A novel lysine-rich domain and GTP binding motifs regulate the nucleolar retention of human guanine nucleotide binding protein, GNL3L

A variety of G-proteins and GTPases are known to be involved in nucleolar function. We describe here a new evolutionarily conserved putative human GTPase, guanine nucleotide binding protein-like 3-like (GNL3L). Genes encoding proteins related to GNL3L are present in bacteria and yeast to metazoa and suggests its critical role in development. Conserved domain search analysis revealed that the GNL3L contains a circularly permuted G-motif described by a G5-G4-G1-G2-G3 pattern similar to the HSR1/MMR1 GTP-binding protein subfamily. Highly conserved and critical residues were identified from a three-dimensional structural model obtained for GNL3L using the crystal structure of an Ylqf GTPase from Bacillus subtilis. We demonstrate here that GNL3L is transported into the nucleolus by a novel lysine-rich nucleolar localization signal (NoLS) residing within 1-50 amino acid residues. NoLS identified here is necessary and sufficient to target the heterologous proteins to the nucleolus. We show for the first time that the lysine-rich targeting signal interacts with the nuclear transport receptor, importin-beta and transports GNL3L into the nucleolus. Interestingly, depletion of intracellular GTP blocks GNL3L accumulation into the nucleolar compartment. Furthermore, mutations within the G-domains alter the GTP binding ability of GNL3L and abrogate wild-type nucleolar retention even in the presence of functional NoLS, suggesting that the efficient nucleolar retention of GNL3L involves activities of both basic NoLS and GTP-binding domains. Collectively, these data suggest that GNL3L is composed of distinct modules, each of which plays a specific role in molecular interactions for its nucleolar retention and subsequent function(s) within the nucleolus.

A new relaxed state in horse methemoglobin characterized by crystallographic studies

A new relaxed state has been characterized in the crystals of horse methemoglobin grown at neutral pH at low ionic concentration and their low humidity variants. The crystals provide an example for improvement in X-ray diffraction quality with reduced solvent content. Only the classical R state has been so far observed in liganded horse hemoglobin. The state characterized in the present study lies in between the R state and the R2 state characterized earlier in liganded human hemoglobin. The results presented here, along with those of earlier studies, suggest that relaxed and tense hemoglobin can access ensembles of states.

Association between diabetes mellitus and pre-malignant oral diseases: A cross sectional study in Kerala, India

Recent studies have suggested role of diabetes mellitus in the development of periodontal diseases, oral inflammatory and neoplastic lesions. We analysed data from randomised oral cancer screening trial in Kerala, India, to study the association between chronic diseases in general, diabetes mellitus in particular, and pre-malignant oral lesions and conditions. A total of 927 subjects with oral leukoplakia, 170 with oral submucous fibrosis, 100 with erythroplakia lesions and 47,773 apparently healthy subjects constituted the cases and controls respectively for our present study. The odds ratio (OR) for oral leukoplakia among women with a history of diabetes mellitus was found to be 2.0 (95% confidence interval (CI) = 1.4-2.9) whereas that for erythroplakia was 3.2 (95% CI = 1.3-7.9), after adjusting for potential confounders. No statistically significant association between diabetes mellitus and oral submucous fibrosis and pre-cancerous lesions/conditions in men was found. An association between diabetes mellitus and pre-malignant oral lesions among women has been observed in our study, although the underlying mechanisms are not clear. This needs to be further evaluated in other settings.

Worldwide burden of gynaecological cancer: the size of the problem

The estimation of cancer burden is valuable to set up priorities for disease control. The comprehensive global cancer statistics from the International Agency for Research on Cancer indicate that gynaecological cancers accounted for 19% of the 5.1 million estimated new cancer cases, 2.9 million cancer deaths and 13 million 5-year prevalent cancer cases among women in the world in 2002. Cervical cancer accounted for 493 000 new cases and 273 000 deaths; uterine body cancer for 199 000 new cases and 50 000 deaths; ovarian cancer for 204 000 new cases and 125 000 deaths; cancers of the vagina, vulva and choriocarcinoma together constituted 45 900 cases. More than 80% of the cervical cancer cases occurred in developing countries and two-thirds of corpus uteri cases occurred in the developed world. Political will and advocacy to invest in healthcare infrastructure and human resources to improve service delivery and accessibility are vital to reduce the current burden in low- and medium-resource countries.

Tobacco associated mortality in Mumbai (Bombay) India. Results of the Bombay Cohort Study

BACKGROUND

Little is known about the excess mortality from forms of tobacco use other than cigarette smoking that are widely prevalent in India, such as bidi smoking and the various forms of smokeless tobacco use. We report on absolute and relative risks of mortality among various kinds of ever tobacco users vs never-users in the city of Mumbai, India.

METHODS

Using the Mumbai voters' list as the selection frame, 99 570 individuals aged > or = 35 years were interviewed at their homes during 1992-94. At active follow-up (during 1997-99) after 5.5 years, 97 244 (97.7%) were traced. Among these, 7531 deaths (4119 men, 3412 women) were recorded, of which 89% died within study area. It was possible to abstract cause of death information from the records of the municipal corporation for 5470 deaths. These were coded using ICD 10.

RESULTS

The adjusted relative risk was 1.37 (95% CI 1.23-1.53) for (men) cigarette smokers and 1.64 (95% CI 1.47-1.81) for bidi smokers, with a significant dose-response relationship for number of bidis or cigarettes smoked. Women were essentially smokeless tobacco users; the adjusted relative risk was 1.25 (95% CI 1.15-1.35). The risk of deaths from respiratory diseases (RR 2.12, 95% CI 1.57-2.87), tuberculosis (RR 2.30, 95% CI 1.68-3.15), and neoplasms (RR 2.60, 95% CI 1.78-3.80) were significantly high in male smokers than never tobacco users.

CONCLUSIONS

Bidi is no less hazardous than cigarette smoking, and smokeless tobacco use may also result in significantly increased mortality.

A critical assessment of screening methods for cervical neoplasia

The objective of cervical cancer screening is to reduce cervical cancer incidence and mortality by detecting and treating precancerous lesions. Conventional cytology is the most widely used cervical cancer screening test. Although cytology has been effective in reducing the incidence of and mortality from cervical cancer in developed countries in both opportunistic and--more dramatically--organized national programs, it has been less successful and largely ineffective in reducing disease burden in low-resource settings where it has been implemented. Liquid-based cytology, testing for infection with oncogenic types of human papillomaviruses, visual inspection with 3-5% acetic acid, magnified visual inspection with acetic acid, and visual inspection with Lugol's iodine have been evaluated as alternative tests. Their test characteristics, and the applications and limitations in screening, are discussed with an emphasis on the work of the Alliance for Cervical Cancer Prevention over the past 5 years.

Major histocompatibility complex class I polymorphism in Asiatic lions

Asiatic lions (Panthera leo persica), whose only natural habitat in the world is the Gir forest sanctuary of Gujarat State in India, are highly endangered and are considered to be highly inbred with narrow genetic diversity. An objective assessment of genetic diversity in their immune loci will help in assessing their survivability and may provide vital clues in designing strategies for their scientific management and conservation. We analyzed the comparative sequence polymorphism at exon 2 and exon 3 of major histocompatibility complex (MHC) class I in three groups of lions, i.e. wild Asiatic (from Gir forest), captive-bred Asiatic (from zoological parks in India), and Afro-Asiatic hybrid groups (from zoological parks in India) through polymorphism chain reaction-assisted sequence-based typing. The two exons were amplified, cloned, sequenced, and analyzed for polymorphism at nucleotide and putative translated product level. The analysis revealed extensive sequence polymorphism not only between clones derived from different lions but also the clones derived from a single lion. Furthermore, the wild Asiatic lions of Gir forest exhibited abundant sequence polymorphism at MHC class I comparable with that of Afro-Asiatic hybrid lions and significantly higher than that of captive-bred Asiatic lions. We hypothesize that Asiatic lions of Gir forest are not highly inbred as thought earlier and they possess abundant sequence polymorphism at MHC class I loci. During this study, 52 new sequences of the multigene MHC class I family were also identified among Asiatic lions.

Papillomavirus infection in rural women in southern India

To investigate the prevalence of, and the risk factors for, cervical infection with 44 types of human papillomavirus (HPV) in a rural area in the Dindigul District, Tamil Nadu, India, we interviewed and obtained cervical cell samples from 1891 married women aged 16-59 years. HPV prevalence was 16.9% overall and 14.0% among women without cervical abnormalities, or 17.7 and 15.2%, respectively, age-standardised to the world standard population. In all, 21.9% of infections involved more than one HPV type. High-risk HPV types predominated, particularly HPV 16 (22.5% of women infected), followed by HPV 56, HPV 31, HPV 33 and HPV 18. Unlike most populations studied in developed countries, HPV prevalence was constant across the age groups. HPV positivity was inversely associated with education level (odds ratio (OR) among women with high school vs no education=0.6) and positively associated with widowhood and divorce (OR=1.7), nulligravidity (OR=2.3), and condom use (OR=2.6). It is unclear how much low clearance of, or frequent reinfection with HPV accounted for the study prevalence of infection in different age groups.

Training for cervical cancer prevention programs in low-resource settings: Focus on visual inspection with acetic acid and cryotherapy

The modern approach to cervical cancer prevention, characterized by use of cytology and multiple visits for diagnosis and treatment, has frequently proven challenging and unworkable in low-resource settings. Because of this, the Alliance for Cervical Cancer Prevention (ACCP) has made it a priority to investigate and assess alternative approaches, particularly the use of visual screening methods, such as visual inspection with acetic acid (VIA) and visual inspection with Lugol's iodine (VILI), for precancer and cancer detection and the use of cryotherapy as a precancer treatment method. As a result of ACCP experience in providing training to nurses and doctors in these techniques, it is now widely agreed that training should be competency based, combining both didactic and hands-on approaches, and should be done in a clinical setting that resembles the service-delivery conditions at the program site. This article reviews ACCP experiences and perceptions about the essentials of training in visual inspection and cryotherapy and presents some lessons learned with regard to training in these techniques in low-resource settings.

Concurrent evaluation of visual, cytological and HPV testing as screening methods for the early detection of cervical neoplasia in Mumbai, India

OBJECTIVE

Naked eye visual inspection with acetic acid (VIA), magnified VIA (VIAM), visual inspection with Lugol's iodine (VILI), cytology and human papillomavirus (HPV) testing were evaluated as screening methods for the detection of high-grade squamous intraepithelial lesions (HSIL) of the uterine cervix in a cross-sectional study in Mumbai, India.

METHODS

Cytology, HPV testing, VIA, VIAM and VILI were carried out concurrently for 4039 women aged 30-65 years. All women were investigated with colposcopy and biopsies were taken from 939 women who had colposcopic abnormalities. The reference standard for final disease status was histology or negative colposcopy. The presence of HSIL was confirmed in 57 women (1.4%). The test characteristics for each method were calculated using standard formulae.

RESULTS

The sensitivities of cytology, HPV testing, VIA, VIAM and VILI were 57.4%, 62.0%, 59.7%, 64.9%, and 75.4%, respectively (differences were not statistically significant). The specificities were 98.6%, 93.5%, 88.4%, 86.3%, and 84.3%, respectively. Adding a visual test to cytology or HPV testing in parallel combination resulted in a substantial increase in sensitivity, with a moderate decrease in specificity. The parallel combination of VILI and HPV testing resulted in a sensitivity of 92.0% and a specificity of 79.9%.

CONCLUSION

As a single test, cytology had the best balance of sensitivity and specificity. Visual tests are promising in low-resource settings, such as India. The use of both VIA and VILI may be considered where good quality cytology or HPV testing are not feasible. The sensitivity of cytology and HPV testing increased significantly when combined with VIA or VILI.

Survival from oral cancer in Mumbai (Bombay), India

OBJECTIVE

Cancer survival information is available for only few populations in developing countries. Data on survival of oral cancer patients registered by the Bombay population-based cancer registry, India, during 1992-1994 is presented in this paper.

METHODS

Vital status of the patients was established by matching against death certificates, reply paid postal enquiries, telephone enquiries, scrutiny of hospital records and house visits. Of the 1808 eligible cases for analysis, 1204 (66.6%) were dead; and 604 (33.4%) were alive at last follow-up, of whom 136 were lost to follow-up during the first 5-years after diagnosis. Observed and relative survival rates are presented and hazard ratios and corresponding 95% confidence intervals were estimated using Cox proportional hazard model.

RESULTS

The overall 5-year observed and relative survival rates were 30.5% and 39.7%, respectively. Survival steadily declined with advancing age and advanced clinical stages. Five-year observed survival was 59.1% for localised cancer, 15.7% for cancers with regional extension and 1.6% for those with distant metastasis. Those with tongue, buccal mucosa and retromolar trigone cancers had poor survival rates.

CONCLUSIONS

Our study shows that detecting oral cancer in early stages, when these are amenable to single modality therapies, offers the best chance of long-term survival. However, primary prevention by tobacco/alcohol control measures is important in the long-term perspective.

Survival from glottic and supraglottic laryngeal carcinoma in Mumbai (Bombay), India

The survival experience of patients with cancer of the larynx (ICD 10) registered by the Bombay population-based cancer registry India, during the years 1992-1994, is described. The vital status of these subjects were established by matching with death certificates from the Bombay Municipal death register and by active methods such as reply-paid postal enquiries, telephone enquiries, scrutiny of case records and house visits. Of the 675 eligible cases for analysis, 458 (67.9%) were dead and 217 (32.1%) were alive at last follow-up. The 5-year observed and relative survival rates were 29.1 and 38.2%, respectively; these were 52.1 and 58.5% for glottic laryngeal cancer and 24.2 and 31.4% for supraglottic laryngeal cancer, respectively. The 5-year observed survival was 53.1% for those with localised cancer and 17.8% for those with regional extension. Advancing age, regional and metastatic disease and supraglottic cancers were associated with significantly reduced survival. Early detection and prompt treatment should improve overall survival from laryngeal cancer.

Socioeconomic status, lifestyle factors and oral premalignant lesions

Several studies have suggested that low socioeconomic status (SES) is associated with a higher risk of oral cancer, but the association with oral premalignant lesions has not yet been explored. The aim of this study was to examine the association of education, occupation, income and SES index with oral premalignant lesions. A case-control study was conducted with data from the baseline screening of a randomized oral cancer screening trial in Kerala, India. There were a total of 927 oral leukoplakia, 170 oral submucous fibrosis, 100 erythroplakia and 115 multiple oral premalignant lesion cases and 47,773 controls. Subjects with high SES index had protective ORs for oral premalignant lesions, ranging from 0.6 to 0.7, after adjustment for age, sex, BMI, tobacco chewing, smoking, drinking and fruit/vegetable intake. Higher education levels were also associated with decreased risk of all four oral premalignant lesions. Protective ORs for income were observed for oral leukoplakia and possibly oral submucous fibrosis and erythroplakia. SES may be associated with oral premalignant lesions because of access to medical care, health related behaviors, living environment or psychosocial factors. Though the mechanism for the association is not clear, higher SES index, education and income were associated with decreased risk of oral premalignant lesions in our study.

Interim results from a cluster randomized controlled oral cancer screening trial in Kerala, India

A cluster randomized controlled oral cancer screening trial is on-going in the Trivandrum district, India, to evaluate the efficacy of screening in reducing oral cancer mortality. Subjects, aged 35 years and above, in 13 clusters in the Trivandrum district, India, were randomized to the intervention (screening) group (7 clusters, 78969 subjects) to receive three rounds of screening by oral visual inspection by trained health workers at 3-year intervals or to a control group (6 clusters, 74739 subjects). Two rounds of screening were completed between 1995 and 2002 during which 69896 (88.5%) subjects were screened at least once, and 59.7% of the 4408 screen-positive subjects were further investigated. In the intervention group, 344404 person-years were accrued and 329326 person-years were in the control group. In the intervention group, 149 incident oral cancer cases and 65 deaths from oral cancer were observed, and 106 incident cases and 62 deaths from oral cancer were observed in the control group. The programme sensitivity for detection of oral precancerous lesions and cancer was 81.5% and the programme specificity was 84.8%; the programme positive predictive value was 39.6%. In the intervention group 37.6% of the cases were in stages I-II, as opposed to 18.9% in the control group. The 3 year survival rate was 57.5% in the intervention and 38.8% in the control group (P<0.05). The age standardized oral cancer mortality rates were 21.2/100000 person-years in the intervention and 21.3/100000 in the control group. After completing two rounds of screening, oral cancer mortality rates were similar in both study groups.

Visual inspection with acetic acid and cytology in the early detection of cervical neoplasia in Kolkata, India

Visual inspection of the cervix after application of 3-5% acetic acid (VIA) is a potential alternative to cytology for screening in low-resource countries. The present study evaluated the performance of VIA, magnified visual inspection after application of acetic acid (VIAM), and cytology in the detection of high-grade cervical cancer precursor lesions in Kolkata (Calcutta) and suburbs in eastern India. Trained health workers with college education concurrently screened 5881 women aged 30-64 years with VIA, VIAM, and conventional cervical cytology. Detection of well-defined, opaque acetowhite lesions close to the squamocolumnar junction; well-defined, circumorificial acetowhite lesions; or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA or VIAM. Cytology was considered positive if reported as mild dysplasia or worse lesions. All screened women (N = 5881) were evaluated by colposcopy, and biopsies were directed in those with colposcopic abnormalities (N = 1052, 17.9%). The final diagnosis was based on histology (if biopsies had been taken) or colposcopic findings, which allowed direct estimation of sensitivity, specificity, and predictive values. Moderate or severe dysplasia or carcinoma in situ (CIN 2-3 disease) was considered as true positive disease for the calculation of sensitivity, specificity, and predictive values of screening tests. 18.7%, 17.7% and 8.2% of the women tested positive for VIA, VIAM, and cytology. One hundred twenty two women had a final diagnosis of CIN 2-3 lesions. The sensitivities of VIA and VIAM to detect CIN 2-3 lesions were 55.7% and 60.7%, respectively; the specificities were 82.1% and 83.2%, respectively. The sensitivity and specificity of cytology were 29.5% and 92.3%, respectively. All the tests were associated with negative predictive values above 98%. VIA and VIAM had significantly higher sensitivity than cytology in our study; the specificity of cytology was higher than that of VIA and VIAM.

Recurrence of fidelity in nearly integrable systems

Within the framework of simple perturbation theory, recurrence time of quantum fidelity is related to the period of the classical motion. This indicates the possibility of recurrence in nearly integrable systems. We have studied such possibility in detail with the kicked rotor as an example. In accordance with the correspondence principle, recurrence is observed when the underlying classical dynamics is well approximated by the harmonic oscillator. Quantum revival of fidelity is noted in the interior of resonances, while classical-quantum correspondence of fidelity is seen to be very short for states initially in the rotational Kolmogorov-Arnold-Moser region.

Visual inspection with acetic acid and cytology in the early detection of cervical neoplasia in Kolkata, India

Visual inspection of the cervix after application of 3–5% acetic acid (VIA) is a potential alternative to cytology for screening in low-resource countries. The present study evaluated the performance of VIA, magnified visual inspection after application of acetic acid (VIAM), and cytology in the detection of high-grade cervical cancer precursor lesions in Kolkata (Calcutta) and suburbs in eastern India. Trained health workers with college education concurrently screened 5881 women aged 30–64 years with VIA, VIAM, and conventional cervical cytology. Detection of well-defined, opaque acetowhite lesions close to the squamocolumnar junction; well-defined, circumorificial acetowhite lesions; or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA or VIAM. Cytology was considered positive if reported as mild dysplasia or worse lesions. All screened women (N = 5881) were evaluated by colposcopy, and biopsies were directed in those with colposcopic abnormalities (N = 1052, 17.9%). The final diagnosis was based on histology (if biopsies had been taken) or colposcopic findings, which allowed direct estimation of sensitivity, specificity, and predictive values. Moderate or severe dysplasia or carcinoma in situ (CIN 2–3 disease) was considered as true positive disease for the calculation of sensitivity, specificity, and predictive values of screening tests. 18.7%, 17.7% and 8.2% of the women tested positive for VIA, VIAM, and cytology. One hundred twenty two women had a final diagnosis of CIN 2–3 lesions. The sensitivities of VIA and VIAM to detect CIN 2–3 lesions were 55.7% and 60.7%, respectively; the specificities were 82.1% and 83.2%, respectively. The sensitivity and specificity of cytology were 29.5% and 92.3%, respectively. All the tests were associated with negative predictive values above 98%. VIA and VIAM had significantly higher sensitivity than cytology in our study; the specificity of cytology was higher than that of VIA and VIAM.

Pseudohypoparathyroidism with systemic lupus erythematosus

A female patient with short stature, of systemic lupus erythematosis and hypocalcemia presented to us. On examination and investigations she was found to be a case of Type Ia pseudohypoparathyroidism. The patient's quality of life improved after appropriate treatment. The case is a rare combination of two disorders.

Do younger female breast cancer patients have a poorer prognosis? Results from a population-based survival analysis

Younger women who develop breast cancer are hypothesized to have poorer survival rates than women who develop it at a later stage in life. Several studies have suggested that differences in biologic characteristics of breast cancer in younger (premenopausal) and older (postmenopausal) women may account for the prognostic variation. This population-based cohort study reports on survival rates of breast cancer in Singapore and examines the hypothesis that younger breast cancer patients have a poorer prognosis. A total of 6,397 breast cancer patients diagnosed from 1968 to 1992 were identified from the population-based cancer registry and followed up through 1997. Outcome measures were relative survival rates (RSRs) calculated using Hakulinen's method and excess hazards ratios (HRs) derived from a regression model based on relative survival. The 2-, 5- and 10-year RSRs were worse among those aged > 75 (65%, 48% and 39%, respectively). The best survival rates were seen among those aged 40-44 (84%, 67% and 56%). Patients younger than 35 years faired reasonably well (79%, 60% and 50%). When the data were stratified according to clinical stage and calendar year, the highest risk of excess deaths was found in women > or = 75 years old. In patients with localized cancer and/or regional metastases, those in the 35-39 age group had the lowest excess risk. In patients with distant metastases, those younger than 35 years of age had the lowest excess risk of death. At the population level, younger women (< 45 years) with breast cancer in Singapore have higher relative survival rates.

Early detection of cervical cancer with visual inspection methods: a summary of completed and on-going studies in India

India is a high-risk country for cervical cancer which accounts a quarter (126,000 new cases, 71,000 deaths around 2,000) of the world burden. The age-standardized incidence rates range from 16-55 per 100,000 women in different regions with particularly high rates in rural areas. Control of cervical cancer by early detection and treatment is a priority of the National Cancer Control Programme of India. There are no organized cytology screening programmes in the country. The technical and financial constraints to organize cytology screening have encouraged the evaluation of visual inspection approaches as potential alternatives to cervical cytology in India. Four types of visual detection approaches for cervical neoplasia are investigated in India: a) naked eye inspection without acetic acid application, widely known as 'downstaging'; b) naked eye inspection after application of 3-5% acetic acid (VIA); c) VIA using magnification devices (VIAM); d) visual inspection after the application of Lugol's iodine (VILI). Downstaging has been shown to be poorly sensitive and specific to detect cervical neoplasia and is no longer considered as a suitable screening test for cervical cancer. VIA, VIAM and VILI are currently being investigated in multicentre cross-sectional studies (without verification bias), in which cytology and HPV testing are also simultaneously evaluated, and the results of these investigations will be available in 2003. These studies will provide valuable information on the average, comparative test performances in detecting high-grade cervical cancer precursors and cancer. Results from pooled analysis of data from two completed studies indicated an approximate sensitivity of 93.4% and specificity of 85.1% for VIA to detect CIN 2 or worse lesions; the corresponding figures for cytology were 72.1% and 91.6%. The efficacy of VIA in reducing incidence of an mortality from cervical cancer and its cost-effectiveness is currently being investigated in two cluster randomized controlled intervention trials in India. One of these studies is a 4-arm trial addressing the comparative efficacy of VIA, cytology and primary screening with HPV DNA testing. This trial will provide valuable information on comparative detection rates of CIN 2-3 lesions by the middle of 2003. The expected outcomes from the Indian studies will contribute valuable information for guiding the development of public health policies on cervical cancer prevention in countries with different levels of socio-economic and health services development and open up new avenues of research. This paper is available too at: http//www.insp.mx/salud/index.html.

Royal Society of Tropical Medicine and Hygiene meeting at Manson House, London 17 January 2002. Cervical cancer in developing countries

The public health importance of cervical cancer is now increasingly appreciated as a means to improve the general health of women in many developing countries. Developing countries account for 80% of the world burden, mostly due to the lack of effective control programmes. Infection with oncogenic types of human papillomaviruses (HPV) has been established as the central cause for cervical cancer. Thus, vaccination against HPV is a potentially useful strategy for prevention, but this may take several years to become a reality. Currently, early detection and treatment is the most effective approach to control cervical cancer. Cervical cancer may be controlled through improving awareness and accessibility to diagnostic and treatment services. Cytology-based screening is beyond the capacity of health services in many developing countries, hence, alternative methods to cytology are being investigated. Visual inspection of the cervix after application of 3-5% acetic acid (VIA) seems to be a promising screening test, with a similar sensitivity to that of cytology, but lower specificity. Currently, it is being evaluated for its cost-effectiveness in reducing cervical cancer incidence and mortality in randomized trials. Information from the ongoing studies will be valuable for evolving cervical cancer control policies and programmes in low-resource settings.

Effect of stabilizing additives on the structure and hydration of proteins: a study involving monoclinic lysozyme

In pursuance of a long-range programme on the hydration, mobility and action of proteins, the structural basis of the stabilizing effect of sugars and polyols is being investigated. With two crystallographically independent molecules with slightly different packing environments in the crystal, monoclinic lysozyme constitutes an ideal system for exploring the problem. The differences in the structure and hydration of the two molecules provide a framework for examining the changes caused by stabilizing additives. Monoclinic crystals were grown under native conditions and also in the presence of 10% sucrose, 15% trehalose, 10% trehalose, 10% sorbitol and 5% glycerol. The crystal structures were refined at resolutions ranging from 1.8 to 2.1 A. The average B values, and hence the mobility of the structure, are lower in the presence of additives than in the native crystals. However, a comparison of the structures indicates that the effect of the additives on the structure and the hydration shell around the protein molecule is considerably less than that caused by differences in packing. It is also less than that caused by the replacement of NaNO(3) by NaCl as the precipitant in the crystallization experiments. This result is not in conformity with the commonly held belief that additives exert their stabilizing effect through the reorganization of the hydration shell, at least as far as the ordered water molecules are concerned.