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Biomedical subjects

C Graham

Publications and source records attributed to C Graham.

At least 73 records · Page 4Linked to original sources
PubMed1999

Human sleep in 60 Hz magnetic fields.

This report describes a double-blind, laboratory-based study of 24 healthy young men in which sufficient data were collected to examine the effects of intermittent versus continuous exposure to a 60 Hz, 28.3 microT magnetic field on multiple EEG measures of night sleep. Intermittent, but not continuous or sham exposure, was associated with less total sleep time, reduced sleep efficiency, increased time in Stage II sleep, and decreased REM sleep. Subjects exposed intermittently to the field also reported sleeping less well and feeling less rested in the morning than subjects in the other two groups. All observed effects were significant at P < or = .04 or less. The public health relevance of these results cannot be assessed as yet. Poor sleep quality, however, can have a detrimental influence on worker safety and performance, and has been associated with decrements in memory and learning processes. Additional research appears warranted.

Adolescent↗
PubMed1999

Human exposure to 60-Hz magnetic fields: neurophysiological effects.

The neurophysiological effects of exposure to power-frequency magnetic fields at two occupationally-relevant intensities were evaluated in a single-blind study with 18 male and 18 female volunteers. Auditory brainstem (BAEP) and somatosensory (SEP) evoked potentials were recorded before, during and after field exposure (duration = 45 min, frequency = 60 Hz, field intensities = 14.1 or 28.3 microtesla, microT), or an equivalent sham-exposure control period. Visual event-related potentials (VEP) to pattern reversal stimuli were also recorded before and after the exposure period. Field exposure had no differential effects on the BAEP, the VEP, or on SEP measures of central conduction time. Men and women showed a similar lack of sensitivity to exposure. The present results do not support the mechanistic hypothesis that the transmission of sensory information to appropriate cortical centers is delayed or distorted by exposure to power-frequency magnetic fields at occupational intensities.

Adolescent↗
PubMed1999

Self-report of circadian type reflects the phase of the melatonin rhythm.

This study examined the relationship between circadian rhythm characteristics of the pineal hormone melatonin and individual differences in circadian type and mood. 95 healthy young men and 22 women were assessed each hour (00:00-07:00 h) for blood levels of melatonin throughout one night in the laboratory. Each subject was assessed for circadian type (morning, afternoon, or evening type) and morning mood (PANAS). Circadian type was strongly related to the melatonin acrophase but not to amplitude or time of year of assessment. Also, morning types evidenced a more rapid decline in melatonin levels after the peak than did evening types. Evening types were younger than were morning types. Female morning types reported more positive affect upon waking than did female afternoon or evening types. Males showed no such discrimination. Age was related to both melatonin acrophase and circadian type but did not explain the relationship between them. The results replicate and extend findings on circadian type and psychological and physiological variables.

Adolescent↗
PubMed1999

Measles inclusion-body encephalitis caused by the vaccine strain of measles virus.

We report a case of measles inclusion-body encephalitis (MIBE) occurring in an apparently healthy 21-month-old boy 8.5 months after measles-mumps-rubella vaccination. He had no prior evidence of immune deficiency and no history of measles exposure or clinical disease. During hospitalization, a primary immunodeficiency characterized by a profoundly depressed CD8 cell count and dysgammaglobulinemia was demonstrated. A brain biopsy revealed histopathologic features consistent with MIBE, and measles antigens were detected by immunohistochemical staining. Electron microscopy revealed inclusions characteristic of paramyxovirus nucleocapsids within neurons, oligodendroglia, and astrocytes. The presence of measles virus in the brain tissue was confirmed by reverse transcription polymerase chain reaction. The nucleotide sequence in the nucleoprotein and fusion gene regions was identical to that of the Moraten and Schwarz vaccine strains; the fusion gene differed from known genotype A wild-type viruses.

Encephalitis, Viral↗
PubMed1999

Effective dose equivalent due to gamma-ray emissions from hot particles.

The quantification of dose from hot particles in the nuclear power industry has received a good deal of attention in the past few years. Specifically, calculational models have been developed to determine shallow dose equivalent from both beta and gamma-rays (using VARSKIN) and to estimate deep dose equivalent based upon the gamma dose at a tissue depth of 1 cm. These two values are reported for regulatory purposes. The purpose of this study is to estimate another measure of dose from hot particles (or from skin contamination over a small area), specifically the effective dose equivalent which takes into account all organs of the body receiving appreciable dose from the gamma-ray emissions from the contamination. While it is generally recognized that this dose will be small, this study gives representative doses for a range of hot particle locations and gamma-ray energies. MCNP and the ADAM phantom have been used for the calculational model. The effective dose equivalent is found to range from 0.1 to 12 microSv h(-1) MBq(-1) (0.4 to 43 microrems h(-1) microCi(-1)) of gamma activity, depending upon the location of the hot particle on the body.

Dose-Response Relationship, Radiation↗
PubMed1999

Domain exchange experiments in duck delta-crystallins: functional and evolutionary implications.

Delta-crystallin, the major soluble protein component of the avian and reptilian eye lens, is homologous to the urea cycle enzyme argininosuccinate lyase (ASL). In duck lenses there are two delta crystallins, denoted delta1 and delta2. Duck delta2 is both a major structural protein of the lens and also the duck orthologue of ASL, an example of gene recruitment. Although 94% identical to delta2/ASL in the amino acid sequence, delta1 is enzymatically inactive. A series of hybrid proteins have been constructed to assess the role of each structural domain in the enzymatic mechanism. Five chimeras--221, 122, 121, 211, and 112, where the three numbers correspond to the three structural domains and the value of 1 or 2 represents the protein of origin, delta1 or delta2, respectively--were constructed and thermodynamically and kinetically analyzed. The kinetic analysis indicates that only domain 1 is crucial for restoring ASL activity to delta1 crystallin, and that amino acid substitutions in domain 2 may play a role in substrate binding. These results confirm the hypothesis that only one domain, domain 1, is responsible for the loss of catalytic activity in delta1. The thermodynamic characterization of human ASL (hASL) and duck delta1 and delta2 indicate that delta crystallins are slightly less stable than hASL, with the delta1 being the least stable. The deltaGs of unfolding are 57.25, 63.13, and 70.71 kcal mol(-1) for delta1, delta2, and hASL, respectively. This result was unexpected, and we speculate that delta crystallins have adapted to their structural role by adopting a slightly less stable conformation that might allow for enhanced protein-protein and protein-solvent interactions.

Amino Acid Sequence↗
PubMed1999

The role of psychological and biological factors in postinfective gut dysfunction.

BACKGROUND: Both psychological and physiological disturbances have been implicated in the aetiopathogenesis of irritable bowel syndrome (IBS). AIMS: To investigate how the psychological factors act, and the involvement of infective and physiological factors. METHODS: Consecutive patients hospitalised for gastroenteritis reported life events for the previous 12 months, and past illness experiences on standardised questionnaires. They also completed psychometric questionnaires for anxiety, neuroticism, somatisation, and hypochondriasis. In some patients, rectal biopsy specimens were obtained during the acute illness and at three months postinfection. RESULTS: Ninety four patients completed all questionnaires: 22 patients were diagnosed with IBS after their gastroenteritis (IBS+), and 72 patients returned to normal bowel habits (IBS-). IBS+ patients reported more life events and had higher hypochondriasis scores than IBS- patients. The predictive value of the life event and hypochondriasis measures was highly significant and independent of anxiety, neuroticism, and somatisation scores, which were also elevated in IBS+ patients. Rectal biopsy specimens from 29 patients showed a chronic inflammatory response in both IBS+ and IBS- patients. Three months later, specimens from IBS+ patients continued to show increased chronic inflammatory cell counts but those from IBS- patients had returned to normal levels. IBS+ and IBS- patients exhibited rectal hypersensitivity and hyper-reactivity and rapid colonic transit compared with normal controls, but there were no significant differences between IBS+ and IBS- patients for these physiological measurements. CONCLUSION: Psychological factors most clearly predict the development of IBS symptoms after gastroenteritis but biological mechanisms also contribute towards the expression of symptoms.

Adolescent↗
PubMed1999

Relationship between allergic contact dermatitis and electrophilicity.

To evaluate the role of electrophilicity in the induction of allergic contact dermatitis (ACD) in humans, we compared the structure-activity relationship (SAR) model of ACD with those of electrophilic and nonelectrophilic subsets of chemicals in the ACD database. For these analyses, electrophilicity was defined as the potential of a chemical to induce mutations in Salmonella. It was found that electrophilicity accounted for approximately 30-40% of ACD-inducing ability, and the remainder was associated with nonelectrophilic structures. The identification of these moieties opens the possibility for studying their role in ACD.

Algorithms↗
PubMed1999

Using an annual over-75 health check to screen for depression: validation of the short Geriatric Depression Scale (GDS15) within general practice.

OBJECTIVE: To validate the short Geriatric Depression Scale (GDS15) as a screening instrument and determine the optimal cutpoint for detecting depression among older people living in the community. DESIGN: Two stage study with the first stage consisting of a health check of people aged 75 years and over by a practice nurse which included the GDS15. A second-stage diagnostic interview including the criterion standard was carried out blind to GDS15 score. SETTING: A large general practice in Melton Mowbray, Leicestershire, UK. PATIENTS: A random sample (stratified according to first-stage GDS15 score) of 257 older people living in the community, without significant cognitive impairment, were selected for the second-stage diagnostic interview. MEASURES: The first-stage GDS15 score was compared with diagnostic status for depression and anxiety disorders (according to ICD-10 criteria) and presence of depressive symptoms at the second-stage clinical interview. RESULTS: Ninety-three per cent of those eligible for the study were successfully screened with the GDS15. A cutpoint of <3/3+ had a sensitivity of 100% and specificity of 72% in detecting cases of depression but fewer than one in five of those testing positive reached a diagnostic threshold. Only 25% of those with a diagnosis of depression had any mention of mental health problems in their medical notes in the year prior to the clinical interview. For detecting depressive symptoms the same cutpoint was 79% sensitive and 78% specific with a positive predictive value of 46%. CONCLUSIONS: Used as part of an annual over-75 health check in primary care, the GDS15 would detect a significant amount of hidden morbidity which would serve the original purpose of the annual elderly health checks in the UK.

Aged↗
PubMed1999

Rapid identification of Mycobacterium bovis BCG by the detection of the RD1 deletion using a multiplex PCR technique.

The BCG vaccine strain cannot, with confidence, be differentiated from other members of the Mycobacterium tuberculosis complex on phenotypic tests alone. Isolates from clinical sites not associated with vaccination may be confused with M. tuberculosis. A characteristic of BCG strains is the deletion of the genomic region RD1; detection of this forms the basis of a multiplex polymerase chain reaction (PCR) assay to distinguish BCG strains. In this study, 28 M. tuberculosis complex strains were analysed by the PCR assay. A DNA sequence displaying the characteristic deletion was detected in all eleven of the BCG strains tested and was not found in representatives of other members of the complex, including M. bovis. Thus, the assay affords a rapid, simple and effective method for the discrimination of the BCG vaccine strain from other members of the M. tuberculosis complex.

BCG Vaccine↗
PubMed1998

Investigation of vesicular rashes for HSV and VZV by PCR.

Vesicular fluid from rashes of 132 patients was tested by a multiplex PCR shown to be specific for herpes simplex virus (HSV) type 1 and 2, and varicella zoster virus (VZV) genomic DNA. The results were compared with those obtained by examination by electron microscopy and virus isolation by cell culture. The PCR did not differentiate between HSV 1 and 2. By PCR, 64 HSV infections and 53 VZV infections were identified, with presumed 100% sensitivity and specificity. Fifteen specimens tested negative by PCR, electron microscopy, and virus isolation for herpes viruses. The sensitivities of virus isolation and electron microscopy for detection of herpes simplex virus were 56% and 80%. For varicella zoster virus, the sensitivities of virus isolation and electron microscopy were 47% and 60%. These data illustrate the advantage of rapid PCR diagnosis of herpes simplex virus and varicella zoster virus in vesicle fluids.

Adolescent↗
PubMed1998

Changes in pulmonary mechanics after lung volume reduction surgery.

Lung volume reduction surgery (LVRS) is a promising new treatment for emphysema and leads to increased flow rates. We investigated the mechanisms by which flow rates could increase and the correlates of lessened dyspnea in patients undergoing LVRS before and 3 months after LVRS in patients with severe emphysema. The following were done: routine pulmonary function testing, measurements of elastic recoil (Pel), tidal breathing patterns, inspiratory work of breathing (Winsp), construction of static recoil-maximum flow curves, and measurement of baseline and transitional dyspnea index (TDI). There were increases in forced vital capacity (FVC: 2.24 +/- 0.71 to 2.92 +/- 0.63 liters; p < 0.05), forced expired volume in 1 (FEV1: 0.64 +/- .16 to 1.03 +/- 0.28 liters; p < 0.01), and decreases in all divisions of lung volume, e.g. total lung capacity (TLC: 6.86 +/- 1.41 to 5.96 +/- 1.49 liters; p < 0.01). Maximum Pel increased (11.7 +/- 3.7 to 19.8 +/- 7.8 cmH2O; p < 0.02) as did the coefficient of retraction (CR = Pel/TLC: 1.8 +/- 0.7 to 3.6 +/- 3.6 +/- 2.2 cmH2O/liter). However, the individual responses in other parameters were markedly different among patients. There was no consistent trend in changes in the slope or position of the static recoil-maximum flow curve or Winsp. The only positive correlate of improved dyspnea (TDI = 3.22 +/- 2.22; p < 0.01) was improvement in CR, FEV1 being a weak negative correlate and change in lung volume not being a correlate at all. We conclude that there is a heterogeneous response of the airways to LVRS. Increased elastic recoil was the primary determinant of improved flow rates after LVRS and is the only positive correlate for improvement in dyspnea.

Aged↗
PubMed1998

Cloning and tissue expression of the mouse ortholog of AIM1, a betagamma-crystallin superfamily member.

We report the isolation of the murine ortholog of AIM1, a human gene whose expression is associated with the reversal of tumorigenicity in an experimental model of melanoma. Mouse and human AIM1 are more than 90% identical in amino acid sequence in the betagamma-crystallin repeats and the C-terminal domain, and more than 75% identical in the extended N-terminal domain. Consistent with the isolated cDNA representing the authentic AIM1 ortholog, linkage analysis localized mouse Aim1 to proximal mouse Chromosome (Chr) 10 in a conserved linkage group with genes localized to human Chr band 6q21. Searches of EST databases identified a second AIM1-like gene in both mouse and human, suggesting the existence of a gene family. Northern analysis demonstrates Aim1 is expressed most abundantly in adult skin, lung, heart, liver, and kidney and is temporally regulated during embryogenesis. Aim1 is expressed highly in the shaft region of the hair follicles and the presumptive ectoderm, but not at detectable levels in melanocytes or melanocyte precursor cells.

Amino Acid Sequence↗
PubMed1998

Immunologic cross-reactivity between respiratory chemical sensitizers: reactive dyes and cyanuric chloride.

BACKGROUND: CyCl is a low molecular weight reactive chemical used as an intermediate in the production of plastics, herbicides, pharmaceuticals, and fiber-reactive dyes. It is a potent inducer of specific IgE antibody. The CyCl functionality is a structural component of monochlorotriazine and dichlorotriazine dyes. OBJECTIVE: We have investigated the immunologic cross-reactivity between cyanuric chloride (CyCl) and reactive dyes and it was hypothesized that this moiety might be a dye epitope and that it might stimulate an allergic antibody response in dye-exposed workers. METHODS: To test this hypothesis, we have used sera with IgE antibodies to CyCl and also sera from dye-exposed workers who have IgE antibodies to Procion Orange MX2R, an azo dye containing the dichlorotriazine group. As a control group we have used dye-exposed workers with IgE antibody to Remazol Black B, a diazo dye containing the vinyl sulfone-reactive group. RESULTS: Using RAST and RAST inhibitions, we identified negligible cross-reactivity between CyCl and dichlorotriazine dye. CONCLUSION: The results of this study imply that the allergenic moiety on the dye residue resides in the chromophore rather than in the common structural component of CyCl and dichlorotriazine dyes.

Antibody Specificity↗
PubMed1998

Dementia and ethnicity.

Ethnic differences in rates of dementia nationally, within multiethnic communities, and internationally have important repercussions. The question "Do ethnic differences exist in rates of dementia?" is a crucial one that has implications for service delivery and also offers opportunities for future research on possible etiological factors. Epidemiological surveys suggest that ethnic and geographical differences do occur in rates of dementia, but cross-cultural surveys are fraught with problems. The need for further methodologically sound, cross-cultural comparative studies is paramount to confirm or disclaim the ethnic differences observed to date.

Africa↗
PubMed1998

Cutaneous vascular infarcts secondary to spontaneous platelet aggregation.

We report a 23-year-old woman presenting with multiple cutaneous infarcts who was found to have spontaneous platelet aggregation (SPA). Her skin lesions showed a good response to aspirin therapy and platelet aggregation returned to normal. Subsequently, she was found to have and was treated for pulmonary tuberculosis. The SPA may have been related to this via the formation of immune complexes. Isolated cutaneous infarcts have not previously been described in association with SPA. The role of spontaneous and increased platelet aggregation in skin disorders is discussed.

Adult↗