Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs

A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A_{LU}^{sinϕ_{R}} moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.

Precision Measurement of the p(e,e^{'}p)π^{0} Reaction at Threshold

New results are reported from a measurement of π^{0} electroproduction near threshold using the p(e,e^{'}p)π^{0} reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ_{π}^{*} and θ_{π}^{*} angles in the pπ^{0} center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q^{2} coverage ranges from 0.05 to 0.155 (GeV/c)^{2} in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q^{2}>0.07 (GeV/c)^{2}, while the s-wave predictions are in reasonable agreement.

Susceptibility of Peruvian mosquitoes to eastern equine encephalitis virus

Mosquitoes were collected in the Amazon Basin, near Iquitos, Peru, and used in experimental studies to evaluate their susceptibility to strains of eastern equine encephalitis virus (EEEV) that were isolated from mosquitoes captured within 20 km of Iquitos. When fed on hamsters or chickens with a viremia of 4105 plaque-forming units (PFU) of EEEV/ml, Culex pedroi Sirivanakarn and Belkin, Aedesfulvus (Wiedemann), Psorophora albigenu (Peryassu), and Psorophoraferox (Von Humboldt) were susceptible to infection, whereas none of the Aedes serratus (Theobald), Culex vomerifer Komp, Culex gnomatos Sallum, Huchings, and Ferreira, Culex portesi Senevet and Abonnenc, or Culex coronator Dyar and Knab became infected, even though they fed on the same viremic blood sources. When these mosquito species fed on animals with viremias of approximately 10(8) PFU/ml, Cx. pedroi, Ae.II (Brazil-Peru) and a lineage III (Argentina-Panama) isolate of EEEV. This study, combined with the repeated isolation of strains of EEEV from Cx. pedroi captured in the Amazon Basin region of Peru, suggests that Cx. pedroi may be the primary enzootic vector of EEEV in this region.

Automated classification of crystallization experiments using wavelets and statistical texture characterization techniques

A method is presented for the classification of protein crystallization images based on image decomposition using the wavelet transform. The distribution of wavelet coefficient values in each sub-band image is modelled by a generalized Gaussian distribution to provide discriminatory variables. These statistical descriptors, together with second-order statistics obtained from joint probability distributions, are used with learning vector quantization to classify protein crystallization images.

Review article: is clinical remission the optimum therapeutic goal in the treatment of Crohn's disease?

Currently, the therapeutic end-point in the treatment of Crohn's disease is the remission of symptoms, but recent data confirm that mucosal inflammation may continue in the absence of symptoms. Furthermore, emerging evidence indicates that such subtle, sub-clinical mucosal inflammation leads to clinical relapse. The assessment of mucosal inflammation has become easier with the availability of faecal calprotectin assay. Current anti-inflammatory therapy often leaves low-grade mucosal inflammation untreated, and therefore recurrent relapses occur. We need to investigate whether the therapeutic end-point of anti-inflammatory medications needs to be more rigorous and to aim at complete mucosal healing, confirmed by the normalization of mucosal inflammatory markers such as faecal calprotectin concentrations. Immunosuppressive therapy with azathioprine/ 6-mercaptopurine currently offers the best mucosal healing treatment with reduction of relapses, but newer biological agents might offer less toxic therapy. Clinical trials to test the feasibility and efficacy of such a paradigm shift in the medical management of Crohn's disease are now warranted.

Management of gastrointestinal haemorrhage

A variety of endoscopic haemostatic techniques have enabled major advances in the management of not only bleeding peptic ulcers and bleeding varices, but also in a variety of bleeding lesions in the small intestine and in the colon. Indeed, the development and widespread implementation of endoscopic haemostasis has been one of the most important developments in clinical gastroenterology in the past two decades. An increasingly ageing cohort of patients with multiple co-morbidity are being treated and therefore improving the outcome of gastrointestinal bleeding continues to pose major challenges.

Geriatricians health survey 2000

OBJECTIVES

To characterize geriatricians' preventive health behaviors including vitamin/supplement use, exercise, smoking, alcohol use, and weight control.

DESIGN

Mailed questionnaire.

SETTING

United States.

PARTICIPANTS

Two thousand six hundred eleven U.S. physicians certified as having added qualifications in geriatric medicine and who were members in the American Geriatrics Society; 1,524 returned completed questionnaires (58%).

MEASUREMENTS

Rates of supplement use and recommendations, preventive health visits, advance directive completion, exercise, religious service attendance, smoking, alcohol use, and amount of adult weight gain.

RESULTS

Most responding geriatricians took at least one vitamin supplement: 50% vitamin E, 50% a multivitamin (MVI), and 31% vitamin C. Calcium ingestion was common among women. Other supplement use was uncommon: ginkgo compounds were consumed by 47 (3%), and 77 (5%) took a variety of other nonvitamin supplements. Over 90% recommended vitamins, especially multivitamins and vitamin E, at least sometimes. Recommendations for ginkgo (38%) and St. John's wort (33%) were also common. Almost half of respondents had completed a formal advance directive. Exercise was practiced at least weekly by 88%. Cigarette smoking was rare (1%), but at least occasional alcohol use was common (85%). Most of respondents were men (74%), and 35% had completed fellowship training.

CONCLUSION

Vitamin/supplement use was common among responding geriatricians but not universal. Respondents often recommended MVI, vitamin E, and vitamin C, but were less likely to consume or recommend other supplements. The most common preventive health behavior among our respondents was exercise.

Dietary arginine alters time of symptom onset in Huntington's disease transgenic mice

Recent neuroimaging studies reported complex changes in cerebral blood flow (CBF) in early-staged Huntington's disease (HD) patients. Deckel and co-workers [Deckel and Duffy, Brain Res. (in press); Deckel and Cohen, Prog. Neuro-Psychopharmacol. Biol. Psychiatry 24 (2000) 193; Deckel et al., Neurology 51 (1998) 1576; Deckel et al., J. Nucl. Med. 41 (2000) 773] suggested that these findings might be accounted for, in part, by alterations in cerebral nitric oxide (NO) and its byproduct, peroxynitrite. The current experiment tested this hypothesis by altering NO levels via manipulations of dietary L-arginine (ARG), the dietary precursor of NO, in mice transgenic for HD. Seventy-one mice were assigned at 12 weeks of age to one of three isocaloric diets that varied in their content of ARG. These diets included: (a) 0% ARG, (b) 1.2% ARG (i.e. typical mouse chow), or (c) 5% ARG. The 5% ARG diets in HD mice accelerated the time of onset of body weight loss (P<0.05) and motor impairments (P<0.05), and increased resting CBF in HD relative to control (P<0.05). Conversely, the 0% ARG diet demonstrated no loss of body weight and had no changes in CBF relative to controls. However, the 0% ARG HD group continued to show significant deficits on motor testing (P<0. 05). The 1.2% ARG HD group showed reduced body weight loss, better motor functioning, and fewer changes in CBF compared to the 5% ARG HD group. Immunocytochemistry analysis found greater deposition of nitrotyrosine in the cortex, and vasculature, of HD+ mice, 5% and 1. 2%>0% arginine diets. When collapsed across all conditions, CBF inversely correlated (P<0.05) both with the body weight and motor changes suggesting that changes in CBF are associated with behavioral decline in HD mice. Collectively, these findings indicate that dietary consumption of the NO precursor ARG has a measurable, but complex, effect on symptom progression in HD transgenic mice, and implicates NO in the pathophysiology of HD.

Annotated checklist of the mosquito species encountered during arboviral studies in Iquitos, Peru (Diptera: Culicidae)

A checklist of the mosquito fauna encountered during arboviral studies in Iquitos, Peru, is presented. A total of 16 genera, 30 subgenera, and 96 species were identified, including 24 species reported from Peru for the 1st time. Notations on the taxonomy and biology for 28 species are also provided.

The Department of Defense laboratory-based global influenza surveillance system

Military global influenza surveillance began in 1976 as an Air Force program. In 1997, the Department of Defense (DoD) Global Emerging Infections Surveillance and Response System expanded the program to include all services. Also included were local residents in areas where DoD overseas research activities operated. This new, worldwide DoD surveillance infrastructure provides valuable information and can respond quickly to outbreaks. This was demonstrated during the current influenza season when a suspected outbreak was reported in Panama. In less than 3 weeks, specimens were collected, transported, and cultured, and isolates were subtyped and sent to the Centers for Disease Control and Prevention for further studies. This influenza surveillance initiative combines viral isolation, antigenic characterization, and molecular sequencing with clinical and public health management of information. The information obtained is shared with the Centers for Disease Control and Prevention and the World Health Organization and has contributed to important decisions in influenza vaccine composition.

Distinct patterns of glomerular disease in Lima, Peru

AIM

We performed both a retrospective and prospective study to elucidate the types of glomerular diseases present in adults in Lima, Peru.

MATERIAL AND METHODS

In the retrospective study, we analyzed 1,263 renal biopsies over a 10-year period (1985 -1995) that were processed at a central reference renal pathology laboratory in Lima. 101 cases were examined in the prospective study.

RESULTS

The most common glomerular diseases observed were those due to systemic lupus erythematosus (30.2%), membranoproliferative glomerulonephritis (MPGN, 14.8%), and focal and segmental glomerulosclerosis (FSGS, 13.9%). Although mesangial-proliferative nephritis was observed in 9.5% of cases, IgA nephropathy was rare (0.9%). Examination of the year to year frequency showed that MPGN has tended to decrease in frequency with time whereas FSGS has been increasing. Although there is known to be a high frequency of infections in Peru, only 4.2% of the cases in the retrospective study were associated with infection. Furthermore, in the prospective study, only one case of hepatitis C and no cases of hepatitis B viral infection were detected, including in the 11 cases of MPGN observed.

CONCLUSION

We conclude that the epidemiology of glomerular disease in Lima, Peru, is distinct from most areas of the world, but has similarities to certain regions in Africa, in that MPGN is common whereas IgA nephropathy appears to be rare. Further studies are necessary to elucidate the reasons why the patterns of glomerular disease are different from that observed in other parts of the world.

[STRONGYLOIDES STERCORALIS: CLINICAL SEVERE FORMS ASSOCIATED TO HTLV-1 INFECTION]

A study was conducted in Lima to determine the HTLV-1 infection rate among patients with different clinical patterns of Strongyloidiasis. This study included 21 patients with Strongyloides Stercoralis (St St) hyperinfection (Group 1), and a group which consisted of sex and age matched asymptomatic healthy individuals whose stools were negative (Control Group Group 2). A third group included 33 patients with "probable hyperinfection", and another group of 63 patients with intestinal Strongyloidiasis, without evidence of systemic disease, was included. Serum from each studied individual was analized to find HTLV-1/II and ELISA; positive cases were confirmed by Western Blot. The hyperinfection rate was significantly higher [85.7% (18/21)] compared to the control group [4.7% (1/21)] p<0.001. Likewise, the "probable hyperinfection" group was considerably higher [69.7% (23/33)] in comparison to the control group p<0.01. The group with intestinal Strongyloidiasis was [10% (6/62)] lower than patients with Strongyloides hyperinfection, but did not differ significantly (p>0.05) from the control group. In this last group 3/6 were HTLV-1 positive, and their follow-up showed they developed hyperinfection forms. We conclude that severe forms of St St are considerably associated to HTLV-1 infection in adults and children over 5 years of age. No cases with HTLV-II were detected.

Passive transfer of growth-inhibitory antibodies raised against yeast-expressed recombinant Plasmodium falciparum merozoite surface protein-1(19)

Purified rabbit immunoglobulin raised against yeast-expressed recombinant FVO or 3D7 Plasmodium falciparum merozoite surface protein-1 (MSP-1) 19k-D C terminal fragment (MSP-1(19)) was transfused into malaria-naive Aotus nancymai monkeys that were immediately challenged with FVO asexual stage malaria parasites. Control monkeys received rabbit immunoglobulin raised against the sexual stage antigen Pfs25 or Aotus hyperimmune serum obtained from monkeys immunized by P. falciparum infection and drug cure. Passive transfer of rabbit anti-MSP-1(19) failed to protect against homologous or heterologous challenge and, when compared with negative controls, there were no differences in prepatent periods or time to treatment. Interestingly, rabbit anti-MSP-1(19), but not anti-Pfs25, immunoglobulin, and immune monkey serum prevented the development of antibodies directed against MSP-1(19) fragment by infected monkeys, indicating that the antibodies were reactive with native MSP-1(19) antigen in vivo. The prepatent period and time to treatment was greatly delayed in the two monkeys that received Aotus immune serum, both of which developed a chronic intermittent low level infection. In vitro parasite growth inhibition assays (GIAs) confirmed the presence of inhibitory activity (40% maximum inhibition) in concentrated anti-MSP-1(19) immunoglobulin (4.8 mg/ml), but the peak concentrations we achieved in vivo (1 mg/ml) were not inhibitory in vitro. Subinhibitory levels of anti-MSP-1(19) antibodies achieved by passive transfer were not protective against P. falciparum challenge.

Evidence for a post-Columbian introduction of human T-cell lymphotropic virus [type I] [corrected] in Latin America

To investigate the origin and dissemination of human T-cell lymphotropic virus type I in Latin America, we performed phylogenetic analysis on the LTR and env sequences of 13 HTLV-I isolates from Peruvians of four different ethnic groups: blacks and some mulattos of African origin; Quechuas of Inca origin; Nikkei of Japanese descendance; and Mestizos, a mixed population of white and Indian origin. All Peruvian samples could be situated within the cosmopolitan subtype HTLV-Ia, yet one sample showed an indeterminate Western blot pattern, lacking reactivity towards the HTLV-I type specific MTA1 peptide. Within the LTR, we could confirm the previously reported subdivision into four subgroups--one big transcontinental clade A, a Japanese clade B, a West African/Caribbean clade C and a North African clade D--and we identified a new separate subgroup E of black Peruvian strains. The clustering of the Peruvian samples seemed to depend on the ethnic origin of the host. The largest heterogeneity was observed in the black Peruvian samples. The mitochondrial DNA type of one of these black Peruvian strains of subgroup E was identical to that of West African source populations of the slave trade. Both findings support the idea of multiple post-Columbian introductions of African HTLV-Ia strains into the black Latin American population. Additionally, a tight cluster of Nikkei and Japanese samples implied a separate and rather recent transmission of a Japanese lineage of HTLV-I into Peru. A well-supported cluster of Latin American strains (including Peruvian Quechuas and Colombian Amerindians) could be situated within the transcontinental group. Molecular clock analysis of the Latin American and Japanese clade resulted in an equal evolutionary rate for those strains. Along with the anthropologically documented peopling of the Americas, the analysis was more in favour of a recent (400 to 100 years ago) introduction of HTLV-Ia into the American continent rather than a Palaeolithic introduction.

Insult after injury: pressure ulcers in trauma patients

DESIGN

Nonexperimental-Descriptive.

SAMPLE

The inclusion criteria were trauma patients, ages 15 and older, who were hospitalized for > 2 days, and who did not have preexisting skin breakdown. A total of 148 consecutive trauma patients admitted to the study institution meeting the inclusion criteria were prospectively enrolled.

METHODS

Patients were assessed every 3 days for skin breakdown. Information on the patient's bed type, therapies, medical devices, and nutrition was collected. The Braden Scale for predicting pressure ulcer risk was completed at each assessment.

FINDINGS

Of the 148 patients enrolled, 30 developed at least one area of skin breakdown for a prevalence of 20.3% in patients hospitalized more than 2 days. The most common cause of breakdown was positional pressure (47.4%). Cervical collars were the second leading cause at 23.7%, followed by tracheostomy/endotracheal tubes at 10.5%. The mobility subscale of the Braden Pressure Ulcer Risk Assessment tool was significantly predictive of skin breakdown (p < .001).

IMPLICATIONS FOR NURSING RESEARCH

Skin breakdown is a significant problem in trauma patients who are hospitalized for more than 2 days. Aggressive protocols on positioning, cervical collar use, and airway adjuncts, as well as additional active nursing interventions for immobile patients, may be ways to decrease the skin breakdown prevalence in this population.

Distortion compensation and elimination in holographic reconstruction

We discuss the quantitative location of objects from holographic images when the reconstruction wavelength differs from the recording wavelength. The holographic image equations are interpreted in a way that clarifies the meaning of stereo pairs of holographic images and indicates how backprojection methods can be used in holography to locate objects. Alternative methods involving the production of distortion-free regions in the holographic image field during reconstruction, the use of self-calibrating objects in the object field during recording, and triangulation can be used to locate objects.

The treatment of severe self-injurious behavior by the systematic fading of restraints: effects on self-injury, self-restraint, adaptive behavior, and behavioral correlates of affect

Severe self-injurious behavior (SIB) in people with mental retardation is difficult to treat when dangerously frequent or intense responding rules out functional analysis and interventions that permit free responding. This situation is common when restrictive devices, such as straight arm splints, are used. In this study, the effects of introducing flexion into a straight-arm splint, on SIB, self-restraint, adaptive behavior, and behavioral correlates of affect were examined for three individuals with severe mental retardation. Using single-case design methodology, for two individuals self-injury was reduced to zero, while the overall level of restriction was also significantly reduced. From the observed behavioral correlates of affect, there was no evidence of an increase in negative affect with the introduction of the new splint and the fading procedure, but there was evidence of an increase in positive vocalizations. Engagement in activities and social contact were not affected by the introduction of the new splint. The reasons for a decrease in SIB with a corresponding decrease in restriction in the absence of any manipulation of contingencies for SIB are discussed, with particular reference to stimulus control.

Effect of a bicycle safety program and free bicycle helmet distribution on the use of bicycle helmets by elementary school children

OBJECTIVE

Each year in the United States, 300,000 children are treated in emergency departments for bicycle injuries; one third have head injuries. The purpose of this study was to determine the effectiveness of educational interventions and free helmet distribution in increasing the use of helmets by elementary school children.

METHODS

Self-report questionnaires on the use of bicycle helmets were used for students at two elementary schools (n = 1610). Testing was done both before and after the administration of a bicycle safety program and the distribution of free helmets. Pretest and posttest answers were then compared for changes in helmet use.

RESULTS

Helmet usage increased significantly after the bicycle safety program, from 38% to 46% overall (p < 0.005). Children who were given free helmets were significantly more likely to wear their helmets (61.4%) than children who already owned helmets (43.4%) (p > 0.016). Children who attended the school in which free helmets were distributed showed a significant increase in helmet use (p < 0.01), whereas those at the school that had a safety program alone did not show a significant increase (p > 0.17).

DISCUSSION

The results of this study suggest that bicycle safety programs and free helmet distribution may increase the consistent use of helmets in elementary school children.

Short report: evidence of worldwide transmission of hepatitis G virus

Hepatitis G virus (HGV) has been recently documented in the Americas, Europe, and Australia. Distinct risk populations from North Africa, South America, and Southeast Asia were screened for HGV, in addition to hepatitis B and C viruses. First time recognition of HGV is described from Egypt and Indonesia. Notable is the high proportion of HGV positive individuals among multiply transfused children, ranging from 24% of those sampled from Egypt to 32% in Indonesia. Also, data from Peru suggest the likely association of HGV infection with progressive liver disease. Hepatitis G virus should be considered a world-wide health concern.

Prevalence of human retroviral infection in Quillabamba and Cuzco, Peru: a new endemic area for human T cell lymphotropic virus type 1

An epidemiologic study was conducted to determine the prevalence of retroviral infections among people of Qucchua origin in Cuzco and Quillabamba, Peru. The study volunteers included individuals at low and at high risk for retroviral infections. Each volunteer was interviewed to obtain clinical and epidemiologic data, and to identify risk behaviors for infection. The serum was tested for human immunodeficiency virus type 1 (HIV-1) and human T cell lymphotropic virus types 1/2 (HTLV-1/2) by standard enzyme-linked immunosorbent and Western blot assays. Among a total of 370 volunteers enrolled in the study, 276 were women and 94 were men whose ages ranged between 15 and 49 years. Infection with HTLV-1 was demonstrated in 5.1% (19 of 370), and one of these, a homosexual, was also positive for HIV-1; none had HTLV-2. Overall, the rate of HTLV-1 infection was 5.3% (5 of 94) for males and 5% (14 of 276) for females. Among the low risk group of 211 healthy pregnant women, five (2.3%) were positive for HTLV-1. The rate of HTLV-1 infection in this group was significantly correlated with a history of dental surgery, as well as other surgical procedures, and a history of jaundice. Among the volunteers who practiced risk behavior(s) for retroviral infections, the positive rates for HTLV-1 were 13.7% (7 of 51) for female sex workers, 6.2% (3 of 48) for homosexuals and/or bisexuals, 8.5% (4 of 47) for patients with sexually transmitted diseases (STDs), and 0.0% (0 of 13) for promiscuous heterosexual males. In female sex workers. HTLV-1 infection was found to be significantly associated with age, a history of STDs or genital ulcers, sexual intercourse during menses, and vaginal douching (P < 0.05). A low prevalence of HIV-1 infection indicates that the virus has not yet spread significantly in these areas.

Tropical spastic paraparesis and HTLV-I infection: clinical and epidemiological study in Lima, Peru

A descriptive study was performed to investigate the epidemiology and clinical features of 50 patients with tropical spastic paraparesis (TSP) associated with HTLV-I infection acquired in Peru. Cases seen at two reference centers in Lima (Alexander von Humboldt Tropical Medicine Institute and Guillermo Almenara National Hospital) between August 1989 and December 1995 are reviewed. All patients had serologic evidence of infection with reactive ELISA tests for HTLV-I, confirmed by positive Western blot assays. The male-female ratio of cases was 1.0:1.78. The mean age at the time of diagnosis was 52.4 years (range: 29 to 73, SD:11.3). A considerable proportion of patients (68%) had lived in Andean regions: this basically due to their native places (48%) because only 8% of cases were referred from these regions. The mean duration of symptoms prior to diagnosis was 4.95 years (range 0.5-22 years). The clinical features at diagnosis included progressive spastic paraparesis (100%) associated with sphincter disturbances (77.7%), paresthesia (61.1%) or lumbar pain (44%). The functional status of all patients was impaired at the time of evaluation: 44.1% walked unaided with a 'scissors-like' gait, 38% used assist devices for walking, 10% used wheelchairs and 8% were bedridden.

Environmental factors and nutritional status of rural children

The nutritional status of school-aged children is a growing concern of health care professionals today. In collaboration with a Kellogg Project in the deep south, students from a large university school of nursing participated in a project to improve the nutritional status of rural school-aged children. The project goals focused on educating thd children about the U.S. Department of Agriculture (USDA) Food Guide Pyramid, reading nutritional labels and recognizing foods with high fat content, and the importance of exercise along with diet. The nursing students created a nutritional assessment tool to use with each child to determine their educational needs. The project involved lecture, interactive class discussion, and hands-on activities. Information from the assessment tool revealed that fast food and foods high in fat were the most popular with the children. After project completion, the posttest revealed an increase in cognitive knowledge of nutrition among all the children. In addition to this positive learning experience for the children, improving the health status of children in the community was an excellent educational opportunity for the nursing students.

Benchmarking: breakthrough results through structured analysis

Benchmarking is the continuous process of measuring processes, services and practices against the toughest competition, or against companies recognized as industry leaders, for the purpose of identifying and adopting best practices. To facilitate this process, the Hamilton Civic Hospitals has developed a series of benchmarking templates, loosely based on the "unified model" of quality. This article presents the templates and describes their application as part of a benchmarking feedback loop.

Epidemiology of Norwalk virus during an outbreak of acute gastroenteritis aboard a US aircraft carrier

A large outbreak of acute gastroenteritis occurred over a 5-week period aboard an aircraft carrier. The estimated cumulative attack rate was 13% among the 4,500-man crew. Eight percent of the crew sought medical attention, nearly all of whom missed 1 day or more of work. The risk of developing illness was 2 to 3 times greater for individuals living in more crowded sleeping quarters (> 50 persons per compartment). Occurrence of gastroenteritis was associated with a fourfold or more rise in Norwalk virus antibody levels, as measured by an enzyme-linked immunoassay utilizing a baculovirus expressed recombinant antigen. In addition, 27 nm Norwalk virus-like particles were visualized in two of six stools examined by immune electron microscopy. The presence of a low (< 1:50) or a high (> or = 1:6,400) pre-illness antibody level was associated with a lower incidence of illness. This investigation indicates that Norwalk virus can adversely impact operations of a military vessel and that crowding is a major risk factor in transmission.

DNA-binding induces a major structural transition in a type I methyltransferase

The type IC DNA methyltransferase M.EcoR124I is a complex multisubunit enzyme that recognizes the non-palindromic DNA sequence GAAN6RTCG. Small angle X-ray scattering has been used to investigate the solution structure of the methyltransferase and of complexes of the enzyme with unmethylated and hemimethylated 30 bp DNA duplexes containing the specific recognition sequence. A major change in the quaternary structure of the enzyme is observed following DNA binding, based on a decrease in the radius of gyration from 56 to 40 A and a reduction in the maximum dimension of the enzyme from 180 to 112 A. The structural transition observed is independent of the methylation state of the DNA. CD shows that there is no change in the secondary structure of the protein subunits when DNA is bound. In contrast, there is a large increase in the CD signal arising from the DNA, suggesting considerable structural distortion which may allow access to the bases targeted for methylation. We propose that DNA binding induces a large rotation of the two HsdM subunits towards the DNA, mediated by hinge bending domains in the specificity subunit HsdS.

L-arginine administration normalizes pressure natriuresis in hypertensive Dahl rats

A blunted pressure-natriuretic response characterizes hypertension in the Dahl salt-sensitive rat. Long-term L-arginine administration prevents hypertension in these animals. To determine if long-term L-arginine corrects the pressure-natriuretic response, we gave salt-sensitive rats on an 8% sodium diet L-arginine or vehicle daily for 3 weeks. Identically treated salt-resistant rats served as controls. After 3 weeks, acute pressure-natriuresis curves were determined. To control for hypertension-induced renal damage, we also examined pressure natriuresis in salt-sensitive rats after short-term L-arginine. Baseline mean arterial pressure was 158 +/- 3 mm Hg in vehicle-treated salt-sensitive rats and 127 +/- 3 mm Hg in chronically L-arginine-treated salt-sensitive rats. During alterations in perfusion pressure, renal blood flow was autoregulated in all groups. Glomerular filtration rate was autoregulated in salt-resistant rats and L-arginine-treated salt-sensitive rats but fell with decreasing pressure in vehicle-treated salt-sensitive rats. Sodium excretion was greater (P < .05) in L-arginine-treated than in vehicle-treated salt-sensitive rats and did not differ from salt-resistant rats at 100, 125, and 158 mm Hg. The slope of the pressure-natriuresis relation was greater (P < .05) in chronically L-arginine-treated than in vehicle-treated salt-sensitive rats. L-Arginine had no effect on natriuresis in salt-resistant rats. Thus, long-term L-arginine administration normalizes pressure-natriuretic responses in salt-sensitive rats. The effect is not due to the prevention of renal damage and is specific to the salt-sensitive strain.(ABSTRACT TRUNCATED AT 250 WORDS)

Substrate recognition and selectivity in the type IC DNA modification methylase M.EcoR124I

The type I DNA modification methylase M.EcoR124I binds sequence specifically to DNA and protects a 25bp fragment containing its cognate recognition sequence from digestion by exonuclease III. Using modified synthetic oligonucleotide duplexes we have investigated the catalytic properties of the methylase, and have established that a specific adenine on each strand of DNA is the site of methylation. We show that the rate of methylation of each adenine is increased at least 100 fold by prior methylation at the other site. However, this is accompanied by a significant decrease in the affinity of the methylase for these substrates according to competitive gel retardation assays. In contrast, methylation of an adenine in the recognition site which is not a target for the enzyme results in only a small decrease in both DNA binding affinity and rate of methylation by the enzyme.

Community-based prevalence profile of arboviral, rickettsial, and Hantaan-like viral antibody in the Nile River Delta of Egypt

To determine the current prevalence of antibody to arboviruses, rickettsiae, and hantaan-like viruses, a survey was carried out in the Nile River Valley of Egypt, one of the principal foci of the 1977-1978 Rift Valley fever (RVF) outbreak. Blood specimens were obtained from 915 persons representing 190 study households. Enzyme immunoassay testing showed that the overall prevalence of IgG antibody was 4% to sand fly fever Sicilian (SFS), 2% to sandfly fever Naples (SFN), 15% to RVF, 20% to West Nile, and 4% to Hantaan (HTN) viruses. Antibody was demonstrated among 32% of the same study subjects to Coxiella burnetii, 58% to Rickettsia typhi, and 32% to R. conorii. The prevalence of agent-specific antibody tended to increase with age. Particularly notable was the low prevalence of RVF infection in children born after the height of the RVF outbreak. No detectable antibodies were found in the population less than seven years of age and in only 3% of those 7-12 years old. In contrast, 26% of the study population 13-19 years old, who were young children and infants at the time of the outbreak, were found to have RVF antibodies, suggesting that the level of intensity associated with transmission decreased considerably following the documented 1977-1978 outbreak. Geometric mean titers (GMT) ranged from 139 for C. burnetii to 1,305 for RVF, and did not vary significantly by age, except for high titers for RVF in the 20-49-year-old age group. A significant upward trend in GMT was also noted when antibody was detected in the specimen for more than one phlebovirus.(ABSTRACT TRUNCATED AT 250 WORDS)

Trends of human immunodeficiency virus type-1 infection in female prostitutes and males diagnosed with a sexually transmitted disease in Djibouti, east Africa

A cross-sectional serosurvey for human immunodeficiency virus type 1 (HIV-1) was conducted during the first quarter of 1991 among high risk groups in Djibouti, East Africa, and compared with previous surveys in 1987, 1988, and 1990. The survey demonstrated evidence of HIV-1 infection in 36.0% (n = 292) of street prostitutes, 15.3% (n = 360) of prostitutes working as bar hostesses, and 10.4% (n = 193) of males diagnosed with a sexually transmitted disease. By multivariate modeling, HIV-1 seropositivity in prostitutes was associated with Ethiopian nationality, working as a street prostitute, and residing in Djibouti for two years or less. We suggest that prostitution, particularly street prostitution, is a major route of HIV-1 transmission in Djibouti.