A new algorithm for determining collimator angles that favor efficiency in MLC based IMRT delivery

A new algorithm to determine collimator angles that favor delivery efficiency of intensity modulated radiotherapy plans was developed. It was found that the number of segments and monitor units (MUs) were largely reduced with the set of collimator angles determined with the new algorithm without compromising plan quality. The improvement of delivery efficiency using the new algorithm depends on the size and shape of the target(s), the number of modulation levels, and the type of leaf-sequencing algorithm. In a typical prostate case, when a sweeping leaf-sequencer is used for Varian 120 leaf (0.5 x 0.5 cm2 beamlet), 80 leaf (1 x 1 cm2 beamlet) and Elekta 40 leaf (1 x 1 cm2 beamlet), the number of segments was reduced by 42%, 29%, and 5%, respectively. The number of MUs was reduced by 41%, 35%, and 10%. For the Siemens MLC (IMFAST leaf sequencer, 1 x 1 cm2 beamlet) the segment reduction was 32% and the MU reduction was 14%. Comparison of the plans using the new and Brahme algorithms, in terms of target conformity index and dose volume histogram of the organs at risk, showed that the quality of the plans using the new algorithm was uncompromised. Similar results were obtained for a set of head and neck treatment plans.

The prevalence of dentine hypersensitivity in a hospital clinic population in Hong Kong

OBJECTIVES

Dentine hypersensitivity is a common clinical finding with a wide variation in prevalence values. The aim of this study was to establish the prevalence of dentine hypersensitivity and to examine some associated aetiological factors in a cross-sectional study of patients visiting the Periodontology and Oral Hygiene Clinic at Prince Phillip Dental Hospital, Hong Kong over a three-week period.

METHODS

226 patients were examined over a three-week period using a triple syringe to administer a blast of cold air to confirm the diagnosis of dentine hypersensitivity. Additional factors such as smoking habits, initiating stimuli, gingival recession and cervical tooth surface loss were noted.

RESULTS

153 patients were diagnosed as having dentine hypersensitivity, giving a prevalence figure of 67.7%. The commonest teeth affected were the lower incisors and the commonest initiating factor was cold drinks.

CONCLUSIONS

The prevalence of dentine hypersensitivity in a hospital periodontology clinic population in Hong Kong was 67.7%.

New strategies for the diagnosis and screening of malaria

Thin and thick blood film microscopy are the "gold standard" for malaria diagnosis. In recent years, there have been important developments in malaria diagnostic tests including fluorescence microscopy of malaria parasites stained with acridine orange, dipstick immunoassays that detect species-specific parasite antigens, and more recently, detection of parasite nucleic acids after amplification by PCR. With some of these methods, sensitivities and specificities approaching and even exceeding those of the thin and thick film can be attained. In particular, PCR-based tests for plasmodium DNA or RNA are more sensitive and specific than other tests for malarial parasites. A specific application for PCR diagnosis of malaria could be blood donor screening. Clinical trials of blood donor sreening for malarial parasites by PCR are being conducted, in which pooled donor samples are screened to increase efficiency and reduce costs. Some of the new diagnostic methods may have specific applications in particular settings, depending on the purpose and location of testing, and other factors such as cost, desired sensitivity and specificity, speed and ease of use.

Consensus statements from the Second International Lung Cancer Molecular Biomarkers Workshop: a European strategy for developing lung cancer molecular diagnostics in high risk populations

The Second Molecular Biomarkers Workshop was held at the Roy Castle International Centre for Lung Cancer Research in Liverpool, in June 2001 and it brought together experts in the clinical, epidemiological and molecular-pathology of lung cancer from Europe and the USA, to address issues surrounding the development of a European strategy for early lung cancer detection. The 2001 Workshop Breakout Groups concentrated on the current challenges in the early detection of lung cancer which need to be addressed in the light of the recent surge in interest in many countries for mounting new clinical trials to evaluate the utility of Spiral CT in early lung cancer detection. If population-based trials of CT screening are mounted it will also be a favorable clinical environment in which to evaluate efficiently recent advances in molecular screening and genotyping. The Workshop focused specifically on: a) clinical and molecular biomarkers, b) sputum as an early detection and diagnostic tool, c) validation of molecular markers prior to their use in early detection trials and d) ethical issues that have to be considered in early lung cancer detection trials. A distillation of the Workshop discussions is given in this article.

Nondestructive in situ thermoluminescence using CO(2) laser heating

We have obtained thermoluminescence glow curves nondestructively from large, solid, ceramic samples by laser spot heating. Although the samples are brittle, laser thermoluminescence glow curves could be obtained with no visible damage to the samples. The experimental glow curves match with theory. By contrast, conventional thermoluminescence measurements require small samples to be removed from a ceramic and placed in a thermoluminescence machine. Laser-induced thermoluminescence glow curves from LiF, silica, and porcelain are presented.

Non-coplanar inverse planning IMRT using the MIMiC system: clinical significance in choice of 2-cm/1-cm mode and single couch vs. multiple couch angles

The IMRT delivery process using MIMiC is extremely effective. In the hands of an experienced practitioner, MIMiC can provide excellent conformity to tumor volume with minimal damage to adjacent critical structures. However, the process is not completely automatic, even though it is an inverse planning process. The choice of machine treatment mode, 1- or 2-cm mode, and the choice of single couch angle vs. multiple, will yield quite different end results, with all prescription parameters being equal. The choice of mode and number of couch angles that yield excellent results of good coverage of the PTV with minimal hot spots and appropriate degree of normal tissue sparing still depends on the clinical experience of the planner. The size, shape, and total length of the PTV and those of the organs of interest dictate the choice. The authors demonstrated some clinical examples with comparative studies of the results of different choice of these parameters. In general, smaller beamlets with multiple couch angles give better PTV conformity, and critical organ avoidance. The down side of these choices are: (a) relatively more scattered hot spots within PTV, (b) longer time required to deliver the treatment, and (c) increased complexity of the process that could increase the chance of human error in treatment delivery.

A globin-coupled oxygen sensor from the facultatively alkaliphilic Bacillus halodurans C-125

We have recently discovered heme-containing signal transducers from the archaeon Halobacterium salinarum (HemAT-Hs) and the gram-positive bacterium Bacillus subtilis (HemAT-Bs). These proteins bind diatomic oxygen and trigger aerotactic responses. We identified that HemAT oxygen-sensing domains contain a globin-coupled sensor (GCS) motif, which exists as a two-domain transducer, having no similarity to the PAS domain (Period circadian protein, Ah receptor nuclear translocator protein, Single-minded protein) superfamily transducers. Using the GCS motif, we predicted that a 439-amino-acid protein annotated as a methyl-accepting chemotaxis protein (MCP) in the facultatively alkaliphilic bacterium Bacillus halodurans is a globin-coupled oxygen sensor. We cloned, expressed, and purified GCS(Bh), and performed its spectral analysis. GCS(Bh), binds heme and shows myoglobin-like spectra. This suggests that GCS(Bh) acts as an oxygen sensor and transmits a conformational signal through a linked signaling domain to trigger an aerotactic response in B. halodurans.

Review of recent advances in fluorescence bronchoscopy in early localization of central airway lung cancer

Centrally located lung cancers are radiologically occult until so far advanced as to have a low cure rate or require extensive resection for cure, but at a cost of high morbidity. These cancers represent about one-fifth of new lung cancers. Autofluorescence bronchoscopy appears to be an important tool in localizing premalignant and early malignant lesions in the large central airways, particularly when applied to high-risk patients. Applications include studies of molecular biology of premalignancy and early malignancy, chemoprevention studies, endobronchial therapy studies, localization of synchronous tumors, estimation of the extent of field cancerization, and better estimation of resection margins. Autofluorescence bronchoscopy appears to be significantly more sensitive than white light examination but has low specificity. This technology is likely to gain widespread use when evaluation of sputum for malignant changes is both more sensitive and specific, and when its application is demonstrated to reduce mortality in this important subgroup of non-small cell lung cancer patients.

A unitary patient record improves admission documentation in a medical assessment unit in a major teaching hospital

OBJECTIVE

To ascertain the impact of the introduction of a unitary patient record (UPR) on clerking documentation of emergency medical admissions.

DESIGN

Retrospective casenote audit.

SUBJECTS AND SETTING

Random sample of 100 unselected admissions to the medical assessment unit of a major teaching hospital, comprising two groups pre- and post-introduction of the UPR.

RESULTS

Statistically significant improvements in the documentation of several items were achieved; function before episode, ethnic origin, chest pain, breathlessness, ankle oedema, cough, bowel habit and locomotor symptoms and recording of blood pressure and peripheral pulses. There were trends towards improvement in other areas and there were no areas in which the UPR performed less well than standard documentation.

CONCLUSIONS

Introduction of the UPR represents the successful application of multidisciplinary principles to over 10,000 acute general medical admissions. It has improved some, but not all, aspects of documentation. Revision of the design of the UPR should lead to further progress, as part of an ongoing process of development and re-audit.

Isolation, culture, characterization and use of human renal tubular epithelial cells

Tubulointerstitial alterations are a hallmark of most renal diseases. In vitro culture of different cell types of the tubulointerstitial compartment have been instrumental in studying their respective contributions to the inflammatory and fibrotic process. The present paper provides an overview of the isolation, culture and characterization of tubular epithelial cells, with a main emphasis on cells from human origin.

5' CpG island methylation of the FHIT gene is correlated with loss of gene expression in lung and breast cancer

Allele loss and loss of expression of fragile histidine triad (FHIT), a putative tumor suppressor gene located in chromosome region 3p14.2, are frequent in several types of cancers. Tumor-acquired methylation of promoter region CpG islands is one method for silencing tumor suppressor genes. We investigated 5' CpG island methylation of the FHIT gene in 107 primary non-small cell lung cancer (NSCLC) samples and corresponding nonmalignant lung tissues, 39 primary breast carcinomas, as well as in 49 lung and 22 breast cancer cell lines by a methylation-specific PCR assay. In addition, we analyzed brushes from the bronchial epithelium of 35 heavy smokers without cancer. FHIT methylation was detected in 37% of primary NSCLCs, 31% of primary breast cancers, and 65% of lung and 86% of breast cancer cell lines. The frequency of methylation in small cell and NSCLC cell lines were identical. Methylation was found in 9% of the corresponding nonmalignant lung tissues and in 17% of bronchial brushes from heavy cigarette smokers. FHIT methylation was significantly correlated with loss of FHIT mRNA expression by Northern blot analysis in lung cancer cell lines and with loss of Fhit expression in NSCLC and breast tumors by immunostaining. We conclude that methylation of FHIT is a frequent event in NSCLC and breast cancers and is an important mechanism for loss of expression of this gene. Methylation of FHIT commences during lung cancer pathogenesis and may represent a marker for risk assessment.

Early detection for lung cancer. New tools for casefinding

OBJECTIVE

To review data from published population trials and clinical practice guidelines on screening for lung cancer to provide a recommendation for early detection of lung cancer.

QUALITY OF EVIDENCE

Literature was searched via MEDLINE using the MeSH headings "lung neoplasm," "mass screening," "thoracic radiography," and "sputum." Only prospective randomized controlled trials with large numbers of subjects were selected.

MAIN MESSAGE

Risk of lung cancer among long-term heavy smokers continues even years after stopping smoking. Risk is highest in smokers with chronic obstructive pulmonary disease. Canadian clinical practice guidelines currently recommend that sputum cytology examination and chest radiography (CXR) not be used for lung cancer screening. This guideline was deducted from four randomized population trials in the 1970s that have serious limitations and applies to asymptomatic adults only. A CXR and sputum cytology examination are indicated in symptomatic current and former smokers older than 45 years with a smoking history of 30 pack-years or more and airflow obstruction defined as a forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) of 70% or less and a FEV1 lower than 70%. Curative treatment is available for early lung cancer. Substantial advances in innovative technologies for early detection using low-dose spiral CT and newer sputum tests have been made in the last three decades. Additional studies are under way to evaluate these new technologies.

CONCLUSION

Primary care physicians have an important role in identifying people at risk of developing lung cancer and in supporting research to evaluate new screening technology.

Protective role of cyclooxygenase inhibitors in the adverse action of passive cigarette smoking on the initiation of experimental colitis in rats

Clinical and experimental findings had indicated that cigarette smoke exposure, and cyclooxygenase-2, are strongly associated with inflammatory bowel disease. The present study aimed to evaluate the role of cyclooxygenase-2 in the pathogenesis of experimental inflammatory bowel disease as well as in the adverse action of cigarette-smoke exposure. Rats were pretreated with different cyclooxygenase-2 inhibitors (indomethacin, nimesulide, or SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide)) along with cigarette-smoke exposure before 2,4,6-trinitrobenzenesulfonic acid-enema. Results indicated that pretreatment with cyclooxygenase-2 inhibitors not only protected against 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also attenuated the potentiating effect of cigarette-smoke exposure on colonic damage. Furthermore, the colonic cyclooxygenase-2 protein and mRNA expression was markedly induced by 2,4,6-trinitrobenzenesulfonic acid-enema, and it was potentiated further by cigarette-smoke exposure, while the cyclooxygenase-1 expression was not changed. The present study suggests that the highly induced cyclooxygenase-2 expression not only plays a pathogenic role in 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also contributes to the adverse action of cigarette-smoke exposure on this disorder.

Cultural expectations of thinness in Chinese women

The present study examined the ideal woman's figure among Chinese people in Hong Kong over the past three decades by analyzing the data from the Miss Hong Kong Beauty Pageant from 1975-2000. Results indicate that Miss Hong Kong Pageant winners and Miss Photogenic winners have always been taller and thinner than average women in Hong Kong. The data also suggest that a curvaceous body shape with a narrow waist set against full hips appears to be an important component of feminine beauty among the Chinese. This ideal matches closely to what has been depicted in classical Chinese literature and challenges the commonly held belief that Chinese feminine beauty standards value plumpness.

Detection and localization of early lung cancer by fluorescence bronchoscopy

BACKGROUND

Curative therapy is available for patients with Stage 0 lung carcinoma, with a >90% 5-year survival rate. Promising chemopreventive agents also are under investigation currently to reduce the risk of lung carcinoma in high risk populations. However, preinvasive bronchial lesions (moderate to severe dysplasia and carcinoma in situ) are very small and thin. They are difficult to localize by conventional white-light bronchoscopy. Fluorescence bronchoscopy is a new diagnostic tool for the detection of these preinvasive lesions.

METHODS

The data on the use of fluorescence bronchoscopy to detect and localize preinvasive lesions in current heavy smokers and in former smokers at the British Columbia Cancer Agency as well as the worldwide experience cited in MEDLINE, Index Medicus, and Deutsches Institut fur Medizinische Dokumentation und Information (Cologne, Germany) comparing white-light and fluorescence bronchoscopy using the lung imaging fluorescence endoscope (LIFE)-Lung device (Xillix Technologies Corp., Richmond, British Columbia, Canada) were reviewed.

RESULTS

Among current heavy smokers and former smokers with sputum atypia, the prevalence of carcinoma in situ was 1.6%. Moderate or severe dysplasia was found in another 19%. The preinvasive lesions were found to be small: 55% measured < or = 1.5 mm in greatest dimension. Over 1000 cases have been reported in the literature between 1994 and 1999. Overall, 40% of the preinvasive lesions were detected by white-light bronchoscopy alone. The addition of fluorescence bronchoscopy increased the detection rate to an average of 80%.

CONCLUSIONS

Preinvasive lesions, especially dysplastic lesions, are small. They are difficult to detect and localize by white-light bronchoscopy. Fluorescence bronchoscopy improves the detection rate. It is an important part of the armamentarium in the overall management of early lung cancer.

Intranuclear huntingtin increases the expression of caspase-1 and induces apoptosis

Expansion of a polyglutamine repeat in huntingtin causes Huntington's disease (HD). Although full-length huntingtin is predominantly distributed in the cytoplasm, N-terminal fragments of huntingtin with expanded polyglutamine tracts are able to accumulate in the nucleus and kill neurons through apoptotic pathways. Transgenic mice expressing N-terminal mutant huntingtin show intranuclear huntingtin accumulation and develop progressive neurological symptoms. Inhibiting caspase-1 can prolong the survival of these HD mice. How intranuclear huntingtin is associated with caspase activation and apoptosis is unclear. Here we report that intranuclear huntingtin induces the activation of caspase-3 and the release of cytochrome c from mitochondria in cultured cells. As a result, cells expressing intranuclear huntingtin undergo apoptosis. We show that intranuclear huntingtin increases the expression of caspase-1, which may in turn activate caspase-3 and trigger apoptosis. We propose that the increased level of caspase-1 induced by intranuclear huntingtin contributes to HD-associated cell death.

Combination therapy with lamivudine and famciclovir for chronic hepatitis B-infected Chinese patients: a viral dynamics study

In vitro studies have shown that lamivudine and penciclovir (the active metabolite of famciclovir) act synergistically to inhibit hepatitis B virus (HBV) replication. We compared the effectiveness of HBV viral suppression by lamivudine monotherapy versus lamivudine plus famciclovir combination therapy in Chinese patients with chronic HBV infection. Twenty-one Chinese hepatitis B e antigen (HBeAg)-positive patients, with detectable HBV DNA (Digene Hybrid Capture II), were randomized to receive either lamivudine 150 mg/d orally (group 1, 9 patients) or lamivudine 150 mg/d plus famciclovir 500 mg 3 times a day orally (group 2, 12 patients) for 12 weeks, with a follow-up period of at least 16 weeks. Serial serum HBV-DNA levels were determined and a mathematical model with provision for incomplete inhibition of virus production during therapy was applied to analyze the dynamics of viral clearance. The mean antiviral efficacy was significantly greater in group 2 than in group 1 (0.988 +/- 0.012 vs. 0.94 +/- 0.03, P =.0012). HBV DNA returned to pretreatment level within 16 weeks after the end of initial treatment in 4 patients (66.7%) in group 1 and none in group 2 (P =.08), who remained HBeAg positive and received no further treatment after week 12. Hence, in Chinese chronic HBeAg-positive patients, combination therapy using lamivudine and famciclovir was superior to lamivudine monotherapy in inhibiting HBV replication. Further studies of longer duration are needed to define whether combination therapy will increase the HBeAg seroconversion rate and decrease the rate of emergence of lamivudine-resistant variants.