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Biomedical subjects

M J Harrison

Publications and source records attributed to M J Harrison.

At least 91 records · Page 5Linked to original sources
PubMed1997

Prediction of infusion rates of rocuronium using the bolus test dose technique.

Twenty-four patients were given a loading dose of rocuronium 1.0 mg.kg-1 intravenously followed by boluses of 20 mg (n = 19) and 10 mg (n = 24) after return of T1 of the train-of-four to 5% of control. Neuromuscular function was assessed using a Relaxograph. The time was recorded for the return of T1 to 5% after the administration of the boluses and subsequently an infusion of rocuronium was started. The aim was to maintain T1 between 3% and 7% of control for at least 40 min without a change of infusion rate. The correlations between the duration of the test doses and the infusion rates were -0.94 (10 mg) and -0.86 (20 mg). The predictive accuracy of the 10 mg bolus was assessed in a further 10 patients. At the termination of the infusion three patients had a T1% that was outside the desired range of 3-7%. A 10 mg bolus that lasts 6 min indicates a need for an infusion of at least 60 mg.h-1, 8 min (50 mg.h-1), 10 min (40 mg.h-1), 15 min (30 mg.h-1), 24 min (20 mg.h-1) and 34 min (15 mg.h-1).

Adolescent↗
PubMed1997

A preliminary evaluation of ankle orthoses in the management of children with cerebral palsy.

The effectiveness of ankle-foot orthoses (AFOs) on walking pattern was studied in 12 children with cerebral palsy between the ages of 3 and 7 years. Over a 2-year period two trials of fortnightly periods without AFOs were carried out. The range of ankle dorsiflexion, video analysis looking specifically at footfall, and rank scoring of the mediolateral shear force obtained using an oscilloscope printout from a Kistler force platform were compared with measurements obtained during periods when the child was wearing AFOs. The results using different outcomes were consistent, and indicated that the range of movement and gait deteriorated during the two trial periods during which the splints were not worn compared with periods during which the splints were worn. This finding needs to be confirmed in a large randomised controlled trial.

Ankle↗
PubMed1997

Social networks of women caregivers.

Social networks and the support that network members provide are important resources for family caregivers in sustaining their caregiving role. Caregivers' perceptions of support from family and friends have been linked to their health status (R. Kahn & T. Antonucci, 1980; I. Sandler & M. Barrera, 1984). The purpose of this study was to explore the social networks and types of perceived support described by women who are caregivers of cognitively impaired older adults. Content analysis was used to examine interview data from a longitudinal qualitative study of 20 women caregivers of cognitively impaired older persons. An important finding of this study was the identification of a typology of social networks of the women caregivers. The caregivers' perceptions of satisfaction with support received and experience of conflict with network members varied according to the characteristics of their social network. Those caregivers who belonged to diverse social networks reported high satisfaction with the support that they received and little or no conflict. Those caregivers with kin-dominated social networks reported little satisfaction with support received and a high degree of conflict.

Adult↗
PubMed1997

Correlation of MRI and neuropathology in AIDS.

OBJECTIVE: To assess the correlation between findings on radiological and neuropathological examinations of the brain. METHODS: The formalin fixed brains of 19 patients who had died of AIDS were examined by MRI and neuropathology. RESULTS: The rate of identification of cerebral atrophy was similar radiologically and neuropathologically. However, only in half of these cases were the two examinations concordant in the diagnosis. Furthermore, in the 15 brains which had radiological diffuse white matter lesions, the underlying pathology was heterogeneous. CONCLUSIONS: The possible reasons for the inconsistencies, and their relevance to the interpretation of imaging studies, are discussed. The study suggests that the qualitative identification of atrophy in the postmortem brain is problematical and that diffuse white matter lesions seen on MRI are not indicative of a specific pathological process.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Comparison of magnetic resonance imaging with neuropathological findings in the diagnosis of HIV and CMV associated CNS disease in AIDS.

OBJECTIVES: To compare the results of clinical assessment and MRI with neuropathological findings in the diagnosis of HIV and cytomegalovirus (CMV) associated CNS disease. METHODS: A retrospective study of 35 patients infected with HIV who were examined at necropsy between four and 70 (median 20) days after neurological assessment and MRI. RESULTS: Of the 35 patients, 19 had diffuse white matter hyperintensity on T2 weighted MRI, six of whom also had focal lesions. Nine other patients had focal white matter lesions and seven had changes in cortical atrophy only. Necropsy in the 19 with diffuse white matter hyperintensity showed HIV leukoencephalopathy (HIVLEP) with encephalitis in 10, CMV encephalitis in three, both HIVLEP/HIV encephalitis and CMV encephalitis in one, lymphoma in three, and non-specific inflammation in two. Necropsy in the 16 other patients without diffuse white matter hyperintensity showed CMV encephalitis in six, HIV encephalitis (without HIVLEP) in two, CMV encephalitis and HIVLEP/HIV encephalitis in one, non-HIV associated abnormalities in five, herpes simplex encephalitis in one, and lymphoma in one. CMV DNA was detected in CSF of five of seven patients with CMV encephalitis and in two of two with CMV associated polyradiculopathy but without CMV encephalitis. Diffuse white matter hyperintensity on MRI had a sensitivity of 100%, a specificity of 66.6%, and a positive predictive value of 58% for diagnosis of HIVLEP. CONCLUSION: Diffuse white matter hyperintensity on MRI can be due to either HIV or CMV associated pathology or non-specific abnormalities.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Proton MRS and quantitative MRI assessment of the short term neurological response to antiretroviral therapy in AIDS.

OBJECTIVE: To investigate MRI and proton spectroscopy changes in five patients with HIV associated dementia complex (HADC) treated with antiretroviral therapy. METHODS: Three markers were evaluated: (1) CSF/intracranial volume ratio; (2) T2 weighted signal ratio between parieto-occipital white and subcortical grey matter; and (3) metabolite ratios from long echo time (TE=135 ms) single voxel proton spectra of parieto-occipital white matter. RESULTS: Spectroscopic changes indicated initial increases in N-acetyl/(N-acetyl + choline + creatine) ratio (NA/(NA+ Cho+Cr)) and progression of atrophy after initiation of antiretroviral therapy in four of five patients. When the neurological status of the patients subsequently deteriorated (two of five patients), the NA/(NA+Cho+Cr) ratio also declined. CONCLUSIONS: Spectroscopic changes mirror reversible neuronal dysfunction. These objective, non-invasive techniques may be used for monitoring the neurological effects of antiretroviral drug therapy in patients with HADC.

AIDS Dementia Complex↗
PubMed1997

Cerebrospinal fluid ferritin in HIV infected patients with acute neurological episodes.

OBJECTIVES: To measure cerebrospinal fluid (CSF) ferritin in HIV infected patients with acute neurological episodes and to correlate the findings with the type and severity of neurological disease. METHODS: CSF ferritin and the ratio of CSF to serum albumin (QAlb) were prospectively measured in 27 consecutive HIV infected patients admitted to a specialist unit for investigation of acute neurological episodes; the results were compared with their clinical diagnoses. RESULTS: Ten patients had HIV associated dementia complex, six had cryptococcal meningitis, two had primary CNS lymphoma and nine had miscellaneous conditions including herpes simplex virus encephalitis, cytomegalovirus encephalitis, cerebral toxoplasmosis and mononeuritis multiplex. Overall, 16 (59%) patients had raised CSF ferritin levels, ranging from 13.0 to 50.2 micrograms/l, (median = 16.1 micrograms/l: normal range = 1.0-12.0 micrograms/l). Thirteen of the 16 also had normal QAlb values, implying an intact CSF-blood barrier, and thus that local synthesis of ferritin had occurred. Elevated ferritin levels were not associated with particular neurological diagnoses. In those with HIV associated dementia complex there was no correlation between CSF ferritin levels and the severity of clinical cognitive deficit or the extent of magnetic resonance imaging abnormalities. CONCLUSIONS: An elevated CSF ferritin level is a non-specific finding in HIV infected patients presenting with acute neurological episodes.

AIDS Dementia Complex↗
PubMed1997

Past childhood experiences and current parent-infant interactions.

To examine the relationships between adults' childhood experiences in their family of origin, current level of marital support, and quality of parenting interactions, 66 mothers and fathers were observed individually interacting with their infants during home visits using a standardized observational measure (Nursing Child Assessment Teaching Scale). Parents completed questionnaires on marital support (Dyadic Adjustment Scale) and on childhood experiences in the family of origin (Parental Acceptance-Rejection Questionnaire). For mothers, there was no relationship between childhood experiences and the quality of parenting interactions. For fathers, the relationship varied as a function of marital support. Fathers who perceived less positive childhood experiences but who had more optimal levels of marital support were predicted to have more responsive parenting interactions.

Adult↗
PubMed1997

Proton Spectroscopy in a Cross-Section of HIV-Positive Asymptomatic Patients Receiving Immediate Compared with Deferred Zidovudine (Concorde Study).

The purpose of this study was to examine by proton spectroscopy for any difference in cerebral metabolites in patients taking part in the Concorde study (comparing the efficacy of immediate versus deferred treatment with zidovudine on asymptomatic HIV infected individuals). Forty seven HIV positive male patients [29 immediate, 18 deferred zidovudine] were examined in the last 9 months of the therapeutic trial. Magnetic resonance imaging and proton spectroscopy were performed at 1.5 Tesla using a single voxel placed in the parieto-occipital white matter. No significant difference was found in metabolite ratios comparing immediate versus deferred zidovudine (NA/NA+Cho+Cr 0.52 vs. 0.52). High quality spectra were acquired in relatively large numbers of patients and logistically spectroscopy may be applied to clinical therapeutic studies.

HIV Infections↗
PubMed1997

Effects of combined glutamate and platelet-activating factor inhibition on the outcome of focal cerebral ischaemia - an initial screening study.

Since both glutamate excitotoxicity and inflammatory responses have been implicated in ischaemic neuronal death, we questioned whether joint inhibition of both processes would be more neuroprotective than either on its own. Therefore we assessed the effects of combined inhibition of both glutamate release (with a use-dependant sodium channel blocker, 619C89) and inflammatory processes (with a platelet-activating factor (PAF) receptor antagonist, BB-823) on the degree of motor deficit and the extent of cerebral (cortical and sub-cortical grey matter) infarction produced by middle cerebral artery occlusion (MCAO) in the rat, and compared results to appropriate single agent, vehicle and positive controls. The combination of both agents produced the greatest reduction in motor deficit, but the effect was only significant (p<0.05) acutely (4 to 6 hours post-MCAO). The extent of cortical infarction at 24 hours post-MCAO was significantly reduced in all experimental groups compared to vehicle-controls (p<0.05) and the greatest reduction occurred in the combination group (55%), though it was not significantly better than either of the single agent groups. Similarly the greatest reduction in sub-cortical infarction was in the combination group, but this was also not significantly better than the single agents. The results of this novel combination of pharmacological interventions suggest that inhibition of both glutamate excitotoxicity and inflammatory responses afforded an overall enhanced, if modest, neuroprotective effect, compared to inhibition of either process alone. The possible mechanisms involved are discussed, but warrant further clarification before therapeutic strategies are developed.

Animals↗
PubMed1996

A multicenter proton magnetic resonance spectroscopy study of neurological complications of AIDS.

Human immunodeficiency virus (HIV) infection as seen in Europe and the United States has predominantly been contracted through male homosexual sex or intravenous drug abuse. In infected subjects, the brain is frequently affected both clinically and neuropathologically. The aim of this multicenter study has been to evaluate the value of single-voxel proton magnetic resonance spectroscopy (MRS) in the assessment of the neurological complications of acquired immunodeficiency syndrome (AIDS). MRS (voxel size = 8 ml, TR/TE = 1600/135 msec) was performed in 137 HIV-1-seropositive patients and 64 healthy controls without risk factors at three clinical MR sites operating at 1.5 T. The first result of this multicenter trial is that good reproducibility of results among participating sites was found. This demonstrates the reliability and robustness of MRS in the study of in vivo brain metabolism. In HIV patients, there was no significant correlation between metabolite ratios of brain detected by MRS and CDC grouping of patients or CD4 count. In contrast, the variations of brain metabolite ratios (NA/Cr, NA/Cho, and Cho/Cr) were related to the occurrence of encephalopathy, brain atrophy, or diffuse white matter lesions. There was no significant difference in brain metabolites between male homosexual AIDS patients and male intravenous drug user AIDS patients, whatever their neurological status (neurosymptomatic or neuroasymptomatic). Thus, the mode of transmission of HIV infection does not appear to affect the cerebral changes observed in the proton spectra from AIDS patients. Because of its ease of implementation and high information content, single-voxel proton MRS is likely to play a significant role in the evaluation of HIV-related encephalopathies.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Mother and father interactions over the first year with term and preterm infants.

Mothers and fathers of 54 term infants and 49 preterm infants were observed individually interacting with their infant in the home during a structured task (Nursing Child Assessment Teaching Scale) when the child was 3 and 12 months old. Parents of preterm infants had lower interaction scores than parents of term infants. Differences between the groups were not explained by differences in the behavior of the infant, in levels of stress (measured by the Parenting Stress Index), in marital support (measured by the Dyadic Adjustment Scale), or in level of involvement with their child. Fathers of both term and preterm infants had lower interaction scores than mothers. Parents' interaction scores decreased over time, while the responsiveness and clarity of cues of the infants increased over time. The results are discussed in relationship to other research on prematurity stereotyping and the vulnerable child syndrome.

Adult↗
PubMed1996

Cerebral magnetic resonance relaxometry in HIV infection.

A prospective, cross-sectional study was designed to determine the magnetic resonance relaxation times of cerebral white matter in human immunodeficiency virus (HIV) infected individuals. T1 and T2 were estimated at 1.5 T using four-point methods. Seventy-five HIV-1 seropositive subjects, 48 seronegative blood donors, and 17 seronegative homosexual men were studied. Associations between relaxometry and clinical classification, neurological status, immunological status, and qualitative MRI were investigated. Statistically significant differences in white matter T1 relaxation time were found comparing low-risk control and AIDS groups (p < .005), seropositive subjects with neurological signs and those without (p < .005), and subjects with low (CD4 < or = 200 x 10(6)/l) and high (CD4 > 200 x 10(6)/1) CD4 cell counts (p < .05). These findings add to the body of information that reveals no HIV-related change in the brain before the onset of symptomatic immunosuppression and go someway to validating the previous visually rated, qualitative findings. Statistically significant difference in white matter T2 relaxation time were also found comparing the two control groups (p < .005) highlighting the need for appropriate controls.

AIDS Dementia Complex↗
PubMed1996

The spectrum of MRI findings in CNS cryptococcosis in AIDS.

We retrospectively reviewed the cranial MRI appearances of 25 patients with AIDS and microbiologically proven central nervous system (CNS) cryptococcosis. Four patients had a normal scan. Ten patients had dilated perivascular Virchow-Robin spaces that were hyperintense on T2-weighted images. Nine of these patients developed progressive cryptococcomas, eight in the basal ganglia and one in the cerebral white matter. The cryptococcomas displayed high signal on T2-weighted and intermediate to low signal on T1-weighted images. None enhanced after dimeglumine gadopentetate. No abnormal dural or leptomeningeal enhancement was detected in any patient. One patient developed an acquired arachnoid cyst during treatment of CNS cryptococcosis which was thought to represent a focal collection of organisms and mucoid material within the subarachnoid space. In addition either cerebral atrophy and/or background white matter hyperintensity on T2-weighted images was present in 19/25 patients. In two patients the neuropathological findings at autopsy correlated well with the imaging abnormalities. In conclusion, this spectrum of MRI appearances in CNS cryptococcosis reflects the pathological mechanism of invasion by the fungus, but a normal scan or one with features of CNS HIV infection such as atrophy or white matter hyperintensity does not exclude the diagnosis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Sub-cortical white-grey matter contrast on MRI as a quantitative marker of diffuse HIV-related parenchymal abnormality.

White matter change occurs in human immunodeficiency virus (HIV) encephalopathy, which may be difficult to assess subjectively especially in the early stages of disease. This study applies a quantitative approach to the assessment of this finding. Sixty-three HIV seropositive subjects, 47 seronegative blood donors and 17 seronegative homosexual men underwent axial T2 weighted MRI of the brain at 1.5T. Quantitative analysis was performed by obtaining the pixel contrast between parieto-occipital white matter and head of caudate grey matter (Cwg). Highest values of Cwg were found in a subgroup of subjects with AIDS who had diffuse/patchy white matter abnormalities and atrophy on qualitative image assessment. Statistically significant differences were found in Cwg between subjects with high (> or = 200 x 10(6)/I) and low (< 200 x 10(6)/I) CD4 lymphocyte counts (P < 0.05) and between subjects with and without HIV-1 associated cognitive/motor complex (P < 0.05). This technique provides an objective measure of diffuse HIV-related parenchymal abnormality seen on T2 weighted MRI.

AIDS Dementia Complex↗
PubMed1996

Focal cerebral ischaemia increases the levels of several classes of heat shock proteins and their corresponding mRNAs.

The induction of focal cerebral ischaemia in rats by middle cerebral artery occlusion has previously been shown to increase, over time, the mRNA levels of the heat shock proteins (HSPs) 27 and 70. However, the levels of HSP90 mRNA remain constant. In contrast, during global ischaemia, HSP70 and HSP90 mRNA levels are both raised, particularly in the CA1 neurons in the hippocampus, an area that is resistant to the insult in comparison to the surrounding regions. HSP27 mRNA is raised in the neuroglia in the subregions of the hippocampus. However, the protein levels of HSP27, 70 and 90 have not been characterised in focal ischaemia. With this data in mind, we have carried out a comparative study of HSP27, 56, 60, 70 and 90 mRNA and protein levels during focal cerebral ischaemia in rats, up to 24 h post-occlusion. We have shown that HSP70 and HSP27 mRNA levels are increased and also that HSP60 mRNA levels (which had also not previously been characterised in this model of focal ischaemia) are significantly raised. HSP90 and HSP56 mRNAs were not significantly elevated. On Western blot analysis, the inducible HSP72 protein was first detected at 8 h post-occlusion, HSP27 protein was detected only at 24 h post-occlusion and HSP60 protein, although constitutive, appeared to increase at 24 h post-occlusion. HSP56 protein levels appeared to rise on the occluded side, but HSP90 protein levels remained constant.

Animals↗
PubMed1996

Educational issues in preparing community health nurses to use nursing diagnosis with population groups.

Recently there has been increased interest in the use of nursing diagnosis by community health nurses who work with population groups in community settings. The purpose of this article is to discuss educational issues important in the preparation of undergraduate students and practising community health nurses in the use of nursing diagnosis with population groups. The educational issues discussed emerged from the findings of a preliminary survey of undergraduate students and community health nurses and were related to: differences in the learning requirements of novice and expert practitioners; common errors in the use of nursing diagnosis; and the perceived benefits and barriers in using nursing diagnosis. There is a need to develop an educational strategy to address these concerns for both undergraduate students and community health nurses.

Clinical Competence↗