Search PubMed⌕ Search

Biomedical subjects

D M Casey

Publications and source records attributed to D M Casey.

At least 19 recordsLinked to original sources
PubMed1999

Dental blood supply in the segmentally resected mandible.

There are approximately 30,000 new cases of oral and pharyngeal carcinoma treated in the United States each year. A large number of these patients go on to receive segmental resection of the mandible, and have natural teeth remaining on the surgical side. To the best of our knowledge, there has not been a thorough discussion of the blood supply to these remaining teeth. Radiographic evidence of periapical pathology in these teeth is unusual, despite the compromised vascular supply. The purpose of this article is to report a case and review the literature on blood supply to teeth after segmental mandibulectomy. Microscopic examination was conducted on the pulpal tissue of a premolar retained on the side of, and anterior to, a segmental mandibular resection. Although abnormal, the pulp tissue showed evidence of a vascular supply 4 yr after mandibular surgery. A literature review was performed, and a discussion is given to explain the continued vascularity of the dentition through collateral and retrograde circulation. Despite the compromised dental circulation on the surgical side, unless radiographic evidence of periapical pathology occurs, endodontic therapy or extraction is not necessary. Due to the compromised nature of the circulation however, these teeth may be more susceptible to caries or restorative dental procedures that may lead to pulpal necrosis.

Aged↗
PubMed1997

Custom surgical stent for naris stenosis.

A technique has been described that allows accurate fabrication of a surgical nasal stent, made preoperatively, based on a mirror image of the shape of the normal naris. The advantage to the surgeon is a surgical stent that has the greatest accuracy possible preoperatively, plus the ability to remake the stent postoperatively with even more accuracy should it be needed. This stent can then be worn long term with minimal visibility and maximum patient acceptance during the critical months postoperatively when relapse is most likely.

Constriction, Pathologic↗
PubMed1997

Acidosis induces hyperpermeability in Caco-2BBe cultured intestinal epithelial monolayers.

We previously demonstrated that ileal mucosal acidosis in pigs reversibly increases intestinal permeability to hydrophilic macromolecules, even in the absence of tissue hypoxia [A.L. Salzman, H. Wang, P.S. Wollert, T.J. Vandermeer, C.C. Compton, A.G. Denenberg, and M.P. Fink. Am. J. Physiol. 266 (Gastrointest, Liver Physiol, 29): G633-G646, 1994]. In an effort to further explore the mechanism(s) underlying this phenomenon, we examined the effect of acidic pH on the permeability characteristics of cultured Caco-2BBe (human intestinal epithelial) cells grown as monolayers on permeable supports. Permeability was determined by measuring the mucosal-to-basolateral flux of fluorescein disulfonic acid (FS; mol wt 478 Dal, fluorescein isothiocyanate-labeled dextran (FD4; average mol wt 4 kDa), or [3H]mannitol. Incubation of monolayers under hypercarbic conditions or with acidific bicarbonate-free medium significantly increased permeability to FS, FD4, and mannitol in a manner dependent on both time and pH. Incubation in medium at pH 5.43 for 24 h increased the release of lactate dehydrogenase and decreased the intensity of staining with calcein-acetoxymethyl ester, findings that are indicative of plasma membrane injury; nevertheless, the percentage of nonviable cells did not increase. Ultrastructural analyses revealed evidence of increased paracellular trafficking of horseradish peroxidase after incubation of monolayers under acidic conditions. Fluorescence confocal microscopy and temperature studies demonstrated that incubation at pH 5.43 induced an increase in both the intracellular uptake of FD4 and the activation energy for FS permeation across Caco-2BBe monolayers, respectively, suggesting increased transcellular permeation. Exposure to acidic conditions also decreased cellular levels of ATP. We conclude that acidosis increases both paracellular and transcellular permeability to hydrophilic macromolecules and leads to depletion of ATP.

Acidosis↗
PubMed1995

Nitric oxide dilates tight junctions and depletes ATP in cultured Caco-2BBe intestinal epithelial monolayers.

We tested the hypothesis that nitric oxide (NO) modulates the permeability of tight junctions in a model intestinal epithelium (Caco-2BBe monolayers). Incubation with sodium nitroprusside (SNP) resulted in time- and concentration-dependent decreases in transepithelial resistance. Permeability to fluorescein sulfonic acid increased during incubation for 24 h in the presence of 1.25 mM SNP, 5 mM S-nitroso-N-acetylpenicillamine (SNAP), or 1% NO gas. SNP-induced hyperpermeability was not due to loss of cell viability, as confirmed by intact ultrastructure, unaltered lactate dehydrogenase release, and ability to recover baseline permeability. Incubation with SNP increased permeability but only minimally increased intracellular levels of guanosine 3',5'-cyclic monophosphate (cGMP). Incubation with Escherichia coli heat-stable enterotoxin greatly increased cGMP levels with only a minimal effect on permeability. Cellular ATP levels decreased after incubation with SNP, SNAP, or gaseous NO. Incubation with SNP led to diminished fluoresceinphalloidin staining of junctional actin (confocal microscopy) and widened tight junctions (electron microscopy). We conclude that NO reduces ATP levels and reversibly increases the permeability of tight junctions in cultured Caco-2BBe cells.

Adenosine Triphosphate↗
PubMed1994

The use of a photoprotective agent to increase the color stability of a tinted extraoral prosthetic silicone.

PURPOSE: This study investigated the use of ultraviolet-absorbing or photoprotective agents as a method of decreasing the color changes caused by ultraviolet radiation on an intrinsically tinted facial prosthetic material. MATERIALS AND METHODS: Silastic MDX 4-4210 (Dow Corning Corp, Midland, MI) was the facial prosthetic material studied. It was intrinsically tinted with talc and nylon flock to approximate the color of skin. Three brands of commercially available sunscreens with sun protective factor (SPF) of 15 were placed on the surface of the cured silicone samples. The samples were rotated in an ultraviolet radiation chamber for 300 hours. A control group was placed in the dark for 300 hours. The second phase of the experiment had para-aminobenzoic acid (PABA) added to the tinted silicone. All samples were measured with a spectrophotometer at the beginning and at the end of 300 hours, and a delta E was obtained. RESULTS: None of the sunscreens provided any ultraviolet radiation protection to the silicone. The addition of PABA caused a significant color degradation of the silicone. CONCLUSIONS: No photoprotective agent tested provided any significant level of ultraviolet radiation protection for silastic MDX 4-4210.

Humans↗
PubMed1994

Immuno-EM localization of the beta 1 integrin subunit in wet-cleaved fibronectin-adherent fibroblasts.

Using immuno-EM, we have studied the distribution of the beta 1 integrin subunit in chicken embryo fibroblasts allowed to adhere and spread for 3 hours on a fibronectin-coated surface in serum-free medium. The cells were wet-cleaved, which removed most of the cell body, yielding ventral plasma membranes with little, and sometimes virtually no, associated cytoskeleton. The beta 1 integrin subunit was detected with antibodies against the cytoplasmic domain. In immune fluorescence, it colocalized with adhesion plaques, in a punctate staining pattern, and often seemed to be at the periphery of the plaque. By immuno-EM, beta 1 was in fact found in discrete clusters, not throughout the plaque. In deep-cleaved cells from which virtually all cytoskeleton was removed, clusters could often be seen to be located on fibronectin fibrils. Furthermore, beta 1 was present in clusters at the cell margins, and isolated or in small groups at the very edge of the cell. When fibronectin synthesis, and consequently fibril formation, was inhibited by cycloheximide, large adhesion plaque-like structures were formed at the cell margin. This phenotype was reversed by addition of soluble fibronectin, which was incorporated into fibrils. As in normal plaques, talin and vinculin were present, the plasma membrane was very close (10-20 nm) to the substratum and the fibronectin layer underneath was removed. These plaques did contain beta 1 integrins but they were not in clusters. These observations indicate that the talin-vinculin network of an adhesion plaque is normally anchored to the substratum at discrete beta 1 integrin clusters that may be located on fibronectin fibrils, and that elsewhere the plaque is not necessarily attached to the substratum by interaction of integrins with matrix proteins. In the absence of fibronectin fibrils, adhesion plaque-like structures can be formed, but these are aberrant in size, location and fine structure.

Animals↗
PubMed1993

Surface treatment of a temporary soft liner for increased longevity.

This is a preliminary report on the use of several surface-conditioning agents on a commonly used temporary soft lining material. The surface of the material was treated with either poly(ethyl methacrylate) monomer, mono-poly glaze, or Minute-Stain glaze. Samples were compared with untreated soft liner before and after it was worn by a patient for 30 days. The scanning electron microscope was used to analyze samples. Initially the surface of all samples was intact, with the samples treated with mono-poly glaze and Minute-Stain glaze having fewer irregularities. After 30 days, untreated liner and that treated with monomer showed severe wear with resultant exposure of generalized pits and holes. Most of the defects represented exposure of subsurface air bubbles incorporated during mixing. The mono-poly glaze-treated specimen retained the glasslike appearance that it had before it was worn for 30 days. The Minute-Stain glaze specimen appeared irregular, although without the extensive pitting seen in the first two types of specimens.

Chemical Phenomena↗
PubMed1992

Bioelectric stimulation and residual ridge resorption.

The use of exogenous pulsed electromagnetic fields (PEMF) to stimulate the healing of nonunions and other long bone defects is common in medicine. This investigation used the dog model and image analysis of standardized radiographs to assess loss of residual ridge height following extractions. It demonstrates the effectiveness of intermittent PEMF to reduce the rate of residual ridge resorption. It further suggests there may be a causal relationship between residual ridge resorption and the alteration of endogenous bioelectric signals caused by the loss of teeth.

Alveolar Bone Loss↗
PubMed1992

Young children and television: the retention of emotional reactions.

In 6 experiments, we examined preschoolers' ability to interpret or remember the affective reactions of television characters. In 2 studies, children viewed a "Sesame Street" or "Cosby Show" segment, and then retold the story. In both, mention of the protagonists' affective states was low, with less than 1% of the reactions recalled. In 3 experiments (using muppet, cartoon, or human portrayals), we examined whether this low retention was due to an inability to interpret reactions, identify their emotional labels, or remember them across a short period. For muppet and cartoon shows, children accurately recognized labels for reactions immediately after portrayal, but showed significant reductions in recognition memory by the end of the show. For human portrayals, subjects showed accurate recognition immediately after presentation, as well as after the show. In a final experiment, free descriptions of the reactions were assessed. Correct description was significantly higher for basic emotions than complex emotions.

Child Development↗
PubMed1991

Custom lip shield for chronic actinic cheilitis.

Chronic actinic cheilitis is a premalignant lesion related to excessive exposure to the sun. Those with fair complexions and blond hair, and those who work outside are susceptible to this disease. This article describes the fabrication of a custom lip shield to protect the lower lip from the sun in highly susceptible individuals.

Biocompatible Materials↗
PubMed1988

Changes in the mandibular angle in the edentulous state.

Several textbooks of anatomy and at least one prosthodontic text make unsupported statements that the mandibular angle widens in the edentulous state. A search of the literature for support of those statements shows a disparity in conclusions on the subject. Several reports merely make statements that the angle does widen in the edentulous mandible. These articles present no original research. There are reports in the literature that lend some verification of the widening of the mandibular angle. However, an approximately equal number report nonwidening of the angle in the edentulous state. From these conflicting reports it would seem that if indeed there is a widening of the mandibular angle in the edentulous state, it is slight. This is verified by the results of this study which shows a mean increase of 2.4 degrees in the edentulous state (p = .001). The mean edentulous angle in this study was 126.3 degrees. This does not come close to the 140 degrees mentioned in two anatomy texts. If statements are to be made in the literature concerning this widening of the edentulous mandibular angle, they should be qualified with the words "slight widening." Several articles have stated that dentures prevent widening of the mandibular angle. This conclusion is refuted by a preliminary study in which we measured the mandibular angles of edentulous men patients who have never worn dentures. Sixty-eight angles were measured on 34 Panelipse radiographs.(ABSTRACT TRUNCATED AT 250 WORDS)

Cephalometry↗
PubMed1988

Passavant's ridge in patients with soft palatectomy.

Very little is known about the developmental aspects of Passavant's ridge. Several studies have looked at the prevalence of Passavant's ridge in the cleft palate patient where palatopharyngeal insufficiency has been present from birth. No one has reported on the prevalence of Passavant's ridge in adults with acquired soft palatal defects that result in palatopharyngeal insufficiency. This information would add to our knowledge of the developmental aspects of formation of Passavant's ridge. In this study, 29 soft-palatectomy patients were examined with an oral panendoscope for presence of Passavant's ridge. Eighty-three percent of the patients had Passavant's ridge during speech; 17 percent did not. In the 83 percent that had the ridge, the intensity of movement varied and was equally distributed among minimal, moderate, and extreme movement.

Adult↗
PubMed1987

Custom cervical splint for use during head and neck surgery.

A custom-made plaster cervical/occipital splint was described that was made to immobilize a patient with vertebral metastases during neck surgery. This is a single example of a problem solved by the cooperation between the head and neck surgeon and the maxillofacial prosthodontist.

Adult↗
PubMed1985

The role of the maxillofacial prosthodontist in detection of recurrent head and neck cancer.

Maxillofacial prosthodontists are in a unique position to aid in the detection of recurrent and secondary malignancies of the head and neck cancer patient. This is related directly to their intimate knowledge of normal and abnormal oral anatomy and to the large amount of time they spend with patients during treatment and follow-up. I have detected many recurrent and secondary tumors during the few years I have been in a relatively low volume maxillofacial prosthetics practice. The patient's recall visits to the maxillofacial prosthodontist should be evenly spaced between the patient's visits to the head and neck surgeon when possible. By earlier detection and immediate referral to the surgeon, there is the possibility of a higher long-term cure rate in head and neck cancer patients who are receiving maxillofacial prosthetic treatment.

Head and Neck Neoplasms↗
PubMed1983

Palatopharyngeal anatomy and physiology.

Current literature concludes that the levator veli palatini and the musculus uvulae are the muscles primarily responsible for palatopharyngeal closure during speech in the normal individual. As a compensatory mechanism in approximately one third of patients with palatopharyngeal insufficiency, the superior constrictor muscle may be active in the form of Passavant's ridge. This ridge occurs infrequently in normal speakers. There is some evidence that this conclusion is too simplistic. There may be more individual variation involved than admitted or understood at present.

Humans↗