Biomedical subjects
Publications and source records attributed to G D Dunn.
The development of a pneumothorax is a recognized complication of ultrasound-guided percutaneous liver biopsy. A way of detecting such a complication using real-time ultrasound is described, whereby the well-visualized liver disappears from the monitor screen. We also discuss the reasons for this occurrence.
A case of small bowel volvulus in an adult is presented. The established CT signs of small bowel volvulus are discussed. These include an abnormal orientation of the superior mesenteric artery to the superior mesenteric vein; the whirl sign, the triangle sign and the beak sign.
PURPOSE: To evaluate the role of computed tomography in patients with dacryostenosis. METHODS: One hundred seven cases of dacryostenosis (94 patients) were assessed by thorough clinical and lacrimal history and examination, and lacrimal region computerized tomography (CT). The lacrimal drainage system examination included the state and position of the puncta; Jones testing; lacrimal syringing; and, in the latter half of the study, telescopic nasal endoscopy. The patients were drawn from the hospital outpatients and private office of the operating lacrimal surgeon in this series (I.C.F.). Of the 107 cases, 79 either underwent dacryocystorhinostomy surgery or had this planned. RESULTS: In 14 of the 107 cases (12 patients), preoperative CT led to an alteration of patient management, usually referral to an otolaryngologist for further evaluation or treatment. In addition to the detection of two tumors extrinsic to the sac, conditions such as ethmoiditis, lacrimal sac mucoceles, soft tissue opacity in the nasolacrimal duct, gross nasal polyposis, fungal sinusitis, and a dacryolith were observed by CT. CONCLUSION: Similar to the role of functional endoscopic sinus surgery in otolaryngology, CT imaging will become increasingly important in the assessment of many patients with symptoms of lacrimal drainage obstruction.
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The presence of a fatty liver often complicates the interpretation of abdominal computed tomography (CT). Abnormalities in or adjacent to the liver, including dilated bile ducts, liver masses and subphrenic collections, may be masked by the fatty liver. Furthermore, normal structures may simulate pathological conditions. Five cases are presented to illustrate some of these diagnostic pitfalls.
Adhesion of circulating tumor cells to microvascular endothelium plays an important role in tumor metastasis to distant organs. The purpose of this study was to determine whether nitric oxide (NO) would attenuate tumor cell adhesion (TCA) to naive or lipopolysaccharide (LPS)-treated postcapillary venules. A melanoma cell line, RPMI 1846, was shown to be much more adhesive to postcapillary venules isolated from rat mesentery than to corresponding precapillary arterioles. Although venules exposed to LPS for 4 h demonstrated an increased adhesivity for the melanoma cells, TCA to LPS-treated arterioles was not altered. Isolated venules exposed to DETA/NO (1 mM), an NO donor, for 30 min prior to tumor cell perfusion prevented the increment in adhesion induced by LPS and attenuated TCA to naive postcapillary venules. While L-arginine (100 microM), an NO precursor, failed to decrease TCA to naive postcapillary venules, this treatment abolished LPS-stimulated TCA to postcapillary venules. The effect of L-arginine was reversed by administration of N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 microM), an NO synthase (NOS) inhibitor. These observations indicate that both exogenous and endogenous NO modulate TCA to postcapillary venules. To assess the role of NO-induced activation of cGMP in the reduction in TCA produced by DETA/NO, two additional series of experiments were conducted. In the first series, LY-83583 (10 microM), a guanylyl cyclase inhibitor, was shown to completely reverse the effect of DETA/NO on TCA to both naive and LPS-activated postcapillary venules. On the other hand, administration of 8-bromoguanosine 3',5'-cyclic monophosphate (8-B-cGMP) (1 mM), a cell permeant cGMP analog, mimicked the effect of DETA/NO and reduced TCA to LPS-stimulated postcapillary venules. These data suggest that (a) tumor cells are more likely to adhere to postcapillary venules than to corresponding precapillary arterioles, (b) LPS enhances TCA to postcapillary venules, (c) both exogenously applied (DETA/NO) and endogenously generated (L-arginine) NO attenuate the enhanced adhesion induced by LPS, but only DETA/NO reduced TCA to naive postcapillary venules, and (d) the NO-induced reduction in TCA to LPS-activated postcapillary venules occurs by a cGMP-dependent mechanism.
Mucosal and systemic immunologic recognition of cagA by Helicobacter pylori-infected individuals is associated with peptic ulcer disease; however, in the laboratory, expression of cagA is subject to artificial conditions which may not accurately reflect the conditions in host tissues. Gastric antral and body biopsy specimens and serum for anti-H. pylori immunoglobulin G serology were obtained from 42 patients. Biopsy specimens were studied by histology, culture, and reverse transcription PCR (RT-PCR). Oligonucleotide primers specific for H. pylori (16S rRNA, ureA, and cagA) were used to detect bacterial mRNA in gastric biopsy specimens. PCR was performed on DNA from corresponding H. pylori isolates to detect genomic 16S rRNA, ureA, and cagA. Of the 42 patients from whom clinical specimens were obtained, 25 were infected with H. pylori on the basis of both serology and histology or culture (i.e., tissue positive); 13 were negative by serology, histology, and culture; and 4 were positive by serology only. RT-PCR with 16S rRNA primers detected 24 of 25 tissue-positive and 0 of 17 tissue-negative patients (P < 0.001). RT-PCR with ureA primers detected 16 of 25 tissue-positive and 0 of 17 tissue-negative patients (P < 0.001). CagA mRNA was detected by RT-PCR in 14 of 25 gastric biopsy specimens in the tissue-positive group and in 0 of 17 gastric biopsy specimens in the tissue-negative group. PCR of genomic DNA for the presence of the cagA gene in the corresponding bacterial isolates correlated absolutely with cagA gene expression in gastric tissue. These results indicate that RT-PCR is a sensitive and specific method for the detection of the presence of H. pylori and the expression of H. pylori genes in human gastric tissue. Detection of H. pylori gene expression in vivo by this approach may contribute to improving the diagnosis and understanding the pathogenesis of H. pylori infections.
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To assess our clinical experience with this method of enteral feeding, we conducted a retrospective study and follow-up of 73 patients having percutaneous endoscopic gastrostomy (PEG). In addition, we conducted a telephone survey of 42 persons who cared for the PEG tube. The most common indication was neurologic impairment of deglutition. Early and late complications occurred in 12% and 33% of cases, respectively, and were usually minor. Our 30-day survival was 74%. Most patients (77%) maintained their weight with standard tube feedings. Satisfaction with and acceptance of the PEG was almost universal. Patients should be carefully selected, with attention to long-range benefit.
The results of ultrasound imaging combined with Doppler studies of blood flow are presented in two patients with surgical portacaval shunts performed for portal hypertension. Duplex scanning proved a quick and noninvasive method of confirming the patency of the anastomoses. The demonstration of appropriate Doppler flow signals across the shunt is the most convincing ultrasound evidence of patency. Portacaval shunts are more amenable to study by ultrasound than more peripheral shunts because the liver can be used as an acoustic window.
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In three patients with phaeochromocytomas, computed tomography or iodobenzylguanidine scanning gave misleading or negative results. These patients were found to have a functioning middle mediastinal paraganglioma in association with one or two intercarotid paragangliomas. The possibility of this association should be considered in patients with functioning extra-adrenal paragangliomas.
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Eight children (aged 8 mo to 13 yr) with cystic fibrosis (CF) and growth failure were given home nocturnal nasogastric feeding of an elemental diet for 3 mo and re-evaluated 3 mo after cessation of tube feeding. An increase in energy intake (p less than 0.05) resulted in increased serum transferrin (p less than 0.005), retinol-binding protein (p less than 0.05), and clinical scores (p less than 0.05) during the study. Height and growth velocity increased by 60% (p less than 0.05), and weight growth velocity increased by 63%. Arm-muscle circumference, triceps skinfolds, serum albumin, vitamin A, vitamin E, zinc, and copper did not change significantly during tube feeding. Nocturnal feeding were safe and effective in promoting growth; however, most children with severe lung disease did not sustain the gains after cessation of tube feeding. Our findings indicate that continued nutritional support is needed to maintain the growth in malnourished children with severe lung disease.
We have reported a case of occult, diffuse gastric cancer in a young adult with progressive shortness of breath and bilateral pulmonary interstitial infiltrates. Progressive shortness of breath may be the first or only manifestation of occult gastric cancer caused by either lymphangitic carcinomatosis or microscopic tumor emboli to the lungs. Widespread recognition of this syndrome, a high index of suspicion, and prompt lung biopsy are necessary to make the correct diagnosis. With progress in chemotherapy for malignant diseases, early diagnosis and specific treatment may improve the prognosis of this condition.
Ultrasonography (US) performed in nine patients (two with pancreatic carcinoma, one with hepatomegaly, six with no relevant abdominal disease) showed the pancreas to lie wholly to the left of the aorta. This not uncommon location may give rise to difficulty in demonstrating the pancreas on real-time US scans. The superior mesenteric vessels and splenic vein remain useful landmarks for locating the head of the pancreas in this position.