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Biomedical subjects

R Lunn

Publications and source records attributed to R Lunn.

17 recordsLinked to original sources
PubMed1999

Pretreatment assessment and dental management of patients with nasopharyngeal carcinoma.

Patients who present with nasopharyngeal carcinoma (NPC) require through oral and dental assessment prior to treatment of the malignancy. We assessed the oral status of 57 consecutive patients with a diagnosis of NPC. In this study, identified risk factors for NPC were seen to be different in Asian versus non-Asian patients. Epstein-Barr virus seropositivity was seen in all Asian patients and in 69% of non-Asian patients (P = 0.00006), and reported alcohol use was greater in the non-Asian patients. In this study it was found that 68% of dentate patients required dental extractions primarily due to periodontal disease. Even in patients who reported receiving regular dental care (28%) extractions prior to radiation therapy were suggested. Oral complications of radiation therapy were reported by 84% of patients, with the most common being xerostomia. Clinical diagnosis of candidiasis (16%), rampant caries (10% of dentate patients) and difficulties with dentures (25% of denture wearers) were noted. In addition to pretreatment assessment, continuing oral and dental management is needed for patients with NPC.

Adult↗
PubMed1998

Periodontal attachment loss in patients after head and neck radiation therapy.

OBJECTIVE: The purpose of this study was to determine the potential impact of head and neck radiation therapy on the progression of periodontal attachment loss. STUDY DESIGN: Ten patients who received unilateral radiation fields that included the dentition were assessed before radiation treatment and after irradiation at a mean age of 6.01 years. Complete oral, dental, and periodontal examinations were completed by one examiner. The results were assessed through use of paired t tests. RESULTS: More teeth were extracted because of periodontal disease in the field of radiation after irradiation. Remaining teeth in the radiated volume showed an increase in probing depth of 0.82 mm in comparison with 0.40 mm for teeth in the nonradiated region (P = .05). Recession on the facial aspects was 1.88 mm for teeth in the radiated volume and 1.16 mm for teeth in the nonradiated region (P = .001), and recession on the lingual aspects was 2.10 for teeth in the radiated volume and 0.91 for teeth in the nonradiated region (P = .05). Mean total attachment loss was 2.81 mm for teeth in the radiated sites; this compared with 1.43 mm for teeth in the nonradiated sites (P = .003). Increased mobility of teeth in the high-dose fields was seen (P = .02). CONCLUSIONS: This study showed that tooth loss and greater periodontal attachment loss occur in teeth that are included within high-dose radiated sites of patients treated with irradiation therapy for cancer. These findings should be considered in preradiation treatment planning.

Adult↗
PubMed1998

Expression of the Rh-related glycoprotein (Rh50).

The Rh50 glycoprotein is suspected of being involved in Rh antigen expression. We prepared Rh50 cDNA from a human bone marrow library by polymerase chain reaction and then subcloned this cDNA into various vectors. The vector containing Rh50 cDNA produced a 30-kDa nonglycosylated form of Rh50 in a rabbit reticulocyte lysate system and produced partially glycosylated Rh50 (32 kDa) when microsomes were added to the system. COS-1 cells transiently transfected with the vector containing Rh50 cDNA produced partially glycosylated Rh50 (32 kDa) recognized by a Rh50-specific antibody. Surface expression of Rh50 in K562 cells was also detected by flow cytometry using mouse monoclonal antibody (2D10) specific to Rh50. Partially glycosylated Rh50 (32 kDa) was again isolated from the lysates of K562 cells metabolically labeled with [35S]-methionine or [3H]-mannose using anti-Rh50 antisera. These systems (K562 and COS-1 cells) should prove useful for studying the transport of Rh proteins within the cell and the necessary components needed for Rh antigenicity at the cell surface.

Animals↗
PubMed1996

Prophylaxis of candidiasis in patients with leukemia and bone marrow transplants.

OBJECTIVES: The increased risk for systemic fungal infection and the potential fatal consequences of disseminated candidiasis in bone marrow transplant patients has prompted study of prophylaxis and early treatment of candida colonization and infection. STUDY DESIGN: Patients with leukemia who received fluconazole prophylaxis were compared with a concurrent group of patients not given prophylaxis for fungal organisms. RESULTS: A trend to reduction of oropharyngeal colonization by Candida albicans was seen (p = 0.07) although no significant differences in systemic candidiasis were seen. In patients with documented systemic candidiasis, oral colonization was present and systemic infection was identified after the development of ulcerative oral mucositis. CONCLUSIONS: Our results support the potential of fluconazole to reduce oropharyngeal colonization by Candida albicans, however, we did not show prophylaxis of oral candidiasis or systemic candidiasis. These findings and reports of fluconazole-resistant candidal species and a rising number of cases of infection as a result of Candida krusei indicate the need for further studies of prophylaxis of candidal infection in patients who are anticipated to develop profound neutropenia.

Adolescent↗
PubMed1996

Effects of compliance with fluoride gel application on caries and caries risk in patients after radiation therapy for head and neck cancer.

The use of fluoride gel applied in a custom tray once daily has become standard for patients who have xerostomia after undergoing radiation therapy. Compliance may be poor as a result of the inconvenient method of application and because many patients with head and neck cancer have poor health behaviors. Our aim was to investigate the effect of compliance with fluoride gel application on caries and caries risk. Patients were prescribed neutral sodium fluoride gel (5000 ppm) before undergoing radiotherapy Fifty-two patients were willing to visit the dental clinic for dental examination, measurement of saliva, and quantitative culture of Streptococcus mutans and lactobacillus species. Before radiotherapy was performed, decayed, missing, and filled surfaces data were recorded for all patients in the study. Of these patients, 27 used fluoride gel once daily, as directed. Radiation dose, number of fractions, and duration of radiation had a significant inverse effect on postradiotherapy whole resting saliva (p = 0.04, p = 0.01, and p = 0.01) and on whole stimulated saliva (p = 0.02, p < 0.01, and p < 0.01). Patients with a subjective feeling of dry mouth had significantly less saliva production at rest (p = 0.01) and on stimulation (p = 0.01). A trend toward reduction of S. mutans counts was seen in those patients who used their fluoride gel regularly (p = 0.057). High lactobacilli counts were found in the patients with high and low compliance with fluoride gel use. Differences in the mean caries incidence between those who reported compliance with daily fluoride application and those who did not comply were not found significant because of the large SD in the patient groups, although differences in the mean for these groups were seen. The lack of a statistically significant difference may be due to the multiple factors associated with caries. Therefore patient care must be individualized, and patients must be assessed at regular intervals to determine the caries risk and caries activity to provide guidance for maintenance of the dentition.

Adult↗
PubMed1995

Red cell surface cysteine residue (285) of D polypeptide is not essential for D antigenicity.

BACKGROUND: Only one surface cysteine residue (285) has been thought to be involved in D antigenicity, according to studies using lyophilized or nonlyophilized red cell membranes. However, it has been reported that a 17-kDa chymotryptic fragment containing the N-terminus but not this cysteine residue is associated with D antigenicity. STUDY DESIGN AND METHODS: The role of the sulfhydryl (SH) group in D, c, and E antigenicity is assessed by using intact red cells treated with the reagents N-ethylmaleimide, 5,5'-dithiobis(2-nitrobenzoic acid), and 2-(4'-maleimidylanilino)- naphthalene-6-sulfonic acid. Antigenicity was appraised by hemagglutination titers and immunoprecipitation using human anti-D, -c, and -E. RESULTS: Treatment with N-ethylmaleimide or 5,5'-dithiobis(2-nitrobenzoic acid) at various concentrations (< or = 5 mM) or for various times (< or = 120 min) did not cause significant decrease in hemagglutination titers as compared to untreated intact red cells. Moreover, immunoprecipitation of Rh antigen-carrying peptides by human anti-D was not affected by prior treatment with N-ethylmaleimide or 2-(4'maleimidylanilino)-naphthalene-6-sulfonic acid. Efficacy of blockage of SH groups was demonstrated by inhibition of palmitic acid uptake by the Rh polypeptides for prior treatment with N-ethylmaleimide and by the presence of fluorescent Rh polypeptides for prior treatment with 2-(4'maleimidylanilino)-naphthalene-6-sulfonic acid. CONCLUSION: SH group involvement is not essential for D, c, or E antigenic expression in intact red cells.

Antibodies, Monoclonal↗
PubMed1995

A combined analysis of a toothbrush, foam brush, and a chlorhexidine-soaked foam brush in maintaining oral hygiene.

Oral hygiene in immunocompromised patients is important in preventing oral infection and may be important in preventing systemic infections. By mechanically reducing bacterial plaque levels in the oral cavity, the risk of infection may be reduced. Foam brushes have been shown to be ineffective in controlling plaque levels and gingivitis. In a 2-week trial, we demonstrated that using a foam brush soaked in chlorhexidine reduces plaque and controls gingivitis as effectively as using a toothbrush. Foam brushes soaked in chlorhexidine should be used when toothbrushing cannot be performed.

Analysis of Variance↗
PubMed1994

Rh(D) antigen expression and isolation of a new Rh(D) cDNA isoform in human erythroleukemic K562 cells.

Human erythroleukemic K562 cells are known to have several erythroid properties. K562 cells possess Rh mRNAs, but expression of Rh proteins has not previously been reported. We immunoprecipitated Rh protein from K562 cell lysate using rabbit anti-Rh and detected Rh(D) antigens on K562 cells using fluorescence-activated cell sorting (FACS). These results suggest that K562 cells will be useful as an expression model for most Rh antigens. We also cloned a new Rh(D) cDNA isoform (RhK562-II), from a K562 cDNA library using polymerase chain reaction (PCR) with 5' and 3' end oligonucleotides of the published Rh(e/E) antigen encoding cDNA sequence as primers. Sequence analysis showed that RhK562-II is composed of 951 nucleotides (316 amino acids), identical to the first 939 nucleotides (exons 1 to 6) of one of the Rh(D) cDNAs (RhXIII), except for nucleotide 654 (C-->G exchange). However, this exchange is the same as that of another published Rh(D) cDNA (RhPII cDNA). RhK562-II is deprived of exons 7 and 8 (nucleotides 940 to 1,153), followed by an identical sequence up to the 3' end of the open-reading frame of the RhXIII cDNA, which causes a frame-shift mutation and produces a premature stop codon. In vitro expression of RhK562-II using the transcription and translation rabbit reticulocyte lysate system produced two major Rh-related proteins (30 kD and 25 kD), which were immunoprecipitated by rabbit polyclonal anti-Rh and separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

Amino Acid Sequence↗
PubMed1994

Enhancing the effect of oral hygiene with the use of a foam brush with chlorhexidine.

The maintenance of oral hygiene for hospitalized patients, particularly medically compromised and immune compromised patients, may reduce the risk of oral and systemic infection. Foam brushes have been recommended for use in these populations, however, the use of a foam brush has not been shown to be an acceptable alternative to the use of a toothbrush. In this study, we demonstrate that the use of a foam brush saturated with chlorhexidine was equally effective in measures of plaque levels and gingivitis as was the use of a toothbrush. Therefore if a toothbrush cannot be used in hospitalized patients, an alternative may be the use of chlorhexidine applied with a foam brush.

Adult↗
PubMed1993

Expression of the 32-Kd polypeptide of the Rh antigen.

To develop procedures for the expression of Rh antigen-containing proteins, we prepared a previously cloned Rh cDNA by isolation from a human bone marrow library using polymerase chain reaction (PCR). The cDNA that encodes either Rh(E) or (e) antigens was inserted into a vector (pGEM7ZRh) and transcription/translation performed in a reticulocyte lysate system. This produced a major (32 Kd) and minor (30 Kd) protein band in the region of sodium dodecyl sulfate (SDS) gels where Rh proteins are known to migrate. These same two proteins were immunoprecipitated by a rabbit anti-Rh antibody preparation that reacts with all Rh proteins, confirming that Rh protein was expressed in this cell-free system. Transient expression of Rh protein in COS-1 cells was also accomplished using a transfection vector (pBC12BIPLRh) containing inserted Rh cDNA. COS-1 cells transfected with this vector also produced a 32-Kd protein band that formed an immune complex with rabbit anti-Rh, while cells transfected with the same vector minus the Rh cDNA insert did not yield any detectable Rh immune-complexed protein. This system should prove useful for studying the transport of Rh proteins within the cell and the expression of Rh antigenicity at the cell surface.

Animals↗
PubMed1993

Interactions between short-term vertical phoria adaptation and nonconjugate adaptation of vertical pursuits.

We have demonstrated that short-term vertical position-specific phoria adaptation contributes to nonconjugate adaptation of vertical pursuits, but not to nonconjugate adaptation of vertical saccades. Binocular adaptation to multiple stationary vertical disparities resulted in both nonconjugate pursuits and phoria aftereffects but had little effect on the early step component of vertical saccades. Similarly, binocular nonconjugate adaptation of vertical pursuits produced both nonconjugate pursuits and fixation phoria aftereffects. Position-specific adaptation of nonconjugate pursuit was demonstrated by adapting to disparate motion in the upper field which resulted in nonconjugate pursuit aftereffects that were greater in the upper than the lower hemifield. These nonconjugate pursuits were accompanied by position-specific phoria aftereffects, indicating that common mechanisms underlie adaptation of vertical phoria and nonconjugate pursuits.

Adaptation, Ocular↗
PubMed1993

Directionally selective short-term nonconjugate adaptation of vertical pursuits.

We investigated the contribution of fixation phoria and dynamic processes to short term (1 hr) nonconjugate adaptation of vertical pursuits. Unequal aftereffects were observed in vertical phoria measured during stationary gaze and during pursuits (static fixation and pursuit phorias) demonstrating direction-specific aftereffects of pursuit phoria that were not evident in measures of fixation phoria. A linear model describes the combination of fixation phoria and three dynamic direction-specific components which include a gain component that determines nonconjugate velocity, a phase component that determines the relative position of binocular pursuits, and a small position specific pursuit phoria adjustment process. Larger position-specific variations of fixation phoria appear to compensate for inappropriate or incomplete adaptive changes produced by two of the dynamic mechanisms which are not position specific.

Adaptation, Ocular↗
PubMed1993

Spatial aspects of vertical phoria adaptation.

Vergence adaptation to vertical disparity spreads to unadapted directions of gaze. The spatial spread function for prism adaptation was estimated from aftereffects of a vertical disparity presented at a single position. Constraints limiting the spatial spread of adaptation were investigated with two stimuli of opposite disparity (hyper and hypo), presented at two different eye positions with a separation that varied from 6 to 18 deg in either the horizontal or vertical meridian. On average, phoria adaptation to the single point paradigm spread uniformly across the entire 18 deg test field. A resolution limit for adaptation to the two point paradigm was demonstrated by a reduction of phoria aftereffects with decreasing target separation (crowding). Vertical phoria aftereffects were reduced more by horizontal than by vertical crowding. A disparity gradient limit was demonstrated for a fixed target separation by a reduction of gain (phoria change/stimulus disparity) with increasing stimulus disparity.

Adaptation, Ocular↗
PubMedDate not supplied

Oral management of the cancer patient. Part I: Overview of cancer and oral cancer.

As the population of older Canadians (50 + years) grows, so the number of people-diagnosed with some form of cancer increases. Through early detection, diagnosis, and advances in treatment of these cancers, the number of long-term survivors is also increasing. It is, therefore, predictable that the role of all health care providers will increase in the areas of diagnosis, treatment, and assistance with their continued care. In this first of a three part series, an overview of cancer (and in particular oral cancer) is presented as well as statistical information on cancer incidence and mortality, etiology, treatment modalities, head and neck cancers, their signs and symptoms, prognosis, and pre-treatment dental evaluations. The second installment will review the care and management of patients undergoing chemotherapy and the third will discuss the care and management of patients receiving radiation therapy for head and neck cancers. The series will focus specifically towards the oral implications impacting on dental hygiene services.

Adolescent↗
PubMedDate not supplied

Oral management of the cancer patient. Part II: chemotherapy.

This second of a three-part series reviews chemotherapy treatment and the responsibilities dental care providers have for patients in all phases of this type of cancer treatment. The goals of dental care are to maintain the integrity of the oral mucosa, prevent secondary infection, provide relief, and assist in maintaining dietary intake. The dental hygienist plays a key role in the recognition, treatment or monitoring of dental conditions that could cause complications to the patient during and post chemotherapy, as well as in educating and motivating the patient in optimal oral self-care.

Antineoplastic Agents↗