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Biomedical subjects

S Patterson

Publications and source records attributed to S Patterson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Evoked potential monitoring during posterior fossa aneurysm surgery: a comparison of two modalities.

The purpose of this study was to compare and assess the ability of two different evoked potential (EP) modalities, median nerve somatosensory evoked potentials (SSEP) and brainstem auditory evoked potentials (BAEP) in monitoring for cerebral ischaemia and in predicting neurological outcome during posterior fossa aneurysm surgery. During 70 procedures, patients were monitored with both SSEP and BAEP. Temporary occlusion of an artery was used in 52 patients and permanent occlusion in 21 patients. A change was defined as a greater than 50% decrease in amplitude and/or an increase in latency greater than 1 msec of the N20 (cortical waveform) for SSEP monitoring and of the fifth peak for BAEP monitoring. Neurological assessment of the patient was performed immediately on emergence, after 24 hr and at the time of discharge. In total, 14 patients had an SSEP change which predicted a neurological deficit in eight patients (57%). Ten patients had a change in BAEP; six had a neurological deficit (60%). Five patients had a change in both, two had a deficit (40%). The incidence of false negative results (a neurological deficit but no EP change) for both modalities was 20% (SSEP 47%, BAEP 60%). The incidence of false positive results (an EP change but no deficit) was 13% overall (SSEP 11%, BAEP 7%). All patients who had a permanent EP change developed a neurological deficit. We did not find a difference in the ability of SSEP compared with BAEP in predicting neurological deficits but, using both modalities, the incidence of false negative results was decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Reliability of measurements of static weight distribution of manual wheelchairs.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the reliability of measurements of weight distribution among the wheels of wheelchairs using a commercial balance testing system. Reliable data may be useful in the wheelchair evaluation and adjustment process. SUBJECTS: Three male full-time manual wheelchair users aged 30, 26, and 27 years with cervical spinal cord injuries 7.5, 6.5, and 10 years in duration participated. METHODS: Calibration weights, unoccupied wheelchairs, and occupied wheelchairs were repeatedly placed on the force transducers of the balance testing system to obtain measurements of weight distribution. RESULTS: The intraclass correlation coefficients of the measurements were .99 for calibration weights, .96 for unoccupied wheelchairs and .98 for wheelchairs occupied by the subjects. CONCLUSION AND DISCUSSION: The described use of this instrumentation appears to generate reliable measurements of static weight distribution. With further testing, this system may provide useful information related to manual wheelchair prescription and adjustment.

Adult↗
PubMed1994

Is use of hospital services a proxy for morbidity? A small area comparison of the prevalence of arthritis, depression, dyspepsia, obesity, and respiratory disease with inpatient admission rates for these disorders in England.

OBJECTIVES: To examine the relationship between specific types of morbidity, measured by validated survey questions, and hospital service use and mortality to see if the latter two could act as a proxy in health needs assessment, health service planning, and resource allocation in a typical health district. DESIGN: A postal questionnaire was used to provide information about depression, digestive disorders, musculo-skeletal disorders, obesity, respiratory disease, and hip and knee pain. The questions were from survey instruments that have been widely used to derive information about these conditions. The relationships between the prevalence of these specific types of morbidity and appropriate admission and mortality rates were explored using linear regression and Pearson correlation analysis. SETTING: The population of Rotherham health district, England. SUBJECTS: A simple random sample of the residents of each of the 22 electoral wards in Rotherham health district. RESULTS: Responses were obtained from 78% of the 5000 sampled (82% after excluding people who had moved house or died). Significant, positive correlations were found between the prevalence of respiratory disease and the hospital admission and mortality rates for respiratory problems (r = 0.68, p < 0.01 and r = 0.54, p < 0.01) and the prevalence of depression and the admission rate for depression (r = 0.52, p < 0.05). No such relations were found for digestive disease, musculo-skeletal disease, and obesity. For the conditions examined here, hospital service use was a more useful measure than mortality. CONCLUSIONS: Only two diseases (respiratory disease and depression) out of the seven diseases or procedures investigated showed a positive correlation between hospital admission and disease prevalence. But even for these two, the correlations explained less than 50% of the variance. Caution must be exercised when hospital service use is being considered as a proxy for morbidity.

Adolescent↗
PubMed1994

Blunted natriuretic response to a high-sodium meal in obese dogs. Role of renal nerves.

Although the relation between body weight and arterial pressure is well established, the mechanisms involved in the pathogenesis of obesity-related hypertension are unclear. However, recent studies suggest that abnormalities in renal function may be involved. The purpose of this study was to test the hypothesis that obese animals have a reduced ability to excrete a sodium load as a result of abnormal renal nerve function. To quantify the role of renal nerves, we examined changes in renal hemodynamics and sodium excretion in response to a high-sodium meal (200 mmol Na) in separate innervated and denervated kidneys simultaneously within the same conscious dog. Two surgically designed hemibladders with indwelling catheters were used to collect urine from innervated and denervated kidneys of the same dog. Body weight averaged 19.9 +/- 1.0 kg in the control lean dogs and 25.1 +/- 1.1 kg in the obese dogs. Arterial pressure averaged 101 +/- 4 mm Hg in the obese dogs and 90 +/- 4 mm Hg in the lean dogs. In response to the high-sodium meal in lean dogs, urinary sodium excretion increased from 20.8 +/- 4.2 to 189.7 +/- 21.2 mumol/min in the innervated kidneys and from 25.3 +/- 5.9 to 194.8 +/- 26.9 mumol/min in the denervated kidneys. In contrast, urinary sodium excretion in obese dogs increased from 9.6 +/- 1.4 to 129.9 +/- 34.3 mumol/min in the innervated kidneys and from 18.4 +/- 3.7 to 125.2 +/- 30.5 mumol/min in the denervated kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Dynamic external fixation of unstable fractures of the distal part of the radius. A prospective, randomized comparison with static external fixation.

A prospective, randomized study was done to compare the results of dynamic external fixation (the Clyburn device) with those of static external fixation (the AO/ASIF device) in the treatment of fifty unstable fractures of the distal part of the radius. Mobilization of the wrist from neutral to 30 degrees of flexion was begun in the dynamic-fixator group at approximately two weeks, and full motion, allowing 30 degrees of extension, was started at approximately four weeks. The external fixation frames in both groups were kept in place for approximately ten weeks. Mobilization of the wrist in the dynamic-fixator group provided little gain in the mean motion of the wrist at the time of the removal of the fixator or at the one, six, or twelve-month evaluation. The static-fixator group had greater flexion of the wrist and radial deviation at the early and late follow-up examinations, while the dynamic-fixator group demonstrated only greater ulnar deviation one month after the fixator had been removed. Motion of the wrist in the dynamic-fixator group resulted in a statistically significant loss of radial length compared with that in the static-fixator group (four millimeters compared with one millimeter, p < 0.001). Complications were more frequent in the dynamic-fixator group. As evaluated with a modification of the scoring system of Gartland and Werley, 92 percent of the results at one year were excellent or good in the static-fixator group and 76 percent, in the dynamic-fixator group. The results of this study cannot support the concept of early mobilization with a dynamic external fixator for the treatment of unstable fractures of the distal part of the radius.

Adult↗
PubMed1994

Increased erythrocyte sedimentation rate and a splenic mass.

This discussion was selected from the weekly Grand Rounds in the Department of Medicine, University of Washington School of Medicine, Seattle. Taken from a transcription, it has been edited by Jonathan G. Drachman, MD, Chief Medical Resident; Henry Rosen, MD, Professor and Associate Chair; and Paul G. Ramsey, MD, Professor and Chair of the Department of Medicine.

Adult↗
PubMed1994

Retrovirus-induced immunosuppression via blocking of dendritic cell migration and down-regulation of adhesion molecules.

Dendritic cells (DC) within tissues may acquire and process antigens, carry them into lymph nodes and cluster and activate T cells. The ability of DC to acquire antigen and to migrate to lymph nodes was estimated during murine retroviral infection caused by Rauscher leukaemia virus (RLV). A novel mechanism of inducing immunodeficiency has now been identified. In mice infected with RLV, DC failed to migrate into lymph nodes following exposure of the skin to the contact sensitizer, fluorescein isothiocyanate. RLV infection of a proportion of DC both in skin and lymph nodes, shown by semi-quantitative polymerase chain reaction (PCR) and down-regulation of expression of adhesion molecules (CD54 and CD44) on the surface of Langerhans' cells, may contribute to the described phenomenon. A failure of DC migration could be an important immunosuppressive mechanism of RLV infection in mice and we speculate on a similar role for DC in human immunodeficiency virus-1 (HIV-1) infection in humans.

Animals↗
PubMed1993

Dendritic cells in HIV-1 and HTLV-1 infection.

Individuals with HIV-1 infection show two major immunological effects--the early persistent stimulation of immune responses (e.g. of CD8 cells and antibody production) and later catastrophic immunodeficiency. Peripheral blood dendritic cells (DC) become infected with HIV-1 and infected cells can stimulate responses to virus. By contrast infected DC show a reduced capacity to stimulate either primary or secondary responses to other antigens. We have proposed that the block, particularly in primary responses, may be instrumental in the development of immunodeficiency. In HTLV-1 infected patients with tropical spastic paraparesis (TSP) a major feature of disease is 'spontaneous' T cell proliferation thought to underlie development of inflammatory neurological disease. We have now shown that some DC in addition to T cells are infected in TSP and that DC stimulate the persistent T cell activity. Here we demonstrate this using cells from an informative family where the daughter was normal, the father an HTLV-1 seronegative carrier and the mother had TSP. DC from all individuals stimulated normal allogeneic T cells in a mixed leukocyte reaction (MLR) and T cells responded well to normal allogeneic DC. T cells from the daughter showed little stimulation with autologous DC, those from the father showed significant but low stimulation, and T cells from the TSP patient gave a response to autologous DC which exceeded that to allogeneic DC. Taken together, the studies of DC and both HIV-1 and HTLV-1 indicate that infection of DC may play a central role in development of T cell abnormalities in human retrovirus-induced diseases.

Carrier State↗
PubMed1993

Are deprivation indicators a proxy for morbidity? A comparison of the prevalence of arthritis, depression, dyspepsia, obesity and respiratory symptoms with unemployment rates and Jarman scores.

The aim of the study was to examine the relationship between specific areas of morbidity measured using validated survey questions and deprivation indicators to see if the latter could act as a proxy in health needs assessment, health service planning and resource allocation in a typical health authority. A postal questionnaire was used to provide information about arthritis, depression, dyspepsia, obesity and respiratory symptoms in a simple random sample from the study population. The questions were from survey instruments that have been widely used to derive information about these conditions. The relationships between the prevalence of these specific areas of morbidity and both unemployment and the Jarman Underprivileged Areas Score were explored. Spearman's rank correlation coefficients were calculated and compared for each combination of measures. The study population was a random sample of the residents of each of the 22 electoral wards in Rotherham Health Authority. Responses were obtained from 82 per cent of the 5000 sampled. Although all morbidity measures showed positive correlations with both Jarman score and unemployment, some, notably those relating to respiratory disease and depression, were much more strongly correlated than others, such as obesity. There was no difference between unemployment and Jarman score in respect of the magnitude of the correlation coefficients. In conclusion, for some, but not all, conditions socio-economic measures are a good proxy for morbidity. Unemployment is just as useful a proxy as the Jarman score.

Arthritis↗
PubMed1993

Dendritic cells infected in vitro with human T cell leukaemia/lymphoma virus type-1 (HTLV-1); enhanced lymphocytic proliferation and tropical spastic paraparesis.

Evidence supporting a role of the dendritic cell (DC) in stimulating autologous T cell activity in tropical spastic paraparesis (TSP) was sought by studies of cells taken from healthy volunteers and exposed to HTLV-1 in vitro. DC were co-cultured with an HTLV-1-producing cell line (MT-2) at 1:1 or 10:1 ratios. These DC stimulated high levels of proliferation in autologous T cells. This was similar to that seen in an autologous mixed leucocyte reaction (AMLR) using cells from TSP patients. The requirement for both DC and virus was confirmed, since neither DC co-cultured with uninfected MT-2 cells nor addition of infected MT-2 cells directly to T cells caused significant stimulation. DC exposed to the highest dose of HTLV-1 (1:1) for 24 h before addition of T cells caused strong stimulation that increased after 8 h but almost disappeared by 72 h. In situ hybridization showed that approximately 25% of DC became infected in cultured cells after preincubation for 24 h, and over 50% were infected with a 72-h preincubation. We suggest that infection of DC by HTLV-1 may be an initial step in altering the immune system in seronegative patients, and that persistent T cell stimulation in those with genetic susceptibility may underlie the production of neurological disease.

Aged↗
PubMed1993

Sometimes Jello helps: perceptions of headache etiology, triggers and treatment in literature.

Throughout history writers have attempted to describe the symptoms and evoke the misery of "a dismal headache." Writers from Plato to Stephen King have used the phenomenology of headache to illustrate their work. Lewis Carroll, for example, vividly describes the central scotoma, tunnel vision, phono-phobia, vertigo, distortions in body image, dementia and visual hallucinations that often accompany migraine. Although many authors have discussed the topic seriously, others have addressed the issue in a dismissive and even contemptuous manner, relegating this very real disorder to the status of a medical stepchild. We will examine headache etiology, triggers and treatment and explore the attitudes toward headache and headache sufferers found in literature. We have recently seen a growing understanding of the physiological basis of headaches. However, this knowledge has not yet reached the level of literature or popular culture. In an age when it seems every Sunday night brings a new "disease of the week" movie, and every human ill is subjected to often intense and numbing scrutiny by the media, the anguish of a chronic migraine sufferer will probably remain unexplored--unless she kills her husband and children during an attack.

Headache↗
PubMed1992

Medium technology in health care.

The health care industry relies on technological innovation to provide solutions to the ever increasing range of medical problems in the modern world. No industry can survive without financial investment, and some areas of the health care industry have encountered difficulties when trying to attract finance. In this article, the author outlines specific areas that are likely to attract investment funding and the elements that make up an attractive proposition for potential investors.

Capital Financing↗
PubMed1992

Antigen-presentation by macrophages but not by dendritic cells in human immunodeficiency virus (HIV) infection.

Dendritic cells (DC) have a potent antigen-presenting capacity for recruiting resting T cells into immune responses. They also promote expansion of already activated memory T cells. By contrast, macrophages (M phi) are only effective in stimulating memory responses. Infection and depletion of DC occur in human immunodeficiency virus (HIV)-infected individuals and recruitment of T cells into primary responses is blocked. Here comparisons between DC and M phi in stimulating secondary T-cell responses in HIV infection were made. Adherent M phi, and DC isolated by a new method, were separated from peripheral blood of patients in different stages of HIV infection and from uninfected controls and added to allogeneic lymphocytes in mixed leucocyte reactions (MLR). Some were pulsed with influenza virus or tetanus toxoid and used to stimulate autologous T cells. Responses were measured from uptake of [3H]thymidine in 20 microliters hanging drop cultures. DC, but not M phi, from normal individuals stimulated MLR but both populations stimulated secondary responses to recall antigens. DC from all HIV seropositive individuals caused little or no stimulation of any lymphocyte responses. However, M phi from HIV seropositive asymptomatic individuals and those with persistent generalized lymphadenopathy stimulated responses to recall antigens. There was no stimulation using cells from acquired immune deficiency syndrome (AIDS) patients. Blocked DC but not M phi function may underlie progressive immunological non-responsiveness in HIV infection. Without recruitment of resting T cells, loss of memory T cells may be cumulative; failure of secondary activation (e.g. by M phi) would lead to lost T-cell activity. Identification and circumvention of the defect in DC could offer new therapeutic approaches.

Antigen-Presenting Cells↗
PubMed1991

Stimulatory and suppressive effects of infection of dendritic cells with HIV-1.

Two effects of HIV infection on human dendritic cells (DC) in vitro have been examined. The first was the stimulation of primary responses to HIV antigens in autologous lymphocytes from normal donors. When DC were exposed to HIV (10(4) TCID/10(5) cells) for up to 24 h before addition to autologous lymphocytes, a marked primary proliferative response to the virus was observed. No proliferative response was seen when the period of pre-exposure of DC to virus was extended. Cytotoxic T cells specific for HIV-infected target cells developed in stimulated cultures. The second effect of HIV infection of DC was to block responses to other antigens, such as alloantigens and the recall antigens tetanus toxoid and influenza virus. This inhibitory effect was only evident when the DC were exposed to HIV for longer than 24 h before being added to cultures. These in vitro studies suggest that infection of DC can produce both stimulatory and inhibitory responses in lymphocytes. Such effects operating through DC might underlie in vivo activity of HIV both in stimulating the proliferation of lymphocytes (e.g., in persistent generalised lymphadenopathy) and in the development of immunosuppression.

Dendritic Cells↗
PubMed1991

A tape-recorded test of hypnotic susceptibility for screening headache patients: a feasibility study of the Harvard Group Scale of Hypnotic Susceptibility, Form A.

A study to examine the feasibility of using the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS) as a screening instrument was undertaken at an inpatient headache treatment program. Nine patients diagnosed with chronic daily headache and drug rebound were administered the HGSHS. Analysis of the results showed no significant difference in hypnotic susceptibility when headache patients were compared to a control group. After taking the HGSHS, three of the five subjects who had headache at the time of testing reported a 25% reduction in pain, one was unchanged, and one reported a 13% increase in pain. The results obtained did not suggest a correlation between level of hypnotic susceptibility and reduction of headache.

Adult↗