Effects of Lugol's iodine solution and formalin on cell volume of three bloom-forming dinoflagellates

Fixatives are traditionally used in marine ecosystem research. The bias introduced by fixatives on.the dimensions of plankton cells may lead to an overestimation or underestimation of the carbon biomass. To determine the impact of traditional fixatives on dinoflagellates during short- and long-term fixation, we analyzed the degree of change in three bloom-forming dinoflagellates （Prorocentrum rnicans, Scrippsiella trochoidea and Nocfiluca scintillans） brought about by Lugol＇s iodine solution （hereafter Lugol＇s） and formalin. The fixation effects were species-specific. P. micans cell volume showed no significant change following long-term preservation, and S. trochoidea swelled by approximately 8.06% in Lugol＇s and by 20.97% in formalin as a percentage of the live cell volume, respectively. N. scintillans shrank significantly in both fixatives. The volume change due to formalin in N. scintillans was not concentration-dependent, whereas the volume shrinkage ofN. scintillans cells fixed with Lugol＇s at a concentration of 2% was nearly six-fold that in cells fixed with Lugol＇s at a concentration of 0.6%-0.8%. To better estimate the volume of N. scintillans fixed in formalin at a concentration of 5%, we suggest that the conversion relationship was as follows： volume of live cell=volume of intact fixed cell/0.61. Apart from size change, damage induced by fixatives on N. scintillans was obvious. Lugol＇s is not a suitable fixative for N. scintillans due to high frequency of broken cells. Accurate carbon biomass estimate ofN. scintillans should be performed on live samples. These findings help to improve the estimate of phytoplankton cell volume and carbon biomass in marine ecosystem.

Narrow-band imaging without magnification for detecting early esophageal squamous cell carcinoma

AIM：To compare narrow-band imaging（NBI）without image magnification,and chromoendoscopy with Lugol＇s solution for detecting high-grade dysplasia and intramu-cosal esophageal squamous cell carcinoma（SCC）in patients with head and neck cancer.METHODS：This was a prospective observational study of 129 patients with primary head and neck tumors consecutively referred to the Gastrointestinal Endoscopy Unit of Hospital das Clínicas,Sao Paulo University Medical School,Brazil,between August 2006 and Feb-ruary 2007.Conventional examinations with NBI and Lugol chromoendoscopy were consecutively performed,and the discovered lesions were mapped,recorded and sent for biopsy.The results of the three methods were compared regarding sensitivity,specificity,accuracy,positive predictive value,negative predictive value,positive likelihood value and negative likelihood value.RESULTS：Of the 129 patients,nine（7%）were diag-nosed with SCC,5 of which were in situ and 4 which were intramucosal.All carcinomas were detected through NBI and Lugol chromoendoscopy.Only 4 le-sions were diagnosed through conventional examination,all of which were larger than 10 mm.CONCLUSION：NBI technology with optical filters has high sensitivity and high negative predictive value for detecting superficial esophageal SCC,and produces results comparable to those obtained with 2.5%Lugol chromoendoscopy.

Chibuike O Chigbu, MD, Series EditorTrends in cervical cancer screening in developing countries

Developing countries suffer the highest burden of cervical cancers but have the lowest resources. Effective cervical cytology screening programme, along with a network of diagnostic and therapeutic colposcopy centres, like developed countries, is almost impossible to be reproduced in developing countries. Visual inspection methods [e.g., Visual inspection with Lugol's iodine(VILI) and Visual Inspection with Acetic Acid(VIA)] which are cheaper, require less expertise and have the advantage of possible treatment in one setting have been shown to be effective alternatives. The sensitivity to detect CIN2+, by VIA and VILI, have been shown to be 80% and 91% respectively, with a specificity rate of 92% and 85% respectively. Screening by human papillomavirus(HPV) testing has high sensitivity(96.4%) but low specificity(94.1%) to detect CIN2+, when compared to Pap Smear(sensitivity, 55.4% and specificity, 96.8%). A single lifetime HPV testing in a large unscreened population has been shown to significantlyreduce cervical cancer incidence and mortality when compared to cervical cytology, VIA or no screening. HPV testing of self-collected vaginal specimens also helps to overcome religious and socio-cultural barriers towards pelvic examination amongst women in developing countries. Current HPV testing methods are expensive, skill/infrastructure demanding and takes time to produce results. A cheaper HPV test, called careH PV?, which is able to provide results within 2.5 h and requires minimal skill/infrastructure to operate, was designed for use in developing countries. One stop screen and treat facilities using VIA or rapid HPV testing, and cryotherapy, can overcome non-compliance to follow-up which is a major issue in developing countries. Cure rates of 81.4% for CIN1, 71.4% for CIN2 and 68.0% for CIN3 at 6 mo after treatment have been reported. Incorporating telemedicine with cervicography of VIA or VILI or even telecolposcopy, has great potential in cervical cancer screening, especially in countries with vast geographical areas.