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Biomedical subjects

T Wright

Publications and source records attributed to T Wright.

At least 73 records · Page 4Linked to original sources
PubMed1996

Cervical precancer detection using a multivariate statistical algorithm based on laser-induced fluorescence spectra at multiple excitation wavelengths.

A portable fluorimeter was developed and utilized to acquire fluorescence spectra from 381 cervical sites in 95 patients at 337, 380 and 460 nm excitation immediately prior to colposcopy. A multivariate statistical algorithm was used to extract clinically useful information from tissue spectra acquired in vivo. Two full-parameter algorithms were developed using tissue fluorescence emission spectra at all three excitation wavelengths (161 excitation-emission wavelength pairs) for cervical precancer (squamous intraepithelial lesion [SIL]) detection: a screening algorithm that discriminates between SIL and non-SIL with a sensitivity of 82 +/- 1.4% and specificity of 68 +/- 0.0%, and a diagnostic algorithm that differentiates high-grade SIL from non-high-grade SIL with a sensitivity and specificity of 79 +/- 2% and 78 +/- 6%, respectively. Multivariate statistical analysis was also employed to reduce the number of fluorescence excitation-emission wavelength pairs needed to redevelop algorithms that demonstrate a minimum decrease in classification accuracy. Two reduced-parameter algorithms that employ fluorescence intensities at only 15 excitation-emission wavelength pairs were developed: the screening algorithm differentiates SIL from non-SIL with a sensitivity of 84 +/- 1.5% and specificity of 65 +/- 2% and the diagnostic algorithm discriminates high-grade SIL from non-high-grade SIL with a sensitivity and specificity of 78 +/- 0.7% and 74 +/- 2%, respectively. Both the full-parameter and reduced-parameter screening algorithms discriminate between SIL and non-SIL with a similar specificity (+/-5%) and a substantially improved sensitivity relative to Pap smear screening. A comparison of the full-parameter and reduced-parameter diagnostic algorithms to colposcopy in expert hands indicates that all three have a very similar sensitivity and specificity for differentiating high-grade SIL from non-high-grade SIL.

Algorithms↗
PubMed1996

Isozymes of superoxide dismutase from Aloe vera.

Extracts from the parenchymatous leaf gel and the rind of the Aloe vera plant (Aloe barbadensis Miller) were shown to contain seven electrophoretically-identifiable superoxide dismutases (SODs). The chromatographic elution profiles and the migration of these bands on native polyacrylamide gel electrophoresis (PAGE), for both the gel and rind, are quite similar. Two of these seven activities are insensitive to cyanide treatment, suggesting that they are mangano-SODs. The other five activities are sensitive to cyanide treatment, but insensitive to azide treatment and are presumed to be cupro-zinc SODs. All of the seven proteins appear to be homodimers with apparent native molecular masses centered at approximately 32 and 42 kD as indicated by SDS-PAGE and gel-filtration (FPLC) chromatography. The specific activities of SODs in the A. vera rind and gel are comparable to those of spinach leaves and of rabbit liver.

Aloe↗
PubMed1996

Adult acute leukemia: hand mirror cell variant.

Two patients with numerous hand mirror cells in the bone marrow were investigated by morphologic, cytochemical, immunohistochemical, flow cytometric, cytogenetic, and gene rearrangement analysis. Both demonstrated a mixed immunophenotype with expression of myeloid and T-lymphoid features. Interestingly, both strongly expressed CD2 (adhesion molecule) and CD7. Review of the literature uncovered additional cases of acute mixed leukemia--hand mirror variant with strong expression of CD2, CD7, and CDIIb, suggesting a unique subset. Under normal physiologic conditions lymphoid cells and monocytes assume a hand mirror configuration when adhesion molecules (i.e., CD2, CDIIb) are triggered by their corresponding ligands. Evidently not all acute leukemias with surface adhesion molecules form hand mirrors, which suggests an additional stimulatory event. The presence of adhesion molecules on these activated cells is important to homing, trafficking, spread of the malignant cells, clinical course, prognosis, and treatment. Therefore all HMC cases require detailed analysis to ensure accurate diagnosis. In-depth evaluation of such cases should give new insights into clinical presentation, prognosis, and treatment of these unusual cases.

Adult↗
PubMed1996

Continuous negative extrathoracic pressure in neonatal respiratory failure.

OBJECTIVE: In uncontrolled clinical trials, negative extrathoracic pressure has been shown to be an effective respiratory support. We aimed to assess its role in the context of current neonatal intensive care. DESIGN: A randomized controlled trial, with sequential analysis of matched pairs of infants. Matching was undertaken by stratified randomization from 15 groups divided according to gestational age, oxygen requirement, and whether patients were intubated at 4 hours of age. SETTING: Two neonatal intensive care units. PATIENTS: Two hundred forty-four patients (birth weight 1.53 +/- 0.69 kg (mean +/- SD); gestational age 30.4 +/- 3.5 weeks) with respiratory failure. INTERVENTIONS: Patients were randomized at 4 hours of age to receive either standard neonatal intensive care, or standard care plus continuous negative extrathoracic pressure (CNEP, -4 to -6 cmH2O) applied within a purpose-designed neonatal incubator. OUTCOME SCORES: Clinical scores were calculated for each infant at 56 days of age, or death if earlier. Scores included measures for mortality, respiratory outcome, the presence of cerebral ultrasound abnormalities, patent arterial duct, necrotizing enterocolitis, and retinopathy. The treatment given for the higher score for each pair was recorded and the cumulative net number of pairs favoring CNEP plotted in the sequential analysis to provide an ethical early termination strategy. Individual components of the outcome score and other secondary measurements were analyzed on completion of the trial. RESULTS: The sequential analysis reached a decision boundary after 122 out of a possible maximum of 124 pairs were completed. The overall outcome score showed an overall significant benefit for CNEP. Secondary analysis showed that the use of CNEP was associated with an increase in mortality, cranial ultrasound abnormalities, and pneumothoraces, which were not statistically significant. However, 5% fewer patients were intubated (95% confidence interval [CI], 0-10), and the total duration of oxygen therapy among surviving infants at 56 days was lower (20.5 days, compared with 38.9 in controls; difference 18.4 days, 95% CI 3.8 to 33.0). Among all infants, the mean total duration of oxygen therapy was 18.3 days among CNEP-treated infants compared with 33.6 days among the controls (difference -15.3 days, 95% CI -0.2 to -30.4). This reduction in mean levels is entirely attributable to substantially fewer patients requiring prolonged oxygen therapy, the median duration of treatment being very similar in the two groups. As a result, commensurately fewer surviving infants showed chronic lung disease of prematurity. CONCLUSIONS: The use of continuous negative pressure improves the respiratory outcome for neonates with respiratory failure.

Female↗
PubMed1996

Cervical human papillomavirus infection and intraepithelial neoplasia: a review.

Cervical human papillomavirus (HPV) infections and intraepithelial neoplasias are precursors to cervical cancer, the second most common cancer in women worldwide. HPV satisfies the epidemiologic criteria for causality; the role of other cofactors is under study. Natural history studies show that most low-grade lesions (productive HPV infections) regress or persist, whereas high-grade lesions (those with integrated HPV DNA) progress. Immunobiologic studies demonstrate that infection peaks in the early 20s, leading to a 10- to 20-year period of persistent infection, before finally progressing to a preinvasive or invasive lesion. Papanicolaou (Pap) screening has lowered the morbidity and mortality from cervical cancer in every country in which screening programs have been introduced. The diagnostic strategy for an abnormal Pap smear includes colposcopy; the role of HPV DNA testing in screening or diagnosis remains unclear. Patients are treated with cervical ablation, cone biopsy, or chemopreventive agents. Efforts to strengthen screening and prevention, as well as new directions for research, are needed.

Female↗
PubMed1995

In vivo assessment of catheter-tip PO2 sensor: sampling lumen fabrication.

Fabrication of the sampling lumen of an intra-arterial PO2 sensor is performed in standard catheters mechanically or by laser. Clinical evaluation is performed with respect to catheter insertion, complications, accuracy of oxygen sensor data and fibrin deposition on the catheter surface. The success rate for catheter insertion is 57% for 138 standard and 50% for 74 laser-cut catheters studied. The proportion of catheter failures (blocked or non-reading) is 14% in laser-cut compared with 30% in standard. These differences are not statistically significant at the 5% level. There is no clinically significant difference in sensor accuracy, with 37.5% of results within +/- 0.05 kPa and 80% within +/- 2.0 kPa of simultaneous blood gas values. Drift is within +/- 0.3 kPa h-1 for 78% of monitoring time. Significant errors of recalibration occur in 6% of calibrations. Scanning electron micrographs demonstrate a much smaller sampling lumen in the laser-cut group, but no reduction in fibrin deposition at the site of the sampling hole. The low success rate for catheter insertion is a problem because of cost implications. The accuracy of the system is usually sufficient for clinical purposes, provided the calibration is checked every 4 h.

Catheterization, Peripheral↗
PubMed1995

Evaluating dorsal wrist pain: MRI diagnosis of occult dorsal wrist ganglion.

Fourteen patients with chronic dorsal wrist pain of unknown etiology underwent high-resolution magnetic resonance imaging (MRI) examination formatted to evaluate the scapholunate interval. Ten had MRI evidence that was diagnostic for an occult dorsal wrist ganglion. The average measured 4.7 mm at greatest diameter. Eight of 10 patients had the diagnosis confirmed, 7 at the time of surgery, and 1 at follow-up examination when the ganglion enlarged and was no longer occult. The other two opted for nonoperative management. The positive predictive value of a positive MRI finding for occult dorsal wrist ganglion was 100% in this small series. The use of a properly formatted high-resolution MRI in this patient population was diagnostic for occult dorsal wrist ganglion.

Diagnosis, Differential↗
PubMed1995

Effects of positive and negative pressure ventilation on cerebral blood volume of newborn infants.

The effects of intermittent positive airway and continuous negative extrathoracic pressure ventilation on cerebral blood volume in preterm infants were studied using near infrared spectroscopy. In 12 infants continuous negative extrathoracic pressure caused a median decrease in cerebral blood volume of 0.14 ml/100 ml brain (95% confidence intervals (CI) 0.035-0.280) compared with no respiratory support. Oxygenated and deoxygenated haemoglobin also decreased, implying increased venous drainage as the main effect. In 17 infants intermittent positive pressure ventilation also caused a median reduction in cerebral blood volume of 0.06 ml/100 ml brain (95% CI 0.010-0.115) compared with endotracheal positive airway pressure. Deoxygenated haemoglobin increased by 0.07 ml/100 ml brain (95% CI 0.010-0.100) while oxygenated haemoglobin decreased by 0.10 ml/100 ml brain (95% CI 0.005-0.175). The increase in deoxygenated haemoglobin implies decreased venous drainage and the decrease in oxygenated haemoglobin implies that other factors may also be significant. Heart rate, blood pressure and oxygen saturation were monitored continuously and remained stable.

Blood Gas Analysis↗
PubMed1995

The effect of conformity on stresses in dome-shaped polyethylene patellar components.

Polyethylene stresses were examined in patellar components with convex-shaped articulating surfaces in contact with convex metallic surfaces. Two finite element models were used: 1 with geometry of a newly manufactured component and 1 with geometry of a retrieved patellar component that had worn and deformed so that the contact area was concave. The range of maximum principal stress and the maximum shear stress were more severe in the newly manufactured model than in the model of the retrieved component. These stresses were also more severe than determined previously for models of femorotibial contact. For both patellar models, the von Mises stress was at or near the polyethylene yield stress in most of the contact area, consistent with the large amount of permanent deformation observed on many retrieved patellar components. This suggests that deformation may continue, even when the component's surface has deformed and worn into a concave shape.

Humans↗
PubMed1994

Negative extrathoracic pressure ventilation--evaluation of the neck seal.

The effect of the neck seal used in the application of negative extra-thoracic pressure ventilation was studied using near infrared spectroscopy. Changes in cerebral blood volume (CBV) were monitored during discontinuation of negative pressure and during removal of the neck seal. CBV increased by 0.17 ml 100 ml brain-1 (95% CI +0.0875 to +0.481) when negative pressure was discontinued. Removal of the neck seal had no significant effect on CBV. It is concluded that the neck seal does not cause significant jugular venous occlusion.

Blood Volume Determination↗
PubMed1994

Plasma oxidase assay for screening of myocardial infarction.

The availability of techniques such as surgical reperfusion, angioplasty, and thrombolysis for the treatment of acute myocardial infarction (AMI) has revived interest in seeking an early detectable biochemical marker diagnostic for AMI. Therefore, we investigated whether an unidentified oxidase that is released by activated neutrophils at the onset of AMI could be used as an early diagnostic assay. The conversion by plasma oxidase of 1 microM of adrenaline to 1 microM of adrenochrome represents the plasma oxidase activity (POA) of 1 U/L. Fifty patients suspected of having AMI, 40% of whose electrocardiograms were nondiagnostic for AMI, were admitted to the coronary care unit, and venous blood samples were obtained for determination of the POA and creatine phosphokinase-MB levels. Healthy volunteers (n = 12) served as control subjects, and 8 patients with pneumonia whose leukocyte counts were greater than 15,000 microL were included in the study. In those with AMI (n = 22), as determined by serial creatine phosphokinase-MB, the mean POA (+/- standard error of the mean) was 233 +/- 13 U/L, and in those with angina and no AMI (n = 28) was 127 +/- 5 U/L (P < 0.0001). In the control group, mean POA (+/- standard error of the mean) was 84 +/- 5 U/L (control versus angina; P < 0.01) and for those with infection was 214 +/- 10 U/L. At admission, the creatine phosphokinase-MB was diagnostic for only 12 of the 22 patients with AMI (sensitivity rate of 54%), whereas in 21 of those patients, the POA values were diagnostic for AMI (sensitivity rate of 95%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenochrome↗