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Biomedical subjects

C M Allen

Publications and source records attributed to C M Allen.

At least 37 records · Page 2Linked to original sources
PubMed1998

Caliber-persistent labial artery. A common vascular anomaly.

Sixteen cases of caliber-persistent labial artery of the lips have been reported to date in the English literature. Six of these were clinically misdiagnosed as squamous cell carcinoma and treated with wedge resection. To date, we have seen 187 cases clinically and an additional 23 cases through our surgical oral pathology services. Careful clinical observation usually reveals a soft linear or papular bluish elevation above the labial mucosal surface. The unique feature is pulsation--not simply pulsation toward and away from the observer, which can be caused by an underlying artery, but lateral pulsation, which only an artery can exhibit. All but 2 of our 187 clinical cases were asymptomatic. To the best of our knowledge, this is the first report of caliber-persistent labial artery of the upper lip. The upper:lower lip ratio for the clinical cases was almost 2:1. Three times as many lower lip as upper lip lesions were biopsied. Males and females were almost equally affected (clinical cases, 76:86; histopathologic cases, 9:13). Although a vascular term (artery, hemangioma, phlebolith, varix, vascular malformation) was used on the biopsy form in one half of the clinical differential diagnoses, none of the clinical histories mentioned pulsation. In contrast to the cases of Miko et al. in 1980 and 1983, none of our cases manifested itself as an ulcer, nor was carcinoma ever mentioned in the clinical differential diagnosis. The purpose of this article is to familiarize clinicians and pathologists with the clinical and histopathologic features of this seldom reported but common vascular anomaly. Clinicians should carefully look for lateral pulsation in lip mucosal papules so as to avoid unnecessary surgery and intraoperative arterial bleeding. Pathologists should recognize that a relatively large-caliber superficial artery in a lip biopsy may not be an incidental finding but rather the clinical lesion that was biopsied.

Adult↗
PubMed1998

Adenomatoid dentinoma. Report of four cases of an unusual odontogenic lesion.

Four cases of a rare odontogenic lesion are reported. In each of the 4 examples, the lesion manifested itself as a well-circumscribed unilocular radiolucency in the mandibular third molar region in an adult. The histopathologic features consisted of an encapsulated proliferation of odontogenic hard and soft tissues. The hard tissue component consisted of dentin deposited in a peripheral ringlike configuration that enclosed odontogenic epithelium resembling adenomatoid odontogenic tumor. Whether this process represents a neoplasm or an odontogenic hamartoma is an unresolved question. Treatment in each case consisted of curettage, and no recurrences were observed.

Adult↗
PubMed1997

Macrognathia of renal osteodystrophy in dialysis patients.

A multiinstitutional study of macrognathia secondary to renal osteodystrophy in dialysis patients is presented. The nine cases reviewed reveal a variety of radiographic and histopathologic features, some of which resemble fibrous dysplasia and others suggestive of Paget's disease of bone. This article contains diagnostic criteria for differentiating renal osteodystrophy from similar fibro-osseous proliferations along with a discussion of the underlying cause and appropriate therapeutic interventions.

Adult↗
PubMed1996

New stimulation ligand of the adenovirus 2 protease.

The catalytic activity of the adenovirus cysteine peptidase is increased by a specific 11-amino-acid peptide adduct (GVQSLKRRRCF, referred to as pVIc). To identify additional peptides which might bind and alter the activity of the protease, a cysteine-constrained random peptide phage library was screened. Of 29 different phages which were isolated, 7 contained the consensus sequence VEGGS. Despite a superficial similarity to the substrate cleavage site of the protease, the peptide was not digested by the enzyme. VEGGS and pVIc altered protease activity similarly without sharing sequence similarity. To similar degrees, pVIc and VEGGS (a) stimulated the activity of the recombinant protease, (b) had no effect on viral protease, (c) increased the fluorescence emission of tryptophan residues in the protease, suggesting a conformational change, and (d) inhibited wt virus infection, but rescued ts1 infection at the nonpermissive temperature. The experiments also suggest that once the protease has been stimulated by one peptide, the other peptide has no further activity on the recombinant adenovirus cysteine protease, suggesting that the two peptides bring about the same change on the protease via different binding sites.

Adenoviruses, Human↗
PubMed1996

Activation of Fyn tyrosine kinase upon secretagogue stimulation of bovine chromaffin cells.

Adrenal medullary chromaffin cells derive from the neural crest during embryogenesis and differentiate into dedicated secretory cells that release catecholamines in response to acetylcholine in vivo or nicotinic agonists in vitro. Previous studies have indicated that tyrosine kinases participate in early secretagogue-induced events in these cells and are required for exocytosis. Abundant levels of the cytoplasmic tyrosine kinases, c-Src and c-Yes, have been detected in chromaffin cells, thereby implicating them as kinases relevant to these events. However, c-Src has been found to undergo a decrease in activity following secretagogue-stimulation, and c-Yes appears to exist in a constituitively low activity state, suggesting that other tyrosine kinases are involved. Furthermore, other members of the Src family of tyrosine kinases have been implicated as playing roles in secretion in a variety of cell types. Therefore, we sought to determine if other Src family members were present in chromaffin cells, and if so, to examine them for subcellular localization and changes in activity following treatment with nicotinic agonists. To this end, antibodies for Fyn, Lck, Lyn, and Fgr were assembled and used in immunoprecipitation, in vitro autokinase, and Western immunoblotting assays. Of these four kinases, only Fyn was found to be expressed at detectable levels. Differential centrifugation studies revealed that Fyn resides predominantly (> 95%) in the crude plasma membrane fraction and undergoes nicotinic-and carbachol-induced activation. This activation is reduced by the nicotinic antagonist, mecamylamine, is not elicited by muscarine, and is dependent upon the presence of extracellular Ca2+. These results suggest that Fyn is involved in signalling through the nicotinic receptor and may be one of the relevant kinases responsible for at least some of the tyrosine phosphorylations detected after stimulation.

Acetylcholine↗
PubMed1996

Portable chest radiology in intensive care: a comparison of a new dual characteristic film-screen system (Insight) incorporating a flexible grid with a standard film-screen system.

Insight (Insight, Kodak, UK) is a new dual image receptor system which utilizes an asymmetric film screen combination. Conventional radiography was compared with the Insight system, in combination with a cassette incorporating a flexible grid, in fifty patients on the intensive care unit. Radiographs were analysed by intensive care junior medical staff, nursing staff and two groups of radiologists. Insight provided better visualization of lung parenchyma, mediastinal detail and position of endotracheal tubes than conventional radiography. Central venous catheters were generally seen better on conventional radiographs than on Insight. Insight system produces a significant improvement in plain chest radiography in the intensive care unit. In the absence of digital radiography it is a suitable technique for routine radiography in the intensive care unit.

Aged↗