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Biomedical subjects

A Burgess

Publications and source records attributed to A Burgess.

At least 55 records · Page 3Linked to original sources
PubMed1993

Individual reliability of amplitude distribution in topographical mapping of EEG.

Whilst there is an accumulation of evidence suggesting that many quantitative EEG parameters show good stability and reliability, no previous study has considered whether the spatial distribution of EEG amplitude is reliable over time within a session. This study reports on the spatio-temporal reliability of EEG using data recorded from 24 subjects in a baseline condition with eyes open and also whilst performing a simple motor task. Both the internal stability and test-retest reliability for electrode parameters were comparable to previously published data. For most individuals, amplitude distribution was stable within each recording condition, but the test-retest reliability after 40 min was less good with the poorest reliability in the delta frequency band. Most subjects showed spatio-temporal reliability of less than 0.7 in at least one frequency band. In contrast, spatio-temporal reliability for the group average was good and exceeded 0.88 in all frequency bands. It is argued that the results indicate that reliability is insufficient to allow topographical comparisons for a single individual, but is more than adequate to allow group comparisons.

Adolescent↗
PubMed1993

The psychosocial impact of HIV infection in women.

The aim of the investigation was to study the prevalence of current and past psychiatric morbidity and psychosocial problems in HIV seropositive (HIV +ve) asymptomatic women. A cross-sectional controlled study including 57 HIV +ve women belonging to CDC group II and III (43 intravenous drug users and 14 non-IVDUs heterosexuals) and 23 HIV -ve women (15 intravenous drug users and 8 non-IVDUs heterosexuals) is reported. Outcome measures included, past psychiatric history, current psychological status (Zung Anxiety and Depression scales, Symptom Check List 90-Revised), Social Supports and Locus of Control Scales, and information on changes in work, social and sexual life after HIV testing. Results showed that HIV +ve women differed very little from HIV -ve controls regarding outcome measures and indeed for some variables HIV infected women had lower levels of psychological morbidity. Multiple regression analyses showed that alcohol misuse and a predominantly external locus of control accounted for the 29% of the variance of psychiatric distress (F = 9.23, p < 0.0006). The implications of the findings are discussed.

Adaptation, Psychological↗
PubMed1993

Neuropsychiatric aspects of HIV-1 infection in gay men: controlled investigation of psychiatric, neuropsychological and neurological status.

The aim of this study was to determine whether HIV infection is associated with psychiatric morbidity or neuropsychological impairment in asymptomatic and early symptomatic stages of disease in gay men. The subjects were 100 gay men (68 HIV-ve, 32 HIV+ve, 6 being CDC IV). All subjects were recruited at the time of requesting their first HIV test and the assessment was double-blind to HIV serostatus. There were no differences in psychiatric status or neuropsychological performance between the HIV-ve and HIV+ve groups. Multiple regression analysis and logistic regression were used to identify factors associated with psychiatric morbidity, neuropsychological impairment and subjective reporting of memory problems and physical symptoms for all 100 subjects. Previous psychiatric history and current illegal (non-dependent) drug use were associated with psychiatric morbidity, poor education was associated with neuropsychological impairment and psychiatric status (score on HAD and PSE) was associated with subjective reporting of memory problems and physical symptoms.

AIDS Dementia Complex↗
PubMed1993

The reliability and validity of two HIV-specific health-related Quality-of-Life measures: a preliminary analysis.

OBJECTIVE: To evaluate the reliability and validity of two HIV-specific Quality-of-Life (QoL) questionnaires in a UK sample. METHOD: Subjects were 99 HIV-seropositive gay men (23 were asymptomatic, 41 were asymptomatic, 35 had AIDS). QoL was measured using two HIV-specific QoL questionnaires. MEASURES: An adaptation of the Medical Outcomes Study questionnaire and a self-completion version of the Health-Related Quality-of-Life Questions. Affect was measured using the Hospital Anxiety and Depression (HAD) Scale. Disease measures included Centers for Disease Control and Prevention (CDC) stage, and CD4 and CD8 cell count. RESULTS: Both QoL instruments showed good internal reliability on all scales used. Many of the scales, particularly those related to physical health and functional performance, showed significant correlations with CD4 cell count and other measures of disease progression. Measures of physical health showed a deterioration in QoL as disease progressed from asymptomatic disease to AIDS. In contrast, most subscales purporting to measure psychological aspects of QoL did not correlate significantly with measures of disease progression, nor was there any difference between CDC stages. Subjects' global ratings of QoL were most strongly correlated with the HAD depression scale, although there were also significant correlations with most other QoL scales. CONCLUSION: This study provides further evidence for the reliability and validity of two HIV-specific QoL questionnaires in a wider range of disease stages than hitherto reported and raises issues relevant to the practical use of QoL scales in HIV disease.

CD4 Antigens↗
PubMed1992

The macroscopic, microscopic and spectrometric effects of various chemotherapeutic agents on the plasma-sprayed hydroxyapatite-coated implant surface.

The purpose of this research was to determine the nature of the residual hydroxyapatite (HA)-coated implant surface after treatment with various chemotherapeutic modalities, including: citric acid, chlorhexidine gluconate, hydrogen peroxide, tetracycline HCl, stannous fluoride, polymyxin B and a prototype plastic Cavitron tip. Implant surfaces were evaluated macroscopically, microscopically (scanning electron microscopy (SEM)) and spectrometrically (energy-dispersive spectrometry and X-ray diffraction). HA-substrate bond strength and dissolution testing was also performed for surfaces treated with a supersaturated citric acid solution. All treatments left either microscopic residues or a loss of surface roughness when viewed on SEM. A 30- to 60-s application of citric acid left a significantly greater coating thickness than all other treatments, whereas a 3-min application of citric acid removed significantly more HA than untreated controls. Significant changes in Ca/P ratios were seen with most treatments. The clinical significance of this phenomenon is not known. No treatments altered the crystallinity of the residual HA coating. A 1-min application of citric acid did not significantly alter the tensile bond strength of the coating to the substrate. The clinical significance of these findings is not known at present. However, when taken with results from previous studies, it appears that in treating the infected HA-coated implant surface, a 30- to 60-s application of citric acid (pH 1) may be beneficial in detoxifying the HA coating prior to regenerative procedures. Further in vitro and in vivo studies are necessary to evaluate the biological response to citric acid when used to detoxify the infected implant surface.

Analysis of Variance↗
PubMed1992

Rapid generation of region specific probes by chromosome microdissection and their application.

The strategy presented here to identify unequivocally cryptic chromosomal rearrangements has relevance to both prenatal and postnatal cytogenetic analysis as well as the analysis of tumour-associated chromosome rearrangements. Microdissection and in vitro amplification of specific chromosomal regions are performed, followed by labelling for fluorescent in situ hybridization (FISH) to normal metaphase chromosomes (Micro-FISH). Micro-FISH probes have been used successfully to determine the derivation of chromosome segments unidentifiable by standard chromosome banding analysis. Micro-FISH probes (created in less than 24 hours) now make it possible to identify explicitly the chromosome constitution of virtually all cytologically visible chromosome rearrangements.

Base Sequence↗
PubMed1992

Factor structure of the Wechsler Adult Intelligence Scale-revised (WAIS-R): a clinical sample.

Factor analysis was performed on a heterogeneous clinical sample of neurological patients. Both a two- and a three-factor model were extracted. The two-factor solution corresponded to Wechsler's categorization of verbal and performance subtests. The three-factor solution suggested a verbal comprehension factor, a perceptual organization and a third factor with highest loadings on digit span, arithmetic and digit symbol. Both models were consistent with factor models obtained from the standardization sample. As has previously been reported in neurologically impaired samples, the third factor was relatively more prominent than in the standardization sample. This study provides further evidence for the robustness of the WAIS-R factor structure across different populations and gives good support for the use of the WAIS-R in British clinical samples.

Adult↗
PubMed1992

Torsional stability of HA-coated and grit-blasted titanium dental implants.

Hydroxylapatite (HA)-coated and grit-blasted (non-HA-coated) titanium dental implants were inserted into healed extraction sites of canine mandibles. After six weeks, the animals were killed and the implants mechanically tested in torsion to failure. Interface attachment strength, implant/tissue compatibility, integrity of the HA coating, and the location of interface failure were evaluated. Mechanical testing demonstrated an interface torsional strength of 3.98 +/- 0.93 MPa for the HA-coated implants and 2.25 +/- 0.65 MPa for the grit-blasted implants. This represents a 76.9% improvement in the maximum torsional interface strength, and is statistically-significant (p = 0.0004). On qualitative histologic analysis, interface failure was seen to occur primarily at the HA/implant interface, although failure through the HA coating and regions of bone/HA interface failure were observed. The HA-coated implants had bone in direct apposition to their surface with no fibrous tissue interposition. The grit-blasted implants also had regions of direct bone-implant apposition, but these areas were limited to a smaller proportion of the total interface area. There was no evidence of breakdown or change in thickness of the HA coating.

Animals↗
PubMed1991

Fine-needle aspiration biopsy diagnosis of malignant rhabdoid tumor of the kidney.

A series of six fine-needle aspiration biopsies from three patients with malignant rhabdoid tumor of the kidney is reviewed. The smears revealed round, polygonal, and irregularly shaped cells with large nuclei and prominent nucleoli. Some of the tumor cells contained light pink to purple cytoplasmic inclusions that correlated with the eosinophilic inclusions seen in histopathologic sections and filamentous cytoplasmic aggregates noted on ultrastructural examination. Diagnosis of malignant rhabdoid tumor of the kidney may be suggested from aspiration biopsy smears; however, further confirmation of the diagnosis by histologic or ultrastructural examination is desirable.

Biopsy, Needle↗
PubMed1991

Role of testicular fine-needle aspiration biopsy in the evaluation of male infertility: cytologic and histologic correlation.

A series of testicular fine-needle aspiration biopsy specimens from 272 infertile men with azoospermia were reviewed and categorized according to morphologic patterns. These included active spermatogenesis, 14 (5%); hypospermatogenesis, 106 (39%); Sertoli cells only, 70 (26%); atrophic pattern, 52 (19%); and maturation arrest, 1 (0.36%). In 29 cases (11%) the amount of material was insufficient for evaluation. The histologic and cytologic findings in 52 cases showing spermatogenesis correlated very well in 52 cases for which open testicular biopsy specimens were also available. These findings indicate that fine-needle aspiration biopsy of the testis is a reliable and useful technique for the investigation of patients with azospermia.

Adult↗
PubMed1991

Fine-needle aspiration biopsy (FNAB) diagnosis of testicular involvement in acute lymphoblastic leukemia in children.

A series of 106 fine-needle aspiration biopsy specimens obtained from the testes of children with acute lymphoblastic leukemia was reviewed retrospectively. Involvement by leukemia was seen in 34, there was no evidence of disease in 52, and the cellular sample was inadequate in 20. All aspiration smears, except those with leukemic involvement, showed a variable number of Sertoli cells. Testicular leukemia was diagnosed by the presence of numerous leukemic cells and rare or no Sertoli cells. Fine-needle aspiration biopsy is a simple but effective technique for diagnosing leukemic involvement of the testis in children with acute lymphoblastic leukemia.

Biopsy, Needle↗
PubMed1991

Neuroscience of HIV infection: basic and clinical frontiers.

Whilst this conference presented no new or exciting breakthroughs in our understanding of the psychosocial or neuropsychological aspects of HIV disease, there were some useful contributions to our knowledge in these areas. Previous work suggesting that HIV seropositive individuals with HIV are no more likely to suffer poor psychosocial adjustment than matched HIV-controls. However, where psychiatric disorders are seen, the most common are adjustment disorders followed by drug and alcohol abuse. Mania, whilst quite rare, may be more commonly seen with HIV than should be expected. People with asymptomatic HIV infection appear to be no more likely to show a cognitive deficit than matched HIV-individuals and this appears to be equally true for gay men, intra-venous drug users and people with haemophilia. However, as the disease progresses, neuropsychological impairment, or even dementia, may be seen and when this occurs the pattern of decline appears to be precipitous rather than insidious.

AIDS Dementia Complex↗
PubMed1991

Profile analysis of the Wechsler intelligence scales: a new index of subtest scatter.

A statistical method of profile analysis originally suggested by Huba (1985, 1986), the Mahalanobis distance, D2, is described and discussed with reference to its use with the Wechsler scales. Examples are given to illustrate the properties of D2 and two BASIC computer programs are presented that will calculate D2; one for the WAIS-R and the other which can be readily adapted to the test selection of the user's choice. It is argued that D2 is a useful addition to existing methods of statistical analysis of the Wechsler scales.

Analysis of Variance↗
PubMed1990

Effects of cooling rate and glycerol concentration on the structure of the frozen kidney: assessment by cryo-scanning electron microscopy.

An experimental technique, employing a directional solidification stage for controlled freezing of tissue samples and low-temperature scanning electron microscopy for observation of the structure of the frozen-hydrated samples, was used to study freezing processes in the kidney. Parametric studies in which the cooling rate during freezing and the concentration of glycerol in the tissue were varied confirmed the results of earlier freeze-substitution studies. The results suggest a mechanism for ice propagation in the kidney similar to that already proposed for the liver, in which ice originates in, and is subsequently propagated through, the peritubular vasculature. The ice front dehydrates the cells and tubular structures encountered in its path, thus preventing intraluminal freezing. At higher rates of cooling and increased concentrations of glycerol there is less dehydration of cortical structure and intraluminal freezing occurs.

Animals↗