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Biomedical subjects

I Allen

Publications and source records attributed to I Allen.

18 recordsLinked to original sources
PubMed1993

Pathogenesis of multiple sclerosis--the immune diathesis and the role of viruses.

Although the evidence of involvement of viruses in the pathogenesis of MS is largely circumstantial, the pattern of association is constant, with little evidence for direct viral infection of the CNS but with a consistent immune response to several common viruses. In parallel with these studies, epidemiological studies, while indicating genetic predisposition, favor an environmental pathogenetic factor and experimental models indicate that viruses can induce demyelination either by oligodendrolysis or by a variety of immune mechanisms with or without persistence in the CNS. In elucidating the pathogenesis of MS, the challenge is to understand the basis of the immune abnormalities, with intrathecal synthesis of viral antibodies and abnormal immune responses to some viruses, and to relate these to the MRI abnormalities which indicate periodic BBB breakdown. There is strong evidence that the breakdown is associated with inflammation. and that cytokines, particularly TNF, may play a role in demyelination. In conclusion, therefore, several factors are probably key in our understanding of MS. These include: (i) the genetic control of the immune system and its interaction with viral antigen; (ii) related effects on cerebral endothelium including cytokine and adhesion molecule regulation; and (iii) associated glial and axonal responses. Such an approach to the pathogenesis of MS may not identify a specific cause. It may, however, indicate that a pathological cascade can be "triggered" by several common viral infections and that therapy can be used to intervene at several points in the pathological response.

Animals↗
PubMed1990

Clinical, biochemical and immunoelectron microscopical evidence of dual hormone production in a mammosomatotroph cell adenoma.

This paper reports the occurrence of a rare, yet distinct pituitary adenoma which was surgically removed from a 42-year-old male with both clinical and biochemical evidence of acromegaly and mild hyperprolactinaemia. The monomorphic adenoma consisted of mature cells which were ultrastructurally indistinguishable from those of a prolactinoma. Electron immunocytochemistry, including a series of double-labelling techniques using selected colloidal gold particles as markers, indicated the presence of a pituitary adenoma in which the cells were capable of simultaneously producing growth hormone and prolactin and packaging them within the same secretory granule. This is thought to represent a mammosomatotroph cell adenoma.

Adenoma↗
PubMed1990

Rating of the lesions in senile dementia of the Alzheimer type: concordance between laboratories. A European multicenter study under the auspices of EURAGE.

The study reported was intended to compare the impressions and analyses of investigators from 11 different laboratories on 2 slides, each from 6 cases with varying quantities of neuropathological change of the type found in Alzheimer's disease and normal ageing. The material came from 6 selected female patients over 75 years of age all of whom had been examined in detail and assessed by the Blessed Test Score. Two were severely demented, 2 mildly demented and 2 were considered to be normal. Unstained paraffin-embedded slides were sent to the investigators, the choice of the staining techniques being left to each laboratory. A quantitative evaluation of the changes was requested in 2 specified areas of the hippocampus and in the first temporal gyrus. Subjective scores of severity and a final guess about the pre mortem intellectual status (demented or not) were asked. The 11 replies were analyzed. A total of 14 different staining techniques were used. Absolute values of density differed much from one investigator to another, for senile plaques as well as for neurofibrillary tangles. Statistical analysis showed that concordance might be improved by the use of corrective factors which would standardize the scales of measurement. The ranking of the slides in increasing order of severity was in good agreement for 9 out of 11 observers concerning the neurofibrillary tangles and 3 out of 9 observers concerning the senile plaques. The correlation between the intellectual status and the density of lesions was higher for neurofibrillary tangles than for senile plaques. The subjective scores were in better agreement for the severely affected cases than for the mildly affected ones. The lowest correlation with intellectual deficit was obtained with the quantitative scores which took into account only the senile plaques or only the hippocampal lesions. The highest correlation coefficients were obtained with the subjective scores. The observers guessed correctly the intellectual status of the 2 most affected cases and often disagreed for the intermediate and normal cases. Neuropathology is mandatory for the diagnosis of definite Alzheimer's disease. Quantitative assessment is useful in cases with few lesions and light dementia but the neuropathological diagnostic procedure has to be more strictly standardized before quantitative histopathological criteria can be reliably transferred from one laboratory to another, especially when mildly affected cases are involved. Concordance seems presently easier to obtain by ranking the lesions and the cases in increasing order of severity than by using quantitative values of density.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1983

The establishment and characterization of a cell line and mouse xenografts from a human malignant melanoma.

A permanent cell line has been established from a human intracranial secondary melanoma. During 3 years of continuous growth in vitro the cells have maintained their characteristic phenotypic properties including melanin production. The cultured cells are highly tumorigenic in the athymic mouse and the tumours produced are histologically identical to the human tumour of origin.

Animals↗
PubMed1980

The nodular form of polymyositis--a possible manifestation of vasculitis.

A case of the nodular form of polymyositis is reported in which muscle necrosis and inflammation, and fibrosis of subcutaneous fat were observed. Although the patient had a short history, the presence of extensive fibrosis with acute lesions indicated that the disease had been present for some time. In addition to the nodular lesions, the patient had clinical, electrophysiological and pathological evidence of a more generalised myopathy. The subsequent development of a rash resembling that of vasculitis and a peripheral nerve lesion, suggested that the localised nodular myositis was associated with systemic vasculitis. Although immunoglobulin and complement deposits were not detected in blood vessel walls in muscle or skin, a positive reaction to intradermal injection of autologous serum suggested the presence of circulating immune complexes.

Adipose Tissue↗