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Biomedical subjects

G Ball

Publications and source records attributed to G Ball.

At least 37 records · Page 2Linked to original sources
PubMed1996

Absence of continuous epitopes in the house dust mite major allergens Der p I from Dermatophagoides pteronyssinus and Der f I from Dermatophagoides farinae.

BACKGROUND: The house dust mite has been shown to be an important source of domestic allergens associated with immediate hypersensitivities. The Group I mite allergens Der p I from Dermatophagoides pteronyssinus and Der f I from D. farinae display extensive amino acid sequence homology and have similarities with cysteine protease enzymes. OBJECTIVE: The availability of the complete amino acid sequences for these allergens allowed us to search for the allergic determinants within these molecules. The aim of the present investigation was to identify any continuous IgE-binding epitopes within these amino acid sequences. We also sought to test the validity of previously reported Der p I peptide epitope sequences. METHODS: In order to identify any continuous IgE epitopes, the amino acid sequences of Der p I and Der f I were synthesized as decapeptides overlapping in sequence and coupled to plastic pins. The specific IgE-binding capacity of these peptides was assayed using an enzyme-linked biotin-streptavidin procedure and sera from patients known to be sensitive to these allergens. Previously reported Der p I peptide epitopes were synthesized as free peptides and tested for their ability to inhibit specific IgE binding to allergen extract discs. RESULTS: None of the pin-coupled Der p I or Der f I peptides was found by the continuous epitope mapping procedure to bind significantly to specific IgE in the sera of hypersensitive patients. The previously reported Der p I peptide epitopes did not inhibit specific IgE binding to mite extract discs. CONCLUSION: The specific IgE binding epitopes of the house dust mite allergens Der p I and Der f I are discontinuous in nature.

Allergens↗
PubMed1996

Laser Doppler vibrometer (LDV)--a new clinical tool for the otologist.

We describe a laser Doppler system (LDS) that can be used clinically for the measurement of tympanic membrane (TM), malleus and prosthesis head displacement in response to sound inputs of 80-to 100-dB sound-pressure level (SPL). It also has the potential for use in the operating room to perform measurements of prosthesis and stapes displacement. The information provided by such testing gives the otologist knowledge of TM and ossicular function that is unique in evaluating middle ear function; it should help select the best type of reconstruction in a given case and direct us toward new and better methods of TM and ossicular reconstruction. The results of umbo displacement measurements in 95 human ears are reported. Examples are provided of LDS measurements in representative ears and how they can be of help to the clinician. The potential of multisite TM-displacement testing is demonstrated in two temporal bones, including before and after partial ossicular replacement prosthesis (PORP) insertion.

Audiometry, Pure-Tone↗
PubMed1995

A direct sulfhydrylation pathway is used for methionine biosynthesis in Pseudomonas aeruginosa.

The relationship between genes and enzymes in the methionine biosynthetic pathway has been studied in Pseudomonas aeruginosa. The first step is catalysed by an O-succinylhomoserine synthase, the product of the metA gene mapped at 20 min on the chromosome. The second step is achieved by direct sulfhydrylation, involving the enzyme encoded by a metZ gene that we have identified and sequenced, located at 40 min. Thus Pseudomonas appears to be the only organism so far described that uses O-succinylhomoserine as substrate for a direct sulfhydrylation. As in yeast, the two transsulfuration pathways between cysteine and homocysteine, with cystathionine as an intermediate, probably exist in parallel in this organism.

Amino Acid Sequence↗
PubMed1994

Schizosaccharomyces pombe glycosylation mutant with altered cell surface properties.

Mutagenesis of Schizosaccharomyces pombe cells yielded a strain that made reduced amounts of invertase. A comparison of the O- and N-linked carbohydrate chains of the wild-type and mutant glycoproteins revealed that a single type of alpha 1-->2-linked mannose was missing in the mutant. Analysis of the wild-type galactomannoprotein showed that it contained a heterogeneous small "core" oligosaccharide fraction linked to asparagine with sugar compositions that ranged from Man9(GlcNAc)2- to Gal4Man10(GlcNAc)2-. The galactose units are in terminal positions of a Man10(GlcNAc)2- unit that is similar to the mannoprotein core of Saccharomyces cerevisiae. Attached to this core in a larger oligosaccharide fraction is an alpha 1-->6-linked polymannose chain that is substituted at position 2 with alpha-linked mannose and galactose. The O-linked sugars consist of mannose, alpha 1-->2-linked mannosylmannose and alpha 1-->2-linked galactosylmannose, along with small amounts of tri- and tetrasaccharides. The glycosylation mutant lacks alpha 1-->2-linked mannose on both the O-linked chains and the outer chain of the large N-linked chains, suggesting that it may be defective in regulation of an alpha 1,2-mannosyltransferase that adds mannose to glycoproteins in the Golgi.

Carbohydrate Conformation↗
PubMed1994

A major continuous allergenic epitope of bovine beta-lactoglobulin recognized by human IgE binding.

Hexapeptides of sequential overlapping sequences of beta-lactoglobulin (BLG) were used to probe serum from children with immediate-type cow milk allergy for IgE binding to continuous epitopes of BLG in an enhanced enzyme-linked immunosorbent assay (ELISA). Six regions of IgE binding were identified on the BLG molecule and these were synthesized as dodecapeptides. Inhibition of IgE binding to whole BLG was used to confirm the BLG-specific binding of IgE to each of the synthesized peptides. One of the peptides, peptide 4, showed inhibition in an IgE anti-BLG radioimmunoassay to all 16 sera tested. The patterns of inhibition with the native BLG molecule and peptide 4 were significantly correlated (P = 0.005), suggesting that this peptide contains a major continuous IgE binding epitope of BLG.

Allergens↗
PubMed1993

Natural history of cows' milk allergy in children: immunological outcome over 2 years.

In this investigation 98 children (median age 24 months) with cows' milk allergy (CMA) were studied over a median period of 2 years to see whether acquisition of clinical tolerance to cows' milk was associated with the changes in levels of IgG and IgE anti-cows' milk antibodies, and skin test reactivity to a cows' milk extract. Two groups of CMA patients were examined. The first were IgE sensitized and responded rapidly to small volumes of cows' milk with urticaria, and/or exacerbations of eczema, and/or wheeze, and/or vomiting (n = 69). The second, a late reacting group (n = 29) demonstrated coughing, diarrhoea, eczematoid rashes, and/or a combination of these which developed more than 20 hr after commencing normal volumes of cows' milk. Significant immunological changes were confined to the 69 IgE sensitized immediate-reacting-group of patients. Of these, there were 15 children who achieved clinical tolerance to cows' milk and they showed a significant fall in the levels of skin test reactivity to cows' milk over the study period (P < 0.01). In addition, these 15 children had lower serum IgE antibodies to cows' milk proteins both at the outset and the final follow-up compared with the 54 patients whose CMA persisted. No consistent change in the IgG antibody responses to cows' milk proteins was seen in either group of patients over the study period. The findings suggest patients with immediate type hypersensitivity to cows' milk proteins whose disease persists for more than 2 years have a more severe dysregulation of IgE synthesis to cows' milk proteins from the outset.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Xcp-mediated protein secretion in Pseudomonas aeruginosa: identification of two additional genes and evidence for regulation of xcp gene expression.

In Pseudomonas aeruginosa, several exoproteins synthesized with a signal sequence (elastase, lipase, phospholipases, alkaline phosphatase and exotoxin A) are secreted by a two-step mechanism. They first cross the inner membrane in a signal sequence-dependent way, and are further translocated across the outer membrane in a second step requiring secretion functions encoded by several xcp genes. Ten xcp genes have already been characterized (Bally et al., 1992a). In this study, two additional xcp genes, xcpP and xcpQ, are described. They are located in the 40 min region of the chromosome where they probably define an operon, divergent from the xcpR-Z operon previously characterized in this region. These two genes encode two proteins, XcpP and XcpQ, similar to PulC and PulD of the pul system of Klebsiella oxytoca. Moreover, the two divergent operons share a common regulation which is growth-phase dependent.

Amino Acid Sequence↗
PubMed1993

Gamma-interferon production in cow milk allergy.

The aim of this study was to develop an assay to assist in the diagnosis of delayed onset of adverse responses to cow milk in children, by measurement of gamma-interferon (GIFN) produced in vitro in response to beta-lactoglobulin-stimulated blood mononuclear cells. Diagnostic procedures identified 75 children with immediate reactions who had high total IgE and IgE-isotype responses to cow milk, 17 children who developed reactions after 24 h and had low total IgE and low IgE-isotype response to cow milk, and 59 milk-tolerant children. GIFN production was less in children with immediate reactions compared to those with late reactions (P < 0.009), or milk-tolerant children (P = 0.022). The results of this study suggest enhanced T-cell reactivity may be involved in the immuno-pathogenesis of non-immediate cow milk allergy, but GIFN production was not a clinically useful diagnostic test.

Age Factors↗
PubMed1993

Measurement of umbo vibration in human subjects--method and possible clinical applications.

A commercial laser doppler vibrometer (LDV) was used to evaluate umbo displacement at sound pressure levels of 60, 70, and 80 dB SPL at the tympanic membrane (TM) of six subjects. Thirty-five pure-tone test frequencies, five per octave, were tested from 140 to 19,433 Hz. A computer program (Tymptest) produced and controlled the tones as well as improved the signal-to-noise ratio of the LDV. The test took about an hour to perform and provided reproducible results in all subjects. In addition, measurement of umbo displacement using the same system was made in 15 fresh human temporal bones for comparison. Results in the humans revealed a relatively flat umbo displacement from 140 to 1000 Hz, with a gradually sloping roll-off of -8.25 dB per octave from 1000 to 7000 Hz. From 8000 to 14,000 Hz the roll-off increased to -12.5 dB per octave. At the mean resonant frequency of the middle ear, 1000 Hz, and an 80 dB SPL input, umbo displacement was 0.045 micron. The human temporal bones showed similar results. Possible future clinical applications of this measurement include the identification of ears with acoustically inefficient TMs (tin ears). By identifying and studying such ears we should be able to develop methods to improve their function and produce hearing threshold increases of 15 dB or more at key speech frequencies. In addition, analysis of umbo and TM vibration in reconstructed middle ears should help us achieve better postoperative hearing results.

Adolescent↗
PubMed1992

Protein secretion in Pseudomonas aeruginosa: characterization of seven xcp genes and processing of secretory apparatus components by prepilin peptidase.

The xcp genes are required for the secretion of most extracellular proteins by Pseudomonas aeruginosa. The products of these genes are essential for the transport of exoproteins across the outer membrane after they have reached the periplasm via a signal sequence-dependent pathway. To date, analysis of three xcp genes has suggested the conservation of this secretion pathway in many Gram-negative bacteria. Furthermore, the xcpA gene was shown to be identical to pilD, which encodes a peptidase involved in the processing of fimbrial (pili) subunits, suggesting a connection between pili biogenesis and protein secretion. Here the nucleotide sequences of seven other xcp genes, designated xcpR to -X, are presented. The N-termini of four of the encoded Xcp proteins display similarity to the N-termini of type IV pili, suggesting that XcpA is involved in the processing of these Xcp proteins. This could indeed be demonstrated in vivo. Furthermore, two other proteins, XcpR and XcpS, show similarity to the PilB and PilC proteins required for fimbriae assembly. Since XcpR and PilB display a canonical nucleotide-binding site, ATP hydrolysis may provide energy for both systems.

Amino Acid Sequence↗
PubMed1991

Cognitive-behavioral therapy for panic: an open study.

This paper reports results of an open prospective study of 26 patients who met DSM-III criteria for panic disorder or agoraphobia with panic attacks. Cognitive-behavioral treatment alone produced clinically and statistically significant improvement in panic symptoms, including both full-blown and limited symptom episodes. In addition, the treatment produced improvement in associated symptoms of phobic avoidance and generalized anxiety. This work provides further preliminary indication of the usefulness of cognitive-behavioral strategies as an alternative to medication in symptom-oriented treatments.

Adult↗
PubMed1991

Protein secretion in Pseudomonas aeruginosa: the xcpA gene encodes an integral inner membrane protein homologous to Klebsiella pneumoniae secretion function protein PulO.

xcp mutations have pleiotropic effects on the secretion of proteins in Pseudomonas aeruginosa PAO. The nucleotide sequence of a 1.2-kb DNA fragment that complements the xcp-1 mutation has been determined. Sequence analysis shows the xcpA gene product to be a 31.8-kDa polypeptide, with a highly hydrophobic character. This is consistent with a localization in the cytoplasmic membrane in P. aeruginosa, determined after specific expression of the xcpA gene under control of the T7 phi 10 promoter. A very strong homology was found between XcpA and PulO, a membrane protein required for pullulanase secretion in Klebsiella pneumoniae. This suggests the existence of a signal sequence-dependent secretion process common to these two unrelated gram-negative bacteria.

Amino Acid Sequence↗
PubMed1991

Vulnerability to sodium lactate in panic disorder patients given cognitive-behavioral therapy.

Six patients with panic disorder who had panicked during sodium lactate infusion were given cognitive-behavioral treatment for 12-24 weeks. After treatment they underwent another lactate infusion, and four patients were rates as having no panic, suggesting that reduced vulnerability to lactate accompanies remission of panic. Controlled trials of cognitive-behavioral therapy and use of lactate infusion as a measure of remission are recommended.

Adolescent↗
PubMed1990

Protein secretion in gram-negative bacteria: transport across the outer membrane involves common mechanisms in different bacteria.

The xcp genes are required for protein secretion by Pseudomonas aeruginosa. They are involved in the second step of the process, i.e. the translocation across the outer membrane, after the exoproteins have reached the periplasm in a signal peptide dependent fashion. The nucleotide sequence of a 2.5 kb DNA fragment containing xcp genes showed at least two complete open reading frames, potentially encoding proteins with molecular weights of 41 and 19 kd. Products with these apparent molecular weights were identified after expression of the DNA fragment in vitro and in vivo. Subcloning and complementation experiments showed that both proteins are required for secretion. The two products are located in the inner membrane and share highly significant homologies with the PulL and PulM proteins which are required for the specific secretion of pullulanase in Klebsiella pneumoniae. These homologies reveal the existence of a common mechanism for protein secretion in Pseudomonas aeruginosa and Klebsiella pneumoniae.

Amino Acid Sequence↗
PubMed1989

Recovery from milk allergy in early childhood: antibody studies.

We assessed the relationships of clinical symptoms and serum antibody levels during follow-up of 47 patients, aged 3 to 66 months, who were shown by formal milk challenge to have cow milk allergy. Three groups of patients were identified. Group 1 patients (n = 15) were sensitized to IgE and responded rapidly to small volumes of milk with urticaria, an exacerbation of eczema, wheeze, or vomiting. In the second group (n = 24), symptoms of milk enteropathy (vomiting and diarrhea) developed between 1 and 20 hours after milk ingestion. In the group 3 patients (n = 8), coughing, diarrhea, eczematoid rashes, or a combination of these developed more than 20 hours after normal volumes of milk were given. Serum levels of IgG, IgA, IgM, and IgE and of milk-specific anti-cow milk antibodies of these isotypes were measured initially and then at a median follow-up time of 16 months (range 6 to 39 months). In this investigation, changes in these immunologic measures during the study period were related to whether or not clinical tolerance to cow milk was achieved. At follow-up, six patients from group 1, ten from group 2, and two from group 3 were milk tolerant. No consistent change in any of the immunologic measurements was associated with remission of the disease. These findings raise the question of whether acquisition of clinical tolerance to cow milk in cow milk allergy can be attributed solely to immunologic events.

Animals↗
PubMed1988

Systemic lymphoproliferative responses to rotavirus.

In comparison with healthy adults, elderly patients and patients who had received renal transplants had significantly lower lymphoproliferative responses to rotavirus (P = 0.04, P = 0.002, respectively) and phytohaemagglutinin (P = 0.001). However, following acute rotavirus infection, elderly persons mounted good lymphoproliferative and specific antibody responses to rotavirus. No lymphoproliferative response or specific antibody to rotavirus was detected in a child with cartilage hair hypoplasia. In cord blood samples, specific antibodies were detected in the absence of a lymphoproliferative response to rotavirus. Increases in lymphoproliferative responses as well as specific antibodies were not detected in immune adult recipients of a human rotavirus vaccine (RIT 4375), but a recipient of a bovine vaccine (RIT 4237) had an increase in lymphoproliferative response to rotavirus between 13 and 28 days postvaccination. Stimulation indices for both rotavirus and phytohaemagglutinin within the vaccine groups were comparable to the healthy laboratory personnel group.

Adult↗