Biomedical subjects

S Robb

Publications and source records attributed to S Robb.

17 recordsLinked to original sources

PubMed1997

Early onset autosomal dominant myopathy with rigidity of the spine: a possible role for laminin beta 1?

We describe 17 individuals from seven families with a slowly progressive, early onset, autosomal dominant myopathy with proximal muscle weakness, calf hypertrophy, contractures, spinal rigidity and, in five of the adult cases, a cardiac conduction defect. A deficiency of the laminin beta 1 chain of the skeletal muscle fibres was found in the older individuals of these families, but not the younger members. Other laminin chains, dystrophin and the dystrophin-associated glycoproteins were normal. The age-related deficiency of the laminin beta 1 is restricted to the skeletal muscle fibres and not the vascular tissue, suggesting that this may be a secondary phenomenon. These findings suggest that a laminin or a laminin-binding protein is implicated in some forms of dominant limb girdle myopathies.

Adolescent↗

PubMed1996

PEHO or PEHO-like syndrome?

PEHO syndrome is a rare progressive infantile encephalopathy, with variable age of onset of hypotonia, convulsions, mental retardation, oedema, and optic atrophy. Neuroimaging shows cerebellar and brainstem atrophy in most instances. A PEHO-like syndrome has been described in which those affected do not have the typical changes on neuroimaging. We report four new cases, two isolated cases and two sisters, who might be part of the PEHO-like syndrome.

Abnormalities, Multiple↗

PubMed1995

Agonist-specific coupling of G-protein-coupled receptors to second-messenger systems.

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Amino Acid Sequence↗

PubMed1994

Agonist-specific coupling of a cloned Drosophila octopamine/tyramine receptor to multiple second messenger systems.

A cloned seven transmembrane-spanning Drosophila octopamine/tyramine receptor, permanently expressed in a Chinese hamster ovary cell line, both inhibits adenylate cyclase activity and leads to the elevation of intracellular Ca2+ levels by separate G-protein-coupled pathways. Agonists of this receptor (octopamine and tyramine), differing by only a single hydroxyl group in their side chain, may be capable of differentially coupling it to different second messenger systems. Thus, a single receptor may have a different pharmacological profile depending on which second messenger system is used to assay its efficacy.

Animals↗

PubMed1993

Octopamine receptor subtypes and their modes of action.

Octopamine receptor subclasses were first proposed to explain differences in the pharmacological profiles of a range of physiological responses to octopamine obtained in the extensor-tibiae neuromuscular preparation of the locust. Thus, OCTOPAMINE1 receptors which inhibit an endogenous myogenic rhythm, increase intracellular calcium levels. Also OCTOPAMINE2 receptors which modulate neuromuscular transmission in this preparation, increase the level of adenylate cyclase activity. The current status of this classification is reviewed by examining the pharmacology of responses to octopamine in a range of preparations. It is concluded that the distinction between OCTOPAMINE1 and OCTOPAMINE2 receptor types is still valid, but that OCTOPAMINE2 receptors exhibit some tissue specific variations. Studies on a cloned Drosophila octopamine/tyramine (phentolamine) receptor are discussed and illustrate many of the difficulties presently encountered in making a definitive classification of octopamine receptors. These include the possibilities that single receptors may activate multiple second messenger systems and that different agonists may differentially couple the same receptor to different second messenger systems.

Animals↗

PubMed1993

Congenital sensory neuropathy in association with ichthyosis and anterior chamber cleavage syndrome.

Two patients with a congenital neuropathy are described. Both had atypical features including: ichthyosis and a mild anterior chamber cleavage syndrome. Both had severely reduced, or absent, sensation for light touch, vibration, position and temperature. Pain sensation was mildly reduced. There was some evidence of motor involvement but this was relatively minor compared with the sensory involvement. Nerve action potentials were small or absent and sural nerve biopsies showed almost complete absence of myelinated nerve fibres with multiple bundles of abnormally arranged axons and Schwann cell processes. These patients appear to have an undescribed syndrome in which the large sensory neurons and the anterior chamber of the eye did not develop properly. This may reflect a failure of migration, differentiation or proliferation of neural crest cells.

Action Potentials↗

PubMed1992

Development of intelligence and memory in children with hemiplegic cerebral palsy. The deleterious consequences of early seizures.

Although substantial data exist regarding the consequences of early lateralized cerebral lesions on intelligence and language ability, little is known about the development of other cognitive functions after such lesions. We examined the development of both verbal and nonverbal memory in 82 hemiplegic children, grouped according to hemispheric side of injury and presence or absence of seizure disorder. The control group consisted of 41 age-matched normal children, most of them siblings of the patients. Measures were obtained of intelligence and of immediate and delayed recall for prose passages, word paired associates and geometric designs. Electrophysiological and neuroradiological measures were available for a majority of the patients. The scores of the hemiplegic children on the IQ and memory tests did not exhibit the pattern seen in brain-damaged adults, in that the children's deficits showed no relation to hemispheric side of damage. Indeed, early cerebral damage to either hemisphere, even if extensive, resulted in relatively few and mild deficits if the damage was unaccompanied by seizure activity. By contrast, early lateralized lesions that were accompanied by a seizure disorder resulted in both a high incidence and degree of deficit that was unrelated to lesion side.

Cerebral Palsy↗

PubMed1991

Uniparental paternal disomy in Angelman's syndrome.

Angelman's syndrome and Prader-Willi syndrome are both causes of mental retardation with recognisable, but quite different, clinical phenotypes. Both are associated with deletions of chromosome 15q11-13, of maternal origin in Angelman's and paternal in Prader-Willi. Prader-Willi can arise by inheritance of two chromosomes 15 from the mother and none from the father (uniparental maternal disomy). In 2 patients with Angelman's syndrome we found evidence of uniparental paternal disomy. The phenotypic effects of maternal and paternal disomy of chromosome 15 are very different and inheritance of two normal 15s from one parent does not lead to normal development--strong evidence in man for genomic imprinting, in which the same gene has different effects dependent upon its parental origin.

Alleles↗

PubMed1990

FMRFamide-like peptides in the locust: distribution, partial characterization and bioactivity.

The quantitative distribution of FMRFamide-like peptides in the nervous system and in their putative target sites in the locust Schistocerca gregaria is described using radioimmunoassay techniques. The nature of the immunoreactive material has been characterized by high-pressure liquid chromatography. At least six peaks of FMRFamide-like immunoreactivity can be separated in extracts of locust nervous tissue. The relative proportions of these peaks vary from tissue to tissue, suggesting a differential expression of FMRFamide-like peptides in different parts of the locust nervous system. The bioactivity of the endogenous FMRFamide-like peptides has been assessed on the extensor tibiae neuromuscular preparation and on the locust heart. The results suggest that FMRFamide-like peptides in the locust function both as circulating neurohormones and as locally released neuromodulators or neurotransmitters.

Animals↗

PubMed1989

Isolation, primary structure and bioactivity of schistoflrf-amide, a FMRF-amide-like neuropeptide from the locust, Schistocerca gregaria.

We have isolated a neuropeptide, related to the Phe-Met-Arg-Phe-NH2 family, from the thoracic nervous system of the locust, Schistocerca gregaria, using a purification system based on the radioimmunoassay of high pressure liquid chromatography fractions. The primary sequence of this locust peptide is Pro-Asp-Val-Asp-His-Val-Phe-Leu-Arg-Phe-NH2. The bioactivities of the native and synthetic neuropeptide are identical in both the locust heart and hindleg extensor-tibiae muscle bioassays.

Amino Acid Sequence↗

PubMed1980