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Biomedical subjects

M Jackson

Publications and source records attributed to M Jackson.

At least 163 records · Page 9Linked to original sources
PubMed1996

Behavioral descriptors that differentiate between seizure and nonseizure events in a pediatric population.

The diagnosis and treatment of epilepsy relies heavily on descriptions of behavioral changes noted during seizure episodes. A pilot study was completed to determine the frequency of occurrence of behaviors commonly associated with seizures in a pediatric population (n = 153). Caretakers of the children (ages = 4 months to 19 years) were asked to respond to a checklist containing 40 behavioral descriptors. Thirteen descriptors were found to differentiate between seizure and nonseizure events. Twelve of these behaviors were endorsed significantly more frequently by caretakers of children with seizures including the following: does not remember what happened, moves mouth funny, drools, jerking/twitching, becomes stiff, changes in breathing, stares off, bites or chews tongue, eyes look glassy, will not respond, mumbles or slurs words, and eyes or head turn to one side. One behavior, fidgets in seat, was significantly more associated with nonseizure episodes. The behavioral descriptors may be presented in a checklist format or incorporated within a clinical interview in primary care settings for initial screening of children with possible seizure disorders.

Adolescent↗
PubMed1996

Dibefurin, a novel fungal metabolite inhibiting calcineurin phosphatase activity.

The novel calcineurin inhibitor, dibefurin, has been isolated from the fungal culture AB 1650I-759. The isolation was bioactivity-directed fractionation using an assay which measures the phosphatase activity of calcineurin. The compound was purified by countercurrent, reverse phase and gel filtration chromatographies. Several studies, including crystallographic, NMR and MS, revealed that dibefurin is a novel dimeric compound of a unique structural type.

Benzofurans↗
PubMed1996

Novel triterpene sulfates from Fusarium compactum using a rhinovirus 3C protease inhibitor screen.

Two novel triterpene sulfates have been isolated from Fusarium compactum by bioactivity-directed fractionation using an assay which measures the inhibition of proteolytic activity of rhinovirus 3C protease on a fluorogenic peptide substrate. The compounds were purified by countercurrent and reverse phase chromatographies. NMR, MS, UV and IR studies revealed two triterpene sulfates, uncommon metabolites of terrestrial fungi.

Cholestenes↗
PubMed1996

Development of food frequency questionnaires in three population samples of African origin from Cameroon, Jamaica and Caribbean migrants to the UK.

OBJECTIVES: To develop the methods for assessment of food and nutrient intake using standardized food frequency questionnaires (FFQ) in three African origin populations from Cameroon, Jamaica and Caribbean migrants to the United Kingdom. DESIGN: Cross-sectional assessment of diet from a representative sample in each site, using either a 2-day food diary or a 24-h recall method to determine foods for inclusion on the food frequency questionnaire. SETTING: A rural and urban site in Cameroon, Evodoula and Cite Verte in Yaounde, respectively; a district in Kingston Jamaica; African-Caribbeans living in central Manchester, UK. SUBJECTS: Aged 25-79 years, 61 from the Cameroonian urban site, 62 from the village site; 102 subjects from Jamaica (additional analysis on a subsample of 20): 29 subjects from Manchester, UK. MAIN OUTCOME MEASURES: Foods contributing to nutrients in each site to allow the development of a FFQ. RESULTS: A high response rate was obtained in each site. Comparison of macronutrient intakes between the sites showed that carbohydrate was the most important contributor to energy intake in Jamaica (55%) and the least in rural Cameroon. In rural Cameroon, fat (mainly palm oil) was the most important contributor to energy intake (44%). Manchester had the highest contribution of protein to energy (17%). Foods contributing to total energy, protein, fat and carbohydrate were determined. In rural Cameroon, the top 10 food items contributed 66% of the total energy intake compared to 37% for the top 10 foods in Manchester. Foods contributing to energy were similar in Jamaica and Manchester. Cassava contributed 44% of the carbohydrate intake in rural Cameroon and only 6% in urban Cameroon. One FFQ has been developed for use in both sites in Cameroon containing 76 food items. The FFQ for Jamaica contains 69 foods and for Manchester 108 food items. CONCLUSION: Considerable variations exist within sites (Cameroon) and between sites in foods which are important contributors to nutrient intakes. With careful exploration of eating habits it has been possible to develop standardized, but locally appropriate FFQs for use in African populations in different countries.

Adult↗
PubMed1995

A precision cranial immobilization system for conformal stereotactic fractionated radiation therapy.

PURPOSE: Conformal radiotherapy has been shown to benefit from precision alignment of patient target to therapy beam (1, 6, 13). This work describes an optimized immobilization system for the fractionated treatment of intracranial targets. A study of patient motion demonstrates the high degree of immobilization which is available. METHODS AND MATERIALS: A system using dental fixation and a thermoplastic mask that relocates on a rigid frame is described. The design permits scanning studies using computed tomography (CT) and magnetic resonance imaging (MR), conventional photon radiotherapy, and high precision stereotactic proton radiotherapy to be performed with minimal repositioning variation. Studies of both intratreatment motion and daily setup reliability are performed on patients under treatment for paranasal sinus carcinoma. Multiple radiographs taken during single treatments provide the basis for a three-dimensional (3D) motion analysis. Additionally, studies of orthogonal radiographs used to setup for proton treatments and verification port films from photon treatments are used to establish day to day patient position variation in routine use. RESULTS: Net 3D patient motion during any treatment is measured to be 0.9 +/- 0.4 mm [mean +/- standard deviation (SD)] and rotation about any body axis is 0.14 +/- 0.67 degrees (mean +/- SD). Day-to-day setup accuracy to laser marks is limited to 2.3 mm (mean) systematic error and 1.6 mm (mean) random error. CONCLUSION: We conclude that the most stringent immobilization requirements of 3D conformal radiotherapy adjacent to critical normal structures can be met with a high precision system such as the one described here. Without the use of pretreatment verification, additional developments in machine and couch design are needed to assure that patient repositioning accuracy is comparable to the best level of patient immobility achievable.

Brain Neoplasms↗
PubMed1995

Protein folding intermediates with rapidly exchangeable amide protons contain authentic hydrogen-bonded secondary structures.

Recent studies on protein folding intermediates by pulsed amide proton exchange and by far-ultraviolet circular dichroism have shown important discrepancies between the secondary structure contents estimated by these two methods at early folding stages. To solve these apparent discrepancies, structural studies have been performed on the isolated, 101 residue long, C-terminal proteolytic domain (F2) of the Escherichia coli tryptophan synthase beta chain, which had previously been reported to behave as an early folding intermediate [Chaffotte, A. F., Cadieux, C., Guillou, Y., & Goldberg, M. E. (1992) Biochemistry 31, 4303-4308]. The secondary structure of F2 has been investigated by far-UV circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, and NMR. The CD and FTIR spectra clearly indicate that isolated F2 has about 30-45% of its residues involved in secondary structures stabilized by conventional hydrogen bonds. The characteristics of the NMR spectrum (line broadening, absence of structure-induced chemical shifts, absence of nuclear Overhauser effects in the amide region, few dipolar interactions between the side-chain protons) suggest that isolated F2 is oscillating between several conformations in rapid equilibrium. The rate of amide proton exchange has been studied by one-dimensional NMR, which indicates a significant extent of proton protection, with, however, protection factors that can be estimated to be at most 60 and more probably closer to 10. Thus, F2 appears to exist as a molten globule that exhibits very low amide proton protection and yet contains a large fraction of its residues involved in authentic secondary structures stabilized by hydrogen bonds. Such a state is likely to correspond to the earliest structured folding intermediates thus far characterized.

Amides↗
PubMed1995

Beware of connective tissue proteins: assignment and implications of collagen absorptions in infrared spectra of human tissues.

Infrared spectra of human central nervous system tissue and human breast carcinoma are presented. The spectra are discussed in terms of the composition of the tissues. It is shown that differences between spectra of white and grey matter can be rationalised on the basis of differences in lipid content. Spectra of the choroid plexus and arachnoid villus of the meninges show a series of absorptions not observed in other CNS tissue. These absorptions are discussed in terms of the connective tissue content of the samples. We demonstrate that the presence of collagen results in the appearance of a series of characteristic absorptions which may be mis-assigned as DNA phosphate absorptions. The implications of the presence of collagen in tissues for the diagnosis of disease states by IR spectroscopic methods, with particular reference to cancer, is discussed.

Brain Chemistry↗
PubMed1995

Tau, ubiquitin, and alpha B-crystallin immunohistochemistry define the principal causes of degenerative frontotemporal dementia.

OBJECTIVE: We investigated the use of immunostaining with antibodies to tau, ubiquitin, and alpha B-crystallin in defining a protocol for the staged neuropathologic examination of brains from patients with a progressive frontotemporal dementia. DESIGN: Brains obtained from 50 patients dying with the clinical diagnosis of frontotemporal dementia were examined histopathologically to define pathologic distinctions. SETTING: Two university hospital neuropathology departments. RESULTS: Anti-tau immunostaining defined corticobasal degeneration, Alzheimer's disease, and Pick's disease; antiubiquitin defined motor neuron disease with dementia. The remaining brains have frontal lobe degeneration: the use of alpha B-crystallin immunostaining, on these, to detect ballooned neurons may help to define two groups of patients, one of which we believe may represent a variant of Pick's disease. CONCLUSION: These findings indicate that immunostaining with these antibodies is essential for the evaluation of frontal dementia.

Antibodies↗
PubMed1995

Chronic L-DOPA administration induces dyskinesias in the 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine-treated common marmoset (Callithrix Jacchus).

Dyskinesias occur in the majority of patients with Parkinson's disease chronically treated with L-DOPA and also occur in several nonhuman primate species after 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP) and L-DOPA treatment. The common marmoset (Callithrix jacchus) shows parkinsonian motor deficits after MPTP administration, and we now report dyskinesias occurring in this species during chronic L-DOPA exposure. Marmosets rendered chronically parkinsonian after MPTP administration were treated orally with L-DOPA plus carbidopa for 3 weeks. After several days the animals began to display chorea, choreoathetosis, and dystonia. The severity of dyskinesias varied between the animals, with the most severely parkinsonian animals displaying the most dyskinetic movements. Each animal showed an idiosyncratic pattern of dyskinesias, which was highly reproducible. These L-DOPA-primed animals also received other D2 D1, and mixed D1/D2 agonist drugs. Quinpirole, bromocriptine, pergolide, apomorphine, and A-77636 all produce dyskinesias that were identical in character to those seen after L-DOPA administration, but the D1 agonist A-77636 gradually abolished dyskinesias while preserving its antiparkinsonian activity. The MPTP-treated marmoset provides a useful model in which to study dyskinesias in Parkinson's disease and to examine new therapeutic strategies aimed at alleviating this common side effect of chronic dopamine replacement therapy.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1995

A redrawn Vandenberg and Kuse mental rotations test: different versions and factors that affect performance.

The available versions of the Vandenberg and Kuse (1978) Mental Rotations Test (MRT) have physically deteriorated because only copies of copies are available. We report results from a redrawn version of the MRT and for alternate versions of the test. Males perform better than females, and students drawn from the physical sciences perform better than students drawn from the social sciences and humanities, confirming other reports with the original version of the MRT. Subjects find it very hard to perform the MRT when stimuli require rotation along both the top/bottom axis and the left/right axis. The magnitude of effect sizes for sex (which account, on average, for some 20% of the variance) does not increase with increasing difficulty of the task. Minimal strategy effects were observed and females did not perform differently during the menstrual period as opposed to the days between the menstrual periods. Practice effects are dramatic, confirming other reports with the original MRT, and can also be shown to be powerful in a transfer for practice paradigm, where test and retest involve different versions of the MRT. Main effects of handedness on MRT performance were not found.

Adult↗
PubMed1995

Arthritis diagnosis based upon the near-infrared spectrum of synovial fluid.

Synovial fluid aspirates have been characterized by measuring their visible/near-infrared spectra (400-2500 nm). The hypothesis tested in this study is that the spectra contain sufficient information to serve as an aid in the diagnosis and/or staging of arthritic disorders. The concentrations of all major constituents are carried implicitly in the spectra, and in this sense this approach is similar in spirit to conventional synovial fluid analysis. The distinguishing feature of this method is that we have not converted the raw data (spectra) explicitly to analytical information. Rather, we have used automated pattern recognition methods to identify significant characteristics of the spectra themselves. A total of 109 spectra were measured and split into three classes according to the disease (osteoarthritis, rheumatoid arthritis, or spondyloarthropathy) affecting the patient from whom the synovial fluid sample was taken. An automated classification method was then trained by correlating features derived from these spectra to the clinical diagnoses. The robustness of the classification was validated using the leave-one-out cross-validation method, i.e., by training on all but one of the spectra and using the resulting model to predict the classification for the spectrum that is left out. The result derived by following this procedure for each of the spectra was that 105 of the 109 predicted classifications correctly matched the clinical diagnosis. These results suggest that the near-infrared spectrum of synovial fluid is sufficient to allow diagnosis of the disease affecting the joint from which the aspirate is drawn.

Arthritis, Rheumatoid↗
PubMed1995

Univentricular heart with systemic outflow obstruction: palliation by primary Damus procedure.

In 24 consecutive infants (19 male and 5 female) with complex forms of single-ventricle physiology and systemic outflow obstruction, a modified Damus operation without the use of exogenous material was undertaken in conjunction with creation of an aortopulmonary shunt 3.5 mm in diameter. The median age at operation was 6 days (range, 1 to 170 days) and the median weight, 3.4 kg (range, 2.6 to 4.6 kg). There were nine early deaths. All 15 survivors (median follow-up, 6.5 months) were clinically well without major systemic ventricular dysfunction or atrioventricular or arterial valve regurgitation. Ten of them have undergone a superior vena cava-pulmonary shunt (one death), and 1 has required patch angioplasty of the aortic arch and innominate artery with revision of the aortopulmonary shunt. The 4 other survivors are awaiting a cavopulmonary shunt. Univariate analysis yielded the chronologic rank for an individual procedure (higher risk of death early in the series), presence of aortic arch atresia, and presence or absence of transposition of the great arteries as predictors of death. This aggressive surgical approach provides excellent early palliation, and because the operation prevents abnormal ventricular hypertrophy from pressure or volume overload, systemic ventricular function is optimally conserved for a future Fontan-type procedure.

Cardiac Surgical Procedures↗
PubMed1995

The dynamic condylar screw in the management of subtrochanteric fractures of the femur.

We reviewed 43 patients with subtrochanteric fractures treated with the AO dynamic condylar screw (DCS) to determine the medical and technical complication rate. Seven patients died before union and nine sustained major medical complications. Thirty fractures united without event. There were six technical failures, three related to failure of the medial buttress. The DCS can be used successfully in most subtrochanteric fractures, although there is a considerable complication rate, which reflects the general condition of the patient and the biomechanics of the proximal femur.

Adult↗