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Biomedical subjects

S Hughes

Publications and source records attributed to S Hughes.

At least 163 records · Page 9Linked to original sources
PubMed1993

Autoantibodies to the GLUT-2 glucose transporter of beta cells in insulin-dependent diabetes mellitus of recent onset.

Purified immunoglobulin G (IgG) from the serum of patients with insulin-dependent diabetes mellitus (IDDM) of recent onset inhibits high-Km uptake of 3-O-methyl-beta-D-glucose by rat pancreatic islets. To determine if the inhibition is the result of antibodies against GLUT-2, the high-Km glucose transporter of beta cells, we incubated IDDM sera with rat islet cells and with AtT-20ins cells transfected to express GLUT-2. IDDM sera inhibited glucose uptake in islet cells and in GLUT-2-expressing AtT-20ins cells but not in AtT-20ins cells transfected to express the low-Km isoform, GLUT-1. In 24 of 30 (77%) patients with newly diagnosed IDDM, IgG binding as measured by immunofluorescence and flow cytometry of the cells transfected to express GLUT-2 was > 2 standard deviations from the mean of the nondiabetic population; 29 of 31 (96%) of nondiabetic children were negative (P < 0.0001). Increased IgG binding could be removed by absorption with GLUT-2-expressing cells but not with GLUT-1-expressing cells. We conclude that most patients with IDDM of recent onset have autoantibodies to GLUT-2.

3-O-Methylglucose↗
PubMed1993

Joint impairment and ambulation in the elderly.

OBJECTIVE: To test the impact of joint impairment on ambulation in the elderly, using a multivariate model. DESIGN: Cross-sectional observational study (baseline data from an ongoing longitudinal study). SUBJECTS: Five hundred thirty-two persons over age 60, including continuing care retirement community (CCRC) (n = 222), homebound (n = 63), and ambulatory (n = 247) respondents. Mean age at assessment = 76.6 (SD = 6.6). MEASUREMENT: Independent variables included sociodemographics, physician measures of lower joint impairment, an index of cormorbidities derived from physical examination or chart abstract, self-assessed arthritis pain, depression, and anxiety. The dependent variable, ambulation, was measured as walk-rate, based on the time required to walk 50 feet. MAIN RESULTS: For the total sample, 61% of the subjects were impaired in more than one lower joint group, with almost 50% of the homebound impaired in more than three joint groups. Demographics (particularly age and education) explained much of the variance in walk-rate. After controlling for demographics and membership in the groups purposely sampled (CCRC, homebound, ambulatory), lower joint impairment accounted for an additional 7% of the variance in walk-rate. Total amount of variance explained by the model was 56% (Adjusted R2 = .56). A 3-point change in lower joint impairment score, equivalent to the maximum impairment score for a single joint group, is associated with a 4-second change in the mean time required to walk 50 feet. The knee and lower spine joints contributed most to the impact of the lower joint impairment measure. CONCLUSIONS: Among the elderly, age and education are strong predictors of performance on a walk-rate test. Independent of demographics and non-musculoskeletal conditions, joint impairment is associated with diminished walking ability in this population.

Activities of Daily Living↗
PubMed1993

Heart rate perturbation in the stage 17-27 chick embryo: effect on stroke volume and aortic flow.

Heart rate (HR), stroke volume (SV), and aortic flow increase linearly between developmental stages 17 and 27, as the embryonic chick heart progresses from a bent tube to a rudimentary four-chambered structure and cardiac mass increases fourfold. We hypothesized that HR perturbation, expressed as percent of intrinsic HR (%HR), would have a developmentally dependent effect on flow and SV. HR was transiently perturbed to 40-250% of intrinsic rate with a 1-mm cooled or heated steel probe applied to the sinus venosus of 81 embryos. Aortic blood velocity, cross-sectional area, and HR were used to calculate flow and SV. At each stage, flow was maximal at intrinsic HR. The %HR vs. SV relationship was linear, inverse, and developmentally dependent. In spite of a tremendous change in ventricular shape, mass, and volume, HR control during development of the preinnervated heart maximizes blood flow to the developing embryo.

Animals↗
PubMed1993

Computed tomography of the sacroiliac joints in children.

Clinical assessment of the sacroiliac joints is difficult. Conventional radiography and radionuclide scanning have not afforded optimal sensitivity and specificity in the diagnosis of sacroiliac involvement in spondyloarthropathies. This report describes a technique for computed tomography of the sacroiliac joints in children; the method involves coronal scanning and allows assessment of the entire surface of the joints.

Adolescent↗
PubMed1992

Immunochemical characterisation of parathyroid hormone-related protein from tumour and non-tumour cells.

The molecular forms of parathyroid hormone-related protein (PTHRP) in conditioned media from the BEN human lung cancer cell line, rat parathyroid cells (PT-r) and human keratinocytes were studied by gel-filtration chromatography with assay of PTHRP by immunoassays and bioassay. Immunoreactivity (1-86 and 1-34) and bioactivity (1-34) in conditioned media eluted as a coincident major peak (approx. molecular mass 19-22 kDa) and there was evidence of amino-terminal species in the molecular mass range 10-16 kDa in BEN and keratinocyte media. Western blotting of PTHRP affinity purified by monoclonal antibodies directed at regions 1-34 or 37-67, identified a major species in all cell cytosols and media with an apparent molecular mass of 24-25 kDa, consistently slightly larger than recombinant PTHRP(1-141) (mobility of 21 kDa) which may represent an intact or native form of PTHRP. Additional amino-terminal species were identified in medium from keratinocytes (16 and 7 kDa), BEN cells (18 and 14 kDa) and PT-R cells (17 kDa), suggesting that processing occurs at the C-terminus and within the mid-region to form a range of amino-terminal fragments.

Animals↗
PubMed1992

Expression of insulinlike growth factor (IGF) and IGF-binding protein genes in human lung tumor cell lines.

BACKGROUND: The presence of multiple, low-molecular-weight, insulinlike growth factor (IGF)-binding proteins in lung tumor cell-conditioned medium and lung cancer patient serum has been recently reported. PURPOSE: To begin to elucidate the genetic basis for these observations, the present study examines the expression by lung tumor cell lines of three IGF-binding protein genes, namely, IGFBP-1, IGFBP-2, and IGFBP-3. Since IGF-binding proteins are thought to modulate the biologic action of the IGFs, the relationship between the expression of IGF-binding protein genes and the genes encoding IGF-I and IGF-II also has been investigated. METHODS: Gene expression was studied in four small-cell lung cancer (SCLC) and three non-small-cell lung cancer (NSCLC) cell lines using Northern blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR) for IGFBP-1. RESULTS: IGFBP-1 gene expression was detected by Northern blot analysis in one NSCLC cell line only. However, RT-PCR revealed that the IGFBP-1 gene was expressed in all four SCLC cell lines and in two of the three NSCLC lines. Northern blot analysis of IGFBP-2 gene expression demonstrated that all lung tumor cell lines expressed this gene. A low level of IGFBP-3 gene expression was detected in one SCLC cell line and in all three NSCLC cell lines. All lung tumor cell lines expressed the IGF-II gene as determined by Northern blot analysis. In marked contrast, none of the lines showed evidence of IGF-I gene expression using this method. However, RT-PCR revealed a low level of IGF-I gene expression in one SCLC and one NSCLC cell line only. CONCLUSIONS: These observations indicate 1) that IGF-binding proteins secreted by lung tumors are encoded by at least three different genes; 2) that there may be a close association between IGF-II and IGFBP-2 gene expression, such that, where there is production of IGF-II, IGFBP-2 is the principal BP; and 3) that the IGF-II gene is more widely expressed than the IGF-I gene in human lung tumor cell lines.

Base Sequence↗
PubMed1992

Production and characterisation of monoclonal antibodies to the mid-region 37-67 sequence of parathyroid hormone-related protein.

The production and characterisation of monoclonal antibodies (MAb) to the mid-region sequence 37-67 of human parathyroid hormone-related protein (PTHRP) is described. In spite of the poor immunogenicity of this sub-fragment of PTHRP, a high percentage of specific hybrids were produced by boosting with conjugate and free peptide prior to cell fusion. Seven of the MAbs produced cross-reacted with PTHRP37-67, PTHRP1-86 and native forms of PTHRP. Inhibition studies with peptide sub-fragments of PTHRP37-67 indicated that the majority recognised the 45-59 region. In a RIA for PTHRP1-86, detection limits ranged from 0.17 to 0.9 ng PTHRP1-86/tube, and no cross-reaction was found with PTH1-84. Two MAbs 1D11 and 4B10 were shown to be of potential use in measuring PTHRP1-86 in a two-site immunoradiometric assay in combination with either a solid phase consisting of a MAb to PTHRP1-34, or iodinated affinity purified rabbit antibodies to PTHRP1-34. MAb 1D11 coupled to Sepharose was suitable for immunoextraction of PTHRP, and successfully localised PTHRP on immunoblots. Two additional MAbs were produced which recognised an epitope unique to PTHRP37-67 located in the 37-46 region of the peptide.

Animals↗
PubMed1992

Effects of clearfelling on stream and soil water aluminium chemistry in three UK forests.

Data are presented demonstrating how clearfelling has changed soil and stream water aluminium chemistry. For soil waters, a strong empirical relationship was observed between inorganic aluminium (Al(inorg)) and total inorganic anion (TIA) concentrations. Before felling, chloride and sulphate accounted for the largest proportion of the TIA concentration. After felling, in soils where nitrification was active, nitrate became increasingly important. Where this led to an increase in TIA, Al(inorg) concentrations increased. Over five years, nitrate concentrations have fallen, along with TIA, resulting in a sympathetic decline in Al(inorg). Streams draining clearfelled areas initially became more acid, although chloride and sulphate concentrations decreased. Stream water nitrate concentrations increased soon after felling and remained higher than controls for up to four years. While nitrate concentrations were high, Al(inorg) remained unchanged. Subsequently, as nitrate and TIA decreased, Al(inorg) also declined to concentrations below those in the control stream. Clearfelling upland forests will not necessarily result in immediate improvements in water quality, although long-term benefits may be seen before canopy-closure of the next crop.

Journal Article↗
PubMed1992

Beta-endorphin and corticotropin immunoreactivity and specific binding in the neuromuscular system of obese-diabetic mice.

Immunoreactivity for two derivatives of pro-opiomelanocortin, beta-endorphin and alpha-melanocortin (or corticotropin), was demonstrated, using a conventional immunoperoxidase method, in some of the intramuscular nerves in muscle sections from obese diabetic (ob/ob) mice and homozygous lean (+/+) mice. The endplate regions were visualized in the sections by staining for acetylcholinesterase reaction product. The proportion of muscle endplates with beta-endorphin-immunoreactive motor nerves was approximately 2.5-fold higher in soleus and extensor digitorum longus muscles and approximately 1.5-fold higher in the diaphragm of the obese (ob/ob) mice compared to the normal lean mice. The proportion of muscle endplates with alpha-melanotropin-immunoreactive motor nerves was between 30 and 53% lower, depending on the muscle type, in the ob/ob mice compared to the lean mice. The muscles of ob/ob and lean mice were investigated for the presence of specific binding sites for [125I]beta-endorphin and for [125I]corticotropin, using autoradiography. Some muscle fibres in soleus, extensor digitorum longus and diaphragm in both the ob/ob and the lean mice exhibited specific binding sites for the radioactive ligands. The binding sites were distributed over the entire surface in these muscle fibres. In the ob/ob mice the number of muscle fibres with specific [125I]beta-endorphin binding sites was six-fold higher in soleus and approximately 10-fold higher in extensor digitorum longus and diaphragm, than in the corresponding muscles of the lean mice. In contrast, the number of muscle fibres with specific [125I]corticotropin binding sites was similar in obese (ob/ob) and lean mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1992

Outcome of treatment subsequent to the elective cryopreservation of all embryos from women at risk of the ovarian hyperstimulation syndrome.

From 1st June 1989 to 31st May 1991, 78 women with a serum oestradiol level greater than 3500 pg/ml on the day of the ovulatory trigger, following pituitary suppression with buserelin and ovarian stimulation with human menopausal gonadotrophins (HMG), had all their embryos electively cryopreserved at the pronucleate stage to minimize the risk of developing ovarian hyperstimulation syndrome (OHS). Treatment with buserelin was continued in the luteal phase. A median of 19 oocytes (range 7-43) was obtained and 12 embryos (range 1-37) frozen per cycle. Twenty-one (27%) women developed OHS (six severe). Women developing OHS had higher (P less than 0.05) serum oestradiol concentrations on the 7th day after oocyte retrieval, compared to those who did not. No differences were found for any of the following criteria: aetiology of infertility, age, total dose of HMG, number of oocytes, fertilization rate or freeze-thaw survival of embryos. Subsequently, 125 frozen-thawed embryo replacements have been undertaken, using buserelin and hormone replacement therapy (HRT) (n = 93) or natural cycles (n = 32). The overall freeze-thaw survival and implantation rates per embryo were 71.8 and 11.7%, respectively. The pregnancy rates in natural cycles (19%) and buserelin/HRT cycles (29%) were not significantly different.

Buserelin↗
PubMed1992

Enzymes in saliva from four parasitic arthropods.

Enzyme assays and SDS polyacrylamide gel electrophoresis were carried out on saliva and in some cases homogenates of salivary gland and gut from four parasitic arthropods (the cattle tick, Boophilus microplus (Canestrini); the mosquito, Aedes aegypti (L.); non-parasitic adult and parasitic larval blowfly of sheep, Lucilia cuprina (Wiedemann); the buffalo fly, Haematobia irritans exigua de Meijere). Saliva from all species showed large differences in the number and molecular weight of components, as judged by electrophoresis. Enzyme profiles, however, showed similar enzyme activities (phosphatase, esterase/lipase) in saliva from species with dissimilar feeding behaviours. There were obvious differences in the enzyme profiles of saliva and gut tissues from the different species that reflected feeding strategies. These differences were mainly in the type and levels of glycosidase and protease activities. It was concluded that many of the components of saliva from different species had similar functions, although a small number of them may be specifically adapted to the mode of feeding for each parasite.

Aedes↗
PubMed1992

Comparative evaluation of rate modulation in new generation evoked QT and activity sensing pacemakers.

Two new generation rate adaptive pacemakers, the Rhythmyx (Vitatron) using the evoked QT interval and the Legend (Medtronic) using vibration as indicators of metabolic demand, were compared for rate adaptive characteristics during different forms of exercise. While both showed improvements over previous generation pacemakers, they still show deficiencies in some aspects of rate modulation. Rhythmyx was slow to respond to changes in metabolic need and showed an "over-shoot" with increasing pacing rate on cessation of exercise. Legend was quick to adapt rate at beginning and end of exercise but showed a plateaus of rate modulation during the period of slowly increasing workload. Legend also showed only modest rate adaptation to changes in treadmill gradient and to bicycle ergometer exercise. Further developments in pacemaker technology are required if physiological rate adaptation to exercise is required.

Aged↗
PubMed1992

The expression of mouse tyrosinase in chick cells in vitro and in vivo when controlled by a constitutive promoter.

Virally introduced mouse tyrosinase expression was checked both in vitro and in vivo in chicken cells and tissues. The results indicate that a constitutive promoter is able to express mouse tyrosinase in a variety of cells and tissues both in vitro and in vivo. Tyrosinase expression is marked by pigment production in situ, which is visible at macroscopic as well as microscopic levels without the use of substrates. It is concluded that tyrosinase can be a valuable marker for tracking gene insertion since it is spontaneously expressed. The expression of tyrosinase in some cells and tissues has a detrimental effect, however, and should be controlled by tissue-specific promoters.

Animals↗
PubMed1992

Influence of cigarette smoking on the outcome of coronary care unit admissions with chest pain.

We studied the effect of current smoking habits in the period immediately before admission to hospital in 90 consecutive patients presenting with chest pain, 50 of whom were shown to have myocardial infarction. Urine cotinine/creatinine (cot/creat) ratio measured within 4 hours of admission was used as an objective marker of cigarette smoking in the preceding 18 hours. Fifty-seven patients had urine cot/creat ratios suggesting recent smoking, although four of these denied smoking. Patients with myocardial infarction had higher median cot/creat ratios (3.31 micrograms/mg, range 0-17.8) compared with patients with non-infarct chest pain (0.5 microgram/mg, range 0-37.2). Sixteen patients with cardiac rhythm disturbances following infarction had significantly higher cot/creat ratios than the 34 infarct patients without this complication (median and range 8.34 micrograms/mg; 0-17.8 V. 1.87 micrograms/mg; 0-16.4, P < 0.01). Tobacco use in the 24 hours before myocardial infarction may predispose to cardiac rhythm disturbance, irrespective of infarct size.

Adult↗
PubMed1992

Role of the ovary in the synthesis of placental protein-14.

Women with absent ovarian function provide an opportunity to investigate the ovarian contribution to secretion of placental proteins (PP), such as PP14, in early pregnancy. We present data on serum PP14 levels in 12 women (median age, 30.5 yr; range, 26-37 yr) with premature ovarian failure (POF) who conceived after ovum donation and embryo transfer with exogenous sex steroid support using transdermal (n = 5) or oral (n = 7) estradiol and vaginal (n = 8) or im (n = 4) progesterone. The women were closely monitored throughout early pregnancy, with measurement of serum levels of estradiol (E2), progesterone (P4), and PP14. Levels of E2 and P4 were entirely normal. Levels of PP14 were significantly subnormal (P = 0.008) in all 12 agonadal women compared with levels of PP14 in a control group of women with normal ovarian function between 6-12 weeks gestation. Basal and peak levels for subjects with absent ovarian function were 40 and 124 micrograms/L, respectively. For each week between 6-12 weeks of pregnancy, the mean serum levels of PP14 for women with normal ovarian function were between 706-940 micrograms/L. These observations support the concept that PP14 arises from the ovary in early pregnancy or that factors under the control of the maternal ovary are involved in its production by the endometrium.

Adult↗
PubMed1992

Stereotactic brachytherapy for malignant glioma using a relocatable frame.

Interstitial brachytherapy for recurrent gliomas normally necessitates the invasive application of a stereotactic frame by screw-fixation which must be kept on for several hours. The use of a relocatable stereotactic frame offers many advantages over conventional systems. We present our experience in 18 patients and verify that the frame used is accurate, comfortable, well tolerated and associated with no major disadvantages.

Adult↗
PubMed1992

Paget's disease of bone--current thinking and management.

OBJECTIVES: The objective of this article was to critically review the current knowledge on Paget's disease of bone, focusing primarily on possible etiologies and trends in management. Current courses of treatment are described, including calcitonin, diphosphonate and mithramycin therapy and the efficacy of each drug regime is analyzed. Finally, newer, more experimental pharmaceutical agents, such as gallium nitrate, are described. DATA SOURCES: Information was obtained from English language medical and scientific journals and medical/physiology text books. Index Medicus (1983-1989) and MEDLINE computerized data base were used. Paget's disease of bone, paramyxovirus, osteoclast, calcitonin and diphosphonate were the terms indexed directly. Key authors indexed included Rebel, Baste and Paget. Further information was obtained from the National Association for the Relief of Paget's Disease (England). CONCLUSIONS: Current research focuses primarily on histological and hybridization studies over the past 15 yr in favor of a slow virus as the causative agent in the disease, and the evidence supporting this is analyzed in some detail. In particular, the discovery of nuclear and cytoplasmic inclusion bodies within the osteoclasts of patients with Paget's disease and their similarity to respiratory syncytial virus and measles virus are discussed. Some form of environmental or physiological trigger may be involved, but the exact mechanism remains obscure. The current treatment of Paget's disease is based around the prevention of bone resorption using various diphosphonates and calcitonins, but many of these are associated with severe side effects. Newer pharmaceutical agents to control bone turnover, including gallium nitrate, have given promising results in preliminary medical trials.

Calcitonin↗