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Biomedical subjects

R H Riddell

Publications and source records attributed to R H Riddell.

At least 73 records · Page 4Linked to original sources
PubMed1990

14C-urea breath test for the detection of Helicobacter pylori.

The high urease activity of Helicobacter pylori can be used to detect this bacterium by noninvasive breath tests. We have developed a 14C-urea breath test which uses 5 microCi 14C with 50 mg nonradioactive urea. Breath samples are collected at baseline and every 30 min for 2 h. Our study compared the outcome of the breath test to the results of histology and culture of endoscopically obtained gastric biopsies in 84 patients. The breath test discriminated well between the 50 positive patients and the 34 patients negative for Helicobacter pylori: the calculated sensitivity was 100%, specificity 88%, positive predictive value 93%, and negative predictive value 100%. Treatment with bismuth subsalicylate and/or ampicillin resulted in lower counts of exhaled 14CO2 which correlated with histological improvement in gastritis. The 14C-urea breath test is a better "gold standard" for the detection of Helicobacter pylori than histology and/or culture.

Biopsy↗
PubMed1990

Management of colonic dysplasia and adenomas.

The major problems with the management of dysplasia in the large bowel are few when dealing with adenomas or invasive carcinomas. Many more problems arise in the clinical and pathologic management of dysplasia in inflammatory bowel disease. The interesting question of dysplasia occurring in other polyps remains intriguing, and particularly the notion that hyperplastic and adenomatous polpys tend to occur in the same segment of bowel and therefore may have the same predisposing factor. We hope that by the time the next volume of the monograph is published on gastrointestinal pathology, all of these problems will have been resolved.

Adenoma↗
PubMed1989

Mast cells are closely apposed to nerves in the human gastrointestinal mucosa.

Mast cell/nerve associations have been recorded in several publications; however, the human gastrointestinal tract has received little attention. Accordingly, mucosal samples from small bowel, appendix, and large bowel were studied. Combined histochemical/immunocytochemical techniques revealed that the proportion of mast cells apposed to nerves ranged from 47.08% +/- 6.10% to 77.66% +/- 4.26%. The highest incidence of contact was observed in the appendix; where the apparent nerve density was also greater than in the large or small bowel. Electron-microscopic studies revealed many mast cells adjacent to nerve fibers and membrane-to-membrane contact between axonlike processes and mast cells. Often, these processes were dilated, as were axons in adjacent nerve fibers. These data provide a microanatomic basis for potential communication between nerves and mast cells in the human gastrointestinal mucosa. This may be of physiologic significance in the normal individual and important in disease processes, such as inflammation and fibrosis.

Adult↗
PubMed1989

Bone core biopsies. Plastic or paraffin?

Plastic embedding of bone core biopsy specimens has been promoted as providing superior morphology, primarily because semi-thin sections can thereby be cut at 1-2 mu. The major disadvantages of plastic embedding are that it increases the technical load, is more expensive, and potentially has its own intrinsic problems, including difficulties in performing special stains and immunoperoxidase studies. In order to investigate the possibility that semi-thin paraffin sections may provide similar morphological results without the intrinsic disadvantages of plastic sections, we examined 45 bone core biopsy specimens that were sufficiently large to process one half in plastic and the other half in paraffin following decalcification. Both were cut at 1-2 mu. Although many plastic sections appear esthetically more pleasing, semi-thin paraffin sections of very high quality can also be obtained routinely. Additional advantages of paraffin sections were the ability to perform peroxidase studies, lower cost, less technologist time, and avoidance of problems occasionally arising with plastic, such as difficulties with impregnation or problems with polymerization. Peroxidase studies were particularly useful in patients with possible myeloma that was not overt on hematoxylin-and-eosin section and in confirming the presence or source of metastatic carcinoma. We therefore recommend the use of semi-thin (1-2 mu) paraffin sections for routine examination of bone core biopsy specimens.

Biopsy↗
PubMed1989

Mucosal cysts in Barrett's mucosa with dysplasia.

The frequency of glandular cysts occurring in the Barrett's mucosa was investigated in areas adjacent to invasive adenocarcinoma in 32 resected esophagi. Cysts in the metaplastic glands of the Barrett mucosa were present in areas with and without dysplasia in 31 of the 32 specimens. The mean cyst index (i.e. the number of glandular cysts divided by the length-in mm-of mucosa analyzed) was 2.3 in the non-dysplastic Barrett mucosa, and 2.5 in the Barrett mucosa with dysplasia. Significantly lower indices (p less than 0.001) were found in areas with metaplastic glands covered by "healing" squamous epithelium (0.47) and in the gastric mucosa of the same patients (0.15) as well as in 10 control esophagi underneath normal squamous epithelium (0.11). The outlet of the dilated glands was often obstructed by clusters of dysplastic cells or papillary formations with atypical cells, substantiating on obstructive-causal mechanism in these cysts. Other cysts were partially or totally replaced by dysplastic epithelium. The present findings may be of importance for the histological differential diagnosis between dysplasia and highly differentiated adenocarcinomas in biopsy specimens from the Barrett Mucosa.

Adenocarcinoma↗
PubMed1989

Optimization of a medium for the rapid urease test for detection of Campylobacter pylori in gastric antral biopsies.

We developed a buffered azide-free urea medium which is sensitive, specific, and nontoxic for rapid detection of Campylobacter pylori in gastric biopsies. Detection of urease produced by the organism provides the basis for the test. The substrate is urea in monobasic sodium phosphate buffer, and phenol red provides indication of the pH change that results from urease activity. A rapid change from yellow to red occurs in the presence of C. pylori, even at low concentrations of the organism. A slower color change occurs with higher concentrations of other urease producers, such as Yersinia enterocolitica and Proteus mirabilis. Experience with 51 patients with our medium showed excellent results in detection of C. pylori in gastric mucosal biopsies. In clinical research and practice, a rapid bedside test will be helpful for rapid diagnosis of C. pylori-positive patients.

Azides↗
PubMed1988

Changes in rat and human pepsinogen phenotypes induced by N'-methyl-N'nitro-N-nitrosoguanidine.

Changes have been studied in human and rat pepsinogen phenotypes induced by N'-methyl-N'nitro-N-nitrosoguanidine (MMNG) in in vitro rat experiments and in vivo cultures of human and rat isolated gastric chief cells. In vivo the fastest migrating electrophoretic band decreased or disappeared as early as 3 weeks after the start of MNNG treatment. The changes, observed in 17 of 32 rats receiving MNNG, were permanent and consistently associated with pronounced histopathologic changes seen 10 months later (17 of 17). Comparable phenotypic changes were observed after 7 days only in MNNG-treated rat chief cell cultures. In human chief cell cultures a decrease of the Pg3 band, which is consistent with the "carcinogenic" phenotype, was observed in two of six preparations treated with MNNG. This early preceding change in phenotype preceding tumor formation may be useful as a diagnostic tool for the onset of gastric cancer.

Animals↗
PubMed1988

Colorectal polyps: a correlation of radiological and pathological findings.

Ninety colorectal polyps seen on double contrast barium enema were reviewed and note was made of surface and base characteristics, size, site and the presence of associated disease. Results were then correlated with the histology. The radiological characteristics of each histological type of polyp encountered are described. Because of the variation in radiological appearance of each histological type and similarities in appearance between these types, we conclude that radiology cannot accurately predict the histology of a colorectal polyp.

Adult↗
PubMed1988

An immunohistochemical study of pleomorphic adenomas of the salivary gland: glial fibrillary acidic protein-like immunoreactivity identifies a major myoepithelial component.

An immunohistochemical study of 34 pleomorphic adenomas of the major salivary glands demonstrated phenotypic differences among the various morphologic regions in these tumors. The phenotypes expressed were comparable to those of normal salivary gland cells. In the normal glands, myoepithelial cells were immunoreactive for glial fibrillary acidic protein (GFAP), S-100 protein, and keratin; acinic cells exhibited strong, predominantly nuclear S-100 staining and weaker keratin staining; intercalated ducts had both cytoplasmic and nuclear S-100 positivity; and several epithelial antigens were observed throughout the ductal system. In the tumors, the presence of classic epithelial markers (including carcinoembryonic antigen, epithelial membrane antigen, secretory component, and keratin) in the luminal cells of ducts and the intense immunoreactivity with GFAP (with weaker keratin and S-100 staining) in periductal and stromal cells indicated distinct epithelial and myoepithelial differentiation. Solid epithelioid areas consisted phenotypically of intercalated duct/acinic cells and/or myoepithelial cells, the former exhibiting predominant nuclear S-100 positivity. The presence of GFAP-like immunoreactivity in normal myoepithelial cells strongly supports the extensive involvement of this cell in pleomorphic adenomas. The spectrum of phenotypes expressed adds weight to existing evidence for pleomorphism rather than a mixed origin of this tumor. The combination of keratin, S-100, and GFAP immunostaining is particularly useful in identifying the component cells in pleomorphic adenomas of the salivary glands.

Adenoma↗
PubMed1988

Atypical mitoses in dysplasias of the Barrett's mucosa.

The frequency of mitotic figures, the proportion of atypical mitoses, and the spatial position (vertical or horizontal) of metaphasal plates were studied in resected specimens from 18 patients having Barrett's mucosa with dysplasia, and/or invasive adenocarcinoma. The number of dividing glandular cells increased (by comparison with the non-dysplastic Barrett's mucosa) in areas with dysplasia and with invasive adenocarcinoma, the largest percentage was found in the latter. Atypical mitoses were often found in areas with glandular dysplasia and with invasive adenocarcinoma. The highest frequency was found in adenocarcinoma. While 90.8% of the metaphases in Barrett's mucosa without dysplasia had a vertical position, only 39.5% of the mitoses in areas with dysplasia had the same position. It is conceivable, that the number of mitoses, the number of atypical mitoses as well as the spatial position of mitosis should be registered in the Barrett's mucosa with dysplasia in attempts to learn more about the biological behaviour of these lesions.

Adenocarcinoma↗
PubMed1988

The diagnosis of acute fatty liver of pregnancy by computed tomography.

We describe 2 patients with biopsy-proven acute fatty liver of pregnancy in whom the diagnosis was suggested by the finding of uniform reduced attenuation values on computed tomography (CT) of the liver. The attenuation values returned to normal with resolution of signs and symptoms following delivery. CT of the liver provides a useful method for the diagnosis of acute fatty liver of pregnancy.

Acute Disease↗
PubMed1988

Squamous mucosa overlying columnar epithelium in Barrett's esophagus in the absence of anti-reflux surgery.

Seven of 45 patients with Barrett's esophagus prospectively followed with yearly endoscopy had histological evidence of squamous mucosa overlying Barrett's epithelium. This histological finding has previously been identified as a rare sequela of anti-reflux surgery. All seven patients had specialized columnar epithelium. No evidence of the overlying mucosa was recognized at endoscopy. Only one patient had previous anti-reflux surgery. During the observation interval, three patients had a decrease, and four had no change in the length of Barrett's epithelium. Squamous mucosa overlying columnar epithelium in Barrett's esophagus is not infrequent, and prior anti-reflux surgery is not a necessary precondition.

Aged↗
PubMed1987

Composition of the refluxed material determines the degree of reflux esophagitis in the dog.

To evaluate the influence of the composition of refluxed material in the pathogenesis of esophagitis, a dog model was used to allow esophageal reflux of gastric secretions, duodenal pancreaticobiliary secretions, and a combination of both. Control dogs had only an esophageal incision. Incompetence of the cardia was established in five other groups by transecting the distal sphincter and creating a hiatal hernia. Two groups received moderate or maximal histamine stimulation of gastric secretion. A gastrojejunostomy, pyloromyotomy, and duodenal closure distal to the papilla were added in the other three groups, creating duodenogastric reflux; two were stimulated with histamine and one had a truncal vagotomy and no histamine. Radiologic, manometric, and pH studies showed that incompetence of the cardia was obtained. The dogs were killed 4 wk postoperatively and evaluated for gross and microscopic evidence of esophagitis. Erosive esophagitis was found only in dogs with reflux of gastric juice following maximal acid stimulation. Microscopic reflux changes in esophageal mucosa were seen in all groups; again, changes were most pronounced in dogs with maximal gastric stimulation. The combination of duodenogastric reflux and moderate gastric stimulation produced more significant alterations in microscopic reflux criteria than did moderate gastric stimulation alone. Our conclusions are as follows: In a dog model of gastroesophageal reflux of various combinations of gastric and duodenal secretory components, erosive esophagitis occurred only with maximal gastric stimulation in the absence of duodenogastric reflux. All reflux combinations, however, produced some degree of microscopic changes, suggesting they could eventually cause gross changes with a lengthened experimental time span.

Animals↗
PubMed1987

Hepatitis in patients receiving intraarterial chemotherapy for metastatic colorectal carcinoma.

Fifty-one patients with metastatic colorectal carcinoma confined to the liver received intraarterial chemotherapy through the hepatic artery via a subcutaneous pump. The chemotherapy consisted of sequential 14-day infusions of floxuridine (FUDR) and dichloromethotrexate (DCMTX) or a 14-day infusion of FUDR and bolus mitomycin (MMC). Twenty-four patients (47%) developed hepatitis with an elevation of hepatic serum transaminase (serum glutamic oxaloacetic transaminase, SGOT, or serum glutamic-pyruvic transaminase, SGPT). The median time to develop hepatitis was 11 weeks after initiation of chemotherapy. The morphologic effects of chemotherapy were evaluated in eight patients with hepatitis. All the patients with hepatitis had normalization of the serum transaminases after temporary cessation of chemotherapy. There was a trend toward a greater chance of remission in patients who developed hepatitis. Sixty-seven percent of the patients with a therapeutic response had hepatitis, whereas only 33% of the patients without a response had hepatitis. However, this difference was not statistically significant. The occurrence of hepatitis was not related to FUDR dose, drug program (FUDR-DCMTX vs. FUDR-MMC), pump flow rate, hepatic arterial anatomy, sex, or age of the patients.

Bilirubin↗