Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

Comparison of memory fMRI response among normal, MCI, and Alzheimer's patients

OBJECTIVE

To determine whether an fMRI memory encoding task distinguishes among cognitively normal elderly individuals, patients with mild cognitive impairment (MCI), and patients with early Alzheimer's disease (AD).

METHODS

Twenty-nine subjects (11 normal, 9 MCI, 9 AD) were studied with an fMRI memory encoding task. A passive sensory task was also performed to assess potential intergroup differences in fMRI responsiveness. Activation in the medial temporal lobe for the memory task and in the anatomic rolandic area for the sensory task was studied. Intergroup comparisons were performed using receiver operating characteristic (ROC) analyses. The ROC method provides rigorous control of artifactual false-positive "activation." Subjects were tested for recall and recognition of the encoding task stimuli following the fMRI study.

RESULTS

Medial temporal lobe activation was greater in normal subjects than MCI and AD patients (p = 0.03 and p = 0.04). There was no difference between AD and MCI patients in fMRI memory performance [corrected]. There was an association between fMRI memory activation (area under the ROC curve) and post-fMRI performance on recognition and free recall. There was no difference among the three groups on the sensory task.

CONCLUSIONS

MCI and AD patients had less medial temporal lobe activation on the memory task than the normal subjects but similar activation as normal subjects on the sensory task. These findings suggest decreased medial temporal activation may be a specific marker of limbic dysfunction due to the neurodegenerative changes of AD. In addition, fMRI is sufficiently sensitive to detect changes in the prodromal, MCI, phase of the disease.

Mortality from Creutzfeldt-Jakob disease and related disorders in Europe, Australia, and Canada

BACKGROUND

An international study of the epidemiologic characteristics of Creutzfeldt-Jakob disease (CJD) was established in 1993 and included national registries in France, Germany, Italy, the Netherlands, Slovakia, and the United Kingdom. In 1997, the study was extended to Australia, Austria, Canada, Spain, and Switzerland.

METHODS

Data were pooled from all participating countries for the years 1993 to 2002 and included deaths from definite or probable CJD of all etiologic subtypes.

RESULTS

Four thousand four hundred forty-one cases were available for analysis and included 3,720 cases of sporadic CJD, 455 genetic cases, 138 iatrogenic cases, and 128 variant cases. The overall annual mortality rate between 1999 and 2002 was 1.67 per million for all cases and 1.39 per million for sporadic CJD. Mortality rates were similar in all countries. There was heterogeneity in the distribution of cases by etiologic subtype with an excess of genetic cases in Italy and Slovakia, of iatrogenic cases in France and the UK, and of variant CJD in the UK.

CONCLUSIONS

This study has established overall epidemiologic characteristics for Creutzfeldt-Jakob disease (CJD) of all types in a multinational population-based study. Intercountry comparisons did not suggest any relative change in the characteristics of sporadic CJD in the United Kingdom, and the evidence in this study does not suggest the occurrence of a novel form of human bovine spongiform encephalopathy infection other than variant CJD. However, this remains a possibility, and countries currently unaffected by variant CJD may yet have cases.

Safety study of nonoxynol-9 as a vaginal microbicide: evidence of adverse effects

Nonoxynol-9 (N-9) is virucidal in vitro, and is therefore a candidate microbicide for preventing sexual transmission of HIV. However, the activity of N-9 is nonspecific, suggesting that virucidal levels may produce adverse effects including epithelial disruption, inflammation of the genital mucosa, or both. A randomized placebo controlled trial of daily use of 100 mg of N-9 took place for 1 week in 40 female volunteers. Outcome measures included symptoms, colposcopic and histologic changes in the genital tract, and impact on vaginal flora. Genital irritation was reported by 10 of the N-9 and 5 of the placebo group. Colposcopy showed erythema in 9 of the N-9 group and 2 of the placebo group. Histologic inflammation was found in 7 of the N-9 group and 2 of the placebo group. Inflammatory changes were characterized by patchy infiltration of the lamina propria predominantly with CD8+ lymphocytes and macrophages, in the absence of epithelial disruption. A transient reduction in numbers of lactobacilli was observed in 9 of the 15 women using N-9, and 6 of 18 women using placebo. N-9 used for 7 days in a standard spermicidal dose was associated with increased irritation, colposcopic and histologic evidence of inflammation and was more frequently associated with reduction in numbers of lactobacilli during gel use. The clinical significance of the recruitment of cells susceptible to HIV infection to the genital mucosa is unknown but raises concerns about the suitability of N-9 as a microbicide when given in this dose.

Epidemics of syphilis in the Russian Federation: trends, origins, and priorities for control

After continuous decline throughout the 1980s, surveillance-defined estimates of the incidence of syphilis in Russia have shown a rapid and substantial increase during the 1990s. The reasons for this epidemic are unclear, but must be sought among changes both in sexual behaviour and in the patterns of provision, use, and effectiveness of diagnostic, treatment, and contact tracing services. High incidence of sexually transmitted disease causes correspondingly high levels of morbidity and suffering as well as significant health-care and other economic costs. Our current understanding suggests that the transmissibility of HIV is increased by infection with sexually transmitted disease. The syphilis epidemic together with changes in sexual behaviour, increased travel and migration, and rapid increases in injecting drug use may create the conditions for an epidemic of sexually acquired HIV infection in Russia that substantially outstrips those encountered in most Western European countries.

Sexualized drug use ('chemsex') and high-risk sexual behaviours in HIV-positive men who have sex with men

Objectives

The incidence of sexually transmitted infections (STIs) and HIV infection remains high in gay, bisexual, and other men who have sex with men (MSM) in the UK, and sexualized drug use (“chemsex”) and injecting drug use (“slamsex”) may play a part in this. We aimed to characterize HIV‐positive MSM engaging in chemsex/slamsex and to assess the associations with self‐reported STI diagnoses and sexual behaviours.

Methods

Data from a 2014 survey of people attending HIV clinics in England and Wales were linked to clinical data from national HIV surveillance records and weighted to be nationally representative. Multivariable logistic regression assessed the associations of chemsex and slamsex with self‐reported unprotected anal intercourse (UAI), serodiscordant UAI (sdUAI) (i.e. UAI with an HIV‐negative or unknown HIV status partner), sdUAI with a detectable viral load (>50 HIV‐1 RNA copies/mL), hepatitis C, and bacterial STIs.

Results

In the previous year, 29.5% of 392 sexually active participants engaged in chemsex, and 10.1% in slamsex. Chemsex was significantly associated with increased odds of UAI [adjusted odds ratio (AOR) 5.73; P < 0.001], sdUAI (AOR 2.34; P < 0.05), sdUAI with a detectable viral load (AOR 3.86; P < 0.01), hepatitis C (AOR 6.58; P < 0.01), and bacterial STI diagnosis (AOR 2.65; P < 0.01). Slamsex was associated with increased odds of UAI (AOR 6.11; P < 0.05), hepatitis C (AOR 9.39; P < 0.001), and bacterial STI diagnosis (AOR 6.11; P < 0.001).

Conclusions

Three in ten sexually active HIV‐positive MSM engaged in chemsex in the past year, which was positively associated with self‐reported depression/anxiety, smoking, nonsexual drug use, risky sexual behaviours, STIs, and hepatitis C. Chemsex may therefore play a role in the ongoing HIV and STI epidemics in the UK.

A novel multi-domain mucin-like glycoprotein of Cryptosporidium parvum mediates invasion

Cryptosporidium parvum is a protozoan parasite which produces self-limited disease in immunocompetent hosts and devastating, persistent diarrhea in immunocompromised individuals. There is no effective treatment for cryptosporidiosis and little is known about the basic biology of the organism. Cloning and sequence analysis of the gene encoding GP900, a previously identified > 900 kDa glycoprotein, predicts a mucin-like glycoprotein composed of distal cysteine-rich domains separated by polythreonine domains and a large membrane proximal N-glycosylated core region. A trinucleotide repeat composed predominantly of the triplet ACA encodes the threonine domains. GP900 is stored in micronemes prior to appearance on the surface of invasive forms. The concentration of native GP900 which inhibits 50% (IC50) of invasion in vitro is low picomolar; the IC50 for a recombinant cysteine rich-domain is low nanomolar. These observations indicate that GP900 is a parasite ligand for a host receptor involved in attachment/invasion and suggest that immunotherapy or chemotherapy directed against GP900 may be feasible.

Prospective multiaxial motion correction for fMRI

Corruption of the image time series due to interimage head motion limits the clinical utility of functional MRI. This paper presents a method for real-time prospective correction of rotation and translation in all six degrees of rigid body motion. By incorporating an orbital navigator (ONAV) echo for each of the sagittal, axial, and coronal planes into the fMRI pulse sequence, rotation and translation can be measured and the spatial orientation of the image acquisition sequence that follows can be corrected prospectively in as little as 160 msec. Testing of the method using a computerized motion phantom capable of performing complex multiaxial motion showed subdegree rotational and submillimeter translational accuracy over a range of +/-8 degrees and +/-8 mm of motion. In vivo images demonstrate correction of simultaneous through-plane and in-plane motion and improved detection of fMRI activation in the presence of head motion.

Mineralization of the deep gray matter with age: a retrospective review with susceptibility-weighted MR imaging

BACKGROUND AND PURPOSE

Susceptibility-weighted imaging (SWI) is an advanced MR imaging sequence that can be implemented at high resolution. This sequence can be performed on conventional MR imaging scanners and is very sensitive to mineralization. The purpose of this study was to establish the course of mineralization in the deep gray matter with age by using SWI.

MATERIALS AND METHODS

We retrospectively reviewed susceptibility-weighted images of 134 patients (age range, 1 to 88 years). Inclusion criteria comprised a normal conventional MR imaging (T1, T2, and fluid-attenuated inversion recovery sequences). We statistically analyzed the relative signal intensities of the globus pallidus, putamen, substantia nigra, caudate nucleus, red nucleus, and thalamus for correlation with age. The putamen was graded according to a modified scale, based on previous work that described a systematic pattern of mineralization with age. Bands of hypointensity in the globus pallidus, dubbed "waves," were also evaluated.

RESULTS

We documented decreasing intensity (ie, increasing mineralization) with age in all deep gray matter areas analyzed. We confirmed the age-related posterolateral to anteromedial progression of mineralization in the putamen. Characteristic medial and lateral bands of mineralization were exhibited in the globus pallidus in all children and young adults older than 3 years. Finally, an increase in the number of "waves" present in the globus pallidus was associated with increased age by category.

CONCLUSION

This study documents the course and pattern of mineralization in the deep gray matter with age, as determined by SWI. These findings may play a role in evaluating diseased brains in the future.

Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s^{-2}/sqrt[Hz], or (0.54±0.01)×10^{-15}  g/sqrt[Hz], with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/sqrt[Hz], about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s^{-2}/sqrt[Hz] down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

Health seeking behaviour and the control of sexually transmitted disease

What people do when they have symptoms or suspicion of a sexually transmitted disease (STD) has major implications for transmission and, consequently, for disease control. Delays in seeking and obtaining diagnosis and treatment can allow for continued transmission and the greater probability of adverse sequelae. An understanding of health seeking behaviour is therefore important if STD control programmes are to be effective. However, taboos and stigma related to sex and STD in most cultures mean that gaining a true picture is difficult and requires considerable cultural sensitivity. At the moment relatively little is known about who people turn to for advice, or about how symptoms are perceived, recognized or related to decisions to seek help. It is argued that such knowledge would assist programme planners in the development of more accessible and effective services, that studies of health seeking behaviour need to include a combination of qualitative and quantitative methods, and that studies should include data collection about people who do not present to health care facilities as well as those who do. A pilot protocol for studying STD-related health seeking behaviour in developing countries is briefly presented.

The cost of multiple drug resistance in Pseudomonas aeruginosa

The spread of bacterial antibiotic resistance mutations is thought to be constrained by their pleiotropic fitness costs. Here we investigate the fitness costs of resistance in the context of the evolution of multiple drug resistance (MDR), by measuring the cost of acquiring streptomycin resistance mutations (StrepR) in independent strains of the bacterium Pseudomonas aeruginosa carrying different rifampicin resistance (RifR) mutations. In the absence of antibiotics, StrepR mutations are associated with similar fitness costs in different RifR genetic backgrounds. The cost of StrepR mutations is greater in a rifampicin-sensitive (RifS) background, directly demonstrating antagonistic epistasis between resistance mutations. In the presence of rifampicin, StrepR mutations have contrasting effects in different RifR backgrounds: StrepR mutations have no detectable costs in some RifR backgrounds and massive fitness costs in others. Our results clearly demonstrate the importance of epistasis and genotype-by-environment interactions for the evolution of MDR.

Geographical distribution of variant Creutzfeldt-Jakob disease in Great Britain, 1994-2000

BACKGROUND

Geographical variation in the distribution of variant Creutzfeldt-Jakob disease (vCJD) might indicate the transmission route of the infectious agent to man. We investigated whether regional incidences of vCJD were correlated with regional dietary data.

METHODS

The National CJD Surveillance Unit prospectively identified 84 people with vCJD up to Nov 10, 2000, in Great Britain. Their lifetime residential histories were obtained by interviews with a close relative. Cumulative incidences of vCJD by standard region were calculated. Grid references for places of residence in 1991 were identified and evidence of geographical clusters were sought. Data on diet in the 1980s were analysed for regional correlations with vCJD incidence. The socioeconomic status of the places of residence of people with vCJD was compared with that of the general population.

FINDINGS

vCJD incidence was higher in the north of Great Britain than the south. The rate ratio (north vs south) was 1.94 (95% CI 1.27-2.98). The mean Carstairs' deprivation score for areas of residence of people with vCJD was -0.09 (-0.73 to 0.55), which is close to the national average of zero. Regional rates of vCJD were correlated with consumption of other meat or meat products as classified and recorded by the Household Food Consumption and Expenditure Survey (r=0.72), but not with data from the Dietary and Nutritional Survey of British Adults. Five people with vCJD in Leicestershire formed a cluster (p=0.004).

INTERPRETATION

Regional differences in vCJD incidence are unlikely to be due to ascertainment bias. We had difficulty determining whether regional variations in diet might cause these differences, since the results of dietary analyses were inconsistent.

Cutaneous hemangiosarcoma in 25 dogs: a retrospective study

Hemangiosarcomas confined to the skin and underlying muscle were surgically excised in 25 dogs. Tumors were staged based on their histological location (ie, dermal, hypodermal, and deep). Dermal (stage I) hemangiosarcomas were small, most commonly ventral-abdominal or prepucial in location, and were associated with prolonged survival times (median survival, 780 days). Tumors with hypodermal (stage II) and underlying muscular involvement (stage III) were grouped together because of their larger size, bruise-like appearance, lack of anatomic predilection, biological behavior, and shorter survival times (median survival of 172 and 307 days for dogs with stages II and III, respectively). We conclude that dermal hemangiosarcomas may be effectively treated with surgery alone, whereas hemangiosarcomas located within the hypodermal tissues bear a poor prognosis and warrant wide surgical excision with adjuvant chemotherapy.

Risky business: health and safety in the sex industry over a 9 year period

OBJECTIVES

To assess whether a previously established low sexually transmitted infection/HIV risk in prostitutes in London has been sustained, and to measure other occupational risks, including mortality.

DESIGN

9 year prospective study in west London.

SUBJECTS

402 prostitutes recruited from 1985 to 1991, 320 were followed up for 675 person years to 1994.

MAIN OUTCOME MEASURES

Condom use in commercial and non-commercial sex; viral and bacterial sexually transmitted infection at initial and follow up visits; death.

RESULTS

Condom use increased significantly from 1986 to 1993 and protected the majority of commercial sexual contacts. Baseline prevalence: HIV 1.3%, hepatitis C 6.7%, hepatitis B 6.6%, syphilis 2.3%, HTLV-I/II 0.4%, gonorrhoea 3.0%, chlamydia 8.2%, genital herpes 16.8%. Incidence (per 100 person years): HIV 0.2, hepatitis C 0.3, gonorrhoea 5.6, chlamydia 12.6, genital herpes 6.5. Viral infections were associated with injecting drug use and non-British nationality; bacterial infections were associated with numbers of non-commercial partners but not with sexual contacts at work. Four women died during the course of the study; two had AIDS, two were murdered. This mortality of 5.93 per 1000 person years was 12 times the expected rate for women of a similar age.

CONCLUSIONS

This study shows that it is possible to have a larger number of sexual partners and remain free from sexually transmitted infections provided that condoms are used consistently: there has been a sustained increase in condom use in the sex industry. None the less, prostitutes are at increased risk of sexually transmitted infections, primarily through non-commercial sexual partnerships. Infectious diseases are only one of the risks facing prostitutes, as illustrated by the mortality from violence as well as from HIV infection.

The prevalence of lymphogranuloma venereum infection in men who have sex with men: results of a multicentre case finding study

Objective:

To determine the prevalence of lymphogranuloma venereum (LGV) and non-LGV associated serovars of urethral and rectal Chlamydia trachomatis (CT) infection in men who have sex with men (MSM).

Design:

Multicentre cross-sectional survey.

Setting:

Four genitourinary medicine clinics in the United Kingdom from 2006–7.

Subjects:

4825 urethral and 6778 rectal samples from consecutive MSM attending for sexual health screening.

Methods:

Urethral swabs or urine and rectal swabs were tested for CT using standard nucleic acid amplification tests. Chlamydia-positive specimens were sent to the reference laboratory for serovar determination.

Main outcome:

Positivity for both LGV and non-LGV associated CT serovars; proportion of cases that were symptomatic.

Results:

The positivity (with 95% confidence intervals) in rectal samples was 6.06% (5.51% to 6.66%) for non-LGV CT and 0.90% (0.69% to 1.16%) for LGV; for urethral samples 3.21% (2.74% to 3.76%) for non-LGV CT and 0.04% (0.01% to 0.16%) for LGV. The majority of LGV was symptomatic (95% of rectal, one of two urethral cases); non-LGV chlamydia was mostly symptomatic in the urethra (68%) but not in the rectum (16%).

Conclusions:

Chlamydial infections are common in MSM attending for sexual health screening, and the majority are non-LGV associated serovars. We did not identify a large reservoir of asymptomatic LGV in the rectum or urethra. Testing for chlamydia from the rectum and urethra should be included for MSM requesting a sexual health screen, but serovar-typing is not indicated in the absence of symptoms. We have yet to identify the source of most cases of LGV in the UK.

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5<p(T)<12 GeV/c. The collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

Effect on normal vaginal flora of three intravaginal microbicidal agents potentially active against human immunodeficiency virus type 1

The effect on normal vaginal flora of three intravaginal microbicides potentially active against human immunodeficiency virus type 1 was examined. Volunteers received dextrin sulfate (D2S), nonoxynol-9 (N-9), or docusate sodium in separate placebo-controlled studies. High vaginal swabs were obtained for bacterial culture before and after microbicide application. D2S did not affect the vaginal flora. However, lactobacilli decreased by > or = 10(2) cfu/mL in 9 (56%) of 16 women given N-9 and in 5 (63%) of 8 women given docusate sodium. Women using N-9 were also significantly more likely to become colonized abnormally (usually with aerobic gram-negative rods) than were those using placebo, as were women using docusate sodium. Women with reduced lactobacilli were less likely to regain normal flora than were those whose lactobacilli were unaffected. However, coliform colonization occurred whether lactobacilli produced H2O2 or not. Continuous use of N-9 could induce susceptibility to urinary and gynecological infection. It is essential that potential microbicides are examined for activity against normal vaginal flora.

Purification and chemical characterisation of membrane glycoproteins from rat thymocytes and brain, recognised by monoclonal antibody MRC OX 2

The MRC OX 2 monoclonal antibody recognises antigens present on rat thymocytes, brain, follicular dendritic cells in lymphoid organs, vascular endothelium, some smooth muscle and B-lymphocytes. The OX 2 antigens recognised by this antibody were purified from brain and thymus, by solubilisation with sodium deoxycholate, affinity chromatography with MRC OX 2 antibody and gel filtration. The purified brain and thymocyte OX 2 antigens were glycoproteins with apparent Mr 41000 and 47000 respectively as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulphate. Rabbit antisera raised against the purified antigens were analysed by radioimmunoassay and immunoperoxidase-staining of tissue sections. The brain and thymocyte OX 2 antigens were antigenically very similar to those on the other tissues. This indicates that the unusual pattern of distribution was not the result of fortuitous cross-reaction of the MRC OX 2 antibody, as the rabbit sera would be expected to recognise more determinants on the antigen than that recognised by the monoclonal antibody. The amino acid compositions of brain and thymus OX 2 antigens were very similar but with no distinguishing features. Carbohydrate compositions showed that the OX 2 antigens were highly glycosylated, with brain OX 2 antigen containing 24% and thymocyte OX 2 antigen 33% by weight of carbohydrate. Both OX 2 antigens contained carbohydrate residues typical of structures N-linked to asparagine but lacked galactosamine, indicating the absence of O-linked structures. Thymocyte OX 2 contained higher levels of galactose and sialic acid but less fucose than brain OX 2. Similar differences had been observed for brain and thymocyte Thy-1 antigens and were also observed in pooled glycoproteins purified by lentil affinity chromatography from these tissues, reflecting overall differences in the patterns of glycosylation in the two tissues. The OX 2 antigens showed many similarities to Thy-1 antigens in their odd patterns of distribution, characteristic migration on polyacrylamide gels in sodium dodecyl sulphate, and carbohydrate compositions. It is possible that OX 2 antigens, like Thy-1 antigens, have homologies with immunoglobulin domains. A possible role for OX 2 antigens in cell interactions necessary for tissue organisation is discussed.

Lectin activation in Giardia lamblia by host protease: a novel host-parasite interaction

A lectin in Giardia lamblia was activated by secretions from the human duodenum, the environment where the parasite lives. Incubation of the secretions with trypsin inhibitors prevented the appearance of lectin activity, implicating proteases as the activating agent. Accordingly, lectin activation was also produced by crystalline trypsin and Pronase; other proteases tested were ineffective. When activated, the lectin agglutinated intestinal cells to which the parasite adheres in vivo. The lectin was most specific to mannose-6-phosphate and apparently was bound to the plasma membrane. Activation of a parasite lectin by a host protease represents a novel mechanism of host-parasite interaction and may contribute to the affinity of Giardia lamblia to the infection site.

Centrality dependence of high-p(T) hadron suppression in Au+Au collisions at sqrt[s(NN)]=130 GeV

Inclusive transverse momentum distributions of charged hadrons within 0.2<p(T)<6.0 GeV/c have been measured over a broad range of centrality for Au+Au collisions at sqrt[s(NN)]=130 GeV. Hadron yields are suppressed at high p(T) in central collisions relative to peripheral collisions and to a nucleon-nucleon reference scaled for collision geometry. Peripheral collisions are not suppressed relative to the nucleon-nucleon reference. The suppression varies continuously at intermediate centralities. The results indicate significant nuclear medium effects on high-p(T) hadron production in heavy-ion collisions at high energy.

Who pays for sex? An analysis of the increasing prevalence of female commercial sex contacts among men in Britain

BACKGROUND

In the United Kingdom the incidence of sexually transmitted infections (STI) and risky sexual behaviours is increasing. The role of commercial sex in this trend is poorly understood. Little is known about the men who pay for sex. We examined the epidemiology of female commercial sex contacts reported by men in 1990 and 2000.

METHODS

National probability sample surveys of sexual attitudes and lifestyles (Natsal) of men aged 16-44 resident in Britain in 1990 (n = 6000) and 2000 (n = 4762).

RESULTS

The proportion of men who reported paying women for sex in the previous 5 years increased from 2.0% (95% CI 1.6 to 2.5) in 1990 to 4.2% in 2000 (95% CI 3.6 to 4.9). In both surveys, paying for sex was more frequent in men aged between 25 years and 34 years, who were never or previously married, and who lived in London. There was no association with ethnicity, social class, homosexual contact, or injecting drug use. Men who paid for sex were more likely to report 10 or more sexual partners in the previous 5 years; only a minority of their lifetime sexual partners (19.3%) were commercial. They were more likely to meet partners abroad and to report previous STI. Only 15% reported having had an HIV test.

CONCLUSION

The proportion of men who reported paying for heterosexual sex has increased, and these men have multiple commercial and non-commercial partners. Their higher rates of STI and low level of HIV testing suggest the need for prevention interventions for clients as well as sex workers.

Killing of Giardia lamblia by human milk lipases: an effect mediated by lipolysis of milk lipids

Killing of Giardia lamblia by fresh human milk requires the presence of bile salt, a known activator of bile salt-stimulated lipase, the major lipase in human milk. Purified enzyme did not kill the parasite even in the presence of activator unless milk lipids were also present in the reaction mixture. Free fatty acids had a marked giardiacidal effect, a phenomenon supporting the view that fatty acids, released during hydrolysis of milk triglycerides, are responsible for the killing of G. lamblia by human milk. Bile salt-independent lipolysis took place in milk during storage at 4 C. This lipolysis correlated strongly with activity of lipoprotein lipase, also present in human milk. During such storage, raw human as well as bovine milk developed giardiacidal activity that could be prevented by inactivation or inhibition of the milk lipases by pasteurization or addition of eserine to the milk, respectively, before storage.