ATP-dependent conformational dynamics in a photoactivated adenylate cyclase revealed by fluorescence spectroscopy and small-angle X-ray scattering.

Structural insights into the photoactivated adenylate cyclases can be used to develop new ways of controlling cellular cyclic adenosine monophosphate (cAMP) levels for optogenetic and other applications. In this work, we use an integrative approach that combines biophysical and structural biology methods to provide insight on the interaction of adenosine triphosphate (ATP) with the dark-adapted state of the photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata (OaPAC). A moderate affinity of the nucleotide for the enzyme was calculated and the thermodynamic parameters of the interaction have been obtained. Stopped-flow fluorescence spectroscopy and small-angle solution scattering have revealed significant conformational changes in the enzyme, presumably in the adenylate cyclase (AC) domain during the allosteric mechanism of ATP binding to OaPAC with small and large-scale movements observed to the best of our knowledge for the first time in the enzyme in solution upon ATP binding. These results are in line with previously reported drastic conformational changes taking place in several class III AC domains upon nucleotide binding.

The relationship between cognitive control and lexical conflict resolution in developmental dyslexia.

Previous studies have revealed that cognitive control functions contribute to the resolution of lexical interference. Both cognitive control (CC) deficits and reduced speed of lexical retrieval in Rapid Automatized Naming (RAN) tasks are characteristics of Developmental Dyslexia (DD), but it is still not fully understood how these deficits relate to each other and to reading problems. To examine this question, we tested adolescents with DD (n = 38), poor readers (PR; n = 25) and typical readers (TR; n = 33) matched on age and IQ, on CC functions with Stroop, Stop Signal, Simon, Backward Digit Span and n-back tasks and on lexical retrieval and lexical conflict resolution with RAN of pictures in semantically homogeneous vs. mixed trials. As expected, in the blocked RAN Task DD individuals showed longer naming times and a greater effect of lexical conflict resolution (indexed by difference scores of naming times in the homogeneous and mixed conditions) than TR participants. We also found significant group differences (TR = PR > DD) in CC measures. Naming time was associated with CC, while the lexical interference effect did not show any association with this set of abilities. These findings suggest that DD individuals show impairments in multiple cognitive functions, such as cognitive control, lexical retrieval and lexical conflict resolution. Our results also suggest that CC functions are involved in lexical retrieval, but we have not found evidence for their involvement in lexical conflict resolution processes.

Interferon alfa-2a maintenance after salvage autologous stem cell transplantation in atypical mycosis fungoides with central nervous system involvement.

Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma with unfavourable prognosis for patients with advanced stages of the disease. Refractory disease and advanced-stage disease require systemic therapy. We report on a rare case of an atypical predominantly CD8+ folliculotropic MF, a subtype of MF with poorer prognosis, in a 59-year-old woman. She was initially diagnosed with MF restricted to the skin, of T3N0M0B0/stage IIB according to the current World Health Organization-European Organisation for Research and Treatment of Cancer classification. First-line treatment with local percutaneous radiotherapy in combination with systemic interferon alfa-2a resulted in complete remission. However, 21 months later the disease progressed to T3N0M1B0/stage IVB with development of cerebral manifestation and thus very poor prognosis. Allogeneic stem cell transplantation (SCT) was not a therapeutic option due to the lack of a suitable donor. We initiated methotrexate and cytarabine chemotherapy, followed by high-dose chemotherapy with thiotepa and carmustine with autologous SCT. Despite rapid response and complete remission of the cerebral lesions, disease recurrence of the skin occurred soon after. Interestingly, readministration of interferon alfa-2a as a maintenance treatment after the salvage autologous SCT resulted in a durable complete remission during the follow-up period of currently 17 months after autologous SCT. What's already known about this topic? Mycosis fungoides is a primary cutaneous T-cell lymphoma with unfavourable prognosis for the advanced stages of the disease. A refractory course of disease requires systemic therapy. What does this study add? We report on an unusual case of a patient with mycosis fungoides with cerebral involvement, in which a durable complete remission was achieved upon autologous stem cell therapy and interferon alfa-2a maintenance therapy.

Better cardiorespiratory fitness associated with favourable metabolic control and health-related quality of life in youths with type 1 diabetes mellitus.

OBJECTIVE: to explore the relationship among health-related quality of life (HRQoL), clinical variables, anthropometric measures, physical activity and cardiorespiratory fitness in children and adolescents with type 1 diabetes.Furthermore, we aimed to find predictors of HRQoL and metabolic control. METHODS: A total of 106 patients (sex ratio: 1:1) with mean HbA1c of 8.55 (± 1.44) % and diabetes duration of 5.15 (± 3.24) years were assessed. The average age was 13.22 (± 3.08) years. RESULTS: We observed statistically significant negative medium correlation between HbA1c and VO2max (r = ­ 0.343; p = 0.000). There was statistically significant small positive correlation between the HRQoL and the maximal oxygen consumption (r = 0.208; p = 0.032). We found no significant correlation between the HbA1c and the patients' HRQoL. In the multiple linear regression analysis both the better metabolic control and the HRQoL was predicted by the VO2max, other variables had no effect. Physical activity level did not explain the HRQoL. Boys had significantly better HRQoL and less skinfold thickness than girls. CONCLUSION: Better cardiorespiratory fitness associated with both favourable metabolic control and better HRQoL of diabetic youths.Regular aerobic exercise improves the young patients' physical fitness and overall health status, and perception of health-related quality of life, respectively.

Dynamics of information access on the web.

While current studies on complex networks focus on systems that change relatively slowly in time, the structure of the most visited regions of the web is altered at the time scale from hours to days. Here we investigate the dynamics of visitation of a major news portal, representing the prototype for such a rapidly evolving network. The nodes of the network can be classified into stable nodes, which form the time-independent skeleton of the portal, and news documents. The visitations of the two node classes are markedly different, the skeleton acquiring visits at a constant rate, while a news document's visitation peaks after a few hours. We find that the visitation pattern of a news document decays as a power law, in contrast with the exponential prediction provided by simple models of site visitation. This is rooted in the inhomogeneous nature of the browsing pattern characterizing individual users: the time interval between consecutive visits by the same user to the site follows a power-law distribution, in contrast to the exponential expected for Poisson processes. We show that the exponent characterizing the individual user's browsing patterns determines the power-law decay in a document's visitation. Finally, our results document the fleeting quality of news and events: while fifteen minutes of fame is still an exaggeration in the online media, we find that access to most news items significantly decays after 36 hours of posting.

Measurement of the optical parameters of purple membrane and plant light-harvesting complex films with optical waveguide lightmode spectroscopy.

Purple membrane (bacteriorhodopsin) and plant light-harvesting complexes (LHCII) were dried on the optical waveguide sensor with varying thicknesses in a wide range (from 20 to several hundreds of nanometers) and the optical parameters were studied with optical waveguide lightmode spectroscopy. It was found that applying the approximate 4-layer mode equations for the measured effective refractive indices resulted in unacceptable results for the optical parameters: with increasing thickness the refractive index decreased monotonously from 1.5 to 1.1. Therefore an inverse waveguide numerical method was developed and used to obtain reliable results from the experiments. The inverse method yielded an approximately constant (1.53) refractive index independently of the thickness for the purple membrane and LHCII films. Light-induced changes in the optical parameters of the purple membrane and LHCII films were also studied. For purple membrane films the most significant effect is the change in refractive index and absorption. For LHCII films prolonged illumination induced irreversible structural changes, most probably of thermo-optic origin.

Bacteriorhodopsin photocycle kinetics analyzed by the maximum entropy method.

A maximum entropy method (MEM) was developed for the study of the bacteriorhodopsin photocycle kinetics. The method can be applied directly to experimental kinetic absorption data without any assumption for the number of the intermediate states taking part in the photocycle. Though this method does not give a specific kinetics, its result is very useful for selection between possible photocycle kinetics. Using simulated data, it is shown that MEM gives correct results for the number of the intermediate states and the amplitude distributions around the characteristic lifetimes. Analyzing experimental absorption data at five different wavelengths, MEM gives seven or eight characteristic lifetimes, which means that at least so many distinct intermediate states exist during the photocycle. Many possible photocycle kinetic models were studied and compared with the MEM result. The best agreement was found with a branching photocycle model of eight intermediate states (K, L, M(1), M(2), M(3), M(4), N, O). The branching occurs at the L intermediate state (M(1) and M(2) being in one branch and M(3) and M(4) in the other branch), but at high pH it occurs already at the K state.

Application of the maximum entropy method to absorption kinetic rate processes.

The maximum entropy method, originally developed for astronomical image restoration, has already been successfully applied to a variety of biophysical problems. Through numerical inverse Laplace transformation, the method determines the lifetime distribution function with the largest informational entropy. Starting from a flat distribution, it results in the consistent selection of a single distribution from the numerous possible ones that correctly fit the data. In this paper, we discuss the application of the method to kinetic processes that have both rise and decay components, and test the algorithm with different signal to noise ratio generated data. It is proved that the mass conservation constraint can be taken into account by reducing the search to a lower dimensional subspace. The effect of noise on the width of lifetime distribution is studied and it is shown that an inherent entropy connected to the underlying kinetics can be separated from the noise generated entropy. The possibility of the application of the method to the photocycle kinetics of bacteriorhodopsin is also shown.

Increased frequency of intracellular interleukin (IL)-13 and IL-10, but not IL-4, expressing CD4+ and CD8+ peripheral T cells of patients with atopic dermatitis.

BACKGROUND: A number of studies exist demonstrating the increased expression of type 2 cytokines and decreased capacity to produce interferon-gamma (IFN-gamma) in peripheral blood mononuclear cells (PBMCs) of patients with atopic dermatitis (AD). OBJECTIVES: To clarify the results of recent studies concerning the role of interleukin (IL)-4 and IL-13 in PBMCs of AD patients, we analysed the activation status of lymphocyte subpopulations. METHODS: We measured the intracellular expression and serum levels of certain type 1 and type 2 cytokines, using cell surface and intracellular cytokine staining, flow cytometry and enzyme-linked immunosorbent assay techniques. RESULTS: The frequency of IL-10 and IL-13 producing CD4+ and CD8+ T cells was significantly higher in patients with AD, while the frequency of IFN-gamma secreting helper and cytotoxic T cells was significantly lower in patients with AD than in control subjects. The serum levels of IL-10 and IL-13 were also significantly increased. There were no significant differences observed between the experimental groups in the frequency of IL-4 producing CD4+ and CD8+ cells. CONCLUSIONS: This study demonstrates a type 2 cytokine production in the CD4+ and CD8+ T cells of AD patients, which is characterized by an elevated IL-13, but not by IL-4 secretion, and by an increased level of the immunoregulatory IL-10, which can contribute to a decrease in IFN-gamma expression.

Prevalence, genotype distribution and outcome of hepatitis C infections among the employees of the Hungarian Central Hospital for infectious diseases.

Blood samples from 477 hospital workers (HWs) at the Central Hospital for Infectious Diseases, Budapest, Hungary were tested for hepatitis C virus (HCV) antibodies by enzyme immunoassay (EIA), and 13 (2.7%) of these were found to be HCV antibody positive. Ten (2.7%) were from nursing/housekeeping staff and three (2.9%) from medical staff. HCV antibody positive HWs were detected in 10 of 17 work places, and the prevalence rates in these departments or units varied between 1.2% and 6.5%. The prevalence increased gradually with increasing age, being 0% in these under 21 years of age and 9.5% in those above 50 years of age. Eleven (85%) of 13 HCV antibody positive HWs had HCV RNA in their sera, four of them intermittently during the follow-up period. HCV genotype 1 was present in two HWs, 1b in six HWs, 3a in one HW and 4 in two HWs. Chronic hepatitis C has developed in six (46%) HCV antibody positive HWs. Although the source of infection through needlestick could only be traced directly in one case, circumstantial evidence indicated that the majority of infections were occupationally acquired, originating from percutaneous or mucocutaneous exposure.

Relative variation to received dose of some erythrocytic and leukocytic indices of human blood as a result of low-level laser radiation: an in vitro study.

OBJECTIVE: This study investigated the in vitro effects of low-level laser radiation (LLLR) on selected rheologic constants of the human blood. The variations of CBC parameters to the received dose were determined, as well as of blood viscosity (an erythrocyte aggregation index), as a research method for some structural alteration of blood proteins. This was also confirmed by the electrophoretic study of plasma proteins from the irradiated blood. METHODS: Fresh blood samples (whole blood) from 16 adult regular blood donors were irradiated with a He-Ne laser (lambda = 632.8 nm; power output = 6 mW; mean irradiance on blood samples approximately 180 mW.cm-2; beam spot diameter approximately 2 mm), operating in continuous wave. Doses ranged between 0 (control sample) and 9.346 J.cm-3.EDTA (for CBC and viscosity measurements) or citrate (for electrophoresis) anticoagulant was used. Measurements were performed before (control samples) and after irradiation. In most of the cases, the measurements were made immediately after irradiation. In some cases, the measurements were made after 24 or 48 h after irradiation, respectively, to conclude whether the modifications caused from irradiation occur in time, or immediately after irradiation. RESULTS: Following irradiation, marked variations of some erythrocyte and leukocyte indices and changes of the erythrocyte aggregation (viscosity), as a function of received dose, were observed. Significant differences between control and irradiated blood samples were found for the following rheologic factors: RBC (in 22.2% of cases); HGB (26.8%); HCT (82.4%); MONO and GRAN (36.7%); viscosity (82.5%). From the plasma proteins: albumin (22.2%); alpha 1 globulin and gamma globulin (18.5%); fibrinogen (70.4%). In most of the cases, remarkable effects (maxima) were noticed around 1.2 J.cm-3 dose value. We consider this dose value as optimal, one that can lead to beneficial effects. The cell membrane integrity was not affected from irradiation, for doses between 0 and 9.346 J.cm-3, and will probably not even be affected at higher doses (see MCV and MCHC behavior). CONCLUSIONS: The effect of LLLR on red blood cells confirms the nonresonant mechanism of this biostimulating effect, by the changes occurring in the cell membrane (in our case, blood cells), by revitalizing of red blood cell functional capacities and by several biochemical effects at the membrane's level. These are to be studied thoroughly in future studies. The physical-biochemical and biological effects caused by LLLR on blood can influence the physical-chemical parameters needed for the long-term storage of blood products. These effects can also lead to a quicker revitalization of the erythrocyte membrane (which was subjected to the action of some physical and biochemical factors during the preservation process), to perform its oxyphoric function in transfusion procedures.

Flexibility of myosin-subfragment-1 in its complex with actin as revealed by fluorescence resonance energy transfer.

The flexibility of the acto-myosin complex in rigor conditions was characterized by measuring the temperature profile of normalized fluorescence resonance energy transfer efficiency, f' [Somogyi, B., Matkó, J., Papp, S., Hevessy, J., Welch, G.R. & Damjanovich, S. (1984) Biochemistry 23, 3403-3411]. Fluorescence acceptors were introduced to the Cys374 residues of actin and the donors were covalently attached either to Cys707 in the catalytic domain or to Cys177 in the essential light-chain of myosin S1. Fluorescence resonance energy transfer measurements revealed that the protein matrix between Cys374 of actin and Cys707 of S1 is rigid. In contrast, the link between the catalytic and light-chain-binding domains in myosin S1 is flexible. We have recently shown that the positional distribution of Cys707 was narrow relative to the actin filament, while that of the Cys177 was broad. Accordingly, the broad positional distribution of Cys177 is likely to be due to the large flexibility of the link between the catalytic and light-chain-binding domains. This flexibility is probably essential for the interdomain reorganization of the myosin head during the force generation process and for accommodating the symmetry difference between actin and myosin filaments to allow the formation of cross-bridges.

Conformational distributions and proximity relationships in the rigor complex of actin and myosin subfragment-1.

Cyclic conformational changes in the myosin head are considered essential for muscle contraction. We hereby show that the extension of the fluorescence resonance energy transfer method described originally by Taylor et al. (Taylor, D. L., Reidler, J., Spudich, J. A., and Stryer, L. (1981) J. Cell Biol. 89, 362-367) allows determination of the position of a labeled point outside the actin filament in supramolecular complexes and also characterization of the conformational heterogeneity of an actin-binding protein while considering donor-acceptor distance distributions. Using this method we analyzed proximity relationships between two labeled points of S1 and the actin filament in the acto-S1 rigor complex. The donor (N-[[(iodoacetyl)amino]ethyl]-5-naphthylamine-1-sulfonate) was attached to either the catalytic domain (Cys-707) or the essential light chain (Cys-177) of S1, whereas the acceptor (5-(iodoacetamido)fluorescein) was attached to the actin filament (Cys-374). In contrast to the narrow positional distribution (assumed as being Gaussian) of Cys-707 (5 +/- 3 A), the positional distribution of Cys-177 was found to be broad (102 +/- 4 A). Such a broad positional distribution of the label on the essential light chain of S1 may be important in accommodating the helically arranged acto-myosin binding relative to the filament axis.

Effect of low-level laser radiation on some rheological factors in human blood: an in vitro study.

OBJECTIVE: The purpose of this study was to investigate the in vitro effects of low-level laser radiation (LLLR) on some rheological factors of the human blood, such as complete blood count (CBC) parameters and blood sedimentation rate (BSR). We were mainly concerned with the alterations caused by LLLR action on blood cells (erythrocytes and leukocytes) of fresh blood obtained from apparently healthy adult patients. We used low doses ranging between 0.80 J x cm(-3) and 4.40 J x cm(-3), at the very low-power densities of the laser radiation, so as not to damage the cell structure and not to alter in an undesired manner their functions. METHODS: Blood samples were taken from 22 volunteers. Where health problems existed, they were indicated for each case. The parameters mentioned above were measured before (control samples) and after irradiation. A He-Ne laser, operating in continuous wave, as a radiation source (632.8 nm, 1 mW, intensity of 8 x 10(-2) W x sr(-1), mean power density incident on blood samples around 30 mW x cm(-2), beam spot diameter 2 mm) was used. The measurements were performed immediately after irradiation. Only the erythrocyte complex was irradiated. EDTA anticoagulant was used. RESULTS: The measurements using a computerized hemoanalyzer type SERONO showed significant differences between control and irradiated blood samples concerning the following parameters: RBC (in 22% of cases), HGB (47.3%), HCT (84.2%), RDW (11%), PLT (5.26%), MPV (33.3%), WBC (5.26%), MONO (26.3%), and GRAN (63.15%). In the case of BSR (44%), the significant differences were noticed especially in the cases of patients suffering from some acute or chronic diseases. Nonsignificant differences were noticed in the cases of MCV, MCH, MCHC, RDW, and LYMPH. CONCLUSIONS: This study has shown that LLLR, even though used at low doses and low power densities, produced some changes of the rheological factors of the blood, as follows: a revitalizing and regenerating effect on mitosis stimulation and a nondamaging and biostimulating effect on the cell membrane (by keeping unmodified MCV, MCH, and MCHC). In 3 cases out of 22, hemolysis (complete or partially) occurred, but we are not yet sure whether this was caused by laser exposure or by certain environmental physical factors.

[Late detection of vascular injuries]. / Idóben fel nem ismert érsérülések.

Generally recognizing of traumatical vascular injuries isn't difficult since clinical signs and symptoms show them unambiguously. For some time-mainly in case of blunt and shot wounds-lacking unanimous signs the vascular injuries can't be diagnosed. Later on appearing symptoms as complications raise the chance of existence of an earlier vascular injury. In case of three patients the elapsing time between the vascular injury and its diagnosis was 4 weeks, 3 years and more than 50 years.

[Topical administration of metronidazole gel as an effective therapy alternative in chronic Demodex blepharitis--a case report]. / Lokale Anwendung von Metronidazol-Gel als wirksame Therapiealternative in der Behandlung der chronischen Demodex-Blepharitis--ein Fallbericht.

BACKGROUND: Blepharoconjunctivitis is the commonest manifestation of ocular rosacea. Cilia epilation proves Demodex folliculorum, considered an etiologic factor in rosacea. Complications and differential diagnosis include dry eyes, seborrheic, bacterial and allergic blepharoconjunctivitis. Treatment involves lid scrubs and mercury ointment, its duration is limited to 6 weeks under frequent control due to corneal toxicity of mercury. HISTORY AND SIGNS: 30-year-old female with complaint of red, irritated eyes for 21 years, resistant to antibiotics and antiallergics. General medical history unremarkable, mercury allergy. Acuity: R/L 20/20. Biomicroscopy: red, thickened eyelid margins, crusty debris on rarefied, partially broken lashes, conjunctival telangiectasia, low tear meniscus, further ophthalmologic examination unremarkable. DIAGNOSIS: chronic Demodex blepharoconjunctivitis. THERAPY AND OUTCOME: Conventional treatment was contraindicated due to mercury allergy. Alternative oral minocycline 100 mg daily brought no subjective nor objective relief. Combination of lid scrubs and 2% Metronidazole gel relieved symptoms and halved number of mites after 1 month, lashes grew again after 2 months. Treatment was discontinued after 6 months as Demodex folliculorum proof remained negative. No relapse occurred during 1 year. CONCLUSIONS: Topical Metronidazole 2% proved to be an effective treatment of chronic Demodex blepharoconjunctivitis in our case and thus may offer a new and save alternative to existing therapies. Neither ocular nor systemic side effects occurred. Controversial theories on the aetiology of blepharitis are discussed.

[Lisch nodules. Markers of neurofibromatosis 1 and immunohistochemical references for neuroectodermal differentiation]. / Lisch-Knötchen. Marker der Neurofibromatose I und immunhistochemische Hinweise für eine neuroektodermale Differenzierung.

Iris nodules in neurofibromatosis I have become an important tool in the differential diagnosis of phakomatoses. The clinical appearance and importance of these nodules first recognized by Karl Lisch in Munich in 1937. The diagnosis and differential diagnosis of Lisch nodules are illustrated. The importance of iris nodules in genetic counselling of patients and their relatives is discussed, with emphasis on monosymptomatic cases. Histologically Lisch nodules are formed by aggregations of oval to round cells that form dome-shaped papules on the anterior layer of the iris. Immunohistochemically these cells are characterized by positive staining with antibodies against vimentin and S-100 protein. This proves their ectodermal differentiation. Thus Lisch nodules can be seen as a direct manifestation of neuroectodermal disturbances in neurofibromatosis I.

[Screening for hepatitis C of hospital personnel at the Szent László Hospital of Budapest]. / Egészségügyi dolgozók C hepatitis szürövizsgálata a Szent László Kórházban.

UNLABELLED: The health-care workers are known to be at risk of occupational transmission of blood-borne viruses. The goal of the investigation was to determine the prevalence of hepatitis C virus (HCV) antibody and the occupational risk of HCV transmission among personnel at the Central. Hospital for Infectious Diseases, Budapest, Hungary. Serum samples of 409 health-care workers were tested for antibody to HCV with second and third generation ELISA-s and anti-HCV positive samples were confirmed with Western Blot Line EIA. A total of 10 (2.4%) of the health-care workers were confirmed to be anti-HCV positive. The prevalence of anti-HCV increased with advancing age: zero under 20 yr age group (N = 0/15), 0.9% in 21-30 yr age group (N = 1/112), 1.8% in 31-40 yr age group (N = 2/111), 3.1% in 41-50 yr age group (N = 3/96) and 4.0% in above 50 yr age group (N = 3/75). We found anti-HCV positive hospital worker in 9 out of 17 departments. The prevalence of hepatitis C antibody was 7.1-1.9% among the personnel of internal departments, pathology, intensive care unit and pediatric departments. No anti-HCV positive health-care worker was found in the surgery and laboratories. None of the physicians tested was seropositive for HCV. Eight of the nurses, one of the sanitary personnel and one pathological technician were seropositive for HCV. Two nurses developed a chronic C hepatitis after a needlestick accident. CONCLUSIONS: 1. The hospital personnel is at risk for HCV infection. 2. The occupational risk of HCV infection increases with age but the risk is considerable lower than that of hepatitis B infection. 3. The occupational risk is highest among the workers of the chronic internal department, pathology and intensive care unit. 4. The nurses are at higher risk of HCV infection than the physicians. 5. The needlestick injury is associated with an increased risk for acquiring HCV infection.

[Effect of vaccination on the risk of hepatitis B infection in hospital personnel]. / A védöoltás hatás a hepatitis B vírusfertözés kockázatára egészségügyi dolgozókban.

The effect of vaccination on acute B hepatitis, on HBsAg carrier state and on the seropositivity of hepatitis B virus was examined in the personnel of the St. László Hospital in two periods. Human plasma origin vaccine was introduced gradually from 1985 to 1989. From 1989 till the end of 1994 recombinant vaccines were provided for all workers. A total of 10577 tests were done from 3524 sera of 2019 hospital workers. A total of 2.4% of the workers developed acute hepatitis. Hepatitis B was confirmed most frequently (29%) of hepatitis cases. In the first and second period HBsAg positivity was 4.1% and 2.1% (P = 0.1), respectively. Although the annual frequency of acute hepatitis has not changed, that of HBsAg positivity showed a decreasing tendency during the nine years of the study. The prevalence of hepatitis B markers could be characterized by a significant rise in close correlation with age. The protective effect of vaccination is markedly reflected by the altered prevalence of hepatitis B virus markers in the different age groups. At the age of fifty and above hepatitis B seropositivity was 47.2% and 36.4% in the first and second period (P = 0.1), respectively. The frequency of seropositivity was the highest among the workers of surgical, pathological, hepatological departments and ICU. Our results show that vaccination is an effective tool in hepatitis B prevention. Every effort has to be made to promote hepatitis B immunity to all health care workers and strictly follow hygienic preventive measures.

The influence of the pH-value on the growth of Brevibacterium epidermidis in continuous culture.

Brevibacterium epidermidis is a major component of the bacterial flora of certain skin surface biotopes, characterized by a comparatively high pH-value. The presence of Brevibacterium epidermidis seems to be linked to the production of malodour. Skin surface pH has been found to be a major factor of bacterial growth on the skin. In order to find out if this might also apply to Brevibacterium epidermidis, this microorganism was grown in vitro in continuous culture using a chemostat. Specific growth rate and density of colony forming units were well correlated. While the organism grew readily from pH 5.5 to 8.5, this was not the case with a pH of 5.0. Thus pH-shifts induced by cosmetic procedures can only prevent unpleasant body odour due to abundant growth of bacteria if the pH-value is decreased to 5.0 or less.