Inpatient surgical treatment of paediatric proximal humerus fractures between 2000 and 2012

PURPOSE

To estimate the rate of surgical treatment of paediatric proximal humerus fractures over time utilizing a large, publicly available national database.

METHODS

The Healthcare Cost and Utilization Project Kids' Inpatient Database was evaluated between the years 2000 and 2012. Proximal humerus fractures were identified using International Classification of Diseases, 9^th Revision, Clinical Modification (ICD-9 CM) diagnosis codes. ICD-9 CM procedure codes were used to identify patients who received surgical treatment. Univariable and multivariable logistic regression were used to determine variables associated with greater proportions of surgical treatment. All statistical analyses were performed utilizing SAS statistical software v.9.4. Statistical significance was set at p < 0.05.

RESULTS

A total of 7520 proximal humerus fracture admissions were identified; 3247 (43.2%) were treated surgically. The percentage of patients receiving surgery increased from 39.3% in 2000 to 46.4% in 2012 (p < 0.001). After adjustment for potential confounders, increased age, increased ICD-9 derived injury severity scores (ICISS) and more recent year were associated with an increased proportion of patients receiving surgical treatment (p < 0.001). Medicaid payer status (p < 0.001) and admission to a children's hospital (p = 0.045) were associated with a lower proportion of surgical treatment.

CONCLUSION

The rate of operative treatment of paediatric proximal humerus fractures increased over time between 2000 and 2012. Increased surgical rates were independently associated with older age, increased ICISS, treatment at a non-children's hospital and non-Medicaid insurance status. Further study is needed to provide evidence to support improved outcomes after operative treatment of paediatric proximal humerus fractures.

Increasing rates of surgical treatment for paediatric diaphyseal forearm fractures: a National Database Study from 2000 to 2012

FOREARM

Purpose fractures are one of the most commonly sustained injuries in children and are often treated non-operatively. The purpose of this study was to estimate the rate of inpatient surgical treatment of paediatric forearm fractures over time using a large, publicly available, national database.

METHODS

The Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID) was evaluated between 2000 and 2012. Forearm fractures and surgeries were identified using International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9 CM) diagnosis and procedure codes. Univariable and multivariable logistic regression were used to determine variables associated with greater proportion of surgical treatment. All statistical analyses were performed using SAS statistical software v.9.4 (SAS Institute Inc., Cary, NC, USA). Statistical significance was set at p < 0.05.

RESULTS

The database identified 30 936 forearm fracture admissions. Overall, 19 837 of these patients were treated surgically (64.12%). The percentage of patients treated with surgery increased from 59.3% in 2000 to 70.0% in 2012 (p < 0.001). Multivariable regression analysis found increased age (p < 0.001), more recent year (p < 0.001), male gender (p = 0.003) and admission to a children's hospital (p < 0.001) were associated with an increased proportion of patients receiving surgical treatment. Medicaid payer status was associated with a lower proportion of surgical treatment (p < 0.001).

CONCLUSIONS

The rate of operative treatment for paediatric forearm fractures admitted to the hospital increased over time. Increased surgical rates were associated with older age, male gender, treatment at a children's hospital and non-Medicaid insurance status.

Comparative mathematical modelling of a green approach for bioaccumulation of cobalt from wastewater

Cobalt is an essential element, but its wide use in industry generates important environmental and biological problems. The present study explores theoretical and empirical models of a green process for cobalt {Co²⁺} bioaccumulation from aqueous solutions. Two Gram-positive Bacillus subtilis species, strains CECT 4522 and LMM (the latter a former laboratory isolate from wastewater samples, which was phylogenetically characterized for the present work), were selected among others as the best Co²⁺ accumulation systems. Mathematical models representing kinetic and steady-state conditions for discrete and large amounts of bacterial biomass were expanded. In this way, it was possible to theoretically calculate the amount of Co²⁺ retained on the outer cell wall layer and incorporated inside the cell at any time. Theoretical and empirical hyperbolic-type models were suitable to fit the experimental bioaccumulation data for discrete amounts of bacteria biomass. In addition, kinetic relationships between the amount of Co²⁺ accumulated and the time before (or after) reaching steady state were established for large amounts of bacterial biomass. Other kinetic approaches were also satisfactorily tested. The two Gram-positive bacteria assayed are promising agents for developing heavy metal removal systems from industrial waste.

Indications and anatomic landmarks for the application of lower extremity traction: a review

PURPOSE

Fractures of the lower extremity, particularly of the femur and acetabulum, may be difficult to immobilize with splinting alone. These injuries may be best stabilized with the application of various types of skeletal traction. Often, traction is applied percutaneously in an emergent setting, making the knowledge of both superficial and deep anatomy crucial to successful placement.

METHODS

Review was performed via PubMed search as well as referencing the Orthopaedic literature. Relevant articles to the anatomy of the knee, ankle and calcaneus as they pertain to traction placement were referenced in compiling the optimal recommendations for traction placement.

CONCLUSION

By palpating and marking superficial landmarks and observing specific anatomic relationships, safe application of traction pins can be performed while minimizing iatrogenic injury to vital anatomic structures, and avoiding intra-articular placement which could potentially lead to joint infection.

Choosing the best image processing method for masticatory performance assessment when using two-coloured specimens

Objective masticatory performance assessment using two-coloured specimens relies on image processing techniques; however, just a few approaches have been tested and no comparative studies are reported. The aim of this study was to present a selection procedure of the optimal image analysis method for masticatory performance assessment with a given two-coloured chewing gum. Dentate participants (n = 250; 25 ± 6·3 years) chewed red-white chewing gums for 3, 6, 9, 12, 15, 18, 21 and 25 cycles (2000 samples). Digitalised images of retrieved specimens were analysed using 122 image processing methods (IPMs) based on feature extraction algorithms (pixel values and histogram analysis). All IPMs were tested following the criteria of: normality of measurements (Kolmogorov-Smirnov), ability to detect differences among mixing states (anova corrected with post hoc Bonferroni) and moderate-to-high correlation with the number of cycles (Spearman's Rho). The optimal IPM was chosen using multiple criteria decision analysis (MCDA). Measurements provided by all IPMs proved to be normally distributed (P < 0·05), 116 proved sensible to mixing states (P < 0·05), and 35 showed moderate-to-high correlation with the number of cycles (|ρ| > 0·5; P < 0·05). The variance of the histogram of the Hue showed the highest correlation with the number of cycles (ρ = 0·792; P < 0·0001) and the highest MCDA score (optimal). The proposed procedure proved to be reliable and able to select the optimal approach among multiple IPMs. This experiment may be reproduced to identify the optimal approach for each case of locally available test foods.

The present Pyrenean population of bearded vulture (Gypaetus barbatus): its genetic characteristics

The Pyrenean population of the endangered bearded vulture (Gypaetus barbatus) is the largest natural population in Europe. In this study, its current genetic variability was assessed using 110 animals of the recent population in order to know what the present situation. Sex identification by DNA methodology in the 110 bearded vultures, mitochondrial DNA (mtDNA) and eight microsatellite markers in 87 bearded vultures have been analysed. Our results for sex identification present a number of 49 males and 61 females; no significant differences for number of males and females in this population have been observed. mtDNA studies indicate that nucleotide and haplotype diversities and number of variable sites were low. Tajima's D test and Fu and Li's D* and F* tests suggest that mutations are selectively neutral and the population is expanding. A mean number of alleles per locus and a mean observed heterozygosity have been obtained by microsatellite analysis. FIS is not high, and inbreeding depression could be discarded in the near future. The results suggest that the Pyrenean population of bearded vultures have to be controlled in order to avoid the loss of genetic variability. This data should be taken into account when considering conservation plans for the species.

Identification of the emerging skin pathogen Corynebacterium amycolatum using PCR-amplification of the essential divIVA gene as a target

The actinomycete Corynebacterium amycolatum is a saprophytic bacterium usually associated with the human skin, but it is at present considered an emergent pathogen as it is isolated from nosocomial settings from samples of immunosuppressed patients. The conventional method to distinguish C. amycolatum from closely related species is mainly based on phenotypic or chemotaxonomic studies. We developed a molecular method to identify rapidly C. amycolatum based on the use of different primers for amplification of the cell division divIVA gene using conventional or real-time PCR. This technique was used for the first time to distinguish C. amycolatum from the closely related Corynebacterium striatum, Corynebacterium minutissimum and Corynebacterium xerosis, without the requirement of further molecular analysis. The suitability of the identification method was tested on 51 clinical isolates belonging to the nonlipophilic fermentative group of corynebacteria (cluster C. striatum/C. amycolatum), which were accurately characterized by sequencing a 0.8 kb fragment of the 16S rRNA gene.

Retention of inorganic arsenic by coryneform mutant strains

The natural resistance mechanisms of corynebacteria to respond to the environments containing high levels of arsenic were successfully adopted to develop inexpensive and selective extractants for submicrogram amounts of arsenic. Kinetic and equilibrium characteristics were evaluated, and a preliminary exploration of the capability of these strains to be used for arsenic speciation was also made in this work. Three kinetics models were used to fit the experimental data. It was found that the pseudo-first-order kinetics model was not quite adequate to describe the retention process, while the intraparticle diffusion and the pseudo-second-order kinetics models provide the best fits. The equilibrium isotherm showed that the retention of arsenic was consistent with the Langmuir equation and that the Freundlich and Dubinin-Radushkevich models provided poorer fits to the experimental data. The maximum effective retention capacity for arsenic was about 15.4 ng As/mg biomass. The amount of arsenic retained was directly measured in the biomass by forward planning a slurry electrothermal atomic absorption spectrometric procedure.

Training with Computer-Supported Motor Imagery in Post-Stroke Rehabilitation

Converging lines of evidence suggest that motor imagery (the mental simulation of a motor act within working memory) is associated with subliminal activation of the motor system. This observation has led to the hypothesis that cortical activation during motor imagery may affect the acquisition of specific motor skills and help the recovery of motor function. In this paper, we describe a clinical protocol in which we use interactive tools to stimulate motor imagery in hemiplegic stroke patients, thereby helping them to recover lost motor function. The protocol consists of an inpatient and an outpatient phase, combining physical and mental practice. In the inpatient phase, patients are trained in a laboratory setting, using a custom-made interactive workbench (VR Mirror). After discharge, patients use a portable device to guide mental and physical practice in a home setting. The proposed strategy is based on the hypotheses that: (a) combined physical and mental practice can make a cost-effective contribution to the rehabilitation of stroke patients, (b) effective mental practice is not possible without some form of support, from a therapist (as in our inpatient phase) or from technology (as in the outpatient phase), (c) the inclusion of an outpatient phase will allow the patient to practice more often than would otherwise be possible, therefore increasing the speed and/or effectiveness of learning, and (d) the use of interactive technology will reduce the patient's need for skilled support, therefore improving the cost-effectiveness of training.

Streptomyces lividans and Brevibacterium lactofermentum as heterologous hosts for the production of X22 xylanase from Aspergillus nidulans

The Aspergillus nidulans gene xlnA coding for the fungal xylanase X22 has been cloned and expressed in two heterologous bacterial hosts: Streptomyces lividans and Brevibacterium lactofermentum. Streptomyces strains yielded 10 units/ml of xylanase when the protein was produced with its own signal peptide, and 19 units/ml when its signal peptide was replaced by the one for xylanase Xys1 from Streptomyces halstedii. B. lactofermentum was also able to produce xylanase X22, affording 6 units/ml upon using either the Aspergillus xlnA signal peptide or Streptomyces xysA. These production values are higher than those previously reported for the heterologous expression of the A. nidulans xlnA gene in Saccharomyces cerevisiae (1 unit/ml). Moreover, the X22 enzyme produced by Streptomyces lividans showed oenological properties, indicating that this Streptomyces recombinant strain is a good candidate for the production of this enzyme at the industrial scale.

Polyene antibiotic biosynthesis gene clusters

Over the past 15 years the biosynthetic gene clusters for numerous bioactive polyketides have been intensively studied and recently this work has been extended to the antifungal polyene macrolides. These compounds consist of large macrolactone rings that have a characteristic series of conjugated double bonds, as well as an exocyclic carboxyl group and an unusual mycosamine sugar. The biosynthetic gene clusters for nystatin, pimaricin, amphotericin and candicidin have been investigated in detail. These clusters contain the largest modular polyketide synthase genes reported to date. This body of work also provides insights into the enzymes catalysing the unusual post-polyketide modifications, and the genes regulating antibiotic biosynthesis. The sequences also provide clues about the evolutionary origins of polyene biosynthetic genes. Successful genetic manipulation of the producing organisms leading to production of polyene analogues indicates good prospects for generating improved antifungal compounds via genetic engineering.

Candicidin biosynthesis in Streptomyces griseus

The biosynthesis of the aromatic polyene macrolide antibiotic candicidin, produced by Streptomyces griseus IMRU 3570, begins with a p-aminobenzoic acid (PABA) molecule which is activated to PABA-CoA and used as starter for the head-to-tail condensation of four propionate and 14 acetate units to produce a polyketide molecule to which the deoxysugar mycosamine is attached. Using the gene coding for the PABA synthase ( pabAB) from S. griseusIMRU 3570 as the probe, a 205-kb region of continuous DNA from the S. griseus chromosome was isolated and partially sequenced. Some of the genes possibly involved in the biosynthesis of candicidin were identified including part of the modular polyketide synthase (PKS), genes for thioesterase, deoxysugar biosynthesis, modification, transport, and regulatory proteins. The regulatory mechanisms involved in the production of candicidin, such as phosphate regulation, were studied using internal probes for some of the genes involved in the biosynthesis of the three moieties of candicidin (PKS, aromatic moiety and amino sugar). mRNAs specific for these genes were detected only in the production medium (SPG) but not in the SPG medium supplemented with phosphate or in the inoculum medium, indicating that phosphate represses the expression of genes involved in candicidin biosynthesis. The modular architecture of the candicidin PKS and the availability of the PKSs involved in the biosynthesis of three polyene antibiotics (pimaricin, nystatin, and amphotericin B) shall make possible the creation of new, less toxic and more active polyene antibiotics through combinatorial biosynthesis and targeted mutagenesis.

GeRTiSS: Generic Real Time Surgery Simulation

Minimally invasive surgery is a technique that permits interventions through very small incisions. This minimises the patients' trauma and permits a faster recovery in comparison with classical surgery. The disadvantage of this surgery technique, though, is its complexity, requiring a high training effort of the surgeon. In this paper, we present a general surgery simulator for training surgeons in minimally invasive surgery. The application allows to create environments and interaction modes very similar to those encountered in real surgical interventions. The virtual environments are optionally composed of an actual patient's organs the intervention on which one desires to practice in a beforehand manner, or of synthetically generated organs with arbitrary pathologies. The intervention is carried out by means of haptic interfaces with force feedback, providing the surgeon with a sense of touch, a fundamental element of all types of surgery.

Construction of a xylanase-producing strain of Brevibacterium lactofermentum by stable integration of an engineered xysA gene from Streptomyces halstedii JM8

A xylanolytic strain of Brevibacterium lactofermentum containing the Streptomyces halstedii His-tagged xysA gene was generated. The new strain contains DNA derived from S. halstedii, expresses xylanolytic activity, and was obtained by an integrative process mediated by a conjugative plasmid targeted to a dispensable chromosomal region located downstream from the essential cell division gene ftsZ. The His-tagged Xys1 enzyme was constitutively expressed under the control of the kan promoter from Tn5 and was easily purified by use of Ni-nitrilotriacetic acid-agarose. The new strain is stable for more than 200 generations, lacks any known antibiotic resistance gene, and does not need any selective pressure to maintain the integrated gene. This strategy can be used to integrate any gene into the B. lactofermentum chromosome and to maintain it stably without the use of antibiotics for selection.

Expression of the genes coding for the xylanase Xys1 and the cellulase Cel1 from the straw-decomposing Streptomyces halstedii JM8 cloned into the amino-acid producer Brevibacterium lactofermentum ATCC13869

The xylanase ( xysA) and the cellulase ( celA1) genes from Streptomyces halstedii JM8 were cloned into Escherichia coli/ Brevibacterium lactofermentum shuttle vectors and successfully expressed in both hosts when placed downstream from the kanamycin resistance promoter (Pkan) from Tn 5 but not when under the control of their own promoters. Xylanase was secreted into the culture media of B. lactofermentum by removal of the same leader peptide as is removed in S. halstedii. The main difference between the production of xylanase by Streptomyces and corynebacteria was the low level of processing of the mature extracellular xylanase by B. lactofermentum, probably due to the lack of protease activity in this microorganism.

The cell division genes ftsQ and ftsZ, but not the three downstream open reading frames YFIH, ORF5 and ORF6, are essential for growth and viability in Brevibacterium lactofermentum ATCC 13869

The three ORFs (YFIH, ORF5 and ORF6) located downstream of the cell division genes ftsQ and ftsZ in Brevibacterium lactofermentum were disrupted by single homologous recombination events between internal fragments of the corresponding genes and the chromosomal sequences. The phenotypes of the disrupted mutants were similar to that of the wild type, suggesting that these genes are dispensable for growth and viability. However, using different plasmid constructs, it was not possible to obtain disrupted ftsZ or ftsQ mutants by single crossover events. When the ftsZ or ftsQ gene sequence was disrupted in vitro and used to replace the homologous chromosomal gene by double recombination, only single recombination events took place, and therefore no disruptants were obtained. It may be concluded therefore that, as in Escherichia coli, the cell division genes ftsQ and ftsZ are indispensable for growth and viability of B. lactofermentum. Northern hybridisation analyses performed using internal fragments of the genes coding for YFIH, ORF5 and ORF6 allowed us to dissect their transcriptional organization and to confirm the disruption of these genes.

Oral health management implications in patients with tuberous sclerosis

We report 6 cases of patients with tuberous sclerosis and concomitant dental pathosis. The multiple manifestations in tuberous sclerosis determine its impact on dental therapy. A lack of awareness of this condition may compound the possible side effects of dental treatment. Possible preventive measures by dentists are highlighted in this presentation. Medical evaluation and the control of risk factors in relation to general anesthesia and sedation are key considerations for the management of patients with tuberous sclerosis.

[Current results of the treatment of cervical metastatic lymph nodes by concurrent hyperfractionation of carboplatin and irradiation]

The results of the treatment of metastatic neck nodes is evaluated after a mean follow-up of 24 months (maximum 45 months). Fifty-seven patients with epidermoid carcinoma of the head and neck were treated according to a hyperfractionated chemoradiation schedule including two fractions a day. Each fraction consisted of 10 mg carboplatin + 115 cGy. Two fractions were given each day, five days a week, for a total dose of 700 mg carboplatin + 8050 cGy. Whenever possible, surgical salvage was performed if treated nodes persisted or recurred. Ten patients presented with N0, 8 with N1, 7 with N2a, 4 with N2b, 7 with N2c, and 21 with N3. The classification of the primary tumor was: 3 Tx, 6 T2, 9 T3 and 39 T4. One hundred and eleven nodes were treated (62 with a diameter of 1-3 cm, 26 with a diameter of 3-6 cm and 23 with a diameter over 6 cm). Actuarial node controls were: 100% for N0, 97% for nodes 1-3 cm, 87% for nodes 3-6 cm, 95% for nodes over 6 cm and 97% for the whole group. The actuarial local-regional control was 71% and the disease-free survival was 60%. These results include 5 surgical salvages (11% of N+), 2 of which recurred again (40%), while another 3 (60%) did not recur.

Identification, characterization, and chromosomal organization of the ftsZ gene from Brevibacterium lactofermentum

The ftsZ gene was cloned from the chromosomal DNA of Brevibacterium lactofermentum by the polymerase chain reaction (PCR) using two oligonucleotides designed from two conserved regions found in most of the previously cloned and sequenced ftsZ genes from other microorganisms. ftsZ is a single-copy gene in corynebacteria and is located downstream from ftsQ and murC, indicating linkage between genes involved in peptidoglycan synthesis (mur genes) and genes involved in cell division (fts genes). The organisation of the cluster is similar to that in Streptomyces and different from those of Escherichia coli or Bacillus subtilis because ftsA is not located upstream of ftsZ. The gene was expressed in E. coli using the T7 expression system; the calculated molecular weight of the expressed protein was 50 kDa. Expression of the B. lactofermentum ftsZ gene in E. coli inhibited cell division and led to filamentation. The ftsZ gene of this organism does not complement ftsZ mutations or deletions in E. coli, when cloned on low or high-copy-number vectors.

Cloning, sequencing and expression of the gene encoding elongation factor P in the amino-acid producer Brevibacterium lactofermentum (Corynebacterium glutamicum ATCC 13869)

The Brevibacterium lactofermentum EF-P gene, encoding the elongation factor protein P, was cloned and sequenced. According to DNA sequence analysis of this gene, the B. lactofermentum EF-P protein consists of 187 amino acids with a calculated molecular weight of 20,584. Southern hybridization of an internal fragment of the EF-P gene from B. lactofermentum with chromosomal DNAs from different microorganisms reveals that it is a unique gene product in B. lactofermentum and Corynebacterium glutamicum. The EF-P gene was expressed in E. coli using the T7 expression system and the calculated molecular weight of the expressed protein was 23,000. Disruption experiments using an internal fragment of the EF-P gene or a disrupted EF-P gene in suicide plasmids always failed, suggesting that the gene is needed for cell viability.

Construction of L-lysine-overproducing strains of Brevibacterium lactofermentum by targeted disruption of the hom and thrB genes

The mobilization of plasmids from gram-negative Escherichia coli to gram-positive Brevibacterium lactofermentum, mediated by P-type transfer functions, was used to construct disrupted mutants blocked specifically in the homoserine branch of the aspartate pathway. The mutant strain B. lactofermentum R31 showed an efficiency of conjugal transfer two to three orders of magnitude higher than that of the wild-type strain B. lactofermentum ATCC 13869. The hom- and thrB-disrupted mutants of B. lactofermentum ATCC 13869 were lysine overproducers. B. lactofermentum R31 mutants do not overproduce lysine because R31 is an alanine-overproducing strain and channels the pyruvate needed for lysine biosynthesis to the production of alanine.

Limitations in the use of attachments in a Mediterranean population

It has been asserted that the average height of natural teeth in Mediterranean Latin populations is relatively short and that these teeth are of insufficient size to host standard attachments manufactured by different companies. The occlusogingival height of 159 potential abutment teeth from 50 Spanish patients was measured and compared to the sizes of intracoronal and extracoronal attachments available from one manufacturer. Twenty-one abutments (13% of the sample) were smaller than the smallest intracoronal attachment available. Eighty-seven percent of the abutments in the sample would have allowed the use of an attachment. However, only 11% of the sample would have allowed the use of a large intracoronal or medium extracoronal attachment, and none would have been able to host a large extracoronal attachment. In addition, 35% of the sample could only have accepted a small intracoronal attachment. In such cases, the capacity for retention would have to be carefully evaluated.

Construction of new cloning vectors for Brevibacterium lactofermentum

Two plasmid cloning vectors (pULMJ55 and pULMJ95) were constructed for Brevibacterium lactofermentum using the origin of replication of the endogenous plasmid pBL1. Plasmid pULMJ55 is a replacement vector with transcriptional terminators from the B. lactofermentum trp operon flanking the BglII cloning sites. Religation of the BglII digested vector without insert creates a 376 bp perfect palindrome that is not tolerated in B. lactofermentum, giving positive selection for recombinant plasmids with inserts. Plasmid pULMJ95 contains the promoter-less alpha-amylase gene from Streptomyces griseus downstream of the trp terminator and is particularly suitable for the detection of promoters which are activated late during the growth phase. alpha-Amylase is secreted and its activity can be detected using simple plate tests.

Characterization of a region of plasmid pBL1 of Brevibacterium lactofermentum involved in replication via the rolling circle model

The minimal region for autonomous replication of pBL1, a 4.5-kb cryptic plasmid of Brevibacterium lactofermentum ATCC 13869 that has been used to construct a variety of corynebacterium vectors, was shown to be contained on a 1.8-kb HindII-SphI DNA fragment. This region contains two open reading frames (ORFs) (ORF1 and ORF5) which are essential for pBL1 replication in B. lactofermentum. Accumulation of single-strand intermediates in some of the constructions indicates that plasmid pBL1 replicates via the rolling circle replication model; its plus strand and minus strand were identified by hybridization with two synthetic oligonucleotide probes complementary to each pBL1 strand. ORF1 seems to encode the Rep protein and showed partial homology with sequences for Rep proteins from Streptomyces plasmids which replicate via rolling circle replication such as pIJ101, pSB24, and pJV1.

Expression of the Streptomyces griseus alpha-amylase gene in Escherichia coli

The amy gene of Streptomyces griseus was not expressed in Escherichia coli cells due to the lack of recognition of the amy promoter by the E. coli RNA polymerase, as confirmed by using promoter-probe vectors. The expression of the amy gene in E. coli was detected only when the promoter-less gene was placed under the control of the lacZ promoter and was dependent on the level of IPTG added to the medium. The extracellular alpha-amylase detected in the culture broth seems to be released by cellular lysis. When the amy gene lacking both leader peptide and promoter was transcribed from the lacZ promoter, no alpha-amylase activity was detected but larger E. coli cells and inclusion bodies were observed.

Codon preference in corynebacteria

The codon usage (CU) of 34 genes from the closely related species, Brevibacterium lactofermentum and Corynebacterium glutamicum (BLCG), was analysed and compared with that of 23 genes from other Brevibacterium and Corynebacterium species. The G+C content of the BLCG genes ranged from 50 to 62%. A wider range was found in other corynebacterial genes (25-71%). The G+C contents of non-coding regions in glutamic acid bacteria are lower than those of the coding regions and both values are lower than the G+C content of ribosomal RNA (rRNA) sequences, suggesting an unusual biased mutation pressure. The CU and synonymous codon usage (SCU) analysis showed several common characteristics among the sequenced corynebacterial genes, consistent with the close relatedness of B. lactofermentum and C. glutamicum. A subset of 25 preferred codons were deduced from the presumably highly expressed genes and they encode most of the amino acid (aa) residues of the BLCG group. An analysis of the effective number of codons (Nc) was carried out in order to check the GC3s (G+C content at the silent third position of sense codons) dependence of the CU in corynebacteria. Nc values showed differences between the BLCG group and other corynebacterial sequences. A comparison of the most used codons for each aa showed a stronger similarity to Streptomyces than to Escherichia coli. The CU/SCU tables of corynebacteria are useful for identification of protein-coding regions, including start codons when they are uncertain, and for designing oligodeoxyribonucleotide probes from an aa sequence.

The pab gene of Streptomyces griseus, encoding p-aminobenzoic acid synthase, is located between genes possibly involved in candicidin biosynthesis

The nucleotide (nt) sequence of the gene (pab) encoding p-aminobenzoic acid (PABA) synthase, a key enzyme in the biosynthesis of candicidin by Streptomyces griseus IMRU3570, was determined and an open reading frame (ORF) of 2171 nt was found. The predicted amino acid sequence demonstrated extensive sequence identity with PABA synthases (Pab) from Gram-negative Enterobacteria. The protein encoded by ORF pab shows a clear relationship at the N terminus with PabA and at the C terminus with PabB from Escherichia coli, Serratia and Klebsiella. We also determined the extent of a spontaneous deletion that removed the ORF located upstream from pab near the 5' end of the cloned fragment. The deletion occurred when the gene was cloned in the BamHI site of pBR322 and allowed pab expression in E. coli.

Expression of Streptomyces genes encoding extracellular enzymes in Brevibacterium lactofermentum: secretion proceeds by removal of the same leader peptide as in Streptomyces lividans

The alpha-amylase gene (amy) from Streptomyces griseus IMRU 3570 and the beta-galactosidase gene (lac) from S. lividans were subcloned into Brevibacterium lactofermentum or B. lactofermentum/Escherichia coli shuttle vectors. The amy gene was not expressed in B. lactofermentum from its own promoter but was efficiently expressed when the promoter of the kanamycin resistance gene (kan) was inserted upstream of the promoterless amylase gene. The lac gene from S. lividans was subcloned without its native promoter and was expressed when placed downstream of pBL1 promoters P2 or P3. The alpha-amylase was secreted extracellularly by removal of the same 28-amino acid leader peptide as in S. lividans. The amy and lac genes provide useful markers for selection of transformants and will facilitate the study of protein secretion in B. lactofermentum.

Analysis of the promoter region of saf, a Streptomyces griseus gene that increases production of extracellular enzymes

The product of the saf gene of Streptomyces griseus ATCC10137 mediated an increase in the production of several extracellular enzymes and retarded the formation of pigments and spores in Streptomyces [Daza et al., Mol. Gen. Genet. 222 (1990) 384-392]. A promoter upstream from saf was identified by subcloning a DNA fragment in the promoter probe pIJ486. Using the Escherichia coli-Brevibacterium lactofermentum promoter-probe shuttle vector, pULMJ51, we determined that the saf promoter region is also active in E. coli. The transcription start points (tsp) of the saf promoter in Streptomyces and E. coli have been determined using high-resolution S1 mapping. The tsp are at the same position in both microorganisms. Expression from the saf promoter region was negatively regulated by phosphate in Streptomyces, but not in E. coli. The amplification of the saf promoter lacking the saf coding region did not increase the production of extracellular enzymes and did not reduce sporulation or pigmentation in Streptomyces (i.e., it does not titrate out a putative repressor of the genes encoding extracellular enzymes). Several structural features of the saf promoter region and saf mRNA are studied in relation to the regulation of the saf gene expression.

Effects of replacement of promoters and modification of the leader peptide region of the amy gene of Streptomyces griseus on synthesis and secretion of alpha-amylase by Streptomyces lividans

Five different mutations were introduced into the leader peptide region of the alpha-amylase gene of Streptomyces griseus IMRU 3570. A mutation which increased the positive charge of the N-terminal region of the leader peptide enhanced the secretion of alpha-amylase by two- to threefold. Replacement of the native promoter of the amylase gene by the promoter of the Tn5 neo gene or by the promoter of the saf gene resulted in a 16-fold increase in alpha-amylase secretion. The enhanced secretion of alpha-amylase obtained by using the most efficient promoters was due to a correlated increase in the amount of transcript formed. The translation and secretion processes in S. lividans are not a bottleneck for enzyme secretion even at very high transcription rates, since stimulation of transcription of the alpha-amylase gene results in a proportionate increase in secretion of the enzyme.

Construction and characterization of promoter-probe vectors for Corynebacteria using the kanamycin-resistance reporter gene

Several multicopy promoter-probe plasmid vectors have been constructed that replicate in Brevibacterium lactofermentum and related coryneform amino acid-producing bacteria. Transcriptional activity is detected by the expression of a promoter-less aminoglycoside phosphotransferase gene (kan) derived from transposon Tn5; expression of this gene confers kanamycin resistance in B. lactofermentum. An efficient transcriptional terminator from the B. lactofermentum trp operon has been inserted upstream of the kan coding region to prevent significant transcriptional readthrough from vector promoters. The cat gene from Streptomyces acrimycini or the hygromycin-resistance gene from S. hygroscopicus are used as primary selection markers in the promoter-probe plasmid vectors. Using the promoter-probe vectors described in this paper, we have cloned several transcriptionally active fragments from the endogenous plasmid pBL1 of B. lactofermentum into Escherichia coli and/or B. lactofermentum.

Cloning, characterization and expression of an alpha-amylase gene from Streptomyces griseus IMRU3570

A gene, amy, encoding an alpha-amylase, was cloned on a 4.8 kb Sau3A fragment from the DNA of Streptomyces griseus IMRU3570. The gene was localized to a 2.27 kb fragment by subcloning and deletion mapping experiments. The gene contained an open reading frame (ORF) of 1698 nucleotides that encoded a protein of 566 amino acids with a deduced Mr of 59713 Da. Dot-blot analysis revealed that the copy number of the transcript in S. lividans transformed with the amy gene was 2.8-fold higher than in the donor S. griseus strain in good agreement with the proportionally higher secretion of amylase in S. lividans. A transcription initiation site was found approximately 64 bp upstream from the ATG translation start codon. The promoter of the amy gene was subcloned on a 290 bp HindIII--EcoRI fragment. Expression of a neomycin resistance gene from the amy promoter was negatively regulated by glucose. A 219 nucleotide fragment extending from the single BstEII site to the end of the amy gene was dispensable since active alpha-amylase was secreted after deletion of this region and coupling of a TGA translation stop codon.

[Experimental analysis of finishing lines in ceramometal restorations]

The preparation is the first step of any tooth reconstruction. The biological integration of the protesis is depending on the marginal adaptation (finish line of the preparation), occlusal adaptation (occlusal reduction), longevity of the restoration (retention and luting) and esthetics. The effect the two finish line of the preparation is studied using experimental design. In porcelain-fused-to-metal the finish line of the preparation in chanfer is superior at the beveled shoulder, because proportioning better marginal adaptation.

High transformation frequency of nonsporulating mutants of Streptomyces griseus

Three different bld mutants from S. griseus ATCC 10137 were isolated by nitrosoguanidine mutagenesis. They simultaneously lost the capability of antibiotic production and the formation of pigments. The three bld mutants were differently affected by different carbon sources. Two of these mutants showed a high efficiency of transformation with several plasmid vectors, in contrast to the low efficiency of transformation showed by the wild type. We showed that S. griseus ATCC 10137 and the three bld mutants possess an enzymatic activity that protects their DNAs against the digestion by SacI. Antibiotic and pigment production, and low transformability with plasmid DNA were together restored in spontaneous spo+ revertants.

Cloning and characterization of a gene of Streptomyces griseus that increases production of extracellular enzymes in several species of Streptomyces

A 7.2 kb Bg/II restriction fragment, which increases the production of several extracellular enzymes, including alkaline phosphatase, amylase, protease, lipase and beta-galactosidase, was cloned in Streptomyces lividans from the DNA of S. griseus ATCC 10137. This gene (named saf) showed a positive gene dosage effect on production of extracellular enzymes. When the saf gene was introduced into cells in high copy numbers it delayed the formation of pigments and spores in S. lividans and also retarded actinorhodin production in Streptomyces coelicolor. The saf gene hybridized with specific bands in the DNA of several Streptomyces strains tested. A 1 kb fragment containing the saf gene was sequenced and contains an open reading frame (ORF) of 306 nucleotides which encodes a polypeptide of Mr 10,500. This ORF is contained within a fragment of 432 bp which retained activity in Streptomyces. A fragment with promoter activity is present upstream of the saf reading frame. The predicted Saf polypeptide has a strong positive charge, and does not show a typical amino acid composition for a membrane protein, and contains a DNA-binding domain similar to those found in several regulatory proteins.

Use of a cloned gene involved in candicidin production to discover new polyene producer Streptomyces strains

A p-aminobenzoic synthase gene (pabS) from Streptomyces griseus IMRU 3570 involved in candicidin production was used as probe to find new aromatic polyene producing Streptomyces strains. The pab gene hybridizes with 6 out of 16 Streptomyces strains, and those strains which hybridize turned out to be polyene producers. Such strains were never before described as polyene producers.

Characterization and partial purification of L-asparaginase from Corynebacterium glutamicum

A high L-asparaginase (L-asparagine amidohydrolase: EC 3.5.1.1) activity was found under conditions of lysine overproduction in cultures of Corynebacterium glutamicum. L-Asparaginase was purified 98-fold by protamine sulphate precipitation. DEAE-Sephacel anion exchange, ammonium sulphate precipitation and Sephacryl S-200 gel filtration. The asparaginase protein was subjected to PAGE under non-denaturing conditions, identified by an in situ reaction and eluted from the gel in an active form. The estimated Mr from gel filtration and SDS-PAGE was 80,000. The L-asparaginase activity was inhibited by the L-asparagine analogue 5-diazo-4-oxo-L-norvaline. Neither D-asparagine nor L-glutamine was a substrate for the enzyme. L-Asparaginase was produced constitutively: its role may be that of an overflow enzyme, converting excess asparagine into aspartic acid, the direct precursor of lysine and threonine.

Nucleotide sequence of the chloramphenicol acetyltransferase gene of Streptomyces acrimycini

The nucleotide sequence of a gene (cat) encoding chloramphenicol acetyltransferase (CAT) in Streptomyces acrimycini was determined. The predicted amino acid sequence demonstrates extensive homology with those of CATs isolated from Gram-negative Enterobacteria, notably with the type III variant encoded by the IncK plasmid R387. Transcript mapping indicates a single cat mRNA with a 5' end coinciding with the AUG codon used for translational initiation in vivo. We also determined the extent of a spontaneous deletion in the 5'-noncoding DNA, which occurs when the gene is cloned in the BamHI site of pBR322 in a specific orientation and which results in constitutive cat expression in Escherichia coli from the tet promoter.

Sporulation of several species of Streptomyces in submerged cultures after nutritional downshift

Streptomyces griseus ATCC 10137, S. griseus IMRU 3570, S. griseus JI 2212, S. acrimycini JI 2236 and S. albus G sporulated abundantly in several liquid media after nutritional downshift. Spores formed in submerged cultures were viable and as thermoresistant as aerial spores. Scanning electron microscopy showed that submerged spores are morphologically similar to aerial spores. The sporulation of the Streptomyces strains tested in complex medium appeared to be triggered by phosphate nutritional downshift, induced by addition of Ca2+ to the medium. Spore-shaped bodies were formed by S. lividans JI 1326 and S. coelicolor JI 2280 when grown in complex medium supplemented with Ca2+ and proline. The thermoresistance of these spore-shaped bodies differed from that of aerial spores.

Cloning and characterization of a phosphate-regulated promoter involved in phosphate control of candicidin biosynthesis

Phosphate strongly repressed the formation of p-aminobenzoic acid (PABA) synthase, an enzyme involved in candicidin biosynthesis. Expression in Streptomyces lividans of the pabS gene (encoding PABA synthase) of Streptomyces griseus is repressed by phosphate at concentrations above 0.1 mM. However, expression of the pabS gene in Escherichia coli is not regulated by phosphate. Phosphate control of the expression of the pabS gene was observed in all plasmids containing the original 4.5-kb BamHI fragment, whereas no phosphate regulation was found when an upstream 1-kb fragment that carries the pabS promoter was deleted. Using the promoter-probe plasmid pIJ424, a '114-bp' promoter was cloned. Expression of the promoterless kanamycin phosphotransferase gene when fused to the '114-bp' promoter was strongly reduced by phosphate (90% at 5 mM concentration). The '114-bp' promoter has been sequenced and the first transcribed nucleotide identified by S1 mapping. The '114-bp' fragment is A + T-rich (54%), as compared to the Streptomyces genome (70-73% GC). The presence of a phosphate control sequence (pcs) in the upstream region of the pabS gene is proposed.

Identification of a promoter sequence in the plasmid pUL340 of Brevibacterium lactofermentum and construction of new cloning vectors for corynebacteria containing two selectable markers

A strong promoter P1 has been found in plasmid pUL340, a cloning vector used to transform corynebacteria. This promoter is also expressed efficiently in Escherichia coli. A gene (cat) for chloramphenicol acetyltransferase from Streptomyces acrimycini and a gene (hyg) for hygromycin phosphotransferase from Streptomyces hygroscopicus were subcloned in different positions of the Brevibacterium lactofermentum plasmid pUL340. Both resistance genes are expressed in B. lactofermentum from their own promoters or from the endogenous promoter in pUL340. These genes provide useful screening markers for selecting transformants of B. lactofermentum together with the kanamycin-resistance gene from the transposon Tn5.

Characterization and regulation of p-aminobenzoic acid synthase from Streptomyces griseus

p-Aminobenzoic acid synthase (PABA synthase) of Streptomyces griseus catalyses the conversion of chorismic acid to p-aminobenzoic acid (PABA), a precursor of the aromatic p-aminoacetophenone moiety of candicidin, a polyene macrolide antibiotic. This enzyme uses glutamine or ammonia as amino donors for PABA formation. Enzyme extracts converted [14C]chorismic acid to labelled PABA. PABA synthase was present in S. griseus IMRU 3570 only during the antibiotic producing phase. No detectable levels of the enzyme were found in cell-free extracts of nonproducing mutants of S. griseus obtained after UV mutagenesis. PABA synthase activity was found also in Streptomyces coelicolor var. aminophilus, producer of the polyene macrolide antibiotic fungimycin, but it was not present in extracts of several other streptomycetes that do not produce aromatic polyene macrolide antibiotics. PABA synthase (amidotransferase) activity was partially purified by DEAE-Bio-gel and Sephacryl S-200 filtrations. The estimated molecular weight was 50000. PABA synthase was repressed by aromatic amino acids and PABA but not by anthranilic acid. Inorganic phosphate strongly repressed but did not inhibit PABA synthase activity.

High-frequency transformation of Brevibacterium lactofermentum protoplasts by plasmid DNA

An efficient polyethylene glycol-assisted method for transformation of Brevibacterium lactofermentum protoplasts that uses plasmid vectors has been developed. Two small plasmids, pUL330 (5.2 kilobases) and pUL340 (5.8 kilobases), both containing the kanamycin resistance gene from transposon Tn5 and the replication origin of the natural plasmid pBL1 of B. lactofermentum, were selected as vectors. Supercoiled forms of the plasmids yielded a 100-fold higher transformation frequency than did linear forms. The optimal transformation frequency was achieved with 10 ng of DNA in 1 ml of transformation buffer. Higher concentrations of plasmid DNA resulted in a decrease in transformation frequency per microgram of DNA. Optimal transformation was obtained with 25 to 35% polyethylene glycol 6000. Under optimal conditions, 10(6) transformants per microgram of DNA were obtained.

Cloning of a chloramphenicol acetyltransferase gene of Streptomyces acrimycini and its expression in Streptomyces and Escherichia coli

A gene (cat) for chloramphenicol (Cm) acetyltransferase (CAT) was cloned from Streptomyces acrimycini into S. lividans 66 on the plasmid vector pIJ61. The cat gene was localized on a 1.7-kb BclI fragment, which probably also carries the cat promoter. This DNA fragment conferred Cm resistance, through CAT activity, on S. lividans, S. coelicolor and S. parvulus, but not on Escherichia coli when inserted in the BamHI site of the tetracycline-resistance(TcR) gene of pBR322. However, when inserted in a particular orientation in this site, spontaneous deletions of 0.7 kb led to CAT activity and Cm resistance. DNA homologous to the 1.7-kb BclI cat fragment was found in most, but not all, of a series of other streptomycetes that have CAT activity. The cat provides a potentially useful screening marker for Streptomyces cloning vectors.

Cloning and expression of a p-aminobenzoic acid synthetase gene of the candicidin-producing Streptomyces griseus

4.5-kb BamHI fragments of DNA coding for p-aminobenzoic acid (PABA) synthetase from the candicidin-producing Streptomyces griseus IMRU 3570 and from a sulphonamide resistant mutant of it were cloned on the plasmid vector pIJ41 into Streptomyces lividans 66. The cloned DNA restored prototrophy to a pab auxotroph of S. lividans; when the S. griseus donor was a sulphonamide resistant, PABA-overproducing mutant, the S. lividans clone was sulphonamide resistant as well as Pab+. Sub-cloning the 4.5-kb fragment of S. griseus DNA into Escherichia coli pabA- or pabB- mutants by insertion at the BamHI site of pBR322 did not yield prototrophic clones directly. However, when the cloned fragment had the proper orientation relative to the tet promoter, but not the opposite one, it was possible to select Pab+ colonies, which arose by deletion in vivo of approx. 1 kb of the S. griseus inserted DNA. These results, and those of studies in which Tn5 abolished the Pab+ phenotype by insertion in vivo in the tet promoter or downstream of it, indicated that the S. griseus pab promoter was not expressed in E. coli but that the pab gene could be expressed by transcriptional readthrough from the vector. Experiments in which the cloned DNA was transferred back from E. coli to S. lividans suggested, but did not prove, that the Streptomyces pab promoter had been deleted by loss of the approx. 1-kb segment. These experiments showed expression of both the tet (of pBR322) and kan (of Tn5) promoters in S. lividans.

Regulation by aromatic amino acids of the biosynthesis of candicidin by Streptomyces griseus

The biosynthesis by Streptomyces griseus of candicidin, an aromatic polyene macrolide antibiotic, was inhibited by L-tryptophan, L-phenylalanine and, to a lesser degree, by L-tyrosine. A mixture of the three aromatic amino acids inhibited candicidin biosynthesis to a greater extent than did each amino acid separately. L-Tryptophan strongly inhibited the incorporation of the labelled precursors propionate or 4-aminobenzoic acid into candicidin. Incorporation of propionate into candicidin was 50% inhibited by 2.5 mM-tryptophan. Inhibition by tryptophan did not require protein synthesis as the same effect was observed in cells in which protein synthesis was prevented by chloramphenicol. The inhibitory effect of L-tryptophan was partially reversed by exogenous 4-aminobenzoic acid suggesting that this effect is exerted at the level of 4-aminobenzoic acid synthase.

Estudio briológico de la Sierra del Torcal de Antequera (Málaga)

Se citan para el Torcal de Antequera setenta y siete especies de briófitos, de las cuales sesenta y ocho pertenecen a la clase Musci y nueve a la clase Hepaticae. Se citan por primera vez en Andalucía oriental: Radula lindbergiana Got. y Cololejeunea rossettiana (Mass.) Schiff, siendo la segunda localidad de Andalucía donde se cita Neckeradelphus menziesii (Hook.) Steere. Se realiza igualmente un estudio sociológico de las principales comunidades briofíticas de la zona, proponiendo como nuevas las asociaciones Neckeradelphetum menziesii y Cololejeuneo- Rhynchostegietum tenellae.