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Biomedical subjects

W D Anderson

Publications and source records attributed to W D Anderson.

At least 19 recordsLinked to original sources
PubMed2002

Skin grafts for the salvage of degloved below-knee amputation stumps.

We present a series of six patients in whom a traumatic below-knee amputation was associated with significant degloving, such that there was inadequate local skin to achieve primary stump closure. In each case, skin grafts were used to cover the stump muscle flaps. The patients ranged in age from 21 years to 73 years; the mean hospital stay was 72 days and the mean follow-up was 48 months. Despite an average of five procedures to achieve stump healing and an average of 118 days to first limb fitting, all patients have achieved independent mobility with their prosthesis. All have had minor stump problems necessitating periods of time off their prosthesis. Three patients have required minor stump-revision surgery. The advantages of a below-knee amputation over an above-knee amputation compensate for these problems. The forgiving nature of modern prostheses has contributed to acceptable results in these patients, who had what may previously have been considered insufficiently durable stump cover.

Adult↗
PubMed2000

Adequacy of intracoronary versus intravenous adenosine-induced maximal coronary hyperemia for fractional flow reserve measurements.

BACKGROUND: Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. The most widely used pharmacologic stimulus for maximal coronary hyperemia is adenosine, administered either as a continuous intravenous (IV) infusion or intracoronary (IC) bolus. IV adenosine has more side effects and is more costly than IC adenosine but has a more stable and prolonged hyperemic effect. METHODS: We compared the efficacy of IC and IV adenosine administration for the measurement of FFR in a multicenter trial. Fifty-two patients with 60 lesions underwent determination of FFR with both IV and IC adenosine. IV adenosine was administered as a continuous infusion at a rate of 140 microgram/kg per minute until a steady state hyperemia was achieved. IC adenosine boluses were administered at a dose of 15 to 20 microgram in the right and 18 to 24 microgram in the left coronary artery. FFR was calculated as the ratio of the distal coronary pressure (from pressure guide wire) to the aortic pressure (guide catheter) at maximal hyperemia. RESULTS: A total of 26 left anterior descending, 23 right, 9 left circumflex, and 3 left main coronary arteries were evaluated. Mean percent stenosis for both groups was 55.8% +/- 23.6% (range 0% to 95%), and mean FFR was 0.78 +/- 0.15 (range 0.41 to 0.98). There was a strong and linear correlation between FFR measurements with IV and IC adenosine (R = 0.978, y = 0. 032 + 0.964x, P <.001). The agreement between the 2 sets of measurements was also high, with a mean difference in FFR of -0.004 +/- 0.03. However, a small random scatter in both directions of FFR measurements was noted with 5 lesions (8.3%) where FFR with IC adenosine was higher by 0.05 or more compared with IV infusions, suggesting a suboptimal hyperemic response in these patients. Changes in heart rate and blood pressure were significantly higher with IV adenosine. Two patients with IV, but none with IC adenosine, had severe side effects (bronchospasm and severe nausea). CONCLUSION: These results suggest that IC adenosine is equivalent to IV infusion for the determination of FFR in the majority of patients. However, in a small percentage of cases, coronary hyperemia was suboptimal with IC adenosine.

Adenosine↗
PubMed1999

Intravascular ultrasonic analysis of plaque characteristics associated with coronary artery remodeling.

We sought to determine the patient and plaque characteristics associated with the different forms of arterial remodeling as seen by intravascular ultrasound (IVUS) before coronary intervention. Remodeling in response to plaque accumulation may occur in the form of compensatory enlargement and/or focal vessel contraction. Previous studies report variation in the frequency and form of arterial remodeling. We performed preintervention IVUS imaging on 169 patients. Vessels were categorized as exhibiting compensatory enlargement or focal contraction if the arterial area at the lesion was larger or smaller, respectively, than both proximal and distal reference arterial areas; otherwise the artery was considered not to have undergone significant remodeling. Calcification was assessed and noncalcified plaque density was measured by videodensitometry. Sixty-one of 169 patients (66 narrowings) (46 men and 15 women, age 56+/-11 years) had adequate reference segments. Remodeling occurred in 43 of 66 patients (65%): compensatory enlargement in 27 of 66 (41%) and focal contraction in 16 of 66 (24%). Lesions with focal contraction had significantly smaller arterial area (13.3+/-3.3 vs. 18.1+/-7.0 mm2, p = 0.02) and plaque area (9.5+/-2.8 vs 13.7+/-5.5 mm2, p<0.01). Cross-sectional stenosis was similar (71+/-9% vs. 75+/-10%, p = NS), as was plaque density (p = 0.20), eccentricity, and calcium. Patient age, gender, and lesion location were not related to the form of remodeling. Similarly, history of diabetes, hypercholesterolemia, or hypertension was not predictive. Smoking was the only risk factor associated with focal contraction (p<0.01). Thus, whereas compensatory enlargement appears to be the most common form of coronary artery remodeling, focal contraction occurs more often in smokers.

Coronary Artery Disease↗
PubMed1998

Immigration and ethnicity. Implications for holistic nursing.

International labor migration has increased the day-to-day encounters of persons from different cultural groups. The concept of ethnicity, its historical development, its ambiguity, and its role in the interactions between persons of different cultural groups are explored. The arena of health care for migrants brings to the fore issues of providing culturally competent care. In an ideal world, all nursing care of migrants would be delivered by skilled transcultural nurses; but in the real world, this is not yet the case. A case study of a Mexican migrant woman and a non-Hispanic Midwestern nurse is used as a background for examining the role of ethnicity in determining care needs and expectations and for providing nurses with a perspective that can improve nurse-client collaboration.

Attitude to Health↗
PubMed1996

A review of randomized trials comparing coronary angioplasty and bypass grafting.

Angioplasty and bypass surgery have become standard methods of treating patients with symptomatic coronary atherosclerosis. Although both procedures have been applied to a wide spectrum of patients with acceptable morbidity and mortality, only recently have randomized trials been performed to directly compare their efficacies. In patients with multivessel disease, overall mortality and freedom from myocardial infarction appear to be similar between the two treatment strategies. Primarily due to restenosis, the need for repeat revascularization procedures is significantly greater in patients who initially undergo angioplasty. Accordingly, this difference is most striking in the 1st year of follow-up and diminishes over time. The costs of the two treatment strategies reflect the restenosis problem as well. Although angioplasty initially costs less than bypass surgery, the cost savings largely abate after repeat interventions are performed.

Angioplasty, Balloon, Coronary↗
PubMed1995

The CFC challenge: chillers to replace, retrofit or ?

Health care facilities are planning for changes in regulations regarding chlorofluorocarbon-based refrigerants. These changes are imminent, leaving little time to figure out what to do with equipment using these refrigerants. This article looks at the background of the CFC phaseout program and reviews options available to engineers in assessing their equipment.

Air Conditioning↗
PubMed1994

Monitoring mRNA expression by polymerase chain reaction: the "primer-dropping" method.

We have developed a method to monitor mRNA expression that is based upon the reverse transcriptase-polymerase chain reaction (RT-PCR) and includes multiple sets of primer pairs in coamplification reactions. To observe relative changes in mRNA steady-state levels, each target in a multiplex reaction was amplified to within a predetermined range by using PCR cycle numbers specific for each target. Optimal PCR cycle numbers for target templates were determined by preliminary titration experiments performed using the "primer-dropping" method. By employing this method, the overall amplification reaction was limited, permitting the PCR products to remain within the exponential range of the amplification curve and yet be detectable on ethidium bromide-stained gels. We demonstrated the utility of this method by monitoring the expression kinetics of cyclins A, B1, D1, and E, and of the immediate-early genes c-fos, c-myc, and beta-actin. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was included in the multiplex reactions as an endogenous internal standard to control for variations in product abundances due to differences in individual RT and PCR reaction efficiencies. Changes in gene expression of less than twofold to greater than 75-fold were readily distinguished.

Actins↗
PubMed1993

Ferrous sulfate reduces cimetidine absorption.

A variety of drugs that bind to iron have significant reductions in absorption when coadministered with iron compounds. Cimetidine has a structure that would suggest strong binding to iron ions. In vitro experiments were performed to examine a variety of characteristics of the binding of iron to cimetidine. Further studies were conducted to determine the effect of concurrent administration of ferrous sulfate on cimetidine absorption in an in vivo isolated perfused rat jejunal model of drug absorption. The dose of cimetidine was chosen to represent a human dose of 300 mg, while the ferrous sulfate doses were chosen to represent 150- and 300-mg doses. The higher ferrous sulfate dose completely inhibited cimetidine absorption (P < 0.01), while the lower dose of ferrous sulfate caused a 63% reduction in cimetidine absorption (P < 0.05). In vitro iron in its ferrous from rapidly oxidizes to the ferric form. The ferric form of iron binds to cimetidine and may be the cause of the decreased cimetidine absorption. Care should be taken in prescribing iron supplements with cimetidine.

Animals↗
PubMed1991

Inhibition of contraction of isolated lymphatic ducts by atrial natriuretic peptide.

Atrial natriuretic peptide (ANP) potently relaxes blood vessels but its effect on lymphatic motility is unreported. We studied the effect of ANP, and the smooth muscle relaxing agent nitroprusside (NP), on isolated ovine mesenteric lymphatic ducts. Duct segments were mounted on a myograph, and noncumulative dose-response curves were obtained for the effect of ANP and NP on the rate and force of spontaneous (and norepinephrine-induced) duct contraction. Both ANP (threshold approximately 1 nM) and NP (threshold approximately 10 nM) in a dose-related fashion reduced the frequency and force of contraction of both spontaneously contracting and norepinephrine-stimulated duct segments. ANP may therefore affect interstitial fluid balance through its effect on lymphatic motility.

Animals↗
PubMed1990

Sensitivity of a set of myocardial infarction screening criteria in patients with anatomically documented single and multiple infarcts.

A subset of 3 screening criteria (Q wave greater than or equal to 30 ms in lead aVF, any Q or R wave less than or equal to 10 ms and less than or equal to 0.1 mV in lead V2, and R wave greater than or equal to 40 ms in V1) has been proposed to identify single nonacute myocardial infarcts. Cumulatively, these 3 criteria achieved 95% specificity, and 84 and 77% sensitivities for inferior and anterior myocardial infarcts, respectively, among patients identified by coronary angiography and left ventriculography. This study establishes the true sensitivities of the set of screening criteria in 71 patients with anatomically proven single myocardial infarcts and 32 patients with multiple myocardial infarcts. In the single inferior infarct group, the aVF criterion was 90% sensitive. The V2 criterion (any Q or R wave less than or equal to 10 ms and less than or equal to 0.1 mV) was 67% sensitive in the single anterior infarct group. No single criterion proved sensitive in identifying a posterolateral infarct. The set of screening criteria performed just as well for multiple infarcts as it did for single infarcts, with a cumulative sensitivity of 72%. The overall sensitivity of the screening set in the 103 patients in all groups was 71%.

Adult↗
PubMed1990

Effect of an engineered disulfide bond on the folding of T4 lysozyme at low temperatures.

Equilibrium and kinetic effects on the folding of T4 lysozyme were investigated by fluorescence emission spectroscopy in cryosolvent. To study the role of disulfide cross-links in stability and folding, a comparison was made with a mutant containing an engineered disulfide bond between Cys-3 (Ile-3 in the wild type) and Cys-97, which links the C-terminal domain to the N terminus of the protein [Perry & Wetzel (1984) Science 226, 555]. In our experimental system, stability toward thermal and denaturant unfolding was increased slightly as a result of the cross-link. The corresponding reduced protein was significantly less stable than the wild type. Unfolding and refolding kinetics were carried out in 35% methanol, pH 6.8 at -15 degrees C, with guanidine hydrochloride as the denaturant. Unfolding/refolding of the wild-type and reduced enzyme showed biphasic kinetics both within and outside the denaturant-induced transition region and were consistent with the presence of a populated intermediate in folding. Double-jump refolding experiments eliminated proline isomerization as a possible cause for the biphasicity. The disulfide mutant protein, however, showed monophasic kinetics in all guanidine concentrations studied.

Cross-Linking Reagents↗
PubMed1990

Malignant rhabdoid tumor of the liver. A distinct clinicopathologic entity.

A malignant rhabdoid tumor occurring as a primary hepatic neoplasm in a six-month-old white infant is reported. It was treated by an attempt at total resection involving right hepatic lobectomy and by chemotherapy with cis-platinum, VP-16, and Adriamycin. Despite this, recurrence of the tumor resulted in the girl's death within three months. The neoplasm showed typical light microscopic features of malignant rhabdoid tumor as well as filamentous cytoplasmic inclusions by electron microscopic examination and staining for both cytokeratin and vimentin by immunohistochemistry. The classic clinicopathologic features of this tumor support the concept that malignant rhabdoid tumors similar to those of the kidney may occur in extrarenal sites.

Female↗
PubMed1989

Giant lymph node hyperplasia of the hyaline vascular type with plasmacytoid T-cells and presentation in infancy.

Giant lymph node hyperplasia is uncommon in children and is exceptionally rare in infancy. The authors report a case of giant lymph node hyperplasia that presented as a right supraclavicular mass in an asymptomatic two-month-old female infant. Clinically, the mass was thought to be either a lipoma or a cystic hygroma, and it was followed for more than two years before excision. Histologically, the tumor showed classic features of giant lymph node hyperplasia of the hyaline vascular type but also showed many clusters of plasmacytoid T-cells.

Capillaries↗
PubMed1989

Comparative mucosal microvasculature of the mammalian stomach.

The comparative morphology of the gastric mucosal microvasculature was investigated using the corrosion casting technique. The vascular pattern consisted of a hexagonally arranged capillary plexus surrounding the gastric glands and terminating in venules running perpendicular to the mucosal axis. Vessels of the pyloric antrum demonstrated an acute angle between capillaries and venules, whereas vessels of the gastroduodenal junction changed from a honeycomb pattern to a leaf-like arrangement.

Animals↗
PubMed1989

Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). I. Gross anatomical distribution.

A morphological study of the intracranial vessels of the Black bear (Ursus americanus) was undertaken. The object was to provide basic information related to the vascular pattern in these animals as compared with other carnivores and with the human. Vascular casts were prepared from 6 animals. The vasculature of the brain disclosed patterns comparable to other species previously studied.

Animals↗