Responding to eruptive transitions during the 2020-2021 eruption of La Soufrière volcano, St. Vincent

A critical challenge during volcanic emergencies is responding to rapid changes in eruptive behaviour. Actionable advice, essential in times of rising uncertainty, demands the rapid synthesis and communication of multiple datasets with prognoses. The 2020-2021 eruption of La Soufrière volcano exemplifies these challenges: a series of explosions from 9-22 April 2021 was preceded by three months of effusive activity, which commenced with a remarkably low level of detected unrest. Here we show how the development of an evolving conceptual model, and the expression of uncertainties via both elicitation and scenarios associated with this model, were key to anticipating this transition. This not only required input from multiple monitoring datasets but contextualisation via state-of-the-art hazard assessments, and evidence-based knowledge of critical decision-making timescales and community needs. In addition, we share strategies employed as a consequence of constraints on recognising and responding to eruptive transitions in a resource-constrained setting, which may guide similarly challenged volcano observatories worldwide.

Disaster aid? Mapping historical responses to volcanic eruptions from 1800-2000 in the English-speaking Eastern Caribbean: their role in creating vulnerabilities

This paper uses volcanic eruptions on the Caribbean islands of Montserrat and Saint Vincent to explore the role that British colonial rule in the past and near past (1800-2000) has played in response to and recovery from hazardous events, and in turn, the influence that the nature of the hazards has on these responses. It shows that systemic vulnerabilities to natural hazards have been created by inadequate aid responses and longer-term chronic problems and demonstrates that hazard impacts are compounded by them. Vulnerabilities could be reduced by analysing integrated hazard impacts to generate mitigative measures across hazards and identify actions that more closely match timescales of political decision-making. Incorporating local knowledge and experience into risk analysis will enable the most effective use of aid resources, ahead of emergencies. Finally, coupling aid for long-term development with emergency response would improve outcomes and adaptation to longer-term vulnerabilities in immediate rebuilding and short-term recovery.

A novel approach for evaluating contact patterns and risk mitigation strategies for COVID-19 in English primary schools with application of structured expert judgement

Personal contacts drive COVID-19 infections. After being closed (23 March 2020) UK primary schools partially re-opened on 1 June 2020 with social distancing and new risk mitigation strategies. We conducted a structured expert elicitation of teachers to quantify primary school contact patterns and how contact rates changed upon re-opening with risk mitigation measures in place. These rates, with uncertainties, were determined using a performance-based algorithm. We report mean number of contacts per day for four cohorts within schools, with associated 90% confidence ranges. Prior to lockdown, younger children (Reception and Year 1) made 15 contacts per day [range 8.35] within school, older children (Year 6) 18 contacts [range 5.55], teaching staff 25 contacts [range 4.55] and non-classroom staff 11 contacts [range 2.27]. After re-opening, the mean number of contacts was reduced by 53% for young children, 62% for older children, 60% for classroom staff and 64% for other staff. Contacts between teaching and non-teaching staff reduced by 80%. The distributions of contacts per person are asymmetric with heavy tail reflecting a few individuals with high contact numbers. Questions on risk mitigation and supplementary structured interviews elucidated how new measures reduced daily contacts in-school and contribute to infection risk reduction.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Meteorological Controls on Local and Regional Volcanic Ash Dispersal

Volcanic ash has the capacity to impact human health, livestock, crops and infrastructure, including international air traffic. For recent major eruptions, information on the volcanic ash plume has been combined with relatively coarse-resolution meteorological model output to provide simulations of regional ash dispersal, with reasonable success on the scale of hundreds of kilometres. However, to predict and mitigate these impacts locally, significant improvements in modelling capability are required. Here, we present results from a dynamic meteorological-ash-dispersion model configured with sufficient resolution to represent local topographic and convectively-forced flows. We focus on an archetypal volcanic setting, Soufrière, St Vincent, and use the exceptional historical records of the 1902 and 1979 eruptions to challenge our simulations. We find that the evolution and characteristics of ash deposition on St Vincent and nearby islands can be accurately simulated when the wind shear associated with the trade wind inversion and topographically-forced flows are represented. The wind shear plays a primary role and topographic flows a secondary role on ash distribution on local to regional scales. We propose a new explanation for the downwind ash deposition maxima, commonly observed in volcanic eruptions, as resulting from the detailed forcing of mesoscale meteorology on the ash plume.

Radical prostatectomy for locally advanced and metastatic prostate cancer

The management of advanced prostate cancer remains challenging. Traditionally, radical prostatectomy was discouraged in patients with locally advanced or node positive disease owing to the increased complication rate and treatment related morbidity. However, technical advances and refinements in surgical techniques have enabled the outcomes for patients with high risk prostate cancer to be improved. More recently, the concept of cytoreductive prostatectomy has been described where surgery (often Combined with an extended lymph node dissection) is performed in the setting of metastatic disease. Indirect evidence suggests an advantage using the cytoreductive approach. Hypothetical explanations for this observed benefit include decreased tumour burden, immune modulation, improved response to secondary treatment and avoidance of secondary complications attributable to local tumour growth. Nevertheless, prospective trials are required to investigate this further.

Transitions between explosive and effusive phases during the cataclysmic 2010 eruption of Merapi volcano, Java, Indonesia

Transitions between explosive and effusive activity are commonly observed during dome-forming eruptions and may be linked to factors such as magma influx, ascent rate and degassing. However, the interplay between these factors is complex and the resulting eruptive behaviour often unpredictable. This paper focuses on the driving forces behind the explosive and effusive activity during the well-documented 2010 eruption of Merapi, the volcano's largest eruption since 1872. Time-controlled samples were collected from the 2010 deposits, linked to eruption stage and style of activity. These include scoria and pumice from the initial explosions, dense and scoriaceous dome samples formed via effusive activity, as well as scoria and pumice samples deposited during subplinian column collapse. Quantitative textural analysis of groundmass feldspar microlites, including measurements of areal number density, mean microlite size, crystal aspect ratio, groundmass crystallinity and crystal size distribution analysis, reveal that shallow pre- and syn-eruptive magmatic processes acted to govern the changing behaviour during the eruption. High-An (up to ∼80 mol% An) microlites from early erupted samples reveal that the eruption was likely preceded by an influx of hotter or more mafic magma. Transitions between explosive and effusive activity in 2010 were driven primarily by the dynamics of magma ascent in the conduit, with degassing and crystallisation acting via feedback mechanisms, resulting in cycles of effusive and explosive activity. Explosivity during the 2010 eruption was enhanced by the presence of a 'plug' of cooled magma within the shallow magma plumbing system, which acted to hinder degassing, leading to overpressure prior to initial explosive activity.

Chapter 16 Pre-eruptive vapour and its role in controlling eruption style and longevity at Soufrière Hills Volcano

We use volatiles in melt inclusions and nominally anhydrous phenocrysts, with volcanic gas flux and composition, and textural analysis of mafic inclusions to estimate the mass of exsolved vapour prior to eruption at Soufrière Hills Volcano (SHV). Pre-eruptive andesite coexists with exsolved vapour comprising 1.6–2.4 wt% of the bulk magma. The water content of orthopyroxenes indicates a zone of magma storage at pressures of approximately 200–300 MPa, whereas melt inclusions have equilibrated at shallower pressures. Inclusions containing >3 wt% H2O are enriched in CO2, suggesting flushing with CO2-rich gases. Intruding mafic magma contains >8 wt% H2O at 200–300 MPa. Rapid quenching is accompanied by crystallization and vesiculation. Upon entrainment into the andesite, mafic inclusions may undergo disaggregation, where expansion of volatiles in the interior overcomes the strength of the crystal frameworks, thereby recharging the vapour content of the andesite. Exsolved vapour may amount to 4.3–8.2 vol% at 300 MPa, with implications for eruption longevity and volume; we estimate the magma reservoir volume to be 60–200 km3. Exsolved vapour may account for the small volume change at depth during eruptions from geodetic models, and has implications for magma flow: exsolution is likely to be in equilibrium during rapid magma ascent, with little nucleation of new bubbles.

Chapter 18 Characterization of mafic enclaves in the erupted products of Soufrière Hills Volcano, Montserrat, 2009 to 2010

Lavas from the current eruption of the Soufrière Hills Volcano (SHV), Montserrat exhibit evidence for magma mingling, related to the intrusion of mafic magma at depth. We present detailed field, petrological, textural and geochemical descriptions of mafic enclaves in andesite erupted during 2009–2010, and subdivide the enclaves into three distinct types: type A are mafic, glassy with chilled margins and few inherited phenocrysts; type B are more evolved with high inherited phenocryst content and little glass, and are interpreted as significantly hybridized; type C are composite, with a mafic interior (type A) and a hybrid exterior (type B). All enclaves define tight linear compositional trends, interpreted as mixing between a mafic end member (type A) and host andesite. Enclave glasses are rhyolitic, owing to extensive crystallization during quenching. Type A quench crystallization is driven by rapid thermal equilibration during injection into the andesite. Conversely, type B enclaves form in a hybridized melt layer, which ponded near the base of the chamber and cooled more slowly. Vesiculation near the mafic–silicic interface resulted in disruption of the hybridized layer and the formation of the type B enclaves. The composite enclaves represent an interface between types A and B, suggesting multiple episodes of mafic injection.

Framing volcanic risk communication within disaster risk reduction: finding ways for the social and physical sciences to work together

Sixteen years have passed since the last global volcanic event and more than 25 since a volcanic catastrophe that killed tens of thousands. In this time, volcanology has seen major advances in understanding, modelling and predicting volcanic hazards and, recently, an interest in techniques for reducing and mitigating volcanic risk. This paper provides a synthesis of literature relating to this last aspect, specifically the communication of volcanic risk, with a view to highlighting areas of future research into encouraging risk-reducing behaviour. Evidence suggests that the current ‘multidisciplinary’ approach within physical science needs a broader scope to include sociological knowledge and techniques. Key areas where this approach might be applied are: (1) the understanding of the incentives that make governments and communities act to reduce volcanic risk; (2) improving the communication of volcanic uncertainties in volcanic emergency management and long-term planning and development. To be successful, volcanic risk reduction programmes will need to be placed within the context of other other risk-related phenomena (e.g. other natural hazards, climate change) and aim to develop an all-risks reduction culture. We suggest that the greatest potential for achieving these two aims comes from deliberative inclusive processes and geographic information systems.

B-type natriuretic peptide and the prediction of outcome in patients admitted to intensive care

B-type natriuretic peptide is known to predict outcome in congestive cardiac failure and myocardial infarction. We aimed to determine whether measurement of B-type natriuretic peptide would predict hospital mortality in patients admitted to an intensive care unit. We conducted a prospective observational cohort study in 78 consecutive patients. Demographics, clinical details and clinical outcomes were recorded. Admission and 24 h B-type natriuretic peptide and cardiac troponin I levels were measured. B-type natriuretic peptide and cardiac troponin I levels taken on intensive care admission and 24 h after admission did not accurately predict hospital mortality for all patients, including patients with severe sepsis or septic shock (all p > 0.05). B-type natriuretic peptide levels were higher in patients with severe sepsis and septic shock (p = 0.02), in patients > or = 65 years (p = 0.04) and in patients with raised creatinine > or = 110 micromol.l(-1) (p = 0.02). We concluded that B-type natriuretic peptide, measured soon after admission to intensive care, does not usefully predict outcome after intensive care.

Generation of a debris avalanche and violent pyroclastic density current on 26 December (Boxing Day) 1997 at Soufrière Hills Volcano, Montserrat

Growth of an andesitic lava dome at Soufriere Hills Volcano, Montserrat, beginning in November 1995, caused instability of a hydrothermally altered flank of the volcano. Catastrophic failure occurred on 26 December 1997, 14 months after the instability was first recognized. Two months before failure a dome lobe had extruded over the unstable area and by 25 December 1997 this had a volume of 113 x 106m3. At 03:01 (local time) the flank rocks and some dome talus failed and generated a debris avalanche (volume 46 x 106 m3). Between 35 and 45 x 106 m3 of the dome then collapsed, generating a violent pyroclastic density current that devastated 10 km2 of southern Montserrat. The failure of the flank and dome formed two adjacent bowl-shaped collapse depressions. The most intense activity lasted about 11.6 minutes. The hummocky debris avalanche deposit is composed of a mixture of domains of heterolithic breccia. The pyroclastic density current had an estimated peak velocity of 80-90 ms-1, and minimum flux of 108 kgs1. The current was largely erosional on land with most deposition out at sea. Destructive effects included removal of houses, trees and large vehicles, and formation of a scoured surface blackened by a thin (3-4 mm) layer of tar. Two discrete depositional units formed from the pyroclastic density current, each with a lower coarse-grained layer and an upper fine-grained stratified layer. These deposits are overlain by an ashfall layer related to buoyant lofting of the current. Flank failure is attributed to loading of hydrothermally weakened rocks by the dome. The generation of the pyroclastic density current is attributed to failure and explosive disintegration of the dome, involving release and violent expansion of gases initially at high pore pressures.

Inhibition of telomerase by site-specific ribonucleases in gastric and esophageal adenocarcinoma

Increased expression of telomerase is critical in the pathogenesis of cancer. Telomerase expression is reported variably in foregut cancers, possibly as a result of telomerase inhibition or ribonucleases. We performed experiments to assess telomerase and telomerase RNA expression in foregut cancers and to quantify and characterize telomerase inhibition. Cancer specimens were obtained from 27 patients. Telomerase activity of cancers was determined by the telomeric repeat amplification protocol, the presence of telomerase RNA component (hTERC) by reverse transcription PCR, and the quantity of telomerase inhibitors in mixing experiments. Ribonuclease activity was measured by assessing degradation of labeled RNA by cancers. Telomerase was found in 8/11 adenocarcinomas of the esophagus or gastroesophageal junction and 6/16 distal gastric adenocarcinomas; hTERC was detectable in all cancers. Telomerase inhibition was more marked in distal compared to proximal adenocarcinomas (P = 0.01) and correlated with ribonuclease activity (rS = 0.65). Ribonucleases contribute significantly to telomerase inhibitory activity detectable in foregut cancer specimens. In vitro, the presence of telomerase inhibitors in some specimens did not prevent the detection of telomerase by the TRAP assay. This suggests a more complex relationship between telomerase and its inhibitors. Site-specificity of telomerase inhibitors generally and ribonuclease activity specifically suggests a putative regulatory role in vivo.

Ducky mouse phenotype of epilepsy and ataxia is associated with mutations in the Cacna2d2 gene and decreased calcium channel current in cerebellar Purkinje cells

The mouse mutant ducky, a model for absence epilepsy, is characterized by spike-wave seizures and ataxia. The ducky gene was mapped previously to distal mouse chromosome 9. High-resolution genetic and physical mapping has resulted in the identification of the Cacna2d2 gene encoding the alpha2delta2 voltage-dependent calcium channel subunit. Mutations in Cacna2d2 were found to underlie the ducky phenotype in the original ducky (du) strain and in a newly identified strain (du(2J)). Both mutations are predicted to result in loss of the full-length alpha2delta2 protein. Functional analysis shows that the alpha2delta2 subunit increases the maximum conductance of the alpha1A/beta4 channel combination when coexpressed in vitro in Xenopus oocytes. The Ca(2+) channel current in acutely dissociated du/du cerebellar Purkinje cells was reduced, with no change in single-channel conductance. In contrast, no effect on Ca(2+) channel current was seen in cerebellar granule cells, results consistent with the high level of expression of the Cacna2d2 gene in Purkinje, but not granule, neurons. Our observations document the first mammalian alpha2delta mutation and complete the association of each of the major classes of voltage-dependent Ca(2+) channel subunits with a phenotype of ataxia and epilepsy in the mouse.

Development, standardization, and testing of a lexicon for reporting contrast-enhanced breast magnetic resonance imaging studies

The purpose of this study was to develop, standardize, and test reproducibility of a lexicon for reporting contrast-enhanced breast magnetic resonance imaging (MRI) examinations. To standardize breast MRI lesion description and reporting, seven radiologists with extensive breast MRI experience developed consensus on technical detail, clinical history, and terminology reporting to describe kinetic and architectural features of lesions detected on contrast-enhanced breast MR images. This lexicon adapted American College of Radiology Breast Imaging and Data Reporting System terminology for breast MRI reporting, including recommendations for reporting clinical history, technical parameters for breast MRI, descriptions for general breast composition, morphologic and kinetic characteristics of mass lesions or regions of abnormal enhancement, and overall impression and management recommendations. To test morphology reproducibility, seven radiologists assessed morphology characteristics of 85 contrast-enhanced breast MRI studies. Data from each independent reader were used to compute weighted and unweighted kappa (kappa) statistics for interobserver agreement among readers. The MR lexicon differentiates two lesion types, mass and non-mass-like enhancement based on morphology and geographical distribution, with descriptors of shape, margin, and internal enhancement. Lexicon testing showed substantial agreement for breast density (kappa = 0.63) and moderate agreement for lesion type (kappa = 0.57), mass margins (kappa = 0.55), and mass shape (kappa = 0.42). Agreement was fair for internal enhancement characteristics. Unweighted kappa statistics showed highest agreement for the terms dense in the breast composition category, mass in lesion type, spiculated and smooth in mass margins, irregular in mass shape, and both dark septations and rim enhancement for internal enhancement characteristics within a mass. The newly developed breast MR lexicon demonstrated moderate interobserver agreement. While breast density and lesion type appear reproducible, other terms require further refinement and testing to lead to a uniform standard language and reporting system for breast MRI. J. Magn. Reson. Imaging 2001;13:889-895.

Impact of emerging technologies and regulations on the role of POCT

Point-of-care testing (POCT) can be introduced by laboratory directors or clinicians in response to the need for rapid results to guide treatment. The professional responsibility for ensuring reliable and accurate results is well-defined in some countries such as France, but the role and responsibility of the laboratory is less clear in many other places. When point-of-care instrument technology and the intrinsic design of the device leads to device-specific parameters or analytical differences from laboratory-based equipment, there is a risk of misinterpretation and erroneous treatment decisions. Laboratory staffs are more often aware of the interaction of analytical technology and result interpretation than clinicians, making it more rational to involve the laboratory in the selection of point-of-care equipment, procedures, and therapeutic decisions based on the results. The design control and risk-analysis provisions of emerging regulations such as the EU in vitro diagnostic medical device (IVD) can be interpreted as engaging the manufacturer's responsibility, even when the equipment is functioning according to specification. This is especially true of device-specific parameters in which cross-calibration or traceability to a reference material or method is not possible. This is a further argument for involvement of the laboratory in the selection and implementation of point-of-care testing devices.

An approach to analysis of large-scale correlations between genome changes and clinical endpoints in ovarian cancer

This report describes analyses of associations of genome copy number abnormalities in ovarian cancers with clinical features using genome-wide graphical and analytical procedures. These studies show that tumor grade is a better indicator of the extent of genomic progression than stage, that loss of chromosome 4 occurs preferentially in high-grade tumors, and that gains of 3q26-qter, 8q24-qter, and 20q13-qter occur frequently in low-grade and low-stage tumors and thus may be early events in ovarian cancer development. In addition, loss of chromosome 16q24 and a total number of independent genome copy number aberrations >7 are associated with reduced survival duration. The association of loss of 16q24 (D16S3026) with decreased survival duration was confirmed by quantitative PCR. Regions that frequently are abnormal and associated with altered survival duration are strong candidates for higher resolution analysis and gene discovery and may be useful markers for prediction of clinical outcome.

Dynamic high-spatial-resolution MR imaging of suspicious breast lesions: diagnostic criteria and interobserver variability

OBJECTIVE

Our study was undertaken to develop diagnostic rules and to assess the reproducibility of dynamic and morphologic parameters for the characterization of suspicious breast lesions using dynamic high-spatial-resolution MR imaging.

MATERIALS AND METHODS

Fifty-seven patients with suspicious mammographic or palpable findings underwent preoperative contrast-enhanced MR imaging of the breast using a three-time-point method of acquisition. Each lesion was prospectively analyzed by two independent radiologists for morphologic and visual dynamic enhancement characteristics. A classification and regression tree was used to examine the optimal order, cutoff points, and combination of imaging parameters to build a diagnostic rule separating benign from malignant lesions using histopathology findings as the standard of reference. Kappa statistics were used to determine observer variability.

RESULTS

Among 23 benign and 34 malignant lesions (12 invasive, three ductal carcinoma in situ, and 19 mixed cancer), margin morphology (p = 0.001) and enhancement pattern (p = 0.001) were the most significant MR imaging findings for lesion characterization. Focal mass lesions were classified as malignant when spiculated margins or both the washout enhancement pattern and "nonsmooth" margins were present. Interobserver agreement was almost perfect for washout pattern and substantial for margin assessment. In the limited population tested retrospectively, the diagnostic rule yielded a sensitivity and positive predictive value of 97% each and a specificity and negative predictive value of 96% each.

CONCLUSION

The washout enhancement pattern combined with lesion margin assessment on dynamic contrast-enhanced high-resolution MR imaging of the breast allows reproducible lesion characterization and may be a highly specific diagnostic tool.

Mortality among women with ductal carcinoma in situ of the breast in the population-based surveillance, epidemiology and end results program

BACKGROUND

Over 14% of breast cancers diagnosed in the United States annually are ductal carcinomas in situ (DCIS). There are no published population-based reports of the likelihood of breast cancer death among US women with DCIS.

METHODS

We used data from the Surveillance, Epidemiology and End Results program to determine the likelihood of breast cancer death at 5 and 10 years among US women aged 40 and older diagnosed with DCIS from 1978 to 1983 (before screening mammography was common; n = 1525) and from 1984 to 1989 (when screening mammography became common; n = 5547). We also calculated standardized mortality ratios (SMRs) to compare observed deaths from breast cancer, cardiovascular disease, and all causes combined among women with DCIS with deaths expected based on general population mortality rates.

RESULTS

Among women diagnosed with DCIS from 1978 to 1983, 1.5% died of breast cancer within 5 years and 3.4% within 10 years. Among women diagnosed from 1984 to 1989, 0.7% died of breast cancer within 5 years and 1.9% within 10 years. Relative to the general population, risk of breast cancer death was greater for women diagnosed from 1978 to 1983 (SMR, 3.4; 95% confidence interval [CI], 2.5-4.5) than for women diagnosed from 1984 to 1989 (10-year SMR, 1.9; 95% CI, 1.5-2.3). Women diagnosed from 1984 to 1989 were significantly less likely than women in the general population to have died of cardiovascular diseases (10-year SMR, 0.6; 95% CI, 0.5-0.7) or of all causes combined (SMR, 0.8; 95% CI, 0.7-0.8).

CONCLUSIONS

Among women diagnosed with DCIS, risk of death from breast cancer was low, at least within the 10 years following diagnosis. This may reflect the effectiveness of treatment for DCIS, the "benign" nature of DCIS, or both. At 10 years, women diagnosed from 1984 to 1989 were less likely than women diagnosed from 1978 to 1983 to have died of breast cancer, and their risk of dying of all causes combined was lower than that in the general population.

Studies of the lethargic (lh/lh) mouse model of absence seizures: regulatory mechanisms and identification of the lh gene

To understand the cellular and molecular mechanisms that underlie generalized absence seizures sufficiently well to design rational, efficacious new therapies for patients, it is necessary to turn to animal models to gain insights into these mechanisms. The lethargic (lh/lh) mutant mouse expresses spontaneous absence seizures that share behavioral, electrographic, and anticonvulsant profiles with absence seizures in patients. This validates its use to study the mechanisms that underlie absence seizures. This chapter discusses two scientific approaches that involve the use of lh/lh mice. The first part of the chapter discusses neurobiologic approaches used to investigate critical mechanisms that regulate the synchronized burst firing within the thalamocortical network that generates absence seizures. Two of these critical mechanisms have been studied in detail with lh/lh mice. The first critical mechanism involves the required activation of gamma-aminobutyric acid B (GABAB) receptors to generate absence seizures. Because the numbers of GABAB receptors are increased in thalamocortical populations among lh/lh mice compared with littermates without epilepsy, these receptors appear to play a pathophysiologic role in the expression of absence seizures among lh/lh mice. Moreover, there may be a role for GABAB receptors in the generation of absence seizures among humans, because administration of compounds that activate GABAB receptors can produce absence seizures among humans. These findings suggest that GABAB receptor antagonists may represent a new class of antiabsence compounds that will be efficacious against absence seizures among patients. A second critical mechanism that regulates generation of absence seizures involves GABAA receptors in the nucleus reticularis thalami (NRT), a nucleus that sends GABA-ergic afferents to thalamic relay nuclei. Activation of GABAA receptors in the NRT appears to suppress the generation of absence seizures among lh/lh mice and in other models. Moreover, clonazepam may exert its antiabsence actions through this mechanism. Together, these findings suggest that compounds that selectively activate GABAA receptor isoforms expressed in NRT may represent a class of antiabsence drugs that could have fewer side effects than compounds currently used to treat patients. The second part of the chapter discusses a molecular genetic approach to delineation of the mechanisms that underlie absence seizures. Absence seizures among lh/lh mice are caused by a single-gene defect on chromosome 2. If positional cloning and gene isolation techniques are successful, it will be possible to identify the lh disease gene. Subsequent studies of the lh gene product should greatly increase not only our understanding of the pathophysiologic basis for absence seizures among lh/lh mice but also our ability to seek similar mutations in homologous genes in human families that express absence seizures. Accordingly, strategies and progress in cloning and identifying the lh disease gene are presented.

Mouse models of spike-wave epilepsy

The mouse is a well-established model for human genetic disorders. An increasing number of single-gene human diseases are being elucidated through the use of mouse models. Recently genes for three of the six well-characterised single locus models for human spike-wave epilepsy have been isolated and published. The tottering mouse has been shown to be due to mutations in the gene encoding the high voltage-activated alpha1A calcium channel subunit. The lethargic mouse has been shown to be due to mutations in the gene encoding another calcium channel subunit, beta4. The slow-wave epilepsy mouse phenotype is the result of loss of function of the ubiquitous sodium hydrogen exchanger NHEI. These genes and the pathways they are involved in are now candidates for human spike-wave epilepsy. The six mouse models and those genes underlying the spike-wave phenotype are discussed in conjunction with how these mutations were discovered and how they may give rise to the seizure phenotypes. Several nonepilepsy human neurologic disorders have been shown to be allelic with the tottering mouse. The question this raises as to the validity of these models for human spike-wave epilepsy is considered. Finally, the effect these discoveries will have on the understanding and treatment of human spike-wave epilepsy are discussed.

Predictors of visits to commercial sex workers by male attendees at sexually transmitted disease clinics in southern Vietnam

OBJECTIVES

To determine the HIV/sexually transmitted disease (STD) status of male patients at STD clinics and factors associated with frequent visits to commercial sex workers (CSW) in southern Vietnam.

DESIGN

Cross-sectional survey.

METHODS

Confidential interviews and physical and laboratory evaluation of 804 male patients at STD clinics in two semi-rural provinces in the Mekong delta.

RESULTS

HIV seroprevalence was 0.5%. The prevalence of urethritis syndrome was 19.3%, gonorrhea 10.2% (Gram-stain positive) and syphilis 2% (reactive rapid plasma reagin test). All the men had visited CSW in the past and 58% had their first sexual experience with a CSW; 73% had visited a CSW in the last 3 years. Married men were equally as likely as single men to have casual partners or to have visited a CSW. The men recruited CSW more from the streets (45%) than from brothels (38%). Factors independently associated with visiting a CSW in the last 3 years included being single [odds ratio (OR), 2.2], age under 20 years (OR, 1.9), having first sexual intercourse with a CSW (OR, 2.1), not having a current girlfriend (OR, 2.1), using alcohol before sex (OR, 2.7) and drug use (OR, 1.8). Only 7% of men used condoms consistently; 70% had never used them. Only 37% had used a condom last time they had intercourse with a CSW.

CONCLUSIONS

Prevention programs for men in Vietnam, particularly those who are young or single, need to focus on reducing drug and alcohol consumption and improving condom use with CSWs.

Utility of magnetic resonance imaging in the management of breast cancer: evidence for improved preoperative staging

PURPOSE

The staging and treatment for breast cancer are changing; there is an increase in the incidence of ductal carcinoma-in-situ, the use of fine-needle aspiration and stereotactic biopsy for diagnosis, and the use of neoadjuvant chemotherapy. Thus, there is a need for a tool to assess more precisely the extent of cancer in the breast before surgery. To better plan surgical and chemotherapeutic interventions, we evaluated high-resolution magnetic resonance imaging (MRI) as such a tool.

PATIENTS AND METHODS

Fifty-seven patients with 58 cases of breast cancer were evaluated preoperatively with MRI using a technique called the triple-acquisition rapid gradient echo technique to maximize anatomic detail. Imaging results were compared with mammography and subsequent pathology results.

RESULTS

Magnetic resonance imaging correctly identified residual or primary cancer in 55 of 58 cases and accurately predicted the extent of the cancer in 54 of 58 cases. The anatomic extent was more accurately defined with MRI compared with mammography (98% v 55%). Magnetic resonance imaging added the greatest value in cases of multifocal disease.

CONCLUSION

By applying MRI selectively to patients with a known diagnosis of cancer and focusing on defining the extent of malignant lesions, we were able to obtain clear and accurate anatomic information. Our results suggest that MRI could provide very valuable information for preoperative planning and single-stage resection in breast cancer. Based on preliminary data from our series, MRI would be valuable as a staging tool in the preoperative setting even if the cost is in the range of $1,300 to $2,000. It is already significantly less than the target cost, so it is reasonable to refine this technique for clinical use to help plan the most appropriate surgical intervention and possibly reduce costs as well. A careful prospective study is warranted to validate our findings.

Variability and accuracy in mammographic interpretation using the American College of Radiology Breast Imaging Reporting and Data System

BACKGROUND

Several studies, which were limited by their small sample size and selection of difficult cases for review, have reported substantial variability among radiologists in interpretation of mammographic examinations. We have determined, in the largest study to date, intraobserver and interobserver agreement in interpreting screening mammography and accuracy of mammography by use of the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS).

METHODS

The mammographic examinations were randomly selected on the basis of original mammographic interpretation and cancer outcome from 71,713 screening examinations performed by the Mobile Mammography Screening Program of the University of California, San Francisco, during the period from April 1985 through February 1995. The final sample included 786 abnormal examinations with no cancer detected, 267 abnormal examinations with cancer detected, and 1563 normal examinations. Films were read separately by two radiologists according to BI-RADS. Cancer status was determined by contacting women's physicians and by linkage to the regional Surveillance, Epidemiology, and End Results Program.

RESULTS

There was moderate agreement between radiologists in reporting the presence of a finding when cancer was present (kappa = 0.54) and substantial agreement when cancer was not present (kappa = 0.62). Agreement was moderate in assigning one of the five assessment categories but was statistically significantly lower when cancer was present relative to when cancer was not present (kappa = 0.46 versus 0.56; two-sided P = .02). Agreement for reporting the presence of a finding and mammographic assessment was two-fold more likely for examinations with less dense breasts. Agreement was higher on repeat readings by the same radiologists than between radiologists. The sensitivity of mammography was lower with BI-RADS than with the original system for mammographic interpretation, but the positive predictive value of mammography was higher.

CONCLUSION

Considerable variability in interpretation of mammographic examinations exists; this variability and the accuracy of mammography are neither improved nor diminished with use of BI-RADS.

Outcomes of modern screening mammography

The University of California, San Francisco, Mobile Mammography Screening Program is a low-cost, community-based breast cancer screening program that offers mammography to women of diverse ethnic backgrounds (36% nonwhite) in six counties in northern California. Analysis of data collected on approximately 34,000 screening examinations from this program shows that the positive predictive value and sensitivity of modern screening mammography to be lower for women aged 40 to 49 years compared to women aged 50 and older. This lower performance is due to the lower prevalence of invasive breast cancer in younger women and possibly to age differences in breast tumor biology. Because of this lower performance, women in their forties may be subjected to more of the negative consequences of screening, which include additional diagnostic evaluations and the associated morbidity and anxiety, the potential for detecting and surgically treating clinically insignificant breast lesions, and the false reassurance resulting from normal mammographic results. Since the evidence is not compelling that the benefits of mammography screening outweigh the known risks for women aged 40 to 49 years, women considering mammography screening should be informed of the risks, potential benefits, and limitations of screening mammography, so that they can make individualized decisions based on their personal risk status and utility for the associated risks and potential benefits of screening.

Increases in ductal carcinoma in situ (DCIS) of the breast in relation to mammography: a dilemma

The increased use of screening mammography has resulted in a marked increase in detected cases of ductal carcinoma in situ (DCIS) of the breast since the early 1980s. In 1993, there were an estimated 23,275 newly diagnosed cases of DCIS in the United States, of which 4,676 were in women aged 40-49. DCIS accounted for 14.7% of all newly diagnosed breast cancers in women aged 40-49 in 1993, and perhaps 40% of all mammographically detected breast cancers in this age group are DCIS. Among women aged 40-49, an estimated 1,890 mastectomies and 2,707 lumpectomies (with or without radiation) were performed for DCIS in 1993. There is an urgent need to better understand the relationship of mammographically detected DCIS to invasive and potentially life-threatening breast cancer. Better information about the appropriate treatment of DCIS is also needed to reduce the confusion and uncertainty many women and their physicians currently experience in the face of a DCIS diagnosis. For the present, women considering screening mammography should be told the likelihood of being diagnosed with DCIS and that only some DCIS cases may be clinically significant but almost all will be treated surgically.

Cloning and characterization of alpha1H from human heart, a member of the T-type Ca2+ channel gene family

Voltage-activated Ca2+ channels exist as multigene families that share common structural features. Different Ca2+ channels are distinguished by their electrophysiology and pharmacology and can be classified as either low or high voltage-activated channels. Six alpha1 subunit genes cloned previously code for high voltage-activated Ca2+ channels; therefore, we have used a database search strategy to identify new Ca2+ channel genes, possibly including low voltage-activated (T-type) channels. A novel expressed sequence-tagged cDNA clone of alpha1G was used to screen a cDNA library, and in the present study, we report the cloning of alpha1H (or CavT.2), a low voltage-activated Ca2+ channel from human heart. Northern blots of human mRNA detected more alpha1H expression in peripheral tissues, such as kidney and heart, than in brain. We mapped the gene, CACNA1H, to human chromosome 16p13.3 and mouse chromosome 17. Expression of alpha1H in HEK-293 cells resulted in Ca2+ channel currents displaying voltage dependence, kinetics, and unitary conductance characteristic of native T-type Ca2+ channels. The alpha1H channel is sensitive to mibefradil, a nondihydropyridine Ca2+ channel blocker, with an IC50 of 1.4 micromol/L, consistent with the reported potency of mibefradil for T-type Ca2+ channels. Together with alpha1G, a rat brain T-type Ca2+ channel also cloned in our laboratory, these genes define a unique family of Ca2+ channels.

Molecular characterization of a neuronal low-voltage-activated T-type calcium channel

The molecular diversity of voltage-activated calcium channels was established by studies showing that channels could be distinguished by their voltage-dependence, deactivation and single-channel conductance. Low-voltage-activated channels are called 'T' type because their currents are both transient (owing to fast inactivation) and tiny (owing to small conductance). T-type channels are thought to be involved in pacemaker activity, low-threshold calcium spikes, neuronal oscillations and resonance, and rebound burst firing. Here we report the identification of a neuronal T-type channel. Our cloning strategy began with an analysis of Genbank sequences defined as sharing homology with calcium channels. We sequenced an expressed sequence tag (EST), then used it to clone a full-length complementary DNA from rat brain. Northern blot analysis indicated that this gene is expressed predominantly in brain, in particular the amygdala, cerebellum and thalamus. We mapped the human gene to chromosome 17q22, and the mouse gene to chromosome 11. Functional expression of the channel was measured in Xenopus oocytes. Based on the channel's distinctive voltage dependence, slow deactivation kinetics, and 7.5-pS single-channel conductance, we conclude that this channel is a low-voltage-activated T-type calcium channel.

Men with sexually transmitted diseases in Bangkok: where do they go for treatment and why?

OBJECTIVES

To describe and identify predictors of health-care seeking behavior among men with sexually transmitted diseases (STDs) in Bangkok, Thailand.

DESIGN

Cross-sectional survey.

METHODS

Men presenting with STDs were recruited from government clinics (n = 101), private clinics (n = 50) and pharmacies (n = 62). They completed interviewer-administered questionnaires on risk behavior, patterns of treatment-seeking for current and past STDs and attitudes toward health care.

RESULTS

Two-thirds of all subjects had had a previous STD. Approximately one-half believed a partner other than a sex worker was the source of their current infection. Of the sample, 39% of men seen initially at drugstores, 29% at private clinics and 19% at government clinics sought subsequent treatment; failure to respond to therapy was the primary reason for seeking additional care. Men attending drugstores were likely to be younger, have less education and income, and to practice riskier sexual behavior. Patients at drugstores and general private clinics received the least amount of counseling or STD testing, while those attending specialized private STD clinics received the most comprehensive services. Attitudes towards government clinics were uniformly positive regardless of the site of enrollment; conversely, about 50% of clients at drugstores felt that the advice and treatment they received were inadequate. Convenience, affordability and lack of embarrassment were associated with choice of treatment site.

CONCLUSIONS

STD/HIV control in Thailand must focus on improved treatment and counseling at the point of first encounter in the health-care system, particularly in the private sector. Men may be dissuaded from attending government clinics because of lack of convenience. Syndromic case management, incorporation of STD care at other public clinics and the recognition that more men practice unsafe sex with partners other than sex workers could improve STD control.

Comparison of risk factors for ductal carcinoma in situ and invasive breast cancer

BACKGROUND

Ductal carcinoma in situ (DCIS) accounts for approximately 12% of newly diagnosed breast cancers. Knowledge of the factors that predict who will be diagnosed with DCIS is very limited.

PURPOSE

The goal of this study was to determine risk factors associated with DCIS and whether these risk factors are similar to those associated with invasive breast cancer.

METHODS

We conducted a cross-sectional study of 39,542 women aged 30 years and older who underwent a screening mammographic examination at the University of California San Francisco Mobile Mammography Screening Program from April 1985 through September 1995. A breast cancer risk profile and clinical history were obtained for each woman. Follow-up after abnormal mammography was performed to determine the presence of DCIS or invasive breast cancer by contacting the women's physicians and by linkage to the regional Surveillance, Epidemiology, and End Results cancer registry. Multivariate analysis was performed by the use of polytomous logistic regression. Two-sided statistical tests were used to determine P values.

RESULTS

Among women aged 30-49 years, a family history of breast cancer (i.e., at least one affected first degree relative) was associated with an increased risk of DCIS (Odds ratio [OR] = 2.4; 95% confidence interval [CI] = 1.1-4.9) and body mass index greater than or equal to 25 kg/m2 was associated with a decreased risk of DCIS (OR = 0.4, 95% CI = 0.2 to 0.9). For each of these factors, there was a trend in the same direction bordering on statistical significance for invasive cancer (ORs = 1.7 [95% CI = 0.9-3.4] and 0.6 [95% CI = 0.3-1.1], respectively). Report of a palpable mass was associated with an increased risk of invasive cancer among women aged 30-49 years (OR = 12.0; 95% CI = 7.1-20.0); there was a trend in the same direction for DCIS (OR = 2.0; 95% CI = 0.8-5.1), but the association was much stronger for invasive disease than for DCIS (OR = 6.0; 95% CI = 2.1-18.0; P = .001). Among women aged 50 years and older, family history of breast cancer and nulliparity or age at birth of first child of 30 years or older increased the risk of both DCIS (ORs = 2.2 [95% CI = 1.0-4.2] and 2.3 [95% CI = 1.3-3.8], respectively) and invasive breast cancer (ORs = 1.5 [95% CI = 1.0-2.2] and 1.6 [95% CI = 1.2-2.1], respectively). Report of a palpable mass was not associated with an increased risk of DCIS among women 50 years and older, but it was strongly associated with an increased risk of invasive cancer (OR = 9.3; 95% CI = 6.0-14.0). Increasing age was associated with an increased risk of both DCIS and invasive cancer among women aged 30-49 years, but the association was stronger for invasive disease; a trend in the same direction bordering on statistical significance was observed for women aged 50 years and older.

CONCLUSION

Risk factors for DCIS are similar to those for invasive breast cancer.

IMPLICATIONS

More research is needed to better understand the malignant potential of DCIS lesions and factors that predict which lesions will become invasive breast cancer if left untreated.

Physical analysis of the region deleted in the tw18 allele of the mouse tcl-4 complementation group

We have generated a YAC contig of at least 3.3 Mb from the proximal region of In(17)4 of mouse chromosome 17. This region corresponds to DNA lost in the gastrulation mutant tw18, which belongs to the tcl-4 complementation group. Our most proximal and distal probes lie within the deletion-3.3 Mb apart-indicating that we have not cloned the entire region. The deleted region is contained in a genetic interval of less than 1 cM, suggesting that some suppression of recombination must occur.

Likelihood ratios for modern screening mammography. Risk of breast cancer based on age and mammographic interpretation

OBJECTIVE

To determine the sensitivity, specificity, and likelihood ratios (LRs) for modern screening mammography by decade of age and mammographic interpretation.

DESIGN

Cross-sectional.

SETTING

Nine counties in northern California.

PARTICIPANTS

A total of 26,057 women aged 30 years and older who underwent a total of 41,747 first and subsequent screening mammographic examinations at the Mobile Mammography Screening Program of the University of California, San Francisco, from April 1985 to September 1991.

MEASUREMENTS

Breast cancer risk profile, 2 standard mammographic views per breast, and follow-up of abnormal and normal mammograms of contacting women's physicians and by linkage to the regional Surveillance, Epidemiology, and End Results tumor registry. False-negative examinations were normal examinations that occurred within 13 months of a diagnosis of invasive breast cancer or ductal carcinoma in situ.

RESULTS

The sensitivity of first screening mammography increased with age: 77.3% for ages 30 to 39 years, 86.7% for ages 40 to 49 years, 93.6% for ages 50 to 59 years, 94.1% for ages 60 to 69 years, and 91.2% for ages 70 years and older (P = .04). Specificity was similar for all ages, ranging from 92.6% to 95.2%. Of all abnormal first screening examinations, 92.9% were reported as "additional evaluation needed." The LRs for that category ranged from 5.2 to 8.8 and did not vary with age. Based on the risk of breast cancer before mammography, which increases with age, the risk of breast cancer after mammography associated with these LRs were 0.01 for ages 30 to 39 years, 0.02 for ages 40 to 49 years, 0.05 for ages 50 to 59 years, 0.07 for ages 60 to 69 years, and 0.07 for ages 70 years and older. The LRs for mammography reported as "suspicious for malignancy" ranged from 88 to 144 and did not vary across age groups. These LRs were associated with a risk of breast cancer about 10 times greater than when mammography was reported as "additional evaluation needed."

CONCLUSION

Most abnormal first screening mammography are interpreted as "additional evaluation needed" and are associated with LRs of about 7. Given this low LR, the risk of breast cancer after mammography is primarily influenced by a woman's age-specific risk of breast cancer before mammography. The LRs for screening mammography interpreted as "suspicious for malignancy" are high (about 124) and are associated with a substantial increase in the risk of breast cancer irrespective of age, but these interpretations comprise only a small proportion of abnormal mammography.

Incidence of and treatment for ductal carcinoma in situ of the breast

OBJECTIVE

To describe trends in incidence and treatment for ductal carcinoma in situ (DCIS) of the breast in the United States between 1973 and 1992 and to estimate total numbers of in situ cases diagnosed and numbers treated by mastectomy since 1983, when screening mammography for breast cancer began to become widespread.

DESIGN

Analysis of population-based breast cancer incidence data collected by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program since 1973 and treatment data collected by the SEER program since 1983.

STUDY POPULATION

All women in the geographic areas af the United States included in the SEER program.

MAIN OUTCOME MEASURES

Annual age-adjusted and age-specific incidence rates for DCIS; time trends in distribution of cases by type of treatment; percentage of cases treated by mastectomy by geographic area; and estimated numbers for the entire United States of DCIS cases, mastectomies for DCIS, and cases attributable to mammography.

RESULTS

There was a marked increase in DCIS incidence beginning in the early 1980s. Average annual increases in rates between 1973 and 1983 and between 1983 and 1992 changed from 0.3% to 12.0% among women aged 30 to 39 years, from 0.4% to 17.4% among women aged 40 to 49, and from 5.2% to 18.1% among women aged 50 years or older. The total estimated number of DCIS cases in the United States in 1992 (23,368) was 200% higher than expected based on 1983 rates and trends between 1973 and 1983. Between 1983 and 1992, there was a marked decline in the proportion of DCIS cases treated by mastectomy (from 71% to 43.8%) and an increase in those treated by lumpectomy (from 25.6% to 53.3%). In 1992, 23.3% of cases were treated by lumpectomy and radiation, 30.2% by lumpectomy alone, and 2.6% with no surgery. Treatment patterns varied substantially by geographic area, with 57.7% of cases in New Mexico treated by mastectomy in 1992 compared with 28.8% in Connecticut. Despite the decline in the proportion of cases treated by mastectomy, the increased DCIS incidence rates resulted in an increase in the absolute number of cases treated by mastectomy until 1990 (n=10,657); in 1992, there were an estimated 10,242 DCIS cases treated by mastectomy.

CONCLUSIONS

Incidence rates of DCIS of the breast have increased dramatically since 1983. This increase correlates with the widespread adoption of modern mammographic screening. While early detection of invasive breast cancer is beneficial, the value of DCIS detection is currently unknown. There is cause for concern about the large number of DCIS cases that are being diagnosed as a consequence of screening mammography, most of which are treated by some form of surgery. In addition, the proportion of cases treated by mastectomy may be inappropriately high, particularly in some areas of the United States.