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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 217 records · Page 12Linked to original sources
PubMed1997

A case of the carbohydrate-deficient glycoprotein syndrome type 1 (CDGS type 1) with normal phosphomannomutase activity.

The carbohydrate-deficient glycoprotein syndrome (CDGS) is a group of disorders characterized biochemically by abnormal glycosylation of serum and cellular glycoproteins. It has been classified into four forms on the basis of the isoelectric focusing pattern of serum transferrin and difference in clinical presentation. A deficiency of phosphomannomutase (PMM) has been reported in most patients with type 1. Seven of our eight CDGS patients, classified clinically as type 1, were shown to have a deficiency of phosphomannomutase in their fibroblast or lymphoblastoid cells (0.04-0.2 nmol/min per mg, compared with a control range of 1.0-2.1 nmol/min per mg). The eighth patient, who had many clinical features of the severe neonatal form of CDGS type 1, but lacked definite signs of CNS and ocular involvement, had a normal phosphomannomutase activity in his fibroblasts. There were approximately equal amounts of disialo- and tetrasialotransferrin and only a trace amount of asialotransferrin in the serum and ascitic fluid of this patient. The disialo- and tetrasialotransferrin isoforms were purified by ion-exchange chromatography and analysed by SDS-PAGE. The disialotransferrin had a lower molecular mass than the tetrasialotransferrin, consistent with the absence of an N-linked glycan. The N-linked glycans released enzymically from both isoforms consisted exclusively of disialylated biantennary chains, suggesting that disialotransferrin results from underglycosylation, as in the PMM-deficient CDGS type 1 patients. It is concluded that the clinical and biochemical phenotype in CDGS type 1 can result from more than one basic defect.

Ascitic Fluid↗
PubMed1997

Recording sagittal condylar angles using a mandibular facebow.

The aim of this study was to determine the average sagittal condylar inclination angles of dentate subjects using a mandibular facebow with pencil tracing styli, to relate these angles to values assigned to articulators, and to assess the repeatability accuracy of drawing a tangent to a traced curve. The right and left sagittal condylar inclination angles of 103 subjects were recorded using a mandibular facebow with pencil tracing styli which marked a graph card during protrusive excursions. Tangents to the tracings were measured with a protractor allowing assessment of reproducibility. The mean left and right sagittal condylar inclination angles were 32 degrees and 31.5 degrees, respectively, with no significant differences (P= 0.609). Individual right and left measurements within each group showed significant differences (P = 0.0000). The mean of the tangents drawn through three sagittal condylar angle tracings by 10 operators was 33.3 degrees, and the mean of 10 tangents drawn through the same three tracings by one of the authors was 32.9 degrees, with no significant difference (P = 0.634). The average sagittal condylar inclination angles found in this study are in agreement with those reported in the literature. In fixed sagittal condylar angle articulators 30 degrees appear to be an appropriate setting. The reproducibility of this method of recording sagittal condylar inclination angles was found to be accurate for the individual operator and between operators.

Adolescent↗
PubMed1997

Total quality management in accredited New South Wales hospitals: a public/private comparison.

Analysis of data collected in a 1994-95 survey of accredited New South Wales hospitals examined the adoption of key elements of total quality management practice in the public and private sectors. In a number of areas of practice widely considered to be central to a hospital's total quality management efforts, there was no statistically significant difference between the two sectors. Where differences existed, total quality management practices more likely to be adopted by public hospitals were limited in their scope and likely to be explained by structural peculiarities. In contrast, private hospitals were more likely to adopt practices more critical to the successful implementation of total quality management.

Accreditation↗
PubMed1997

Analysis of 36-kilodalton protein (PapA) associated with the bacteriophage particle of Bartonella henselae.

A library of Bartonella henselae DNA was screened with antibody raised to the bacteriophage particle associated with this organism. A clone was isolated that expresses a 36-kD protein (termed PapA for particle-associated protein) when examined by immunoblot analysis using antibody raised to the particle. Southern blot hybridization indicates that the gene is present on the bacterial chromosome and packaged into the 14-kb particle-associated DNA. A papA-specific probe hybridized to multiple bands of B. henselae genomic DNA digested with several different restriction endonucleases. Thus, the gene is present in multiple copies on the genome or in different arrangements within a given population of B. henselae cells. The gene coding for PapA has been sequenced and codes for a 326-amino-acid protein with a deduced molecular weight of 36,161 daltons. The deduced protein shows 33.3% identity over a 108-amino-acid sequence with the P-min gene product of Escherichia coli. P-min is partially located within the invertible P region of the excisable element e14, found on the E. coli chromosome. Taken together, these results suggest that papA is present on a mobile genetic element of the B. henselae genome and is also packaged into the bacteriophage particle.

Amino Acid Sequence↗
PubMed1997

Airway reactivity to inhaled spasmogens 18-24 h after antigen-challenge in sensitized anaesthetized guinea-pigs.

The anaesthetized allergic guinea-pig was used to assess changes in airway reactivity to four different inhaled spasmogens: methacholine, 5-hydroxytryptamine (5-HT), histamine and the thromboxane A2 mimetic, 9,11-dideoxy-9 alpha,11 alpha-methano-epoxy-PGF2 alpha (U-46619). Reactivity was determined 18 to 24 h after challenge of ovalbumin-sensitized guinea-pigs with inhaled ovalbumin. This time coincides with the appearance of a late-phase bronchoconstriction in these animals. Sensitivity to the spasmogen was assessed from the concentration-response curve for the increase in pulmonary inflation pressure (PIP) in ovalbumin- and saline-challenged sensitized animals. When methacholine, 5-HT or histamine were the spasmogens there was no hyper-reactivity. The geometric mean EC50 values (i.e. the concentrations inducing half the maximum effect) obtained from the dose-response curves for methacholine (73 (42-129) and 94 (66-134) micrograms mL-1), 5-HT (1.5 (0.81-3.03) and 1.1 (0.51-2.24 micrograms mL-1) and histamine (39 (21-75) and 72 (32-162) micrograms mL-1) did not differ significantly (P > 0.05) between saline- and ovalbumin-challenged animals, respectively. However, when U-46619 was the spasmogen, ovalbumin-induced airway hyper-reactivity was observed as a leftwards shift of the concentration-response curve and the EC50 value for ovalbumin-challenged animals (8.1 (5.1-13) ng mL-1) was significantly (P < 0.05) less than the value for control animals (39 (21-75) ng mL-1). Our findings suggest that airway hyper-reactivity is not 'non-specific', but instead depends on the chosen spasmogen. The absence of hyper-reactivity with certain spasmogens was not a result of poor delivery, because all spasmogens caused a bronchoconstriction by the inhaled route. It was also not associated with the model because ozone has been shown to induce hyper-reactivity to inhaled methacholine and 5-HT. Because airway hyper-reactivity to both inhaled histamine and agonists at muscarinic receptors is regularly seen in man, the anaesthetized guinea-pig might not be the ideal model for assessing airway hyper-reactivity after antigen challenge and its modification by anti-asthma drugs.

Administration, Inhalation↗
PubMed1997

Retinoid antagonism of NF-IL6: insight into the mechanism of antiproliferative effects of retinoids in Kaposi's sarcoma.

All-trans-retinoic acid (RA) is active in the treatment of Kaposi's sarcoma (KS), and retinoids inhibit KS cell growth in vitro. To understand the mechanism of retinoid action in KS, we studied the expression of autocrine growth factors of KS cells after RA treatment. We demonstrate that RA and its synthetic analogs inhibit the proliferation of KS cells by inhibiting the mRNA and protein levels of interleukin-6 (IL-6), an autocrine growth factor for KS cells. We further demonstrate that nuclear retinoid receptors (RA receptors [RARs] and retinoid X receptors [RXRs]) inhibit IL-6 promoter action by antagonizing the enhancer action of NF-IL6, a basic domain leucine zipper transcription factor belonging to the family of CAAT enhancer binding proteins. Furthermore, RARs and RXRs do not bind in vitro to an NF-IL6 binding site. However, the secondary folded structure of the DNA binding domain of RAR and RXR is obligatory for inhibiting NF-IL6 activity. Thus, NF-IL6 is a potential therapeutic target for the treatment of KS. Finally, using receptor-selective synthetic retinoids, we demonstrate that NF-IL6 antagonism and transactivation are separable functions of RAR alpha, thus indicating that synthetic retinoids with properties of NF-IL6 antagonism but lacking transactivation capabilities can be synthesized. Such retinoids might increase therapeutic potential in KS.

CCAAT-Enhancer-Binding Proteins↗
PubMed1997

Comparing two methods of follow up in a multicentre randomised trial.

AIMS: To evaluate a parental questionnaire as a means of providing outcome measures for a multicentre randomised controlled trial of treatment for post-haemorrhagic ventricular dilatation. METHODS: The parents of 88 survivors were sent a questionnaire before a paediatric assessment at the age of 30 months. The parents' responses to individual questions taken mainly from the Griffiths' mental development scales and their perception of the child's ability to see and hear were compared with the paediatric findings. A model, based on the parents' responses to particular questions, allowed the categorisation of the children as normal, impaired, moderately or severely disabled; this was compared with similar categorisation based on the full paediatric assessment. RESULTS: Agreement on items concerning gross motor function ranged between 81 and 99%, concerning dressing between 77 and 80%, concerning feeding between 91 and 99%, and concerning language between 85 and 93%. Similar proportions of children were identified as disabled by the parents (60%) and by the paediatrician (66%). Of 29 children who had developmental quotients less than 70, parents identified 28 as disabled, 18 of them as severely disabled. They were not so good at identifying children with impairments without functional loss. CONCLUSIONS: Further work is required but there is sufficient encouragement from the results to pursue this methodology further for use in comparing groups in randomised trials.

Cerebrospinal Fluid Shunts↗
PubMed1997

Are outcome data regarding the survivors of neonatal care available from routine sources?

AIM: To determine whether existing information and surveillance systems can be used to provide follow up data on groups of infants at increased risk of disability--for example, the survivors of neonatal intensive care. METHODS: A survey was made of maternity, neonatal, and community child health information systems and surveillance programmes in the Trent Regional Health Authority. Children known to have received neonatal intensive care in Trent between 1 August 1992 and 31 July 1993, and a random sample of normal children in two health districts (data quality check) were included. A data linkage study was made to determine whether follow up information about a random sample of infants, known to be at increased risk of poor outcome, could be identified on community child health databases. Two widely accepted datasets (birth and 2 years) were used as standards for this exercise. The quality of data was audited. RESULTS: All clinical items of the birth minimum dataset were routinely recorded by at least one agency in each health district in Trent. Of the descriptive items, only the mother's age on leaving full time education was not collected. At 2 years, all clinical items were collected as part of the routine surveillance programme, but data were recorded using a system which severely limited interpretation. Data quality, in terms of the number of errors introduced at data entry, was very good with only 1.1% of the check items (4/368) incorrectly recorded. Only two districts had organised electronic transfer of data between maternity, neonatal, and community child health systems. The mother's NHS number, although available, was not routinely recorded by any system. The NHS number of the infant was routinely collected by six out of 12 community paediatric services. Data linkage was attempted in six districts with appropriate community child health databases. Just over 70% of the intensive care sample was successfully linked with follow up information on child health systems. CONCLUSIONS: The existing programmes for routine child surveillance could provide outcome data for high risk groups of infants, such as the survivors of neonatal intensive care. However, the present coding system used for data entry is inadequate. Furthermore, rates of identification, without the use of a unique identifier (NHS number) for each subject, are currently insufficient for monitoring health status in later life.

Child Health Services↗
PubMed1997

Paraplegia due to thoracic disc herniation.

Disc herniation at the thoracic the spine level is more common than generally thought. Localisation of pain may be vague and may erroneously point to cardiopulmonary, gastrointestinal, genito-urinary or even psychiatric disease. Magnetic resonance imaging is the investigation of choice, especially if spinal cord compression is suspected.

Adult↗
PubMed1997

Endothelial barrier dysfunction and p42 oxidation induced by TNF-alpha are mediated by nitric oxide.

We tested the hypothesis that nitric oxide (.NO) mediates tumor necrosis factor-alpha (TNF-alpha)-induced alterations in permeability and actin of pulmonary artery endothelial monolayers (PAEM). The permeability of PAEM was assessed by the clearance rate of albumin labeled with Evans blue dye. The PAEM Triton-soluble ("cytoskeletal-nonassociated") and -insoluble ("cytoskeletal-associated") lysates were analyzed by Western blot for actin and oxidized protein using polyclonal antibodies to the COOH terminus of actin and dinitrophenylhydrazone (DNP), respectively. PAEM were incubated with TNF-alpha (100 U/ml) for 4 h. Incubation of PAEM with TNF-alpha resulted in increases in 1) the .NO oxidation product nitrite (NO2-), 2) nitrotyrosine immunofluorescence, 3) the oxidation of p42 (tentatively identified as actin), and 4) permeability to Evans blue dye-albumin. The .NO synthase inhibitor aminoguanidine (100 microM) prevented the TNF-alpha-induced increase in NO2-, nitrotyrosine immunofluorescence, oxidized p42, and permeability. Coincubation with L-arginine (200 microM) or the .NO mimic spermine-NO (1 microM) prevented the ablation of the response to TNF-alpha by aminoguanidine. The data indicate that TNF-alpha-induced increases in endothelial permeability and oxidized protein are mediated by .NO in PAEM.

Actins↗
PubMed1997

Systemic and renal hemodynamic changes in the luteal phase of the menstrual cycle mimic early pregnancy.

Blood pressure decreases during early pregnancy in association with a decrease in peripheral vascular resistance and increases in renal plasma flow and glomerular filtration rate. These early changes suggest a potential association with corpora lutea function. To determine whether peripheral vasodilation occurs following ovulation, we studied 16 healthy women in the midfollicular and midluteal phases of the menstrual cycle. A significant decrease in mean arterial pressure in the midluteal phase of the cycle (midfollicular of 81.7 +/- 2.0 vs. midluteal of 75.4 +/- 2.3 mmHg, P < 0.005) was found in association with a decrease in systemic vascular resistance and an increase in cardiac output. Renal plasma flow and glomerular filtration rate increased. Plasma renin activity and aldosterone concentration increased significantly in the luteal phase accompanied by a decrease in atrial natriuretic peptide concentration. Serum sodium, chloride, and bicarbonate concentrations and osmolarity also declined significantly in the midluteal phase of the menstrual cycle. Urinary adenosine 3',5'-cyclic monophosphate (cAMP) excretion increased in the luteal compared with the follicular phase, whereas no changes in urinary cGMP or NO2/NO3 excretion were found. Thus peripheral vasodilation occurs in the luteal phase of the normal menstrual cycle in association with an increase in renal plasma flow and filtration. Activation of the renin-angiotensin-aldosterone axis is found in the luteal phase of the menstrual cycle. These changes are accompanied by an increase in urinary cAMP excretion indicating potential vasodilating mediators responsible for the observed hemodynamic changes.

Adult↗
PubMed1997

First-trimester growth patterns of aneuploid fetuses.

First-trimester growth restriction has been reported in certain aneuploid pregnancies. The purpose of this study was to evaluate this association further by comparing the crown-rump lengths (CRLs) and growth rates from 196 chromosomally abnormal fetuses with a control population of 1929 euploid fetuses. The mean CRLs and growth rates were significantly reduced (P < 0.05) in the groups of fetuses with trisomy 18 (n = 49), trisomy 13 (n = 19), and triploidy (n = 8). Using a fifth percentile cut-off, growth rate was a better discriminator than a single CRL in identifying fetuses affected with these aneuploidies. These growth parameters were not significantly reduced in fetuses with trisomy 21 (n = 92), sex chromosome trisomies (n = 20), or 45,X (n = 8). We conclude that fetal growth restriction associated with an underlying chromosome abnormality can occur as early as the first trimester. This phenomenon results from intrinsic fetal factors and not delayed ovulation. Such information is important to establish as first-trimester serum screening evolves.

Aneuploidy↗
PubMed1997

Crystal structures of heterochiral peptides. Part II. tert-Boc-valyl-D-alanyl-leucyl-alanyl methoxide.

Crystal structure of a heterochiral peptide, viz. Boc-Val1-D-Ala2-Leu3-Ala4-OMe with a D chiral residue in the second position of a sequence, has been determined [a = 40.44(1), b = 4.887(5), c = 15.381(5) A, beta = 109.6(1)degrees, space group C2, Z = 4, R = 0.11]. The peptide is in a parallel beta-sheet structure terminated by a distinct local bend. The structure is established by N-H...O as well as C alpha-H...O hydrogen bonds. The contiguous C alpha-H...O hydrogen bond observed in this structure is an unique observation.

Circular Dichroism↗
PubMed1997

Mosaicism: implications for postnatal outcome.

Mosaicism detected in the cytogenetic analysis of chorionic villi or cultured amniocytes can present a difficult and at times impossible interpretative dilemma. The finding may be indicative of a generalized fetal mosaicism. However, in the majority of cases, the abnormal cell line is representative of either an in-vitro event or a chromosomal error that is restricted to the extra-embryonic tissues. Advances in laboratory medicine have provided insight into the determination of which cases of true mosaicism have the greatest risk of being clinically significant with regard to the fetal genotype and phenotype. Despite the presence of a normal fetal karyotype, certain chromosomes involved in confined placental mosaiciam may increase the risk of poor perinatal outcome or predispose the fetus or neonate to the adverse effects of genetic imprinting owing to the development of uniparental disomy.

Amniocentesis↗