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Biomedical subjects

M Alexander

Publications and source records attributed to M Alexander.

At least 55 records · Page 3Linked to original sources
PubMed2000

Accumulation of phenanthrene and pyrene in rhizosphere soil.

A study was conducted to determine PAH concentrations in the rhizosphere of plants grown in soil containing phenanthrene or pyrene. The rhizosphere of tall fescue and wheat grown in sterile soil contained 4-5-fold higher pyrene concentrations than unplanted soil. The rhizosphere of several plant species grown in non-sterile soil temporarily contained appreciably more phenanthrene or pyrene than unplanted soil, but those PAHs were degraded with time. The data suggest that plants accumulate such hydrophobic compounds in the rhizosphere after facilitating their transport toward the roots.

Phenanthrenes↗
PubMed2000

Mdr1 promoter-driven tumor necrosis factor-alpha expression for a chemotherapy-controllable combined in vivo gene therapy and chemotherapy of tumors.

Cancer gene therapy approaches are often designed as single-agent treatments; however, greater therapeutic effect might be obtained if combined with an established conventional treatment regimen such as chemotherapy. In this context, conditional promoters are useful tools, because they may be induced by therapeutic modalities. The human multidrug resistance gene (mdr1) promoter is inducible by cytostatic drugs and can be employed for the chemotherapy-regulated expression of therapeutic genes. In this in vivo study, the human mdr1 promoter fragment (-207 to +158) was used for drug-inducible expression of human tumor necrosis factor-alpha (TNF-alpha) in the vector construct pM3mdr-p-hTNF. The single doxorubicin and vincristine treatment of nude mice xenografted with pM3mdr-p-hTNF-transduced MCF-7 mammary tumors resulted in drug-induced and time-dependent elevation of intratumoral TNF-alpha expression at the mRNA and protein level. The highest drug induction was achieved at 2 days after drug application, as reflected by a maximum 25-fold increase in TNF-alpha secretion in the tumor. This drug-induced TNF-alpha expression is more effective in inhibiting tumor growth compared with the growth of tumors transduced with constitutively TNF-alpha-expressing vectors in combination with chemotherapy.

Antineoplastic Agents↗
PubMed2000

Acute disseminated encephalomyelitis and multiple sclerosis: magnetic resonance imaging differentiation.

The study was undertaken to compare the MR imaging features of acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) in a country with a high prevalence of ADEM. Magnetic resonance scans from 33 patients diagnosed clinically with MS (14 patients) or ADEM (19 patients) were reviewed concurrently by two radiologists blinded to the clinical diagnosis. The size, site, morphology and pattern of brain and spinal cord involvement were recorded and the MR imaging diagnosis was compared with the clinical diagnosis. The MR imaging findings matched with the clinical diagnosis in 11 of 14 patients with MS (sensitivity = 78.6%), and with the clinical diagnosis in 15 of 18 patients with ADEM (sensitivity = 78.9%). Three patients had non-specific findings and in a further three patients discordant imaging features were present. One patient with imaging features typical of Balo's concentric sclerosis was diagnosed clinically as suffering from ADEM. In a country with a high prevalence of ADEM, the majority of patients with ADEM and MS can be differentiated on MR imaging.

Adolescent↗
PubMed2000

Evaluation of guidelines for the use of telemetry in the non-intensive-care setting.

To determine if the American College of Cardiology (ACC) cardiac monitoring guidelines accurately stratify patients according to their risks for developing clinically significant arrhythmias in non-intensive-care settings, we conducted a prospective cohort study of 2,240 consecutive patients admitted to a non-intensive-care telemetry unit over 7 months. Sixty-one percent of patients were assigned to ACC class I (telemetry indicated in most patients), 38% to class II (telemetry indicated in some), and 1% to class III (telemetry not indicated). Arrhythmias were detected in 13.5% of the class I patients, 40.7% of the class II patients, and 12% of the class III patients (p <.001). Telemetry detected an arrhythmia resulting in transfer to an intensive care unit in 0.4% of the class I patients, 1.6% of the class II patients, and none of the class III patients (p =.006). Telemetry led to a change in management for 3.4% of the class I patients, 12.7% of the class II patients, and 4% of the class III patients (p <.001). When patients with chest pain as the reason for admission were moved from class I to class II and patients with arrhythmias as the reason for admission were moved from class II to class I, more arrhythmias and more clinically significant arrhythmias occurred in class I patients and the trends from class I to class III were more consistent with the purpose of the guidelines. These findings indicate that when the ACC guidelines are reexamined, consideration should be given to changing them so they are more useful in non-intensive-care settings.

Arrhythmias, Cardiac↗
PubMed2000

Analysis of arm trajectories of everyday tasks for the development of an upper-limb orthosis.

Spatiotemporal arm and body movements of able-bodied subjects performing nine everyday tasks were recorded for the purpose of guiding the development of an upper-limb orthosis. To provide a user the opportunity to carry out these tasks with natural movements, the orthosis should allow replication of the measured trajectories. We outline the orthosis architecture, which supports the user's upper arm and forearm, and analyze the movement data to obtain orthosis design specifications. Trajectories were obtained using six-degree-of-freedom magnetic position sensors affixed to the wrist, elbow, shoulder, trunk and head. Elbow trajectory data were decomposed into ranges along the principle Cartesian axes to provide a generally useful envelope measure. The smallest Cartesian parallel-piped that contained the elbow trajectories for most tasks was approximately 30 cm front/back, 15 cm side/side, and 17 cm up/down. A rough lower bound estimate obtained by asking subjects to repeat the tasks while minimizing elbow movement substantially reduced movement in the up/down and side/side dimensions. Elbow angles were generally in the range 50 degrees-150 degrees, and the angle of the forearm with respect to vertical was 10 degrees-110 degrees. Raw trajectory data may be downloaded from www://asel.udel.edu/robotics/orthosis/range.h tml.

Activities of Daily Living↗
PubMed1999

Congestive heart failure hospitalizations and survival in California: patterns according to race/ethnicity.

BACKGROUND: Congestive heart failure (CHF) disproportionately affects African Americans, but data are limited concerning CHF hospitalization patterns among Hispanic and Asian populations, the 2 fastest growing ethnic groups in the United States, and race/ethnic patterns of rehospitalization and survival among patients with CHF are unknown. We conducted a study to assess rates of CHF hospitalization, readmission, and survival among diverse populations in California. METHODS AND RESULTS: We used 2 study designs. First, we calculated the population-based incidence of CHF hospitalization in California in 1991. Next we conducted a retrospective cohort study that identified patients initially hospitalized for CHF in 1991 or 1992 and followed these patients for 12 months after their index hospitalization to determine their likelihood of rehospitalization or death. Data were analyzed with Cox proportional hazards models. African Americans had the highest rate of CHF hospitalization. Age-adjusted hospitalization rates were comparable among whites, Latinos, and Asian women and all lower than those in African American, whereas Asian men had the lowest rates. On adjusted analyses, African Americans were more likely than whites and Asians to be rehospitalized (relative risk 1.07; 95% confidence interval 1.04 to 1.10). However, they were less likely to die within the 12-month follow-up period (relative risk 0.86; 95% confidence interval 0.82 to 0.90). Whites, conversely, had the highest posthospitalization mortality rates. CONCLUSIONS: These findings demonstrate important racial-ethnic differences in CHF morbidity and mortality rates. The disparate findings of higher hospitalization and rehospitalization rates and lower mortality rates among African Americans than whites may represent differences in the underlying pathophysiology of CHF in these groups or differences in access to quality care. Further studies are needed to explain these seemingly paradoxical outcomes.

Black or African American↗
PubMed1999

Comparison of topical nedocromil sodium and oral terfenadine for the treatment of seasonal allergic conjunctivitis.

This double-masked, comparative, multicenter study was conducted to assess the onset of action and tolerability of nedocromil sodium 2% ophthalmic solution BID, 60-mg terfenadine tablets BID, and placebo in the treatment of seasonal allergic conjunctivitis. Two hundred sixty-eight patients in whom seasonal allergic conjunctivitis was diagnosed were assigned to 1 of 3 groups and administered study medication for 4 weeks. Patients' mean age was 33 years (range, 12 to 68 years); 57.8% (155 of 268) were female. Demographic characteristics were similar in all 3 groups. Although all 3 groups showed improvement in ocular symptoms, nedocromil sodium was associated with a statistically significantly faster onset of action than was terfenadine or placebo (P = 0.038). During the study, 29 nedocromil sodium-treated patients (36.7%) achieved control of symptoms in < or =2 minutes, and 61 (77.2%) achieved control in < or =15 minutes. The corresponding numbers were 21 (24.7%) and 50 (58.8%) in the terfenadine group and 25 (29.1%) and 48 (55.8%) in the placebo group. The frequency of adverse events was low and similar between groups (nedocromil sodium, 26; terfenadine, 32; placebo, 32). No severe treatment-related adverse events were reported. In conclusion, nedocromil sodium had a significantly faster onset of action than did terfenadine or placebo.

Administration, Oral↗
PubMed1999

Attachment and chemotaxis of melanocytes after ultraviolet irradiation in vitro.

Because ultraviolet (UV) radiation is able to influence the spatial distribution of melanocytes in melanocytic naevi in vivo, we investigated the influence of UV radiation on the ability of melanocytes to adhere to the extracellular matrix proteins fibronectin, laminin and collagen type IV in vitro. In addition, chemotaxis of melanocytes was studied using both fibronectin and the supernatants from irradiated, as well as non-irradiated, keratinocytes and fibroblasts as attractants. Melanocyte attachment to fibronectin was significantly increased 48 h after a single UV irradiation at 30 mJ/cm2 in comparison with that of non-irradiated melanocytes, whereas attachment to laminin and collagen type IV showed only minor changes after UV exposure. The UV-induced increase in attachment to fibronectin was suppressed by preincubation with antibodies against alpha5beta1 or alphavbeta3 integrin. Both immunohistochemistry and flow cytometric analysis showed an increase in alpha5beta1 integrin expression on melanocytes after UV exposure. The chemotaxis of melanocytes to fibronectin was not influenced by UV exposure. A decreasing migration rate of melanocytes towards the supernatants of UVA-irradiated fibroblasts was observed with increasing UVA doses. The chemotactic effects of conditioned medium of keratinocytes towards melanocytes was not influenced either by UVB or by UVA. The results indicate that UV radiation may alter the ability of melanocytes to adhere to certain substrates by modification of integrin expression. Because fibronectin, as the major target protein of UV-altered attachment, is located in the dermis, the UV-induced morphological changes in melanocytic lesions, with an increase in suprabasally located melanocytes within the epidermis, may be due to other changes in the adhesive properties of melanocytes.

Cell Adhesion↗
PubMed1999

Balo's concentric sclerosis: value of magnetic resonance imaging in diagnosis.

We report two cases of Balo's concentric sclerosis that demonstrate the typical magnetic resonance imaging (MRI) findings of concentric rings of demyelination involving the superficial and deep white matter and sparing the cortex. In both cases biopsy was not performed as MRI findings and multi-mode evoked potential studies were consistent with demyelinating illness. The theories regarding the pathogenesis of this peculiar appearance are briefly reviewed.

Adult↗
PubMed1999

Ethnic differences in hormone replacement prescribing patterns.

OBJECTIVE: To determine whether prescription patterns of hormone replacement therapy (HRT) differ in African-American, Asian, Latina, Soviet immigrant, and white women. DESIGN: Retrospective review of computerized medical records. SETTING: The general internal medicine, family medicine, and gynecology practices of an academic medical center. PATIENTS: Women aged 50 years or older with at least one outpatient visit from January 1, 1992, to November 30, 1995. MEASUREMENTS AND MAIN RESULTS: Use of HRT was defined as documentation of systemic estrogen use. The main predictor variable was self-identified ethnicity. Age, diagnosis (coronary heart disease, hypertension, diabetes, osteoporosis, or breast cancer), and median income were included in the analysis. Of the 8,968 women (mean age, 65.4 years) included, 50% were white, 20% Asian, 15% African American, 9% Latina, and 6% Soviet immigrants. Whites (33%) were significantly more likely to be prescribed HRT than Asians (21%), African Americans (25%), Latinas (23%), or Soviet immigrants (6.6%), p < 0.01 for each. Multivariate analysis, comparing ethnic groups and controlling for confounding variables, showed that Asians (odds ratio [OR] 0.56; 95% confidence interval [CI] 0.49, 0.64), African Americans (OR 0.70; 95% CI 0.60, 0.81), Latinas (OR 0.70; 95% CI 0.58, 0.84), and Soviet immigrants (OR 0.14; 95% CI 0.10, 0. 20) were each less likely to be prescribed HRT than were white women. Although women with osteoporosis were more likely to receive HRT (OR 2.28; 95% CI 1.71, 2.99), those with coronary heart disease were not (OR 0.88; 95% CI 0.68, 1.09). CONCLUSIONS: Physicians at this medical center were more likely to prescribe HRT for white women and women with osteoporosis. Further study is needed to address whether these differences in HRT prescribing result in different health outcomes.

Aged↗
PubMed1999

Acquired dural fistulae in benign intracranial hypertension: a short case report.

Venous sinus thrombosis has been regarded as a known cause of intracranial hypertension. We report a case of long-standing raised intracranial hypertension (ICT) that presented with deteriorating vision in both eyes. Magnetic resonance (MR) imaging of the brain and cerebral angiography showed blockage of superior saggital sinus and sigmoid sinuses with bilateral dural arteriovenous fistulae (DAVF) formation.

Adult↗
PubMed1999

A study of 'crisis cards' in a community psychiatric service.

OBJECTIVE: 'Crisis cards' state patients' treatment details and preferences in anticipation of a later occasion when the patient might be too ill to express them directly. We assessed the feasibility of introducing 'crisis cards', or a collaborative form of them, 'joint crisis plans', into a sectorized community psychiatric service. METHOD: All patients with a psychosis and at high risk of crisis were invited to participate. Follow-up examined patients' satisfaction and how the cards were used. RESULTS: In total, 106 eligible patients were identified and offered a card, and 40% agreed to participate. Patients with an affective psychosis, past suicide attempts and less frequent admissions were over-represented among those who agreed to take part. Patients chose to include a wide range of information. For participants, admissions fell by 30% in the follow-up year. CONCLUSION: Crisis cards serve both a 'manifest', practical function (to provide important information when the patient is too ill to do so) and a 'latent' psychological one (positive effects on the patient's attitude to self, their illness and treatment, and their relationship with the clinical team).

Adult↗
PubMed1999

An evaluation of an Australian videoconferencing project for child and adolescent telepsychiatry.

A user satisfaction survey of videoconferencing services for child and adolescent mental health was carried out over a two-year period in Victoria, Australia. The aims of the survey were to evaluate key utilization areas, effect on professional practice, and advantages and disadvantages of the videoconferencing service. Eighty questionnaires were sent out and 58 (73%) were returned. Consultations were reported as the most frequent use of videoconferencing equipment (62%), followed by clinical use (59%), supervision (36%), teaching (19%) and administration (14%). Fifty-seven per cent of respondents reported that videoconferencing had affected professional practice. Advantages of the services included cost savings (52%) while disadvantages included technological problems (40%). The findings show the benefits of videoconferencing for improving the delivery of mental health care in rural Australia.

Adolescent↗
PubMed1999

Research on physical activity and health among people with disabilities: a consensus statement.

Research is required to advance the understanding of issues related to the effect of physical activity on health and disease prevention among people with disabilities. This report is the result of a consensus process using selected experts in health and exercise. The purpose of the consensus conference was to identify research priorities for physical activity and health among people with disabilities. Priorities were established by 30 participants, who were selected by the principal investigators to achieve balance in the areas of engineering, epidemiology, medicine, nutrition, exercise physiology, and psychology. Experts summarized relevant data from their research and from comprehensive review of the scientific literature on the topic areas chosen for the conference. Public commentary was provided by participants in the 1996 Paralympic Congress. Panel members discussed openly all material presented to them in executive session. Commentary from open discussion periods were recorded and transcribed. Selected panelists prepared first drafts of the consensus statements for each research priority question. All of these drafts were distributed to the panelists and pertinent experts. The documents were edited by the drafting committee to obtain consensus. This research priority setting process revealed that greater emphasis must be placed on determining the risks and benefits of exercise among people with disabilities. Exercise must be studied from the perspective of disease prevention while mitigating risk for injury. Five areas were identified as focal points for future work: epidemiological studies; effects of nutrition on health and ability to exercise; cardiovascular and pulmonary health; children with disabilities; and accessibility and safety of exercise programs. As people with disabilities live longer, the need for addressing long-term health issues and risk for secondary disability must receive greater attention. As a consequence of the consensus process, specific recommendations for future research regarding the impact of exercise on the health and quality of life of persons with disabilities were defined.

Cardiovascular Diseases↗