Traumatic lumbar disc herniation: A systemic case review and meta-analysis

Introduction

Traumatic lumbar disc herniation (TLDH) without fracture in the in-situ motion segment is a rare occurrence compared with degenerative herniation.

Research question

This study provides a systematic discussion of various aspects related to the diagnosis of TLDH.

Material and methods

This review includes 12 cases of TLDH with MR-images since 2009 published in the PubMed and one adjunct illustration. The cases were categorized into two groups for a comprehensive analysis, TLDH with or without in-situ segment fracture. Additionally, we reported a case of a 43-year-old female patient with a recent stenosing TLDH at L5/S1, accompanied by a large sequestration (disc herniation stage-4, and Michigan State University Classification: MSU 3-AB) and an endplate compression fracture at L2 (AO A1).

Results

Isolated traumatic lumbar disc herniation is possible, but it is required exclude cases with fractures in the in-situ motion segment.

Discussion and conclusion

Trauma with related injury mechanisms is the highest priority for the diagnosis of TLDH. Low-grade disc degeneration without significant instability could be accepted for diagnosing TLDH. A TLDH on MR images might show a slightly lower T2-signal compared to the CSF and a homogeneous T1-signal like the spinal cord, as well as a similar STIR-signal of the sequestration and CSF. If necessary, a histological examination could be performed to evaluate the degenerative changes in the injured disc, especially to assist the evaluation due to legal reasons.

Notch signaling drives development of Barrett's metaplasia from Dclk1-positive epithelial tuft cells in the murine gastric mucosa

Barrett's esophagus (BE) is a precursor to esophageal adenocarcinoma (EAC), but its cellular origin and mechanism of neoplastic progression remain unresolved. Notch signaling, which plays a key role in regulating intestinal stem cell maintenance, has been implicated in a number of cancers. The kinase Dclk1 labels epithelial post-mitotic tuft cells at the squamo-columnar junction (SCJ), and has also been proposed to contribute to epithelial tumor growth. Here, we find that genetic activation of intracellular Notch signaling in epithelial Dclk1-positive tuft cells resulted in the accelerated development of metaplasia and dysplasia in a mouse model of BE (pL2.Dclk1.N2IC mice). In contrast, genetic ablation of Notch receptor 2 in Dclk1-positive cells delayed BE progression (pL2.Dclk1.N2fl mice), and led to increased secretory cell differentiation. The accelerated BE progression in pL2.Dclk1.N2IC mice correlated with changes to the transcriptomic landscape, most notably for the activation of oncogenic, proliferative pathways in BE tissues, in contrast to upregulated Wnt signalling in pL2.Dclk1.N2fl mice. Collectively, our data show that Notch activation in Dclk1-positive tuft cells in the gastric cardia can contribute to BE development.

Notch Signaling Mediates Differentiation in Barrett's Esophagus and Promotes Progression to Adenocarcinoma

BACKGROUND & AIMS

Studies are needed to determine the mechanism by which Barrett's esophagus (BE) progresses to esophageal adenocarcinoma (EAC). Notch signaling maintains stem cells in the gastrointestinal tract and is dysregulated during carcinogenesis. We explored the relationship between Notch signaling and goblet cell maturation, a feature of BE, during EAC pathogenesis.

METHODS

We measured goblet cell density and levels of Notch messenger RNAs in BE tissues from 164 patients, with and without dysplasia or EAC, enrolled in a multicenter study. We analyzed the effects of conditional expression of an activated form of NOTCH2 (pL2.Lgr5.N2IC), conditional deletion of NOTCH2 (pL2.Lgr5.N2fl/fl), or loss of nuclear factor κB (NF-κB) (pL2.Lgr5.p65fl/fl), in Lgr5+ (progenitor) cells in L2-IL1B mice (which overexpress interleukin 1 beta in esophagus and squamous forestomach and are used as a model of BE). We collected esophageal and stomach tissues and performed histology, immunohistochemistry, flow cytometry, transcriptome, and real-time polymerase chain reaction analyses. Cardia and forestomach tissues from mice were cultured as organoids and incubated with inhibitors of Notch or NF-kB.

RESULTS

Progression of BE to EAC was associated with a significant reduction in goblet cell density comparing nondysplastic regions of tissues from patients; there was an inverse correlation between goblet cell density and levels of NOTCH3 and JAG2 messenger RNA. In mice, expression of the activated intracellular form of NOTCH2 in Lgr5+ cells reduced goblet-like cell maturation, increased crypt fission, and accelerated the development of tumors in the squamocolumnar junction. Mice with deletion of NOTCH2 from Lgr5+ cells had increased maturation of goblet-like cells, reduced crypt fission, and developed fewer tumors. Esophageal tissues from in pL2.Lgr5.N2IC mice had increased levels of RelA (which encodes the p65 unit of NF-κB) compared to tissues from L2-IL1B mice, and we found evidence of increased NF-κB activity in Lgr5+ cells. Esophageal tissues from pL2.Lgr5.p65fl/fl mice had lower inflammation and metaplasia scores than pL2.Lgr5.N2IC mice. In organoids derived from pL2-IL1B mice, the NF-κB inhibitor JSH-23 reduced cell survival and proliferation.

CONCLUSIONS

Notch signaling contributes to activation of NF-κB and regulates differentiation of gastric cardia progenitor cells in a mouse model of BE. In human esophageal tissues, progression of BE to EAC was associated with reduced goblet cell density and increased levels of Notch expression. Strategies to block this pathway might be developed to prevent EAC in patients with BE.

Gender associated developmental trajectories of SDQ-dysregulation profile and its predictors in children

BACKGROUND

Severe mood dysregulation is common in childhood and can be highly impairing. The Dysregulation Profile (DP) can be considered as a broader phenotype of emotional dysregulation, including affect, cognition and behaviour. Since mood dysregulation may persist, but differently in boys and girls, the gender associated course needs to be considered longitudinally to gain a better insight in order to support the children more adequately. This study is focusing on gender associated subgroup trajectories of the Strengths and Difficulties Questionnaire-Dysregulation Profile (SDQ-DP) in middle childhood (9-13 years of age) and includes the potential impact of clinical and psychosocial characteristics.

METHOD

The data set was available from the BELLA study on mental health and well-being in children and adolescents, which is the mental health module of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). A representative epidemiological sample of 564 children living in Germany was examined at three assessment points over 2 years (data collection 2003-2006). The SDQ-DP of children aged 9-13 years was evaluated using Latent Class Growth Analysis (LCGA).

RESULTS

For both genders three trajectories with low (girls 67.0% and boys 59.5%), moderate (girls 28.0% and boys 31.7%) and high SDQ-DP (girls 5.0% and boys 8.8%) scores were detected. The courses of low and moderate subgroups were stable, while in the high SDQ-DP subgroup boys showed a decreasing and girls an increasing trend in symptom severity on a descriptive level. The results of the multinomial logistic regression analyses revealed a significant influence of mainly externalising but also internalising problems both increasing the risk of moderate and high SDQ-DP in both genders. Good quality of life was a protective factor for the SDQ-DP course in all subgroups.

CONCLUSION

In addition to the known clinical and scientific value of the SDQ-DP, three distinguishable trajectories of SDQ-DP in boys and girls could be found. High externalising problems at the beginning of the trajectory were associated with an undesirable course of SDQ-DP. These findings might be helpful for better psychoeducation, counselling and monitoring in clinical cases and public health.

Three New Potent HIV-1 Inhibitors from Myxobacteria

Three novel compounds, namely, phenoxan, phenalamide A1, and thiangazole, were found to suppress HIV-1 replication in cell cultures. The compounds were discovered by screening crude extracts from myxobacteria and were isolated from two strains of Polyangium sp. and a strain of Myxococcus stipitatus. Their structures have been elucidated. The cytotoxic concentrations for MT-4 cells were 6.6 μM for phenoxan, 102 μM for phenalamide A1, and 4.7 μM for thiangazole. Phenoxan inhibited the HIV-1-dependent cell death at concentrations of as low as 6.6 nM. Phenalamide A1 could prevent the HIV-1 infection of MT-4 cells even at concentrations of 1.02nM, and thiangazole at 4.7 pM. In our assay thiangazole is at least 100 times more active than AZT. The compounds could not prevent syncythia formation induced by HIV-1. However, like HEPT (Baba et al., 1989; Miyasaka et al., 1989) and TIBO (Pauwels et al., 1990) derivatives they are highly specific since they could not interfere with HIV-2ben dependent MT-4 cell death. HIV-1 RT activity was inhibited by 50% by 376 μM phenoxan, 386 μM phenalamid A1, or 263 μM thiangazole. Since these concentrations are approximately 50000 times higher than their minimum concentrations active in cell cultures, RT-inhibition does not appear to be the major mechanism of HIV-inhibition of the new agents.

Clear-cell sarcoma of the soft tissue--a rare diagnosis with a fatal outcome

Clear-cell sarcomas account for less than 1% of all soft tissue tumours. They most often occur in middle-aged adults as a deeply located lesion with predilection to the tendons and aponeuroses. The aim of the present study was to show possible influencing factors on the outcome after surgical treatment in a detailed case series. We reviewed the medical records of 11 patients with the diagnosis of a clear-cell sarcoma of the soft tissue. These cases were analysed with regard to age, gender, localisation, tumour size, recurrence free survival and overall survival. A minimum follow up of 12 months was achieved. The mean age at the point of diagnosis was 47.9 years. Metastases occurred after a mean of 19.2 months. In the cases with a tumour diameter >5 cm, metastases occurred earlier. When treated in a specialist centre, metastases occurred later. Patients died a mean of 18.4 months after developing metastatic disease. Patients with tumour size >5 cm at the point of primary diagnosis died earlier than patients with a tumour size <5 cm. It is important to detect clear-cell sarcomas as soon as possible and the final surgical treatment should be performed in a centre familiar with the treatment of soft tissue tumours not only to prolong overall survival, but also to treat the patient in a multiprofessional team.

Myositis proliferans: diagnosis and therapy of a pseudosarcomatous soft tissue lesion

Myositis proliferans is a soft tissue neoplasia with rare incidence. In the most cases, it is localized in the region of the neck, shoulder, pelvis and thigh. Due to its rapid growth and histological picture, the tumour may appear as a malignant neoplasia. We report the case of a 29-year-old woman suffering from an increasing painful swelling of the left proximal lower leg. Performed biopsies and histological examinations provided the diagnosis of myositis proliferans adjacent to the fibula, which responded to local resection and did not recur after 2 years. We show the importance of adequate diagnostic and therapeutic approach to avoid unnecessary and probably radical overtherapy of the patient.

[Posterior and transforaminal lumbar interbody fusion (PLIF/TLIF) for the treatment of localised segment degeneration of lumbar spine]

BACKGROUND

Chronic intractable low back pain is one of the most common orthopaedic diagnoses, with an enormous socioeconomic impact. The surgical treatment by posterior transpedicular instrumentation and interbody fusion of the affected segments is an established procedure after exhaustion of conservative therapies. Due to different study data on the clinical and functional results after posterior (PLIF) and transforaminal (TLIF) interbody fusion, our own patient population was analysed retrospectively.

PATIENTS AND METHODS

Included were 143 patients who had been treated surgically at our institution between 1999 and 2006 by one of the two methods (PLIF, n = 68; TLIF, n = 75). In addition to general demographic data, results of three questionnaires (Oswestry disability index, numeric rating scale, Roland Morris score) were retrospectively analysed before surgery and in the general follow-up - identifying clinical and functional results of patient satisfaction.

RESULTS

All patients had been suffering in spite of the exhaustion of conservative therapies for at least six months of chronic low back pain prior to surgery. The mean age at surgery was 52 years. The complication rate was 23 %, the revision rate 15 %. Overall, there was a high patient satisfaction in follow-up. In ODI, a significant decrease in pain-related disability was observed from 49.8 % preoperatively to 24.7 % after surgery (p < 0.0001). This functional improvement was present in all aetiological subgroups irrespective of the fusion length. A statistically significantly better functional outcome was achieved in the ODI in the PLIF group (improvement 27.2 % vs. 23.1 %, p < 0.0001). The preoperative baseline regarding pain was assessed in the NRS on average at 6.5 points. Postoperatively, it decreased to 3.34 points (p < 0.0001). The functional limitation due to existing back pain was assessed preoperatively with an average of 13.08 points. Postoperatively a significant reduction to 6.19 points was observed (p < 0.0001). Group- or operation-specific differences were not statistically significant.

CONCLUSION

The data of this study indicate that both TLIF and PLIF techniques are possible surgical treatment methods for patients with resistant chronic low back pain. With both techniques a clear benefit regarding quality of life and function for the operated patients is achievable, if the correct surgical indication is given.

In vitro reconstitution of the myxochelin biosynthetic machinery of Stigmatella aurantiaca Sg a15: Biochemical characterization of a reductive release mechanism from nonribosomal peptide synthetases

Microorganisms produce iron-chelating compounds to sequester the iron essential for growth from the environment. Many of these compounds are biosynthesized by nonribosomal peptide synthetases, some in cooperation with polyketide synthases. Myxochelins are produced by the myxobacterium Stigmatella aurantiaca Sg a15, and the corresponding gene cluster was cloned recently. We have undertaken to express heterologously the myxochelin biosynthetic machinery in Escherichia coli. To activate the involved proteins posttranslationally, they were coexpressed with the phosphopantetheinyltransferase MtaA from the myxothiazol biosynthetic gene cluster. Phosphopantetheinylation of the carrier proteins could be verified by protein mass analysis. Six active domains in proteins MxcE, MxcF, and MxcG are capable of assembling myxochelin from ATP, NAD(P)H, lysine, and 2,3-dihydroxybenzoic acid in vitro. This fact demonstrates that the condensation domain of MxcG performs two condensation reactions, creating the aryl-capped alpha-amide and the aryl-capped gamma-amide of the molecule. A previously unknown type of reductive release is performed by the reduction domain of MxcG, which alternatively uses NADPH and NADH to set free the peptidyl-carrier protein-bound thioester as an aldehyde and further reduces it to the alcohol structure that can be found in myxochelin A. This type of reductive release seems to be a general mechanism in polyketide and nonribosomal peptide biosynthesis, because several systems with C-terminal similarity to the reductase domain of MxcG can be found in the databases. Alternatively, the aldehyde can be transaminated, giving rise to a terminal amine.

Multiple hybrid polyketide synthase/non-ribosomal peptide synthetase gene clusters in the myxobacterium Stigmatella aurantiaca

Many bacterial and fungal secondary metabolites are produced by polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS). Recently, it has been discovered that these modular enzymatic systems can also closely cooperate to form natural products. The analysis of the corresponding biosynthetic machineries, in the form of hybrid systems, is of special interest for combinatorial biosynthesis, because the combination of PKS and NRPS can lead to an immense variety of structures that might be produced. During our screening for hybrid PKS/NRPS systems from myxobacteria, we scanned the genome of Stigmatella aurantiaca DW4/3-1 for the presence of gene loci that encode both the PKS and NRPS genes. In addition to the previously characterized myxothiazol system, we identified three further hybrid loci, three additional PKS and one further NRPS gene locus. These were analyzed by hybridization, physical mapping, PCR with degenerate oligonucleotides and sequencing of fragments of the gene clusters. The function of these genes was not known but it had already been speculated that one compound produced by the strain and detected via HPLC was a secondary metabolite. This was based on the observation that its production is dependent on an active copy of the phosphopantetheinyl transferase gene mtaA. We show here that one of the identified hybrid gene loci is responsible for the formation of this secondary metabolite. In agreement with the genetic data, the chemical structure resembles a cyclic polypeptide with a PKS sidechain. Our data show that S. aurantiaca has a broader genetic capacity to produce natural products than the number of compounds isolated from the strain so far suggests.

Source and component genes of a 6-200 Mb gene cluster in the house mouse

We identified and analyzed the genes Sp100, Csprs, and Ifi75 in two members of the genus Mus, M. musculus and M. caroli. Sp100 is a nuclear dot gene; Csprs and Ifi75 are novel genes encoding a putative G-protein coupled receptor (GPCR) and a putative transcriptional coactivator, respectively. A fourth gene, Sp100-rs, occurs in M. musculus, but not in M. caroli. Sp100-rs is a chimeric gene which arose by fusion of Sp100 and Csprs copies. Sp100-rs and Ifi75 are components of a repeat cluster that extends over 6-200 Mb of the M. musculus genome. The Sp100-rs fusion gene arose only 1-2 million years ago and has become fixed and amplified in M. musculus. Although the gene is transcribed, it appears to have no function. The repeat cluster may have become fixed in the species as a 'hitchhiker' in a 'selective sweep'.

Evolution of a 6-200 Mb long-range repeat cluster in the genus Mus

By fluorescence in situ hybridization, we mapped the location of genes associated with the Sp100-rs cluster, a long-range repeat cluster in chromosome 1 of the house mouse, Mus musculus. The cluster comprises between 60 and 2000 repeats and extends over 6-200 Mb of the M. musculus genome, depending on the source of the cluster. The cluster evolved during the last two million years in the genus Mus in the lineage to which M. musculus belongs. The Asiatic mouse species M. caroli is not in this lineage and does not possess the cluster. M. caroli represents the ancestral genomic organization of the cluster source components Sp100, Csprs and Ifi75: they are located close to each other in the same chromosome band (1D). However, Sp100-rs, the principal gene of the cluster, is not present in the M. caroli genome. It is a chimeric M. musculus gene that arose by fusion of Csprs and the 5' part of Sp100. Sp100-rs and Ifi75 are homogeneously distributed throughout the cluster while Sp100 and Csprs in its original sequence context flank the cluster on opposite sides. Our results suggest a model for the origin and evolution of the long-range repeat cluster by duplication, gene fusion and amplification.

Novel features in a combined polyketide synthase/non-ribosomal peptide synthetase: the myxalamid biosynthetic gene cluster of the myxobacterium Stigmatella aurantiaca Sga15

BACKGROUND

Myxobacteria have been well established as a potent source for natural products with biological activity. They produce a considerable variety of compounds which represent typical polyketide structures with incorporated amino acids (e.g. the epothilons, the myxothiazols and the myxalamids). Several of these secondary metabolites are effective inhibitors of the electron transport via the respiratory chain and have been widely used. Molecular cloning and characterization of the genes governing the biosynthesis of these structures is of considerable interest, because such information adds to the limited knowledge as to how polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs) interact and how they might be manipulated in order to form novel antibiotics.

RESULTS

A DNA region of approximately 50000 base pairs from Stigmatella aurantiaca Sga15 was sequenced and shown by gene disruption to be involved in myxalamid biosynthesis. Sequence analysis reveals that the myxalamids are formed by a combined PKS/NRPS system. The terminal NRPS MxaA extends the assembled polyketide chain of the myxalamids with alanine. MxaA contains an N-terminal domain with homology to NAD binding proteins, which is responsible during the biogenesis for a novel type of reductive chain release giving rise to the 2-amino-propanol moiety of the myxalamids. The last module of the PKS reveals an unprecedented genetic organization; it is encoded on two genes (mxaB1 and mxaB2), subdividing the domains of one module from each other. A sequence comparison of myxobacterial acyl-transferase domains with known systems from streptomycetes and bacilli reveals that consensus sequences proposed to be specific for methylmalonyl-CoA and malonyl-CoA are not always reliable.

CONCLUSIONS

The complete biosynthetic gene cluster of the myxalamid-type electron transport inhibitor from S. aurantiaca Sga15 has been cloned and analyzed. It represents one of the few examples of combined PKS/NRPS systems, the analysis and manipulation of which has the potential to generate novel hybrid structures via combinatorial biosynthesis (e.g. via module-swapping techniques). Additionally, a new type of reductive release from PKS/NRPS systems is described.

The myxochelin iron transport regulon of the myxobacterium Stigmatella aurantiaca Sg a15

The biosynthetic gene cluster of the myxochelin-type iron chelator was cloned from Stigmatella aurantiaca Sg a15 and characterized. This catecholate siderophore was only known from two other myxobacteria. The biosynthetic genes of 2,3-dihydroxybenzoic acid are located in the cluster (mxcC-mxcF). Two molecules of 2, 3-dihydroxybenzoic acid are activated and condensed with lysine in a unique way by a protein homologous to nonribosomal peptide synthetases (MxcG). Inactivation of mxcG, which encodes an adenylation domain for lysine, results in a myxochelin negative mutant unable to grow under iron-limiting conditions. Growth could be restored by adding Fe3+, myxochelin A or B to the medium. Inactivation of mxcD leads to the same phenotype. A new type of reductive release from nonribosomal peptide synthetases of the 2, 3-dihydroxybenzoic acid bis-amide of lysine from MxcG, catalyzed by a protein domain with homology to NAD(P) binding sites, is discussed. The product of a gene, encoding a protein similar to glutamate-1-semialdehyde 2,1-aminomutases (mxcL), is assumed to transaminate the aldehyde that is proposed as an intermediate. Further genes encoding proteins homologous to typical iron utilization and iron uptake polypeptides are reported.

Stigmatella aurantiaca Sg a15 carries genes encoding type I and type II 3-deoxy-D-arabino-heptulosonate-7-phosphate synthases: involvement of a type II synthase in aurachin biosynthesis

3-Deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthases catalyse the first step of the shikimate pathway. Two unrelated DAHP synthase types have been described in plants and bacteria. Two type II (aroA(A2) and aroA(A5)) and one type I DAHP synthase gene (aroA001) were identified from the myxobacterium Stigmatella aurantiaca Sg a15. Inactivation of aroA(A5) leads to a mutant that is impaired in the biosynthesis of aurachins, which are electron transport inhibitors and contain an anthranilate moiety. Feeding of anthranilic acid to the mutant culture restores production of aurachins. Inactivation of aroA(A2) and aroA001 does not impair production of aurachins or other known secondary metabolites of S. aurantiaca Sg a15.

Transcription and proper splicing of a mammalian gene in yeast

The house mouse strain C57BL/6 harbours 64 copies of the multicopy gene Sp100-rs. Three of these are contained in the yeast artificial chromosome (YAC) clone yMm75. Four Sp100-rs transcripts of 3.0, 2.6, 1.6 and 1.3kb were detected by Northern hybridization in the yMm75-harbouring line of Saccharomyces cerevisiae. Additional and less abundant transcripts were detected by RT-PCR. With one exception, the YAC-derived Sp100-rs transcripts were a subset of those found in the C57BL/6 mouse. This indicates transcription and proper splicing of murine pre-mRNAs in yeast. Analysis of the splice sites shows that the yeast splicing machinery accepts splice sites that deviate from the standard yeast consensus sequences. It may be feasible, therefore, at least in a fair proportion of cases, to exploit the mammalian mRNAs present in transgenic yeast for gene recognition of YAC-inserts.

Silencing of the Y-chromosomal gene tspy during murine evolution

We have studied the process of tspy gene silencing in murine evolution. We have isolated functional tspy sequences from Apodemus agrarius, A. sylvaticus, A. flavicollis, and Mus platythrix (subgenus Pyromys) and nonfunctional tspy sequences from species of the subgenus Mus. We present two alternative models as to how tspy may have lost its function in the murine lineage.

New lessons for combinatorial biosynthesis from myxobacteria. The myxothiazol biosynthetic gene cluster of Stigmatella aurantiaca DW4/3-1

The biosynthetic mta gene cluster responsible for myxothiazol formation from the fruiting body forming myxobacterium Stigmatella aurantiaca DW4/3-1 was sequenced and analyzed. Myxothiazol, an inhibitor of the electron transport via the bc(1)-complex of the respiratory chain, is biosynthesized by a unique combination of several polyketide synthases (PKS) and nonribosomal peptide synthetases (NRPS), which are activated by the 4'-phosphopantetheinyl transferase MtaA. Genomic replacement of a fragment of mtaB and insertion of a kanamycin resistance gene into mtaA both impaired myxothiazol synthesis. Genes mtaC and mtaD encode the enzymes for bis-thiazol(ine) formation and chain extension on one pure NRPS (MtaC) and on a unique combination of PKS and NRPS (MtaD). The genes mtaE and mtaF encode PKSs including peptide fragments with homology to methyltransferases. These methyltransferase modules are assumed to be necessary for the formation of the proposed methoxy- and beta-methoxy-acrylate intermediates of myxothiazol biosynthesis. The last gene of the cluster, mtaG, again resembles a NRPS and provides insight into the mechanism of the formation of the terminal amide of myxothiazol. The carbon backbone of an amino acid added to the myxothiazol-acid is assumed to be removed via an unprecedented module with homology to monooxygenases within MtaG.

Melithiazols, new beta-methoxyacrylate inhibitors of the respiratory chain isolated from myxobacteria. Production, isolation, physico-chemical and biological properties

New antibiotic compounds, melithiazols, were isolated from the culture broth of strains of the myxobacteria Melittangium lichenicola, Archangium gephyra, and Myxococcus stipitatus. The compounds belong to the group of beta-methoxyacrylate (MOA) inhibitors and are related to the myxothiazols. The melithiazols show high antifungal activity, but are less toxic than myxothiazol A and its methyl ester in a growth inhibition assay with mouse cell cultures. The melithiazols inhibit NADH oxidation by submitochondrial particles from beef heart. Melithiazol A blocks the electron transport within the bc1-segment (complex III) and causes a red shift in the reduced spectrum of cytochrome b.

Pericentric satellite DNA and molecular phylogeny in Acomys (Rodentia)

Satellite DNAs (stDNAs) of four Acomys species (spiny-mice), A. cahirinus, A. cineraceus, A. dimidiatus and A. russatus, belong to closely related sequence families. Monomer sizes range from 338 to 364 bp. Between-species sequence identity was from 81.0% to 97.2%. The molecular phylogeny of the sequences helps to clarify the taxonomy of this 'difficult' group. The A. dimidiatus genome contains about 60000 repeats. According to the restriction patterns, repeats are arranged in tandem. The stDNA maps to the centromeric heterochromatin of most autosomes, both acrocentric and metacentric, but appears to be absent in the centromeric region of Y chromosomes. A well-conserved centromere protein B (CENP-B) box is present in the stDNA of A. russatus while it is degenerated in the other species.

Metabolic diversity in myxobacteria: identification of the myxalamid and the stigmatellin biosynthetic gene cluster of Stigmatella aurantiaca Sg a15 and a combined polyketide-(poly)peptide gene cluster from the epothilone producing strain Sorangium cellulosum So ce90

Myxobacterial strains producing polyketides (PKs) assumed to be biosynthesized by a type I polyketide synthase (PKS) were analysed. Myxobacteria also produce a variety of polypeptides (PP) and PKs with incorporated amino acids ('mixed PK-PP'). In order to be able to identify the biosynthetic gene clusters for these metabolites a PCR based approach has been developed to clone ketosynthase (KS) domains of PKS genes from these organisms. Conserved regions of peptide synthetases of the non-ribosomal type (NRPS) were also amplified via PCR. KS fragments from Stigmatella aurantiaca Sg a15 were used for chromosomal gene inactivation experiments resulting in a series of mutants including such that were unable to produce stigmatellins and myxalamids. A NRPS fragment and PKS fragments from Sorangium cellulosum So ce90 were used to identify cosmids hybridizing with both types of probes from a genomic library. Both a NRPS and a PKS fragment were cloned and sequenced from a relatively short restriction fragment of one of these cosmids. The method described here should be very useful to clone and identify PKS, NRPS and mixed PKS-NRPS from myxobacteria in general and thereby open opportunities to use the biochemical diversity of these bacteria for genetic engineering and combinatorial biosynthesis.

Apicularens A and B, new cytostatic macrolides from Chondromyces species (myxobacteria): production, physico-chemical and biological properties

A novel macrolide, apicularen A, was produced by several species of the genus Chondromyces. Initially it was discovered by bioassay-guided RP-HPLC-fractionation of culture extracts of Chondromyces robustus, strain Cm a13. Apicularen A showed no antimicrobial activity, but was highly cytotoxic for cultivated human and animal cells, with IC50 values ranging between 0.1 and 3 ng/ml. A cometabolite of apicularen A, the N-acetylglucosamine glycoside apicularen B, was distinctly less cytotoxic with IC50 values between 0.2 and 1.2 microg/ml, and showed weak activity against a few Gram-positive bacteria. Apicularen A is chemically closely related to the salicylihalamides A and B from the marine sponge Haliclona sp.

The chondramides: cytostatic agents from myxobacteria acting on the actin cytoskeleton

BACKGROUND

Chondramides are cyclodepsipeptides produced by strains of the myxobacterium, Chondromyces crocatus. These peptides, which have been reported to inhibit yeast and mammalian cell proliferation, are related to jasplakinolide, which has been isolated from marine sponges of the genus Jaspis and has been shown to interfere with the actin cytoskeleton (a structural component of cells that helps maintain their shape and is involved in processes, such as cell division and cell locomotion). We studied the effects of the chondramides (A, B, C, and D) on tumor cell growth, on cytoskeletal structure, and on actin polymerization in vitro and compared these effects with those of cytochalasin D and jasplakinolide.

METHODS

Cell proliferation was measured by means of tetrazolium salt reduction assays. Effects on the cytoskeleton were studied by use of fluorescence techniques, and actin polymerization in vitro was measured by means of viscosimetry.

RESULTS

Proliferation of tested tumor cell lines was inhibited by the chondramides. Concentrations that inhibited proliferation by 50% (IC50 values) ranged from 3 to 85 nM and were of the same order of magnitude as those found for cytochalasin D and jasplakinolide. Fluorescence staining of potoroo cells incubated with chondramides A and B showed that organization of the actin cytoskeleton was disrupted; however, the microtubule system was not affected. Viscosimetric measurement showed that, depending on the experimental conditions, chondramide A induced or accelerated actin polymerization in vitro.

CONCLUSION

The chondramides--unlike jasplakinolide--can be produced in large amounts by fermentation, and, similar to jasplakinolide, they appear to have antiproliferative activity against carcinoma cell lines by targeting the actin cytoskeleton.

Restoration of the Mendelian transmission ratio by a deletion in the mouse chromosome 1 HSR

The house mouse, Mus musculus, harbours a variable cluster of long-range repeats in chromosome 1. As shown in previous studies, some high-copy clusters such as the MUT cluster are cytogenetically apparent as a homogeneously staining region (HSR) and are associated with a distortion of the Mendelian recovery ratio when transmitted by heterozygous females. The effect is caused by a decreased viability of +/+ embryos. It is compensated by maternal or paternal MUT. In this study, a deletion derivative of MUT, MUTdel, shows normal transmission ratios and no compensating capability. In this respect, MUTdel behaves like a wild-type cluster. Hence, both properties--transmission ratio distortion and compensating capability--map to the deleted region. The deletion comprises three-quarters of the MUT HSR and does not extend to the nearest markers adjacent to the HSR.

Evolution by fusion and amplification: the murine Sp100-rs gene cluster

Sp100 is a single-copy gene in the human and the mouse. A related gene, Sp100-rs, occurs in multiple copies and forms a conspicuous cluster in the mouse chromosome 1. Murine Sp100 and Sp100-rs are homologous from the promoter up to a position in intron 3, but they differ 3' of that position. In the genus Mus, Sp100-rs is present in one phylogenetic branch, represented by the house mouse, M. musculus, but probably does not exist in another branch, represented by M. caroli. Thus, Sp100-rs arose relatively late in the evolution of the genus Mus, whereas Sp100 existed in the common ancestor of the human and the mouse. The Sp100-rs gene cluster probably evolved by gene fusion followed by amplification and diversification.

Structure and expression of the murine Sp100 nuclear dot gene

The human SP100 gene encodes an autoantigen that colocalizes with two other proteins, PML and NDP52, in distinct nuclear domains, called "nuclear dots" (NDs). NDs do not overlap with other known subnuclear structures, and their function is still unknown. Patients suffering from the autoimmune disease primary biliary cirrhosis often produce antibodies against the SP100 protein. The present study describes the structure and expression of the murine Sp100 gene. In the species Mus caroli, Sp100 consists of 17 exons that are distributed over a range of 52 kb. The human and murine Sp100 promoters are very similar, and both harbor an interferon-stimulated response element. Like its human counterpart, the murine Sp100 gene is responsive to interferon treatment. The house mouse, Mus musculus, harbors the Sp100 gene and a second gene with homology to Sp100, the multicopy Sp100-rs gene. However, in contrast to the genuine mouse homolog, Sp100-rs shares only segmental homology with the human Sp100 gene. Replacement of the murine Sp100 gene by a defective copy is now feasible and should shed light on its function in an animal model.

Distortion of Mendelian recovery ratio for a mouse HSR is caused by maternal and zygotic effects

An HSR in chromosome 1 which is found in many feral populations of Mus musculus domesticus was shown in previous studies to consist of a high-copy long-range repeat cluster. One such cluster, MUT, showed distorted transmission ratios when introduced by female parents. MUT/+ offspring were preferentially recovered at the expense of +/+ embryos in the progeny of male MUT/+ x female +/+ but were found at the expected 1:1 ratio in reciprocal crosses. Preferential recovery of maternal MUT was due to lethality of postimplantation +/+ embryos. There was no distortion of the recovery ratio in MUT/+ x MUT/MUT progeny: maternal MUT and + clusters were present among live implants at a 1:1 ratio. Maternal and zygotic effects therefore contribute to the phenomenon. The mechanism of their interaction is unknown.

Copy numbers of a clustered long-range repeat determine C-band staining

A cluster of long-range repeats (LRRs) with a repeat size of roughly 100 kb is part of band D of chromosome 1 of the house mouse, Mus musculus. The cluster is cytogenetically polymorphic: it is either C-band negative or C-band positive. Our results show that the differential staining behavior depends on the LRR copy number and not on differences in DNA composition. There is a threshold between 105 and 175 LRR copies per haploid genome; clusters with lower copy numbers stain C-band negative, whereas those with higher copy numbers are C-band positive. Above this threshold, the size of the C-band is linearly correlated with the LRR copy number. The results imply that sequences capable of forming heterochromatin may be dispersed throughout the genome but are not recognized as such by cytogenetic techniques, unless they reach the threshold amount and concentration.

Chondramides A approximately D, new antifungal and cytostatic depsipeptides from Chondromyces crocatus (myxobacteria). Production, physico-chemical and biological properties

Novel depsipeptides, named chondramides were produced at levels up to 4.3 mg/liter by several myxobacteria of the genus Chondromyces. The compounds are structurally closely related to jaspamide/jasplakinolide from marine sponges of the genus Jaspis. Initially the chondramides were detected in acetone extracts of the biomass of Chondromyces crocatus, strain Cm c2. So far, four structural variants could be characterized, the chondramides A approximately D. They inhibited the growth of a few yeasts and showed high cytostatic activity against cultivated human and animal cells.

A transcript family from a long-range repeat cluster of the house mouse

A family of closely related genes is a component of the polymorphic long-range repeat cluster D1Lub1 of the house mouse. Members of the gene family have diverged from one another by rearrangements and point mutations. D1Lub1 cluster have low (approximately 50) or high (> or = 500) copy numbers. In mice with high-copy clusters five or six poly(A)+ RNAs are found, while in mice with low-copy clusters only a single member of the RNA family is detected. The RNA family is synthesized in a tissue-independent manner. Each member of the RNA family is defined by a set of DNA probes. Cross hybridization with the probes reveals common 5' regions and variable remaining parts. The RNA variants are probably transcribed from different gene copies.

A member of the mouse LRR transcript family with homology to the human Sp100 gene

A previously isolated cDNA sequence with homology to the long-range repeat (LRR) cluster in chromosome 1 of the house mouse, Mus musculus, was identified as derived from a 1.3 kb polyadenylated RNA. This transcript belongs to a family of polyadenylated RNAs which are synthesized from a multicopy gene included in the LRR copies. The representation of the 1.3 kb transcript in genomic DNA was studied in lambda and cosmid clones from the LRR cluster. Two different types of LRRs were detected with respect to the arrangement of coding regions. In the type-1 arrangement, the sequence is split into five exons, and in the type-2 arrangement, into six exons. The respective exons with their flanking regions were sequenced. The analysis of splice signals revealed that LRR copies with a type-1 arrangement are presumably the source of the 1.3 kb transcript. The 1.3 kb transcript has sequence homology to a human gene encoding Sp100, a nuclear antigen recognized by autoantibodies from patients suffering from some autoimmune diseases including primary biliary cirrhosis. Mouse exons II and III exhibit 71% homology at the nucleotide level and 56% homology at the amino acid level to the human Sp100 cDNA. We mapped the human Sp100 gene to chromosome 2. This location corroborates the assumption that the human Sp100 gene and the mouse LRR gene are homologous, as the human chromosome 2 contains the segment which is homologous to the mouse LRR region.

Identification of HLA-DRB1 and HLA-DQB1 identical individuals by a cytokine-based mixed lymphocyte culture

Cytokine determination in MLC is under discussion as providing more sensitive and specific information regarding host-graft compatibility, and is therefore suggested to represent a new method for transplantation medicine. Little is known, however, about the stimulatory influence of HLA class II antigens and minor lymphocyte-stimulating antigens (Mls). Our results demonstrate that cytokine determination in MLC is suitable to detect identical alleles of HLA-DRB1 and HLA-DQB1. Among more than 100 random MLC experiments, we observed one cytokine pattern similar to the cytokine release detected in a control MLC of HLA-identical siblings, which showed marginal or no secretion of IL-2, sIL-2R, IFN-gamma, TNF-alpha, and IL-6. HLA-typing of these two nonreactive individuals elevated identical HLA-DRB1 and HLA-DQB1 regions, while they differed in the HLA-DP locus. This suggests that HLA-DP has no stimulatory influence on cytokine release. Further investigation of the stimulatory capacity of HLA-DR and DQ showed that HLA-DR is more effective in inducing IFN-gamma release than HLA-DQ. To evaluate the stimulatory influence of human Mls, i.e., human endogenous retroviruses (HERV), we analyzed HERV sequences of nonreactive individuals. Both individuals showed identical HERV patterns. A third individual, who had shown distinct cytokine release in MLC with both nonreactive individuals, differed in the HERV fragments. In conclusion, cytokine determination in MLC is a new method of evaluating the biological relevance of stimulatory antigens after allogeneic stimulation detecting all individual diversities in one experiment.

Crocacin, a new electron transport inhibitor from Chondromyces crocatus (myxobacteria). Production, isolation, physico-chemical and biological properties

Crocacin was isolated from the biomass of the myxobacterium Chondromyces crocatus, strain Cm c3. It inhibited the growth of a few Gram-positive bacteria and a wide spectrum of yeasts and molds. In beef heart submitochondrial particles, crocacin blocked the electron transport within the bc1-segment (complex III) and caused a red shift in the reduced spectrum of cytochrome b with a maximum at 569 nm.

Two binding sites of inhibitors in NADH: ubiquinone oxidoreductase (complex I). Relationship of one site with the ubiquinone-binding site of bacterial glucose:ubiquinone oxidoreductase

The effect of ten naturally occurring and two synthetic inhibitors of NADH:ubiquinone oxidoreductase (complex I) of bovine heart, Neurospora crassa and Escherichia coli and glucose:ubiquinone oxidoreductase (glucose dehydrogenase) of Gluconobacter oxidans was investigated. These inhibitors could be divided into two classes with regard to their specificity and mode of action. Class I inhibitors, including the naturally occurring piericidin A, annonin VI, phenalamid A2, aurachins A and B, thiangazole and the synthetic fenpyroximate, inhibit complex I from all three species in a partially competitive manner and glucose dehydrogenase in a competitive manner, both with regard to ubiquinone. Class II inhibitors including the naturally occurring rotenone, phenoxan, aureothin and the synthetic benzimidazole inhibit complex I from all species in an non-competitive manner, but have no effect on the glucose dehydrogenase. Myxalamid PI could not be classified as above because it inhibits only the mitochondrial complex I and in a competitive manner. All inhibitors affect the electron-transfer step from the high-potential iron-sulphur cluster to ubiquinone. Class I inhibitors appear to act directly at the ubiquinone-catalytic site which is related in complex I and glucose dehydrogenase.

Nannochelins A, B and C, new iron-chelating compounds from Nannocystis exedens (myxobacteria). Production, isolation, physico-chemical and biological properties

Novel citrate-hydroxamate siderophores, named nannochelins A, B and C, were isolated from the culture broth of the myxobacterium Nannocystis exedens strain Na e485. The new substances showed weak growth-inhibitory activity against some bacteria and fungi.

[The noninvasive diagnosis of coronary heart disease in women. The exercise ECG or ST-segment analysis in the long-term ECG?]

The diagnostic value of an exercise ECG in women with the clinical symptoms of stable angina is limited because of its low accuracy in demonstrating coronary heart disease. A study of ambulatory patients was undertaken, involving 143 men and 29 women (mean age 55 [37-70] years), to determine whether ST-segment analysis of the 24-hour ECG gives better results, the coronary arteriogram providing the standard of comparison. 24-hour monitoring and the exercise ECG gave similar diagnostic results (66% vs 67%) in the 143 men. But in the 29 women 24-hour monitoring was diagnostically superior to the exercise ECG (76% vs 45%; P less than 0.01), as a result of a significantly higher specificity (64% vs 29%; P less than 0.05) and a tendency towards higher sensitivity (87% vs 60%; P = 0.13). As expected, the accuracy of the exercise ECG was thus lower in women than in men (P less than 0.05). There were no significant gender-specific differences for accuracy of 24-hour monitoring (76% in women, 66% in men; P less than 0.15). These data indicate that in women ST-segment analysis of the 24-hour ECG is better than the exercise ECG for demonstrating coronary heart disease.

Diagnostic value of ambulatory Holter monitoring for the detection of coronary artery disease in patients with variable threshold angina pectoris

Patients with chronic stable angina pectoris may present with either fixed or variable threshold symptoms. To evaluate the diagnostic value of ambulatory Holter monitoring for the detection of coronary artery disease (CAD) in patients with variable threshold angina, 216 consecutive candidates for coronary angiography were investigated prospectively. For comparison, a group of 55 consecutive patients with fixed threshold angina was studied under the same conditions. Patients with prior myocardial infarction or angiographically documented CAD were excluded. Within 4 months of Holter monitoring, the advised coronary angiography was performed in 77% of the patients with variable threshold angina and in 89% of the patients with fixed threshold angina (p less than 0.05). The prevalence of CAD was markedly lower in patients with variable threshold angina compared to patients with fixed threshold angina (54 vs 90%, p less than 0.001). CAD patients of both subgroups, however, did not differ significantly with respect to the number of obstructed vessels, the Gensini coronary score, the number with impaired left ventricular function (ejection fraction less than 50%) or the duration of ischemic episodes during Holter monitoring. Diagnostic accuracy of Holter monitoring did not differ between variable and fixed threshold angina groups (67 vs 78%). In 91% of the patients results obtained by Holter monitoring could be compared to the results of a bicycle stress test. In patients with fixed threshold angina the diagnostic accuracy was similar for both tests (80 vs 80%). In patients with variable threshold angina, the diagnostic accuracy of Holter monitoring exceeded that of the exercise stress test (68 vs 55%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Silent myocardial ischemia as a potential link between lack of premonitoring symptoms and increased risk of cardiac arrest during physical stress

The risk of cardiac arrest is increased during strenuous physical exercise in patients with stable coronary artery disease (CAD). Because premonitoring symptoms are rarely observed, silent myocardial ischemia may represent the pathophysiological basis for the induction of malignant ventricular arrhythmias. Holter monitoring was, therefore, performed in 40 consecutive patients entering a randomized intervention trial on progression of CAD. In 20 of 21 participants (95%) in the intervention program greater than or equal to 1 episode of silent myocardial ischemia was observed during the initial training session. The mean duration of silent myocardial ischemia per patient was 25 +/- 13 min/hr of training session. During normal daily activity only 5 patients (24%) experienced greater than or equal to 1 episode of silent myocardial ischemia (p less than 0.001) yielding a mean duration of 0.6 +/- 1.3 minutes of silent myocardial ischemia/hr of ordinary activity per patient (p less than 0.001 vs training session). During a control period of 24 hours without exercise training the incidence (33%) and mean duration of silent myocardial ischemia (0.8 +/- 2.1 min/hr/patient) were similar to those during normal daily activity on the day of the training session. During the training session the occurrence of frequent or repetitive ventricular arrhythmias was related to 10 silent myocardial ischemia episodes detected in 5 patients. During normal daily activity in 1 patient only was the onset of malignant ventricular arrhythmias associated with silent myocardial ischemia (p less than 0.05). Conditions and results of the Holter studies in the control group patients were comparable to those of the patients in the intervention group on the day without physical exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

[Validation of trend-supported ST segment analysis of long-term ECG recordings]

Trend recordings of relative ST-segment deviations represent a useful tool for the identification of ischemia-like episodes during Holter monitoring. For the generation of trend recordings beat-to-beat data are filtered. The influence of the time constant of the filter on the sensitivity and the specificity for the detection of ischemia-like ECG changes is unknown, however. Ischemia-like episodes were, therefore, simulated and recorded by a frequency modulated Holter recorder and by a conventional six-channel ECG system. Relative ST-segment deviations were filtered using a time constant of 8, 16, 32 or 64 s, or an arithmetic averaging over 9 s for the generation of ST-segment trends. The magnitude of short-lasting ST-segment deviations was underestimated, when beat-to-beat data were filtered using time constants of greater than or equal to 32 s. The influence of posture-related ECG changes on the ST-segment trends was investigated by recording lead CM5 in 14 consecutive patients in different positions by a conventional ECG system. Four out of the 14 patients developed ST-segment elevations greater than or equal to 0.1 mV during leftsided position. Only in these four patients were ST-segment deviations of similar magnitude recorded during the following Holter monitoring. The posture-related ST-segment changes were characterized by an abrupt onset and an abrupt end, resulting in a box-like shape which enabled their correct identification in the ST-segment trend analysis. In order to determine the relative frequency of posture-related ST-segment changes, 35 patients with coronary artery disease (CAD) and 35 patients without underwent Holter monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Myxochelin A, a new iron-chelating compound from Angiococcus disciformis (Myxobacterales). Production, isolation, physico-chemical and biological properties

Myxochelin A, a new catechole siderophore, was isolated from the culture broth of the myxobacterium, Angiococcus disciformis strain An d30. As is the case with other iron-chelating compounds the production of myxochelin A could be markedly increased up to 44 mg/liter by fermentation at low iron concentrations (10(-7) M FeCl3). The new substance showed weak activity against some bacteria.