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Biomedical subjects

A Armstrong

Publications and source records attributed to A Armstrong.

At least 37 records · Page 2Linked to original sources
PubMed1998

Predictors of performance on the National Board of Medical Examiners obstetrics and gynecology subject examination.

OBJECTIVE: To examine the correlation among the National Board of Medical Examiners subject examination, the US Medical Licensure Examination step 1 scores, and grade point average and to determine if poor performance could be predicted by the US Medical Licensure Examination step 1 score and grade point average. METHODS: The subject examination scores of 148 third-year medical students were compared with their US Medical Licensure Examination step 1 scores and grade point averages. Scores below the 20th percentile were defined as poor performance. RESULTS: There was a significant correlation between the US Medical Licensure Examination score and the subject examination score (r = .6, P < .001). The correlation with grade point average was also significant (r = .57, P < .001). CONCLUSION: The US Medical Licensure Examination step 1 performance, grade point average, and performance on the subject examination are all correlated. However, use of the US Medical Licensure Examination step 1 scores and grade point averages to identify all students at risk was associated with a high false-positive rate at our institution.

Certification↗
PubMed1998

Age-related pregnancy rates in GIFT patients.

OBJECTIVE: Fecundity and fertility decline with increasing age beginning as early as age 30 and decrease more precipitously after age 40. The purpose of this study was to determine if pregnancy rates of patients attempting gamete intrafallopian transfer (GIFT) are lower for women between the ages of 35 and 40. METHODS: A retrospective chart review was performed to assess the age-specific pregnancy rates for patients in our GIFT program. We report the results of GIFT at Walter Reed Army Medical Center and the National Naval Medical Center during the period from July 1, 1994, to July 1, 1995. RESULTS: Fifty-six women aged 21 to 39 underwent one to three cycles of gamete intrafallopian transfer. The 72 tubal transfers performed resulted in 25 pregnancies (34.7% pregnancy rate per transfer). CONCLUSIONS: In this series, pregnancy rates did not differ significantly in women older than 35 years versus women younger than 35 years. The number of eggs collected decreased significantly with increasing age but was not significantly different between pregnant and nonpregnant patients. Previous reports demonstrate a clear decline in fertility and poor pregnancy rates with assisted reproductive technology in older women. We did not find age-related differences in pregnancy rates among women younger than 40 years undergoing GIFT during the period studied.

Adult↗
PubMed1997

Reduced calcium dialysate in CAPD patients: efficacy and limitations.

BACKGROUND: The increasing use of 'reduced calcium' dialysate in CAPD patients treated with calcium-based phosphate binders has raised concerns that this could lead to negative calcium balance, worsening hyperparathyroidism, and osteopenia. METHODS: The present study was conducted to examine the possibilities (a) that 1.25 mM calcium dialysate leads to negative calcium balance and worsening hyperparathyroidism, and (b) that conversely 1.25 mM calcium dialysate is still too high for some patients. We studied 22 patients who, after a 2-month run in using 1.75 mM calcium dialysate and aluminium hydroxide binders, entered a 3-month phase of 1.25 mM calcium dialysate with continuation of aluminium hydroxide as the sole phosphate binder. The patients then entered a final 9-month phase in which dialysate calcium remained at 1.25 mM and calcium carbonate was substituted for aluminium hydroxide and progressively titrated to achieve optimum phosphate control. RESULTS: During the initial 3-month period, parathyroid hormone increased from 259, range 11-1149 to 405, range 16-1318 pg/ml (P = 0.0001) and ionized calcium decreased from 1.17 +/- 0.06 to 1.11 +/- 0.08 mM (P = 0.0004). The subsequent 9-month phase was associated with return of parathyroid hormone to baseline levels. Further dialysate calcium reduction to 0.6 mM was implemented in the four patients who became hypercalcaemic. CONCLUSION: This study has clearly shown that reduction of dialysate calcium to 1.25 mM can be harmful to CAPD patients if oral calcium availability is inadequate. It has also shown that dialysate calcium at 1.25 mM is a compromise, with increased risk of hyperparathyroidism if calcium intake is too low and, conversely, risk of hypercalcaemia and unacceptable increases of the Ca x Pi product in a minority of patients. At these extremes there is a need for a high-calcium dialysate (1.75 mM) and a very low-calcium dialysate (0.6 mM or less), to optimize management.

Adult↗
PubMed1997

Characterization of a human papillomavirus type 16 variant-dependent neutralizing epitope.

We have determined that three type-specific and conformationally dependent monoclonal antibodies, H16.E70, H16.U4, and H16.V5, neutralize pseudotype human papillomavirus type 16 (HPV16) virions in vitro. H16.U4 and H16.V5 neutralized pseudotype virions derived from the German HPV16 variant 114K and the Zairian variant Z-1194 with equal efficiency. In contrast, neutralization of Z-1194 pseudotype virions by H16.E70 was two orders of magnitude weaker than neutralization of 114K pseudotype virions. This difference correlated with enzyme-linked immunosorbent assay reactivity of H16.E70 to L1 virus-like particles of the two variants. A substitution at residue 282 of L1 was responsible for this differential reactivity, suggesting that this residue constitutes part of the H16.E70 epitope.

Antibodies, Monoclonal↗
PubMed1996

Virus-like particles of bovine papillomavirus type 4 in prophylactic and therapeutic immunization.

Virus-like particles were produced in insect cells containing either the L1 and L2 capsid proteins of bovine papillomavirus type 4 (BPV-4) or only the L1 protein. Both preparations of VLPs proved to be extremely effective prophylactic vaccines. Thirteen of 15 calves immunised with either L1-L2 VLPs or L1-VLPs were refractory to experimental challenge with high doses of BPV-4 and did not develop papillomas, while 9 of 10 control animals developed multiple oral papillomas. VLPs were not efficient as therapeutic vaccine in calves with established papillomas, although VLP-vaccinated animals appeared to undergo tumour regression more rapidly than nonvaccinated control animals. Antibody responses in VLP-vaccinated calves were associated with prevention of disease but not with regression of papillomas. Thus prophylactic VLP vaccination is effective in preventing disease in this model of mucosal papillomavirus infection. VLPs and native virus share at least some conformational epitopes, as shown by the cross-reactivity of their antibodies.

Animals↗
PubMed1993

An evaluation of a logbook for trainees in accident & emergency medicine in the United Kingdom: senior consultant opinion.

A previous paper from the Merseyside Group of Senior Registrars in Accident & Emergency Medicine examined the desirability of a logbook for Higher Specialist Training (HST) in accident & emergency medicine in the United Kingdom and its principal ingredients (Luke et al., 1991). A survey of 100 senior registrars and recently appointed consultants in the specialty identified the main issues of importance to the majority of respondents e.g. certification in advanced cardiac and trauma life support, a minimum of three years in the specialty before appointment as senior registrar and certain key secondments. In this paper, more senior consultants in the specialty were surveyed and a resounding majority concurred with the preferences of their junior colleagues. The findings are discussed and the implications for a future curriculum for postgraduate training in A&E medicine are explored.

Attitude of Health Personnel↗
PubMed1991

Physiological and developmental implications of motor unit anatomy.

There is increasing evidence that the architectural design and arrangement of the fibers within a motor unit have important physiological and developmental ramifications. Limited data, however, are available to directly address this issue. In the present study the physiological properties of one motor unit in each of seven cat tibialis anterior (TA) muscles were determined. Each of these units then was repetitively stimulated to deplete the glycogen in all muscle fibers within the unit. Subsequently, the length, type of ending, and spatial distribution of fibers sampled from these physiologically and histochemically typed motor units were determined. Four fast fatigable (FF), one fast, fatigue resistant (FR), and two slow (S) motor units (MU) were studied. The samples consisted of all those glycogen-depleted fibers (9-27) contained within a single fascicle or a circumscribed area of each of the motor unit territories. The mean fiber lengths for the two slow motor units were 35.9 and 45.5 mm. The mean fiber lengths for the fast motor unit samples ranged from 8.8 to 48.5 mm. Some fibers of both the fast and slow units reached lengths of 58 mm. Most of the fibers in the slow units extended the entire distance between the proximal and distal musculotendinous planes, had relatively constant cross-sectional areas, and terminated at the tendon as blunt endings. In contrast, the majority of the fibers in the fast units terminated intrafascicularly at one end, and the cross-sectional area decreased progressively along their lengths, that is, showed a tapering pattern for a significant proportion of their lengths. Therefore, the force generated by units that end midfascicularly would appear to be transmitted to connective tissue elements and/or adjacent fibers. All fibers of a fast unit within a fascicle were located at approximately the same proximo-distal location. Thus, developmentally the selection of muscle fibers by a motoneuron would seem to be influenced by their spatial distribution. The architectural complexities of motor units also have clear implications for the mechanical interactions of active and inactive motor units. For example, the tension capabilities of a motor unit may be influenced not only by the spatial arrangement of its own fibers, but also by the level of activation of neighboring motor units.

Animals↗
PubMed1991

A comparative study of the 'FDA' and 'USDA' methods for the detection of Listeria monocytogenes in foods.

Nineteen laboratories across Canada took part in a comparative study of the 'FDA' and 'USDA' methods for the detection of Listeria monocytogenes in foods and environmental samples. The results show that the enrichment period of the FDA method can be shortened from 7 to 2 days without substantially reducing the number of positive samples. With a limited number of samples, the USDA method proved to be slightly more efficient in isolating L. monocytogenes than the FDA method. Fraser broth, in principle, proved to be useful as a screening tool but is not very selective. Oxford agar and lithium chloride-phenylethanol-moxalactam medium were better than modified McBride's agar in isolating this microorganism.

Agriculture↗
PubMed1991

An evaluation of a logbook for trainees in accident and emergency medicine in the United Kingdom.

The ideal requirements of a logbook for trainees in accident and emergency medicine in the United Kingdom were sought by means of a postal survey of 100 Senior Registrars and recently-appointed Consultants in the specialty. Sixty-two replies were received. An overwhelming majority supported ACLS and ATLS certification, as well as formal training in Management/Clinical Budgeting skills, the use of Information Technology, dealing with medicolegal issues and Disaster Planning. Secondments to General Practice, Regional Poisons Centres and the Emergency Services were similarly recommended. A total of 71% (42 responders) approved of a minimum of 3 years experience in an A&E Department before appointment as a Senior Registrar in the specialty. The majority of responders disapproved of acquiring laboratory-based skills. The results of the survey are discussed and suggestions for the possible role of a logbook are made.

Certification↗
PubMed1991

The phenomenology of Cushing's syndrome: one patient's account.

Cushing's syndrome caused by ectopic secretion of adrenocorticotropic hormone (ACTH) is often a serious disease and a diagnostic dilemma. In the reported patient, the source of ACTH proved to be a benign pulmonary carcinoid tumor. The patient describes his trying experiences through the six months from initial diagnosis to definitive therapy.

Carcinoid Tumor↗
PubMed1990

Effects of Acid stress on aerobic decomposition of algal and aquatic macrophyte detritus: direct comparison in a radiocarbon assay.

Radiolabeled phytoplankton and macrophyte lignocelluloses were incubated at pHs 4 and 7 in water from a naturally acidic freshwater wetland (Okefenokee Swamp; ambient pH, 3.8 to 4.2), a freshwater reservoir (L-Lake; pH 6.7 to 7.2), and a marine marsh (Sapelo Island; pH approximately 7.8). The data suggest that acidity is an important factor in explaining the lower decomposition rates of algae in Okefenokee Swamp water relative to L-Lake or Sapelo Island water. The decomposition of algal substrate was less sensitive to low pH ( approximately 5 to 35% inhibition) than was the decomposition of lignocellulose ( approximately 30 to 70% inhibition). These substrate-dependent differences were greater and more consistent in salt marsh than in L-lake incubations. In both freshwater sites, the extent to which decomposition was suppressed by acidity was greater for green algal substrate than for mixed diatom or blue-green algal (cyanobacteria) substrates. The use of different bases to adjust pH or incubation in a defined saltwater medium had no significant effect on substrate-dependent differences. Although pH differences with lignocellulose were larger in marine incubations, amendment of lakewater with marine bacteria or with calcium, known to stabilize exoenzymes in soils, did not magnify the sensitivity of decomposition to acid stress.

Journal Article↗
PubMed1990

Increased sensitivity of the rapid hydrophobic grid membrane filter enzyme-labeled antibody procedure for Escherichia coli O157 detection in foods and bovine feces.

Several strains of Escherichia coli O157:H7 artificially inoculated into vegetables and dairy products were recovered on hydrophobic grid membrane filters and enumerated by an enzyme-labeled antibody assay. The mean of the recoveries from 12 fresh vegetables was 108.8%, whereas that from 10 dairy products was 93.2%. Modified tryptic soy broth at 43 degrees C with shaking at 100 rpm provided optimum recovery of the organism from meat, with a sensitivity of less than or equal to 1 CFU/g, which is 10 times more sensitive than direct plating. The method performed equally well with vegetable and dairy products. Tryptic soy broth, however, under the same conditions gave the best results for fecal samples. Of 22 asymptomatic dairy cattle, reported as having positive Brucella titers when assayed with polyclonal antibodies, eight were found to contain E. coli O157 in their feces as demonstrated by the enzyme-labeled antibody assay by using monoclonal antibodies. This finding may explain some of the false-positive Brucella tests.

Animals↗