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Biomedical subjects

A Burns

Publications and source records attributed to A Burns.

At least 127 records · Page 7Linked to original sources
PubMed1995

Two cases of Wegener's granulomatosis involving the pituitary.

We describe two patients with Wegener's granulomatosis involving the pituitary. The diagnosis of Wegener's granulomatosis was inferred from the histological appearance of biopsy tissue and the presence of anti-neutrophil cytoplasmic antibodies with cytoplasmic distribution in the first case, in which disease remained confined to the pituitary, causing anterior and posterior pituitary dysfunction. In the second case the diagnosis was made by the progressive involvement of other organ systems, compatible histology and the presence of anti-neutrophil cytoplasmic antibodies with cytoplasmic distribution. In neither patient did posterior pituitary dysfunction respond to immunosuppressive therapy, despite remission of other features of systemic vasculitis. Panhypopituitarism in association with isolated pituitary Wegener's granulomatosis has not previously been described.

Adult↗
PubMed1995

Regulation of the segmental swim-generating system by a pair of identified interneurons in the leech head ganglion.

1. The aim of this study was to identify neurons that modulate activity of segmental swim gating interneurons. We found a pair of bilaterally symmetrical interneurons, cells SE1, whose activity level directly influences three groups of segmental neurons associated with generating swimming in the medicinal leech. 2. The somata of cells SE1 are located on the dorsal surface of the subesophageal ganglion. Their axons extend most, if not the entire, length of the ventral nerve cord and appear to make identical connections with the same group of swim-generating neurons in all segmental ganglia. 3. Cells SE1 excite monosynaptically all segmental swim gating interneurons, cells 204, examined. The level of excitation in cell 204 is directly correlated with the firing frequency of cell SE1. In most quiescent preparations (when the preparation is not swimming) hyperpolarization of a single cell SE1 eliminates all excitatory synaptic input to cells 204. 4. Cells SE1 excite monosynaptically three swim oscillatory interneurons, cells 115, 28, and 208. The strength of the connection from cell SE1 to cell 115 is stronger than the connection from cell SE1 to either cells 28 or 208. The level of excitation in cell 115 is directly correlated with the firing frequency of cell SE1. In most quiescent preparations, hyperpolarization of a single cell SE1 eliminates all excitatory synaptic input to cell 115 but has only a minor effect on the level of activity in cells 208 and 28. 5. Due most likely to the strong and direct connections cells SE1 have with swim gating and oscillatory interneurons, brief stimulation of cell SE1 can elicit swimming. Swimming generally occurs within 1 s after stimulation of cell SE1. During swimming, the membrane potential of cell SE1 depolarizes by 2-5 mV, and its firing frequency increases. Brief depolarization of cell SE1 during swimming reliably shifts the phase of the swimming rhythm, whereas longer periods of depolarization increase both swim period and burst duration. 6. Excitatory motor neurons to the dorsal longitudinal muscles, cells 3, 5, and 7, are strongly excited by stimulation of cell SE1. The firing frequency of cell 3 is positively correlated with the firing frequency of cell SE1. 7. The results of this study indicate that cells SE1 can modulate the level of excitation in three groups of neurons associated with generating leech swimming.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1995

Cerebral venous sinus thrombosis in minimal change nephrotic syndrome.

Three cases of cerebral venous sinus thrombosis (CVST) occurring in patients with minimal change nephrotic syndrome (MCNS) are described. Personality change in two of these patients was wrongly attributed to steroid therapy prior to the discovery of the CVST. In addition, von Willebrand factor (vWF) levels were grossly elevated in one patient, during a previous relapse of MCNS, prior to developing CVST, and may be a useful prognostic tool in predicting thrombotic events in nephrotic patients.

Adolescent↗
PubMed1994

Deletion of the propeptide of apolipoprotein A-I impairs exit of nascent apolipoprotein A-I from the endoplasmic reticulum.

Human apolipoprotein (apo) A-I is secreted as a proprotein of 249 amino acids and is processed extracellularly to the mature form (243 amino acids) by removal of a six-residue propeptide segment. We have examined the role of the apoA-I propeptide in intracellular transport and secretion using transfected baby hamster kidney cells that secreted either proapoA-I (from the wild-type cDNA, A-Iwt) or mature-form apoA-I (from A-I delta pro, a cDNA in which the propeptide sequence was deleted). Deletion of the propeptide from the apoA-I sequence did not affect the rate of apoA-I synthesis, nor did it affect the fidelity of proteolytic removal of the prepeptide. However, the propeptide deletion caused mature-form apoA-I to accumulate within the cells as determined by pulse-chase experiments; the intracellular retention times for the mature-form apoA-I in which the propeptide was prematurely removed was three times longer than that of proapoA-I (t1/2 > 3 h compared with approximately 50 min). There was no detectable degradation of either form of newly synthesized apoA-I. Immunofluorescence microscopy revealed that, whereas the proapoA-I was located predominantly in the Golgi apparatus, large quantities of the mature-form apoA-I were detected in the endoplasmic reticulum and very little was in the Golgi apparatus of A-I delta pro-transfected cells. These findings suggest that the propeptide sequence may be involved in the intracellular transport of apoA-I from the endoplasmic reticulum to the Golgi apparatus. We propose that the function of the propeptide sequence is to facilitate efficient transport of apoA-I through the secretory pathway.

Amino Acid Sequence↗
PubMed1994

Disproportionate loss of noradrenergic and cholinergic neurons as cause of depression in Alzheimer's disease--a hypothesis.

Forty-two patients with neuropathologically confirmed Alzheimer's disease, who had been examined prospectively, had a significant decrease of neuron numbers in the locus coeruleus, substantia nigra, and basal nucleus of Meynert compared to 10 age-matched, non-demented controls. A subgroup of 12 demented patients with a history of depression had significantly lower neuron numbers in the locus coeruleus and slightly higher neuronal density in the basal nucleus of Meynert. We hypothesize that a noradrenergic/cholinergic imbalance may promote the development of depressive features in patients with Alzheimer's disease.

Aged↗
PubMed1994

Blood pressure predicts insulin requirement and exogenous insulin is associated with increased blood pressure in women with gestational diabetes mellitus.

Fifty gestational diabetic women were studied to determine the interaction of blood pressure, insulin resistance, and the effect of exogenous insulin on blood pressure response. Gestational diabetes was diagnosed according to the criteria affirmed by the Third International Workshop-Conference on Gestational Diabetes at 20 to 32 weeks' gestation. At diagnosis, all women were placed on a standard diet and performed glucose monitoring on rising and 1 hour after meals. The criteria for initiation of insulin included fasting whole blood finger stick glucose more than 90 mg/dL, ketonuria that could only be cleared by increasing carbohydrate to a level causing postprandial hyperglycemia, or postprandial glucose levels at 1 hour above 140 mg/dL. Of the initial cohort, 28 required insulin to maintain target glycemia. Within this group, there was a significant positive correlation between mean arterial pressures at initiation of therapy for gestational diabetes mellitus and insulin requirement quantified by the amount of insulin required to maintain euglycemia at term (r2 = 0.259; P = 0.006). The initiation of insulin was associated with a significant blood pressure increase in this group when compared with values prior to insulin administration or to values in the group treated with diet alone. These observations are consistent with an interaction of blood pressure and insulin resistance as reflected by insulin requirement in women with gestational diabetes mellitus.

Adult↗
PubMed1994

Delusional misidentification in Alzheimer's disease: a summary of clinical and biological aspects.

Delusional misidentification symptoms (DMS) are common in Alzheimer's disease (AD) and they are frequent sources of serious distress for patients and particularly caregivers. We observed DMS in around 30% of the patients with moderate to severe AD in two independent prospective studies; the Capgras type, phantom boarder, mirror and TV DMS were found most frequently. Patients with DMS showed increased EEG delta-power over the right hemisphere, their CT scans showed more severe right frontal lobe atrophy, and the number of their pyramidal cells in area CA1 was lower than in the patients without DMS. This may indicate that the development of DMS in AD can be promoted by certain patterns of brain degeneration which affect systems relevant to the recognition and updating of memories, while verbal skills may initially be left largely intact.

Aged↗
PubMed1994

Neuropathological correlates of psychotic phenomena in confirmed Alzheimer's disease.

BACKGROUND: The prevalence of psychotic phenomena in confirmed Alzheimer's disease (AD) and their potential neuropathological correlates have rarely been the subject of prospective investigation. METHOD: Psychopathological disturbances were recorded prospectively according to the Geriatric Mental State Schedule and the CAMDEX: The frequency of these phenomena and neuropathological changes were examined in 56 patients with definite AD. RESULTS: Hallucinations had been documented in 13 patients, paranoid delusions in 9 and delusional misidentification (e.g. the Capgras-type and the 'phantom boarder' symptoms) in 14 patients. Misidentifications were associated with lower neurone counts in the area CA1 of the hippocampus. Delusions and hallucinations were observed in patients with less severe cell loss in the parahippocampal gyrus and with lower cell counts in the dorsal raphe nucleus. A decrease of neurones in the locus coeruleus in a subset of depressed patients with AD had been reported earlier. Delusions and delusional misidentification were common in 5 patients with basal ganglia mineralisation, but there was no statistically significant association of these symptoms with the presence of Lewy bodies in the brainstem and neocortex of our patient sample. CONCLUSIONS: These findings are compatible with the view that morphological changes in certain brain areas may promote the development of psychotic phenomena in AD. AD may offer a model for the understanding of pathomechanisms underlying the development of psychopathological disturbances in other psychoses with more discrete neuropathological changes.

Aged↗
PubMed1993

The delusional misidentification syndromes in patients with and without evidence of organic cerebral disorder: a structured review of case reports.

Two series, each of 50 cases of delusional misidentification reported in the literature, were analyzed in order to study the interaction between organic and functional mental processes. The details of the time course of the development of the delusional misidentification and related mental symptoms, the phenomenology, and evidence of cognitive impairment and/or cerebral damage were recorded. The first series of cases included delusional misidentification either of place, and/or of persons; the second series was limited to cases, published since 1977, with delusional misidentification of person, who had had an electroencephalogram (EEG) and/or computerised tomographic (CT) brain scan. Paranoid delusions, preceding the onset of the delusional misidentifications, were more common in cases without evidence of organic cerebral disorder. In the second series there was good evidence of an inverse relationship between the presence of paranoid delusions preceding the delusional misidentification, and the intensity of organic cerebral disorder; (1) no evidence clinically or on investigation, (2) evident only on investigation, or (3) evident clinically. In the first series delusional misidentification of place was more common in cases with evidence of organic brain disorder, whereas delusional misidentification of person was more common with functional mental disorder. Nevertheless the delusional misidentification was equally likely to involve objects of personal significance whether or not there was evidence of organic cerebral disorder. Paramnesic misidentifications were associated with both memory impairment and disorientation for time.

Adult↗
PubMed1993

The effect of adrenomedullin on the isolated heart.

A novel peptide found in human blood, adrenomedullin (ADM), has been shown to have systemic vasodepressor activity in the rat. However, the direct effects of ADM on cardiac function are unknown. Results of the present study demonstrate that ADM13-52 possesses marked systemic vasodepressor activity in the anesthetized rat. Although ADM13-52 modestly decreased peak systolic pressure (PSP) indicating mild negative inotropic activity, the present data suggest that bolus administration of ADM decreases systemic arterial pressure by dilating the systemic vasculature. The present data also suggest that only a portion of the ADM molecule is necessary to produce systemic vasodilation.

Adrenomedullin↗
PubMed1993

Neuropathological basis for drawing disability (constructional apraxia) in Alzheimer's disease.

The performance on four drawing tasks was studied in a sample of patients with verified Alzheimer's disease in order to examine the relationship of 'constructional apraxia' to neuropathological changes in the parietal lobe and in other brain areas. Twenty-three patients were able to attempt to copy pentagons, a spiral and a three-dimensional drawing of a house, 22 patients were able to draw a clock-face spontaneously. The results were rank-ordered by two independent raters. The values obtained in the different drawing tasks were correlated significantly with each other, with global estimates of cognitive performance (CAMCOG, Mini-Mental State), with a shorter duration of illness, higher brain weight (in the subsample of female patients), higher counts of large neurons in the parahippocampal gyrus and hippocampus, but not in the parietal lobe. This suggests that there is no specific relationship between 'constructional apraxia' and neuropathological changes in the parietal lobes of patients with advanced Alzheimer's disease, but that there is a correlation between widespread brain changes and several neuropsychological deficits, one of them being drawing disability.

Alzheimer Disease↗
PubMed1993

The Lewy-body variant of Alzheimer's disease. Clinical and pathological findings.

At post-mortem, Lewy bodies (LBs) were found in the brainstem and neocortex of eight out of 65 patients who had been collected during a prospective long-term study on clinically diagnosed Alzheimer's disease. All eight patients had accompanying Alzheimer pathology which was less severe than in a sample of eight age- and sex-matched patients from the same study with neuropathologically verified Alzheimer's disease. Parkinsonian features were more common in patients with LBs. There were no particular differences in duration of illness, severity of cognitive impairment, presence of hallucinations, or fluctuations in the course of illness. Frontal cerebral atrophy was more marked in patients with LBs, as was the loss of neurons in the basal nucleus of Meynert and the substantia nigra. Cognitive performance correlated with the number of pigmented neurons in the substantia nigra. We conclude that the differential diagnosis of LB dementia should be considered in patients satisfying NINCDS-ADRDA criteria for Alzheimer-type dementia who show marked Parkinsonian features and a frontal accentuation of cerebral atrophy.

Aged↗
PubMed1993

Neuropathological correlates of behavioural disturbance in confirmed Alzheimer's disease.

Clinico-pathological correlations were examined in 54 patients with neuropathologically verified Alzheimer's disease (AD) who were part of a prospective study. Behavioural disturbance was documented using an expanded version of the Stockton Geriatric Rating Scale (SGRS). The subscores for physical disability (P), apathy (A) and communication failure (C) (summation score PAC) were closely correlated and were high in most patients during the late stages of illness. High PAC scores correlated with an earlier onset and longer duration of illness, lower brain weight, more severe tangle pathology in the parahippocampal gyrus and the frontal and parietal neocortex, and lower neuron counts in the hippocampus and basal nucleus of Meynert. Features of the Klüver-Bucy syndrome (range behaviour and hypermetamorphosis) were significantly associated with lower counts of large neurons in the parahippocampal gyrus and parietal neocortex, but not with more severe plaque or tangle formation or with neuronal loss in the subcortical nuclei. No correction was made for multiple comparisons. These findings may signify decreased cortical inhibition in patients with relatively well preserved subcortical structures who show features suggestive of the Klüver-Bucy syndrome. High PAC scores on the SGRS could reflect more advanced and widespread cerebral pathology in the end stages of AD.

Activities of Daily Living↗