Toward More Selective Antibiotic Inhibitors: A Structural View of the Complexed Binding Pocket of E. coli Peptide Deformylase

Peptide deformylase (PDF) is involved in bacterial protein maturation processes. Originating from the interest in a new antibiotic, tremendous effort was put into the refinement of PDF inhibitors (PDFIs) and their selectivity. We obtained a full NMR backbone assignment the emergent additional protein backbone resonances of ecPDF 1-147 in complex with 2-(5-bromo-1H-indol-3-yl)-N-hydroxyacetamide (2), a potential new structural scaffold for more selective PDFIs. We also determined the complex crystal structures of E. coli PDF (ecPDF fl) and 2. Our structure suggests an alternative ligand conformation within the protein, a possible starting point for further selectivity optimization. The orientation of the second ligand conformation in the crystal structure points toward a small region of the S1' pocket, which differs between bacterial PDFs and human PDF. Moreover, we analyzed the binding mode of 2 via NMR TITAN line shape analysis, revealing an induced fit mechanism.

Structural Insights into Antibacterial Payload Release from Gold Nanoparticles Bound to E. coli Peptide Deformylase

The lack of new antibiotics and the rapidly rising number of pathogens resistant to antibiotics pose a serious problem to mankind. In bacteria, the cell membrane provides the first line of defence to antibiotics by preventing them from reaching their molecular target. To overcome this entrance barrier, it has been suggested[1] that small Gold-Nanoparticles (AuNP) could possibly function as drug delivery systems for antibiotic ligands. Using actinonin-based ligands, we provide here proof-of-principle of AuNP functionalisation, the capability to bind and inhibit the target protein of the ligand, and the possibility to selectively release the antimicrobial payload. To this end, we successfully synthesised AuNP coated with thio-functionalised actinonin and a derivative. Interactions between 15N-enriched His-peptide deformylase 1-147 from E. coli (His-ecPDF 1-147) and compound-coated AuNP were investigated via 2D 1H-15N-HSQC NMR spectra proving the direct binding to His-ecPDF 1-147. More importantly by adding dithiothreitol (DTT), we show that the derivative is successfully released from AuNPs while still bound to His-ecPDF 1-147. Our findings indicate that AuNP-conjugated ligands can address and bind intracellular target proteins. The system introduced here presents a new delivery platform for antibiotics and allows for the easy optimisation of ligand coated AuNPs.

Beyond a blunted ERN - Biobehavioral correlates of performance monitoring in schizophrenia

Cognitive deficits are well documented in schizophrenia. Here, we reviewed alterations in performance monitoring as potential marker of cognitive deficits in schizophrenia. We found that performance monitoring alterations in schizophrenia are specific to early (indexed by blunted error-related negativity (ERN)) and late (reflected in blunted error positivity (Pe)) internal error processing, while external performance feedback processing in simple response feedback tasks is relatively preserved. We propose, that these performance monitoring deficits may best be interpret as one aspect of disrupted theta band (4-8 Hz) oscillations over medial frontal recordings sites. Midfrontal theta dynamics are an increasingly established direct neural index of the recruitment of cognitive control and are impaired in several clinical populations. While theta-related ERPs (the ERN) may be an easy to assess marker of cognitive deficits in schizophrenia, further work investigating the trial-by-trial dynamics of theta in both the time and time-frequency domain is needed to parse cognitive deficits in schizophrenia into finer levels of detail and evaluate theta modulation as a therapeutic tool.

Akinetic mutism caused by bilateral infiltration of the fornix in a patient with astrocytoma

In a 59-year-old female patient, a World Health Organization (WHO) grade II astrocytoma had been diagnosed 16 years ago, which finally progressed into WHO grade III. Several right frontal neurosurgical resections, local radiation and a local radioimplant had been applied. Despite this long record, she was reported alert with a Karnofsky index of 90% until admission. Within a few weeks she rapidly developed akinetic mutism. Upon admission, computed tomography (CT) scan showed a large cystic right frontal defect and a suggested small tumor recurrence. White matter of the frontal lobe appeared to be translucent and compatible with previous radiation. The severe mental changes were initially attributed to a delayed radiation encephalopathy. Neuropathologically, the white matter of the frontal lobe showed mild elevated cell density consistent with gliosis; however, a tumor recurrence invading the tip of the corpus callosum and invading the entire length both fornices appeared. From the neuropathological findings of massive local tumor recurrence in both fornices, together with the acute clinical onset, it seems unlikely that the sequel of radiotherapy caused akinetic mutism, but the symmetric and severe involvement of the limbic system. We conclude that the rapid progression from a state of alertness to a full clinical picture of akinetic mutism was because of infiltration of both fornices.

Auto-alloplastic transplantation of a primary canine after traumatic loss of a permanent central incisor

This report describes the transplantation of a primary canine after traumatic loss of a central incisor in an 8-year-old boy. The 7-month follow-up revealed normal periodontal healing with absence of infection, ankylosis or progressive resorption. The patient was then lost for control. After 16 months another trauma in the same patient resulted in an avulsion of the transplant. However, the alveolar bone was maintained in vertical and sagittal dimensions. Another primary canine was transplanted and followed for further 11 months. Again normal periodontal healing could be observed. The transplantation of a primary canine is seen as a promising method to replace a lost permanent tooth and maintain the surrounding tissues in very young patients.

Anatomy of the porta hepatis as a basis for extended hepatoporto-enterostomy for extrahepatic biliary atresia--a new surgical technique

Reports on long-term survival rates after Kasai's HPE reveal that 23% of patients are healthy ten and more years after surgery. Therefore we studied again the anatomy and histology of the porta hepatis and the portal tracts in order to improve this surgical procedure.

METHODS

Autopsied livers of 6 children with and 6 without EHBA were investigated with regard to the topographical and histological anatomy of the major intra- and extrahepatic bile ducts.

RESULTS

On the basis of anatomical findings we have modified the conventional Kasai's HPE and developed an extended exploration of the porta hepatis. The procedure and surgical technique is described in this paper.

Periodontal healing after intentional auto-alloplastic reimplantation of injured immature upper front teeth

BACKGROUND/AIMS

Conventional endodontic treatment results in high complication quota when performed in immature teeth. Intentional reimplantation with extraoral insertion of an endodontic implant (auto-alloplastic reimplantation) is an alternative.

METHOD

In a retrospective study, the healing of 40 teeth reimplanted intentionally according to this method in patients aged 7 to 15 years was evaluated. Clinical tests (palpation, percussion sound, periotest values) and radiographical examinations were used to determine the type of periodontal healing (inflammatory resorption/periodontitis apicalis; replacement resorption/ankylosis; normal healing).

RESULTS

Mean lifetime of the replanted teeth was 59.2+/-42.5 months, estimated survival time on the basis of the Kaplan-Meier analysis was 99.5 months. 17 teeth (42.5%) were classified as failures, mostly due to inflammatory resorption or periodontitis apicalis. Further investigations demonstrated that success rate and retention period of intentionally replanted teeth depend on the preoperative condition of the pulp. Teeth with preoperative infection suffered frequently from inflammatory resorption or periodontitis apicalis after being replanted (14 of 28 teeth). Estimated survival time according to Kaplan-Meier was 75.5 months. In contrast, inflammations or progressive resorptions were not observed in teeth without preoperative infection of the pulp. All these 12 teeth showed normal periodontal healing and regular tooth mobility. In the absence of any pathology in clinical or radiological findings after an average functional period of 72.3 months, the prognosis can be presumed excellent. Estimated survival time of 148.3 months according to Kaplan-Meier differs significantly from survival time of teeth infected preoperatively.

CONCLUSIONS

From the results of this investigation, it may be concluded that an infection of the pulp - due to delay of treatment or attempts at endodontic therapy - should be avoided before intentional replantation of immature front teeth with pulp necrosis. Periodontal healing of the autologous root is not impaired by the insertion of posts made of Al2O3-ceramics or titanium. The inserted posts do not ankylose. Orthodontic movement of auto-alloplastically replanted teeth is possible.

[Cytokeratin and p53 expression of odontogenic cysts]

The histopathologic diagnosis of odontogenic cysts is based mainly on the morphological nature of the epithelial lining of cysts and their origin. We used the international histologic classification set up by the World Health Organisation in 1992. The aim of this study was to investigate the differentiation of various types of cyst using an immunohistochemical technique rather than by conventional morphological assessment. A standard immunocytochemical method (APAAP method), applying anticytokeratin monoclonal antibodies and a p53 antibody, was used for the diagnosis of odontogenic cysts. A total of 57 jaw cysts were diagnosed according to clinical, radiological and pathological criteria as radicular cysts (20), dentigerous cysts (20) and keratocysts (17). The results proved that cyst type can be distinguished by the pattern of staining using the monoclonal antibodies CK7, CK19, CK20 for cytokeratins and the clone DO-7 for the p53 protein. Staining with the monoclonal antibodies CK7 and CK20 did not distinguish type. CK19 was not detected in keratocysts and p53 was only expressed in keratocysts. This may prove to be diagnostically useful for the more precise distinction between different cyst types.

Investigations on a cell culture medium for storage and transportation of avulsed teeth

Non-physiologic storage of avulsed teeth leads to a high incidence of root resorption, resulting in poor prognosis. This study investigated the suitability of specially composed cell culture media for storage of extracted teeth for up to 48 hours. Autoradiographic investigations revealed that the proliferative activity of periodontal ligament (PDL) cells of teeth stored in cell culture medium for up to 48 hours increased with storage time. Studies on proliferation of PDL cells after storage of teeth in different media for up to 24 hours demonstrated that the proliferative activity is dependent on the composition of the medium. Immunohistochemical investigations with markers for cell proliferation revealed that pulp cells of extracted immature teeth show numerous proliferations after storage for up to 24 hours in a special cell culture medium but few proliferations after storage in Hanks Balanced Salt Solution (HBSS). The investigations indicate that a special cell culture medium can preserve cell viability of PDL cells adhering to extracted teeth for at least 48 hours. The in vitro results are confirmed by a case presented: After storage of two upper central incisors for 36 hours in the cell culture medium the teeth could be successfully reimplanted after extraoral insertion of titanium posts into the root canal (auto-alloplastic reimplantation). Clinical and radiological follow-up examinations for 12 months revealed normal periodontal healing.

Replantation of avulsed primary anterior teeth: treatment and limitations

In addition to the successful replantation of avulsed permanent teeth, the replantation of primary anterior teeth may also be indicated. The decision is based on age and stage of tooth development, development of dentition, storage of the avulsed tooth and the way it is transported to the treatment site, the appropriate in vitro treatment of the tooth before reinsertion, and the willingness of the child to cooperate. A method involving retrograde filling of the primary tooth root with calcium hydroxide after resecting the root apex has proved successful. Other commercially available root filling materials and pins are not indicated. Calcium hydroxide allows the tooth to heal in place without reaction and prevents the development of apical periodontitis. As regards any surgical intervention, the attending dentist in this case has to weigh the benefits against the risks.

Dental treatment of handicapped patients using endotracheal anesthesia

Dental treatment using endotracheal anesthesia is indicated where acute odontogenic infections, accidental injuries, or multiple caries and periodontitis marginalis require surgical and/or restorative treatment. It is also indicated where it is not possible to use psychological support during local anesthesia or during premedication or analgosedation. Dental treatment of handicapped patients using endotracheal anesthesia is described, along with indication and frequency of such treatment. The state of the dentition is illustrated, along with its relationship to the oral hygiene the handicapped patients receive. The main points of the intraoperative dental procedures and the follow-up of patient care are reported. Postoperative dental or general medical complications have not occurred within the patient population under study.

Social and environmental factors in lung cancer mortality in post-war Poland

Poland and other Eastern European countries have undergone heavy industrial development with marked increases in air pollution and occupational exposure in the nearly 50 years since World War II. These countries have also experienced substantial increases in chronic disease mortality in the past three decades. While it is tempting to assume a direct association between these phenomena, more detailed analyses are called for. Poland offers a potentially rich opportunity for comparing geographical patterns of disease incidence and of industrial change. In this paper we 1) elucidate the prospects for attributing lung cancer mortality to industrial emissions in Poland, using an ecological approach based on the hitherto unaddressed geographic differences, and accounting for regional differences in cigarette consumption; 2) propose explanatory hypotheses for the observed geographic heterogeneity of lung cancer; 3) begin systematic testing of the widely accepted but not well-scrutinized notion that pollution in Poland is a major contributor to declining life expectancy. Regions with the highest fraction of cancer that cannot be explained by smoking appear to be highly urbanized, have high population exposure to occupational carcinogens, experience the highest rates of alcoholism and crime, and are associated with the post- World War II population resettlement. Although the analysis does not rule out pollution as a significant contributor to lung cancer mortality, it indicates that other factors such as occupational exposures and various social factors are of at least comparable importance.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical and radiation physics studies on the influence of mandibular reconstruction plates on the dose distribution of ultrahard photons]

The effect of mandibular reconstruction plates on the dose distribution of megavoltage photons was analysed. All treated patients showed the normal reactions expected from radiation therapy regardless the modification of dose distribution by the metal plates. For dose estimation measurements were done in a phantom with photons of the energy 60Co to 42 MV and different material.

[Aluminum, steel and tungsten portal film cassettes for the imaging verification of 60Co photon irradiation up to 42 MV in a clinical trial]

The movement of the patient lowers the contrast of the portals, because the exposition time is long and identical with the treatment time. To enhance the contrast in the portals, the first models of the cassettes were modified under the clinical tests by a rear sheet nearly free from backscattering. With the modified cassettes iodine contrast media are weakly seen on the portals in the laboratory tests, but not in the clinical routine.

[Water disinfection of dental treatment units using ozone]

The disinfecting effect of ozonized water has been investigated. Under the precondition that the dental chair had been thoroughly sanitized, the system showed a good disinfecting effect. Finally, for reasons of practical medical treatment, the ozone concentration in air and, for reasons of hygiene in drinking water, the ozone concentrations in water were determined under various conditions. In addition, the influence of continuous-flow water heaters is discussed. The problem of continuous-flow water heaters regarding their effects on the colonisation of water by microbes proves not to be significant. The exposure of patients to disinfectants is discussed.

[A new system for cervix application using the afterloading technique]

We developed a new application system for the intracavitary afterloading therapy of the cervix carcinoma. With this system special problems of the application as the possible perforation of the cervix uteri are prevented.

[Radiotherapeutic quality assurance in the Hodgkin's disease study HD4 supported by the BMFT (Bundesministerium für Forschung und Technologie)]

In the German Hodgkin Study Group a radiotherapy assurance program is being carried out at the radiotherapeutic reference centre in Göttingen since April 1988: 74 patients were entered from 27 radiotherapeutic institutions. 18 of them participated in a quality assurance program and submitted the data of 29 patients: In 21 of the 29 patients the protocol was followed correctly. Physical aspects of quality control showed two major deviations from the protocol: one center used photon energies of more than 15 MVX without mould; another had a anterior-posterior loading of 3:1. The radiation oncology assessment detected six inadequate treatments: The safety margin was inappropriate in three of 26 mantle fields. Another center used a multiple field technique, and in two patients the paraaortic region was not irradiated.

[Experimental studies on the possible use of single- and multi-layer absorbers to form irregular electron fields]

The relative dose is investigated behind homogeneous and composed absorbers of electrons. As a result of the measurements the homogeneous absorbers made of heavy metals were preferred to form irregular fields in electron therapy.