PubMed Health⌕ Search

Biomedical subjects

J Patterson

Publications and source records attributed to J Patterson.

At least 37 records · Page 2Linked to original sources
PubMed1990

Tc99m HM-PAO single photon emission computed tomography in temporal lobe epilepsy.

We present the results of single photon emission computed tomography (SPECT) in 40 patients with temporal lobe epilepsy and normal computed transmission tomography (CT). Abnormalities of regional cerebral blood flow were found in 26 patients. There was focal hypoperfusion alone in 14, focal hyperperfusion alone in 6, and both types of abnormality in 6. In 4 patients there were bilateral abnormalities. Repeat SPECT showed persistence of interictal hyperperfusion in 5/12 patients. There were no significant correlations between SPECT findings and clinical parameters, and no relation between the persistence of interictal hyperperfusion and time since last seizure or seizure frequency. Where SPECT and multiple surface EEG recordings were both lateralising, agreement between them was good. The results of this study support the usefulness of HMPAO SPECT in detecting lateralising abnormalities in temporal lobe epilepsy. Interictal hyperperfusion may be commoner than previous publications suggest, and may be persistent in some cases.

Adolescent↗
PubMed1990

CT, MR and SPECT imaging in temporal lobe epilepsy.

Cranial computed tomography (CT) with modified temporal lobe technique, 0.15T magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) were carried out on 30 patients with intractable temporal lobe epilepsy. Lateralising abnormalities were detected in 21/30 patients overall. Specific lesions were detected by CT in one patient and by MRI in seven patients (in one case bilateral). In addition CT detected asymmetry of the sylvian fissures or temporal horns in 10 patients, and MRI in eight patients. SPECT detected lateralising abnormalities in 19 patients (in five cases bilateral). It is concluded that low field MRI is superior to modified CT in demonstrating subtle structural lesions of the temporal lobe. Functional scanning with SPECT supports the evidence of origin of an epileptic focus in a substantial proportion of cases and may improve the selection of patients for surgery.

Adolescent↗
PubMed1990

Measurements of regional cerebral blood flow and cognitive performance in Alzheimer's disease.

Single photon emission computed tomography (SPECT) with 99mTc-HMPAO was used to image 26 patients with dementia of the Alzheimer type (DAT) and 10 healthy controls. Regional cerebral blood flow (rCBF) data indicated a relative sparing of the occipital regions in DAT. Normalisation to occipital flow illustrated highly significant CBF deficits in a number of cortical regions, particularly in the left and right posterior--temporal cortex in DAT compared to controls. The cognitive performance of DAT patients was measured using a clinical cognitive assessment procedure (CAMCOG) and numerous correlations between these scores and rCBF were obtained. The implications and value of this investigative technique are discussed.

Aged↗
PubMed1989

A double-blind randomized placebo controlled trial of thromboprophylaxis in major elective general surgery using once daily injections of a low molecular weight heparin fragment (Fragmin).

The safety and efficacy of the low molecular weight heparin fragment (Fragmin) administered as a single daily injection of 2,500 anti Xa units has been evaluated in 183 patients undergoing major elective general surgery. The study was double-blinded and placebo controlled. The active agent, or placebo, was given subcutaneously with the preoperative medication and continued postoperatively for 5-9 days. Ninety five patients received Fragmin and 88 were randomized to receive the placebo. The clinical characteristics of the two treatment groups were similar. Fragmin significantly reduced the incidence of deep venous thrombosis, as detected by a positive 125I fibrinogen leg scan, relative to the placebo treated patients (4/95, 4.2% v. 14/88, 15.9%; p = 0.008). The thrombotic events occurred predominantly (73%) amongst patients with malignancy. Haemorrhagic endpoints necessitating discontinuation of the trial treatment were 4% in each group. No severe adverse reactions or drug related deaths occurred. These results indicate that 2,500 anti Xa units of Fragmin given only once daily is effective thromboprophylaxis for patients undergoing major elective abdominal surgery.

Aged↗
PubMed1989

Complete sequence of the lamprey fibrinogen alpha chain.

The complete amino acid sequence of the lamprey fibrinogen alpha chain has been determined by a combination of peptide sequencing and cDNA and genomic cloning. The chain, which has an apparent molecular weight by dodecyl sulfate-polyacrylamide gel electrophoresis of ca. 100,000, is composed of 961 amino acid residues and has a calculated molecular weight of 96,722. It is distinguished by a large number of 18-residue repeats in a region where mammalian fibrinogens have 13-residue repeats. The data are in accord with our previous finding that the lamprey alpha chain has a distinctive amino acid composition, almost half the residues being glycine, serine, or threonine. The chain differs from mammalian alpha chains in that there are no cysteines in the carboxy-terminal half, and thus no intrachain loop, nor are there any RGD sequences in the lamprey alpha chain. Taken together with previous data on the sequences of the beta and gamma chains, the findings bear significantly on our understanding of fibrin formation. The alpha chain also provides an interesting case of structural convergence during evolution.

Amino Acid Sequence↗
PubMed1989

The pattern of function-related regional cerebral blood flow investigated by single photon emission tomography with 99mTc-HMPAO in patients with presenile Alzheimer's disease and Korsakoff's psychosis.

Single photon emission tomography (SPET) with the lipophilic blood flow marker 99mTc-hexamethyl propyleneamine oxime (99mTc-HMPAO) has been used to determine regional uptake of radiolabel into brain regions of patients with presenile Alzheimer's disease and Korsakoff's psychosis, and age-matched controls. Using occipital cortical uptake as reference area, the pattern of relative regional cerebral blood flow (rCBF) was determined in other cortical areas and basal ganglia. In Alzheimer's disease, reduction in rCBF occurred most strikingly in posterior temporal and parietal areas. By contrast, in Korsakoff's psychosis, posterior temporal rCBF was maintained, although there was a trend to reduced tracer uptake in other cortical areas. These impairments of flow were correlated with impairments of neuropsychological function. In Alzheimer's disease, left posterior temporal and left parietal regions in particular showed rCBF to be strongly correlated with most aspects of cognitive function. In Korsakoff's psychosis, however, impaired flow in frontal regions was correlated with impaired performance on tests of memory and orientation. The findings in Alzheimer's disease show quantitative parallels with those from studies using Positron Emission Tomography (PET), and extend our understanding of the relationship between cognition and regional brain function in dementia. The findings in Korsakoff's psychosis offer the first direct evidence linking frontal lobe dysfunction with the cognitive impairment seen in the disorder.

Adult↗
PubMed1989

Effect of broadband noise on the human brain stem auditory evoked response.

The purpose of this paper is to describe the effect of broadband continuous noise on brain stem auditory evoked responses elicited from normal-hearing and hearing-impaired individuals. The motivation for this study derives from the increasing use of noise masking paradigms in diagnostic electrophysiology, the universal presence of background noise in everyday listening environments, and the frequent observation that background noise is more detrimental to the performance of the hearing-impaired individual than to the normal-hearing individual. Four studies were designed to evaluate: (1) the sensitivity and specificity of the latency-intensity series, (2) the sensitivity and specificity of the latency-noise series, (3) the dependence of the latency-noise series on signal-to-noise ratio near electrophysiologic threshold, and (4) the dependence of the latency-noise index on the signal level at which the test is performed. The results of the studies reported herein show that the electrophysiological response to increasing masker levels is more sensitive for identifying inner ear pathology than previously used latency-intensity series measures, without compromising specificity. It is suggested that simultaneous broadband masking should be considered as a test for localization of pathology in those subjects for whom routine behavioral measurements are not possible or when the results of such measurements are equivocal.

Adolescent↗
PubMed1989

Changes in cranial CSF volume during hypercapnia and hypocapnia.

Magnetic resonance imaging was used to measure the effect of inhalation of 7% CO2 and hyperventilation with 60% O2 on human cranial cerebrospinal fluid volume. During CO2 inhalation there was a reduction in the cranial CSF volume ranging from 0.7-23.7 ml (mean 9.36 ml). The degree of reduction in cranial CSF volume was independent of the individual subject's increase in end-expiratory pCO2 or mean arterial blood pressure, in response to hypercapnia. During hyperventilation with high concentration oxygen the cranial CSF volume increased in all subjects (range 0.7-26.7 ml, mean 12.7 ml). The mean changes in cranial CSF volume, induced by hypercapnia and hypocapnia, were very similar to the expected reciprocal changes in cerebral blood volume.

Adult↗
PubMed1988

Temporal physiochemical changes during in vitro relaxation time measurements: the cerebrospinal fluid.

Documented relaxation time measurements of body fluids such as cerebrospinal fluid (CSF) vary considerably. This may be largely due to lack of an appropriate method of maintaining the in vivo physiological and biochemical characteristics of the fluid. We have developed an in vitro technique that maintains the in vivo characteristics of body fluid samples for a sufficiently long period to establish the true relaxation times. To illustrate this we studied changes in CSF pH, pO2, and pCO2, first as it equilibrated with air and then under anaerobic conditions as found in vivo. Relaxation times of CSF were then studied under aerobic and anaerobic conditions. Under the particular aerobic conditions used the pH and pO2 of CSF increased quickly and pCO2 fell within the first 30 min. By 3-4 h equilibration with air was complete. The T1 and T2 relaxation times of CSF decreased by 14 and 16%, respectively, as a result of these physicochemical changes. It is important that such changes be considered when relaxation measurements of any body fluid are performed in vitro and efforts to maintain the in vivo milieu should not be neglected.

Aerobiosis↗
PubMed1988

Intracranial CSF volumes: natural variations and physiological changes measured by MRI.

Cranial CSF volumes, for the first time including CSF in the subarachnoid space, can be measured by Magnetic Resonance Imaging (MRI). The MRI sequence causes signal from the grey matter and white matter to cancel producing a contrast of 200: 1 between a unit of CSF and a unit of brain. We have assessed the variations between normal individuals and investigated some of the physiological factors that might influence cranial CSF volumes. Total CSF volumes were measured in 64 normal subjects, aged from 18-64 years (mean 38 years). Ventricular, cortical sulcal and posterior fossa volumes were also calculated separately. In 20 females with a normal menstrual cycle, CSF volumes were measured mid cycle and premenstrually; 10 post menopausal females and 10 males were rescanned after an interval of 2 weeks. Total cranial CSF volume were calculated before and during inhalation of 7% CO2 and before and during hyperventilation while breathing 60% O2, in 12 normal subjects. Total intracranial CSF volume ranged from 57.1-286.5 ml. Total intracranial and cortical sulcal CSF volumes increased more steeply with age than ventricular or posterior fossa CSF volumes. Males had more cranial CSF than females. Total CSF volume increased premenstrually in 19 females. Males and post-menopausal females did not have a significant change in CSF volume, on repeat examination. CO2 inhalation produced a mean increase of paCO2 of 17.2 mmHg and CSF volume decreased in all subjects (mean 9.4 ml). Cranial CSF volume increased in 11 subjects during O2 inhalation (range -0.5 to +26.7 ml mean 10.9 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Isolation and analysis of the gene encoding peripheral myelin protein zero.

We have isolated the gene encoding the Schwann cell glycoprotein P0, the major structural protein of the peripheral myelin sheath. In rats and mice, this gene is split into six exons distributed over 7 kb of DNA. The segregation of these exons is consistent with the functional segregation of the P0 protein into extracellular, membrane-spanning, and cytoplasmic domains. We find that the P0 extracellular domain is similar in structure to a single immunoglobulin variable region domain. In contrast to prototypical immunoglobulin domains, however, this P0 domain is encoded by two exons, the partitioning of which provides genetic evidence for the evolution of immunoglobulin-related domains from an ancestral half-domain. We also describe procedures for transfection of cultures of nontransformed rat Schwann cells and use these procedures to show that the Schwann cell-specific expression of the P0 gene is controlled by cis-acting elements localized upstream of exon I.

Amino Acid Sequence↗
PubMed1988

Magnetic resonance imaging in acute head injury.

Using cardiorespiratory monitoring and support equipment compatible with a low field (0.15 T) system, magnetic resonance imaging (MRI) of patients suffering acute head injuries proved to be both feasible and safe. An abnormality was demonstrated by magnetic resonance imaging in 46 of 50 patients examined within 7 days of head injury using T2 weighted (SE2200/80) and T1 weighted (IR2000/600/40) multislice sequences. IN contrast, computed tomography (CT) demonstrated abnormalities in only 31 of the 50 patients. Intracranial extracerebral space-occupying collections of blood were well shown by magnetic resonance imaging which provided especially clear definition in the posterior fossa, subtemporal and subfrontal regions. Magnetic resonance imaging was more sensitive to cerebral abnormalities associated with traumatic unconsciousness and detected parenchymal lesions both in patients in coma and in those who had lost consciousness for only a few minutes. Lesions seen with MRI but not with CT included non-haemorrhagic contusions and abnormalities thought to reflect shearing injuries of white matter and intracerebral vessels. Magnetic resonance imaging is an effective alternative to CT; the additional information it can provide should be valuable in increasing the understanding of the early effects and late consequences of a head injury.

Acute Disease↗