Benchmarking highly entangled states on a 60-atom analogue quantum simulator

Quantum systems have entered a competitive regime in which classical computers must make approximations to represent highly entangled quantum states1,2. However, in this beyond-classically-exact regime, fidelity comparisons between quantum and classical systems have so far been limited to digital quantum devices2-5, and it remains unsolved how to estimate the actual entanglement content of experiments6. Here, we perform fidelity benchmarking and mixed-state entanglement estimation with a 60-atom analogue Rydberg quantum simulator, reaching a high-entanglement entropy regime in which exact classical simulation becomes impractical. Our benchmarking protocol involves extrapolation from comparisons against an approximate classical algorithm, introduced here, with varying entanglement limits. We then develop and demonstrate an estimator of the experimental mixed-state entanglement6, finding our experiment is competitive with state-of-the-art digital quantum devices performing random circuit evolution2-5. Finally, we compare the experimental fidelity against that achieved by various approximate classical algorithms, and find that only the algorithm we introduce is able to keep pace with the experiment on the classical hardware we use. Our results enable a new model for evaluating the ability of both analogue and digital quantum devices to generate entanglement in the beyond-classically-exact regime, and highlight the evolving divide between quantum and classical systems.

Erasure conversion in a high-fidelity Rydberg quantum simulator

Minimizing and understanding errors is critical for quantum science, both in noisy intermediate scale quantum (NISQ) devices1 and for the quest towards fault-tolerant quantum computation2,3. Rydberg arrays have emerged as a prominent platform in this context4 with impressive system sizes5,6 and proposals suggesting how error-correction thresholds could be significantly improved by detecting leakage errors with single-atom resolution7,8, a form of erasure error conversion9-12. However, two-qubit entanglement fidelities in Rydberg atom arrays13,14 have lagged behind competitors15,16 and this type of erasure conversion is yet to be realized for matter-based qubits in general. Here we demonstrate both erasure conversion and high-fidelity Bell state generation using a Rydberg quantum simulator5,6,17,18. When excising data with erasure errors observed via fast imaging of alkaline-earth atoms19-22, we achieve a Bell state fidelity of [Formula: see text], which improves to [Formula: see text] when correcting for remaining state-preparation errors. We further apply erasure conversion in a quantum simulation experiment for quasi-adiabatic preparation of long-range order across a quantum phase transition, and reveal the otherwise hidden impact of these errors on the simulation outcome. Our work demonstrates the capability for Rydberg-based entanglement to reach fidelities in the 0.999 regime, with higher fidelities a question of technical improvements, and shows how erasure conversion can be utilized in NISQ devices. These techniques could be translated directly to quantum-error-correction codes with the addition of long-lived qubits7,22-24.

Preparing random states and benchmarking with many-body quantum chaos

Producing quantum states at random has become increasingly important in modern quantum science, with applications being both theoretical and practical. In particular, ensembles of such randomly distributed, but pure, quantum states underlie our understanding of complexity in quantum circuits¹ and black holes², and have been used for benchmarking quantum devices^3,4 in tests of quantum advantage^5,6. However, creating random ensembles has necessitated a high degree of spatio-temporal control^7-12 placing such studies out of reach for a wide class of quantum systems. Here we solve this problem by predicting and experimentally observing the emergence of random state ensembles naturally under time-independent Hamiltonian dynamics, which we use to implement an efficient, widely applicable benchmarking protocol. The observed random ensembles emerge from projective measurements and are intimately linked to universal correlations built up between subsystems of a larger quantum system, offering new insights into quantum thermalization¹³. Predicated on this discovery, we develop a fidelity estimation scheme, which we demonstrate for a Rydberg quantum simulator with up to 25 atoms using fewer than 10⁴ experimental samples. This method has broad applicability, as we demonstrate for Hamiltonian parameter estimation, target-state generation benchmarking, and comparison of analogue and digital quantum devices. Our work has implications for understanding randomness in quantum dynamics¹⁴ and enables applications of this concept in a much wider context^{4,5,9,10,15-20}.

Pulsed-pump phosphorus-doped fiber Raman amplifier around 1260 nm for applications in quantum non-linear optics

We describe a fiber Raman amplifier for nanosecond and sub-nanosecond pulses centered around 1260 nm. The amplification takes place inside a 4.5-m-long polarization-maintaining phosphorus-doped fiber, pumped at 1080 nm by 3-ns-long pulses with a repetition rate of 200 kHz and up to 1.75 kW peak power. The input seed pulses are of sub-mW peak-power and minimal duration of 0.25 ns, carved out of a continuous-wave laser with sub-MHz linewidth. We obtain linearly polarized output pulses with peak powers of up to 1.4 kW, corresponding to peak-power conversion efficiency of over 80%. An ultrahigh small signal gain of 90 dB is achieved, and the signal-to-noise ratio 3 dB below the saturation power is above 20 dB. No significant temporal and spectral broadening is observed for output pulses up to 400 W peak power, and broadening at higher powers can be reduced by phase modulation of the seed pulse. Thus, nearly-transform-limited pulses with peak power up to 1 kW are obtained. Finally, we demonstrate the generation of pulses with controllable frequency chirp, pulses with variable width, and double pulses. This amplifier is thus suitable for coherent control of narrow atomic resonances, especially for the fast and coherent excitation of rubidium atoms to Rydberg states. These abilities open the way towards several important applications in quantum non-linear optics.

Recovering the Homogeneous Absorption of Inhomogeneous Media

The resonant absorption of light by an ensemble of absorbers decreases when the resonance is inhomogeneously broadened. Recovering the lost absorption cross section is of great importance for various applications of light-matter interactions, particularly in quantum optics, but no recovery mechanism has yet been identified and successfully demonstrated. Here, we formulate the limit set by the inhomogeneity on the absorption, and present a mechanism able to circumvent this limit and fully recover the homogeneous absorption of the ensemble. We experimentally study this mechanism using two different level schemes in atomic vapors and demonstrate up to fivefold enhancement of the absorption above the inhomogeneous limit. Our scheme relies on light shifts induced by auxiliary fields and is thus applicable to various physical systems and inhomogeneity mechanisms.

Fast, noise-free memory for photon synchronization at room temperature

Future quantum photonic networks require coherent optical memories for synchronizing quantum sources and gates of probabilistic nature. We demonstrate a fast ladder memory (FLAME) mapping the optical field onto the superposition between electronic orbitals of rubidium vapor. Using a ladder-level system of orbital transitions with nearly degenerate frequencies simultaneously enables high bandwidth, low noise, and long memory lifetime. We store and retrieve 1.7-ns-long pulses, containing 0.5 photons on average, and observe short-time external efficiency of 25%, memory lifetime (1/e) of 86 ns, and below 10-4 added noise photons. Consequently, coupling this memory to a probabilistic source would enhance the on-demand photon generation probability by a factor of 12, the highest number yet reported for a noise-free, room temperature memory. This paves the way toward the controlled production of large quantum states of light from probabilistic photon sources.

Correction to: Reducing surgical site infections following total hip and knee arthroplasty: an Israeli experience

In the original article, one of the co-author's family name has been published incorrectly.

Reducing surgical site infections following total hip and knee arthroplasty: an Israeli experience

PURPOSE

To assess the changes observed in surgical site infection (SSI) rates following total joint arthroplasty (TJA) after the introduction of an infection control programme and evaluate the risk factors for the development of these infections.

DESIGN

Prospective cohort study.

SETTING

Large tertiary medical centre in Israel.

METHODS

Data about SSIs and potential prophylaxis-, patient-, and procedure-related risk factors were collected for all patients who underwent elective total hip and total knee arthroplasty during the study period. Multivariant analyses were conducted to determine which significant covariates affected the outcome.

RESULTS

During the 76-month study period, SSIs (superficial and deep) occurred in 64 (4.4%) of 1554 patients. As compared with the 34 (7.7%) SSIs that occurred in the first 25 months, there were 23 (4.7%) SSIs in the following 25 months, and only 7 (1.3%) SSIs in the last third of the study (p = 0.058 and <0.001, respectively). A multiple logistic regression model indicated that risk factors for prosthetic joint infection were a National Nosocomial Infections Surveillance (NNIS) System surgical patient risk index score of 1 (OR 1.8; 95% CI 1.1-3.1) or 2 (OR 2.8; 95% CI 1.2-11.8). The incidence of SSI was not correlated with the timing, nor the duration of antibiotic prophylaxis.

CONCLUSIONS

The introduction of preventive measures and surveillance coincided with a significant reduction in SSIs following TJA in our institution. The risk of infection correlated with higher scores in the NNIS System surgical patient risk.

Two orthodenticle-related genes in the short-germ beetle Tribolium castaneum

To investigate the molecular basis of head evolution, we searched for genes related to the Drosophila orthodenticle (otd) homeobox gene in the short-germ beetle Tribolium castaneum. Unexpectedly, we found that there are two otd-related genes in Tribolium, with predicted homeodomains highly similar to that of the single Drosophila gene. One of the two genes (Tc otd-1) is more related in both amino acid sequence and expression pattern to fruitfly otd. Tc otd-1 is expressed in a broad anterior stripe in the blastoderm embryo, suggesting a role in early head segmentation similar to that of the Drosophila gene. The second gene (Tc otd-2) is more similar in sequence to the otd-related genes isolated from different vertebrate species (the Otx gene family). Tc otd-2 is not transcribed in the blastoderm, but is expressed later in more limited subsets of cells in the anterior brain. Both Tribolium genes and the Drosophila gene are, unlike the vertebrate genes, also expressed at the developing ventral midline of the embryo. Our results are consistent with the idea that an otd/Otx gene specified anterior head structures in the last ancestor common to arthropods and vertebrates. Within the arthropod lineage, we propose that this gene acquired a function in cells at the developing midline prior to the duplication that generated the two Tribolium genes.

Impact of carbapenem resistance on the outcome of patients' hospital-acquired bacteraemia caused by Klebsiella pneumoniae

BACKGROUND

Carbapenem-resistant Enterobacteriaceae, especially Klebsiella spp., have become a major health problem recently worldwide. Since 2006 the incidence of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections has increased substantially in Israel. Bloodstream infections (BSIs) caused by these strains have been associated with high rates of treatment failure and mortality.

AIM

This study was designed to identify risk factors for carbapenem resistance among patients with healthcare-related (HCR) K. pneumoniae bacteraemia and predictors of mortality associated with HCR-CRKP bacteraemia compared with carbapenem-susceptible K. pneumoniae (CSKP).

METHODS

In this retrospective case-control study, all cases of K. pneumoniae bacteraemia during 2006-2008 were identified. Resistance patterns, underlying morbidities, risk factors for drug resistance and mortality rates were compared for patients with CRKP and CSKP bacteraemia.

FINDINGS

Two hundred and fourteen patients with CSKP bacteraemia were compared with 103 patients with CRKP bacteraemia. Severe, chronic comorbidities and prior antibiotic use were more frequent among patients with CRKP bacteraemia. On multivariate analysis prior use of macrolides and antibiotic exposure for ≥14 days remained the only independent factors associated with CRKP bacteraemia. Mortality rates of CRKP patients were significantly higher than those of CSKP patients. On multivariate analyses: bedridden status, chronic liver disease, Charlson comorbidity index ≥5, mechanical ventilation, and haemodialysis remained independently associated with mortality among patients with K. pneumoniae bacteraemia. Carbapenem resistance was not a risk factor for mortality.

CONCLUSIONS

Previous antibiotic exposure is a risk factor for CRKP-BSI. Mortality among patients with K. pneumoniae bacteraemia is associated with serious comorbidities, but not with carbapenem resistance.

The CASE adherence index: A novel method for measuring adherence to antiretroviral therapy

The Center for Adherence Support Evaluation (CASE) Adherence Index, a simple composite measure of self-reported antiretroviral therapy (ART) adherence, was compared to a standard three-day self-reported adherence measure among participants in a longitudinal, prospective cross-site evaluation of 12 adherence programs throughout the United States. The CASE Adherence Index, consisting of three unique adherence questions developed for the cross-site study, along with a three-day adherence self-report were administered by interviews every three months over a one-year period. Data from the three cross-site adherence questions (individually and in combination) were compared to three -day self-report data and HIV RNA and CD4 outcomes in cross-sectional analyses. The CASE Adherence Index correlated strongly with the three-day self-reported adherence data (p < 0.001) and was more strongly associated with HIV outcomes, including a 1-log decline in HIV RNA level (maximum OR = 2.34; p < 0.05), HIV RNA < 400 copies/ml (maximum OR = 2.33; p < 0.05) and performed as well as the three-day self-report when predicting CD4 count status. Participants with a CASE Index score >10 achieved a 98 cell mean increase in CD4 count over 12 months, compared to a 41 cell increase for those with scores < or =10 (p < 0.05). The CASE Adherence Index is an easy to administer instrument that provides an alternative method for assessing ART adherence in clinical settings.

The cost of HIV medication adherence support interventions: Results of a cross-site evaluation

The objective of this study was to determine the direct cost of HIV adherence support programmes participating in a cross-site evaluation in the US. Data on the frequency, type, and setting of adherence encounters; providers' professions; and adherence tools provided were collected for 1,122 patients enrolled in 13 interventions at 9 sites. The site staff estimated the average duration of each type of encounter and national wage rates were used for labour costs. The median (range) adherence encounters/year among interventions was 16.5 (4.3-104.6) per patient; encounters lasted 24.6 (8.9-40.9) minutes. Intervention direct cost was correlated with the average frequency of encounters (r = 0.57), but not with encounter duration or providers' professions. The median direct cost/month was 35 dollars(5 dollars-58 dollars) per patient, and included direct provider costs (66%); incentives (17%); reminders and other tools (8%); and direct administrative time, provider transportation, training, and home delivery (9%). The median direct cost/month from a societal perspective, which includes patient time and travel costs, was 47 dollars(24 dollars-114 dollars) per patient. Adherence interventions with moderate efficacy costing < or =100 dollars/month have been estimated to meet a cost-effectiveness threshold that is generally accepted in the US. Payers should consider enhanced reimbursement for adherence support services.

Severe hypoxemia in a patient with acute myocardial infarction

A case report of a patient with acute myocardial infarction and severe hypoxemia due to acute right to left interatrial shunt (RLIAS) is presented. Diagnostic and therapeutic procedures are discussed.

An outbreak of Q fever in an urban area in Israel

Reported here is an outbreak of 21 cases of Q fever that were diagnosed during 5 months in the spring and summer of 2001 at Rambam Medical Center, Haifa, Israel. An epidemiological investigation and a case-control study were conducted to identify risk factors associated with acquisition of the disease in this outbreak. Patients were more likely than controls to live in Krayot (a large suburb of Haifa) (76.2% vs. 41.5%; p=0.005), to have more contact with animals (usually pets) (66.7% vs. 26.9%; p=0.007), and to consume more unpasteurized dairy products (23.8% vs. 0%; p=0.01). The Krayot suburb is an entirely urban area, but several livestock facilities are located in its close vicinity, and some of them have been reported to harbor Q fever. Although the patients did not recall having had direct contact with farm animals, the results suggest the presence of livestock facilities in such close proximity to a residential area may cause urban outbreaks of Q fever.

HIV-related knowledge and adherence to HAART

Near perfect adherence is considered essential for patients on HAART, yet adherence to medical recommendations is rarely so high. Supportive services and reminder tools may help individuals to become adherent, yet it is difficult to determine who may need such interventions. In this study, based on data from the NYSDOH/AIDS Institute Treatment Adherence Demonstration Program, we look at the association between HIV-related knowledge and adherence, hypothesizing that a better understanding of HIV and its treatment is associated with better adherence. In analyses based on 997 participants, knowledge, as measured by five true/false questions, was significantly associated with self-reported adherence. In multivariate analysis, compared to persons with four or five items answered correctly, persons with fewer correct answers were more likely to report missed doses (OR = 1.72 for 2-3 correct, p < 0.01; OR = 2.92 for 0-1 correct, p < 0.05). Our data suggest that providers should include questions focused on knowledge of HIV in their assessments of medication readiness and need for adherence support. Similarly, providers should be diligent with respect to patient education, ensuring that each patient has the information needed to support reasoned decision making and adequate adherence.

Nosocomial outbreak of Legionella pneumophila serogroup 3 pneumonia in a new bone marrow transplant unit: evaluation, treatment and control

A nosocomial outbreak of pneumonia caused by Legionella pneumophila serogroup 3 occurred in four patients following hematopoietic stem cell transplantation (HSCT) in a new bone marrow transplantation (BMT) unit during a 2 week period. The causative organism was recovered from the water supply system to the same unit just before the outbreak. Nineteen other BMT patients were hospitalized in the same unit at the same time, giving a frequency of proven infection of 4/23 = 17%. Immediately after recognition of the outbreak, use of tap water was forbidden, humidifiers were disconnected, and ciprofloxacin prophylaxis was started for all patients in the unit, until decontamination of the water was achieved. No other cases were detected. In conclusion, contamination of the hospital water supply system with legionella carries a high risk for legionella pneumonia among BMT patients. Early recognition of the outbreak, immediate restrictions of water use, antibiotic prophylaxis for all non-infected patients, and water decontamination, successfully terminated the outbreak.

Clinical and epidemiologic significance of coagulase-negative staphylococci bacteremia in a tertiary care university Israeli hospital

OBJECTIVES

To characterize the clinical significance of coagulase-negative staphylococci (CNS) bacteremia.

DESIGN

Prospective cohort study.

SETTING

A 900-bed hospital in Haifa, Israel, from November 1996 to March 1997.

RESULTS

Of 137 episodes of positive blood cultures for CNS, 41 (30%) were considered as true infection. Twenty-seven of 119 episodes associated with only 1 blood culture positive for CNS (23%) met the definition of infection as compared with 14 of 18 episodes (78%) associated with 2 or more blood cultures positive for CNS (P <.001). Methicillin resistance was significantly more frequent among Staphylococcus epidermidis isolates of episodes of true bacteremia than of episodes of contamination (15 of 22 [68%] vs. 11 of 33 [33%], respectively; P =.02). S hominis was isolated only in episodes considered as contamination (P =.01). It was estimated that CNS represents 24% of all nosocomial bloodstream pathogens. When CNS were isolated in the first 48 hours of hospitalization, an intravascular device was more frequently associated with episodes of true bacteremia than in those considered as contamination (7 of 7 [100%] vs. 10 of 57 [18%], respectively; P <.001). The mortality rate among patients with true CNS bacteremia was 16%.

CONCLUSION

Some laboratory parameters may help identify episodes of true CNS bacteremia, which appears to be more common than previously considered.

Vancomycin versus cefazolin prophylaxis for cardiac surgery in the setting of a high prevalence of methicillin-resistant staphylococcal infections

OBJECTIVE

This study was undertaken to compare the efficacy of vancomycin prophylaxis with that of cefazolin in preventing surgical site infections in a tertiary medical center with a high prevalence of methicillin-resistant staphylococcal infections.

METHODS

All adult patients (> or = 18 years) scheduled for cardiac surgery requiring sternotomy were randomly assigned to receive vancomycin (1 g every 12 hours) or cefazolin (1 g every 8 hours). Prophylaxis was started during the induction of anesthesia and continued for only 24 hours. Patients were followed up for at least 30 days (1 year for those receiving a cardiac implant). Surgical site infections were stratified according to the National Nosocomial Infections Surveillance System risk index.

RESULTS

Of the 885 patients included in the study, 452 received vancomycin and 433 received cefazolin. The overall surgical site infection rates were similar in the two groups (43 cases in the vancomycin group, 9.5%, vs 39 cases in the cefazolin group, 9.0%, P =.8). Superficial and deep incisional surgical site infection rates were also similar in the two groups. There was a trend toward more frequent organ-space infections and infections with beta-lactam-resistant organisms among patients receiving cefazolin, but this trend did not reach statistical significance. In contrast, surgical site infections caused by methicillin-susceptible staphylococci were significantly more common in the vancomycin group (17 cases, 3.7%, vs 6 cases, 1.3%, P =.04). The durations of postoperative hospitalization and the mortalities were similar in the two groups.

CONCLUSIONS

This trial suggests that vancomycin and cefazolin have similar efficacy in preventing surgical site infections in cardiac surgery.

Establishing priorities in neurofibromatosis research: a workshop summary

Progress in understanding the biology of the neurofibromatoses (NF1 and NF2) offers hope for the development of new, effective methods of treatment. In May 2000, the National Institute of Neurological Disorders and Stroke (NINDS) hosted a workshop that included leading researchers and clinicians from the NF community. The goal of the meeting was to assess current knowledge and identify priorities for future research. Needs identified included the development of better animal models, further study of the function of the NF1 and NF2 genes, and investigation of the role of modifier genes. The participants agreed that it will also be important to define further the natural history of NF1 and NF2 and to develop an infrastructure to support clinical trials. They also discussed the possible creation of research consortia and NF centers to promote the integration of basic and clinical research.

Invasive pulmonary aspergillosis in neutropenic patients during hospital construction: before and after chemoprophylaxis and institution of HEPA filters

Between September 1993 and December 1993, during extensive hospital construction and indoor renovation, a nosocomial outbreak of invasive pulmonary aspergillosis occurred in acute leukemia patients treated in a regular ward that has only natural ventilation. The observed infection rate was 50%. Chemoprophylaxis with intravenous continuous low-dose amphotericin B was then instituted as a preventive measure. During the next 18 months invasive pulmonary aspergillosis developed in 43% of acute leukemia patients. After that period a new hematology ward was opened with an air filtration system through high-efficiency particulate air filtration (HEPA) filters, and a bone marrow transplantation program was started on the hematology service. During the following three years, none of the acute leukemia or bone marrow transplantation patients who were hospitalized exclusively in the hematology ward developed invasive pulmonary aspergillosis, although 29% of acute leukemia patients who were housed in a regular ward, because of shortage of space in the new facility, still contracted invasive pulmonary aspergillosis. Overall, 31 patients were diagnosed with invasive pulmonary aspergillosis during almost five years: 74% of patients recovered from invasive pulmonary aspergillosis, and 42% are long-term survivors; 26% of patients died of resistant leukemia with aspergillosis, but no one died of invasive pulmonary aspergillosis alone. In conclusion, during an on-going construction period, an extremely high incidence rate of invasive pulmonary aspergillosis in acute leukemia patients undergoing intensive chemotherapy was observed. Institution of low-dose intravenous amphotericin B prophylaxis marginally reduced the incidence rate of invasive pulmonary aspergillosis. Keeping patients in a special ward with air filtration through a HEPA system eliminated invasive pulmonary aspergillosis completely. Among patients who developed invasive pulmonary aspergillosis, early diagnosis and treatment are probably the explanation for the favorable outcome.

Epidermal growth factor receptor signaling activates orthodenticle expression during Drosophila head development

The relation between signal transduction pathways and the genes that specify regional identity remains poorly understood. We investigated the interaction between the epidermal growth factor receptor (EGFR) pathway and the homeobox gene orthodenticle (otd), which specifies cell fate during head development. Previous studies of head formation in Drosophila melanogaster demonstrated that reducing either EGFR signaling or otd expression in the imaginal primordium of the dorsal head capsule eliminates the ocelli and other dorsal head structures. Here, we show that blocking EGFR signaling reduces otd expression and that activating EGFR signaling outside this primordium induces ectopic otd expression. We also demonstrate that loss of EGFR can be rescued by constitutive otd expression. Our results indicate that otd is a downstream target of the EGFR pathway during head development.

A homologue of the calcium-binding disulfide isomerase CaBP1 is expressed in the developing CNS of Drosophila melanogaster

Previous studies identified a group of proteins localized to the endoplasmic reticulum (ER) that bind calcium and direct protein folding. Three of these proteins, CaBP1, CaBP2, and protein disulfide isomerase, have been purified from rat microsomes and analyzed biochemically. However, their function in vivo has not been determined. Here, we report the isolation of a homologue of the CaBP1 gene from the fruitfly Drosophila melanogaster (DmCaBP1). The predicted sequence of the Drosophila protein is very similar to that of rat CaBP1 and retains motifs thought to be functionally important in the mammalian protein. We show that DmCaBP1 is expressed in a specific spatiotemporal pattern during embryogenesis. In particular, it is expressed in midline precursor cells in the developing CNS. This is the first demonstration of tissue-specific expression for a member of this group of ER proteins and suggests a possible role for DmCABP1 as a molecular chaperone involved in nervous system development. The identification of the DmCaBP1 gene provides a basis for future genetic studies of its function.

Device-associated, device-day infection rates in an Israeli adult general intensive care unit

Surveillance is an essential element of hospital infection control programs. Previous studies have shown that interhospital comparison of intensive care unit (ICU) nosocomial infections (NI) may be best made by comparing ICU-type-specific, device-associated infection rates and that these adjusted rates vary by ICU type. The aim of this study was to evaluate whether significant structural improvements introduced in an adult general ICU were associated with changes in the NI rates in this unit. In addition, we compared these rates with those of ICUs reported by the National Nosocomial Infections Surveillance (NNIS) System of the Centers for Diseases Control and Prevention. During a 12-month period 337 patients were surveyed. There were 20 ventilator-associated pneumonias (VAP)/1000 ventilator (VEN)-days, 12 bloodstream infections (BSI)/1000 central vascular catheter (CVC)-days and 14 urinary tract infection (UTI)/1000 indwelling urinary catheter (IUC)-days. Structural changes and reduction in device utilization ratios were not followed by change in NI rates in this unit. VAP and BSI rates were comparable to those reported for neurosurgical and burn ICUs, respectively, in the NNIS System, despite a much higher device utilization ratios. The present study provides specific surveillance data for further interhospital comparison with similar types of ICUs.

Epidemiology of candidemia--a nationwide survey in Israel

Bloodstream infections with Candida are often lethal and have been reported to be increasing in frequency. The current retrospective study describes the magnitude and epidemiological characteristics of candidemia in all western-type hospital facilities in Israel in 1994. Comprehensiveness of the data from the reporting hospitals was checked by cross-study of the data from the infectious diseases records and from the hospitalization records. Vital status of all reported cases was evaluated 1 year after the diagnosis. Data on 298 newly diagnosed cases of candidemia were received from 14 of the 18 general hospitals in Israel. The proportion of candidemia in the Israeli hospitals ranged from 0.1 to 0.01% of all admissions, with a mean of 0.05%. The incidence of candidemia differed significantly between the wards from 4-5/10,000 in general surgery and internal medicine wards to about 60/10,000 and 80/10,000 in intensive care and preterm units, respectively. Of all detected cases 53.6% were Candida albicans. Another nine specific species of Candida (mainly Candida parapsilosis, Candida tropicalis and Candida glabrata) were detected, with major differences between the various hospitals. The species of Candida differed significantly by sex and age. Of the cases of candidemia 21.5% died within 30 days of the isolation of the pathogen. The one-year mortality rate was 31.9%. Species-specific 30-day mortality rate was highest for C. glabrata. Throughout the analysis, C. glabrata emerged as a unique cause of candidemia, producing higher mortality, appearing at a younger age and predominating among females.

Evaluating supervised HAART in late-stage HIV among drug users: a preliminary report

OBJECTIVE

To examine response to highly active antiretroviral therapy (HAART) among a sample of treatment-experienced patients in the late stage of human immunodeficiency virus (HIV) infection in residential health care facilities (RHCFs) in New York City facilities designated for HIV/AIDS (acquired immunodeficiency syndrome) when access and adherence are maximized.

METHODS

Medical record review of 111 patients.

RESULTS

Demographics were mean age 42 years; 58% male; 60% African-American; 31% Hispanic; 57% injection drug users (IDUs); 23% with history of dementia; 52% hepatitis C virus (HCV) antibody seropositive; 80% on HAART, of whom 18% had lipodystrophy. Of 88 patients on HAART, 52% had a decreased viral load (>1/2 log) versus 13% of 23 not on HAART (P<.05); a >1/2 log viral load increase was seen in 8% and 35%, respectively (P<.05). Those with viral load increase were more likely than those with stable/decreased viral load to be IDUs (71% vs. 64%) and to have HCV seropositivity (86% vs. 53%), even with similar initial CD4+ cell count, viral load, and follow-up time.

CONCLUSION

In a predominantly minority IDU population who are treatment experienced, 50% of the patients successfully responded to treatment with supervised therapy. The RHCFs in New York City provide a unique opportunity to examine further factors associated with response to HAART in an environment in which medication administration and adherence are maximized and monitored carefully.

Clinical, epidemiological, and microbiological features of Vibrio vulnificus biogroup 3 causing outbreaks of wound infection and bacteraemia in Israel. Israel Vibrio Study Group

BACKGROUND

Vibrio vulnificus is a gram-negative bacterium that causes septicaemia and wound infection. Cases occur sporadically, and no previous outbreaks due to a common source or a clonal strain have been reported. In the summer and autumn of 1996 and 1997, an outbreak of invasive V. vulnificus infection occurred in Israel in people who had recently handled fresh, whole fish purchased from artificial fish-ponds.

METHODS

We reviewed clinical and epidemiological information, and undertook an environmental investigation to assess disease characteristics, modes of transmission, phenotypic characteristics of the bacterium, and fish-marketing policy. The clonal nature of 19 isolates was studied by biotyping, pulsed-field gel electrophoresis, and restriction-fragment length polymorphism (RFLP) analysis of a PCR fragment.

FINDINGS

During 1996-97, 62 cases of wound infection and bacteraemia occurred. 57 patients developed cellulitis, four had necrotising fasciitis, and one developed osteomyelitis. In all cases, the fish were cultivated in inland fish-ponds. In the summer of 1996, fish-pond managers initiated a new marketing policy, in which fish were sold alive instead of being packed in ice. Phenotypically, the isolates had five atypical biochemical test results. The isolates were non-typeable by pulsed-field gel electrophoresis, and all had the same PCR-RFLP pattern which had not been seen previously.

INTERPRETATION

The cause of the outbreak was a new strain of V. vulnificus, classified as biogroup 3. A new fish-marketing policy that began in 1996 may have exposed susceptible people to the organism.

Identification of a Drosophila prolyl endopeptidase and analysis of its expression

Prolyl endopeptidases (PEPs) are believed to be involved in the metabolism of neuropeptide hormones (reviewed in Mentlein [1988]). Genes encoding PEPs have been isolated from various species, but their expression patterns during development have not been determined. In this study, we isolated a gene encoding a predicted PEP from the fruitfly Drosophila melanogaster. The gene encodes a predicted 756-amino acid protein having extensive sequence similarity to human PEP. We demonstrated that the Drosophila gene (DPEP) is expressed in a spatially restricted pattern in imaginal discs and the larval brain. Our results suggest a role for DPEP in the regional specification of larval tissues. They also provide a starting point for a genetic analysis of the function of this enzyme during development.

Hedgehog activates the EGF receptor pathway during Drosophila head development

The Hedgehog (Hh) and Epidermal growth factor receptor (EGFR) signaling pathways play critical roles in pattern formation and cell proliferation in invertebrates and vertebrates. In this study, we demonstrate a direct link between these two pathways in Drosophila melanogaster. Hh and EGFR signaling are each required for the formation of a specific region of the head of the adult fruitfly. We show that hh and vein (vn), which encodes a ligand of the Drosophila EGFR (Schnepp, B., Grumbling, G., Donaldson, T. and Simcox, A. (1996) Genes Dev. 10, 2302–13), are expressed in adjacent domains within the imaginal primordium of this region. Using loss- and gain-of-function approaches, we demonstrate that Hh activates vn expression. We also show that Hh activation of vn is mediated through the gene cubitus interruptus (ci) and that this activation requires the C-terminal region of the Ci protein. Finally, we demonstrate that wingless (wg) represses vn expression, thereby limiting the domain of EGFR signaling.

[Empirical treatment of urinary tract infections in the delivery room--findings and desires]

Urinary tract infection (UTI) is the most common bacterial infection during pregnancy. In prenatal and delivery wards treatment is usually started at once in pregnant women with symptoms suggesting UTI, but there is no uniformity as to treatment. We surveyed such treatment in the delivery rooms throughout Israel, and whether the treatment differed in simple cystitis as opposed to pyelonephritis. Results of positive urine cultures from symptomatic parturients admitted here during 1995-1996 were examined. There were 17 different empiric treatment protocols in 28 delivery rooms, whose daily cost ranged from 1-119 NIS. We present the antimicrobial sensitivity of 156 bacteria isolated from the urinary cultures from pregnant women in our prenatal ward. Based upon urinary flora, sensitivity and daily cost, we suggest a protocol for empiric treatment. We recommend first and second generation cephalosporins for treatment of simple lower (UTIs), while gentamicin is suggested for treatment of clinical pyelonephritis during pregnancy. There is no medical nor economic justification for the multiplicity of empiric treatment protocols currently used. Considering our results, our protocol is cost-effective for the empiric treatment of UTI in hospitalized parturients and in the community as well.

Targeting gene expression to the head: the Drosophila orthodenticle gene is a direct target of the Bicoid morphogen

The Bicoid (Bcd) morphogen establishes the head and thorax of the Drosophila embryo. Bcd activates the transcription of identified target genes in the thoracic segments, but its mechanism of action in the head remains poorly understood. It has been proposed that Bcd directly activates the cephalic gap genes, which are the first zygotic genes to be expressed in the head primordium. It has also been suggested that the affinity of Bcd-binding sites in the promoters of Bcd target genes determines the posterior extent of their expression (the Gene X model). However, both these hypotheses remain untested. Here, we show that a small regulatory region upstream of the cephalic gap gene orthodenticle (otd) is sufficient to recapitulate early otd expression in the head primordium. This region contains two control elements, each capable of driving otd-like expression. The first element has consensus Bcd target sites that bind Bcd in vitro and are necessary for head-specific expression. As predicted by the Gene X model, this element has a relatively low affinity for Bcd. Surprisingly, the second regulatory element has no Bcd sites. Instead, it contains a repeated sequence motif similar to a regulatory element found in the promoters of otd-related genes in vertebrates. Our study is the first demonstration that a cephalic gap gene is directly regulated by Bcd. However, it also shows that zygotic gene expression can be targeted to the head primordium without direct Bcd regulation.

Ectopic orthodenticle expression alters segment polarity gene expression but not head segment identity in the Drosophila embryo

The cephalic gap genes specify anterior head development in the Drosophila embryo. However, the mechanisms of action of these genes remain poorly understood. Here, we focused on the cephalic gap gene orthodenticle (otd), which establishes a specific region of the anterior head. It has been proposed that otd acts in a combinatorial fashion with the cephalic gap genes empty spiracles (ems) and buttonhead (btd) to assign segmental identities in this region. To test this model, we used a heat-inducible transgene to generate pulses of ubiquitous otd expression during embryonic development. Ectopic otd expression caused significant defects in head formation, including the duplication of sensory structures derived from otd-dependent segments. However, these defects do not appear to result from the transformation of head segment identities predicted by the combinatorial model. Instead, they correlate with specific regulatory effects of otd on the expression of the segment polarity genes engrailed (en) and wingless (wg). Ectopic otd expression also caused the loss of head structures derived from the maxillary segment, which lies posterior to the otd domain. We show that this effect is associated with otd repression of the homeotic selector gene Deformed (Dfd).

Murine Otx1 and Drosophila otd genes share conserved genetic functions required in invertebrate and vertebrate brain development

Despite the obvious differences in anatomy between invertebrate and vertebrate brains, several genes involved in the development of both brain types belong to the same family and share similarities in expression patterns. Drosophila orthodenticle (otd) and murine Otx genes exemplify this, both in terms of expression patterns and mutant phenotypes. In contrast, sequence comparison of OTD and OTX gene products indicates that homology is restricted to the homeodomain suggesting that protein divergence outside the homeodomain might account for functional differences acquired during brain evolution. In order to gain insight into this possibility, we replaced the murine Otx1 gene with a Drosophila otd cDNA. Strikingly, epilepsy and corticogenesis defects due to the absence of Otx1 were fully rescued in homozygous otd mice. A partial rescue was also observed for the impairments of mesencephalon, eye and lachrymal gland. In contrast, defects of the inner ear were not improved suggesting a vertebrate Otx1-specific function involved in morphogenesis of this structure. Furthermore, otd, like Otx1, was able to cooperate genetically with Otx2 in brain patterning, although with reduced efficiency. These data favour an extended functional conservation between Drosophila otd and murine Otx1 genes and support the idea that conserved genetic functions required in mammalian brain development evolved in a primitive ancestor of both flies and mice.

Equivalence of the fly orthodenticle gene and the human OTX genes in embryonic brain development of Drosophila

Members of the orthodenticle gene family are essential for embryonic brain development in animals as diverse as insects and mammals. In Drosophila, mutational inactivation of the orthodenticle gene results in deletions in anterior parts of the embryonic brain and in defects in the ventral nerve cord. In the mouse, targeted elimination of the homologous Otx2 or Otx1 genes causes defects in forebrain and/or midbrain development. To determine the morphogenetic properties and the extent of evolutionary conservation of the orthodenticle gene family in embryonic brain development, genetic rescue experiments were carried out in Drosophila. Ubiquitous overexpression of the orthodenticle gene rescues both the brain defects and the ventral nerve cord defects in orthodenticle mutant embryos; morphology and nervous system-specific gene expression are restored. Two different time windows exist for the rescue of the brain versus the ventral nerve cord. Ubiquitous overexpression of the human OTX1 or OTX2 genes also rescues the brain and ventral nerve cord phenotypes in orthodenticle mutant embryos; in the brain, the efficiency of morphological rescue is lower than that obtained with overexpression of orthodenticle. Overexpression of either orthodenticle or the human OTX gene homologs in the wild-type embryo results in ectopic neural structures. The rescue of highly complex brain structures in Drosophila by either fly or human orthodenticle gene homologs indicates that these genes are interchangeable between vertebrates and invertebrates and provides further evidence for an evolutionarily conserved role of the orthodenticle gene family in brain development.

Developmental rescue of Drosophila cephalic defects by the human Otx genes

The molecular mechanisms of head development are a central question in vertebrate and invertebrate developmental biology. The anteriorly expressed homeobox gene otd in Drosophila and its homolog Otx in mouse are required for the early development of the most anterior part of the body, suggesting that a fundamental genetic program of cephalic development might be conserved between vertebrates and invertebrates. We have examined this hypothesis by introducing the human Otx genes into flies. By inducing expression of the human Otx homologs with a heat shock promoter, we found that both Otx1 and Otx2 functionally complement the cephalic defects of a fly otd mutant through specific activation and inactivation of downstream genes. Combined with previous morphological studies, these results are consistent with the view that a common molecular ground plan of cephalization was invented before the diversification of the protostome and the deuterostome in the course of metazoan evolution.