Virucidal activity of a plant-oil-based oral rinse against respiratory viruses

BACKGROUND

Respiratory viruses have been reported to infect the salivary glands and the throat, which are potential reservoirs for virus replication and transmission. Therefore, strategies to reduce the amount of infective virus particles in the oral mucous membranes could lower the risk of transmission.

METHODS

The viral inactivation capacity of a plant-oil-based oral rinse (Salviathymol®) was evaluated in comparison with chlorhexidine (Chlorhexamed® FORTE) using a quantitative suspension test according to EN 14476.

FINDINGS

Salviathymol efficiently inactivated severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), respiratory syncytial virus (RSV) and two influenza strains to undetectable levels.

CONCLUSION

Salviathymol has potential as preventive measure to lower transmission of respiratory viruses.

Evaluation of temperature, drying time and other determinants for the recovery of Gram-negative bacterial pathogens in disinfectant efficacy testing

BACKGROUND

In the clinical setting, surface disinfection is an important measure to reduce the risk of cross transmission of micro-organisms and the risk of nosocomial infections. Standardized methods can be used to evaluate disinfection procedures, as well as the effectiveness of the active ingredients used for disinfection. However, despite standardization, the results of such methodologies are still determined by several factors, and incorrect results may lead to invalid assumptions about the effectiveness of a disinfectant, posing significant health risks for patients and health personnel.

AIM

The objective of this study was to evaluate several determinants for the recovery of Pseudomonas aeruginosa and other test organisms to establish their influence on the results of standardized disinfection methodologies, and to find Gram-negative strains that can be used as suitable replacements for P. aeruginosa.

METHODS

The effects of inoculum application method, drying time, temperature and carrier material on the survival and recovery of the test organisms were evaluated using Student's t-test, one-way analysis of variance and Tukey's multiple comparison test.

FINDINGS AND CONCLUSIONS

Temperature, drying time, application method and carrier material were found to affect the recovery of P. aeruginosa cells significantly, and therefore influence the outcome of the methodologies used. This study also showed thatP. aeruginosa could be replaced with the Gram-negative species Acinetobacter baumannii, a test organism used in many standardized methodologies, which responds better under the same circumstances and has a behaviour similar to that of P. aeruginosa in disinfectant efficacy tests.

Virucidal activity of oral, hand, and surface disinfectants against respiratory syncytial virus

BACKGROUND

Respiratory syncytial virus (RSV) is known as a major cause of respiratory tract infection in adults and children. Human-to-human transmission occurs via droplets as well as direct and indirect contact (e.g. contaminated surfaces or hands of medical staff). Therefore, applicable hygiene measures and knowledge about viral inactivation are of utmost importance.

AIM

To elucidate the disinfection profile of RSV.

METHODS

The study evaluated the virucidal efficacy of oral rinses specifically designed for children, World Health Organization (WHO)-recommended hand-rub formulations, and ethanol, as well as 2-propanol against RSV in a quantitative suspension test (EN14476). The stability of RSV on stainless steel discs was assessed and its inactivation by different surface disinfectants (EN16777) investigated.

FINDINGS

All tested oral rinses except one reduced infectious viral titres to the lower limit of quantification. The two WHO-recommended hand-rub formulations as well as 30% ethanol and 2-propanol completely abolished the detection of infectious virus. Infectious RSV was recovered after several days on stainless steel discs. However, RSV was efficiently inactivated by all tested surface disinfectants based on alcohol, aldehyde, or hydrogen peroxide.

CONCLUSION

Oral rinses, all tested hand-rub formulations as well as surface inactivation reagents were sufficient for RSV inactivation in vitro.

Human cytomegalovirus seropositivity is associated with reduced patient survival during sepsis

BACKGROUND

Sepsis is one of the leading causes of death. Treatment attempts targeting the immune response regularly fail in clinical trials. As HCMV latency can modulate the immune response and changes the immune cell composition, we hypothesized that HCMV serostatus affects mortality in sepsis patients.

METHODS

We determined the HCMV serostatus (i.e., latency) of 410 prospectively enrolled patients of the multicenter SepsisDataNet.NRW study. Patients were recruited according to the SEPSIS-3 criteria and clinical data were recorded in an observational approach. We quantified 13 cytokines at Days 1, 4, and 8 after enrollment. Proteomics data were analyzed from the plasma samples of 171 patients.

RESULTS

The 30-day mortality was higher in HCMV-seropositive patients than in seronegative sepsis patients (38% vs. 25%, respectively; p = 0.008; HR, 1.656; 95% CI 1.135-2.417). This effect was observed independent of age (p = 0.010; HR, 1.673; 95% CI 1.131-2.477). The predictive value on the outcome of the increased concentrations of IL-6 was present only in the seropositive cohort (30-day mortality, 63% vs. 24%; HR 3.250; 95% CI 2.075-5.090; p < 0.001) with no significant differences in serum concentrations of IL-6 between the two groups. Procalcitonin and IL-10 exhibited the same behavior and were predictive of the outcome only in HCMV-seropositive patients.

CONCLUSION

We suggest that the predictive value of inflammation-associated biomarkers should be re-evaluated with regard to the HCMV serostatus. Targeting HCMV latency might open a new approach to selecting suitable patients for individualized treatment in sepsis.

Survival and inactivation of hepatitis E virus on inanimate surfaces

BACKGROUND

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis, and mainly transmitted via faecal-oral contamination or consumption of contaminated food products. However, limited data on the surface stability and HEV sensitivity to chemical disinfectants are available.

AIM

To establish an HEV-based carrier assay to evaluate its surface stability and the virucidal activity of nine surface disinfectants.

METHODS

A recently developed robust HEV-3 cell culture system for an HEV-based carrier assay.

FINDINGS

Alcohol-based disinfectants were insufficient to eliminate HEV infectivity, whereas disinfectants based on aldehyde, peracetic acid, oxygen, and/or quaternary ammonium inactivated HEV.

CONCLUSION

These findings have strong implications for the recommendation of evidence-based hygiene guidelines to reduce HEV transmission.

AB1452 EVALUATION OF HEPATITIS E VIRUS INFECTION DURING JAK INHIBITOR THERAPY IN AUTOIMMUNE INFLAMMATORY RHEUMATIC DISEASES

Background

Although impacting hundreds of thousands of people in Western nations each year, hepatitis E virus (HEV) is an under-reported health problem (1). HEV usually is a self-limiting disease, but especially immunocompromised individuals are at risk to develop a chronic course of infection, with rapid progression to fibrosis, cirrhosis or even the development of liver failure. Janus kinase (JAK) inhibitors are a novel drug class for the treatment of autoimmune inflammatory rheumatic disease (AIRD). As JAKs play a key role in innate immunity, viral infections and reactivation are frequently reported during JAK inhibitor treatment in AIRD patients (2).

Objectives

To characterize the influence of JAK inhibitors on HEV replication ex vivo and assess the risk for the development of symptomatic HEV infection during JAK Inhibitor therapy in vivo.

Methods

To determine the effect of JAK inhibitors on HEV replication we performed infection experiments with primary human hepatocytes (PHH) followed by immunofluorescence analysis and RNAseq. To evaluate the risk of HEV infection during JAK Inhibitor therapy, we monitored HEV RNA and HEV IgG/IgM of 111 AIRD patients, receiving JAK inhibitors. Moreover, we conducted a retrospective analysis of liver enzymes of patients which were anti-HEV IgG/IgM positive.

Results

Transcriptomic analysis of PHH revealed an upregulation of innate immunity components during HEV infection. This induction was perturbed in the presence of a JAK inhibitor, concomitant with strong elevation of HEV RNA levels. In line, infection experiments displayed an up to 50-fold increase of progeny virus production during JAK inhibitor treatment indicating that JAK signaling is critical to control HEV infection. Monitoring of seroprevalence identified 17 patients which were anti-HEV IgG and/or IgM positive, while no patient hat detectable HEV RNA levels. Five patients had detectable anti-HEV IgM levels suggesting a recent HEV infection. Three of 17 had a period with elevated liver enzymes (f.e. GGT> 200 U/L) during time of retrospective analysis (ranging from 10 to 23 months).

Conclusion

Obtained ex vivo data suggest that JAK inhibition facilitates HEV life cycle progression. Considering that JAK inhibitors are routinely applied for the treatment of AIRD, these patients may be at higher risk for a symptomatic course and outcome of HEV infection. In addition to established protocols, screening for HEV seroprevalence and HEV RNA should be considered prior starting JAK inhibitor treatment and in case of elevated liver enzymes during JAK inhibitor therapy.

References

[1]Faber M., Willrich N., Schemmerer M., Rauh C., Kuhnert R., Stark K., Wenzel J.J. Hepatitis E virus seroprevalence, seroincidence and seroreversion in the German adult population. J. Viral Hepat. 2018;25:752–758.

[2]Winthrop KL. The emerging safety profile of JAK inhibitors in rheumatic disease. Nat Rev Rheumatol. 2017;13:234–243.

Disclosure of Interests

None declared

Virucidal efficacy of an ozone-generating system for automated room disinfection

Besides conventional prevention measures, no-touch technologies based on gaseous systems have been introduced in hospital hygiene for room disinfection. The whole-room disinfectant device Sterisafe Pro, which creates ozone as a biocidal agent, was tested for its virucidal efficacy based on Association Française de Normalisation Standard NF T 72-281:2014. All test virus titres were reduced after 150 and 300 min of decontamination, with mean reduction factors ranging from 2.63 (murine norovirus) to 3.94 (simian virus 40). These results will help to establish realistic conditions for virus inactivation, and assessment of the efficacy of ozone technology against non-enveloped and enveloped viruses.

Virucidal efficacy of different formulations for hand and surface disinfection targeting SARS CoV-2

In the ongoing SARS CoV-2 pandemic, effective disinfection measures are needed, and guidance based on the methodological framework of the European Committee for Standardization (CEN) may enable the choice of effective disinfectants on an immediate basis. This study aimed to elucidate whether disinfectants claiming ‘virucidal activity against enveloped viruses’ as specified in the European Standard EN 14476 as well as in the German Association for the Control of Viral Diseases/Robert Koch Institute (DVV/RKI) guideline are effectively inactivating SARS-CoV-2. Two commercially available formulations for surface disinfection and one formulation for hand disinfection were studied regarding their virucidal activity. Based on the data of this study the enveloped SARS-CoV-2 is at least equally susceptible compared to the standard test virus vaccinia used in the EN 14476 and DVV/RKI guidelines. Thus, chemical disinfectants claiming ‘virucidal activity against enveloped viruses’ based on the EN 14476 and DVV/RKI guidelines will be an effective choice to target enveloped SARS-CoV-2 as a preventive measure.

Potential sources, modes of transmission and effectiveness of prevention measures against SARS-CoV-2

During the current SARS-CoV-2 pandemic new studies are emerging daily providing novel information about sources, transmission risks and possible prevention measures. In this review, we aimed to comprehensively summarize the current evidence on possible sources for SARS-CoV-2, including evaluation of transmission risks and effectiveness of applied prevention measures. Next to symptomatic patients, asymptomatic or pre-symptomatic carriers are a possible source with respiratory secretions as the most likely cause for viral transmission. Air and inanimate surfaces may be sources; however, viral RNA has been inconsistently detected. Similarly, even though SARS-CoV-2 RNA has been detected on or in personal protective equipment (PPE), blood, urine, eyes, the gastrointestinal tract and pets, these sources are currently thought to play a negligible role for transmission. Finally, various prevention measures such as handwashing, hand disinfection, face masks, gloves, surface disinfection or physical distancing for the healthcare setting and in public are analysed for their expected protective effect.

Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents

Currently, the emergence of a novel human coronavirus, SARS-CoV-2, has become a global health concern causing severe respiratory tract infections in humans. Human-to-human transmissions have been described with incubation times between 2-10 days, facilitating its spread via droplets, contaminated hands or surfaces. We therefore reviewed the literature on all available information about the persistence of human and veterinary coronaviruses on inanimate surfaces as well as inactivation strategies with biocidal agents used for chemical disinfection, e.g. in healthcare facilities. The analysis of 22 studies reveals that human coronaviruses such as Severe Acute Respiratory Syndrome (SARS) coronavirus, Middle East Respiratory Syndrome (MERS) coronavirus or endemic human coronaviruses (HCoV) can persist on inanimate surfaces like metal, glass or plastic for up to 9 days, but can be efficiently inactivated by surface disinfection procedures with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute. Other biocidal agents such as 0.05-0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate are less effective. As no specific therapies are available for SARS-CoV-2, early containment and prevention of further spread will be crucial to stop the ongoing outbreak and to control this novel infectious thread.

Prevalence and characterization of azole-resistant Aspergillus fumigatus in patients with cystic fibrosis: a prospective multicentre study in Germany

Objectives

Aspergillus fumigatus is the most prevalent filamentous fungus in the respiratory tract of patients with cystic fibrosis (CF). The aim of this prospective multicentre study was to investigate the prevalence of azole-resistant A. fumigatus (ARAF) in respiratory secretions from CF patients across Germany and to characterize ARAF isolates by phenotypic and molecular methods.

Methods

Twelve tertiary care centres from Germany participated in the study. In total, 2888 A. fumigatus isolates from 961 CF patients were screened for ARAF by using azole-containing agar plates. Antifungal susceptibility testing of isolates was performed by broth microdilution according to EUCAST guidelines. Analysis of mutations mediating resistance was performed using PCR and sequencing of the cyp51A gene. Furthermore, genotyping by microsatellite PCR was performed.

Results

Of a total of 2888 A. fumigatus isolates, 101 isolates from 51 CF patients were found to be azole resistant (prevalence per patient 5.3%). The Essen centre had the highest prevalence (9.1%) followed by Munich (7.8%), Münster (6.0%) and Hannover (5.2%). Most ARAF isolates (n = 89) carried the TR34/L98H mutation followed by eight G54E/R, one TR46/Y121F/T289A and one F219S mutation. In two isolates no mutation was found. Genotyping results showed no major clustering. Forty-five percent of CF patients with ARAF had previously received azole therapy.

Conclusions

This is the first multicentre study analysing the prevalence of ARAF isolates in German CF patients. Because of a resistance rate of up to 9%, susceptibility testing of A. fumigatus isolates from CF patients receiving antifungal treatment should be part of standard diagnostic work-up.

In-vitro activity of active ingredients of disinfectants against drug-resistant fungi

The biocidal activities of peracetic acid and ethanol were tested against nine clinical fungal isolates and four reference strains. Ethanol was active (≥4.0 log₁₀ reduction) against yeasts at a concentration of 50% v/v and against moulds at 80% v/v. Exposure times in both cases were 1 min. Peracetic acid was active as a 0.25% solution against yeasts and as a 0.5% solution against moulds; exposure times in both cases were 5 min. Compared with the reference strains, clinical isolates, including multi-drug-resistant strains, showed similar or higher sensitivity to the active ingredients of disinfectants in vitro.

Emergence of linezolid- and vancomycin-resistant Enterococcus faecium in a department for hematologic stem cell transplantation

Background

Prevalence of vancomycin-resistant enterococci has increased in Germany. Here, we report the cluster of linezolid- and vancomycin-resistant Enterococcus faecium (LVRE) in a German department for hematologic stem cell transplantation (HSCT).

Methods

In this retrospective analysis we included all patients with LVRE in a university-based department for HSCT in 2014 and 2015. Patients chart reviews were used to investigate the epidemiology and clinical outcome. Available LVRE isolates underwent detailed microbiological characterization and genotyping by pulsed-field gel electrophoresis (PFGE).

Results

In total, 20 patients with LVRE were identified within the observed time period. All except two patients underwent allogeneic HSCT. Surveillance culture results from incoming patients and chart review revealed that 10 of 20 patients were colonized at hospital admission. Eight of 10 patients with in-hospital acquired LVRE had previous linezolid treatment. Analysis of spatio-temporal patterns showed no evidence for LVRE patient-to-patient or environment-to-patient transmission within the HSCT department. In five cases (25 %) LVRE bloodstream infection occurred. Nine LVRE isolates could be saved for characterization. Eight isolates carried vanA, one isolate vanB. PFGE analysis showed that four different LVRE clones were responsible for the cluster. One single genotype was present in six LVRE isolates whereupon the corresponding patients were all referred from the same hospital to the HSCT department.

Conclusions

This is the first report demonstrating the emergence of LVRE in a German HSCT department. (L)VRE screening at patients’ admission and appropriate infection control strategies were sufficient to prevent any transmission. Further studies in this predisposed patient collective are warranted.

Extra-hepatic replication and infection of hepatitis E virus in neuronal-derived cells

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and a member of the genus Orthohepevirus in the family Hepeviridae. Infection usually leads to acute hepatitis that can become fulminant, particularly among pregnant women and in patients with preexisting liver disease, or may evolve to a chronic state, especially in immunosuppressed individuals. HEV has been shown to produce a range of extra-hepatic manifestations including aplastic anaemia, acute thyroiditis, glomerulonephritis as well as neurological disorders such as Guillain-Barré syndrome, neuralgic amyotrophy and encephalitis. The pathogenesis of these neurological injuries remains largely unknown, and it is also uncertain whether or not HEV can directly infect neuronal cells. In this study, we investigated whether HEV is capable of completing the viral life cycle in human neuronal-derived cell lines such as neuroepithelioma (SK-N-MC), desmoplastic cerebellar medulloblastoma (DAOY), glioblastoma multiforme (DBTRG), glioblastoma astrocytoma (U-373 MG) and oligodendrocytic (M03.13) cells. Following transfection of these cells with HEV Gaussia luciferase reporter virus, all tested cell lines supported HEV RNA replication. Furthermore, extra- and intracellular viral capsid was detected by an HEV antigen ELISA as a marker for virus assembly and release. Permissiveness for HEV cell entry could be demonstrated for the oligodendrocytic cell line M03.13. In conclusion, these results indicate that HEV tropism is not restricted to the liver and HEV can potentially complete the full viral life cycle in neuronal-derived tissues explaining neurologic disorders during HEV infection.

Anti-infective properties of epigallocatechin-3-gallate (EGCG), a component of green tea

The consumption of green tea (Camellia sinensis) has been shown to have many physiological and pharmacological health benefits. In the past two decades several studies have reported that epigallocatechin-3-gallate (EGCG), the main constituent of green tea, has anti-infective properties. Antiviral activities of EGCG with different modes of action have been demonstrated on diverse families of viruses, such as Retroviridae, Orthomyxoviridae and Flaviviridae and include important human pathogens like human immunodeficiency virus, influenza A virus and the hepatitis C virus. Furthermore, the molecule interferes with the replication cycle of DNA viruses like hepatitis B virus, herpes simplex virus and adenovirus. Most of these studies demonstrated antiviral properties within physiological concentrations of EGCG in vitro. In contrast, the minimum inhibitory concentrations against bacteria were 10-100-fold higher. Nevertheless, the antibacterial effects of EGCG alone and in combination with different antibiotics have been intensively analysed against a number of bacteria including multidrug-resistant strains such as methicillin-resistant Staphylococcus aureus or Stenotrophomonas maltophilia. Furthermore, the catechin EGCG has antifungal activity against human-pathogenic yeasts like Candida albicans. Although the mechanistic effects of EGCG are not fully understood, there are results indicating that EGCG binds to lipid membranes and affects the folic acid metabolism of bacteria and fungi by inhibiting the cytoplasmic enzyme dihydrofolate reductase. This review summarizes the current knowledge and future perspectives on the antibacterial, antifungal and antiviral effects of the green tea constituent EGCG.

Thermostability of seven hepatitis C virus genotypes in vitro and in vivo

Hepatitis C virus (HCV) is transmitted primarily through percutaneous exposure to contaminated blood especially in healthcare settings and among people who inject drugs. The environmental stability of HCV has been extrapolated from studies with the bovine viral diarrhoea virus or was so far only addressed with HCV genotype 2a viruses. The aim of this study was to compare the environmental and thermostability of all so far known seven HCV genotypes in vitro and in vivo. Incubation experiments at room temperature revealed that all HCV genotypes showed similar environmental stabilities in suspension with viral infectivity detectable for up to 28 days. The risk of HCV infection may not accurately be reflected by determination of HCV RNA levels. However, viral stability and transmission risks assessed from in vitro experiments correlated with viral infectivity in transgenic mice containing human liver xenografts. A reduced viral stability for up to 2 days was observed at 37 °C with comparable decays for all HCV genotypes confirmed by thermodynamic analysis. These results demonstrate that different HCV genotypes possess comparable stability in the environment and that noninfectious particles after incubation in vitro do not cause infection in an HCV in vivo model. These findings are important for estimation of HCV cross-transmission in the environment and indicate that different HCV genotypes do not display an altered stability or resistance at certain temperatures.

Outbreak due to a Klebsiella pneumoniae strain harbouring KPC-2 and VIM-1 in a German university hospital, July 2010 to January 2011

We describe the epidemiology and characteristics of the pathogen and patients (n=7) associated with an outbreak of a carbapenem-resistant Klebsiella pneumoniae (CRKP) strain in a German university hospital from July 2010 to January 2011. Species identification and detection of carbapenem resistance were carried out using standard microbiological procedures. Carbapenemases were detected by phenotypic methods and specific polymerase chain reactions (PCRs). DNA fingerprinting profiles were performed with repetitive sequence-based PCR. Medical records of colonised or infected patients were retrospectively reviewed. Antibiotic resistance profiles, PCR-specific amplification products and genotyping demonstrated that the outbreak occurred because of the spread of a single CRKP clone harbouring both KPC-2 and VIM-1. Five of the seven patients had invasive infections with the CRKP strain; the deaths of four of them were directly related to the infection. Early implementation of infection control interventions brought about efficient containment of further cross-transmission. Rapid dissemination of carbapenemase-producing Enterobacteriaceae is a serious concern in patient care and is a problem that has emerged in western Europe.

Outbreak due to a Klebsiella pneumoniae strain harbouring KPC-2 and VIM-1 in a German university hospital, July 2010 to January 2011

We describe the epidemiology and characteristics of the pathogen and patients (n=7) associated with an outbreak of a carbapenem-resistant Klebsiella pneumoniae (CRKP) strain in a German university hospital from July 2010 to January 2011. Species identification and detection of carbapenem resistance were carried out using standard microbiological procedures. Carbapenemases were detected by phenotypic methods and specific polymerase chain reactions (PCRs). DNA fingerprinting profiles were performed with repetitive sequence-based PCR. Medical records of colonised or infected patients were retrospectively reviewed. Antibiotic resistance profiles, PCR-specific amplification products and genotyping demonstrated that the outbreak occurred because of the spread of a single CRKP clone harbouring both KPC-2 and VIM-1. Five of the seven patients had invasive infections with the CRKP strain; the deaths of four of them were directly related to the infection. Early implementation of infection control interventions brought about efficient containment of further cross-transmission. Rapid dissemination of carbapenemase-producing Enterobacteriaceae is a serious concern in patient care and is a problem that has emerged in western Europe.

Hepatitis C virus enters human peripheral neuroblastoma cells - evidence for extra-hepatic cells sustaining hepatitis C virus penetration

Patients with chronic hepatitis C virus (HCV) infection show an increased incidence of nervous system disorders such as chronic fatigue syndrome, depression and cognitive dysfunction. It is unclear whether this is because of HCV replication in the brain and in peripheral neuronal cells or to more indirect effects of HCV infection on the central or peripheral nervous system. The aim of this study was to investigate whether cells originating from these tissues are permissive for HCV cell entry, RNA replication and virus assembly. Among eight cell lines analysed, the human peripheral neuroblastoma cell line SKNMC expressed all HCV entry factors and was efficiently infected with HCV pseudoparticles (HCVpp) independent of the HCV genotype. All remaining cell types including human neuroblastoma and glioblastoma cell lines and microglial cells lacked expression of at least one host factor essential for HCV entry. When transfected with HCV luciferase reporter virus RNA, inoculated with HCV reporter viruses or challenged with high-titre cell culture-derived HCV, none of these cells supported detectable HCV RNA replication. Thus, in conclusion, this comprehensive screening did not reveal evidence directly strengthening the notion that HCV enters and replicates in the central nervous system. However, productive viral entry into the peripheral neuroblastoma cell line SKNMC indicates that HCV may penetrate into certain nonhepatic cell types which may serve as viral reservoirs and could modulate viral pathogenesis.

Opponent colour coding is a universal strategy to evaluate the photoreceptor inputs in Hymenoptera

Behavioural tests were carried out with 9 hymenopteran insect species, which ranked certain sets of coloured stimuli according to their subjective similarity to a previously memorized stimulus. Kendall's tau co-efficient is employed for the analysis of correlation between these similarity rankings and the colour distance rankings predicted by various models of neural colour computation. The models are based on the measured spectral sensitivities of photoreceptor colour types and use a variety of simple colour coding systems to derive hypothetical colour distances. The correlation between the predictions of the models and the behavioural results serves as a measure for the likelihood of existence of a colour coding system. In all species, the similarity rankings can be best explained by assuming that colour is coded on a perceptual level by two colour opponent mechanisms. Brightness differences are ignored, indicating that an intensity-coding sub-system is not used in colour discrimination by the insects investigated. The weighting factors of the colour opponent mechanisms differ between species in detail, but not in the principles involved. It is thus possible to employ a standard measure of perceptual colour distance (colour hexagon distance) to predict the capacities of colour discrimination adequately in all the tested insects.

[Etiology of diarrheal diseases in immunocompetent and HIV-positive patients]

In 1986 and 1987 the stool samples of 206 patients of the Medical Outpatient Clinic Basel were examined prospectively for bacteria, protozoa and worms. Clinical data of the patients were recorded by questionnaire. The patient group comprised 63 immunocompetent patients as well as 23 HIV-infected patients, all with symptoms of acute enteritis. The control group consisted of 120 healthy persons. Pathogenic organisms were found in the stools of 17.5% of the immunocompetent patients with enteritis. The most common germs were Campylobacter jejuni, Giardia lamblia and Salmonella enteritidis. Isospora belli, found in 2 cases (8.7%), was the only pathogen found in HIV-infected patients. The most frequent pathogen found in 7.5% of the control group was Giardia lamblia. The facultative pathogenic protozoon Blastocystis hominis was found in 16.7-19.0% of the 3 groups. There was no correlation between clinical symptoms and the results of stool examinations. Stool examinations in the immunocompetent patients corresponded to the known distribution of pathogenic germs in Switzerland. The homogeneous distribution of Blastocystis hominis in the 3 groups examined proves the high rate of infection. There is no evidence of a significant correlation between clinical symptoms of enteritis and infection with Blastocystis hominis in immunocompetent patients.

[Prognostic significance of the T4 lymphocyte count in patients infected with CDC Class II and III HIV]

From 1985 to 1987 101 patients infected with the human immunodeficiency virus (HIV) were seen at our outpatient clinic and prospectively analyzed in a cohort study. We evaluated the follow-up in 41 patients of CDC classes II and III with regard to the number of T-helper lymphocytes (T4) and clinical progression. The patients consisted of 24 i.v. drug addicts, 11 homosexuals and 6 persons with other or multiple risk factors for HIV infection. Patients with a T4 count of less than 400/mm3 at the first visit did not differ significantly with regard to development of AIDS from those with a count of greater than 400/mm3 after a mean follow-up of approximately 1 year. The course of the infection for the individual patient was extremely varied and not predictable by the T4 value. We conclude that the number of the T4-lymphocytes is of no help in assessment of prognosis in the individual patient of CDC classes II and III.

Effects of gallopamil, nifedipine, Ni2+, and La3+ in guinea pig atria after a sudden increase in extracellular Ca2+ concentration

In isolated left atria of guinea pigs, we investigated the effects of four different calcium antagonists on the adaptation of force of contraction, action potential duration (APD), and calcium (Ca) content to a sudden change in the extracellular Ca2+ concentration ([Ca2+]0) from 0.9 to 3.6 mM. Under control conditions (rate of stimulation, 1 Hz), force of contraction rapidly adapted to an increase in [Ca2+]0 from 0.9 to 3.6 mM, reaching a transient maximum within 5 min ("hypercontractility"). The accompanying prolongation in APD also had a biphasic time course, but only when [Ca2+]0 was increased within the 1st hour of an experiment. The Ca antagonists investigated were gallopamil (0.2 microM), nifedipine (75 nM), Ni2+ (0.5 mM), and La3+ (1 mM). The negative inotropic effect of La3+ was complicated by an increase in resting tension after prolonged exposure (greater than 30-60 min). With the exception of Ni2+, the Ca antagonists depressed the maximum and the steady-state force of contraction after the increase in [Ca2+]0. The biphasic nature of force adaptation was attenuated by gallopamil, Ni2+, and La3+, but not by nifedipine. Gallopamil and La3+ slowed the time course of adaptation. The Ca content of the tissue was determined with the 45Ca method. Gallopamil, nifedipine, and Ni2+ had no effect on the Ca content nor on the time course of Ca uptake after the increase in [Ca2+]0, but La3+ profoundly slowed the time course of Ca uptake. Although inhibition of the Ca current by Ca antagonists modifies the functional adaptation to elevated [Ca2+]0, the Ca antagonists with the exception of La3+, do not influence the change in total Ca content. It is concluded that calcium channels are not the only pathway by which calcium is taken up by the tissue when [Ca2+]0 is increased.

[Importance of ECG and chest x-ray of ambulant patients with chest pain]

107 consecutive outpatients were examined prospectively to evaluate the contribution of clinical history, ECG and chest X-ray to diagnosis of chest pain. Based on patient history, clinical examination, ECG and chest X-ray, 23 (21.5%) of all patients had chest pain related to organic disease, whereas in 84 (78.5%) patients the symptomatology was of a functional/psychosomatic nature. In chest pain of organic origin ECG and chest X-ray contributed to diagnosis in 1/4 of the cases. In patients with so-called functional chest pain, ECG and chest X-ray were of no diagnostic value but had a psychological and therapeutic effect in a way that facilitated patient management.

Acute hemodynamic effects of bisoprolol, a new beta 1 selective adrenoreceptor blocking agent, in patients with coronary artery disease

To assess acute hemodynamic effects of the new beta-adrenergic blocking drug bisoprolol with experimentally documented beta 1 selectivity, we studied 16 patients with stable angina and angiographically proven coronary artery disease. Simultaneous right heart catheterization and radionuclide angiocardiography were performed at rest and during exercise without treatment (control) and 2 h after 5 mg bisoprolol (6 patients) and 20 mg bisoprolol (10 patients), respectively, administered perorally. The hemodynamic profile of bisoprolol was similar to that previously described after acute beta-blockade. A negative chronotropic effect occurred after 5 mg bisoprolol at rest, but the negative inotropic changes did not reach significance, whereas cardiac index decreased and total vascular resistance increased after 20 mg bisoprolol. During exercise, negative inotropic and blood-pressure-lowering effects were present after both dosages, resulting in improved myocardial oxygen consumption as reflected by a significantly reduced rate pressure product. Because ejection fraction and pulmonary capillary wedge pressure were not significantly changed even after the 20 mg dose, bisoprolol has only mild negative inotropic effects and seems hemodynamically safe.

Effects of bisoprolol in relation to metoprolol and bufuralol on left ventricular hemodynamics at rest and during exercise in chronic ischemic heart disease

To assess acute hemodynamic effects of bisoprolol on left ventricular hemodynamics at rest and during exercise, 16 patients with documented chronic ischemic heart disease were studied and compared with patients after administration of metoprolol and bufuralol. Simultaneous right heart catheterization and radionuclide angiocardiography were performed at rest and during exercise before and after drug administration. Bisoprolol was given orally to 16 patients, six receiving 5 mg, and 10 patients receiving 20 mg. Metoprolol was injected intravenously in a dose of 0.15 mg/kg to another 16 patients, and 30 mg bufuralol were given orally to 10 patients. The hemodynamic profiles of all three compounds were similar to that previously described after acute beta-blockade. All three drugs tested and compared showed a marked negative chronotropic effect, while there were slight differences in the negative inotropic and blood pressure lowering effect. Bisoprolol induced only mild negative inotropic changes, which were barely detectable after the 5 mg dose. The negative inotropic changes were more pronounced after metoprolol, and were partly balanced by the vasodilating properties of bufuralol. Thus, bisoprolol showed a significantly reduced rate pressure product with only a relatively mild negative inotropic effect. Based on these observations, even the higher dose of 20 mg bisoprolol seems to be hemodynamically safe for clinical application.

[Incidence and course of complex ventricular arrhythmias in myocardial infarct as a function of infarct size, heart function and persistent ischemia]

Incidence and course of complex ventricular ectopic activity (VEA) after myocardial infarction was prospectively evaluated in 217 patients in relation to infarct size, location, ventricular function and signs of persistent ischemia. Complex VEA (Lown greater than III) was found acutely in 138 patients (63.6%) and at hospital discharge in 42 (19.3%). Of 79 patients with VEA Lown less than or equal to III in the first 24 hours, 93.7% remained VEA-free at follow-up. Patients with persistent complex VEA differed from those who became VEA-free only in left and right ventricular ejection fraction, whereas all the other infarct related factors had no influence on the course of VEA.

[Inhibition and triggering of heart pacemakers by muscle potentials]

The unipolar pulse generator systems were tested in 220 patients (96 VVIM, 97 VVIO, 27 physiological systems) to determine the incidence of sensing interference with muscle potentials. 23% exhibited oversensing, with a sex distribution of 32% for males and 15% for females. The interference was observed more often in VVIM pacemakers at nominal setting (35%) than in VVIO pacemakers (11%). In DDD pacemakers both inhibition and triggering of ventricular stimulation was observed. Among the 23 patients with persisting syncope or dizziness after implantation of the pacemaker, the symptoms were observed during physical activity only in 5. In these 5 the underlying arrhythmia was tachycardia in 3 and inhibition of the pacemaker by muscle potentials in only one patient.

The morphologic diagnosis of analgesic (phenacetin) abuse

A number of different morphologic characteristics were examined to determine their relative values in establishing a purely morphologic diagnosis of phenacetin abuse. These included hyperpigmentation of the skin, the costal cartilages, the liver, and the renal tubules, and capillarosclerosis of the lower urinary tract. Hyperpigmentation of the skin, liver, and renal tubules cannot be used in the diagnosis of phenacetin abuse. Massive brown pigmentation of the costal cartilages in patients under 60 years of age suggests phenacetin abuse, but even this morphologic parameter, when used alone, is insufficient to establish a definite diagnosis. Capillarosclerosis in the lower urinary tract does, however, permit one to diagnose phenacetin abuse with certainty, as it is found exclusively in this condition.

[The value of dextran 70 in the prevention of thromboembolism in general surgery, orthopedics, urology and gynecology. A review of the literature]

28 prospective, controlled, randomised studies on the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) in surgical patients on dextran 70 prophylaxis are analysed. In all patients the diagnosis had been established by objective methods (fibrinogen test, phlebography, autopsy). In patients undergoing hip surgery (11 studies, mainly fractures of the upper end of the femur) the reduction in the number of DVT under dextran prophylaxis is the more evident the longer after operation phlebography is carried out. Coumarin and dextran prevention are equally effective. In 3 studies where diagnosis by the fibrinogen test was established during the first postoperative week only, no significant effect of dextran can be shown; there is no difference between the effect of dextran, coumarin or small doses of subcutaneous heparin. The effectiveness of dextran prophylaxis in reducing the DVT rate in general surgery (4 papers) is not clear, though 7 studies show that the number of fatal PE is reduced more than fivefold (p less than 0.0005). In patients on dextran prophylaxis, the incidence of DVT is equal to that in patients on coumarin prophylaxis before major gynecological surgery (4 papers). On postoperative initiation coumarin is significantly less effective than dextran. 2 further studies show that dextran is significantly effective as compared to controls and that there is no difference between dextran and heparin prophylaxis. Out of 1932 control patients 36 died of fatal PE verified at autopsy. Only 8 PE were seen in the group of 2011 patients receiving dextran prophylaxis (p less than 0.005). The effectiveness of dextran 70 corresponds to that of small doses of subcutaneous heparin. Dextran prevention is more effective in women than in men. Dextran prophylaxis is simple to carry out, has few contraindications, only rarely causes complications and is already effective during operation.