. Apolipoprotein E (ApoE) variants have been linked to hypertriglyceridaemia and hypercholesterolaemia in normal individuals. Two coding single nucleotide polymorphisms at +3937 and +4075 define the three common ApoE alleles e2, e3 and e4. OBJECTIVES: To test the hypothesis that particular ApoE polymorphism(s) are associated with psoriasis and that specific ApoE allelic variant(s) may be a marker for predicting disease response to acitretin. METHODS: DNA was genotyped for ApoE polymorphisms using a radioactive hybridization technique in cohorts of patients with psoriasis, including patients with chronic plaque psoriasis (CPP, n = 212), guttate psoriasis (GP, n = 94), palmoplantar pustulosis (PPP, n = 101), controls (n = 137), acitretin responders (n =106) and acitretin nonresponders (n = 84). RESULTS: The frequency of the e4 allele (+3937C/+4075C) was significantly higher in patients with CPP and GP than in controls (P = 0.008 and P = 0.02, respectively). There was no significant difference in allele frequencies between patients with PPP and controls. Allelic distribution was similar in acitretin responders and nonresponders. CONCLUSIONS: These data demonstrate an association between the Apo e4 allele and CPP and GP, suggesting a possible pathogenic role for ApoE in psoriasis. Our results do not support a link between disease response to acitretin and the e2, e3 or e4 allelic variants of ApoE.

Acitretin↗
PubMed2006

Infliximab for severe, treatment-resistant psoriasis: a prospective, open-label study.

BACKGROUND: Infliximab, a mouse-human chimeric monoclonal antibody directed against tumour necrosis factor-alpha, has been shown to be effective for moderate to severe psoriasis, but there are few data published on its use in recalcitrant, treatment-resistant disease or in combination with other antipsoriatic therapies. OBJECTIVES: To report our experience with infliximab in the treatment of patients attending a tertiary referral service with severe recalcitrant disease. METHODS: All patients attending a tertiary referral service for severe psoriasis who were treated with infliximab between 2002 and July 2005 were entered into a prospective, open-label study. Details on disease phenotype, clinical course and adverse events were recorded together with measures of disease severity [Psoriasis Area and Severity Index (PASI), Dermatology Life Quality Index, clinical photography] at baseline, weeks 2 and 6, and then at 2-monthly intervals throughout the treatment period. RESULTS: Twenty-three patients were treated with infliximab during the study; one patient had pustular psoriasis and was therefore excluded from statistical analysis. All had severe disease (baseline PASI 26.5+/-6.7, mean+/-SD, n=22) and had received at least two systemic therapies for psoriasis in the past; 16 were taking one or more concomitant therapies at the time of treatment initiation. At week 10, 95% had achieved a 50% or greater improvement in baseline PASI (PASI 50), and 77% had achieved a 75% or greater improvement (PASI 75). Efficacy was sustained in the longer term, with eight of 10 patients on treatment for more than 11 months maintaining at least a PASI 50. Only one patient had treatment withdrawn due to lack of efficacy, two suffered severe systemic infections including extrapulmonary tuberculosis (splenic abscess) and cellulitis, and six have discontinued due to adverse effects including infusion reactions (two), severe thrombocytopenia (one), hepatitis (one) and malignancy (two). CONCLUSIONS: Data from this open-label study suggest that infliximab is a rapidly effective treatment for patients with severe, treatment-resistant disease, although approximately 25% of patients had to discontinue therapy due to the development of serious adverse effects. Long-term follow-up, continued pharmacovigilance, and further controlled comparative studies will be required to evaluate fully the risks associated with infliximab in the context of this already difficult to treat population.

Abscess↗
PubMed2006

Killed Mycobacterium vaccae suspension in children with moderate-to-severe atopic dermatitis: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: The hygiene hypothesis is often proposed to explain the high prevalence of atopy in the western world. Dysregulation of the immune system may result from inadequate exposure to micro-organisms such as mycobacteria. A small trial suggested that a killed extract of Mycobacterium vaccae ameliorates atopic dermatitis (AD). OBJECTIVES: To confirm in a large clinical trial whether killed M. vaccae ameliorates AD in 5-16-year-old children. METHODS: This was a randomized, placebo-controlled, double-blind, multi-centre study of the effect of intradermal injection of killed M. vaccae (0.1 or 1 mg) on patients, aged 5-16, with moderate-to-severe AD. Patients were followed up for 24 weeks. The primary end point was the change in severity of AD at 12 weeks, assessed using the six area, six-sign, atopic dermatitis (SASSAD) score. Secondary end points included changes in disease extent, patient's global assessment and children's dermatology life quality index. RESULTS: There were 166 patients randomized. The mean SASSAD score fell to a similar degree at week 12 in all treatment arms: from 33 to 24, (26%) in the high-dose group, from 30 to 23 (25%) in the low-dose group and from 36 to 27 (24%) in the placebo group (P>0.05). Secondary end points followed the same trend. Adverse events were generally those expected to occur in this population. Injection site reactions occurred in 32 patients at week 4. CONCLUSIONS: M. vaccae was no more effective than the placebo in ameliorating the severity of AD.

Adolescent↗
PubMed2005

Does topical tacrolimus induce lentigines in children with atopic dermatitis? A report of three cases.

Three children with severe atopic dermatitis were noted at routine follow-up to have developed multiple small pigmented macules during long-term therapy with topical tacrolimus 0.1% (Protopic, Fujisawa). Representative lesions in two of the three cases were confirmed histologically as simple lentigines. The focal distribution of lentigines to sites of tacrolimus use, and the temporal association between use of tacrolimus and development of lesions, suggest that topical tacrolimus is of direct aetiological relevance to their development. Careful long-term follow-up will be required to assess the clinical implications of these findings and whether they represent an increase in risk for melanocytic neoplasia.

Administration, Cutaneous↗
PubMed2005

Replacement of routine liver biopsy by procollagen III aminopeptide for monitoring patients with psoriasis receiving long-term methotrexate: a multicentre audit and health economic analysis.

BACKGROUND: Patients receiving long-term methotrexate for psoriasis are at risk of developing hepatic fibrosis. Repeated liver biopsy has long been regarded as the only reliable method of detecting this and it is still recommended by the American Academy of Dermatology (AAD). More recently, monitoring by serum procollagen III aminopeptide (PIIINP) measurement (Orion Diagnostica, Espoo, Finland) has been advocated as a means of significantly reducing the need for liver biopsy. OBJECTIVES: To assess the validity of guidelines developed in Manchester for the use of PIIINP to monitor patients with psoriasis receiving long-term methotrexate; to assess the anticipated benefits to patients of introducing this change in practice, including reduction in requirement for liver biopsy; and to determine the impact of its introduction on healthcare costs. METHODS: A multicentre audit was conducted over a 24-month period to compare the healthcare costs and outcomes of two intervention groups from centres where serial PIIINP measurement was employed with those of two control groups from centres in which AAD guidelines were followed. RESULTS: A sevenfold reduction in the need for liver biopsy was observed in the two intervention groups (n = 166; 0.04 and 0.02 biopsies/patient/year, respectively) compared with the two control groups (n = 87; 0.26 and 0.30 biopsies/patient/year, respectively). Abnormalities of sufficient severity to influence management were identified in one in five patients biopsied in the main intervention group compared with one in 16 in the control groups. The overwhelming majority of patients surveyed expressed a preference for being monitored by methods that would minimize the need for liver biopsy. The adoption of PIIINP for monitoring would result in significant cost savings. CONCLUSIONS: This audit has shown that patients managed by the Manchester protocol using serial PIIINP measurement and selective liver biopsy were not disadvantaged in comparison with those managed according to AAD guidelines; they were subjected to sevenfold fewer liver biopsies without evidence that important liver toxicity was missed in the process. If PIIINP monitoring were widely adopted, methotrexate would become a more acceptable option for many patients who are dissuaded from considering it because of the threat of repeated liver biopsy; it would also result in significant savings to the healthcare budget.

Adult↗
PubMed2004

Successful treatment of severe psoriasis and psoriatic arthritis with adalimumab.

Adalimumab, a fully human-derived recombinant monoclonal antibody against tumour necrosis factor-alpha, has been shown to be effective for the treatment of patients with moderately to severely active rheumatoid arthritis. We report two patients with long-standing recalcitrant psoriasis and psoriatic arthritis who, after multiple treatment failures with conventional and experimental antipsoriatic medications, both responded to treatment with adalimumab. Significant clinical improvement was noted in both skin and joint disease in the two patients after several weeks of treatment with adalimumab. We are unaware of previous published reports of adalimumab therapy in patients with psoriasis and psoriatic arthritis.

Adalimumab↗
PubMed2004

Further additions to the bibliography of Alfred Russel Wallace (1823-1913).

Twenty-one previously unrecorded published writings by the English naturalist Alfred Russel Wallace (1823-1913) are noticed. The writings vary greatly in date, size and importance, and include items pertaining both to Wallace's natural history as well as social and political interests

Bibliography of Medicine↗
PubMed2003

Isoforms of amino acid transporters in placental syncytiotrophoblast: plasma membrane localization and potential role in maternal/fetal transport.

Many cell proteins exist as isoforms arising either from gene duplication or alternate RNA splicing. There is growing evidence that isoforms with different, but closely related, functional characteristics are often directed to discrete cellular locations. Thus, specialized functions may be carried out by proteins of similar evolutionary origin in different membrane compartments. In polarized epithelial cells, this mechanism allows the cell to control amino acid transport independently at each of its specialized apical and basolateral plasma membrane domains. Investigations of isoform localization in these membranes have generally been performed in epithelia other than the placental trophoblast.This review of placental amino acid transporter isoforms first provides an overview of their properties and preliminary plasma membrane localization. We then discuss studies suggesting various roles of isoform localization in trophoblast function. To provide insights into the molecular basis of this localization in trophoblast, we present a review of current knowledge of plasma membrane protein localization as derived from investigations with a widely used epithelial model cell line. Finally, we discuss a potential approach using cultured trophoblast-derived cells for studies of transporter isoform localization and function. We hope that this review will stimulate investigation of the properties of trophoblast transporter isoforms, their membrane localization and their contribution to the cellular mechanism of maternal-fetal nutrient transport.

Adult↗
PubMed2002

Hypoxia reduces expression and function of system A amino acid transporters in cultured term human trophoblasts.

We tested the hypothesis that hypoxia diminishes the expression and transport of neutral amino acids by system A in full-term human trophoblasts. Cytotrophoblasts from normal human placentas were cultured in standard conditions of 20% O(2) or in 1% and 3% O(2) for 24 h before assay. Neutral amino acid transport for systems A, ASC, and L was assayed at 24 and 72 h by the cluster-tray technique. Hypoxia during the initial 24 h of culture reduced system A transport by 82% in 1% O(2) and by 37% in 3% O(2) (P < 0.01) compared with standard conditions. Hypoxia during the latter 24 h of the 72 h in culture reduced system A transport by 55% in 1% O(2) and by 20% in 3% O(2) (P < 0.05) compared with standard conditions at 72 h. Hypoxia (1% O(2)) also reduced total amino acid transport by 40% in the more differentiated syncytiotrophoblasts present at 72 h. Northern analysis of trophoblasts in standard conditions showed that subtypes of human amino acid transporter A (hATA1 and hATA2) were each expressed in cytotrophoblasts and syncytiotrophoblasts. Hypoxia decreased expression of hATA1 and hATA2 in both trophoblast phenotypes. We conclude that hypoxia downregulates system A transporter expression and activity in cultured human trophoblasts.

Amino Acid Transport System A↗
PubMed2002

Lysine uptake by cloned hCAT-2B: comparison with hCAT-1 and with trophoblast surface membranes.

To study the cationic amino-acid transporter hCAT-2B of human placenta, total RNA was harvested from primary cultured trophoblast and from the BeWo choriocarcinoma cell line (b30 clone) and used for reverse transcription (RT) and polymerase chain reaction (PCR). Primers based on published sequences identified expression of mRNA for hCAT-2B. RT-PCR yielded a 2.06 kb hCAT-2B cDNA, which was cloned. hCAT-2B cRNA injection into Xenopus laevis oocytes stimulated saturable lysine uptake (Km approximately 125 mM). In the presence of Na+, uptake was completely inhibited by L-arginine but only partially by neutral amino acids. To compare directly the interaction of hCAT-1 and hCAT-2B with neutral amino acids and sodium, we examined the inhibition of these transporters by L-leucine and L-alanine over a wide concentration range. L-Alanine and L-leucine inhibit uptake by hCAT-2B substantially less completely than uptake by hCAT-1. The interaction of hCAT-2B resembles that of system y+ in the microvillous membrane of human placenta, while that of hCAT-1 is more comparable to that of system y+ in basal membrane. The identification and characterization of the various cationic amino-acid transporters of the human placenta have the potential to increase the understanding of the cellular mechanism of transplacental transfer.

Alanine↗
PubMed2002

Stable polarized expression of hCAT-1 in an epithelial cell line.

Our laboratory has recently identified and cloned three cationic amino-acid transporters of human placenta. We have now examined the plasma membrane domain localization and functional expression of one of these transporters, hCAT-1, in a polarized epithelial cell line (MDCK). To facilitate identification of expressed protein we first transferred the hCAT-1 cDNA to a vector with C-terminal green fluorescent protein (GFP). The resultant hCAT-1-CT-GFP fusion protein stimulated L-[3H] lysine uptake in Xenopus oocytes. In confluent monolayers of stably transfected cells grown on porous nitrocellulose filters, saturable uptake of L-[3H] lysine from the basolateral surface was stimulated 7-fold over that of untransfected cells. Concentration-dependence studies in Na+-free medium at pH 7.4 demonstrated a Km of approximately 68 +/- 13 microM and a Vmax of 970 +/-170 pmol/mg protein/min. Uptake from the apical plasma membrane surface was negligible in both transfected and untransfected cells. Consistent with these results, confocal microscopy of confluent monolayers of hCAT-1-CT-GFP-expressing cells revealed localization of the transporter solely on the basolateral domain of the cell. This is apparently the first report of a cultured polarized epithelial cell model for stable expression of a cationic amino-acid transporter. It has the potential to aid in the identification of targeting signals for transport protein localization.

Animals↗
PubMed2002

Pharmacogenetics in clinical dermatology.

Systemic therapies are increasingly used in the management of common skin diseases, and drug toxicity and relative lack of efficacy remain significant problems. In addition, we are unable to predict life-threatening adverse reactions such as toxic epidermal necrolysis. Pharmacogenetics, the study of how genetic differences influence the variability of individual patient responses to drugs, aims to distinguish responders from non-responders and predict those in whom toxicity is likely. Successful application of pharmacogenetics should lead to rationalized drug therapy. Recent advances in molecular genetic techniques such as high-throughput genotyping and microarrays have the potential to provide a practicable and economical approach to future pharmacogenetic testing. Pharmacogenetics will change not only the way drugs are selected but will also impact on clinical trial design and the costs of healthcare delivery.

Dermatology↗
PubMed2002

Swallowing and voice effects of Lee Silverman Voice Treatment (LSVT): a pilot study.

OBJECTIVE: To define the effects of Lee Silverman Voice Treatment (LSVT on swallowing and voice in eight patients with idiopathic Parkinson's disease. METHODS: Each patient received a modified barium swallow (MBS) in addition to voice recording before and after 1 month of LSVT. Swallowing motility disorders were defined and temporal measures of the swallow were completed from the MBS. Voice evaluation included measures of vocal intensity, fundamental frequency, and the patient's perception of speech change. RESULTS: before LSVT, the most prevalent swallowing motility disorders were oral phase problems including reduced tongue control and strength. Reduced tongue base retraction resulting in residue in the vallecula was the most common disorder in the pharyngeal stage of the swallow. Oral transit time (OTT) and pharyngeal transit time (PTT) were prolonged. After LSVT, there was an overall 51% reduction in the number of swallowing motility disorders. Some temporal measures of swallowing were also significantly reduced as was the approximate amount of oral residue after 3 ml and 5 ml liquid swallows. Voice changes after LSVT included a significant increase in vocal intensity during sustained vowel phonation as well as during reading. CONCLUSIONS: LSVT seemingly improved neuromuscular control of the entire upper aerodigestive tract, improving oral tongue and tongue base function during the oral and pharyngeal phases of swallowing as well as improving vocal intensity.

Aged↗
PubMed2001

Differential susceptibility of heart, skin, and islet allografts to T cell-mediated rejection.

Although it is widely accepted that there is a hierarchy in the susceptibility of different allografts to rejection, the mechanisms responsible are unknown. We show that the increased susceptibility of H-2K(b+) skin and islet allografts to rejection is not based on their ability to activate more H-2K(b)-specific T cells in vivo; heart allografts stimulate the activation and proliferation of many more H-2K(b)-specific T cells than either skin or islet allografts. Rejection of all three types of graft generate memory cells by 25 days posttransplant. These data provide evidence that neither tissue-specific Ags nor, surprisingly, the number of APCs carried in the graft dictate their susceptibility to T cell-mediated rejection and suggest that the graft microenvironment and size may play a more important role in determining the susceptibility of an allograft to rejection and resistance to tolerance induction.

Animals↗
PubMed2001

Effects of xerostomia on perception and performance of swallow function.

BACKGROUND: Head and neck cancer treatment with high-dose chemoradiation may cause xerostomia and affect the patient's perception of swallowing ability. METHOD: Whole saliva production was measured in 36 patients with advanced-stage cancer of the oropharynx before treatment and 3 months after treatment by weighing a 4 x 4 inch gauze before and after a 2-minute chewing period. Presence of multiple eating difficulties was measured by patient interview. Swallowing was examined videofluorographically (VFG). RESULTS: Saliva weight decreased from a mean (SEM) of 5.1 (0.5) g pretreatment to 1.4 (0.5) g after treatment (p<.0001). At 3 months, significantly more patients perceived difficulty swallowing, dry mouth, needing water while eating, food stuck in the mouth or throat, and change in taste. Saliva weight was not correlated with VFG measures of bolus transit or observations of residue. CONCLUSIONS: Chemoradiation treatment results in xerostomia and a significant increase in patient perception of swallowing difficulties. Saliva weight in patients who perceive swallowing problems was lower. Xerostomia did not affect the physiologic aspects of bolus transport. Xerostomia affected the sensory process and comfort of eating more than bolus transport.

Adult↗