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Biomedical subjects

C A van Hasselt

Publications and source records attributed to C A van Hasselt.

At least 19 recordsLinked to original sources
PubMed2007

The choice of chromogen and reliability of contact rhinoscopy in the irradiated nasopharynx.

A cross-sectional randomised single blind study was conducted to assess how concentrations of chromogen (vital stain) and the characteristics of the assessors affect the assessment of contact rhinoscopy. Twenty-eight patients who had undergone external radiotherapy for nasopharyngeal carcinoma were assessed by contact rhinoscopy using 0.5 per cent and 1 per cent methylene blue stain on opposite sides of the nasopharynx. Three independent observers assessed the visual clarity of the 45 contact endoscopic images showing squamous metaplasia according to a visual analogue scale. The intraclass correlation coefficients were 0.916 to 0.957 and 0.839 to 0.964 for intra-observer reliability of assessors in the groups of 0.5 per cent and 1 per cent stains, respectively. The intraclass correlation coefficients for inter-observer reliability of assessors were 0.884 and 0.885 in the groups of 0.5 per cent and 1 per cent stains, respectively. The mean scores of clarity of the cellular details were statistically higher in the group of 1 per cent stain among all assessors. These results showed that the assessment of squamous metaplasia by contact endoscopy is highly reliable irrespective of the clinical experience and knowledge of histopathology of the assessors. One per cent methylene blue should be the vital stain of choice in contact endoscopy.

Adult↗
PubMed2005

Cell death induced by ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid in anaplastic thyroid carcinoma cells is via a mitochondrial-mediated pathway.

The chemical compound ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F), isolated from the Chinese herbal medicine plant Pteris semipinnata L, has been known to exert antitumor activity. However, the molecular mechanism of the action is not understood. In this study we demonstrated that apoptotic cell death induced by 5F in FRO cells was concentration- and time-dependent. The rapid increase in intracellular reactive oxygen species (ROS) levels was involved in the mechanism of cell death. c-Jun N-terminal kinase (JNK) activation and G2 block were related to cell death induced by 5F. Extracellular signal-related kinase (ERK) and p38 were also activated, but as survival signals in response to 5F treatment to counteract the induction of cell death. In the process of the induction of apoptotic cell death, Bax translocated into mitochondria, a reduction in Delta psi(m) was observed and a release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria into the cytosol occurred, indicating that cell death induced by 5F was through a mitochondrial-mediated pathway.

Apoptosis Inducing Factor↗
PubMed2004

Heme oxygenase-1 protects against apoptosis induced by tumor necrosis factor-alpha and cycloheximide in papillary thyroid carcinoma cells.

Heme oxygenase-1 (HO-1) plays a role in the resistance to apoptosis of several types of cells, but its role in the development of thyroid cancer is unknown. In this study, we investigated the regulation of HO-1 in human papillary thyroid carcinoma cells (KAT5). The results show that HO-1 is significantly induced by hemin and cadmium. In addition to inducing HO-1, hemin and cadmium also cause a rise in the levels of p21, a cyclin-dependent kinase inhibitor. Cells with increased levels of HO-1 and p21 were more resistant to apoptotic stimuli than cells with normal levels. The cells resistant to apoptosis also displayed an increased arrest at the G(0)/G(1) phase of the cell-cycle. The induced levels of HO-1 and p21 were significantly reduced by p38 mitogen-activated protein kinase (p38 MAPK) and extracellular-regulated kinase (ERK) inhibitors. More importantly, KAT5 cells regained their sensitivity to apoptotic stimuli after they were treated with these kinase inhibitors, indicating that p38 MAPK and ERK are required for the resistance to apoptosis conferred by HO-1. Furthermore, we demonstrated that increased levels of HO-1 and p21 expression are associated with an increase in the activity of NF-kappaB and that inhibiting NF-kappaB leads to a block in the induction of HO-1 and p21. In summary, this study reveals that an increase in the level of HO-1 markedly reduces the sensitivity of papillary thyroid carcinoma cells to apoptotic stimuli. The HO-1 pathway of apoptosis resistance is associated with an increase in the levels of p21, involves a p38 MAPK and ERK-mediated mechanism and can be suppressed by inhibiting NF-kappaB.

Apoptosis↗
PubMed2004

Resistance to apoptosis of HPV 16-infected laryngeal cancer cells is associated with decreased Bak and increased Bcl-2 expression.

Human papillomavirus type 16 (HPV 16) plays an etiological role in human laryngeal carcinoma. Apoptosis is closely associated with various biological processes including oncogenesis. This study investigated how HPV 16 oncoproteins E6 and E7 affect apoptosis in human laryngeal cancer cells. We established two human laryngeal cancer cell lines that expressed HPV 16 E6 and E7, respectively. Using these two cell lines, we found that both E6 and E7 exhibited an inhibitive effect on apoptosis induced by tumor necrosis factor alpha and cycloheximide. In both transfected cell lines, the expression of pro-apoptotic Bak was reduced and that of anti-apoptotic Bcl-2 was over-expressed. However, the expression of caspase-3 and caspase-8 was not significantly different between the E6- and E7-transfected cells and the control cells without HPV 16. p53 Protein was not detected in either the transfected or the non-transfected cells. Our study indicates that: (1) HPV 16 E6 and E7 oncoproteins are capable of inhibiting apoptosis in laryngeal squamous carcinoma cells; (2) the mechanism modulated by E6 and E7 involves the over-expression of Bcl-2 and the down-regulation of Bak; (3) the anti-apoptotic pathway is not related to the level of p53, caspase-3, or caspase-8. These results suggest that the dysregulation of apoptotic molecules Bak and Bcl-2 by HPV 16 E6 and E7 plays a role in the prolongation of cell survival, which may subsequently contribute to the development of human laryngeal cancer.

Animals↗
PubMed2004

Inhibitory effects of budesonide, desloratadine and dexamethasone on cytokine release from human mast cell line (HMC-1).

OBJECTIVE: To determine the inhibitory potency of budesonide on interleukin (IL)-4, 6 and 8, GM-CSF and TNF-alpha release from the human mast cell line (HMC-1) in comparison with the systemic glucocorticosteroid, dexamethasone, and H(1) antagonist, desloratadine. METHODS: HMC-1 was stimulated with 25 ng/ml phorbol 12- myristate 13-acetate (PMA) and 2.5 x 10(-7) M ionomycin (A23187) for 6, 12 and 24 h in both the presence and absence of 10(-6)-10(-10) M concentrations of the test drugs. Culture supernatants were collected and assayed by ELISAs. RESULTS: HMC-1 produced substantial amounts of GM-CSF and IL-8 and smaller amounts of TNF-alpha, IL-4 and IL-6 after being stimulated with PMA together with A23187. Budesonide and dexamethasone had potent inhibitory effects and desloratadine had modest inhibitory effects on the release of these cytokines. Budesonide was more potent than dexamethasone at most concentrations and time points. IL-4 was the cytokine which was most susceptible to inhibition by the three tested drugs. The inhibitory effects, in some cases, were time- and concentration-dependent. CONCLUSION: Budesonide had a potent inhibitory effect on cytokine release from HMC-1. Its potency was greater than that of both dexamethasone and desloratadine.

Budesonide↗
PubMed2003

Video sleep nasendoscopy: the Hong Kong experience.

Video sleep nasendoscopy is a valuable technique for the study of upper airway dynamics in obstructive sleep apnea syndrome. The authors' 10-year experience with its use in Hong Kong has allowed technique refinement for safety and optimal evaluation. Its use in the evaluation of patients who snore, patients with obstructive sleep apnea syndrome, and continuous positive airway pressure titration is presented.

Adult↗
PubMed2002

Cantonese tone perception ability of cochlear implant children in comparison with normal-hearing children.

BACKGROUND AND OBJECTIVE: Cantonese is a tone language. A change in the fundamental frequency pattern within the same phonemic segment causes a change in the lexical meaning. The present study examined the Cantonese tone perception ability of cochlear implant children in comparison with normal-hearing children. It was hypothesized that cochlear implant children follow a similar pattern of tone perception development, as do normal children. METHOD: 225 normal-hearing and 15 hearing-impaired children with cochlear implants were recruited. The high level (tone 1), high rising (tone 2) and low falling (tone 4) were the target tones examined. The three tones were arranged into tone pairs for identification. Each pair shared exactly the same segmental information but differed only in tones (e.g. /sy/ in tones 1 and 2 meaning 'book' and 'mouse', respectively). Subjects were required to point to the corresponding pictures after the live voice presentations. RESULTS: for each tone pair, each subject was awarded a score representing the proportion of stimuli pairs that were correctly discriminated by the subject. The average scores in the normal-hearing and hearing-impaired groups were 0.92 and 0.64, respectively. The normal group had the lowest average score in tone 2/tone 4 (0.87) while the hearing-impaired group performed the worst in tone 1/tone 2 (0.53) perception between the three tone contrasts. CONCLUSIONS: the normal-hearing group performed significantly better than the hearing-impaired group in basic Cantonese tone perception. The pattern of tone perception development of cochlear implant children did not seem to follow that of normal children. Contributing factors on the tone perception performance of the cochlear implant children were subject's age, duration of special training, and durations of wearing the hearing aid and the cochlear implant.

Audiometry, Pure-Tone↗
PubMed2001

A prospective study of foreign-body ingestion in 311 children.

OBJECTIVE: To determine the preferable management protocol of foreign body ingestion in pediatric patients. METHODS: All pediatric patients aged less than 12 years who presented with suspected foreign body ingestion in a hospital setting over a period of 3 years were prospectively studied. The usefulness of symptoms and various diagnostic procedures to identify the impacted foreign bodies were analyzed. RESULTS: Of 311 children aged 4 months to 12 years, 115 foreign bodies were encountered. The presentations in children aged younger than 5 years were markedly different from the older children, who behaved more like adults. All sharp foreign bodies (107 cases or 93%), mostly fish bones (90.4%), were found in the oropharynx under direct vision using either tongue depressor (57%), Macintosh laryngoscope (6%), indirect laryngeal mirror (2%) or transnasal flexible endoscopy (28%). Coins (eight cases or 7%) were the only foreign body impacted at or below the level of cricopharyngeus. A plain cervical X-ray has a low sensitivity (15.9%) and a high specificity (99.5%) in identifying the foreign bodies. CONCLUSIONS: As the majority of the foreign bodies were sharp bones and situated in the oropharynx, a management protocol involving examination with a tongue depressor, transnasal laryngoscope, selective lateral soft tissue neck X-ray, chest X-ray and watchful observation is usually adequate. Removal of these foreign bodies can be accomplished using a tongue depressor and Macintosh laryngoscope. Patients with a suspected coin ingestion have to be evaluated by X-ray, and a rigid pharyngo-oesophagoscopy should be the mainstay of treatment.

Age Distribution↗
PubMed2001

In vivo diagnosis of nasopharyngeal carcinoma using contact rhinoscopy.

OBJECTIVES: To evaluate the potential use of contact endoscopy for the diagnosis of nasopharyngeal carcinoma (NPC). STUDY DESIGN: Prospective study to examine the nasopharynx of 30 patients with nasopharyngeal carcinoma and 18 subjects with normal nasopharynx in a clinic setting using contact rhinoscopes (Karl Storz, Tuttlingen, Germany, 7215 AA, 00 and 7215 BA, 300; 23 cm long; 4 mm in diameter). METHODS: The superficial cells of the normal nasopharynx and the nasopharyngeal tumors were stained with 1% methylene blue and examined with contact rhinoscopes at high magnifications (x 60 and x 150). The areas under examination were then biopsied. The contact endoscopic images were compared with the corresponding hematoxylin and eosin-stained histologic sections of the biopsied tissues. RESULTS: Sixty-six procedures were performed in 48 patients. The images of normal pseudostratified ciliated epithelium and squamous epithelium were readily recognized by contact endoscopy in all subjects with normal nasopharynx (10 men and 8 women; mean age, 51.9 y). Twenty-six of 30 patients with NPC (86.6%; 18 men and 8 women; mean age, 50.6 y) were successfully examined by contact endoscopy under local anesthesia. In these 26 patients, two patterns of malignant cells were identified with contact endoscopy. The patterns of contact endoscopic images corresponded well with the histologic findings. CONCLUSION: Contact endoscopy is an accurate and reliable office-based procedure, which allows for in-vivo diagnosis of nasopharyngeal carcinoma.

Adult↗
PubMed2001

The 'double bag': a device for protection against blood spray in the management of epistaxis.

Nasal bleeding is one of the commonest emergencies that place medical staff at risk of blood contamination during management. A sizeable proportion of incidents have been reported where blood splashes in the facial area caused such contamination, and the exposed conjunctivae are potential sites for transmission of human immunodeficiency viruses (HIV). We present a simple self-made device named the 'Double Bag', which is highly effective in preventing blood spraying during the management of epistaxis. It was designed to be used while treating epistaxis or removing nasal packing after surgery, when transient bleeding is expected.

Blood-Borne Pathogens↗
PubMed2001

Management of ingested foreign bodies: a retrospective review of 5240 patients.

This review was carried out to assess the effectiveness of our protocol designed for the management of ingested foreign bodies. It was a retrospective review of 5240 patients with ingested foreign bodies admitted over a five-year period to the Ear Nose and Throat Unit. These patients were managed according to a standardized protocol which was adopted and modified from our previous study. Under his management protocol, the mean hospital stay was 1.6 days. Flexible oesophagoscopy under local anaesthesia, and rigid oesophagoscopy under general anaesthesia, were performed in 1.5 per cent and 7.7 per cent of cases respectively. Major complications including oesophageal perforation and deep neck abscesses occurred in 0.19 per cent of patients. There was no mortality. This management protocol for ingested foreign bodies was both safe and cost-effective when compared to similar studies reported in the literature.

Adolescent↗
PubMed2001

Variant Creutzfeldt-Jakob disease in Hong Kong.

A 34-year-old Chinese woman who had lived in the United Kingdom in the 1980s was admitted to hospital in Hong Kong because of a 7-month history of progressive neurological deterioration. Initially, she complained of heartburn and paraesthesia of the hands and feet. She then developed slowness of speech and gait, and was noted to be forgetful and irritable. In January 2001, she was brought back to Hong Kong for treatment. On admission in May she was dysarthric, ataxic, and dystonic. Magnetic resonance imaging showed high signals in both thalami suggestive of variant Creutzfeldt-Jakob disease. Other investigations, including electroencephalogram and lumbar puncture, were unremarkable. A tonsil biopsy showed the presence of prions. This patient's presentation is typical of the variant Creutzfeldt-Jakob disease cases that have been reported since 1996. Because of her residential history, we conclude that this is an imported case from the United Kingdom.

Adult↗