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Biomedical subjects

A Kirk

Publications and source records attributed to A Kirk.

At least 55 records · Page 3Linked to original sources
PubMed1991

Dementia with leukoencephalopathy in systemic lupus erythematosus.

Neurologic manifestations, afflicting up to 70% of SLE patients, include psychosis, seizures, chorea, neuropathies, and stroke. MRI is useful in evaluation of lupus patients and several reports have documented cerebral atrophy or focal hyperintensities. We report an unusual MRI appearance in a 56-year-old woman with SLE, diagnosed on the basis of pleuritis, lymphopenia, anti-DNA antibodies, and neurologic involvement. She reported recent onset of Raynaud's phenomenon and generalized macular rash. She presented after two months of gradual deterioration with memory loss, flattened affect, dysphagia, dysarthria, anomia, and somnolence, without focal neurologic signs. Investigations included elevated ESR, reduced complement, normal CSF without oligoclonal bands, negative viral serology, normal hormone and vitamin levels, normal renal and hepatic function. Neuropsychologic testing showed widespread impairment (WAIS-R: FSIQ-63; WMS-69; DRS-98; RCPM-14; WAB AQ-78.8). CT was normal but MRI showed strikingly symmetric, confluent hyperintensities extensively involving cerebral and cerebellar white matter on T1 and T2 weighted scans. Basal ganglia and subependymal and subcortical white matter were spared. Treated with prednisone, the patient made a gradual, but incomplete, recovery. These MRI findings may reflect widespread vasculopathy or direct immunologic brain insult with or without immunologic blood-brain barrier disruption.

Brain Diseases↗
PubMed1991

Auricular myoclonus.

We describe a young man with a two and a half year history of idiopathic irregular contractions of an antitragicus muscle in the absence of a more generalized movement disorder. These contractions persisted in sleep and could not be replicated voluntarily. Because proximal nerve block temporarily eliminated the movements and complex hand movements reduced their amplitude and frequency, we suspect a central generator. However, these movements were not associated with any known pathologic condition.

Adult↗
PubMed1991

Phonolexical agraphia. Superimposition of acquired lexical agraphia on developmental phonological dysgraphia.

Study of neuropsychological sequelae of a focal acquired brain lesion may bring out and help delineate the features of a compensated developmental language disorder and its anatomical substrate. A left-handed man with a history of phonological developmental dyslexia and dysgraphia learned in early adulthood to read and write using a lexical system. Following a small posterior right parietal infarct when aged 56 yrs he developed a severe agraphia displaying features of phonological dysgraphia with impaired segmentation and features of lexical agraphia. Writing was severely impaired for all classes of word and nonword stimuli but his errors did not resemble those attributable to a deficit in the system responsible for the short-term storage of the graphemic representation of a word (graphemic output buffer). These observations imply that an acquired lexical agraphia has been superimposed on his developmental phonological dysgraphia, resulting in a combined or 'phonolexical' agraphia.

Agraphia↗
PubMed1990

Identification of hematopoietic progenitors of macrophages and dendritic Langerhans cells (DL-CFU) in human bone marrow and peripheral blood.

Colonies of cells with distinctive dendritic appearance were observed in methylcellulose cultures of human bone marrow and peripheral blood mononuclear cells (PBMC). Such cells appeared alone in colonies of less than 50 cells, together with macrophages in mixed colonies and also within clusters of T lymphocytes at high culture cell numbers. The morphologic resemblance to lymphoid dendritic cells was confirmed by electron microscopy and the cells were distinguished from macrophages by immunoenzymatic and immunogold labeling with monoclonal antibodies (MoAbs). Like macrophages they were HLA-DR+ and CD4+. However, they lacked nonspecific esterase and the macrophage cytoplasmic marker Y1/82A. Most strikingly, cells were strongly HLA-DQ+ and expressed CD1a (T6), which is characteristic of skin Langerhans cells. Their functional similarity to lymphoid dendritic cells was demonstrated by their ability to stimulate allogeneic mixed leukocyte reactions. Dendritic cell colony numbers were estimated in both bone marrow and peripheral blood of controls and in leukemia and lymphoma patients before and after chemotherapy. Colony numbers were low in control blood and in patients before treatment (less than 1.0 to 3.7/10(5) cells). However, during hematopoietic recovery the mean value increased to 37.5/10(5) cells and this increase correlated closely with the observed increase in circulating colony forming unit-granulocyte macrophage (CFU-GM) in individual patients. Autoradiographic studies demonstrated mitotic activity within CD1a+ colonies and a linear relationship between cultured cells and both pure and mixed colonies was consistent with their derivation from a single precursor. These data indicate that a novel hematopoietic progenitor of dendritic/Langerhans cells (DL-CFU) may now be identified in a clonal assay system and suggest a probable common progenitor for these cells and macrophages.

Antibodies, Monoclonal↗
PubMed1989

Hemispheric contributions to drawing.

The drawings of 69 consecutive stroke patients with single cerebral lesions on CT and of 33 normal controls, were analyzed by two independent observers using a standardized scoring system. The drawings of left brain damaged subjects (LBD) were more impaired overall than those of right brain damaged subjects (RBD). RBD drawings displayed hemispatial neglect and impaired spatial relationships. LBD drawings were simplified and exhibited low level errors of execution. Lesion size correlated significantly with drawing impairment in RBD but not in LBD. No relationship between intrahemispheric lesion location and drawing quality was found. However, severity of hemiparesis correlated significantly with drawing impairment in LBD. Performance on a visuospatial perceptual task correlated better with overall drawing quality for RBD than for LBD. Our data suggest that neglect and a visuospatial deficit impair drawing in RBD while dominant hand paresis and a conceptual impairment which parallels comprehension impairment contribute to LBD drawing disability.

Aged↗
PubMed1989

The recovery of circulating progenitor cells after chemotherapy in AML and ALL and its relation to the rate of bone marrow regeneration after aplasia.

Peripheral blood levels of BFU-e, CFU-GM and CFU-mix were studied serially in nine patients with acute leukaemia in remission during the period of recovery that followed induction or consolidation chemotherapy. Following 23 courses of treatment in the nine patients, the values for all three classes of progenitor were found to be higher in ALL than in AML (mean peak CFU-GM levels 5.8 x 10(3)/ml and 0.8 x 10(3)/ml respectively) and the highest levels were observed in patients recovering the most rapidly from bone marrow aplasia. Peak levels of these progenitors correlated best with the rate and extent of platelet recovery and all patients achieving blood levels of greater than 1.0 x 10(3) CFU-GM/ml had recovered greater than 100 x 10(9)/l platelets by 20 d and had peak platelet counts of greater than 400 x 10(9)/l within 40 d following chemotherapy. The peak values for circulating progenitors fell markedly after repeated courses of treatment in three of the five AML patients studied and this is likely to limit useful harvesting of such cells during later consolidation courses in this disease.

Adolescent↗
PubMed1989

Ranitidine fails to suppress the growth in vitro of haemopoietic progenitors from human peripheral blood or bone marrow.

Ranitidine was added in various concentrations (25-1600 ng/ml) to clonal assays of haemopoietic progenitors of normal human peripheral blood or bone marrow. Although a significant reduction in colonies forming from granulocyte-macrophage progenitors (CFU-GM) was demonstrated at the lowest drug concentration, no significant growth suppression was seen at higher concentrations. There was no evidence for growth inhibition of either erythroid progenitors (BFU-E) or pluripotent progenitors (CFU-mix) at any of the drug concentrations studied. A direct toxic effect of ranitidine on normal haemopoietic progenitors thus appears an unlikely cause of cytopenias observed during treatment.

Bone Marrow Cells↗
PubMed1989

The prediction of violent behavior during short-term civil commitment.

The predictive validity of the clinical judgment of dangerousness in the context of short-term civil commitment was studied prospectively by comparing the behavioral scale ratings of both verbal and physical aggression between 37 persons committed on the basis of "danger to others" versus 31 persons committed on other grounds. No statistically significant difference was found between these two groups of detainees with regard to the levels of aggression measured during their approximately three-day detention. This finding is in agreement with abundant previous research which documents the inability of psychiatrists to accurately predict future dangerousness, prompting the author to suggest that the "dangerousness" criterion for civil commitment be rejected. Although society is unlikely to resurrect the broadly defined "in need of treatment" criterion because of its historically demonstrated ever present potential for abuse, the author suggests an alternative criterion for civil commitment which, in perhaps a more well-defined and more practical way, would allow the state to maintain its doctrine of parens patriae toward mental patients.

Adult↗
PubMed1988

Endogenous erythroid clones (EEC) in polycythaemia and their relationship to diagnosis and the response to treatment.

The growth in culture of circulating erythroid progenitors (BFU-e) from 34 patients with erythrocytosis was evaluated together with the clinical and bone marrow features at presentation and the subsequent response to treatment. Clonal erythroid growth in vitro in the absence of added erythropoietin (EEC) was observed in 17/18 patients with clinically unequivocal polycythaemia vera and in these patients bone marrow morphology was also abnormal. EEC were also present in three out of five patients with only a single minor criterion of that disease but none of the 11 patients without major or minor criteria or evidence of secondary polycythaemia were EEC positive. This group had a very low incidence of bone marrow abnormalities, was probably heterogenous in nature and included two patients with elevated serum immunoreactive erythropoietin of unknown cause. The reduction in haematocrit following treatment was assessed in EEC positive and negative patients and was found to be inferior in those lacking EEC. Thus both the poor therapeutic response and the low incidence of bone marrow abnormalities in patients lacking any other clinical features of polycythaemia vera correlated closely with the absence of EEC in in vitro culture. Myeloproliferative disorder may therefore be an unlikely cause of the erythrocytosis in such individuals.

Adolescent↗
PubMed1986

HLA antigens in palindromic rheumatism and palindromic onset rheumatoid arthritis.

Fifty patients who presented with typical palindromic rheumatism of at least 6 months' duration were tissue-typed for HLA A, B, C antigens. DR typing was also performed but was not possible for technical reasons in three patients. Twenty-three patients who had progressed to definite or classical rheumatoid arthritis (RA) after a mean interval of 5 years were compared with 20 patients whose palindromic attacks had persisted over a similar period. Both groups showed a significantly higher frequency of DR4 antigen than a control population. The RA group also showed an increased frequency of DR1. There was no significant difference in the frequency of DR4 or any other DR antigen between the two patient groups. The frequency of B27 antigen was significantly higher in the palindromic group compared with the controls. It is suggested that although DR4 may be associated with a tendency to inflammatory joint problems, environmental or other unrelated genetic factors may be more important in determining the progression of palindromic rheumatism to RA.

Arthritis, Rheumatoid↗
PubMed1982

Polymorphonuclear function in Behçet's syndrome.

Three aspects of polymorphonuclear leucocyte (PMN) function were studied in 19 patients with Behçet's syndrome (BS). By 2 different techniques directed motility was found to be increased. This increase was largely due to the subgroup of patients with ocular involvement. Counts of absolute numbers of cells migrating highlighted this finding. No difference was found in the phagocytic or adherent properties of PMN in Behçet's syndrome. Increased PMN motility in Behçet's syndrome may contribute to the expression of the syndrome. It remains to be tested whether altered PMN motility in this syndrome is genetically linked.

Adult↗
PubMed1981

Pineal complex of the clawed toad, Xenopus laevis Daud.: structure and function.

The morphological and physiological properties of the pineal complex of Xenopus laevis were investigated in larval, juvenile and adult animals. In a representative majority of adult X. laevis, the frontal organ does not display signs of degeneration. Fully differentiated frontal organs contain photoreceptors typical of the pineal complex of lower vertebrates. By means of the acetylcholinesterase (AChE)-reaction approximately 30 neurons of two different types were demonstrated in the frontal organ. The frontal-organ nerve is composed of approximately 10 myelinated and 40 unmyelinated nerve fibers. The neuropil areas of the frontal organ are generally similar to the corresponding structures of the intracranial epiphysis. The neuronal apparatus of the epiphysis cerebri of X. laevis consists of (i) photoreceptor cells, (ii) approximately 100 AChE-positive neurons, (iii) complex neuropil areas, and (iv) a pineal tract formed by approximately 10 myelinated and approximately 100 unmyelinated nerve fibers. Some of them exhibit granular inclusions indicating that pinealopetal elements may enter the pineal complex of X. laevis via this pathway. The topography of the pineal tract of X. laevis differs considerably from that in ranid species. The most conspicuous element of the plexiform zones is the ribbon synapse. The basal processes of the photoreceptor cells may be presynaptic elements of simple, tangential, dyad or triad synaptic contacts. Conventional synapses were observed only occasionally. Electrophysiological recordings revealed that the pineal complex of Xenopus laevis is directly sensitive to light. In response to light stimuli, two types of responses, achromatic and chromatic, were recorded from the nerve of the frontal organ. In contrast, the epiphysis exhibited only achromatic units. The opposed color mechanism of the chromatic response showed a maximum sensitivity at approximately 360 nm for the inhibitory and at 520 nm for the excitatory event. The action spectrum of the achromatic response of the epiphysis and the frontal organ peaked between 500 and 520 nm and showed no Purkinje-shift during dark adaptation. The functional significance of these phenomena is discussed.

Acetylcholinesterase↗