Mechanistic insights into the regulation of cell wall hydrolysis by FtsEX and EnvC at the bacterial division site

The peptidoglycan (PG) cell wall produced by the bacterial division machinery is initially shared between the daughters and must be split to promote cell separation and complete division. In gram-negative bacteria, enzymes that cleave PG called amidases play major roles in the separation process. To prevent spurious cell wall cleavage that can lead to cell lysis, amidases like AmiB are autoinhibited by a regulatory helix. Autoinhibition is relieved at the division site by the activator EnvC, which is in turn regulated by the ATP-binding cassette (ABC) transporter-like complex called FtsEX. EnvC is also known to be autoinhibited by a regulatory helix (RH), but how its activity is modulated by FtsEX and the mechanism by which it activates the amidases have remained unclear. Here, we investigated this regulation by determining the structure of Pseudomonas aeruginosa FtsEX alone with or without bound ATP, in complex with EnvC, and in a FtsEX-EnvC-AmiB supercomplex. In combination with biochemical studies, the structures reveal that ATP binding is likely to activate FtsEX-EnvC and promote its association with AmiB. Furthermore, the AmiB activation mechanism is shown to involve a RH rearrangement. In the activated state of the complex, the inhibitory helix of EnvC is released, freeing it to associate with the RH of AmiB, which liberates its active site for PG cleavage. These regulatory helices are found in many EnvC proteins and amidases throughout gram-negative bacteria, suggesting that the activation mechanism is broadly conserved and a potential target for lysis-inducing antibiotics that misregulate the complex.

Development of a fluid-bed coating process for soil-granule-based formulations of Metarhizium brunneum, Cordyceps fumosorosea or Beauveria bassiana

AIM

Granule-based products of solid state fermented micro-organisms are available for biocontrol. Because liquid fermentation has several advantages, we investigated fluid-bed coating with liquid fermented biomass.

METHODS AND RESULTS

Biomass containing mycelium or mycelium and submerged spores of the entomopathogenic fungi Metarhizium brunneum, Cordyceps fumosorosea and Beauveria bassiana were produced in liquid culture, separated and different biomass concentrations were adjusted. Based on the examined thermo-tolerance, we defined fluid-bed coating adjustments and investigated granule colonization and sporulation on granules. Granule colonization depended on the biomass concentration and strain. For C. fumosorosea and B. bassiana, concentrations of 0·003%_{dry weight} resulted in nearly 100% granule colonization, for M. brunneum with concentrations of 0·7%_{dry weight} in only 50%. The conidiation on granules in sterile soil was highly influenced by the moisture content. Because the granule colonization of M. brunneum was unsatisfactory, we pre-coated nutrients followed by coating with biomass, submerged spores or conidia. Malt extract had a positive effect on the granule colonization for biomass and submerged spores. Furthermore, aerial conidia can also be coated.

CONCLUSIONS

Fluid-bed coating of fungal biomass is suitable for the development of granules.

SIGNIFICANCE AND IMPACT OF THIS STUDY

With this technology, cost-efficient biocontrol products can be developed.

Experimentelle Forschung an der Klinik und Poliklinik für Dermatologie und Venerologie

Seit Antritt von Prof. Dr. med. Steffen Emmert als Ordinarius der Klinik und Poliklinik für Dermatologie und Venerologie im Jahr 2015 konnte das dermatologische Forschungslabor sukzessive aufgebaut und erweitert werden. Im Einklang mit dem onkologischen Schwerpunkt der Universitätsmedizin Rostock sowie dem von der Landesregierung forcierten „Gesundheitsland Mecklenburg-Vorpommern“ wird grundlagenorientierten und translationalen Projekten nachgegangen. Das vorwiegend drittmittelfinanzierte und stetig wachsende Forschungsteam bearbeitet diverse Fragestellungen in den Bereichen der Dermato-Onkologie, Plasmamedizin und seltenen Hauterkrankungen. Inzwischen auf einem soliden Fundament stehend, befindet sich der Forschungsbereich weiterhin in einem dynamischen Entwicklungsprozess. Nicht nur personell, sondern auch thematisch und methodisch wird er derzeit durch die Integration weiterer Arbeitsgruppen unter der Leitung von Ärzten aus der Klinik ergänzt und ausgebaut. Diverse Kollaborationen an der Universitätsmedizin Rostock und im Land zeugen von einem freundlichen, unterstützenden und kollegialen Umfeld, das die Integration am Standort befördert hat.

[Current indications for plasma therapy in dermatology]

BACKGROUND

Plasma medicine is gaining increasing interest and provides a multitude of dermatological applications. Cold atmospheric pressure plasma (CAP) can be used in clinical applications without harming the treated tissue or in a tissue destructive manner. It consists of a complex mixture of biologically active agents, which can act synergistically on the treated material or tissue.

OBJECTIVES

A summary of the current research findings regarding dermatological applications of CAP is provided.

METHODS

Literature on CAP applications in dermatology has been screened and summarized.

RESULTS

CAP exerts antimicrobial, tissue-stimulating, blood-flow-stimulating but also pro-apoptotic effects. By exploiting these properties, CAP is successfully applied for disinfection and treatment of chronic ulcerations. Furthermore, positive effects of CAP have been shown for the treatment of tumors, actinic keratosis, scars, ichthyosis, atopic eczema as well as for alleviation of pain and itch.

CONCLUSIONS

While the use of CAP for disinfection and wound treatment has already moved into clinical practice, further applications such as cancer treatment are still exploratory.

Iron Regulation by Molidustat, a Daily Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor, in Patients with Chronic Kidney Disease

BACKGROUND/AIMS

The current treatment for anemia associated with chronic kidney disease (CKD) includes the administration of erythropoiesis stimulating agents (ESAs) combined with iron supplementation. Molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, has potential to treat anemia associated with CKD through increased erythropoietin production and improved iron availability. Here, we report the effect of molidustat on iron metabolism.

METHOD

Parameters of iron metabolism were monitored in three 16-week, randomized, controlled, phase 2 studies assessing the safety and efficacy of molidustat in the treatment of anemia associated with CKD in different populations: treatment-naïve and previously ESA-treated patients not on dialysis, and previously ESA-treated patients on hemodialysis. Iron supplementation was left at the discretion of the investigator.

RESULTS

In treatment-naïve patients not on dialysis, transferrin saturation (TSAT), hepcidin, ferritin, and iron concentrations decreased with molidustat, whereas total iron binding capacity (TIBC) increased. Similar results were observed in previously ESA-treated patients not on dialysis, although changes in those parameters were larger in treatment-naïve than in previously ESA-treated patients. In previously ESA-treated patients receiving hemodialysis, hepcidin concentration and TIBC remained stable with molidustat, whereas TSAT and ferritin and iron concentrations increased. Generally, similar trends were observed in secondary analyses of subgroups of patients not receiving iron supplementation.

CONCLUSIONS

Molidustat is a potential alternative to standard treatment of anemia associated with CKD, with a different mechanism of action. In patients not receiving dialysis, molidustat increases iron availability. In patients receiving hemodialysis, further investigation is required to understand fully the mechanisms underlying iron mobilization associated with molidustat.

Long-Term Efficacy and Safety of Molidustat for Anemia in Chronic Kidney Disease: DIALOGUE Extension Studies

BACKGROUND

Molidustat, a novel hypoxia-inducible factor-prolyl hydroxylase inhibitor, is being investigated for the treatment of anemia associated with chronic kidney disease (CKD). The efficacy and safety of molidustat were recently evaluated in three 16-week phase 2b studies. Here, we report the results of two long-term extension studies of molidustat.

METHODS

Both studies were parallel-group, open-label, multicenter studies of ≤36 months' duration, in patients with anemia due to CKD, and included an erythropoiesis-stimulating agent as active control. One study enrolled patients not receiving dialysis (n = 164), and the other enrolled patients receiving hemodialysis (n = 88). The primary efficacy variable for both studies was change in blood hemoglobin (Hb) level from baseline to each post-baseline visit, and safety outcomes included adverse events (AEs).

RESULTS

In patients not on dialysis, the mean ± SD Hb concentrations at baseline were 11.28 ± 0.55 g/dL for molidustat and 11.08 ± 0.51 g/dL for darbepoetin. The mean ± SD blood Hb concentrations throughout the study (defined as mean of each patient's overall study Hb levels) were 11.10 ± 0.508 and 10.98 ± 0.571 g/dL in patients treated with molidustat and darbepoetin, respectively. Similar proportions of patients reported at least one AE in the molidustat (85.6%) and darbepoetin (85.7%) groups. In patients on dialysis, mean ± SD Hb levels at baseline were 10.40 ± 0.70 and 10.52 ± 0.53 g/dL in the molidustat and epoetin groups, respectively. The mean ± SD blood Hb concentrations during the study were 10.37 ± 0.56 g/dL in the molidustat group and 10.52 ± 0.47 g/dL in the epoetin group. Proportions of patients who reported at least one AE were 91.2% in the molidustat group and 93.3% in the epoetin group.

CONCLUSIONS

Molidustat was well tolerated for up to 36 months and appears to be an effective alternative to darbepoetin and epoetin in the long-term management of anemia associated with CKD.

Effects of Molidustat in the Treatment of Anemia in CKD

BACKGROUND AND OBJECTIVES

The efficacy and safety of molidustat, a hypoxia-inducible factor-prolyl hydroxylase inhibitor, have been evaluated in three 16-week, phase 2b studies in patients with CKD and anemia who are not on dialysis (DaIly orAL treatment increasing endOGenoUs Erythropoietin [DIALOGUE] 1 and 2) and in those who are on dialysis (DIALOGUE 4).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

DIALOGUE 1 was a placebo-controlled, fixed-dose trial (25, 50, and 75 mg once daily; 25 and 50 mg twice daily). DIALOGUE 2 and 4 were open-label, variable-dose trials, in which treatment was switched from darbepoetin (DIAGLOGUE 2) or epoetin (DIALOGUE 4) to molidustat or continued with the original agents. Starting molidustat ranged between 25-75 and 25-150 mg daily in DIAGLOGUE 2 and 4, respectively, and could be titrated to maintain hemoglobin levels within predefined target ranges. The primary end point was the change in hemoglobin level between baseline and the mean value from the last 4 weeks of the treatment period.

RESULTS

In DIAGLOGUE 1 (n=121), molidustat treatment was associated with estimated increases in mean hemoglobin levels of 1.4-2.0 g/dl. In DIAGLOGUE 2 (n=124), hemoglobin levels were maintained within the target range after switching to molidustat, with an estimated difference in mean change in hemoglobin levels between molidustat and darbepoetin treatments of up to 0.6 g/dl. In DIAGLOGUE 4 (n=199), hemoglobin levels were maintained within the target range after switching to molidustat 75 and 150 mg, with estimated differences in mean change between molidustat and epoetin treatment of -0.1 and 0.4 g/dl. Molidustat was generally well tolerated, and most adverse events were mild or moderate in severity.

CONCLUSIONS

The overall phase 2 efficacy and safety profile of molidustat in patients with CKD and anemia enables the progression of its development into phase 3.

Lipoprotein activators stimulate Escherichia coli penicillin-binding proteins by different mechanisms

In Escherichia coli , the bifunctional penicillin-binding proteins (PBPs), PBP1A and PBP1B, play critical roles in the final stage of peptidoglycan (PG) biosynthesis. These synthetic enzymes each possess a PG glycosyltransferase (PGT) domain and a transpeptidase (TP) domain. Recent genetic experiments have shown that PBP1A and PBP1B each require an outer membrane lipoprotein, LpoA and LpoB, respectively, to function properly in vivo. Here, we use complementary assays to show that LpoA and LpoB each increase the PGT and TP activities of their cognate PBPs, albeit by different mechanisms. LpoA directly increases the rate of the PBP1A TP reaction, which also results in enhanced PGT activity; in contrast, LpoB directly affects PGT domain activity, resulting in enhanced TP activity. These studies demonstrate bidirectional coupling of PGT and TP domain function. Additionally, the transpeptidation assay described here can be applied to study other activators or inhibitors of the TP domain of PBPs, which are validated drug targets.

[Attitudes towards predictive genetic testing for Alzheimer's disease]

Most neuropsychiatric disorders have a complex aetiology. Discovery of the underlying genetics will provide insights into the disorders and allow the subsequent development of therapeutic interventions based upon an understanding of causality. The first vulnerability genes in Alzheimer's disease (AD) have been identified. The contribution of each vulnerability gene to the disorder is limited and does not enable prediction of course and onset in individual cases, only modification of the a priori risk. However, people may wish to be informed about this modification. Professionals have not favoured this form of predictive testing due to an awareness of its limitations and its potential for harm. However, little is known about public attitudes and understanding of such genetic testing in neuropsychiatric disorders. The aim of our study was to assess the attitudes of the general population and to explore the influence on these attitudes of knowledge about the illness and the understanding of risk information. In our study, a representative sample of the German general population (n=2001), relatives of patients with Alzheimer's disease (n=101) and physicians (n=43) were interviewed about their attitudes towards genetic tests for Alzheimer's disease and their perception and interpretation of risk information. To assess the influence of genetic counselling on these factors, 234 people were questioned before, and four weeks after, they were provided with detailed relevant information. Our results indicate that a substantial proportion of the German population (57%) is in favour of psychiatric genetic testing for AD in general. Even when the explanatory power of a genetic test is limited, a substantial proportion of the population (47%) expressed an interest in genetic testing. Counselling slightly decreased the interest in having a genetic test for oneself (from 47% to 38%). Physicians were more hesitant than both relatives and the general population concerning predictive genetic testing. Only a minority (11%) favoured prenatal genetic testing. Our results also show that both knowledge about AD and the capacity to interpret risk estimates are limited. While physicians' estimation of their personal risk for developing AD approximated to the actual average risk for the population, people in the general population and the relatives of AD patients tended to overestimate their personal risk. However, most of the general population still perceived this risk as average or low. While most physicians could correctly interpret information regarding the probability of risk, only one third of AD patients' relatives or members of the general population could. As the decision of an individual to undergo predictive testing relies mainly on his understanding of risk, the ability to correctly interpret risk information will be of crucial importance in the future. From a medical perspective, the prevailing approach of professional associations to genetic testing appears reasonable and therefore should not be changed at present.

1-Antitrypsin inhalation reduces airway inflammation in cystic fibrosis patients

The airways of cystic fibrosis (CF) patients are characterised by neutrophils that release high amounts of elastase overwhelming the local antiprotease shield. Inhalation of alpha(1)-antitrypsin (AAT) may restore the protease-antiprotease balance and attenuate airway inflammation in CF airways. The aims of the present study were: 1) to assess the best deposition region for inhaled AAT by two different inhalation strategies; and 2) to examine the effect of 4 weeks of AAT inhalation on lung function, protease-antiprotease balance and airway inflammation in CF patients. In a prospective, randomised study, 52 CF patients received a daily deposition by inhalation of 25 mg AAT for 4 weeks targeting their peripheral or bronchial compartment. The levels of elastase activity, AAT, pro-inflammatory cytokines, neutrophils, immunoglobulin G fragments and the numbers of Pseudomonas aeruginosa were assessed in induced sputum before and after the inhalation period. Inhalation of AAT increased AAT levels and decreased the levels of elastase activity, neutrophils, pro-inflammatory cytokines and the numbers of P. aeruginosa. However, it had no effect on lung function. No difference was found between the peripheral and bronchial inhalation mode. In conclusion, although no effect on lung function was observed, the clear reduction of airway inflammation after alpha(1)-antitrypsin treatment may precede pulmonary structural changes. The alpha(1)-antitrypsin deposition region may play a minor role for alpha(1)-antitrypsin inhalation in cystic fibrosis patients.

The potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions

Matrix-producing bone lesions consist of a wide variety of benign and malignant conditions. With respect to morphology, an overlap exists between benign and malignant bone tumors that causes difficulties in the final determination of the tumor. This study was conducted to show the potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions. Thirty benign bone tumors were evaluated by conventional comparative genomic hybridization. To test its diagnostic reliability, 5 additional cases were analyzed, all with differential diagnostic difficulties related to morphology and radiology. All were ultimately diagnosed as malignant sarcomas, and unbalanced alterations were detected. In contrast benign tumors or tumor-like lesions did not reveal any chromosomal alterations. Comparative genomic hybridization is a useful adjunct in the complicated differential diagnostic algorithms of matrix-producing bone tumors.

Psychosocial work factors and dementia

AIMS

To evaluate the association between psychosocial workplace factors and dementia in a case-control study.

METHODS

Patients with dementia (aged 55-99 years) were recruited from 23 general practices in the city of Frankfurt-on-Main and surrounding area in 1998-2000. Of these, 108 were suffering from possible Alzheimer's disease, 59 from possible vascular dementia, and 28 from secondary or unclassified dementia. A total of 229 control subjects (aged 60-94 years) was recruited from the same study region: 122 population controls and 107 dementia-free ambulatory patients. A detailed job history was elicited in a structured personal interview (next-of-kin interviews of cases). Psychosocial work exposure was assigned to cases and control subjects by linking lifetime job histories with a Finnish job-exposure matrix. Data were analysed using logistic regression, to control for age, region, sex, dementia in parents, education, smoking, and the psychosocial network at age 30.

RESULTS

There were decreased odds ratios for high challenge at work, high control possibilities at work, and high social demands at work. High risks for error at work revealed a significant positive association with the diagnosis of dementia. Restriction of the analysis to cases with possible Alzheimer's disease or to cases with possible vascular dementia led to similar results.

CONCLUSIONS

These results support a role for psychosocial work factors in the aetiology of dementia. As an alternative explanation, people might have chosen jobs with poor work factors due to preclinical dementia, which becomes clinically manifest decades later.

Effects of arousing emotional scenes on the distribution of visuospatial attention: changes with aging and early subcortical vascular dementia

BACKGROUND

The modulation of attention by emotionally arousing stimuli is highly important for each individual's social function. Disturbances of emotional processing are a supportive feature for the diagnosis of subcortical vascular dementia (SVD). We address here whether these disturbances might be useful as an early disease marker.

METHODS

In order to examine the modulation of visual attention by emotionally arousing stimuli of different valence, 12 elderly patients with early SVD, 12 age-comparable healthy adults and 12 young healthy subjects were studied while looking at pairs of pictures from the International Affective Picture Battery that were either neutral-neutral, neutral-positive or neutral-negative in terms of emotional content. Eye movements were recorded with an infrared eye-tracking system. The direction of the first saccade and the dwell time during the 10 s of presentation were measured and compared among groups with parametric tests.

RESULTS

All subjects showed a modulation of initial attentional orienting as well as a higher percentage of dwell time towards the pictures containing emotional material. Patients with SVD and old controls did not differ in either experimental measure. Young patients showed a stronger bias towards emotionally negative material than both groups of older individuals.

CONCLUSIONS

Modulation of visuospatial attention is preserved in early SVD. This might have implications for therapeutic interventional approaches. A weakened sustained attention towards negative but not positive emotional pictures in the elderly is in accordance with the socioemotional selectivity theory, describing a relative selection of positive stimuli with aging.

[The effect of psychosocial factors on risk of dementia]

In the etiology of dementia several genetic and various environmental factors are assumed to interact. Most epidemiological studies on risk factors have focused on "constitutional" factors like age, sex, birth order, dementia in the family and "life style" factors like smoking and alcohol consumption. Only few studies have investigated the role of psychosocial factors at work and during leisure time on the risk to develop dementia. Our paper gives a systematic review of all published results of controlled studies about psychosocial risk factors. A positive association has been observed between dementia and living alone, having no close social ties, not participating in social and leisure activities, and never having married. Recent studies have found that Alzheimer's disease in particular is negatively associated with diversity of activities and intensity of intellectual activities and positively associated with psychosocial inactivity, unproductive working style, living with a dominant spouse and with physical inactivity.

[Effect of daily living-related cognitive training on attention and memory performance of persons with dementia]

There are few results of controlled studies about psychological interventions, i.e. training of cognitive functions in dementing illnesses. Most frequently very specific memory strategies are trained, (the effects of) which cannot be generalized to activities of daily living. Thus, a memory training program was developed considering the different cognitive abilities of the participants and which was meant to be generalized to daily tasks. Short-term and long-term memory were trained as well as activities of daily living in 12 lessons for a period of 6 weeks. We can show significant improvements of attention and memory performance in our experimental group in comparison to the control group.

The effects of medical group practice and physician payment methods on costs of care

OBJECTIVE

To assess the effects of payment methods on the costs of care in medical group practices.

DATA SOURCES

Eighty-six clinics providing services for a Blue Cross managed care program during 1995. The clinics were analyzed to determine the relationship between payment methods and cost of care. Cost and patient data were obtained from Blue Cross records, and medical group practice clinic data were obtained by a survey of those organizations.

STUDY DESIGN

The effects of clinic and physician payment methods on per member per year (PMPY) adjusted patient costs are evaluated using a two-stage regression model. Patient costs are adjusted for differences in payment schedules; patient age, gender, and ACG; clinic organizational variables are included as explanatory variables.

DATA COLLECTION

Patient cost data were extracted from Blue Cross claims files, and patient and physician data from their enrollee and provider data banks. Medical group practice data were obtained by a mailed survey with telephone follow-up.

PRINCIPAL FINDINGS

Capitation payment is correlated with lower patient care costs. When combined with fee-for-service with withhold provisions, this effect is smaller indicating that these two clinic payment methods are not interchangeable. Clinics with more physician compensation based on measures of resource use or based on some share of the net revenue of the clinic have lower patient care costs than those with more compensation related to productivity or based on salary. Salary compensation is strongly associated with higher costs. The use of physician profiles and clinical guidelines is associated with lower costs, but referral management systems have no such effect. The lower cost clinics are the smaller, multispecialty clinics.

CONCLUSIONS

This study indicates that payment methods at both the medical group practice and physician levels influence the cost of care. However, the methods by which that influence is manifest is not clear. Although the organizational structure of clinics and their use of managed care programs appear to play a role, this influence is less than expected.

The organizational structure of medical group practices in a managed care environment

This article analyzes the organizational structures of 155 medical group practices providing services in the highly competitive managed care environment in the upper midwest. The structure of the group practices and the methods of physicians' payment are analyzed in terms of the proportion of revenue obtained from financial risk-sharing managed care payment systems and the length of time involved with those systems.