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J Chapman

Publications and source records attributed to J Chapman.

At least 325 records · Page 18Linked to original sources
PubMed1991

Monoclonal antibodies to the heavy neurofilament subunit (NF-H) of Torpedo cholinergic neurons.

Previous studies from our laboratory suggest that Alzheimer's disease sera contain a repertoire of antibodies to the heavy neurofilament subunit (NF-H) and that a subpopulation of these antibodies bind specifically to epitopes highly enriched in NF-H isolated from the purely cholinergic electromotor neurons of Torpedo. In the present study, we prepared and characterized monoclonal antibodies (MAbs) that bind to epitopes specifically enriched in Torpedo cholinergic neurons. This was performed by a differential enzyme-linked immunosorbent assay (ELISA) in which MAbs were selected that bind to epitopes much more abundant in the NF-H protein of Torpedo cholinergic neurons than in NF-H from the chemically heterogeneous Torpedo spinal cord. This yielded four MAbs, three of which (TC4, TC8, and TC21) were found to be specific to NF-H and one (TC15) that reacts with both NF-H and the medium-size neurofilament subunit NF-M. Dephosphorylation abolishes the binding of MAbs TC4 and TC15 to Torpedo cholinergic NF-H, partially reduces that of MAb TC21 and has no effect on the binding of MAb TC8. This suggests that the antigenic sites specific to Torpedo cholinergic NF-H contain phosphorylated as well as non phosphorylated epitopes. All the MAbs cross-react with rat brain NF-H.

Animals↗
PubMed1991

Creutzfeldt-Jacob disease associated with the PRNP codon 200Lys mutation: an analysis of 45 families.

200Lys mutation in the human PRNP coding region has been identified in 45 of the 55 CJD-affected families thus far presented to our NIH laboratory. These codon 200Lys families have a total of 87 patients, and originate from 7 different countries: Slovakia, Poland, Germany, Tunisia, Greece, Libya, and Chile. Forty-seven patients were neuropathologically verified, and brain tissue from 14 patients transmitted disease to experimental primates. The mutation was found by direct sequencing in 4 patients, and it was detected by restriction endonuclease analysis with BsmA 1 and/or the single nucleotide extension reaction in 36 other patients and 45 of 109 first degree relatives (1 parent, 14 siblings, and 30 children). The mutation is associated with all known geographical clusters of CJD (Slovakia, Libyan Jews, Chile) in which the annual mortality rate is tens or hundreds of times higher than the world average of 1 per million. All patients originating from the cluster areas carried the mutation, but it was seen in only 1 of 103 unrelated control individuals from the same areas, and in none of 102 controls from other areas, indicating a strong association between the mutation and disease. The penetrance of the mutation was estimated to be 0.56. Branches of some families migrating from cluster areas to other countries continue to have CJD over several generations, suggesting that CJD in these families is a genetic disorder, in which the 200Lys mutation is responsible for the disease.

Africa↗
PubMed1991

Anti-neuronal antibodies similar to those found in Alzheimer's disease induce memory dysfunction in rats.

Although the etiology and pathogenesis of the cholinergic degeneration in Alzheimer's disease are not known, several reports implicate immunological mechanisms. Recently we have shown that sera of Alzheimer's disease patients contain antibodies which bind specifically to the heavy molecular weight neurofilament protein of Torpedo cholinergic neurons. In the present study we investigated the possibility that such antibodies play a role in neuronal degeneration by examining the behavioral and cellular effects of immunizing rats with the heavy neurofilament protein of Torpedo cholinergic neurons. The immunized rats developed antibodies which were specific to the heavy neurofilament protein of Torpedo cholinergic neurons and which cross-reacted with rat brain neurofilaments. Immunohistochemical studies revealed the accumulation of antibodies in the perikarya and neurites of neurons in the septum and hippocampus of the cholinergic neurofilament immunized rats and in white matter tracts in their forebrains. No such staining was seen in adjuvant immunized control rats. Behavioral tests revealed that rats immunized with the heavy cholinergic neurofilament protein performed significantly worse than controls in a T-maze alternation test and that their performance deteriorated profoundly after the introduction of a 20-s delay in the paradigm, indicating a deficit in short term memory. In contrast, both groups performed similarly in a T-maze discrimination test, indicating that long term reference memory was not affected by immunization with the heavy cholinergic neurofilament protein. Further experiments revealed that the rats immunized with the heavy cholinergic neurofilament protein were also deficient in a reversal of choice paradigm in a position discrimination test.(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMed1991

A mutation in the prion protein gene in Creutzfeldt-Jakob disease in Jewish patients of Libyan, Greek, and Tunisian origin.

A modified host protein encoded by the gene specifying the scrapie amyloid precursor is critically involved in the pathogenesis of transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker's syndrome, and Kuru. A mutation in the open reading frame of this gene was recently described in a cluster of patients with CJD in Slovakia. This mutation at codon 200 changes glutamic acid coded by GAG to lysine coded by AAG. We examined the prevalence of this mutation in the cluster of patients with CJD among Sephardic Jews of Libyan descent in Israel. A polymerase chain reaction was used to amplify the open reading frame of the prion protein gene from DNA extracted from frozen brain tissue of five Israeli residents (four of Libyan and one of Greek origin) and two familial cases in Jews born in Greece and Tunisia who later emigrated to France. The existence of the codon 200 mutation was detected by digestion of the open reading frame fragments with the BsmA1 restriction enzyme. All patients had the same codon 200 mutation. These findings implicate this mutation in the high prevalence of CJD among Libyan and Sephardic Jews from other Mediterranean countries.

Creutzfeldt-Jakob Syndrome↗
PubMed1991

Characterization of an experimental autoimmune dementia model in the rat.

Alzheimer's disease (AD) and other age-related cognitive deficits are associated with autoimmune phenomena. We recently showed that AD sera contain IgG that binds specifically to the heavy molecular weight neurofilament protein (NF-H) of Torpedo cholinergic neurons. We presently examined the behavioral effects of the induction of such antibodies in rats by prolonged immunization with Torpedo cholinergic NF-H. Immunohistochemical studies revealed the accumulation of IgG in the septum and hippocampus and in white matter tracts of these rats. T-maze alternation and discrimination tests revealed that immunization impaired the short-term working memory of the rats but had no effect on their reference memory. This impairment in short-term memory was reversed by treatment with the acetylcholinesterase inhibitor physostigmine. This animal model, termed experimental autoimmune dementia (EAD), may replicate immunologically induced pathogenic processes in AD.

Alzheimer Disease↗
PubMed1991

Reported measles immunisation and serological immunity in children attending general practitioners.

To determine the feasibility of serological testing for measles immunity in children attending general practitioners and to assess the validity of establishing immune status by reported immunisation history compared with serology, a cross-sectional descriptive study was conducted in general practices in the Illawarra area south of Sydney, New South Wales. Participants were 234 children under 15 years attending general practitioners. 87 per cent of children were reported to have been immunised against measles, but 46 per cent of these children were seronegative for measles antibody using an ELISA test on finger-prick blood. This could not be explained by inaccurate reporting of immunisation. No causes other than failure to seroconvert or inadequate specificity of the test on the blood samples were evident. Failure to seroconvert as a result of inadequate adherence to cold chain requirements is a possibility that needs further investigation. The results further question whether a single vaccination is adequate to achieve the public health aims of measles immunisation programs.

Adolescent↗
PubMed1991

Genetic and environmental factors determining the development of Creutzfeldt-Jakob disease in Libyan Jews.

The cluster of Creutzfeldt-Jakob disease (CJD) among Jews of Libyan origin is one of the largest in the world. A number of hypotheses have been proposed to account for this cluster, the most prevalent but unsubstantiated hypothesis being that a transmissible agent was ingested in the form of scrapie-infected sheep brains. It has, however, been shown that a modified host protein encoded by the gene specifying the scrapie amyloid precursor is critically involved in the pathogenesis of transmissible spongiform encephalopathies such as CJD, Gerstmann-Strüssler-Scheinker syndrome and Kuru. A mutation at codon 200 in the open reading frame of this gene has recently been linked to a cluster of CJD patients in Slovakia. We examined the prevalence of this mutation among CJD patients of Libyan descent in Israel. All patients were found to have the same codon 200 mutation. These findings implicate this mutation in the high prevalence of CJD among Libyan Jews and Sephardic Jews from other Mediterranean countries.

Cluster Analysis↗
PubMed1991

Increased urinary transferrin excretion in exercising normoalbuminuric insulin-dependent diabetic patients.

The median rate of urinary transferrin excretion is greatly increased by exercise in subjects with uncomplicated type 1 (insulin-dependent) diabetes. This increase is proportionally far greater than that seen in urinary albumin excretion rate after the same exercise. Non-diabetic control subjects showed no rise in urinary transferrin excretion rate following exercise. N-acetyl-beta-D-glucosaminidase excretion rate was higher in diabetic than control groups but did not rise with exercise. Our results suggest that patients with apparently uncomplicated diabetes have abnormal renal function. In this group an elevated urinary transferrin excretion rate appears to be a more sensitive indicator of altered renal function than is elevated albumin excretion rate. The mechanism underlying exercise-induced urinary loss of transferrin remains to be elucidated.

Acetylglucosaminidase↗
PubMed1991

Abnormal blood pressure response to exercise in normoalbuminuric insulin dependent diabetic patients.

Eight male normoproteinuric Type I (insulin dependent) diabetic patients and eight age- and sex-matched non-diabetic control subjects were studied for their response to exercise. Systolic blood pressure showed an exaggerated response to exercise in the diabetic group (median 123, range 98-151 mmHg, pre-exercise vs. 187, 163-217 mmHg, immediately post exercise P less than 0.01) compared to the control group (median 112 (100-145) pre-exercise, 153 (138-178) post exercise). Resting noradrenaline levels were lower in the diabetic (D) compared with the control (C) group (D: 1.66, 0.55-3.92 nmol/l vs. C: 2.96, 2.04-4.49 nmol/l, P less than 0.02). Levels rose during exercise by 79% (25-307%) and 43% (4-90%) respectively (NS). Resting urinary sodium was raised in the diabetic group and fell during exercise (P less than 0.05) (D: 146, 74-244 mumol/min, C: 108.5 (83.4-151.0) pre-exercise vs. D: 73, 48-264 mumol/min, C: 81.7 (23.0-92.0) post exercise). Resting atrial natriuretic peptide levels were lower in the diabetic group (D: 10.1, 4.3-16.9 pmol/l vs. C: 16.0, 9.5-22.9 pmol/l, P less than 0.02) and levels rose significantly in both groups during exercise (D: 25.9, 5.2-38.9 pmol/l vs. C: 28.6, 17.3-47.2 pmol/l, P less than 0.05). We conclude that exercise provokes an exaggerated rise in systolic blood pressure and decrease in urinary sodium excretion in normoalbuminuric diabetic patients. These findings may reflect increased sensitivity to the renin-angiotensin-aldosterone system. Reduced atrial natriuretic peptide levels may stimulate sodium retention and increased blood pressure in early diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗