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Biomedical subjects

A Zeman

Publications and source records attributed to A Zeman.

At least 19 recordsLinked to original sources
PubMed1999

Dyspraxia in a patient with corticobasal degeneration: the role of visual and tactile inputs to action.

OBJECTIVES: To investigate the roles of visual and tactile information in a dyspraxic patient with corticobasal degeneration (CBD) who showed dramatic facilitation in miming the use of a tool or object when he was given a tool to manipulate; and to study the nature of the praxic and neuropsychological deficits in CBD. METHODS: The subject had clinically diagnosed CBD, and exhibited alien limb behaviour and striking ideomotor dyspraxia. General neuropsychological evaluation focused on constructional and visuospatial abilities, calculation, verbal fluency, episodic and semantic memory, plus spelling and writing because impairments in this domain were presenting complaints. Four experiments assessed the roles of visual and tactile information in the facilitation of motor performance by tools. Experiment 1 evaluated the patient's performance of six limb transitive actions under six conditions: (1) after he described the relevant tool from memory, (2) after he was shown a line drawing of the tool, (3) after he was shown a real exemplar of the tool, (4) after he watched the experimenter perform the action, (5) while he was holding the tool, and (6) immediately after he had performed the action with the tool but with the tool removed from his grasp. Experiment 2 evaluated the use of the same six tools when the patient had tactile but no visual information (while he was blindfolded). Experiments 3 and 4 assessed performance of actions appropriate to the same six tools when the patient had either neutral or inappropriate tactile feedback-that is, while he was holding a non-tool object or a different tool. RESULTS: Miming of tool use was not facilitated by visual input; moreover, lack of visual information in the blindfolded condition did not reduce performance. The principal positive finding was a dramatic facilitation of the patient's ability to demonstrate object use when he was holding either the appropriate tool or a neutral object. Tools inappropriate to the requested action produced involuntary performance of the stimulus relevant action. CONCLUSIONS: Tactile stimulation was paramount in the facilitation of motor performance in tool use by this patient with CBD. This outcome suggests that tactile information should be included in models which hypothesise modality specific inputs to the action production system. Significant impairments in spelling and letter production that have not previously been reported in CBD have also been documented.

Apraxias↗
PubMed1997

Bilateral foot-drop in a patient with anorexia nervosa.

We report the occurrence of bilateral foot-drop in a patient with anorexia nervosa. To the best of our knowledge this has not been reported previously. The underlying pathology was found to be peroneal nerve palsy probably related to mechanical pressure at the head of the fibula. Nutritional deficiency may also be implicated.

Adolescent↗
PubMed1996

Oxygen increases the steady-state level of nitrate in denitrifying cells of Paracoccus denitrificans.

The levels of nitrate in denitrifying cells of Paracoccus denitrificans were determined by centrifugation through silicone oil into phosphoric acid and ion-exchange HPLC analysis of the cell lysates, using [14C]sucrose to correct for the trapped external medium. Introduction of oxygen brought about a significant upward shift in the intracellular nitrate concentration. This result calls into question the current thinking that oxygen blocks nitrate respiration primarily due to the inhibition of nitrate transport into the cell.

Biological Transport↗
PubMed1995

Affinity of antigen-specific IgG distinguishes multiple sclerosis from encephalitis.

The characteristics of antigen-specific IgG in patients with multiple sclerosis and patients with encephalitis have been compared. Both groups of patients showed antigen-specific oligoclonal bands locally synthesised in the CSF. When the affinity distribution of the antigen-specific IgG was measured there was a marked difference between the two groups. Encephalitis patients had high affinity antibody against the causative antigen. This was consistent with the antibody undergoing affinity maturation as a result of the immune system fighting a primary infection. Multiple sclerosis patients lacked high affinity response. This lack of high affinity antibody was also seen in those encephalitis patients when antigens other than the causative antigen were studied.

Adolescent↗
PubMed1995

A mutant of Azospirillum brasilense Sp7 impaired in flocculation with a modified colonization pattern and superior nitrogen fixation in association with wheat.

We report here significant phenotypic and genetic differences between Azospirillum brasilense Sp7 and spontaneous mutant Sp7-S and their related properties in association with wheat. In contrast to the wild-type strain of Sp7, colonies of Sp7-S stained weakly with Congo red when grown on agar media containing the dye and did not flocculate in the presence of fructose and nitrate. Scanning and transmission electron micrographs showed clearly that the Sp7-S strain lacked surface materials present as a thick layer on the surface of the wild-type Sp7 strain. Different patterns of colonization on wheat roots between Sp7 and Sp7-S, revealed by in situ studies using nifA-lacZ as a reporter gene, were related to a large increase in nitrogenase activity (acetylene reduction) with Sp7-S in association with normal and 2,4-dichlorophenoxyacetic acid-treated wheat for assays conducted under conditions in which the nitrogenase activity of free-living Azospirillum organisms was inhibited by an excess of oxygen. Randomly amplified polymorphic DNA analysis indicated the close genetic relationship of Sp7-S to several other sources of Sp7, by comparison to other recognized strains of A. brasilense. Genetic complementation of Sp7-S was achieved with a 9.4-kb fragment of DNA cloned from wild-type Sp7, restoring Congo red staining and flocculation.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

The significance of serum oligoclonal bands in neurological diseases.

The presence of oligoclonal bands (OCBs) of immunoglobulin G (IgG) in CSF provides evidence for the occurrence of a humoral immune response, but it is not always appreciated that the oligoclonal IgG may have originated in the serum. To determine the diagnostic significance of serum OCBs 146 patients with serum OCBs were identified among 1874 patients with suspected neurological disorders (7.6%). Clear diagnoses had been made in 112 of these patients: in 56 identical CSF and serum bands were present, revealing a systemic immune response, while in 46 additional unique CSF bands indicated that intrathecal IgG synthesis was also occurring. In the first group neoplasia and peripheral neuropathies accounted for over 50% of the diagnoses, infections and systemic inflammatory disorders for 32%, and multiple sclerosis was diagnosed in only one case. These figures contrast considerably with those reported for patients with CSF OCBs alone. Diagnoses in the second group of patients, with unique CSF OCBs in addition to serum OCBs, resembled those among patients with CSF OCBs alone. Examining CSF and serum in parallel for OCBs of IgG provides more diagnostic information than examining CSF alone, and the latter is potentially misleading.

Antibody Formation↗
PubMed1992

Fluids of the brain and the pathogenesis of MS.

The plaques of multiple sclerosis are generally thought to spread outwards from central veins. We propose that periventricular plaques in the cerebral hemispheres, and superficial plaques in the brain stem and spinal cord, point to the importance of demyelinating factors in the cerebrospinal fluid.

Body Fluids↗
PubMed1992

Progressive multifocal leucoencephalopathy, sclerosing cholangitis, bronchiectasis and disseminated warts in a patient with primary combined immune deficiency.

A 24 year old man presented with an unusual primary combined immune deficiency syndrome characterised by a profound lymphopenia of CD4 cells, selective serum IgG2 subclass deficiency, poor polysaccharide antibody responses, disseminated warts, recurrent sinopulmonary infection and bronchiectasis. The developed progressive multifocal leucoencephalopathy (PML) in association with sclerosing cholangitis. Progressive multifocal leucoencephalopathy (PML) usually occurs as an opportunistic infection in patients with secondary defects in cellular immunity.

Adult↗
PubMed1992

Immunoblotting of transferrin in the identification of cerebrospinal fluid otorrhoea and rhinorrhoea.

Cerebrospinal rhinorrhoea is potentially serious due to the risk from infection. In patients presenting with a nasal discharge of clear fluid it is important to identify the nature of the fluid. Cerebrospinal fluid is readily identified by the presence of asialo-transferrin (tau protein). A method is presented for the identification of tau protein based upon agarose electrophoresis, followed by transfer onto cellulose nitrate membrane and immunochemical detection of transferrin. The method is reliable, sensitive and simple, and requires only basic electrophoresis apparatus.

Asialoglycoproteins↗
PubMed1991

The role of magnetic stimulation as a quantifier of motor disability in patients with multiple sclerosis.

Magnetic stimulation was used to measure motor conduction time (MCT) between head and neck in a prospective longitudinal study of patients with multiple sclerosis (MS) and normal subjects. MCT measurements showed a high degree of reproducibility in normal subjects and patients with stable MS. In patients with definite MS, there was significant positive correlation between MCT and motor disability. In patients treated with steroids for relapse of MS, there was significant shortening of MCT following treatment in those who clinically improved, but not in those who were clinically unchanged. In a smaller group of patients followed for 3 months, MCT changes tended to mirror the clinical pattern. Magnetic stimulation should prove a useful tool for the quantification of motor disability, and monitoring the response to new treatments in MS.

Adrenal Cortex Hormones↗
PubMed1991

Acute infection with human immunodeficiency virus presenting with neurogenic urinary retention.

Several neurological presentations of acute primary infection with HIV have recently been described. A previously unrecognised presentation with neurogenic retention of urine and sacral sensory loss is reported. The case is discussed in the context of other neurological syndromes associated with seroconversion to HIV, and of other viral causes of acute retention of urine. The importance of considering the possibility of primary HIV infection in a wide range of self-limiting neurological disorders is emphasised.

Acute Disease↗