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Biomedical subjects

S Hamlet

Publications and source records attributed to S Hamlet.

At least 19 recordsLinked to original sources
PubMed2006

Prostaglandin E2 enhances transforming growth factor-beta 1 and TGF-beta receptors synthesis: an in vivo and in vitro study.

The aims of this study were to determine how Prostaglandin E2 (PGE2) locally applied affected the immunodistribution of latent transforming growth factor-beta 1 (TGF-beta1), and how the eicosanoid modified TGF-beta1 release and TGF-beta receptors gene expression in cultured osteoblasts. PGE2 locally delivered on the rat mandible at doses of 0.1 and 0.05 mg/day, but not 0.025 mg/day, over 20 days significantly increased latent TGF-beta1 immunodistribution (P<0.001), comparing with a placebo-treated group. Cultured osteoblasts stimulated with 10(-5) or 10(-7)M PGE2 significantly varied the level of activated TGF-beta1 released into supernatants at different experimental periods compared with negative and positive controls. TGF-beta receptor type I gene expression was significantly increased in osteoblasts (P<0.01) after 10 days of treatment with 10(-5) and 10(-7)M PGE2, whereas 10(-3) M PGE2 produced the opposite effect. It is concluded that PGE2 may stimulate bone deposition by affecting TGF-beta pathway. This effect on the pathway appears to be dose-dependent.

Activin Receptors, Type I↗
PubMed2006

Deficiency of iNOS contributes to Porphyromonas gingivalis-induced tissue damage.

Periodontitis is a chronic inflammatory disease that results in extensive soft and hard tissue destruction of the periodontium. Porphyromonas gingivalis possesses an array of virulence factors and has been shown to induce expression of inducible nitric oxide synthase (iNOS) in inflammatory cells. The aim of this study was to investigate the effect of eliminating iNOS in a murine model of P. gingivalis infection. This was achieved by utilizing a P. gingivalis-induced skin abscess model, and an alveolar bone loss model employing an oral infection of P. gingivalis in iNOS knockout mice. The results indicated that iNOS knockout mice exhibit more extensive soft tissue damage and alveolar bone loss in response to P. gingivalis infection compared to wild-type mice. The local immune response to P. gingivalis in iNOS knockout mice was characterized by increased numbers of polymorphonuclear monocytes, while the systemic immune response was characterized by high levels of interleukin-12. The iNOS is required for an appropriate response to P. gingivalis infection.

Abscess↗
PubMed2005

The distribution of Tannerella forsythia in an adolescent and adult population.

BACKGROUND: The fact that Tannerella forsythia, an important periopathogen, is difficult to cultivate from mixed infections has impeded precise estimates of its distribution within a given population. In order to discern T. forsythia alone from the mixed infection of plaque, the use of sensitive 16S ribosomal RNA based polymerase chain reaction (PCR) detection is necessary. OBJECTIVES: The aim of the present study was to determine the distribution of T. forsythia in an adult and in an adolescent population. MATERIAL AND METHODS: Subgingival plaque samples were obtained from 498 Australian adults and from 228 adolescent subjects from Manchester, UK. Tannerella forsythia was detected using PCR and confirmed by restriction analysis. Semi-quantitation of the organisms was carried out using two specific primers of differing sensitivities. RESULTS: In the adolescent population, 25% were found to carry T. forsythia, albeit in relatively low numbers. In the adult population, a total of 37.8% and 11% were found to carry the organism with primer 2 and primer 1, respectively, suggesting that around 27% had between 10(3) and 10(7) organisms. Although there was an apparent increased proportion of T. forsythia positive subjects in those aged > or = 50 years, this was not statistical significant. However, T. forsythia positive male smokers showed increased disease severity compared with T. forsythia negative subjects. CONCLUSION: This study has shown that at least 25% of the adolescent population carry low numbers of T. forsythia, whereas at least 37% of adults carry the organism, with some 11% having relatively high numbers. The relationship between T. forsythia and disease progression in these populations, however, remains to be determined.

Adolescent↗
PubMed2004

Persistent colonization with Tannerella forsythensis and loss of attachment in adolescents.

Colonization with Tannerella forsythensis may characterize the conversion of periodontally healthy sites into diseased sites. This three-year study describes the prevalence of T. forsythensis and its relationship to clinical loss of attachment (LOA) in a group of adolescents considered at risk of developing early chronic periodontitis. Adolescents with (LOA+) and without (LOA-) loss of attachment were examined at baseline and 1.5 and 3 yrs subsequently. On each occasion, attachment loss was measured on selected teeth, and the presence of T. forsythensis in their subgingival plaque samples was determined by PCR. T. forsythensis prevalence in LOA+ subjects at baseline (64%) increased to 82% and 86% on subsequent examinations. In contrast, prevalence of T. forsythensis in LOA- subjects was always significantly lower (25%, 36%, and 32%, respectively). The odds of loss of attachment were 8.16 times greater in subjects infected with T. forsythensis at each examination. These results suggest that T. forsythensis is strongly associated with loss of attachment in this adolescent population.

Adolescent↗
PubMed2001

A microbiological study of Papillon-Lefévre syndrome in two patients.

AIM: To analyse the microflora of subgingival plaque from patients with Papillon-Lefévre syndrome (PLS), which is a very rare disease characterised by palmar-plantar hyperkeratosis with precocious periodontal destruction. METHODS: Bacterial isolates were identified using a combination of commercial identification kits, traditional laboratory tests, and gas liquid chromatography. Some isolates were also subjected to partial 16S rDNA sequencing. Plaque samples were also assayed for the presence of Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans in a quantitative enzyme linked immunosorbent assay (ELISA) using monoclonal antibodies. RESULTS: The culture results showed that most isolates were capnophilic and facultatively anaerobic species-mainly Capnocytophaga spp and Streptococcus spp. The latter included S. constellatus, S. oralis, and S. sanguis. Other facultative bacteria belonged to the genera gemella, kingella, leuconostoc, and stomatococcus. The aerobic bacteria isolated were species of neisseria and bacillus. Anaerobic species included Prevotella intermedia, P. melaninogenica, and P. nigrescens, as well as Peptostreptococcus spp. ELISA detected P gingivalis in one patient in all sites sampled, whereas A. actinomycetemcomitans was detected in only one site from the other patient. Prevotella intermedia was present in low numbers. CONCLUSIONS: Patients with PLS have a very complex subgingival flora including recognised periodontal pathogens. However, no particular periodontopathogen is invariably associated with PLS.

Aggregatibacter actinomycetemcomitans↗
PubMed1997

Mastication and swallowing in patients with postirradiation xerostomia.

PURPOSE: Very little objective data has been reported on mastication and swallowing in xerostomic patients, which would substantiate presumed causal relationships between xerostomia and patient complaints. The purpose was to elucidate which components of mastication and swallowing were abnormal, and most directly related to xerostomia, and which appeared unaffected. METHODS AND MATERIALS: A retrospective analysis of timing events in mastication and swallowing was done using videofluoroscopic data for 15 cancer patients with xerostomia, and 20 normal controls. Scintigraphy was also used to determine oropharyngeal residue after a water swallow. Cancer treatment modalities included radiation therapy or chemoradiation therapy. RESULTS: For barium liquid and paste substances, timing measures were equivalent for controls and patients. Xerostomic patients took 46% longer to masticate a shortbread cookie, and timing for the initiation of swallowing was shorter, but duration of swallowing appeared unaffected. Oral and pharyngeal residues following the swallow were greater in the patient group. CONCLUSIONS: Xerostomia primarily affected mastication and oral manipulation of a dry, absorbent food material. Increased oral and pharyngeal residues after a water swallow are ambiguously related to xerostomia. The initiation and duration of the pharyngeal swallow was not abnormal.

Aged↗
PubMed1997

Prevalence of suspected periodontal pathogens identified using ELISA in adolescents of differing ethnic origins.

The aim of this study was to determine the prevalence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia in a group of adolescents and investigate the association of these organisms with various clinical parameters. A total of 527, 11-13-year-old children, of whom 333 (63%) were white Caucasian, 187 (35%) Indo-Pakistani and 7 (1%) Afro-Caribbean, participated in the study. Subgingival plaque samples, collected from the mesio-buccal of both upper first permanent molars using sterile paper points, were stored in phosphate buffered saline with 0.01% thiomersal and analysed for the presence of A. actinomycetemcomitans, P. gingivalis and P. intermedia using ELISA. The mesio-buccal sites of both upper 1st permanent molars were also examined and the presence/absence of supragingival plaque, subgingival calculus, bleeding on probing and pocket depths greater than 3 mm were recorded. The % of white Caucasian children in whom the monoclonal antibody identified at least 1 site with A. actinomycetemcomitans, P. gingivalis and P. intermedia were 4%, 3% and 2%, respectively, and for Indo-Pakistanis were 3%, 17% and 2%. The difference for P. gingivalis was statistically significant (p < 0.001). The associations between the clinical parameters and the 3 organisms were considered separately for both upper first molar sites. The prevalence of P. gingivalis was higher for sites with subgingival calculus, pockets > 3 mm and bleeding on probing (p < 0.01).

Adolescent↗
PubMed1996

Normal adult swallowing of liquid and viscous material: scintigraphic data on bolus transit and oropharyngeal residues.

Scintigraphic data are provided for 20 normal control subjects, 39-65 years of age. Each subject swallowed 10 cc of water and 10 cc of a more viscous material (1,100 centipoise) consisting of apple juice thickened with Thick-It, a commercial food thickener. The test substances were combined with 2.5 mCi Tc-99m sulfur colloid. Scintigraphic data were acquired in dynamic mode for 10 sec at 25 frames/sec as the subject swallowed. Time-activity (TA) data were used to compute transit times, percentage residues in the mouth and pharynx, percent ingested, and a derived swallow efficiency score. The liquid was ingested in a single swallow by all subjects, and 9 cc was actually transferred to the esophagus. In contrast, for the viscous material, 11/20 subjects performed a second clearing swallow within the 10-sec interval. On the first swallow with the viscous substance, an average of 7 cc was transferred to the esophagus. Scintigraphy offers an excellent technique for determining natural and preferred volumes for swallowing a variety of bolus consistencies, since it can quantify the volume of each swallow or partial swallow. In this group of subjects the oral discharge time was shorter with the viscous material than with the water, but the pharyngeal transit times were not significantly different for the two bolus consistencies. Numerical efficiency scores were lower for the viscous material, indicating that such a measure is bolus dependent.

Adult↗
PubMed1994

Larynx motion associated with swallowing during radiation therapy.

PURPOSE: A basis is presented for predicting the reduction in radiation dose to the larynx attributable to swallowing during radiation therapy treatment. METHODS AND MATERIALS: Laryngeal movement associated with swallowing can occur during radiation therapy even when the patient's head is immobilized. Data on the extent and timing of laryngeal motions and the frequency of swallowing were used to predict the effect such motion would have on accuracy of radiation dose to the larynx. RESULTS: In a nontracheostomized adult the larynx elevates approximately 2 cm during a swallow and moves anteriorly less than 1 cm. The normal frequency of swallowing in the supine position is once every 1-2 min. During therapy, the likelihood of a swallow occurring during an irradiation interval depended on the duration of the interval. For irradiation intervals less than 2 min long the ratio of number of swallows to number of intervals was 0.27. For irradiation intervals between 2-3 min long the ratio was 1.76. Based on conservative estimates of radiation field dimensions, larynx motion, and incidence of swallowing, the reduction in radiation dose attributable to swallowing during treatment would be approximately 0.5%. CONCLUSION: With small fields the total dose is only decreased by 0.5% with swallowing, so the change in the total dose is insignificant.

Deglutition↗
PubMed1994

Stethoscope acoustics and cervical auscultation of swallowing.

Frequency response characteristics of six popular stethoscopes are reported for the higher frequency range (to 3000 Hz) to supplement equivalent measurements for the lower frequencies (35-1000 Hz) published previously. Spectra of the sounds of swallowing from the throat, transduced with an accelerometer, demonstrate important frequency composition in this higher range. Two stethoscope models were found to have superior transmission characteristics for use in cervical auscultation of swallowing sounds.

Acceleration↗
PubMed1994

Quantifying aspiration in scintigraphic deglutition testing: tissue attenuation effects.

UNLABELLED: Scintigraphic studies for determining aspiration associated with swallowing have ignored error due to differential gamma attenuation in the patient by the various regions of the body. This study sought to estimate the magnitude of that error, and to assess the feasibility of providing individual attenuation corrections based on clinical data. METHODS: Relative attenuation for the pharynx, thorax and abdomen were determined from physical measurements employing an anthropomorphic phantom and 45 adult human subjects. A small sealed radioactive source of 2.5 mCi of 99mTc was placed inside the phantom at various locations within the upper digestive tract and respiratory system, and relative count rates determined via static scans with a gamma camera. Similar data for human subjects was obtained from clinical swallowing testing using a bolus of 2.5 mCi of 99mTc in 10 cc of water. RESULTS: The ratios representing relative counts were highly similar between the phantom and average human data. Test-retest replication of results was good for the abdominal reference and pharynx ratios--less so for the thorax. A procedure is described for estimating accuracy of percent aspiration calculation based on group data, using normalization coefficients derived for separate anatomical regions in the subglottic respiratory system. CONCLUSIONS: Error in percent aspiration calculation will depend on the amount and location of aspirate. Individual subject corrections based on the type of clinical data studied should be attempted with caution.

Adult↗
PubMed1993

The effect of swallowing bolus and head position on eustachian tube function via sonotubometry.

Eustachian tube function was evaluated by sonotubometry in otologically normal young adults. The purpose of the research was to determine if the incidence or duration of eustachian tube opening would be altered with changes in swallowing bolus volume or changes in head rotation. The subject performed multiple swallows of 10 cc water bolus and dry swallows (saliva), with the head in the straight-forward, turned right, and turned left positions. Both ears were evaluated. The average incidence and duration of eustachian tube opening for all swallows was 74% (398 msec). No significant differences were found with any combination of bolus type or head position, suggesting that neither liquid bolus volume nor head rotation need be controlled when sonotubometry is performed.

Adult↗
PubMed1992

Multiple swallows and piecemeal deglutition; observations from normal adults and patients with head and neck cancer.

The incidence of multiple swallows for liquid and paste, and the time delay between multiple swallows, was determined from videofluoroscopic records of modified barium swallow tests. In a comparison of liquid and paste, the overall incidence of multiple swallows did not differ, for either patients with head and neck cancer or normal controls. However, for liquid swallows the incidence in patients with cancer was abnormally high, predominantly in patients with pharyngeal cancer.

Adult↗
PubMed1992

Scintigraphic quantification of pharyngeal retention following deglutition.

A procedure is described for quantifying the amount of bolus material retained in the pharynx after completion of a swallow, using radionuclide swallow techniques. Data are derived from scintigraphic time-activity curves. The procedure takes into consideration the differential attenuation of radioactivity through various regions in the body, and expresses the result as a percentage of the total radioactivity in the ingested bolus. Illustrative examples are provided for swallows by normal individuals and patients with head and neck cancer.

Adult↗
PubMed1990

Acoustic technique for determining timing of velopharyngeal closure in swallowing.

A pure tone sound source was introduced at a nostril and monitored by a miniature accelerometer on the throat. During velopharyngeal closure in a swallow, the pure tone component in the accelerometer signal was attenuated. Throat accelerometer recordings were made simultaneously with videofluoroscopy of a modified barium swallow in adults with normal velopharyngeal mechanisms. It was verified that the period of sound attenuation corresponded to the period of velar closure. This noninvasive method of monitoring otherwise silent velopharyngeal closure holds promise for normative studies on swallowing function, as an adjunct method in longitudinal assessment, and as a training aid.

Adult↗
PubMed1987

Bovine ocular squamous cell carcinoma: superoxide dismutase and catalase levels.

Considerable evidence exists for the production of free radicals in the eye region after exposure to ultraviolet light. Failure to remove these radicals adequately may be important in the predisposition of Hereford cattle to ocular carcinoma. The levels of two enzymes, superoxide dismutase and catalase, involved in the removal of superoxide anion and hydrogen peroxide, were compared in Hereford cattle predisposed to ocular carcinoma and a resistant breed, Droughtmaster cattle. The results demonstrate comparable levels of superoxide dismutase in the two breeds in both eye tissue and erythrocytes. Catalase levels also were the same in both breeds. Increased incidence of ocular carcinoma in Herefords does not appear to be due to a deficiency in either superoxide dismutase or catalase.

Animals↗