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Biomedical subjects

D A Lynch

Publications and source records attributed to D A Lynch.

At least 19 recordsLinked to original sources
PubMed1998

Imaging of asthma and allergic bronchopulmonary mycosis.

The chest radiograph of the patient with asthma is characterized by bronchial wall thickening and hyperinflation. On CT scanning of patients with asthma one may see airway wall thickening, thickened centrilobular structures, and focal or diffuse hyperlucency. Apparent bronchial dilation may be seen, but the diagnosis of bronchiectasis should be made with caution. Quantification of changes in the airway wall and lung parenchyma may be valuable in understanding the mechanisms of asthma and in evaluating the effects of treatment. Central bronchiectasis occurs in most, but not all, cases of ABPA. Patchy airspace opacity may be the sole radiologic manifestation of ABPA in some cases. Other fungi can rarely cause a similar syndrome. The challenge for the radiologist evaluating the images of a patient with asthma is to find complications, such as ABPA, or alternative diagnoses.

Aspergillosis, Allergic Bronchopulmonary↗
PubMed1998

Diagnosis of Trichomonas vaginalis in adolescent females: InPouch TV culture versus wet-mount microscopy.

PURPOSE: This study compared the InPouch TV culture to wet-mount, Diamond's culture medium, and Papanicolaou (Pap) smear for the diagnosis of trichomonas infection in sexually active adolescents. METHODS: A total of 467 subjects were recruited among 12-18-year-old girls who received pelvic examinations at two urban adolescent clinics. All girls were tested by wet-mount and InPouch TV. In addition 339 of 467 had cultures in Diamond's medium and 366 of 467 had Pap smears. Specimens were collected for InPouch TV and Diamond's cultures and read at 24-48 h and 5 days, and in the case of Diamond's cultures, also at 7 days. In a subset of subjects (268 of 467) who had all four tests done, sensitivities and specificities were calculated using Diamond's culture as the "gold standard." RESULTS: In the 467 subjects, 73 (15.6%) tested positive for trichomonas by at least one method. In the subset with all four tests done, sensitivities of the wet-mount and InPouch TV were 36% and 81%, respectively; while that of the Pap smear was 56%. The culture media were equally efficient in identifying Trichomonas vaginalis. There were no differences found between subjects with or without trichomonas infections in gynecological symptoms, previous history of sexually transmitted diseases, or use of a condom at last intercourse. CONCLUSIONS: InPouch TV culture is a good diagnostic method for T. vaginalis because of its long shelf-life, relatively low expense, and high sensitivity (over twice as sensitive as wet-mount).

Adolescent↗
PubMed1998

Pulmonary embolism: diagnosis with spiral CT and ventilation-perfusion scanning--correlation with pulmonary angiographic results or clinical outcome.

PURPOSE: To compare the accuracy of spiral computed tomography (CT) with that of ventilation-perfusion (V-P) scintigraphy in the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: Fifty-four patients in whom indeterminate V-P scans or discordant clinical and scintigraphic results were obtained underwent both V-P scanning and contrast material-enhanced spiral CT. The reference standard was pulmonary angiographic results in 26 patients (group I) or clinical outcome in 28 (group II). RESULTS: Six (25%) of 24 group I patients had proved PE. The prospective sensitivity and specificity for segmental or subsegmental PE were 67% and 100%, respectively, and the positive and negative predictive values were 100% and 90%, respectively. In two group II patients, V-P scans had high probability for acute embolism, but spiral CT scans showed only chronic PE; in one patients, the V-P scan had low probability and the CT scan was positive for acute PE. An alternative CT diagnosis was established in four (31%) of 13 patients in whom a normal or low-probability V-P scan was obtained. Clinical outcome was consistent with spiral CT results in all cases. CONCLUSION: Spiral CT has greater accuracy and specificity than V-P scanning in patients with an unresolved diagnosis and may be useful as the primary screening technique for PE.

Acute Disease↗
PubMed1998

Accuracy of diagnosis of subtle chest disease and subtle fractures with a teleradiology system.

OBJECTIVE: This study compared conventional thoracic and skeletal radiographs with 12-bit digitized images of the same radiographs in terms of subjective image quality and accuracy of diagnosis of subtle disease. MATERIALS AND METHODS: Thirty-six chest radiographs with normal findings, 48 chest radiographs with abnormal findings, 29 skeletal radiographs with normal findings, and 26 skeletal radiographs with abnormal findings were included in this study. The images were chosen for the subtlety of their findings (nodules, pneumothoraces, interstitial lung disease, fractures). Each set of images was laser-digitized and viewed independently by three radiologists at a teleradiology workstation with a 1280 x 1024 pixel matrix monitor equipped with an eight-bit-per-pixel gray-scale display. All images were viewed at maximum resolution. After review of the digitized images for image quality and for the presence of abnormalities, each radiologist analyzed the analog images in a similar way. RESULTS: Sensitivities for detecting nodules, pneumothoraces, and interstitial lung disease on digitized chest radiographs were 58%, 75%, and 90%, respectively, compared with 62%, 79%, and 92%, respectively, on the original radiographs. Sensitivity for fracture detection on digitized bone radiographs was 87% compared with 88% on analog radiographs. None of these differences was statistically significant. CONCLUSION: Digitization of radiographs for primary diagnosis by teleradiology results in a slight decrease in sensitivity for detection of subtle abnormalities, provided that the images are viewed at maximum resolution.

Fractures, Bone↗
PubMed1997

Randomised double blind controlled study of recurrence of gastric ulcer after treatment for eradication of Helicobacter pylori infection.

OBJECTIVE: To determine whether eradication of Helicobacter pylori infection reduces recurrence of benign gastric ulceration. DESIGN: Randomised, double blind, controlled study. Patients were randomised in a 1:2 ratio to either omeprazole 40 mg once daily for eight weeks or the same treatment plus amoxycillin 750 mg twice daily for weeks 7 and 8. A 12 month untreated follow up ensued. SETTING: Teaching and district general hospitals between 1991 and 1994. SUBJECTS: 107 patients with benign gastric ulcer associated with H pylori. MAIN OUTCOME MEASURES: Endoscopically confirmed relapse with gastric ulcer (analysed with life table methods), H pylori eradication, and healing of gastric ulcers (Mantel-Haenszel test). RESULTS: 172 patients were enrolled. Malignancy was diagnosed in 19; 24 were not infected with H pylori; four withdrew because of adverse events; and 18 failed to attend for start of treatment, leaving 107 patients eligible for analysis (35 omeprazole alone; 72 omeprazole plus amoxycillin). In the omeprazole/amoxycillin group 93% (67/72; 95% confidence interval 84% to 98%) of gastric ulcers healed and 83% (29/35; 66% to 94%) in the omeprazole group (P = 0.103). Eradication of H pylori was 58% (42/72; 46% to 70%) and 6% (2/35; 1% to 19%) (P < 0.001) and relapse after treatment was 22% (16/72) and 49% (17/35) (life table analysis, P < 0.001), in the two groups, respectively. The recurrence rates were 7% (3/44) after successful H pylori eradication and 48% (30/63) in those who continued to be infected (P < 0.001). CONCLUSIONS: Eradication of H pylori reduces relapse with gastric ulcer over one year. Eradication rates achieved with this regimen, however, are too low for it to be recommended for routine use.

Amoxicillin↗
PubMed1997

Bleomycin-induced lung disease in an animal model: correlation between computed tomography-determined abnormalities and lung function.

RATIONALE AND OBJECTIVES: The authors evaluated whether specific types of computed tomographic (CT) abnormalities could be correlated with physiologic impairment in animals with bleomycin-induced lung injury. METHODS: Lung injury was induced in 20 rabbits by means of intratracheal administration of bleomycin (3 U per kilogram of body weight), followed by 100% oxygen for 2 minutes. The animals underwent high-resolution CT scanning at 14 (n = 4), 28 (n = 6), or 56 (n = 10) days after injury. CT morphometry was used to determine the extent of abnormal lung. Physiologic evaluation was performed before injury and before scanning. RESULTS: The overall extent of abnormal lung and of parenchymal opacification on CT scans did not correlate with any physiologic variable. The extent of interstitial thickening correlated significantly with total lung capacity (r = -.783, P = .0005), airway pressure at maximal lung volume (r = .836, P = .0001), and alveolar-arterial oxygen gradient (r = .613, P = .004). CONCLUSION: CT findings of interstitial thickening are associated with impaired gas exchange and lung stiffness in rabbits.

Animals↗
PubMed1997

Small intestine in lymphocytic and collagenous colitis: mucosal morphology, permeability, and secretory immunity to gliadin.

There is a recognised association between the "microscopic" forms of colitis and coeliac disease. There are a variety of subtle small intestinal changes in patients with "latent" gluten sensitivity, namely high intraepithelial lymphocyte (IEL) counts, abnormal mucosal permeability, and high levels of secretory IgA and IgM antibody to gliadin. These changes have hitherto not been investigated in microscopic colitis. Nine patients (four collagenous, five lymphocytic colitis) with normal villous architecture were studied. Small intestinal biopsies were obtained by Crosby capsule; small intestinal fluid was aspirated via the capsule. IEL counts were expressed per 100 epithelial cells, and intestinal IgA and IgM antigliadin antibody levels were measured by ELISA. Small intestinal permeability was measured by the lactulose:mannitol differential sugar permeability test. IEL counts were normal in all cases, median 17, range 7-30. Intestinal antigliadin antibodies were measured in six cases and were significantly elevated in two patients (both IgA and IgM). Intestinal permeability was measured in eight cases and was abnormal in two and borderline in one. These abnormalities did not overlap: four of nine patients had evidence of abnormal small intestinal function. Subclinical small intestinal disease is common in the two main forms of microscopic colitis.

Adult↗
PubMed1997

Observer variation and relationship of computed tomography to severity of beryllium disease.

Although high resolution computed tomography (HRCT) is commonly used to assess interstitial lung disease (ILD), relatively little is known about interrater reliability and construct validity of HRCT-reported nodules, ground-glass opacity, or other typical findings. We determined the interobserver and intraobserver variability of HRCT findings and correlated HRCT abnormalities with physiologic measures in 57 patients with chronic beryllium disease (CBD). Reliability of HRCT scan measurements were assessed using weighted kappa (K(W)) and intraclass correlation coefficients. We correlated HRCT with spirometry, body plethysmographic lung volumes, diffusing capacity for carbon monoxide (DL(CO)), maximal exercise testing with measurement of arterial blood gases, and bronchoalveolar lavage (BAL). Interobserver agreement for three of the HRCT abnormalities found in CBD was moderate: the K(W) for nodules, septal lines, and ground-glass attenuation were 0.53, 0.44, and 0.53, respectively. Agreement was poor for bronchial wall thickening (K(W) = 0.15). HRCT scores correlated significantly with DL(CO), gas exchange at rest and at maximal exercise, and lung volume. This study demonstrates that HRCT has good interrater reliability and correlates with indices of the severity of granulomatous lung diseases such as CBD.

Adult↗
PubMed1996

Serum and gastric luminal epidermal growth factor in Helicobacter pylori-associated gastritis and peptic ulcer disease.

BACKGROUND: Helicobacter pylori is the cause of chronic (type B) gastritis, duodenal ulceration (DU), and gastric ulceration (GU). Smoking is associated with delayed ulcer healing. Epidermal growth factor (EGF) is produced in the salivary and Brunner's glands of the upper gastrointestinal tract, inhibits gastric acid secretion, and is a powerful mitogen. MATERIALS AND METHODS: We sought to determine gastric luminal EGF (GL-EGF) in smokers and patients with Hp-associated DU and the effects of Hp eradication. Our aim was to determine GL-EGF in patients with GU and the effect of ulcer healing and to measure serum EGF in patients with Hp gastritis with or without DU disease. RESULTS: GL-EGF was reduced in smokers compared to controls (p = .008). Subjects with HP gastritis had reduced GL-EGF compared to controls (p = .0002). There was no difference in GL-EGF between Hp-positive subjects who had DU and those with chronic gastritis alone. Eradication of Hp from those patients with DU had no effect on the low levels of GL-EGF. There was no difference between GL-EGF in Hp gastritis alone and in Hp-associated active GU. GL-EGF fell after ulcer healing (p = .04), a difference confirmed by analysis of paired samples from patients before and after ulcer healing (p = .03). There was no difference in serum EGF between controls and subjects with Hp infection. There was no difference in serum EGF in subjects with DU associated and non-ulcer-associated gastritis. CONCLUSIONS: Subjects with Hp gastritis, or those who smoke, had low concentrations of GL-EGF regardless of whether DU was present. Eradication of Hp did not return the concentrations of GL-EGF to normal in DU subjects. Individuals and Hp gastritis and inactive GU had low levels of GL-EGF compared to non-ulcer Hp infection. The relative increase in GL-EGF that occurred with ulceration of the gastric mucosa may have resulted from the development of an ulcer-associated cell lineage. Serum EGF did not play a role in the pathogenesis of Hp gastritis or of associated DU ulcer disease.

Adult↗
PubMed1996

Ascorbic acid and total vitamin C concentrations in plasma, gastric juice, and gastrointestinal mucosa: effects of gastritis and oral supplementation.

Epidemiological evidence suggests that high dietary ascorbic acid reduces gastric cancer risk. It may do this by either reducing N-nitroso compound formation in gastric juice, or by scavenging reactive oxygen species in gastric mucosa. The aim of this study was to discover if potential ascorbic acid protection might be increased by supplementation. Thirty two patients were supplemented with ascorbic acid, 500 mg twice daily for two weeks. Gastric juice, plasma, and upper gastrointestinal biopsy ascorbate concentrations were measured and compared with values in 48 unsupplemented patients. It was found that ascorbic acid and total vitamin C concentrations were considerably higher in biopsy specimens from oesophagus, body, antrum, duodenum, and rectum, compared with values in plasma or gastric juice. Plasma and mucosal concentrations were unaffected by the presence of chronic gastritis but gastric juice concentrations were substantially lower in patients with chronic gastritis than in patients with normal histological assessment (p < 0.01). Patients receiving ascorbic acid supplements had higher ascorbic acid concentrations in plasma (p < 0.001), gastric juice (p < 0.001), and at all biopsy sites in the upper gastrointestinal tract (p < 0.05). Gastric juice ascorbic acid and total vitamin C concentrations in gastritic patients, however, were still less after supplementation than in normal subjects (p < 0.01). These data suggest that high ascorbic acid intake could reduce gastric cancer risk, but its protective effect might be greater if gastritis is treated (for example, by Helicobacter pylori eradication).

Adult↗
PubMed1996

Lung transplantation: indications, donor and recipient selection, and imaging of complications.

Lung transplantation has become a well-established treatment for end-stage pulmonary parenchymal and vascular disease. Careful selection of recipients and donors is important to decrease early graft failure, which is primarily due to rejection and bronchial dehiscence. Common complications include the reimplantation response, acute rejection, pleural effusion, lymphoproliferative disorders, bronchiolitis obliterans, infection, and airway stenosis or dehiscence. The reimplantation response is a form of noncardiogenic pulmonary edema that begins soon after surgery and resolves in days to weeks. Acute rejection occurs in most recipients; a dramatic response to steroid therapy is the most diagnostic clinical feature. Lymphoproliferative disorders are posttransplantation neoplasms that may disappear when immunosuppressive therapy is stopped and often manifest as a discrete lung mass. In bronchiolitis obliterans-a major long-term complication probably due to chronic rejection-computed tomography (CT) often shows bronchial dilatation and air trapping. Airway stenosis and dehiscence are easily diagnosed with bronchoscopy and CT. Infections remain the major cause of morbidity and mortality.

Adult↗
PubMed1996

Diffuse panbronchiolitis in the United States.

Diffuse panbronchiolitis (DPB), an important cause of progressive obstructive lung disease in the Far East, represents a distinctive sinobronchial syndrome with typical radiologic and histologic features. We have identified DPB in five citizens of the United States, three with histologic confirmation, who have never traveled to the Far East. There were four men and one woman, whose ages ranged from 46 to 75 yr at the time of diagnosis. All had a prior history of chronic sinusitis and presented with cough, dyspnea, and sputum production. Three were never smokers and two were current smokers. Pulmonary function testing revealed severe airflow limitation (the FEV1 ranging from 22% to 56% of predicted), and overdistention. All patients had high-resolution computed tomographic (HRCT) scans indicating centrilobular nodules with adjoining thickened and dilated bronchioles. In the three patients in whom open lung biopsy was performed, there was bronchiolocentric infiltration of lymphocytes, plasma cells, and foamy macrophages. Three patients remain alive and are being treated with chronic macrolide therapy. The clinical, radiographic, and histologic features of these patients closely resemble those described in Japanese patients. DPB must be considered in the differential diagnosis of sinopulmonary syndromes, bronchiolitis, and cryptic cases of obstructive lung disease among United States citizens, since therapy now offers an improved prognosis.

Aged↗
PubMed1996

Quantitative CT predicts the severity of physiologic dysfunction in patients with lymphangioleiomyomatosis.

PURPOSE: To assess quantitative high-resolution CT (quantitative CT) as a diagnostic and prognostic tool in pulmonary lymphangioleiomyomatosis. METHODS: Spirometry, lung volumes, diffusing capacity, exercise physiology, and expiratory high-resolution CT (HRCT) examinations were performed on a cohort of ten patients with the diagnosis of lymphangioleiomyomatosis (LAM) referred to a tertiary care center. HRCT examinations were also done on ten normal control subjects. A thresholding technique was used to quantitatively assess the amount of abnormal cystic parenchyma present on each of the two images obtained for each subject with LAM and for each normal control subject. This numeric index of cystic parenchyma, the quantitative CT index, was then examined (1) as a diagnostic measure to distinguish the subjects with LAM from the normal control subjects and (2) as a prognostic measure to assess disease severity in the subjects with LAM. Linear regression of the quantitative CT index against physiologic indexes of pulmonary function and exercise performance was analyzed to determine the relationship between this radiologic assessment of disease severity and functional impairment. RESULTS: The quantitative CT index was significantly greater for the LAM patients, 37.2 +/- 6.9 (SEM), compared with the control group, 0.8 +/- 0.2 (p = 0.0001). Linear regression analysis demonstrated significant linear correlation between the quantitative CT index and measures of airflow (FEV1, r = -0.90, p = 0.0005), air trapping (residual volume, r = 0.70, p = 0.02), diffusing capacity (diffusing capacity for carbon monoxide, r = -0.76, p = 0.01), gas exchange (alveolar to arterial oxygen gradient) at rest, r = 0.69, p = 0.007, and at maximum exercise, r = 0.79, p = 0.007) and exercise performance (maximum workload, r = -0.84, p = 0.002), and oxygen utilization (oxygen utilization at maximum exercise, r = -0.76, p = 0.01). CONCLUSION: Quantitative CT techniques can distinguish subjects with LAM from normal controls. Further, the quantitative CT index correlates well with physiologic measurements of airflow, lung volumes, diffusing capacity, and exercise performance and, thus, may provide a useful measure of disease severity.

Adult↗
PubMed1995

Automated discrimination and quantification of idiopathic pulmonary fibrosis from normal lung parenchyma using generalized fractal dimensions in high-resolution computed tomography images.

RATIONALE AND OBJECTIVES: We computed generalized fractal dimensions for high-resolution computed tomography (HRCT) images to investigate their value in the discrimination and quantification of idiopathic pulmonary fibrosis (IPF) from normal lung parenchyma. METHODS: A probability distribution that was based on the pixel value in each image was used to compute capacity, information, and higher fractal dimensions for a series of 52 HRCT slices obtained from four patients. Qualitative classification of normal, mild, moderate, and severe IPF cases was achieved by computing the following parameter: DD = D0 - 2D1 + D2, where D0, D1, and D2 represents the capacity, information, and pair correlation dimensions, respectively. A multiple linear regression analysis using morphometric quantification for the set of 52 slices was tested for all possible combinations of the parameters D0, D1, D2, and D3. The generalizability of the model was tested by predicting the extent of IPF for each patient from a regression model computed with the remaining slices in the database. RESULTS: The best regression results were obtained using the independent parameters D1 and D2 to quantify the extent of diseased lung parenchyma. The technique was tested with 48 slices from 12 new patients. The results indicated that the extent of IPF could be predicted within the confidence limits given by the regression analysis. CONCLUSION: The extent of IPF can be predicted well within the 90% confidence interval given by the model. The width of the confidence interval decreases as the number of slices used in the linear regression model increases. This operator-independent quantitative technique may be useful in the follow-up of patients with IPF.

Confidence Intervals↗