[Indications and preoperative planning for bariatric surgery]

These clinical practice guidelines represent the consensus opinion of a group of Austrian specialist physicians associated with the treatment of obesity. The recommendations incorporate the current literature and guidelines and aim to balance both procedural feasibility and patient acceptance and adherence. Special emphasis was placed on simplification of the preoperative clarification and maximum patient safety. Therefore, this article makes no claim to be complete in all fields.

[Overweight and obesity in adults: general principles of treatment and conservative management]

The prevalence of overweight and obesity is steadily increasing in Austria as well as internationally. Obesity in particular is associated with multiple health risks, comorbidities, functional disability, and social stigma. Obesity is an independent, complex, chronic disease and should be treated as such by a multidisciplinary team of appropriately qualified personnel. In addition to recent international guidelines, this consensus paper outlines the overall principles of the management of overweight and obesity and provides guidance for the diagnosis and conservative treatment, focusing on lifestyle modifications and pharmacotherapy. Using the "5A" framework of behavioral health intervention, guidelines for a structured, pragmatic, and patient-centered medical care of adults with overweight or obesity are presented.

[Diabetic neuropathy and diabetic foot syndrome (update 2023)]

These are the guidelines for diagnosis and treatment of diabetic neuropathy and diabetic foot.The position statement summarizes characteristic clinical symptoms and techniques for diagnostic assessment of diabetic neuropathy, including the complex situation of the diabetic foot syndrome. Recommendations for the therapeutic management of diabetic neuropathy, especially for the control of pain in sensorimotor neuropathy, are provided. The needs to prevent and treat diabetic foot syndrome are summarized.

Three-dimensional histology vs. serial section histology in the treatment of primary basal cell carcinoma: a randomized, prospective, blinded study of 569 tumours

BACKGROUND

For basal cell carcinoma (BCC), only few controlled data have been published so far, which directly compare micrographically controlled surgery with conventional serial section histology. In addition to Mohs surgery, which uses cryostat sections, also three-dimensional histology (3D-histology), based on paraffin sections, is available to ensure complete control of the margins and basic sections.

OBJECTIVES

To investigate the rate of local recurrence (LR) as well as the number of required re-excisions for basal cell carcinomas with serial section histology vs. 3D-histology.

METHODS

We compared serial sections histology with 3D-histology in a prospective, randomized, controlled blinded trial and analysed 569 BCC of all subtypes up to 30 mm diameter, 287 BCC in the 3D group and 282 BCC in the serial section group. Excisions were performed with adapted primary resection margin according to location and size of the tumour. Surgeons were blinded at the time of surgery as they did not know which histological method will be used. Both methods used paraffin sections.

RESULTS

Both groups did not differ regarding patients age, tumour location, tumour diameter, tumour subtypes or primary resection margins. In the serial section group, re-excisions were required in 21%; 24 tumours (8.4%) recurred after a median of 2.2 years. In the 3D-histology group, re-excisions were required in 39%; 10 tumours recurred (3.5%) after a median of 2.8 years. The recurrence rates differed significantly between both groups. Mean follow-up was 4.5 years.

CONCLUSIONS

3D-histology is a useful technique to detect tumour outgrowths at the excision margins, but required a high rate of re-excisions. 3D-histology was associated with a significantly lower LR rate than serial section histology.

Transmission of SARS-CoV-2 in children aged 0 to 19 years in childcare facilities and schools after their reopening in May 2020, Baden-Württemberg, Germany

We investigated data from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected 0–19 year olds, who attended schools/childcare facilities, to assess their role in SARS-CoV-2 transmission after these establishments’ reopening in May 2020 in Baden-Württemberg, Germany. Child-to-child transmission in schools/childcare facilities appeared very uncommon. We anticipate that, with face mask use and frequent ventilation of rooms, transmission rates in schools/childcare facilities would remain low in the next term, even if classes’ group sizes were increased.

Assessment of Public Health and Economic Impact of Intranasal Live-Attenuated Influenza Vaccination of Children in France Using a Dynamic Transmission Model

OBJECTIVES

We estimated the epidemiological and economic impact of extending the French influenza vaccination programme from at-risk/elderly (≥65 years) only to healthy children (2-17 years).

METHODS

A deterministic, age-structured, dynamic transmission model was used to simulate the transmission of influenza in the French population, using the current vaccination coverage with trivalent inactivated vaccine (TIV) in at-risk/elderly individuals (current strategy) or gradually extending the vaccination to healthy children (aged 2-17 years) with intranasal, quadrivalent live-attenuated influenza vaccine (QLAIV) from current uptake up to 50% (evaluated strategy). Epidemiological, medical resource use and cost data were taken from international literature and country-specific information. The model was calibrated to the observed numbers of influenza-like illness visits/year. The 10-year number of symptomatic cases of confirmed influenza and direct medical costs ('all-payer') were calculated for the 0-17- (direct and indirect effects) and ≥18-year-old (indirect effect). The incremental cost-effectiveness ratio (ICER) was calculated for the total population, using a 4% discount rate/year.

RESULTS

Assuming 2.3 million visits/year and 1960 deaths/year, the model calibration yielded an all-year average basic reproduction number (R ₀) of 1.27. In the population aged 0-17 years, QLAIV prevented 865,000 influenza cases/year (58.4%), preventing 10-year direct medical expenses of €374 million. In those aged ≥18 years with unchanged TIV coverage, 1.2 million cases/year were averted (27.6%) via indirect effects (additionally prevented expenses, €457 million). On average, 613 influenza-related deaths were averted annually overall. The ICER was €18,001/life-year gained. The evaluated strategy had a 98% probability of being cost-effective at a €31,000/life-year gained threshold.

CONCLUSIONS

The model demonstrated strong direct and indirect benefits of protecting healthy children against influenza with QLAIV on public health and economic outcomes in France.

Basal serum tryptase as risk assessment for severe Hymenoptera sting reactions in elderly

BACKGROUND

Epidemiologic studies suggest that elderly people are more prone to develop severe anaphylactic reactions. However, the exact cause for this phenomenon remains unclear.

AIMS OF THE STUDY

To study the role of the serum tryptase as a diagnostic parameter for individual risk evaluation and its impact on the severity of allergic reactions in elderly people.

METHODS

Two hundred and seventy-four consecutive patients visiting the Department of Dermatology, Tübingen, Germany, who were diagnosed with honeybee or wasp venom allergy, were included in the study.

RESULTS

Sting reaction severity increased with increased age and tryptase levels (P = 0.001 and P = 0.0003, respectively). Furthermore, we find not only a general increment in tryptase levels in elderly people (P = 0.0001) but also a continuous increase in tryptase concentrations even below the cut-off (11.4 microg/l) with increasing age (P = 0.0026).

CONCLUSIONS

Our data confirm serum tryptase as a risk factor for severe anaphylactic reaction to hymenoptera stings. Furthermore, we give first evidence that basal serum tryptase levels increase continuously with age and being an indicator for either increased mast cell load or reactivity this can at least partly be responsible for the observed aggravated allergic reactions in elderly people. As those patients are at increased risk for life-threatening anaphylactic reactions, it should be considered to adjust VIT especially in elderly patients with elevated tryptase levels as recommended for patients with mastocytosis by increasing venom doses during VIT and by considering its life-long continuation.

The impact of contact structure on infectious disease control: influenza and antiviral agents

Planning adequate public health responses against emerging infectious diseases requires predictive tools to evaluate the impact of candidate intervention strategies. With current interest in pandemic influenza very high, modelling approaches have suggested antiviral treatment combined with targeted prophylaxis as an effective first-line intervention against an emerging influenza pandemic. To investigate how the effectiveness of such interventions depends on contact structure, we simulate the effects in networks with variable degree distributions. The infection attack rate can increase if the number of contacts per person is heterogeneous, implying the existence of high-degree individuals who are potential super-spreaders. The effectiveness of a socially targeted intervention suffers from heterogeneous contact patterns and depends on whether infection is predominantly transmitted to close or casual contacts. Our findings imply that the various contact networks' degree distributions as well as the allocation of contagiousness between close and casual contacts should be examined to identify appropriate strategies of disease control measures.

Estimation of the duration of vaccine-induced residual protection against severe and fatal smallpox based on secondary vaccination failure

BACKGROUND

Understanding the loss of vaccine-induced immunity against smallpox is essential in determining the fraction of those who are still protected in the present population and in constructing effective countermeasures against bioterrorist attacks.

METHOD

Three small Australian outbreaks from the 1880s to early 1900s were investigated. Each documented individual age at infection. The case records for Launceston, 1903, further documented the age at vaccination and disease severity, enabling estimates of the duration of protection against severe and fatal smallpox.

RESULTS

A significant association between vaccination and death was observed in the outbreak in Sydney, 1881 (odds ratio of death among vaccinated individuals = 0.3; 95% confidence interval (CI): 0.1, 0.8; p = 0.02), where the time since last vaccination was similar for all vaccinated cases. In Launceston, 1903, where the age at vaccination varied widely, the median duration of partial protection against severe and fatal smallpox was estimated to be 31.7 (95% CI: 13.2, 116.2) and 53.9 (95% CI: 25.6, 123.5) years after vaccination, respectively. Whereas those in their 20s are expected to have the highest frequency of vulnerability to smallpox death in the present population, infections among those in their 30s or 40s are expected to be much less fatal.

CONCLUSION

Long lasting partial protection was suggested from the outbreak records, the estimated durations of which were roughly consistent with those reported previously. In the event of a bioterrorist attack, those involved in emergency tasks before emergency vaccination practices are re-established should ideally be previously vaccinated individuals in their 30s or 40s.

High infection rates at low transmission potentials in West African onchocerciasis

Onchocerciasis has been successfully controlled for many years in endemic countries but more than 120 million people are still at risk. Factors which stabilise the persistence of the parasite in the population must be studied to minimise the future risk of re-infection. Among these factors, the relationship between the annual transmission potential and the parasite establishment rate is a main determinant which has to date not been quantified. Using entomological information and palpation data collected by the Onchocerciasis Control Programme in West Africa prior to the initiation of control activities, we derive annual transmission potential-dependent estimates of the parasite establishment rate from statistical analyses and computer simulations. Even at very low transmission intensities, the filarial parasite Onchocerca volvulus can efficiently establish in the human population, originating from an infection process which is strongly limited with respect to the annual transmission potential. Implementing the estimates into a simplified transmission model predicts that the critical annual biting rate, below which transmission is not possible, is much lower than previously assumed. We conclude that under the current strategy of mass distribution of microfilaricides without additional measures of vector control, the risk of re-infection is higher than previously assumed.

Reinnervation-induced alterations in rat skeletal muscle

Denervation-induced myofiber atrophy can be reversed by reinnervation. Growing reinnervated myofibers upregulate numerous molecules, many of which determine the muscle fiber type. In the present study we aimed at identifying factors that might contribute specifically to myofiber growth after reinnervation. The common peroneal nerve of 15 male Wistar rats was cut and resutured without delay (9 animals) or with a delay of 4 weeks (6 animals). We studied the transcriptional repertoire of intact reinnervated tibialis anterior muscle by microarray gene analysis. We assessed SC activation by immunolabeling using anti-MyoD and -myogenin antibodies. The percentage of SC expressing MyoD reached up to 50% of M-cadherin+ cells whereas the percentage of SC expressing myogenin was normal (<10%) in all muscles examined. The values of ipsi- and contralateral muscles did not differ significantly from one another between right and left leg (p<0.05). Thirteen known genes were differentially regulated after reinnervation compared with contralateral muscles. Five of them determine the slow-twitch fiber type (four and a half LIM domains 3, cardiac beta-myosin heavy chain, calsequestrin 2, troponin C (slow), and heart myosin light chain), and three of them are neurally regulated (thrombospondin 4, transferrin receptor, cardiac ankyrin repeat protein). The results strengthen the notion that reinnervaton affects the molecular repertoire of the myofibers directly, leading to fiber type transformation and partial reversal of the denervation phenotype. By contrast, SC do not appear to be affected by reinnervation directly. They can be activated both in reinnervated and contralateral muscles, and they do not fully differentiate. This makes them unlikely to contribute to myofiber growth.

Lipopolysaccharide-binding protein in noninfected neonates and those with suspected early-onset bacterial infection

OBJECTIVES

To investigate postnatal lipopolysaccharide-binding protein (LBP) kinetics in term neonates and to test its diagnostic accuracy for early-onset bacterial infection (EOBI).

STUDY DESIGN

A total of 99 neonates with clinical and serological signs of EOBI comprised the study group; 198 neonates with risk factors, but without EOBI, served as controls. LBP, C-reactive protein (CRP) and interleukin-8 (IL-8) were determined.

RESULTS

LBP in the noninfected group increased until 24 h after birth (P < 0.05 vs 6 h). LBP and CRP correlated strongly in neonates with suspected EOBI (r = 0.63). Although LBP reached a higher sensitivity than CRP 6 and 12 h after clinical suspicion (45 (24-68) and 79% (54-94) vs 9 (0-24) and 39% (17-64); P < 0.05)), EOBI was most reliably detected by IL-8.

CONCLUSION

LBP kinetics were age-dependent. LBP was not sufficiently sensitive in the prediction of EOBI.

The influence of competition and vaccination on the coexistence of two pneumococcal serotypes

Streptococcus pneumoniae (pneumococcus) is one of the most important bacterial pathogens and a leading cause of mucosal infections (e.g. otitis media) and various forms of serious diseases (e.g. pneumonia, meningitis, bacteraemia) in developing and developed countries. Based on the polysaccharide capsule, there are at least 90 different pneumococcal serotypes, which may compete with each other to colonize the nasopharynx. Newly developed protein-polysaccharide conjugated vaccines have been shown to provide protection against disease caused by the serotypes included in the vaccine, and also against colonization (carriage). It is feared that yet uncommon, but nonetheless pathogenic serotypes which have been suppressed by competition, may become more prevalent in carriage and disease after large-scale use of conjugate vaccines. In this paper, we use transmission models of pneumococcal carriage to study how competition and vaccination influence the coexistence of two serotypes. According to our results, direct (physical) competition between two pneumococcal serotypes only influences colonization if the duration of naturally acquired immunity is short. By contrast, indirect (antibody-mediated) competition is of influence only if naturally acquired immunity is long lasting. Vaccination reduces the prevalence of the target serotype--an effect that is enforced by the presence of directly competing bacteria. The emergence of a non-target serotype after vaccination is only observed if bacteria compete directly. These results emphasize the importance of studying whether bacteria compete directly or indirectly and for how long people are protected in order to assess the long-term effects of sero-competition.

Modelling transmission, immunity and disease of Haemophilus influenzae type b in a structured population

An individual-based stochastic simulation model was constructed to study the epidemiology of Haemophilus influenzae type b (Hib) transmission, immunity and invasive disease. Embedded in a demographic model, the transmission model of Hib carriage employs the most important social mixing patterns with three types of contact sites (family, day-care group, and school class). The model includes immunity against invasive Hib disease, initiated and boosted by Hib carriage and cross-reactive bacterial encounters. The model reproduces the observed age patterns in Hib carriage and disease in Finland before large-scale use of the Hib conjugate vaccines. The model was used to investigate characteristics of Hib transmission. The analysis emphasizes transmission between children and adults in families while pointing out the importance of pre-school and school-aged children in maintaining Hib circulation. Carriage in these age groups is thus identified as being essential to target for sustained effects of interventions by vaccination.

The relationships between the burden of adult parasites, host age and the microfilarial density in human onchocerciasis

We investigate the relationship between the microfilarial density in the skin and the burden of adult female Onchocerca volvulus by analysing pre-control nodulectomy data which allow for a direct approach, independent of exposure. The data of 169 patients in Burkina Faso and 182 patients in Liberia represent savannah and forest onchocerciasis in West Africa, respectively. Whereas in Burkina Faso, a saturating relationship between microfilarial density and worm burden suggests the operation of density-dependent processes within human hosts, the Liberian data show a linear relationship implying no density dependence. The differences may derive from differences between both parasite strains, i.e. the savannah or the forest strain of O. volvulus. Consistently for both parasite strains and independent of the worm burden, the microfilarial density increases with host age emphasising the concept of the acquisition of immunological tolerance. In male hosts in Liberia, the microfilarial density increases stronger with the worm burden than in female hosts, whereas such sex-specific differences cannot be found in Burkina Faso. In the methodological part of this investigation, we suggest the beta-distribution to be most appropriate for describing variability in microfilarial densities and we present an approach to consider the uncertainty in the adult parasite burden which cannot be determined precisely in helminth infections. Implications of density dependence are discussed with respect to immunological processes in the human host and with respect to the success of control programs. The relationships described show that regulatory processes between the parasite and the human host are multi-dimensional, operating within a high degree of biological variability.

The influence of Emla cream on cutaneous microcirculation

Emla cream is frequently used in surgical dermatology and in anesthesiology, for instance, during vascular surgery procedures. Because local anesthetics can have a vasoactive effect in addition to producing analgesia, we decided to document the effect of 5% Emla cream on cutaneous circulation in a prospective, placebo-controlled study. Skin circulation was monitored continuously under standardized conditions using video capillaroscopy, laser Doppler flowmetry and skin temperature. Recordings were made at the nailfold of the fourth finger (DIV) of the left hand of 12 volunteers with healthy veins over an observation period of 60 minutes under either Emla occlusive dressing or an occlusive dressing with placebo. Mean capillary red blood cell velocity changed only minimally under the Emla occlusive dressing, while placebo occlusive dressing led to a reduction of mean capillary red blood cell velocity from 0.21 mm/s to 0.12 mm/s (p<0.01). There was no statistically significant change of arterial capillary diameter under Emla or placebo occlusive dressing. Skin temperature dropped after 60 minutes of Emla cream occlusive dressing from an initial 26.7 to 24.0 degrees C (-10.1%; p<0.02). The same duration of placebo caused skin temperature to drop from 27.6 to 23.0 degrees C (-16.7%; p<0.001). Laser Doppler flux (543 nm) rose 13% with Emla (p=0.9) and dropped 41.9% under placebo occlusive dressing (p<0.03). Emla cream upregulated nutritive perfusion. No clinically relevant vasoconstrictive effects are expected from an application period of 60 minutes.

Density-dependent parasite establishment suggests infection-associated immunosuppression as an important mechanism for parasite density regulation in onchocerciasis

The modulation of human immune response by filarial parasites has yielded contradictory experimental findings and attracted much controversy. We address the unresolved question of acquisition, establishment and accumulation of Onchocerca volvulus by using a modelling approach that relates computer simulations to cross-sectional data concerning parasite burdens in 913 West African onchocerciasis patients. It is shown that the acquisition of O. volvulus is not constant with host age; instead, the analysis of age profiles of parasite burdens strongly indicate the operation of immunosuppressive processes within the human host, associated with the presence of adult parasites or microfilariae. It is suggested that these processes suppress immunity against incoming infective larvae (L3), which themselves act as an immune modulating component once they have successfully overcome the barrier of concomitant immunity. Suppression of parasite-specific immunity leads to parasite establishment rates which increase along with the parasite burden, but which hardly depend on hyperendemic annual transmission potentials. Children, still immunocompetent due to low parasite burdens, acquire 0.1-0.5 adult female parasites per year, whereas older people, immunosuppressed due to high burdens, acquire 2-4 adult female parasites per year. Differences in parasite establishment between the forest and the savannah strains of O. volvulus are quantified and dynamic aspects of density-dependent parasite establishment discussed.

On the interpretation of age-intensity profiles and dispersion patterns in parasitological surveys

The present paper describes how age-intensity profiles of macroparasite burdens are affected by processes underlying the distribution of the parasite numbers in host populations. In a comparative way, we consider the following 6 processes: (i) age-dependent exposure, (ii) parasite-induced host mortality, (iii) heterogeneity within, the host population, (iv) clumped infection, (v) density-dependent parasite mortality and (vi) density-dependent parasite establishment. For each of these processes, we show typical patterns in the age-intensity profile and provide, if possible, explicit and simple solutions for the age-dependent mean parasite burden and the corresponding dispersion patterns. Emphasis is given to density-dependent parasite establishment and to age-intensity profiles resulting from the superposition of different processes. By means of 2 examples we show that the interpretation of observed patterns can be ambiguous if more than 1 process takes place. These findings underline that age-intensity profiles should be interpreted on the basis of available a priori knowledge about the processes assumed to be involved. For purposes of testing different hypotheses, a simulation program is provided with which discrepancies between model prediction and data can be explored.

Endothelial accumulation of hydroxyethyl starch and functional consequences on leukocyte-endothelial interactions

To date, accumulation of hydroxyethyl starch (HES) has been studied mainly in skin specimens, but there are no detailed reports available regarding starch accumulation in the endothelium. Because endothelial cells play an essential role during shock, we studied the accumulation of HES in human umbilical venous endothelial cells (HUVEC). HUVEC (n = 9) were incubated with a fluorescein-conjugated HES 200/0.5 (FITC-HES) at 0.5-20 mg/ml for 1-72 h. FITC-HES was internalized dose- and time-dependently by pinocytosis into secondary lysosomes. Asymptotic elimination curves showed that 50% of the formerly ingested molecules could not be eliminated. Despite accumulation, starch molecules did not attenuate the expression of E-selectin, ICAM-1 or VCAM-1 on TNF-alpha-activated HUVEC. However, apart from adhesion molecule expression, perfusion studies showed that HES reduced neutrophil adhesion by direct inhibition of integrin-mediated interactions.

Estimation of the time-dependent vaccine efficacy from a measles epidemic

We present a method to estimate the time-dependent vaccine efficacy from the cohort-specific vaccination coverage and from data on the vaccination status of cases and apply it to a measles epidemic in Germany which involved 529 cases, 88 of whom were vaccinated and 370 unvaccinated (for the remaining 71 cases the vaccination status is unknown). Our epidemiological model takes into account that maternal antibodies prevent successful vaccination and that vaccine immunity may be lost over time. Model parameters are estimated from the data using maximum likelihood. Vaccination coverage, as determined in school surveys, ranged from 27.6 per cent for the cohort born in 1974 to 85 per cent for the 1986 cohort, which is far too low to prevent measles transmission. Cohorts for which no school surveys were performed are omitted from analysis. Thus, sufficient data are available for only 282 cases, 69 of whom are vaccinated. According to our estimates, measles vaccinations provided no immunity before 1978 (95 per cent CI: 0 to 47 percent), for the period 1978-1982, the estimated vaccine efficacy was 80 percent (95 percent CI: 67 to 89 percent), and for 1982-1990 it was 97 percent (95 percent CI: 93 to 99 percent). After 1990, the estimated value dropped to 89 per cent, but its confidence interval widely overlaps with that of the previous period (95 percent CI: 74 to 97 percent). Loss of immunity was estimated to be zero (95 percent CI: 0 to 0.003/year). Several sensitivity analyses were performed with respect to the model assumptions. A modified model which assumed constant efficacy at all vaccination times yielded a high estimate of 96 per cent (95 percent CI: 92 to 98 percent) for primary vaccine efficacy but also a high loss rate of immunity of 0.007/year (95 percent CI: 0.001 to 0.012) to explain the high fraction of vaccinated cases among older individuals. The likelihood score value is however significantly inferior compared to the score value of the model with time-dependent vaccine efficacy.

Klinische Überprüfung des Anpressdrucks unterschiedlicher Konfektionsgrößen des zirkulären Kompressionsfertigverbands Tubulcus®

Ziel: Zur Kompressionstherapie, die bei der chronischen venösen Insuffizienz als phlebologisches Basistherapeutikum gilt, werden Serienprodukte für unterschiedliche Unterschenkelumfänge angeboten. Direkt am Patienten sollte geprüft werden, ob die unterschiedlichen Konfektionsgrößen entsprechend den verschiedenen Unterschenkelumfängen einen konstanten Anpressdruck ausüben. Material und Methoden: 50 Gefäßgesunde wurden in die Studie aufgenommen (25 Frauen, 25 Männer, Alter 26,7 Jahre, SD 13,4). Der Anpressdruck der 5 Konfektionsgrößen des zirkulären Kompressionsverband Tubulcus® wurde an je 10 Unterschenkeln bestimmt. Ergebnisse: Bei den getesteten Unterschenkelumfängen und passenden Konfektionsgrößen wurde der therapeutisch wünschenswerte Anpressdruck (40-50 mmHg) in liegender Körperposition gemessen. Die Variabilität des lokalen Anpressdrucks war im Bereich der Fessel bei der kleinsten Größe (S) und zunehmender Umfangsgröße (XL, etwas geringer XXL) am größten. Der hämodynamisch relevante Quotient aus Arbeits- und Ruhedruck war bei den unterschiedlichen Konfektionsgrößen vergleichbar mit dem von phlebologischen Kompressionsverbänden mit Kurzzugbinden. Schlussfolgerung: Die Verordnung unterschiedlicher Größen eines Kompressionsmittels orientiert sich am korrekt gemessenen Beinumfang und lässt dann eine gleichbleibende Druckwirkung erwarten. Dies konnte in der vorliegenden Studie für den zirkulären Kompressionsverband gezeigt werden.

Genesis, sequestration and survival of Plasmodium falciparum gametocytes: parameter estimates from fitting a model to malariatherapy data

Plasmodium falciparum malaria is one of mankind's main killers. Part of the parasite's life-cycle is spent in human blood, mainly as asexual stages. A fraction of the asexual parasites develops into gametocytes (gamete precursors) while sequestered in deep tissues. After re-entering the circulation, gametocytes can be picked up by a mosquito to continue the parasite's life-cycle. We present estimates of the conversion probability from asexual parasites to circulating gametocytes and of the gametocytes' sequestration and circulation times, obtained for the first time by fitting a dynamic model to individual patients' histories (daily records of 113 neurosyphilitic patients undergoing malariatherapy). The model assumes that the conversion probability can vary among the successive waves of asexual parasitaemia of a patient, and that gametocytes die at an age-dependent rate which increases under high asexual parasite densities. On average, 1 gametocyte per 156 asexual parasites (range 7.4-3700) is produced. The most remarkable findings are the large individual variation of conversion probabilities and circulation times, the average gametocyte circulation time of 6.4 days (range 1.3-22.2 days) which is more than twice the currently accepted value, and the large variation of conversion probabilities among successive waves of asexual parasitaemia without any particular time pattern. The latter finding could be explained by an association between conversion probability and variation of PfEMP1.

[Medical compression therapy]

In order to evaluate the correlation between the pressure exerted by compression stockings and a resulting improvement in venous hemodynamics, we carried out an open, randomized, prospective study on 22 patients (11 women and 11 men with an average age of 55.1 [10.3]) with chronic venous insufficiency (CVI) in the clinical stages C1-4, Ep, AS, Ap, PR. Dynamic strain gauge plethysmography was used to measure the acute effect on venous hemodynamics of 9 different compression stockings in compression class 2 (A-D). At the same time when venous function parameters were monitored, we also measured the pressure exerted by the compression stockings during rest and exercise. With all compression stockings the average resting pressure fulfilled in reclined patients the specifications for compression class 2 (25-35 mmHg at the ankle, CEN). The compression stockings lengthened venous refill time t0 in a statistically significant degree. The improvement in venous function was correlated with the ratios of maximal working pressure to resting pressure while standing (r = 0.97, p < 0.001). Compression stockings belonging to the same compression class vary in their acute effect on venous hemodynamics. The efficiency of the different therapeutic compression stockings was largely dependent on the amount of fabric stretch, which can be characterized in vivo with the ratio of maximum exerted pressure during movement to that while standing still. A knowledge of the hemodynamic effectivity of the various compression stockings allows the optimal stocking selection for each patient and his individual clinical situation.

Plasmodium falciparum parasitaemia described by a new mathematical model

A new mathematical model of Plasmodium falciparum asexual parasitaemia is formulated and fitted to 35 malaria therapy cases making a spontaneous recovery after primary inoculation. Observed and simulated case-histories are compared with respect to 9 descriptive statistics. The simulated courses of parasitaemia are more realistic than any previously published. The model uses a discrete time-step of 2 days. Its realistic behaviour was achieved by the following combination of features (i) intra-clonal antigenic variation, (ii) large variations of the variants' baseline growth rate, depending on both variant and case, (iii) innate autoregulation of the asexual parasite density, variable among cases, (iv) acquired variant-specific immunity and (v) acquired variant-transcending immunity, variable among cases. Aspects of the model's internal behaviour, concerning variant dynamics, as well as the respective contributions of the three control mechanisms (iii) - (v), are displayed. Some implications for pathogenesis and control are discussed.

[A new optoelectronic measuring device for assessment of leg circumference in comparison with manual measurement]

For compression treatment to be effective in patients with chronic venous insufficiency, it is vital that leg circumference be measured accurately. If compression stockings are custom fit and appropriate for the medical indications, patient compliance will be high. Exact measurements of circumference and length are prerequisites for a good fit. The aim of the present study was to compare an opto-electronic device for the contact-free measurement of calf circumference with the conventional manual method using a tape measure. We investigated the differences between the results obtained with the two methods, and also their reproducibility. Circumferences were measured at defined heights on an anatomically shaped non-yielding leg model and on the leg of a healthy volunteer by 10 different experimenters both with the tape measure and with the opto-electronic device. The calf circumferences measured manually with the tape measure varied significantly more than those measured opto-electronically, both in the leg model and in the leg of the volunteer. A systematic error in the opto-electronic method appears unlikely, since the manual measurements on the leg model were both larger and smaller than those obtained with the opto-electronic device. Reproducibility was exceptionally high with the opto-electronic device (standard deviation 0.11-0.42 cm). The opto-electronic method yields rapid accurate measurements of circumference with excellent intra- and inter-operator reproducibility.

Modelling the transition of asexual blood stages of Plasmodium falciparum to gametocytes

In this paper, we investigate the transition of asexual blood stages of P. falciparum to gametocytes. The study is based on daily data, collected from 262 individual courses of parasitaemia. We propose several mathematical models that follow biological reasoning. The models are fitted with maximum likelihood and are compared with each other. The models differ in the assumptions made about the mortality of circulating gametocytes and about the transition rate of the asexual parasites. Gametocyte mortality is modelled as being (i) constant over time, (ii) linearly increasing over time, (iii) linearly increasing over gametocyte age, and (iv) exponentially increasing over gametocyte age, respectively. The transition rate is either kept constant per patient or piecewise constant within intervals that correspond to waves of asexual parasitaemia which are assumed to be caused by different Pf(emp1)-variants. According to likelihood ratio tests, the models with age-dependent mortality rate and wave-dependent transition rates are superior to the models with constant transition rate and/or constant or time-dependent mortality rate. The best fits are reached for models with exponentially increasing (Gompertz-type) mortality. Furthermore, an impact of high asexual parasite densities on the survival of gametocytes, interpreted as a cytokine-mediated effect, is evident in some cases.

Certain batches of albumin solutions influence the expression of endothelial cell adhesion molecules

OBJECTIVE

Increased levels of soluble adhesion molecules, a decreased PO2/FIO2 ratio and a tendency to worsened outcome have been reported following the use of human albumin in critical illness. The reasons are not yet understood. Since albumin solutions have previously been shown to contain proinflammatory mediators, a direct upregulation of adhesion molecules by contaminated batches may explain these findings. To examine this, we studied the effects of different albumin preparations on endothelial cell adhesion molecules in vitro.

DESIGN

Experimental study.

SETTING

Laboratory for cell biology.

METHODS

Human umbilical venous endothelial cell cultures (n = 4) were incubated for 6 h at 5 mg/ml with four different human albumin solutions (HA1-4) from different manufacturers. Medium served as the control. Using flow cytometry, the effects on E-selectin, ICAM-1 and VCAM-1 expression were determined on unstimulated cells and on cells stimulated with tumour necrosis factor alpha at 0.5 ng/ml for 4 h.

MEASUREMENTS AND RESULTS

On unstimulated cells, HA1 and HA4, two different batches from the same manufacturer, increased ICAM-1 by 22% and 15%, respectively. After stimulation, both solutions resulted in a 19% increased expression of E-Selectin. In addition, HA4 decreased VCAM-1 on stimulated cells (p < or = 0.05). Two albumin preparations from other manufacturers did not produce significant effects.

CONCLUSIONS

Some albumin solutions directly modulate adhesion molecule expression on endothelial cells. This may, at least in part, explain the previous finding of increased soluble adhesion molecules and a decreased PO2/FIO2 ratio in critically ill patients undergoing volume replacement with human albumin.

A hierarchical Bayesian model to predict the duration of immunity to Haemophilus influenzae type b

A hierarchical Bayesian regression model is fitted to longitudinal data on Haemophilus influenzae type b (Hib) serum antibodies. To estimate the decline rate of the antibody concentration, the model accommodates the possibility of unobserved subclinical infections with Hib bacteria that cause increasing concentrations during the study period. The computations rely on Markov chain Monte Carlo simulation of the joint posterior distribution of the model parameters. The model is used to predict the duration of immunity to subclinical Hib infection and to a serious invasive Hib disease.

C-fos protein expression in the nucleus of the solitary tract correlates with cholecystokinin dose injected and food intake in rats

C-fos protein expression was investigated in the nucleus of the solitary tract (NTS) in response to increasing cholecystokinin (CCK) doses and food intake in rats by counting the number of c-fos protein positive cells in the NTS. C-fos protein expression in the NTS dose-dependently increased in response to CCK, the lowest effective dose being 0.1 microg/kg. The ED(50) for c-fos protein expression in the NTS in response to CCK was calculated to be 0.5 to 1.8 microg/kg, depending on the anatomical level of the NTS investigated. Food intake increased c-fos protein expression in the NTS, the maximum number of c-fos protein positive cells being reached at 90 min after the start of food intake. Regression analysis identified a positive correlation between c-fos protein expression and the amount of food intake. Our data indicate that subpopulations of the NTS that are activated by CCK or food intake are involved into the short-term regulation of food intake and the neural control of feeding by the caudal brainstem.

Multiplication of different Legionella species in Mono Mac 6 cells and in Acanthamoeba castellanii

Survival and distribution of legionellae in the environment are assumed to be associated with their multiplication in amoebae, whereas the ability to multiply in macrophages is usually regarded to correspond to pathogenicity. Since most investigations focused on Legionella pneumophila serogroup 1, we examined the intracellular multiplication of different Legionella species in Mono Mac 6 cells, which express phenotypic and functional features of mature monocytes, and in Acanthamoeba castellanii, an environmental host of Legionella spp. According to the bacterial doubling time in Mono Mac 6 cells and in A. castellanii, seven clusters of legionellae could be defined which could be split further with regard to finer differences. L. longbeachae serogroup 1, L. jordanis, and L. anisa were not able to multiply in either A. castellanii or Mono Mac 6 cells and are members of the first cluster. L. dumoffi did not multiply in Mono Mac 6 cells but showed a delayed multiplication in A. castellanii 72 h after infection and is the only member of the second cluster. L. steigerwaltii, L. gormanii, L. pneumophila serogroup 6 ATCC 33215, L. bozemanii, and L. micdadei showed a stable bacterial count in Mono Mac 6 cells after infection but a decreasing count in amoebae. They can be regarded as members of the third cluster. As the only member of the fourth cluster, L. oakridgensis was able to multiply slight in Mono Mac 6 cells but was killed within amoebae. A strain of L. pneumophila serogroup 1 Philadelphia obtained after 30 passages on SMH agar and a strain of L. pneumophila serogroup 1 Philadelphia obtained after intraperitoneal growth in guinea pigs are members of the fifth cluster, which showed multiplication in Mono Mac 6 cells but a decrease of bacterial counts in A. castellanii. The sixth cluster is characterized by intracellular multiplication in both host cell systems and consists of several strains of L. pneumophila serogroup 1 Philadelphia, a strain of L. pneumophila serogroup 2, and a fresh clinical isolate of L. pneumophila serogroup 6. Members of the seventh cluster are a strain of agar-adapted L. pneumophila serogroup 1 Bellingham and a strain of L. pneumophila serogroup 1 Bellingham which was passaged fewer than three times on BCYE alpha agar after inoculation and intraperitoneal growth in guinea pigs. In comparison to members of the sixth cluster, both strains showed a slightly enhanced multiplication in Mono Mac 6 cells but a reduced multiplication in amoebae. From our investigations, we could demonstrate a correlation between prevalence of a given Legionella species and their intracellular multiplication in Mono Mac 6 cells. Multiplication of members of the genus Legionella in A. castellanii seems to be dependent on mechanisms different from those in monocytes.

Eradication of poliomyelitis: when can one be sure that polio virus transmission has been terminated?

Most polio virus infections are silent. Vaccination reduces the incidence of infection, and the period between clinical cases of poliomyelitis becomes longer. As the point of eradication is approached, it becomes increasingly difficult to use the case-free period to determine whether silent infections have ceased. In this paper, the authors use stochastic computer simulations to relate case-free periods to the presence or absence of silent infections. After 2 years without paralytic cases in a population of 200,000 inhabitants, the probability for the presence of silent infections can still be as high as 38%. The case-free period must exceed 3 years before one can be 95% certain that there has been local extinction of the wild polio virus infection. Even after 5 years without cases, the probability of silent polio virus transmission can still be in the range of 0.1-1.0%.

Deterministic models for the eradication of poliomyelitis: vaccination with the inactivated (IPV) and attenuated (OPV) polio virus vaccine

Currently two polio vaccines, IPV and OPV, are in use which differ markedly in their epidemiological parameters. A simple epidemiological model in terms of ordinary differential equations is proposed to study the effects of vaccination campaigns using these vaccines. The numbers of interest are the reproduction number of the disease in the presence of vaccination and the critical vaccination coverage necessary to prevent an outbreak. For these numbers explicit representations are determined which can be used in comparing different vaccination strategies.

Differential length of Onchocerca volvulus infective larvae from the Cameroon rain forest and savanna

Infective larvae from the savanna strain of Onchocerca volvulus are significantly longer (662.6 +/- 66.8 microns; n = 99) than those from the forest strain (624.2 +/- 62.0 microns; n = 236). The length of the infective larvae is not influenced by the size, species or age post infectionem (pi) of the Simulium damnosum s. l. vectors nor by their localization in the fly's head, thorax or abdomen, the worm load per fly or the thoracic volume per larva. However, the lengths of infective larvae within one individual fly have a conspiciously low variance.

Giant sialolithiasis appearing as odontogenic infection

The dentist frequently is called on to diagnose pathoses of the head and neck region. Two reports of giant submandibular sialoliths that were originally diagnosed as submandibular space odontogenic infections are presented. Careful history, and physical and radiographic examinations are necessary to assure proper diagnosis and treatment of this condition.