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Biomedical subjects

R Campbell

Publications and source records attributed to R Campbell.

At least 127 records · Page 7Linked to original sources
PubMed1994

Parental origin of transcription from the human GNAS1 gene.

Variation in the phenotypic expression of Albright's hereditary osteodystrophy (AHO) determined by the parent of transmission, suggests that the human Gs alpha gene (GNAS1), in which mutations occur in AHO, may be under imprinted control. GNAS1 is also known to map to a chromosomal region (20q13.11) showing syntenic homology with the imprinted mouse region 2E1-2H3. To establish if GNAS1 is indeed imprinted, we have examined the parental origin of GNAS1 transcription in human fetal tissues. Of 75 fetuses genotyped, at gestational ages ranging from 6 to 13 weeks, 13 heterozygous for a FokI polymorphism in exon 5 of GNAS1 were identified whose mothers were homozygous for one or other allele. RNA from up to 10 different tissues from each fetus was analysed by RT-PCR. In all cases expression from both parental alleles was shown by FokI digestion of RT-PCR products and quantification of the resulting fragments. No tissue specific pattern of expression was discerned in these experiments. If genomic imprinting regulates the expression of the human GNAS1 gene, our data suggest that the effect must either be subtle and quantitative, or be confined to a small subset of specialised hormone responsive cells within the target tissues.

Alleles↗
PubMed1994

Asystole and bradycardia during maxillofacial surgery.

A Chinese female undergoing maxillary osteotomy developed asystole when the maxillary tuberosity was cut. Surgery was stopped. After about 10 sec and before instituting cardiac massage, sinus rhythm and bradycardia ensued. Atropine was administered intravenously, resulting in an increase in heart rate. No further episodes of asystole or bradycardia were encountered.

Adult↗
PubMed1993

Amino acid sequence and thermostability of xylanase A from Schizophyllum commune.

The amino acid sequence (197 residues) of xylanase A from the fungus, Schizophyllum commune, was determined by automated analysis of peptides from proteolytic and acid cleavage. The sequence is similar to two Trichoderma xylanases (approximately 56% identical amino acids), but also shows at least 40% identities with xylanases from Bacillus subtilis, B. pumilus and B. circulans. The conserved regions of the enzyme contain only two glutamic acid residues which implicates their possible involvement in catalysis. The disulfide bond in xylanase A is not conserved in this family. In spite of this, the B. subtilis xylanase was found to be more thermostable than xylanase A.

Amino Acid Sequence↗
PubMed1993

Production and fluorescence-activated cell sorting of Escherichia coli expressing a functional antibody fragment on the external surface.

We have expressed a single chain Fv (scFv) antibody fragment, consisting of the variable heavy and variable light domains from two separate anti-digoxin monoclonal antibodies, on the external surface of Escherichia coli by fusing it to an Lpp-OmpA hybrid previously shown to direct heterologous proteins to the cell surface. This scFv fusion was expressed at a high level and was shown to bind the hapten with high affinity and specificity. Whole cell ELISAs, fluorescence microscopy, protease sensitivity, and flow cytometry all confirmed that the scFv was anchored on the outer membrane and was accessible on the surface. Utilizing fluorescence-activated cell sorting, we were able to specifically enrich scFv-producing cells from a 10(5)-fold excess of control cells in only two steps. The expression of antibody fragments on the surface of E. coli is being evaluated as an attractive method for the in vitro production and selection of useful antibody fragments.

Amino Acid Sequence↗
PubMed1993

Congenital anomalies and genetic syndromes in 173 cases of medulloblastoma.

One hundred seventy-three consecutive cases of medulloblastoma recorded in the Manchester Children's Tumour Registry from 1954 to 1989 were studied. After review of case notes, X-rays, and health surveys the clinical outcome and incidence of congenital anomaly was determined. A previously unreported association with Rubinstein Taybi syndrome was found. Evidence of a genetic syndrome or congenital anomaly was found in 6.4%. These figures provide further evidence of the higher-than-expected incidence of congenital abnormalities.

Adolescent↗
PubMed1993

Expressed emotion and glucose control in insulin-dependent diabetes mellitus.

To clarify the meaning of the expressed emotion construct by testing its generalizability beyond psychiatric disorders, the authors measured family expressed emotion and glucose control in 35 diabetic patients. The critical comments component of expressed emotion significantly predicted glucose control, suggesting that the expressed emotion construct is not specific to psychiatric patients.

Adolescent↗
PubMed1992

The neuropsychology of lipreading.

Lipreading presents a unique glimpse of the intersection of sensory processes with modular, cognitive ones. It presents speech to the eye in an automatic and natural way, whether performed silently or in conjunction with heard speech. It therefore allows us to examine closely claims concerning the relation between input modality and cognitive function. In this paper I consider some of the ways in which the investigation of single neuropsychological cases casts light on this; such cases show us that lipreading can dissociate from other aspects of face perception and recognition, and from auditory speech perception and reading, too. Furthermore, different cognitive components of lipreading itself can be inferred from dissociations on different lipreading tasks. This leads to closer consideration of the boundaries of the necessary cognitive (and possibly anatomical) structures that subserve these functions.

Brain↗
PubMed1992

Optic aphasia with spared action naming: a description and possible loci of impairment.

A brief functional description is given of an optic aphasic patient, A.G., who shows a pure and isolated deficit in naming visually presented objects on confrontation, but with sparing of visual action names. We show how some tasks related to imagery are compromised in this patient and speculate on possible functional site(s) of impairment in terms of the routes from perception to naming. We suggest why action naming may be spared in such cases.

Anomia↗
PubMed1992

Psychosocial and psychopathologic influences on management and control of insulin-dependent diabetes.

The objective of this research was to explore the relationship of psychosocial variables to management and control of insulin-dependent diabetes, as measured by a scale of reported behavioral adherence and by glycosylated hemoglobin, respectively. The method includes a relatively large sample (127 subjects) drawn from a clinic, a broad range of psychosocial variables (depression, anxiety, family process, health locus of control), and documented reliability and validity of psychosocial measurement (alpha coefficients ranging from .63 to .95). The results show that both anxiety and depression have weak positive correlations with blood sugar. Family process variables also are weakly correlated with blood sugar. The measure of behavioral adherence is moderately correlated with blood sugar. The life stage of the diabetic appears to affect these relationships markedly. The conclusion is that there is no broad strong association of psychosocial variables with blood sugar but that there may be subgroups of diabetics, especially adolescents with recent onset, for whom the relationships may be more powerful.

Adolescent↗
PubMed1992

Initial experience of laparoscopic cholecystectomy in a district hospital.

Fifty-five consecutive unselected patients were submitted for laparoscopic cholecystectomy, and the procedure completed laparoscopically in fifty cases. The outcome is presented with particular reference to the duration of surgery, postoperative pain and nausea, the length of hospital stay and the time taken to recover normal activities. This technique is shown to have major advantages over conventional gallbladder surgery for the majority of patients.

Adult↗
PubMed1991

Three-dimensional structure of murine anti-p-azophenylarsonate Fab 36-71. 1. X-ray crystallography, site-directed mutagenesis, and modeling of the complex with hapten.

The structure of the antigen-binding fragment (Fab) of an anti-p-azophenylarsonate monoclonal antibody, 36-71, bearing a major cross-reactive idiotype of A/J mice has been refined to an R factor of 24.8% at a resolution of 1.85 A. The previously solved partial structure of this Fab at a resolution of 2.9 A (Rose et al., 1990) was used as an initial model for refinement against the high-resolution data. The complex with hapten has been modeled by docking the small-molecule crystal structure of phenylarsonic acid into the structure of the native Fab on the basis of a low-resolution electron density map of the complex. In this model, residue Arg-96 in the light chain and residues Asn-35, Trp-47, and Ser-99 in the heavy chain contact the arsonate moiety of the hapten; an additional bond is found between the arsonate group and a tightly bound water molecule. The phenyl moiety of the hapten packs against two tyrosine side chains at positions 50 and 106 in the heavy chain. Residue Arg-96 in the light chain had been implicated as involved in hapten binding on the basis of previous experiments, and indeed, this residue appears to play a crucial role in this model. Experiments employing site-directed mutagenesis directly support this conclusion. The heavy-chain complementarity-determining regions have novel conformations not previously observed in immunoglobulins except for the recently solved anti-p-azophenylarsonate Fab R 19.9 (Lascombe et al., 1989).

Amino Acid Sequence↗
PubMed1991

A fifteen year follow-up of a case of developmental prosopagnosia.

The term developmental prosopagnosia refers to an impairment in the recognition of familiar faces which has been present from birth in the absence of neurological disease or birth complications. The first reported study was by McConachie (1976, Cortex, 12: 76-82) and we report here a fifteen year follow-up on this case (AB). Recently developed theoretical models postulating separate processes involved in face perception and recognition were used to guide the exploration of her functional deficit. Our investigations with AB showed that basic visuo-sensory functions (acuity, contrast sensitivity, colour, etc.) were largely intact. General face perception (e.g. distinguishing between a face and a "nonface") was relatively well preserved. Recognition of familiar faces was severely impaired and she also showed problems with other face processing tasks (e.g. analysis of facial expression) and in object recognition. In object recognition she made errors based on visual similarity, and she had problems identifying exemplars from categories with many visually similar items. In addition, she was very poor at identifying objects or silhouettes from an unusual viewpoint. We conclude that AB has always been poor at constructing an effective internal representation sufficient to permit recognition of items which are visually difficult to discriminate. Therefore, she may not have been able to acquire useable stored representations either, because this deficit has been present since birth. This functional account was supported by subsequent studies which demonstrated a complete absence of covert face recognition.

Agnosia↗
PubMed1991

Neuropsychological function in young children who have undergone liver transplantation.

Presented neuropsychological data from 20 patients between the ages of 4 and 9 years, who had undergone liver transplantation at least 12 months prior to study participation, and compared them to a control group of 20 children with cystic fibrosis. The liver transplant group showed deficits in VIQ, PIQ, visual-spatial and abstraction/reasoning skills, but not in alertness/concentration, motor, or sensory-perceptual functions. On motor and sensory-perceptual tests, no differences were found in direction of lateralization of deficits. Visual-spatial deficits found in this study sample are similar to those found in adults with end-stage liver disease and in a previous report of an overall older group of children following liver transplantation. However younger children have greater evidence of generalized impairment and VIQ deficits which have not been found in older groups. Findings are discussed in relation to possible etiology, location of brain damage, and clinical implications.

Brain Damage, Chronic↗