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Biomedical subjects

C Harris

Publications and source records attributed to C Harris.

At least 55 records · Page 3Linked to original sources
PubMed2001

Cutaneous neosporosis in two adult dogs on chronic immunosuppressive therapy.

Antemortem diagnosis of generalized ulcerative and pyogranulomatous dermatitis with numerous intralesional tachyzoites was made from skin biopsy specimens from 2 adult dogs on chronic immunosuppressive therapy. A 9-year-old Italian Greyhound was on long-term corticosteroid therapy for the treatment of a lupus-like systemic autoimmune disorder, and a 7-year-old Labrador Retriever had received several months of chemotherapy for lymphosarcoma. The tachyzoites were identified as Neospora caninum by immunoperoxidase immunohistochemistry. Both dogs were treated with clindamycin. Lesions in the Greyhound resolved; however, the Labrador Retriever was euthanized because of evidence of neuromuscular disease, despite improvement of the skin lesions. These 2 cases indicate that cutaneous neosporosis can occur in adult dogs on chronic immunosuppressive therapy. The disease may result from reactivation of a congenital infection and/or a recently acquired primary infection.

Animals↗
PubMed2001

Assembly of very low density lipoproteins in mouse liver: evidence of heterogeneity of particle density in the Golgi apparatus.

The assembly of very low density lipoproteins (VLDL) by hepatocytes is believed to occur via a two-step process. The first step is the formation of a dense phospholipid and protein-rich particle that is believed to be converted to VLDL by the addition of bulk triglyceride in a second step. Previous studies in our laboratory led us to hypothesize a third assembly step that occurs in route to or in the Golgi apparatus. To investigate this hypothesis, nascent lipoproteins were recovered from Golgi apparatus-rich fractions isolated from mouse liver. The Golgi fractions were enriched 125-fold in galactosyltransferase and contained lipoprotein particles averaging approximately 35 nm in diameter. These lipoproteins were separated by ultracentrifugation into two fractions: d < 1.006 g/ml and d1.006;-1.210 g/ml. The d < 1.006 g/ml fraction contained apolipoprotein B-100 (apoB-100), apoB-48, and apoE, while the d1.006;-1.210 g/ml fraction contained these three apoproteins as well as apoA-I and apoA-IV. Both fractions contained a 21-kDa protein that was isolated and sequenced and identified as major urinary protein. Approximately 50% of the apoB was recovered with the denser fraction. To determine if these small, dense lipoproteins were secreted without further addition of lipid, mice were injected with Triton WR1339 and [(3)H]leucine, and the secretion of apoB-100 and apoB-48 into serum VLDL (d < 1.006 g/ml) and d1.006;-1.210 g/ml fractions was monitored over a 2-h period. More than 80% of the newly synthesized apoB-48 and nearly 100% of the apoB-100 were secreted with VLDL. These studies provide the first characterization of nascent lipoproteins recovered from the Golgi apparatus of mouse liver. We conclude that these nascent hepatic Golgi lipoproteins represent a heterogeneous population of particles including VLDL as well as a population of small, dense lipoproteins. The finding of the latter particles, coupled with the demonstration that the primary secretory product of mouse liver is VLDL, suggests that lipid may be added to nascent lipoproteins within the Golgi apparatus.

Animals↗
PubMed2001

HIV testing.

Explore the source record for details and available documents.

Female↗
PubMed2000

Dominant negative mutation of the hematopoietic-specific Rho GTPase, Rac2, is associated with a human phagocyte immunodeficiency.

Rho GTPases control a variety of cellular processes, including actin polymerization, integrin complex formation, cell adhesion, gene transcription, cell cycle progression, and cell proliferation. A patient is described who has recurrent infections and defective neutrophil cellular functions similar to those found in Rac2-deficient mice. Molecular methods were used to clone the expressed Rac2 cDNA from this patient, and a single base pair change (G-->A at nucleotide 169) in the coding sequence was identified. This results in an asparagine for aspartic acid mutation at amino acid 57 (D57N), a residue that is involved in nucleotide binding and is conserved in all mammalian Rho GTPases. The cloned cDNA was then introduced into normal bone marrow cells through retrovirus vectors, and neutrophils expressing this mutant exhibited decreased cell movement and production of superoxide in response to fMLP. The expressed recombinant protein was also analyzed biochemically and exhibited defective binding to GTP. Functional studies demonstrated that the D57N mutant behaves in a dominant-negative fashion at the cellular level. The syndrome of Rac2 dysfunction represents a human condition associated with mutation of a Rho GTPase and is another example of human disease associated with abnormalities of small G protein signaling pathways. (Blood. 2000;96:1646-1654)

3T3 Cells↗
PubMed2000

Sensitivity of a clinical scale of balance and gait in frail nursing home residents.

PURPOSE: The purpose of this paper was to describe this application, and to assess the sensitivity of the application when evaluating clinical interventions for improving balance and gait. METHODS: The records of fifteen consecutive patients referred to physical therapy for mobility problems or recent falls were reviewed for this study. The subjects were evaluated upon initial referral to physical therapy and after 30 days of treatment. Treatment was developed around the problems noted on initial evaluation and applied 5 days/week for 20 sessions. RESULTS: A Wilcoxon signed-rank comparison of the initial and 30 day re-evaluation of the balance and the gait assessment indicated that significant improvement had occurred in the balance scores (Z = -3.20, p = 0.001) and the gait scores (Z = -2.82, p = 0.005) in this group. CONCLUSION: These assessments are sensitive to clinical improvements in mobility among frail elders.

Accidental Falls↗
PubMed2000

Concentrations of suspended particulate organic carbon in the tidal Yorkshire Ouse River and Humber Estuary.

Data are presented for particulate organic carbon (POC) and particulate nitrogen (PN) concentrations in the Humber Estuary and tidal River Ouse Estuary. The POC data were derived from approximately monthly surveys and are consistent with data reported for suspended particulate matter (SPM) in the non-tidal River Ouse (the freshwater river) and with SPM, or bed sediments, in estuarine ecosystems such as the Mississippi, Delaware, San Francisco Bay, Tolo Harbour, the Vellar Estuary and Cochin Backwater, as well as the Loire, Gironde, Ems and Tamar Estuaries. Relative to the dry weight of SPM, the Humber-averaged organic carbon and nitrogen percentages during the year February 1995-March 1996 were 2.6 +/- 0.6% (mean and S.D.) and 0.21 +/- 0.04%, respectively. The ratio of Humber-averaged POC to Humber-averaged PN was 13 +/- 3. Higher POC levels were observed near the Humber's mouth and in the adjacent coastal zone during 'bloom' conditions, and in the upper estuarine reaches during large, winter and springtime freshwater inflows. At these times of high runoff, the POC content of SPM increased progressively up-estuary from the coastal zone to the tidal River Ouse. When inflows became very low, during late spring to early autumn of 1995, both the freshwater-saltwater interface (FSI) and the strengthening turbidity maximum (TM) moved further up-estuary and the POC content of SPM in the upper reaches of the Ouse became lower compared with that immediately down-estuary. This led to a poorly defined POC maximum near the confluence of the Humber, Ouse and Trent, before POC eventually decreased again towards the coastal zone. The lower POC contents in the upper estuarine reaches of the tidal Ouse may have been partly due to POC respiration by heterotrophic bacteria attached to SPM within the TM, consistent with the severe oxygen depletion observed there during high turbidity, summertime spring tides.

Carbon↗
PubMed2000

Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary.

Results are presented from a campaign of measurements that were undertaken to examine seasonal variability in physical and chemical fluxes and processes within the Tweed Estuary during the period September 1996-August 1997. The study utilised monthly surveys, each of approximately 1 week duration. This article interprets a subset of the salinity, temperature, turbidity [suspended particulate matter (SPM) levels] and chlorophyll a data. Measurements discussed here were obtained throughout the estuary during high-speed transects that covered the region between the tidal river and the coastal zone. Longitudinal distributions of surface salinity depended strongly on freshwater runoff. During high runoff the surface salinity was low and the freshwater-saltwater interface (FSI) was located close to the mouth. The reverse was true at times of low runoff. Salinity stratification was generally strong. During the surveys, river runoff temperatures ranged from approximately 2 to 18 degrees C and coastal waters (approximately 33 salinity) from approximately 6 to 15 degrees C. Turbidity was low throughout the campaign (SPM < 30 mg l(-1)). Because of rapid flushing times (one or two tides), turbidity tended to mix conservatively between river and coastal waters. Higher coastal turbidity was associated with stronger wind events, and higher fluvial turbidity with spate events. Suspended chlorophyll a levels were usually low throughout the estuary (typically < 2 microg l(-1)) and showed large spatial variability. Because of the rapid flushing of the estuary, it is hypothesised that it was not possible for several algal cell divisions to occur before algae were flushed to the coastal zone. A 'bloom' occurred during the May 1997 survey, when chlorophyll a levels reached 14 microg l(-1). Higher chlorophyll a concentrations at that time occurred at very low salinities, indicating that these waters and algae were largely fluvially derived, and may have resulted from increasing springtime solar irradiation.

Chlorophyll↗
PubMed2000

Comparison of open, percutaneous, and translaryngeal tracheostomies.

INTRODUCTION: With 3 tracheostomy techniques currently available, controversy exists regarding which is safest and most economical. Percutaneous (PDT) and the new translaryngeal (TLT) tracheostomies are cited as more cost-effective than the traditional open surgical procedure because they are bedside techniques. Our objective was to compare the perioperative and postoperative complications of the 3 techniques. STUDY DESIGN: This was a prospective trial involving 100 consecutive patients who underwent tracheostomy between April and December of 1997 at the London Health Sciences Centre and St Joseph's Health Centre in London, Canada. RESULTS: Fifty open tracheostomies were performed. Indications included prolonged ventilation (n = 42), airway protection (n = 5), pulmonary hygiene (n = 2), and sleep apnea (n = 1). A tension pneumothorax was the one significant intraoperative complication. Fifteen postoperative complications occurred, most notable of which was a 2-L hemorrhage at 24 hours. Thirty-seven TLTs were performed, 20 in patients with coagulopathy. Indications were prolonged intubation (n = 27), airway protection (n = 9), and pulmonary hygiene (n = 1). One intraoperative complication of accidental decannulation occurred. One postoperative complication, a pretracheal abscess, occurred in a decannulated transplant patient 2 weeks after the procedure. Thirteen PDTs were performed. Indications were prolonged intubation (n = 6), airway protection (n = 6), and tracheal toilet (n = 1). No significant complications occurred. CONCLUSIONS: TLT and PDT have fewer complications than the traditional open technique. TLT appears to have the greatest utility in the coagulopathic patient.

Cost-Benefit Analysis↗
PubMed2000

Lactic acidosis associated with stavudine administration: a report of five cases.

Type "B" lactic acidosis has been described in patients receiving the nucleoside analogs zidovudine, didanosine, and fialuridine. Lactic acidosis has also been described in 4 patients receiving combination therapy with stavudine and lamivudine. We describe the development of chronic type "B" lactic acidosis in 3 patients receiving stavudine as a single agent and in 2 patients receiving combination therapy with stavudine and either lamivudine or delavirdine, a nonnucleoside analog. All patients presented with abdominal pain, vomiting, and hepatic steatosis. Other signs of mitochondrial toxicity included pancreatitis and myopathy (2 cases). The mean duration of stavudine therapy was 9.4 months, and the mean observed peak lactate level+/-SD was 10.3+/-5 mmol/L. After discontinuation of stavudine treatment, lactic acidosis improved in 4 patients after 4-60 weeks, and 1 patient died. Evaluations for other causes of lactic acidosis, including hypoxemia, malignancy, sepsis, and cardiogenic shock, were negative.

Acidosis, Lactic↗
PubMed2000

Work, psychological well-being and performance.

Evidence is reviewed on work performance as a consequence of both psychological well-being and work stressors. There is evidence that some forms of psychological well-being are related to subsequent in-role performance, although the evidence for a causal influence of work stressors on job performance is much weaker. There is also evidence for relationships between some job stressors or well-being and organizational citizenship behaviours. In general, research conducted at the individual level, indicates only weak or provisional relationships. A small number of recent studies indicate stronger associations between average levels of well-being in an organization and organizational performance. It is concluded that more detailed and specific models of well-being and work performance need to be developed. These models need to be tested using methods that can more easily detect subtle variations in well-being and work performance.

Adaptation, Psychological↗
PubMed2000

If students are not customers, what are they?

The answers to questions about the relationship between faculty and students-including medical students-depend on an understanding of the nature of teaching and the underlying ethical principles of our society. The authors maintain that teaching is purposive, rational, communal, and moral. They assert that Western society is based on the values of liberal democracy and that the key ethical principles for the professions that are derived from those values are autonomy, standard of care, and respect for democratic institutions. There are three candidates for ethical models on which to base the relationship between students and faculty. Two of them (clientism and paternalism) the authors reject. The one that they favor (the fiduciary model) is based on mutual trust and respect, which both students and faculty have responsibilities to maintain. Using that model, the authors conclude that students are, in some aspects, customers of faculty. This student-centered approach is balanced by treating society and other faculty as customers as well. Pathologies in medical education attributed to clientism (such as an obsession with marks and overemphasis on memorization) existed well before medical students were purportedly being treated as customers; perhaps it is not the student who is "broken" but the system in which the student is made to function. Whether students are called customers, clients, knowledge workers, or simply students, faculty must involve them more in shaping their education and in dealing with enduring problems that profoundly affect their learning.

Democracy↗
PubMed2000

Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices.

Electromagnetic Fields↗
PubMed2000

Vertical or asymmetric nystagmus need not imply neurological disease.

AIM: To indicate that congenital idiopathic nystagmus (CIN) and sensory defect nystagmus (SDN) can be vertical or asymmetric in some children. METHODS: Of 276 children presenting with nystagmus for electrophysiological testing, 14 were identified as having CIN or SDN, yet had a nystagmus which was either vertical (n=11) or horizontal asymmetric (n=3). Flash electroretinograms and flash and pattern visual evoked potentials (VEPs) were recorded in all patients. Eye movement assessment, including horizontal optokinetic nystagmus (OKN) testing, was carried out in 11/14 patients. RESULTS: Eight patients (seven with vertical, one with asymmetric horizontal nystagmus) had congenital cone dysfunction. One patient with vertical and another with asymmetric nystagmus had cone-rod dystrophy. One patient with vertical upbeat had congenital stationary night blindness. Two patients (one downbeat, one upbeat nystagmus) had normal electrophysiological, clinical, and brain magnetic resonance imaging findings and were classified as having CIN. One patient with asymmetric nystagmus showed electrophysiological and clinical findings associated with albinism. Horizontal OKN was present in 80% of patients tested, including the three cases with horizontal asymmetric nystagmus. This is atypical in both CIN and SDN, where the OKN is usually absent. CONCLUSIONS: Vertical and asymmetric nystagmus are most commonly associated with serious intracranial pathology and its presence is an indication for neuroimaging studies. However, such nystagmus can occur in children with retinal disease, albinism, and in cases with CIN. These findings stress the importance of non-invasive VEP/ERG testing in all cases of typical and also atypical nystagmus.

Child, Preschool↗
PubMed2000

Patterns and predictors of HIV risk among urban American Indians.

A preliminary survey of HIV risk and service preferences among American Indians residing in the New York metropolitan area included 68 women and 32 men (M age=35.8 years). Overall, the sample was knowledgeable about the mechanisms of HIV transmission, and 58 percent reported having taken an HIV test. However, of the 63 percent who reported sexual activity in the last six months, 73 percent reported engaging in vaginal or anal sex without a condom with at least 1 partner, and 52 percent used condoms none of the time during vaginal and anal sex. Almost half (43 percent) reported alcohol or other drug (AOD) use for non-ceremonial purposes in the last six months. Alarmingly, 44 percent reported lifetime trauma, including domestic violence (20 percent) and physical (29 percent) or sexual (26 percent) assault by a family member or stranger. Bivariate and multivariate analyses indicated trauma and drug use were factors that may place respondents at risk for sexual transmission of HIV. Trauma variables were better predictors of HIV risk behaviors than social cognitive variables providing preliminary support for the use of a postcolonial framework in American Indian HIV studies.

Adolescent↗