Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

A comparative analysis of aerosol exposure and prevention strategies in bystander, pre-hospital, and inpatient cardiopulmonary resuscitation using simulation manikins

To evaluate aerosol exposure risk and prevention strategies during bystander, pre-hospital, and inpatient cardiopulmonary resuscitation (CPR). This study compared hands-only CPR, CPR with a surgical or N95 mask, and CPR with a non-rebreather mask at 15 L/min. 30:2 compression-ventilation ratio CPR was tested with face-mask ventilation (FMV), FMV with a high efficiency particulate air (HEPA) filter; supraglottic airway (SGA), SGA with a surgical mask, SGA with a HEPA filter, or SGA with both. Continuous CPR was tested with an endotracheal tube (ET), ET with a surgical mask, a HEPA filter, or both. Aerosol concentration at the head, trunk, and feet of the mannequin were measured to evaluate exposure to CPR personnel. Hands-only CPR with a surgical or N95 face mask coverings and ET tube ventilation CPR with filters showed the lowest aerosol exposure among all study groups, including CPR with NRM oxygenation, FMV, and SGA ventilation. NRM had a mask effect and reduced aerosol exposure at the head, trunk, and feet of the mannequin. FMV with filters during 30:2 CPR reduced aerosol exposure at the head and trunk, but increased at the feet of the mannequin. A tightly-sealed SGA when used with a HEPA filter, reduced aerosol exposure by 21.00-63.14% compared with a loose-fitting one. Hands-only CPR with a proper fit surgical or N95 face mask coverings is as safe as ET tube ventilation CPR with filters, compared with CPR with NRM, FMV, and SGA. FMV or tight-sealed SGA ventilation with filters prolonged the duration to achieve estimated infective dose of SARS-CoV-2 2.4-2.5 times longer than hands-on CPR only. However, a loose-fitting SGA is not protective at all to chest compressor or health workers standing at the foot side of the victim, so should be used with caution even when using with HEPA filters.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

Comparing the effectiveness of negative-pressure barrier devices in providing air clearance to prevent aerosol transmission

PURPOSE

To investigate the effectiveness of aerosol clearance using an aerosol box, aerosol bag, wall suction, and a high-efficiency particulate air (HEPA) filter evacuator to prevent aerosol transmission.

METHODS

The flow field was visualized using three protective device settings (an aerosol box, and an aerosol bag with and without sealed working channels) and four suction settings (no suction, wall suction, and a HEPA filter evacuator at flow rates of 415 liters per minute [LPM] and 530 LPM). All 12 subgroups were compared with a no intervention group. The primary outcome, aerosol concentration, was measured at the head, trunk, and foot of a mannequin.

RESULTS

The mean aerosol concentration was reduced at the head (p < 0.001) but increased at the feet (p = 0.005) with an aerosol box compared with no intervention. Non-sealed aerosol bags increased exposure at the head and trunk (both, p < 0.001). Sealed aerosol bags reduced aerosol concentration at the head, trunk, and foot of the mannequin (p < 0.001). A sealed aerosol bag alone, with wall suction, or with a HEPA filter evacuator reduced the aerosol concentration at the head by 7.15%, 36.61%, and 84.70%, respectively (99.9% confidence interval [CI]: -4.51-18.81, 27.48-45.73, and 78.99-90.40); trunk by 70.95%, 73.99%, and 91.59%, respectively (99.9% CI: 59.83-82.07, 52.64-95.33, and 87.51-95.66); and feet by 69.16%, 75.57%, and 92.30%, respectively (99.9% CI: 63.18-75.15, 69.76-81.37, and 88.18-96.42), compared with an aerosol box alone.

CONCLUSIONS

As aerosols spread, an airtight container with sealed working channels is effective when combined with suction devices.

[Clinical and genetic manifestations of immunodeficiency, centromeric instability, and facial anomalies syndrome: a case report and literature review]

Objective: To analyze the clinical and genetic features of immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome with a case report and literature review. Methods: The clinical data and genetic test of a girl diagnosed with ICF syndrome in the Department of Nephrology and Immunology in Qingdao Women and Children's Hospital in December 2016 were extracted and analyzed. "ICF syndrome" "immunodeficiency, centromeric instability and facial anomalies syndrome" "ICF syndrome and DNMT3B" were used as key words to search Chinese databases and Pubmed for literature until March 2018, and the literature was reviewed. Results: A female patient aged 22 months old with ocular hypertelorism and low-set ears was admitted due to recurrent infection over one year. Laboratory tests showed humoral immune deficiency with IgG<1.34 g/L, IgA<0.060 g/L, and IgM<0.179 g/L, but normal cellular immunity (total T lymphocyte 0.503, hepler T lymphocyte 0.328, cytotoxic T lymphocyte 0.166, natural killer cell 0.184, total B lymphocyte 0.276). Whole-exome sequencing revealed a de novo heterozygous splice site mutation c.922-2A>G in intron 8, and a de novo heterozygous missense mutation c.2477G>A in exon 23 of DNMT3B gene. Chromosome karyotype analysis showed 46, XX, with 64 out of 100 karyotypes showing centromere instability in chromosome 1. Five papers were found which were all in English, with total of 29 patients. Forty-three mutations were reported, including 34 missense, 2 deletion, 1 insertion, 6 splice site mutations. Eleven patients had complex heterozygosis mutations. All patients had centromere instability, humoral immune deficiency and facial dysplasia which were mainly ocular hypertelorism and low-set ears. Most patients had language and motor development delay, and a few were combined with mental retardation. Conclusions: ICF syndrome is a rare autosomal recessive primary immunodeficiency with classic clinical triad manifestations. De novo mutation of DNMT3B gene is one of etiologies according to genetic test.

Characterization and adsorption capacity of potassium permanganate used to modify activated carbon filter media for indoor formaldehyde removal

This study examined the effect of potassium permanganate (KMnO₄)-modified activated carbon for formaldehyde removal under different face velocities and different initial formaldehyde concentrations in building environment. We chose the coconut shell activated carbon due to their high density and purity. Moreover, they have a clear environmental advantage over coal-based carbons, particularly in terms of acidification potential. The chemical properties were characterized by FTIR to show the functional groups, EDS to calculate each component of their energy bands to know how the ratio is. Also, the morphology of the surface was examined with scanning electron microscopy (SEM). The BET determines specific surface area, pore size, and pore volume. It was found that where the initial formaldehyde concentration and the face velocity are low, adsorption capacity is high. The adsorption isotherms of formaldehyde on modified activated carbon are well fitted by both Langmuir and Freundlich equations. The rate parameter for the pseudo-first-order model, pseudo-second-order model, and intraparticle diffusion model was compared. The correlation coefficient of pseudo-second-order kinetic model (0.999 > R² > 0.9548) is higher than the coefficient of pseudo-first-order kinetic model (0.5785 < R² < 0.8755) and intraparticle diffusion model (0.9752 < R² < 0.9898). Thus, pseudo-second-order kinetic model is more apposite to discuss the adsorption kinetic in this test, and the overall rate of the modified activated carbon adsorption process appears to be influenced by more than one step that is both the intraparticle diffusion model and membrane diffusion.

Analysis of metabolic profiles of generalized aggressive periodontitis

BACKGROUND AND OBJECTIVE

The specific pathogenesis of generalized aggressive periodontitis (GAgP) has not yet been clarified, and few studies have focused on the association between GAgP and metabolomics. To elucidate the roles of metabolic profiles in the status of GAgP, this study aimed to identify the differential metabolic profiles between patients with GAgP and healthy controls using an untargeted metabolomic profiling method.

MATERIAL AND METHODS

Serum and gingival crevicular fluid samples were collected from healthy controls (n = 20) and patients with GAgP (n = 20) in this cross-sectional study. The relative levels of biomarkers in the samples were measured by gas chromatography-mass spectrometry. Principal components analysis and orthogonal partial least-squares discriminant analysis were used for statistical analysis. Metabolites were analysed qualitatively using the FiehnLib and NIST databases. Full-mouth probing depth and clinical attachment loss were recorded as indexes of periodontal disease.

RESULTS

A total of 349 metabolites were qualitatively detected in the gingival crevicular fluid samples, and 200 metabolites were detected in the serum samples. Compared with healthy controls, patients with GAgP showed significant increases in serum urea and allo-inositol levels. In contrast, glutathione, 2,5-dihydroxybenzaldehyde, adipic acid and 2-deoxyguanosine levels were decreased in patients with GAgP. In the gingival crevicular fluid samples, noradrenaline, uridine, α-tocopherol, dehydroascorbic acid, xanthine, galactose, glucose-1-phosphate and ribulose-5-phosphate levels were increased in patients with GAgP, while thymidine, glutathione and ribose-5-phosphate levels were decreased.

CONCLUSION

The metabolomics analysis by gas chromatography-mass spectrometry is an effective and minimally non-invasive way to differentiate the metabolites characteristic of patients with GAgP. Both serum and gingival crevicular fluid metabolomics are significantly different between patients with GAgP and healthy controls. These metabolic profiles have great potential in detecting GAgP and helping to understand its underlying mechanisms.

Validation of Contamination Control in Rapid Transfer Port Chambers for Pharmaceutical Manufacturing Processes

There is worldwide concern with regard to the adverse effects of drug usage. However, contaminants can gain entry into a drug manufacturing process stream from several sources such as personnel, poor facility design, incoming ventilation air, machinery and other equipment for production, etc. In this validation study, we aimed to determine the impact and evaluate the contamination control in the preparation areas of the rapid transfer port (RTP) chamber during the pharmaceutical manufacturing processes. The RTP chamber is normally tested for airflow velocity, particle counts, pressure decay of leakage, and sterility. The air flow balance of the RTP chamber is affected by the airflow quantity and the height above the platform. It is relatively easy to evaluate the RTP chamber′s leakage by the pressure decay, where the system is charged with the air, closed, and the decay of pressure is measured by the time period. We conducted the determination of a vaporized H₂O₂ of a sufficient concentration to complete decontamination. The performance of the RTP chamber will improve safety and can be completely tested at an ISO Class 5 environment.

Validation of cross-contamination control in biological safety cabinet for biotech/pharmaceutical manufacturing process

For class II, type A2 biological safety cabinets (BSC), NSF/ANSI Standard 49 should be conformed in cabinet airflow velocity derivation, particle contamination, and aerodynamic flow properties. However, there exists a potential problem. It has been built that the cabinet air flow stabilize is influenced by the quantity of downflow of air and the height above the cabinet exhaust opening. Three air downflow quantities were compared as an operating apparatus was placed from 20 to 40 cm above the bench of the cabinet. The results show that the BSC air downflow velocity is a function of increased sampling height, displaying that containment is improvingly permitted over product protection as the sampling height decreases. This study investigated the concentration gradient of particles at various heights and downflow air quantity from the bench of the BSC. Experiment results indicate that performance near the bench was better than in the rest of the BSC. In terms of height, the best cleanliness was measured at a height of 10 cm over the bench; it reduced actually with add in height. The empirical curves accommodate, founded on the concentration gradient of particle created was elaborated for evaluating the particle concentration at different heights and downflow air quantity from the source of the bench of the BSC. The particle image velocimetry system applied for BSC airflow research to fix amount of airflow patterns and air distribution measurement and results of measurements show how obstructions can greatly influence the airflow and contaminant transportation in a BSC.

Factors affecting the use of anti-amoebiasis protective measures among Taiwan immigrants returning to amoebiasis-endemic regions

OBJECTIVE

To investigate the predictors of use of anti-amoebiasis protective measures (AAPMs) among Taiwan immigrants returning to their country of origin, using the Health Belief Model (HBM) to guide the investigation.

DESIGN

Cross-sectional study.

METHODS

Between March and May 2011, all permanent immigrants originating from amoebiasis-endemic countries who received services at the immigrant service centres in Taipei or Tainan and who reported that they had returned to their country of origin within the past five years were enrolled in the study. A structured questionnaire containing questions on sociodemographic characteristics and items related to the constructs of the HBM was used as the data collection instrument.

RESULTS

Complete information was collected from 384 immigrants, with a response rate of 80% (384/480). The mean age of the subjects was 38.4 years (standard deviation 10.6 years). The majority (70%) of participants did not receive travel information through a pretravel consultation, and more than 17% reported that they did not use measures to prevent amoebiasis. Multiple regression analyses revealed that Chinese proficiency, pretravel consultation and lower barriers to using protective measures were significantly associated with the use of AAPMs during return trips to country of origin (R(2) = 0.45; F = 77.5; P < 0.001).

CONCLUSION

The HBM significantly predicted the use of AAPMs in this study. A high proportion of immigrants did not use appropriate AAPMs when they returned to their country of origin. Educational approaches should be targeted at immigrants originating from amoebiasis-endemic regions who return to their country of origin.

Numerical study on the dispersion of airborne contaminants from an isolation room in the case of door opening

A negative pressure isolation room is built to accommodate and cure patients with highly infectious diseases. An absolutely airtight space effectively prevents infectious diseases from leaking out of the isolation room. Opening the door leads to a breakdown in isolation conditions and causes the dispersion of infectious air out of the isolation room. Extensively employed to manage smoke in cases of fires at subway and highway tunnels, a concept of controlling airflow is applied to the study. This study proposes a design of ventilation system to control air flow rate for containing airborne contaminant and preventing its spread to the adjacent rooms when the door to the isolation room is opened and closed. This paper employs computational fluid dynamics (CFD) as a more effective approach to examine the concentration maps of airborne contaminants and the airflow patterns of room air and discuss the influence of temperature differences between two rooms on airborne dispersion. Results show that an air velocity above 0.2 m/s via a doorway effectively prevents the spread of airborne contaminants out of the isolation room in the state of door opening.

Workplace smoking related absenteeism and productivity costs in Taiwan

OBJECTIVE

To estimate productivity losses and financial costs to employers caused by cigarette smoking in the Taiwan workplace.

METHODS

The human capital approach was used to calculate lost productivity. Assuming the value of lost productivity was equal to the wage/salary rate and basing the calculations on smoking rate in the workforce, average days of absenteeism, average wage/salary rate, and increased risk and absenteeism among smokers obtained from earlier research, costs due to smoker absenteeism were estimated. Financial losses caused by passive smoking, smoking breaks, and occupational injuries were calculated.

RESULTS

Using a conservative estimate of excess absenteeism from work, male smokers took off an average of 4.36 sick days and male non-smokers took off an average of 3.30 sick days. Female smokers took off an average of 4.96 sick days and non-smoking females took off an average of 3.75 sick days. Excess absenteeism caused by employee smoking was estimated to cost USD 178 million per annum for males and USD 6 million for females at a total cost of USD 184 million per annum. The time men and women spent taking smoking breaks amounted to nine days per year and six days per year, respectively, resulting in reduced output productivity losses of USD 733 million. Increased sick leave costs due to passive smoking were approximately USD 81 million. Potential costs incurred from occupational injuries among smoking employees were estimated to be USD 34 million.

CONCLUSIONS

Financial costs caused by increased absenteeism and reduced productivity from employees who smoke are significant in Taiwan. Based on conservative estimates, total costs attributed to smoking in the workforce were approximately USD 1032 million.

Clinical comparison of high-dose interferon-alpha2b with or without ribavirin for treatment of interferon-relapsed chronic hepatitis C

BACKGROUND

Interferon a with ribavirin combination therapy is effective but still unsatisfactory in the treatment of patients with interferon-relapsed chronic hepatitis C.

AIMS

To compare, in a randomized, double blind, placebo-controlled study, high-dose interferon-alpha2b with or without ribavirin in the treatment for interferon-relapsers.

PATIENTS

A total of 52 patients with interferon-relapsed chronic hepatitis C were randomly assigned to receive 24-week treatment with interferon-alpha2b (6 MU three times per week) combined with either ribavirin (1,000 to 1,200 mg per day) or a matched placebo and then followed for an additional 24 weeks.

METHODS

Hepatitis C virus RNA was detected by reverse-transcription polymerase chain reaction. For determining viral concentration, the commercial bDNA Quantiplex hepatitis C virus-RNA 2.0 assay was used. Genotyping was performed by reverse hybridization assay

RESULTS

At the end of treatment, no detectable hepatitis C virus RNA levels were observed in 92% (24/26) of patients on interferon alpha2b/ribavirin and 81% (21/26) of patients on interferon alpha2b/placebo. At the end of the follow-up, a higher sustained virological response rate was seen in patients treated with interferon alpha2b/ribavirin than those treated with interferon alpha2b/placebo (69% vs 23%, p < 0.001). Patients with either initially high levels of viral concentration or with genotype 1 responded poorly. Patients who received interferon-alpha2b/ribavirin treatment and in whom no hepatitis C virus RNA was detected at 4th week after treatment had 90% chance to achieve sustained virological response.

CONCLUSIONS

High-dose interferon-alpha2b plus ribavirin treatment is highly effective in interferon-relapsed patients.

Demographics and social security

"This paper considers the welfare implications of the interactions between demographic changes and social security in an overlapping generations model in which retirement decisions are endogenous. Both a pay-as-you-go system and an actuarially-fair system are examined." The geographical focus is on the United States.

Induced sputum derives from the central airways: confirmation using a radiolabeled aerosol bolus delivery technique

Indirect evidence suggests that induced sputum derives from the surfaces of the bronchial airways. To confirm this experimentally, we employed a radiolabeled aerosol bolus delivery technique that preferentially deposits aerosol in the central airways in humans. We hypothesized that there would be significantly more radioactivity recovered in an induced sputum sample, and greater airways clearance of radiolabeled particles, immediately after a central versus peripheral airways deposition. Ten healthy volunteers underwent radiolabeled aerosol deposition ((99m)Tc sulfur colloid particles) to the central and peripheral airways on separate occasions followed immediately by induced sputum or no sputum (control), while seated in front of a gamma camera. Radioactivity was measured in the selected sputum sample, processed cell pellet, and supernatant fraction. Significantly more radioactivity was present in all portions of the sputum sample after central versus peripheral airways deposition (i.e., selected sample: 15,607 counts +/- 2,985 versus 943 counts +/- 298, p = 0.001). Clearance from the whole lung was significantly greater 40 min after central versus peripheral airways deposition (48 +/- 3% versus 5 +/- 1%, p = 0.0001). Compared with control, induced sputum greatly enhanced clearance after central deposition (48 +/- 3% versus 11 +/- 6%, p = 0.0001), but not after peripheral deposition (5 +/- 1% versus 3 +/- 0.8%). These results provide direct evidence that induced sputum derives from the central airways with little or no contribution from the peripheral airways.

GB virus-C/hepatitis G virus infection in a hepatitis C virus endemic village: prevalence in residents with low educational attainment and frequent recovery in females

AIMS/BACKGROUND

GB virus-C/hepatitis G virus (HGV) is a newly identified flavivirus, which may share the same mode of transmission as hepatitis C virus (HCV). The aim of this study was to investigate associated factors of HGV infection and clearance in a HCV endemic village in southern Taiwan.

METHODS

Five hundred and ninety-four residents of a village in southern Taiwan were enrolled for hepatitis virus screening. Clinical features were recorded and a questionnaire addressing the possible routes of transmission was filled in by the participating residents.

RESULTS

The prevalence of antibody to hepatitis C virus and hepatitis B surface antigen in the 594 residents was 70.7% and 19.5% respectively. Of the 399 residents tested for HGV RNA, GB virus-C/Hepatitis G virus envelop 2 protein (HGV-E2) antibody, and HCV RNA, the prevalence was 13.5%, 25.3%, 53.1% respectively. Multivariate logistic regression analysis showed that low educational attainment was associated with HGV infection, old age and low educational attainment were associated with HCV infection, and female gender was associated with HGV clearance. Alanine aminotransferase (ALT) values were significantly higher for residents with HCV infection alone, HBV infection alone, and co-infection of HCV and HBV than for those without HBV, HCV, and HGV infection. There were no differences in ALT values between subjects with HGV infection alone and those without HBV, HCV, and HGV infections. Residents with co-infection of HGV and HBV, or HGV and HCV had ALT values similar to those with HBV or HCV infection alone.

CONCLUSION

HGV infection is common in the HCV endemic village. The transmission of HGV is closely related to low educational attainment. HGV clearance is frequently encountered in females. Co-infection of HGV does not compound hepatocellular inflammation.

An autoradiographic assessment of epithelial cell proliferation and post-natal maturation of the tracheal epithelium in infant ferrets

The tracheal epithelium of infant ferrets undergoes rapid postnatal maturation over the first month of life to achieve the pseudostratified columnar configuration characteristic of the large airways of other mammals. We have used in vivo pulsing with tritiated thymidine ((3)HT) to elicit autoradiographic labeling of cells synthesizing nucleic acids in order to characterize more fully the contribution to development of different cell types comprising the nascent epithelial layer during this period of rapid growth. These studies indicate that two distinct populations of epithelial cells possess proliferative potential and contribute to the establishment of the mature adult epithelial layer. These investigations further confirm the mitotic potential of basal cells during a period of rapid postnatal growth and development of the tracheal epithelial layer. These studies also document the contribution to early airway development by non-ciliated cells, which predominate on the luminal border of the ferret trachea at birth. The temporal and histologic patterns of airway epithelial maturation during post-natal life in the ferret as contained in this study exhibit similarities to those which occur with recovery from injury by infection and irritant exposure in mature airways. Thus, the characterization of epithelial cell compartments having proliferative potential may provide insights into the mechanisms whereby normal airway epithelial organization is established and maintained during development as well as the possible recapitulation of these mechanisms during times of epithelial regeneration following injury.

Regulation of CBP-mediated transcription by neuronal calcium signaling

The transcription factor CREB is involved in mediating many of the long-term effects of activity-dependent plasticity at glutamatergic synapses. Here, we show that activation of NMDA receptors and voltage-sensitive calcium channels leads to CREB-mediated transcription in cortical neurons via a mechanism regulated by CREB-binding protein (CBP). Recruitment of CBP to the promoter is not sufficient for transactivation, but calcium influx can induce CBP-mediated transcription via two distinct transactivation domains. CBP-mediated transcription is stimulus strength-dependent and can be induced by activation of CaM kinase II, CaM kinase IV, and protein kinase A, but not by activation of the Ras-MAP kinase pathway. These observations indicate that CBP can function as a calcium-sensitive transcriptional coactivator that may act as a regulatory switch for glutamate-induced CREB-mediated transcription.

Renal abscess: early diagnosis and treatment

The purpose of this study was to identify initial clinical characteristics that can lead to early diagnosis of renal abscess in the emergency department and predict poor prognosis. A retrospective review of 88 renal abscess patients, from April 1979 through January 1996, was conducted. Patients were categorized into two groups. In group 1, renal abscess was diagnosed by an emergency physician, whereas in group 2 renal abscess was not diagnosed by an emergency physician. Clinical characteristics included demographic data, predisposing medical problems, duration of illness before diagnosis, time spent in hospital diagnosis, initial signs and symptoms, laboratory tests, and radiology studies that may have been useful in the early diagnostic regimes. Clinical factors were also analyzed for their value in predicting poor prognosis. The mean age of 88 patients with renal abscess was 59.8 years. The most common predisposing disorder was diabetes mellitus, followed by renal calculi and ureteral obstruction. The duration of diagnosis by emergency physicians was shorter for group 1 patients (1.2 +/- .4 v group 2, 2.8 +/- 2.9 days; P < .01) and the blood urea nitrogen level was higher in group 1 (55.7 +/- 42.2 mg/dL, v group 2, 33.5 +/- 33.5 mg/dL; P = .02). In the early diagnosis of renal abscess, emergency physicians should focus on patients who have predisposing disorders, ie, diabetes mellitus, renal stones, immunosuppression, longer duration of symptoms of urinary tract infection, and renal failure, who should promptly be investigated with ultrasound in the emergency department. The cure rate after treatment with routine antibiotics plus percutaneous drainage was 64%. This therapy is recommended for initial treatment. Poor prognosis is associated with elderly patients with lethargy and with elevation of the serum blood urea nitrogen level.

Elderly use of the ED in an Asian metropolis

To compare emergency department (ED) use by elderly patients (age 65 yrs or older) with that by younger adult patients (age 15-64 yrs), a prospective consecutive chart review study was conducted from August 1, 1995 through May 31, 1996 in eight designated hospitals in Taipei city (which has 2.6 million residents, 8.4% of whom are 65 yrs or older). Patient age, sex, mode of arrival, living status, triage category, advanced life support (ALS) eligibility, referral, confinement to bed, intensive care unit (ICU) admission, impression, trauma mechanism, and disposition were recorded and compared between the two groups. Of 27,765 adult emergency patients studied during the 10 months, 24% were elderly. The elderly were more likely to be ambulance cases, of high acuity and ALS eligibility, living alone, bed-ridden, and ICU cases (19.4% v 10.5%, 14.8% v 5.5%, 14.7% v 4.3%, 9.7% v 4.1%, 16% v 1.1%, and 4.0 v 1.1%, respectively). The three leading illnesses in the elderly were cerebral vascular accident (6.6%), cancer (5.6%), and cardiovascular disease (5.6%), and the two most common trauma mechanisms were trip (fall from the same level surface) (57.2%) and traffic accident (20.7%). Twenty-seven percent and 22.7% of elderly were disposed to admission and observation, respectively, compared with the 10.9% and 11.4% of the younger patients. Elderly patients have significantly different and more severe presentations to the ED compared with younger adults.

Establishing the norm of Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) in Chinese infants

The Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) has been recommended as a useful diagnostic tool for cognitive delay. To provide wider application of this instrument as a general screening tool for pediatricians, a normative percentile graph from a large convenience sample of Chinese infants has been established. The effects of environmental factors on early language and adaptive development were also analyzed. A total of 402 normal infants aged 4 to 36 months attending well-child clinics were recruited. These infants were from all socioeconomic strata, and half were bilingual with Mandarin and Taiwanese. Grandmothers were the chief caretakers or co-caretakers in 28% of this population. The milestones were attained in a sequential and orderly fashion. In contrast to the adaptive ability, there was a wide variation in language acquisition between age 12 and 24 months. Multiple stepwise regression of demographic and environmental factors revealed that age was the main variance in CAT score (P = 0.0001). In CLAMS score, however, age and caretakers were the significant predictors (P = 0.0001). Infants cared for by both mothers and grandmothers had higher CLAMS score by two months over those cared by mothers only (P = 0.001). Those cared for by grandmothers only had lower language score than those by mothers only, though without statistical significance (P = 0.05). Bilingualism, birth order, numbers of siblings, familial structures, and parental socioeconomic status had no effect on early development.

Emergency medical resource use in Taipei city

BACKGROUND

It is a worldwide trend to serve emergency patients at emergency department (EDs) staffed by board-certified emergency physicians (EPs). The question arises as to how many EPs are cost effective? This cannot be answered until utilization of emergency resources in the community is explored, so that appropriate plans for efficient ED use, staffing and training of EPs can be made.

METHODS

A prospective randomized chart-review study was conducted from August 1, 1995, until May 31, 1996, in the EDs of eight large hospitals in Taipei City. These included Chung-Hsin Municipal Hospital (CHH), Chung-Shiaw Municipal Hospital (CSH), Ho-Ping Municipal Hospital (HPH), Jen-Ai Municipal (JAH), Mackay Memorial Hospital (MMH), Tri-Service General Hospital (TSGH), Veterans General Hospital-Taipei (VGH-T) and the Yang-Ming Municipal Hospital (YMH).

RESULTS

Of 37,889 cases reviewed, the average daily ED census at each hospital was: VGH-T 198; TSGH 148; MMH 224; HPH 62; YMH 84; CHH 41; JAH 102; and CSH 139. At MMH, pediatric patients comprised 38.8% of emergency patients and the elderly comprised 49% of patients of VGH-T. The average age of patients was 56 years in VGH-T and 40 years in other hospitals. There were 71 (11.1%) pediatric patients and 3,087 (1.8%) adult patients taken to hospital by an emergency medical services (EMS) ambulance. A total of 176 pediatric and 2,230 (8.1%) adult patients belonged to triage categories 1 and 2. VGH-T had a much higher percentage of triage 1 and 2 patients (769, 13%) than the other hospitals. A total of 30.7% of pediatric and 17.4% of adult patients were classified as triage 4 (pseudoemergency). Patients requiring advanced life support, referral cases and patients requiring an intensive care unit (ICU) bed accounted for 1.1%, 0.9% and 0.6% of pediatric patients, and 6.8%, 3.4% and 1.8% of adult patients, respectively. These figures increased to 11.1%, 7.7% and 3.5%, respectively, in VGH-T. Among patients requiring ICU admission, 30% of pediatric and 53% of adult patients were not admitted on presentation to the ED. Of 10,099 children and 27,555 adults who were evaluated for case disposition, 651 (6.5%) and 4,061 (14.7%), respectively, were considered for admission. Among these 542 (83.3%) and 2,894 (71.3%), respectively, were admitted.

CONCLUSIONS

VGH-T is a favorable training ground for EPs due to its high volume of adult and elderly, advanced life support eligible, ICU and high acuity patients. MMH is an ideal place for training in pediatric emergency medicine. Utilization of the 119 emergency response system is low. The number of patients with high acuity triage in Taipei City is low. However, Taipei City faces a shortage of acute care beds, especially ICU beds.

Regional deposition of inhaled particles in human lungs: comparison between men and women

We measured detailed regional deposition patterns of inhaled particles in healthy adult male (n = 11; 25 +/- 4 yr of age) and female (n = 11; 25 +/- 3 yr of age) subjects by means of a serial bolus aerosol delivery technique for monodisperse fine [particle diameter (Dp) = 1 micron] and coarse aerosols (Dp = 3 and 5 micron). The bolus aerosol (40 ml half-width) was delivered to a specific volumetric depth (Vp) of the lung ranging from 100 to 500 ml with a 50-ml increment, and local deposition fraction (LDF) was assessed for each of the 10 local volumetric regions. In all subjects, the deposition distribution pattern was very uneven with respect to Vp, showing characteristic unimodal curves with respect to particle size and flow rate. However, the unevenness was more pronounced in women. LDF tended to be greater in all regions of the lung in women than in men for Dp = 1 micron. For Dp = 3 and 5 micron, LDF showed a marked enhancement in the shallow region of Vp </= 200 ml in women compared with men (P < 0.05). LDF in women was comparable to or smaller than those of men in deep lung regions of Vp > 200 ml. Total lung deposition was comparable between men and women for fine particles but was consistently greater in women than men for coarse particles regardless of flow rates used: the difference ranged from 9 to 31% and was greater with higher flow rates (P < 0.05). The results indicate that 1) particle deposition characteristics differ between healthy men and women under controlled breathing conditions and 2) deposition in women is greater than that in men.

Continuous flumazenil infusion in preventing complications arising from severe benzodiazepine intoxication

A prospective, randomly controlled study was conducted to test the effect of continuous flumazenil infusion in preventing complications arising from severe benzodiazepine (BZ) intoxication. Patients who were believed to be suffering benzodiazepine intoxication and whose Glasgow Coma Scale (GCS) score was below 10 were enrolled after showing a clear-cut response to flumazenil 0.5 or 1 mg (an improvement by 4 or more on the GCS). The patients were consecutively enrolled and randomized into two groups: a continuous infusion group (CI, n = 50) who were immediately given flumazenil 0.5 mg/h for 5 hours, and a control group (CIN, n = 50). Age, sex, incidence of underlying disease, GCS score at several time points, and complication rate were compared in the two groups. Although the CI group had a higher GCS score at most time points, the complication rate did not significantly differ between the two groups (14 of 36 in the CI group v 12 of 38 in the CIN group, P = .684). A greater incidence of underlying disease and an older age seemed to contribute to the higher complication rates in both groups. Several patients (in both groups) resedated into deeper coma after showing an initial response to flumazenil or after the cessation of flumazenil infusion. For severe BZ intoxication, treatment with flumazenil infusion should still be considered skeptically and should not be recommended as routine management BZ-intoxicated patients with an underlying disease, an older age, and resedation into a deep comatose state after showing an initial response to flumazenil should be treated in an intensive care unit.

Identification of a signaling pathway involved in calcium regulation of BDNF expression

A signaling pathway by which calcium influx regulates the expression of the major activity-dependent transcript of BDNF in cortical neurons has been elucidated. Deletion and mutational analysis of the promoter upstream of exon III reveals that transactivation of the BDNF gene involves two elements 5' to the mRNA start site. The first element, located between 72 and 47 bp upstream of the mRNA start site, is a novel calcium response element and is required for calcium-dependent BDNF expression in both embryonic and postnatal cortical neurons. The second element, located between 40 and 30 bp upstream of the mRNA start site, matches the consensus sequence of a cAMP response element (CRE) and is required for transactivation of the promoter in postnatal but not embryonic neurons. The CRE-dependent component of the response appears to be mediated by CREB since it is part of the complex that binds to this CRE, and since dominant negative mutants of CREB attenuate transactivation of the promoter. A constitutively active mutant of CaM kinase IV, but not of CaM kinase II, leads to activation of the promoter in the absence of extracellular stimuli, and partially occludes calcium-dependent transactivation. The effects of CaM kinase IV on the promoter require an intact CRE. These mechanisms, which implicate CaM kinase IV and CREB in the control of BDNF expression, are likely to be centrally involved in activity-dependent plasticity during development.

The applicability of the theory of planned behavior to the intention to quit smoking across workplaces in southern Taiwan

An examination of the applicability of the theory of planned behavior (TPB) to the intention to quit smoking across workplaces was conducted. Subjects were randomly selected from three workplaces in southern Taiwan. Those from a large public steel-manufacturing company were used for model building, and those from two private auto-parts-manufacturing companies served to cross-validate the model. Eligible subjects were divided into three study samples: a learning sample and two test samples. Three predictors--priority of quitting, past behavior (measured as previous quit attempt), and habit (measured as nicotine dependence)--were added to the TPB model. The results of this study show that TPB based on the learning sample fit well in another sample from the same workplace but poorly in other workplaces. When priority of quitting and past behavior were added to the TPB model, prediction to other workplaces significantly improved. Habit had no significant contribution to the intention to quit in the TPB model. Detailed discussions of the results are provided.

Employers' awareness and compliance with occupational health and safety regulations in Taiwan

An investigation of employers' awareness and compliance with occupational health and safety (OHS) regulations was conducted in a representative group of employers randomly selected from the manufacturing industry in Taiwan. A total of 1,003 employers were interviewed by trained public health personnel. Ten questions related to perceptions of general OHS and five practices on OHS regulations were measured. The results of this study show that the employers were better aware of their responsibility for posting safety warnings, personal protection and providing safety and health equipment. They were less aware of their responsibility in minimizing injuries and accidents in the workplace and in not hiring someone who was found unfit for a certain job from pre-employment physical examination. Less than half of employers knew about regulations of environmental monitoring and even fewer had heard of Material Safety Data Sheets. Level of education and size of the plant were highly associated with employers' awareness of OHS and the awareness was the most significant predictor in the five practices of OHS regulations in this study. Promotion of employers' awareness of OHS in small sized industries in particular, is warranted to enhance better compliance, and a focus for these efforts is identified by this investigation.

Connexin 26 expression in human and ferret airways and lung during development

Coordinated microscopic and molecular biological studies were used to document gap junction expression during postnatal development in ferret tracheal epithelium and lung and in fetal and adult human airway and lung. Expression of connexin 26 (Cx26) in the ferret airways was limited to the epithelial layer and was observed only during the newborn interval. In contrast, we found Cx26 expressed in the alveolar epithelium of the ferret lung by in situ hybridization, Northern blotting, RT-PCR amplification, and immunocytochemical labeling at all ages examined. This finding was further confirmed by documentation of gap junctional plaques upon ultrastructural examination of freeze-fracture replicas of adult ferret lung tissue. Parallel studies of developing human fetal lung and airway suggested connexin expression in the airways only in the first trimester but, as in the ferret, persistent expression was observed in both fetal and adult lung. These studies suggest that the transient expression of Cx26 is a reliable early indicator of airway epithelial development and differentiation in the airways. In contrast, Cx26 expression persists throughout life in the lung, suggesting that gap junctions serve more perennial intercellular communication functions in the peripheral lung.

Arterial oxygen desaturation during emergent nonsedated upper gastrointestinal endoscopy in the emergency department

A prospective study was conducted to see whether emergent esophagogastroduodenoscopy (EGD) in patients with active upper gastrointestinal (GI) bleeding is associated with more oxygen desaturation than nonemergent EGD. Emergent EGD was performed in the study patients with active upper GI bleeding. Nonemergent EGD was performed in the control patients. Determination of oxygen saturation (Sao2) was measured by pulse oximeter. A decrease in Sao2 of > 4% was more frequent in the study patients (26%, 13 of 50) than in controls (6%, 3 of 50) (P < .01). During EGD, mean oxygen saturation decreased significantly in both groups of patients. After EGD, mean oxygen saturation did not recover toward the pre-endoscopy insertion level in the study group (P < .01). A linear association was found that oxygen desaturation = 5.46 + 0.15 (status) -0.06 (baseline oxygen saturation). Emergent EGD for active upper GI bleeding in the emergency department tends to be associated with more frequent significant oxygen desaturation than nonemergent EGD. Continuous oxygen supplementation and oxygen saturation monitoring may be used during emergent nonsedated EGD in the emergency department.

Direct surgery of carotid cavernous fistulae and dural arteriovenous malformations of the cavernous sinus

OBJECTIVE

To save the patency of the internal carotid artery (ICA) during the treatment of carotid cavernous fistulae or cavernous sinus dural arteriovenous malformations, direct surgery of the cavernous sinus after failure of endovascular treatment was attempted in this study.

METHODS

A total of 78 patients with carotid cavernous fistulae or cavernous sinus dural arteriovenous malformations were treated. Obliteration of the fistulous rent and preservation of the ICA were the therapeutic goals. All patients, except one in whom acute bleeding occurred, received endovascular treatment as the first treatment. In 18 (23.4%) of these 77 patients, it was not possible to obliterate the fistulous rents without sacrificing the ICAs. The 18 patients and the 1 patient with acute bleeding underwent direct surgery to open the cavernous sinus.

RESULTS

Various methods, including suturing or clipping the fistulae, sealing the fistulae with fascia and acrylate glue, and packing the cavernous sinus were applied. In each of three complicated cases, the cavernous segment of the ICA was trapped and an intracranial bypass from the petrous segment to the supraclinoid segment was performed. There was nor mortality, and the most common morbidity was transient oculomotor palsy, which occurred in eight patients. Follow-up angiography revealed that the ICAs or bypass grafts were thrombosed in 5 of the 19 patients who had undergone surgery.

CONCLUSION

In this series, the overall ICA patency rate of patients who underwent embolization and surgery was 94%, and the obliteration rate of the fistulae was 100%. Direct surgery of the cavernous sinus as a complimentary treatment of embolization can increase the preservation rate of the ICA.

Psoas abscess: making an early diagnosis in the ED

The variable and nonspecific presentations of psoas abscess, as well as its infrequent incidence in the emergency department (ED), can result in delayed diagnosis or misdiagnosis. Previous reports have not discussed the diagnostic difficulties of psoas abscess from the viewpoint of emergency physicians (EPs), especially in light of the widespread use of ED ultrasonography. This report describes a 1-year experience between November 1993 and October 1994, during which 10 ED patients were diagnosed to have psoas abscess; in 7 cases, diagnoses were established in the ED. Patients' mean age was 64.6 years (range, 46 to 76). Pain was the most frequently encountered symptom (80%), with 5 patients (50%) complaining of flank pain. The triad of fever, flank pain, and limitation of hip movement, which is specific for psoas abscess, was present only in 3 patients (30%). The mean duration of symptoms was 10.6 days (range, 1 to 30 days). The mean time spent to establish the diagnosis was 1.7 days (range, 0 to 7 days). The diagnosis of psoas abscess was established by ultrasound in 6 patients, by computed tomography (CT) in 3 patients, and by surgery in 1 patient. Four patients who presented with either sepsis and nonspecific abdominal/flank pain or sepsis and thigh swelling were diagnosed to have psoas abscess by ultrasound performed by EPs. Only 3 patients were admitted to the ED with an initial diagnosis of psoas abscess. The remaining 7 had the following initial ED diagnoses: 2, fever of unknown origin; 2, septic shock; 1, shock; 1, sepsis; and 1, peritonitis. All but one had manifestations of sepsis. Two patients died of septic shock; these two patients had failed to be drained well. This report also includes a discussion of the role of EPs and ultrasonography in the diagnosis of psoas abscess. With their alertness and their expertise in ultrasonographic techniques, EPs can make an immediate diagnosis and arrange an early drainage procedure. For patients with sepsis of unknown origin, prolonged fever of unknown origin, and some specific manifestations suggestive of psoas abscess, the screening ultrasound should scan not only abdominal solid organs but also peritoneal cavity and retroperitoneal space. In addition, a flow chart is presented for facilitating the diagnosis of psoas abscess in the ED.

Assessment of regional deposition of inhaled particles in human lungs by serial bolus delivery method

Detailed regional deposition of inhaled particles was investigated in young adults (n = 11) by use of a serial bolus aerosol delivery technique. A small bolus (45 ml half-width) of monodisperse aerosols [1-, 3-, and 5-microns particle diameter (Dp)] was delivered sequentially to a specific volumetric depth of the lung (100-500 ml in 50-ml increments), while the subject inhaled clean air via a laser aerosol photometer (25-ml dead volume) with a constant flow rate (Q = 150, 250, and 500 ml/s) and exhaled with the same Q without a pause to the residual volume. Deposition efficiency (LDE) and deposition fraction in 10 local volumetric regions and total deposition fraction of the lung were obtained. LDE increased monotonically with increasing lung depth for all three Dp. LDE was greater with smaller Q values in all lung regions. Deposition was distributed fairly evenly throughout the lung regions with a tendency for an enhancement in the distal lung regions for Dp = 1 micron. Deposition distribution was highly uneven for Dp = 3 and 5 microns, and the region of the peak deposition shifted toward the proximal regions with increasing Dp. Surface dose was 1-5 times greater in the small airway regions and 2-17 times greater in the large airway regions than in the alveolar regions. The results suggest that local or regional enhancement of deposition occurs in healthy subjects and that the local enhancement can be an important factor in health risk assessment of inhaled particles.

Longitudinal distribution of ozone absorption in the lung: simulation with a single-path model

A one-dimensional unsteady state diffusion model was used as a basis for simulating the absorption (lambda), breakthrough (V(B)), and dispersion (sigma2) of inhaled ozone boluses as a function of penetration (V(P)) into intact human lungs. The model idealized the respiratory system as a single equivalent tube with cross-sectional and surface areas that varied as a function of longitudinal position. Longitudinal gas transport in the lumen of the equivalent tube occurred by the joint action of bulk flow and a dispersion coefficient, D. Lateral absorption between respired gas and the tube wall was characterized by an overall mass transfer coefficient, K. By inputting published values of anatomic dimensions scaled to a 160-ml conducting airway volume, D values previously reported for inert insoluble gases, and K values equal to gas-phase transfer coefficients determined in physical lung models, a reasonable simulation of the lambda-V(P) distribution measured at a 250 ml/sec respiratory flow was obtained. Simulations of the corresponding V(B)-V(P) and sigma2-V(P) distributions both exhibited the correct shapes but underestimated the actual values. Although the addition of an estimated tissue resistance to K resulted in a poorer simulation of the data, an increase in conducting airway volume from a value of 160 ml estimated by the subjects' CO2 dead space to a value of 200 ml substantially improved the V(B)-V(P) and sigma2-V(P) simulations without sacrificing the quality of the lambda-V(P) simulation. We conclude that the inclusion of a tissue diffusion resistance is not necessary to properly simulate bolus inhalation data during quiet breathing, but a reliable measurement of conducting airway volume is crucial.

Analysis of prehospital ALS cases in a rural community

BACKGROUND

An Emergency Medical Services (EMS) system containing the advanced life support (ALS) and manned with paramedics, is developing in many countries in view of the importance of prehospital ALS skills on ALS eligible patients, although previous studies have only revealed that a meager need for ALS in urban community. The purpose of this study is to understand the real demand of ALS in a rural community, so that a well organized and cost-effective EMS system can be developed in this country.

METHODS

An EMS system with a single tiered response configuration, using firefighters to give basic prehospital care, stored in computer with some necessary informations was established in Ilan County. Cases with ALS from January 1993 through December 1994 were retrieved from the computer. The ones truely eligible for ALS were reconfirmed and analized in terms of neurological outcome while discharging from hospital, sex, age, response time, time spent on scene, transportation time, as well as whether the cases were trauma or medically induced.

RESULTS

Of 11352 cases collected during 731 study days, 594(5.28%) ALS eligible cases (including 211 DOA and 383 nonDOA) were studied. Of 211 DOA, 103(48%) were caused by trauma. The response time, time spent on scene and transportation time in ALS and DOA cases were 5.5min., 4.7min., 13.6min., and 5.6min., 5.6min., and 15.7min., respectively. Of 211 cases of trauma (55% of total ALS cases), traffic accident accounted for 46%. Altered mental status and chest pain or tightness made of 90% of medical induced ALS cases. Five percent of patients felt worsening of condition during transit. One third of patients seemed to experience a bad outcome.

CONCLUSIONS

Based on the characteristics of low demand for ALS services, more than half trauma-induced ALS cases, acceptable response time, short transportation time, extremely few medically-induced DOA cases, and quite a poor outcome in the setting of limited prehospital care, a unique EMS system different from that in the United States or in the urban area is needed in the rural area.

Outcomes in severely ill patients transported without prehospital ALS

Because of the debate regarding the impact of advanced life support (ALS) care on the outcome of prehospital patients, we monitored the influence of lack of sophisticated prehospital treatment in cases of severe illness arriving by ambulance to the emergency department (ED). A prospective cohort study to examine and compare the outcome of trauma- and nontrauma-induced "ALS-eligible" cases in the setting of no prehospital care was carried out from August 1, 1993 through May 31, 1994. On arriving at the ED, patients meeting the criteria for ALS cases and sent by EMS public prehospital personnel were assessed for subjective and objective status and change in severity by triage nurses as well as being followed up for neurological status until discharged from the hospital. Chi-Square method was used to compare the data between two groups and P < .05 was considered statistically significant. Of 667 studied ALS cases (155 trauma and 512 nontrauma), < 20% had their condition change subjectively and < 10% had their condition change objectively; 68% of medical patients and 60% of trauma cases were discharged from the hospital (neurologically intact). However, subgroup analysis showed that objective measures worsened in transit in nearly 18% of trauma victims, a rate nearly 3 times greater than that of medical cases. Moreover, neurological outcome was particularly poor in trauma cases. These results suggest that ALS care may be valuable for severely ill trauma victims.

EMS characteristics in an Asian Metropolis

A prospective citywide cohort study was conducted from August 1, 1993, through May 31, 1994 to analyze the epidemiological characteristics of emergency medical services (EMS) in an Asian city. Of 5,459 studied cases, the leading 3 causes were trauma (49.7%), alcohol intoxication (8.6%), and altered mental status (AMS) (6.9%). Half of the studied cases needed no prehospital care and 16.4% needed advanced life support (ALS) care. Traffic accidents accounted for 68% of trauma cases. Of 897 cases requiring ALS care, the two most common causes were AMS and dead on arrival (DOA) (32.1% and 21.2% in medical group, 10.1% and 4.5% in trauma group, respectively). The response time, time on scene, and transportation time were 4.6, 4.3, and 9.4 minutes, respectively. This Oriental EMS system experienced very short prehospital times, many traffic accidents, and extremely few DOA cases. Because few patients required ALS care, an emergency medical technician-based EMS system would probably be able to handle the majority of prehospital patients.