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Biomedical subjects

M G Harrington

Publications and source records attributed to M G Harrington.

At least 19 recordsLinked to original sources
PubMed1992

Complexity of sea urchin embryo nuclear proteins that contain basic domains.

We describe a quantitative two-dimensional gel electrophoretic analysis of nuclear extract from 24-hr sea urchin embryos. The extract was fractionated by using a weak cation-exchange resin, and eight known DNA-binding proteins were shown to be entirely included in a salt eluate that releases proteins containing basic domains. This fraction and a lower-salt fraction containing the majority of the protein species were mapped two-dimensionally by using new algorithms that permit reproducible spot identification, storage of intensity and map-position data, and subtractive comparison of one pattern with respect to another. By reference to a previously characterized DNA-binding factor, spot intensity could be interpreted in terms of the number of molecules per embryo nucleus. A map was constructed displaying all nuclear proteins containing basic domains that are present within the concentration range per nucleus of a set of known DNA-binding factors of the sea urchin embryo. The map includes 265 spots that fulfill both of these criteria, probably representing about 100 different protein species.

Animals↗
PubMed1990

Noradrenergic control of the synthesis of two rat pineal proteins.

Pineal physiology is controlled by norepinephrine released from sympathetic nerves terminating in the gland. In the present study, the effect of norepinephrine on the labelling of specific proteins was investigated by incubating glands with [35S]methionine and then resolving the proteins by two-dimensional polyacrylamide gel electrophoresis; the patterns were analyzed by computer-assisted image analysis. The most prominent effects of norepinephrine were distinct and consistent increases in the labelling of two proteins (37 kDa, pI = 6.0, 50 kDa, pI = 6.0), designated adrenergically induced protein (AIP 37/6 and AIP 50/6). In both cases, norepinephrine was effective at low concentrations (EC50 = 10 nM). Pharmacological studies indicated that the effects of norepinephrine on both proteins involved a beta-adrenergic receptor, and that cyclic AMP was the second messenger. Pulse-chase labelling experiments revealed that these effects of norepinephrine did not involve post-translational modification of previously labelled precursor proteins, but depended upon de novo synthesis of protein. An inhibitor of mRNA synthesis, actinomycin-D, was found to block the effect of norepinephrine on AIP 50/6 but not on AIP 37/6, suggesting that norepinephrine acted on AIP 50/6 via a transcriptional mechanism and on AIP 37/6 via a translational mechanism. These in vitro studies were extended into in vivo investigations by measuring silver-stained AIP 37/6 in the two-dimensional gels. Changes in the amount of AIP 37/6 in pineal glands were studied in response to treatments which block the adrenergic stimulation of the gland, including exposure to constant lighting or removal of the superior cervical ganglia. Both treatments reduced AIP 37/6 by 50-75% in 8 weeks. These observations, together with those from in vitro studies, suggest that the amount of AIP 37/6 in the pineal gland is regulated by norepinephrine; and further, that norepinephrine acts through a beta-adrenergic-cyclic AMP mechanism to control AIP 37/6 synthesis at a translational level.

Adrenergic Fibers↗
PubMed1990

Pre-mortem diagnosis of Creutzfeldt-Jakob disease by detection of abnormal cerebrospinal fluid proteins.

Creutzfeldt-Jakob disease (CJD) may be difficult to diagnose early or when it has an atypical presentation. We describe two patients with progressive dementia in whom the results of diagnostic brain biopsies were unhelpful. Spinal fluid from these patients, analyzed by two-dimensional electrophoresis, contained two abnormal proteins (Nos. 130 and 131, with relative molecular masses of 26,000 and 29,000 daltons and isoelectric points of 5.2 and 5.1). These findings suggested a provisional diagnosis of Creutzfeldt-Jakob disease, which was confirmed in both patients at autopsy. Detection of these abnormal cerebrospinal fluid proteins appears to be a valuable laboratory adjunct in evaluating patients with an unexplained progressive dementia.

Aged↗
PubMed1988

Cerebrospinal fluid protein analysis in diseases of the nervous system.

Electrophoretic studies of human CSF proteins from patients with diseases of the NS are reviewed. Various 1-DE methods are of similar value in identifying the non-specific OBs, which are helpful in the diagnosis of MS and recurrent GBS. In early and subclinical MS, OBs are of prognostic value, with IEF gels having the greater resolution. Silver-stained 2-DE gels provide the equivalent information to the OBs on 1-DE gels, with even greater sensitivity, and yield additional disease-associated protein data. Two proteins have proven to have diagnostic value in CJD and other changes that are still being evaluated have been identified in Parkinson's disease, GBS, Alzheimer's disease, schizophrenia and Herpes simplex encephalitis. The vastly improved CSF protein information obtained with silver-stained 2-DE gels heralds both a change from the relatively limited applications with 1-DE methods and also the need to adopt this approach in the routine clinical laboratory.

Animals↗
PubMed1988

Methods for increasing the resolution of two-dimensional protein electrophoresis.

A two-dimensional gel elctrophoresis protocol has been developed which provides for a 1.5-to 3-fold increase in the resolution of proteins compared to other frequently used methods. The major variations from previous protocols include increased pore size in the isoelectric focusing gels; cholamidopropyldimethylhydroxypropanesulfonate, a zwitterionic detergent, replaces most of the Nonidet P-40, a nonionic detergent, in the isoelectric focusing gels; no equilibration step is employed between the first and second dimensional separation. The use of a stacking gel in the second dimension has been eliminated; a more efficient and evenly distributed cooling system has been designed for the molecular mass separation, allowing faster migration with higher current. Finally, the crosslinker diacrylylpiperazine is employed which improves protein separation and detection with ammoniacal silver staining. Silver-stained two-dimensional gel electrophoretograms of human plasma and hamster brain tissues and autoradiographs of rat liver cells are compared to the results obtained from previous methods.

Animals↗
PubMed1988

The first year of a geriatric-orthopaedic liaison service: an alternative to 'orthogeriatric' units?

The use of orthopaedic beds by large numbers of elderly patients with multiple pathology will increase and already exceeds the provision of orthopaedic-geriatric rehabilitation units. A cross-specialty multidisciplinary ward round improved the quality of care of orthopaedic patients without requiring expenditure on equipment, facilities or staff, and abolished the need to transfer patients to geriatric beds for rehabilitation, this being achieved on the orthopaedic unit. The liaison service provided excellent medical training in acute and rehabilitative aspects of geriatric medicine, enhanced the role of other disciplines in the care of the elderly orthopaedic patient and facilitated communication between departments.

Geriatrics↗
PubMed1988

Use of two-dimensional electrophoretic protein maps in studies of schizophrenia.

High resolution two-dimensional electrophoresis (2DE) and silver staining have provided a technology capable of mapping large numbers of proteins from tissues and body fluids. Further identification of individual proteins that have been visualized by 2DE includes their characterization by immunodetection methods and by obtaining amino acid sequences from which antibody and synthetic oligonucleotide probes can be synthesized. As many as 3,500 individual proteins may be observed on a single electrophoretogram. This capacity to observe gene products permits the scanning of as many as 3.5 megabases of the protein coding regions of the genome for mutational events on each gel, and may also provide evidence concerning abnormal rates of protein synthesis or degradation, posttranslational modifications, and the presence of gene products of exogenous origin. The application of this technology has revealed a pair of abnormal cerebrospinal fluid (CSF) proteins (40KD) in one-third of schizophrenic patients screened. These abnormal proteins have never been observed in CSF from normal controls. However, they have been detected in some diseases of the central nervous system that may be of viral origin. Structural studies on these proteins should provide evidence of their origin, while ongoing studies of brain proteins may provide additional clues about this disease.

Cerebrospinal Fluid Proteins↗