A distinct small RNA pathway silences selfish genetic elements in the germline

In the Drosophila germline, repeat-associated small interfering RNAs (rasiRNAs) ensure genomic stability by silencing endogenous selfish genetic elements such as retrotransposons and repetitive sequences. Whereas small interfering RNAs (siRNAs) derive from both the sense and antisense strands of their double-stranded RNA precursors, rasiRNAs arise mainly from the antisense strand. rasiRNA production appears not to require Dicer-1, which makes microRNAs (miRNAs), or Dicer-2, which makes siRNAs, and rasiRNAs lack the 2',3' hydroxy termini characteristic of animal siRNA and miRNA. Unlike siRNAs and miRNAs, rasiRNAs function through the Piwi, rather than the Ago, Argonaute protein subfamily. Our data suggest that rasiRNAs protect the fly germline through a silencing mechanism distinct from both the miRNA and RNA interference pathways.

Small non-coding RNAs and genomic imprinting

Experimental and computer-assisted approaches have led to the identification of hundreds of imprinted small RNA genes, mainly clustered in two chromosomal domains (human 15q11-->q13 and 14q32 loci). The genes are only detected in placental mammals and belong to the C/D RNA and microRNA gene families. These are small non-coding RNAs involved in RNA-guided post-transcriptional RNA modifications and RNA-mediated gene silencing, respectively. Here, we discuss their potential functions and report the identification of novel small RNA genes lying within (or nearby) known imprinted chromosomal domains.

Electromagnetic hypersensitivity (EHS) and subjective health complaints associated with electromagnetic fields of mobile phone communication--a literature review published between 2000 and 2004

Literature published between 2000 to 2004 concerning electromagnetic fields (EMF) of mobile communication and electromagnetic hypersensitivity (EHS) or unspecific symptoms of ill health, respectively, is reviewed. Basically, literature from established databases was systematically searched for. For each study, the design and quality were evaluated by means of a criteria list in order to judge evidence for causality of exposures on effects. Finally, 13 studies of sufficient quality were considered for this review. In only one provocation study, individuals with self-reported electromagnetic hypersensitivity were exposed to EMF. Their perception of field status was no better than would have been expected by chance. Results of five randomised cross-over studies on impaired well-being due to mobile phone exposure were contradictory. Even though these studies would allow more reliable exposure assessment, they are limited due to short exposure period and the small study size. No firm conclusion could be drawn from a few observational epidemiological studies finding a positive association between exposure and unspecific symptoms of ill health due to methodological limitations. Causality of exposure and effect was not derivable from these cross-sectional studies as field status and health complaints were assessed at the same time. In addition, exposure assessment has not been validated. In conclusion, based on the limited studies available, there is no valid evidence for an association between impaired well-being and exposure to mobile phone radiation presently. However, the limited quantity and quality of research in this area do not allow to exclude long-term health effects definitely.

Computer aided surgical reconstruction after complex facial burn injuries – opportunities and limitations

In severe facial burn injuries with extensive destruction of anatomical structures, cosmetic and functional outcome of treatment are frequently not satisfactory. Although operative therapy is being continuously refined, the variety and proximity of structures in the facial region is considered a major challenge in reconstructive surgery. We present the case of a 16-year-old patient with a severe facial burn injury. In planning the reconstructive procedures, we used a multimodal approach employing data from computerized tomography imaging, as well as from surface laser scanning, which provided three-dimensional visualization of facial soft tissues. Amount and pattern of structural loss could thus be determined more precisely and studied more vividly than by inspection of two-dimensional imaging alone. Anatomical features to be reconstructed could be projected onto the skin area of the prelaminated vertical rectus abdominis muscle (VRAM) flap that has been chosen to cover the defect. Prior to surgery, correction of the defects was simulated and the results of the virtual procedure superimposed on a three-dimensional head model of the patient. Tissue elasticity and thickness of the flap, however, could not be ascertained in advance, indicating the limitations of the method.

Imprinted small RNA genes

Genomic imprinting is an epigenetic phenomenon that results in differential expression of both alleles, depending on their parent of origin. We have recently identified many imprinted small non-coding RNA genes belonging to the C/D RNA and microRNA gene families, both of which are usually known to play key roles in post-transcriptional metabolism of specific genes (e.g. C/D RNAs guide ribose methylation of target RNAs while microRNAs elicit either translational repression or RNA interference). Although the functional and evolutionary significance of this association between C/D RNA genes, microRNA genes and genomic imprinting is still highly elusive, these observations provide a framework for further analysis of the potential role of small non-coding RNAs in epigenetic control.

A large imprinted microRNA gene cluster at the mouse Dlk1-Gtl2 domain

microRNAs (or miRNAs) are small noncoding RNAs (21 to 25 nucleotides) that are processed from longer hairpin RNA precursors and are believed to be involved in a wide range of developmental and cellular processes, by either repressing translation or triggering mRNA degradation (RNA interference). By using a computer-assisted approach, we have identified 46 potential miRNA genes located in the human imprinted 14q32 domain, 40 of which are organized as a large cluster. Although some of these clustered miRNA genes appear to be encoded by a single-copy DNA sequence, most of them are arranged in tandem arrays of closely related sequences. In the mouse, this miRNA gene cluster is conserved at the homologous distal 12 region. In vivo all the miRNAs that we have detected are expressed in the developing embryo (both in the head and in the trunk) and in the placenta, whereas in the adult their expression is mainly restricted to the brain. We also show that the miRNA genes are only expressed from the maternally inherited chromosome and that their imprinted expression is regulated by an intergenic germline-derived differentially methylated region (IG-DMR) located approximately 200 kb upstream from the miRNA cluster. The functions of these miRNAs, which seem only conserved in mammals, are discussed both in terms of epigenetic control and gene regulation during development.

Identification of 13 novel human modification guide RNAs

Members of the two expanding RNA subclasses termed C/D and H/ACA RNAs guide the 2'-O-methylations and pseudouridylations, respectively, of rRNA and spliceosomal RNAs (snRNAs). Here, we report on the identification of 13 novel human intron-encoded small RNAs (U94-U106) belonging to the two subclasses of modification guides. Seven of them are predicted to direct 2'-O-methylations in rRNA or snRNAs, while the remainder represent novel orphan RNA modification guides. From these, U100, which is exclusively detected in Cajal bodies (CBs), is predicted to direct modification of a U6 snRNA uridine, U(9), which to date has not been found to be pseudouridylated. Hence, within CBs, U100 might function in the folding pathway or other aspects of U6 snRNA metabolism rather than acting as a pseudouridylation guide. U106 C/D snoRNA might also possess an RNA chaperone activity only since its two conserved antisense elements match two rRNA sequences devoid of methylated nucleotides and located remarkably close to each other within the 18S rRNA secondary structure. Finally, we have identified a retrogene for U99 snoRNA located within an intron of the Siat5 gene, supporting the notion that retro-transposition events might have played a substantial role in the mobility and diversification of snoRNA genes during evolution.

Asymmetric regulation of imprinting on the maternal and paternal chromosomes at the Dlk1-Gtl2 imprinted cluster on mouse chromosome 12

Genomic imprinting causes parental origin-specific gene expression. Cis-acting regulatory elements that control imprinting are not fully understood but involve regions that become differentially methylated on the two parental chromosomes during male and female gametogenesis. Understanding properties of maternally and paternally inherited imprints provides insight into the mechanisms and evolution of genomic imprinting. Previously we identified an intergenic germline-derived differentially methylated region (IG-DMR) that is a candidate control element for an imprinted domain on distal mouse chromosome 12 (ref. 5). The 1-Mb cluster contains the paternally expressed protein-coding genes Dlk1 (refs. 6,7) and Dio3 (ref. 8,9) and several maternally expressed non-coding RNAs, including Gtl2 (refs. 6,7,10) and C/D snoRNAs. A retrotransposon-like gene (Rtl1) is expressed from the paternal chromosome and has an antisense transcript expressed from the maternal chromosome containing two microRNAs with full complementarity to Rtl1 (ref. 12). Here we show that deletion of the IG-DMR from the maternally inherited chromosome causes bidirectional loss of imprinting of all genes in the cluster. When the deletion is transmitted from the father, imprinting is unaltered. These results prove that the IG-DMR is a control element for all imprinted genes on the maternal chromosome only and indicate that the two parental chromosomes control allele-specific gene expression differently.

Imprinted microRNA genes transcribed antisense to a reciprocally imprinted retrotransposon-like gene

MicroRNAs (miRNAs) are an abundant class of RNAs that are approximately 21-25 nucleotides (nt) long, interact with mRNAs and trigger either translation repression or RNA cleavage (RNA interference, RNAi) depending on the degree of complementarity with their targets. Here we show that the imprinted mouse distal chromosome 12 locus encodes two miRNA genes expressed from the maternally inherited chromosome and antisense to a retrotransposon-like gene (Rtl1) expressed only from the paternal allele.

Fast generation of stereolithographic models

In this paper we present a work-in-progress method for fast and efficient generation of stereolithographic models. The overall approach is embedded in our general software framework Julius, which runs on high-end-graphic systems as well as on low-level PCs. The design of the support structures needed for the stereolithographic process will allow semiautomatic generation of the model. We did produce support structures for stereolithographic models with this fast data processing pipeline and will show future perspectives in this paper.

Identification of tandemly-repeated C/D snoRNA genes at the imprinted human 14q32 domain reminiscent of those at the Prader-Willi/Angelman syndrome region

A human imprinted domain at 14q32 contains two co-expressed and reciprocally imprinted genes, DLK1 and GTL2, which are expressed from the paternally and maternally inherited alleles, respectively. We have previously shown that another imprinted locus, on human 15q11-q13, contains a large number of tandemly repeated C/D small nucleolar RNA genes (or C/D snoRNAs) only expressed from the paternal allele. Here we show that the region downstream from the GTL2 gene is also characterized by a transcription unit spanning many repeated intron-encoded C/D snoRNA genes, most of them arranged into two tandem arrays of 31 and 9 copies. Intriguingly, these snoRNAs depart from previously reported rRNA or snRNA methylation guides by their tissue-specific expression and by their lack of complementarity to rRNA or snRNA within their sequences. Analysis of the orthologous region in the mouse shows that the previously reported maternally expressed Rian gene, located downstream of Gtl2 on the distal 12 chromosome, encodes at least nine C/D snoRNAs. Through a systematic search in rodents, we could identify other C/D snoRNA genes in this domain. All snoRNAs identified on mouse distal 12 are brain-specific and only expressed from the maternally inherited allele. The human imprinted 14q32 domain therefore shares common genomic features with the imprinted 15q11-q13 loci. This link between tandemly repeated C/D snoRNA genes and genomic imprinting suggests a role for these snoRNAs and/or their host non-coding RNA genes in the evolution and/or mechanism of the epigenetic imprinting process.

A hybrid bacterial replication origin

We constructed a hybrid replication origin that consists of the main part of oriC from Escherichia coli, the DnaA box region and the AT-rich region from Bacillus subtilis oriC. The AT-rich region could be unwound by E. coli DnaA protein, and the DnaB helicase was loaded into the single-stranded bubble. The results show that species specificity, i.e. which DnaA protein can do the unwinding, resides within the DnaA box region of oriC.

Parvovirus B19 DNA in plasma pools and plasma derivatives

BACKGROUND AND OBJECTIVES

Human parvovirus B19 (B19) has been transmitted by various plasma-derived medicinal products. The aim of this study was to determine the frequency and the level of B19 DNA contamination in plasma pools destined for fractionation and in a broad range of plasma derivatives. In addition, removal of B19 DNA by the manufacturing process was investigated in cases where corresponding samples from plasma pool and product were available.

MATERIALS AND METHODS

Plasma pool samples and blood products were tested for B19 DNA by nested polymerase chain reaction (PCR), and the viral DNA content was determined by TaqMan quantitative PCR.

RESULTS

Two-hundred and twenty two of 372 plasma pools for fractionation contained B19 DNA at concentrations of 10(2)-10(8) genome equivalents/ml (geq/ml). While approximately 65% of the DNA-positive plasma pools were only moderately contaminated (< 10(5) geq/ml), 35% contained > 10(6) geq/ml. High frequencies of contamination were detected in Factor VIII (79 of 91), prothrombin complex concentrates (38 of 43) and Factor IX (41 of 62), where the concentration of B19 DNA ranged between 102 and 107 geq/ml. A lower level of B19 DNA contamination was found in antithrombin III (five of 26 samples), in anti-D immunoglobulins (three of 37 samples) and in albumin (four of 51 samples), with levels ranging between 10(2) and 10(3) geq/ml. Furthermore, investigation of plasma pools for solvent/detergent plasma (S/D plasma), from two manufacturers, revealed B19 DNA in 15 of 66 batches at concentrations of 10(2)-10(8) geq/ml. Similar concentrations were detected in the corresponding final S/D plasma products. Anti-B19 immunoglobulin G (IgG) was found in plasma pools and S/D plasma at concentrations of approximately 40 IU/ml.

CONCLUSION

Although positive PCR results do not necessarily reflect infectivity, these data show that B19 is a common contaminant in plasma pools and in plasma-derived medicinal products. Considering the resistance of animal parvoviruses to inactivation by heat and chemical agents, and the absence of specific information for B19, the risk of B19 transmission by plasma products should be considered. Physicians should be aware of this problem when treating patients of B19-related risk groups. The plasma fractionation industry should continue their efforts to avoid B19 contamination of plasma derivatives and develop methods which are effective in removing/inactivating parvovirus B19.

The diagnostic dilemma of traumatic rupture of the diaphragm

BACKGROUND

Traumatic rupture of diaphragm is caused by blunt or penetrating trauma. Early diagnosis is difficult, and complications such as visceral herniation may arise. A 10-year evaluation of all diagnostic procedures used in patients with surgically proved traumatic rupture of the diaphragm is presented.

METHODS

A review of all patients with surgically proved diaphragmatic injury from 1988 to 1998 was conducted. All diagnostic methods were analyzed in terms of their ability to identify diaphragmatic rupture.

RESULTS

During the study period, 31 patients with a mean age of 34 years were treated. Of these patients, 20 sustained blunt trauma and 11 experienced penetrating trauma. The initial chest x-ray was diagnostic for 6 of the 31 patients, nonspecific for 15 of the patients, and normal for 10 of the patients. In no case was sonography diagnostic. Thoracoabdominal computed tomography (CT), performed in 22 of the patients, led to diagnosis for 5 patients and unspecific findings for 17 patients. Statistical analyses showed no significant difference between initial chest x-ray and thoracoabdominal CT. No significant difference between blunt or penetrating trauma or between left-side and right-side ruptures could be recognized with any diagnostic tool.

CONCLUSIONS

All the diagnostic methods investigated in this study showed unsatisfying results, and traumatic rupture of the diaphragm seems to remain a diagnostic dilemma. Endoscopic techniques not tested in this study and discussed controversially may offer a good chance for early diagnosis and repair of the injured diaphragm.

Bacterial replication initiator DnaA. Rules for DnaA binding and roles of DnaA in origin unwinding and helicase loading

We review the processes leading to the structural modifications required for the initiation of replication in Escherichia coli, the conversion of the initial complex to the open complex, loading of helicase, and the assembly of two replication forks. Rules for the binding of DnaA to its binding sites are derived, and the properties of ATP-DnaA are described. We provide new data on cooperative interaction and dimerization of DnaA proteins of E. coli, Streptomyces and Thermus thermophilus, and on the stoichiometry of DnaA-oriC complexes of E. coli.

Giant-cell tumor of the synovial membrane: localized nodular synovitis in the knee joint

Giant-cell tumor of the synovia is a benign neoplasm characterized histologically by proliferating histiocytes bearing lipids and hemosiderin intermingled with a variable number of multinuclear giant cells. Areas of predilection are the hand, and in the case of synovial joints, the knee joint is particularly affected. Clinically, patients have signs of mechanical derangement and, with the knee joint, meniscal symptoms and locking are often present. Joint effusion without previous trauma is another typical finding. Diagnosis is carried out by radiographic tools and has to be confirmed histologically. Giant-cell tumor of the synovia is treated by local excision either by arthroscopy or by arthrotomy. To our knowledge, the case we present is the largest giant-cell tumor of the synovia in the knee joint ever described in literature.

Distal femoral fracture through the screw hole of a ligament augmentation device fixation

SUMMARY

Complications associated with fixation of artificial ligaments in augmented repair of the anterior cruciate ligament (ACL) have been reported throughout the literature. However, fractures following ligament augmentation device (LAD) fixation appear to be rare. We report the case of a 43-year-old woman, injured in a road accident, who sustained a depressed fracture of the tibial plateau and knee instability. The fracture was reduced and the medial collateral ligament and the menisci were sutured. The torn ACL was repaired using the Marshall technique and augmented with an LAD in an over-the-top technique. Twenty-five months postoperatively, the patient sustained a distal femoral fracture through the screw hole of the former LAD fixation after a simple fall on the street.

The interaction domains of the DnaA and DnaB replication proteins of Escherichia coli

The initiation of chromosome replication in Escherichia coli requires the recruitment of the replicative helicase DnaB from the DnaBC complex to the unwound region within the replication origin oriC, supported by the oriC-bound initiator protein DnaA. We defined physical contacts between DnaA and DnaB that involve residues 24-86 and 130-148 of DnaA and residues 154-210 and 1-156 of DnaB respectively. We propose that contacts between DnaA and DnaB occur via two interaction sites on each of the proteins. Interaction domain 24-86 of DnaA overlaps with its N-terminal homo-oligomerization domain (residues 1-86). Interaction domain 154-210 of DnaB overlaps or is contiguous with the domains known to interact with plasmid initiator proteins. Loading of the DnaBC helicase in vivo can only be performed by DnaA derivatives containing (in addition to residues 24-86 and the DNA-binding domain 4) a structurally intact domain 3. Nucleotide binding by domain 3 is, however, not required. The parts of DnaA required for replication of pSC101 were clearly different from those used for helicase loading. Domains 1 and 4 of DnaA, but not domain 3, were found to be involved in the maintenance of plasmid pSC101.

Binding of human lipoproteins (low, very low, high density lipoproteins) to recombinant envelope proteins of hepatitis C virus

Heterogeneities in the density of hepatitis C virus (HCV)-RNA-carrying material from human sera (1.03-1.20 g/ml) are partially due to the binding of lipoproteins [low density (LDL), very low density (VLDL), high density (HDL) lipoproteins] and immunoglobulins. In this study we demonstrate the binding of recombinant HCV envelope protein (El/E2) to human LDL, VLDL and HDL on a molecular basis. The binding of lipoproteins was restricted to the middle part of the El gene product (amino acids 222-336) and the C-terminal part of the E2 protein (amino acids 523-809). Lipoproteins did not bind to recombinant HCV core protein.

Is stage conversion the initiating event for reactivation of Toxoplasma gondii in brain tissue of AIDS patients?

Reactivation of chronic toxoplasmosis resulting in Toxoplasma encephalitis (TE) is a common event in acquired immune deficiency syndrome (AIDS) patients. Conversion from Toxoplasma gondii bradyzoites to tachyzoites is a prerequisite for reactivation. Until recently, the study of stage conversion in human tissue was not possible due to the lack of antibodies that recognize stage-specific epitopes after long-term formaldehyde fixation. Using the combination of a polyclonal anti-T. gondii antibody, the cyst-stage-specific monoclonal antibody CC2, and a tachyzoite-specific polyclonal antibody (anti-SAG1, recombinant), we tried to demonstrate parasite differentiation in the brain tissue of 10 AIDS patients with clinically suspected TE. Double labeling of the stage-specific antibodies enabled us to demonstrate interconversion between tachyzoites and bradyzoites for the first time in human tissue. The study confirmed that the transformation process is nonsynchronous and that the manifestation of TE depends on the degree and site of tissue destruction caused by invading tachyzoites. The original source of tachyzoites could never be located, but a few samples suggested that tachyzoites may invade by dissemination across the blood-brain barrier. Cyst rupture as the first event in the process of reactivation was not seen. We conclude that the initial site(s) of reactivation will be destroyed by tissue-destructive tachyzoites long before clinical symptoms occur.

Timing of developmentally programmed excision and circularization of Paramecium internal eliminated sequences

Paramecium internal eliminated sequences (IESs) are short AT-rich DNA elements that are precisely eliminated from the germ line genome during development of the somatic macronucleus. They are flanked by one 5'-TA-3' dinucleotide on each side, a single copy of which remains at the donor site after excision. The timing of their excision was examined in synchronized conjugating cells by quantitative PCR. Significant amplification of the germ line genome was observed prior to IES excision, which starts 12 to 14 h after initiation of conjugation and extends over a 2- to 4-h period. Following excision, two IESs were shown to form extrachromosomal circles that can be readily detected on Southern blots of genomic DNA from cells undergoing macronuclear development. On these circular molecules, covalently joined IES ends are separated by one copy of the flanking 5'-TA-3' repeat. The similar structures of the junctions formed on the excised and donor molecules point to a central role for this dinucleotide in IES excision.

The mycosubtilin synthetase of Bacillus subtilis ATCC6633: a multifunctional hybrid between a peptide synthetase, an amino transferase, and a fatty acid synthase

Bacillus subtilis strain ATCC6633 has been identified as a producer of mycosubtilin, a potent antifungal peptide antibiotic. Mycosubtilin, which belongs to the iturin family of lipopeptide antibiotics, is characterized by a beta-amino fatty acid moiety linked to the circular heptapeptide Asn-Tyr-Asn-Gln-Pro-Ser-Asn, with the second, third, and sixth position present in the D-configuration. The gene cluster from B. subtilis ATCC6633 specifying the biosynthesis of mycosubtilin was identified. The putative operon spans 38 kb and consists of four ORFs, designated fenF, mycA, mycB, and mycC, with strong homologies to the family of peptide synthetases. Biochemical characterization showed that MycB specifically adenylates tyrosine, as expected for mycosubtilin synthetase, and insertional mutagenesis of the operon resulted in a mycosubtilin-negative phenotype. The mycosubtilin synthetase reveals features unique for peptide synthetases as well as for fatty acid synthases: (i) The mycosubtilin synthase subunit A (MycA) combines functional domains derived from peptide synthetases, amino transferases, and fatty acid synthases. MycA represents the first example of a natural hybrid between these enzyme families. (ii) The organization of the synthetase subunits deviates from that commonly found in peptide synthetases. On the basis of the described characteristics of the mycosubtilin synthetase, we present a model for the biosynthesis of iturin lipopeptide antibiotics. Comparison of the sequences flanking the mycosubtilin operon of B. subtilis ATCC6633, with the complete genome sequence of B. subtilis strain 168 indicates that the fengycin and mycosubtilin lipopeptide synthetase operons are exchanged between the two B. subtilis strains.

The N-terminus promotes oligomerization of the Escherichia coli initiator protein DnaA

Initiation of chromosome replication in Escherichia coli is governed by the interaction of the initiator protein DnaA with the replication origin oriC. Here we present evidence that homo-oligomerization of DnaA via its N-terminus (amino acid residues 1-86) is also essential for initiation. Results from solid-phase protein-binding assays indicate that residues 1-86 (or 1-77) of DnaA are necessary and sufficient for self interaction. Using a 'one-hybrid-system' we found that the DnaA N-terminus can functionally replace the dimerization domain of coliphage lambda cl repressor: a lambdacl-DnaA chimeric protein inhibits lambda plasmid replication as efficiently as lambdacI repressor. DnaA derivatives with deletions in the N-terminus are incapable of supporting chromosome replication from oriC, and, conversely, overexpression of the DnaA N-terminus inhibits initiation in vivo. Together, these results indicate that (i) oligomerization of DnaA N-termini is essential for protein function during initiation, and (ii) oligomerization does not require intramolecular cross-talk with the nucleotide-binding domain III or the DNA-binding domain IV. We propose that E. coli DnaA is composed of largely independent domains - or modules - each contributing a partial, though essential, function to the proper functioning of the 'holoprotein'.

Functional domains of DnaA proteins

Functional domains of the initiator protein DnaA of Escherichia coli have been defined. Domain 1, amino acids 1-86, is involved in oligomerization and in interaction with DnaB. Domain 2, aa 87-134, constitutes a flexible loop. Domain 3, aa 135-373, contains the binding site for ATP or ADP, the ATPase function, a second interaction site with DnaB, and is required for local DNA unwinding. Domain 4 is required and sufficient for specific binding to DNA. We show that there are three different types of cooperative interactions during the DNA binding of DnaA proteins from E. coli, Streptomyces lividans, and Thermus thermophilus: i) binding to distant binding sites; ii) binding to closely spaced binding sites; and iii) binding to non-canonical binding sites.

[Ethylene glycol poisoning and brain injury--a dangerous combination]

We report on a patient after brain injury additionally showing signs of ethylene glycol intoxication. CT-scan showed a subdural hematoma, which in spite of increasing neurological deficit didn't show any enlargement. Metabolic acidosis with an increased anion gap and osmolar gap led to the diagnosis of ethylene glycol intoxication. Then intensive hemodialysis and i.v. ethanol were administered and the intoxication could be treated successfully.

Comparison of femoral and tibial pullout forces in bone-patellar tendon-bone anterior cruciate ligament reconstructions with a new interference fixation device

Interference screws have become the standard method for fixing bone-patellar tendon-bone (BPTB) grafts. To avoid the inherent pitfalls and complications of interference screws, a 28-mm long and from 5 to 7 mm spreadable metal bolt with nontapping threads was developed for this study. The technical applicability and biomechanical characteristics of this new BPTB interference fixation device were investigated by dissection or tensile testing of 48 cadaveric knee specimens from young donors. No problems occurred with respect to bone plug anchoring during insertion of the spreading bolts. The clinically important linear load was 920+/-283 N for the femoral and 635+/-247 N for the tibial fixation site. Bone plug pullout was the mode of failure in all specimens. The results of this study indicate that the spreading bolt is a reasonable alternative to interference screws.

Acetabular fractures: operative management and long term results

INTRODUCTION

While the undisplaced acetabular fractures have a good prognosis after conservative treatment, the management of the displaced fractures has been a controversial issue over the last decades with variable results in their treatment and prognosis. Anatomical reduction can be only achieved operatively. The long term outcome of 209 patients with displaced acetabular fractures treated by open reduction and internal fixation was presented.

MATERIAL AND METHODS

Between 1972 and 1996, 209 patients with a mean age of 38 years (15-62a) were treated for displaced acetabular fractures operatively. 161 patients could be followed up over a period of 2 to 20 years. The function of the hip joint in correlation with radiological results was evaluated according to the scheme of Merle d'Aubinge.

RESULTS

Patients with single column fractures showed 90% good or excellent results followed by 55% good or excellent results in patients with transverse fractures. The highest rates of complication (20% osteoarthritis, 6% femoral head necrosis, 9% heterotopic ossification) were observed in both column fractures and in transverse and posterior wall fractures. Deep infection was observed in 6 cases (4%), superficial wound infection in 8 cases (5%). Primary sciatic nerve palsy was seen in 10 cases (6%) and postoperative peroneal nerve palsy in 6 cases (4%), all of which improved during the rehabilitation period.

CONCLUSION

Displaced acetabular fractures of the weight bearing part of the dome, i.e. transtectal fractures, should be treated operatively. The operation should preferably be performed within one week after the injury.

[Concomitant intra-abdominal injuries in pelvic trauma]

A pelvic fracture combined with abdominal injury and soft tissue damage, defined as complex pelvic trauma, is an expression of severe trauma and requires specific procedures in terms of diagnosis and treatment. The clinical course and outcome of 75 patients (56 males and 19 females) with complex pelvic injuries from 1985 to 1996 are presented in this follow-up study. There were 33 (44%) Type A (stable pelvic ring fracture), 10 (13%) Type B (rotationally unstable pelvic ring fracture) and 32 (43%) Type C (rotationally and vertically unstable pelvic ring fracture). Concomitant abdominal injuries included: 14 liver lacerations (19%), 28 splenic lesions (37%), 7 ruptures of the kidney (9%), 18 ruptures of the bladder (24%), 13 urethra lesions (17%), 13 intestinal lesions (17%) and 16 ruptures of the diaphragm (21%). The mean Hannover polytrauma score was 22 points. Twelve patients (16%) died within 6 hours after associated head and/or chest injury with hemorrhage, and 3 patients (4%) died in the intensive care unit from sepsis and multiorgan failure within 2 weeks after injury. The priority of the steps taken is of utmost importance in the diagnosis and treatment of such injuries. Immediate control of hemorrhage by surgical or minimally invasive radiological techniques, stabilization of pelvic fractures and inter-disciplinary cooperation are important requirements for management and successful treatment.

Biocompatibility of polyethylene terephthalate (Trevira hochfest) augmentation device in repair of the anterior cruciate ligament

The biocompatibility of a 3 mm band made of polyethylene terephthalate (Trevira hochfest) has been tested in an experimental study within right knee joints of 60 sheep. After transsecting the anterior cruciate ligament (ACL), two randomized groups were formed. In group I, the ACL was repaired according to the Marshall technique whilst in group II an additional 3 mm polyethylene terephthalate (PET) augmentation band was implanted using the through-the-condyle (TTC) procedure. To assess the biocompatibility of the augmentation device the knee joints of both groups were punctured and the synovial fluids were analyzed before, as well as 2, 6, 16, 26, and 52 weeks after the operation. In addition, the histologic appearance of excised suprapatellar pouches and ipsilateral inguinal and popliteal lymphatic noduli were examined. Comparing both groups no significant differences were found neither before nor after the augmented and non-augmented ACL repair. No pathological increase in the total protein concentration occurred after operation and no significant differences versus the preoperative analysis were found. No synovitis signalling a decrease in the glucose concentration was observed. The cytological examination revealed no increase of the leukocyte cell count results. Within the synovial specimen neither free nor phagocytosed PET wearparticles could be detected. In groups I and II the histological appearance of excised popliteal and inguinal lymphatic noduli showed a normal result. In 25% of the PET augmented ACL repairs, a slight concentration of PET wearparticles and solitary, multinuclear giant foreign body cells could be seen in the histological preparations of suprapatellar pouches.

Tibial avulsion fracture of the posterior cruciate ligament: K-wire or screw fixation? A retrospective study of 26 patients

Although the posterior cruciate ligament (PCL) is not frequently injured, a greater understanding of its role in stabilizing the knee joint, mechanism of injury and treatment has developed. Isolated avulsion injuries constitute only a subgroup of PCL injuries, but nevertheless several operative techniques have been described for the fixation of the avulsed bony fragment. In order to investigate whether K-wire or screw fixation yields better long-term results, we examined 26 patients at an average of 10.5 years after the initial operation. Clinical examination, activity level, radiographic evaluation and instrumented measurements did not reveal any significant differences. All the patients had an excellent functional result. Thus, both K-wire and screw fixation are recommended for bony PCL avulsion injuries.

Vascular anatomy of the ovine anterior cruciate ligament. A macroscopic, histological and radiographic study

Sheep are being extensively utilized in animal models for orthopaedic research, but the vascular anatomy of their anterior cruciate ligament (ACL) has not yet been thoroughly described. This study demonstrates the blood supply to the ACL. Vascular injection with plastogen G, lead oxide and India ink was performed in 12 back limbs of Styrian mountain sheep, and gross observations, microradiography and routine histology were done. The large vessel and the microvascular anatomy are similar to those described for humans. The middle genicular artery and the descending genicular artery contribute vessels that supply the ACL. Epiligamentous vascular plexuses give off capillaries which penetrate the ligament substance and supply numerous, longitudinally oriented intraligamentous vessels. These findings make the Styrian mountain sheep a potential animal model for biologic investigations of ACL pathology.

Load sharing in augmented anterior cruciate ligament repair: a mathematical analysis based on in vitro measurements

OBJECTIVE: To quantify the stress on a reinserted anterior cruciate ligament (ACL) we studied the load sharing between the ACL and a 3.7 mm polyethylene terephthalate (PET) band in 10 knees of fresh human cadavers. DESIGN: The load sharing between the Marshall sutures-ACL complex and the PET band and between the ACL and the PET band was calculated by means of a mathematical model. BACKGROUND: Augmentation of a reinserted ACL with a synthetic band is an accepted treatment for a ruptured ACL. METHODS: After transsecting the ACL at its femoral origin and reinserting it with four sutures using the Marshall technique we augmented it with the PET band. The augmentation device was inserted by the through-the-condyle (TTC) procedure and attached without preload to the femoral and the tibial condyle with 4 mm staples. Then the length of the ACL, the lengths of the Marshall sutures, the partial lengths and the angles between the different directions, and the adherence-friction force of the PET band were measured. RESULTS: In the beginning the Marshall sutures-ACL complex takes over 40% of an externally applied load and the PET band 60%. After the hypothetical ACL healing phase the PET band takes over 27% and the ACL 73% of the load. CONCLUSIONS: An external force of 40 N acting on the knee will therefore lead to an elongation of the Marshall sutures-ACL complex and result in movement of the proximal end of the ACL away from the femoral condyle of at least 0.5 mm, which is highly undesirable in the early postoperative healing phase.

[Meniscus lesions after isolated anterior cruciate ligament rupture]

In this retrospective study the meniscal status of 34 patients with untreated complete anterior cruciate ligament (ACL) tears is reported. The anterior cruciate ligament injury was initially documented by examination under anesthesia and arthroscopy. Treatment in all cases consisted of a standard protocol of early rehabilitation and bracing. The mean follow-up was 7.3 years. Twenty-two (65%) patients showed signs of meniscal pathology at an average of 2.5 years after the ACL injury during the follow-up period. Rearthroscopy was performed and showed a higher incidence of medial meniscus tears (53%) than lesions of the lateral meniscus (41%). The most common tear of the medial meniscus was the bucket-handle type, followed by the flap tear and the single longitudinal split of the posterior horn. Secondary reconstruction of the ACL was necessary in 18 patients (82%) complaining of symptoms indicative of permanent anterior instability of the knee. The remaining 4 patients had rearthroscopy 3.5 years after the ACL injury and a partial meniscectomy and ACL reconstruction was performed. 12 patients (35%) had no symptoms or signs of joint instability or meniscal pathology during the follow-up period, but discontinued their sporting activities. This study indicates the increasing incidence of meniscal tears during ACL insufficiency. We recommend that patients with ruptures of the anterior cruciate ligament should be investigated for meniscal tears and that early ligament reconstruction of the knee and meniscal repair or partial meniscectomy should be considered simultaneously.

Changes in cardiac signal transduction systems in chronic ethanol treatment preceding the development of alcoholic cardiomyopathy

Chronic alcohol consumption has been postulated as an important pathogenetic mechanism for the development of alcoholic cardiomyopathy. This form of chronic heart failure shares with other forms of cardiomyopathy the pronounced alterations of the adrenergic signal transduction systems. These alterations include a significant reduction of beta-adrenergic receptors and a reduced responsiveness of the adenylyl cyclase. Changes of other receptor systems such as alpha-adrenergic and muscarinic receptors have not been studied extensively so far. To address the question if changes of the adrenergic signal transduction systems may occur early in the development of alcoholic cardiomyopathy and if alpha 1-adrenergic receptors and muscarinic receptors may be subjected to an altered expression even before severe impairment of the left ventricular function becomes obvious, rats were chronically fed with an alcohol diet containing 35% of total calorie intake as ethanol. In cardiac plasma membranes beta-adrenergic receptors, alpha 1-adrenergic receptors, muscarinic receptors and adenylyl cyclase activities were determined after 4 and 8 weeks of chronic alcohol treatment. After these periods of chronic alcohol diet no signs of overt heart failure such as pleural effusion or increased lung wet weight as parameters for congestion were present. Body weight gain was comparable in the controls and under chronic alcohol treatment in these adolescent rats. Both after 4 and 8 weeks of chronic alcohol treatment the density of cardiac beta-adrenergic receptors remained unchanged and all adenylyl cyclase activities remained fully responsive. In contrast, after 8 weeks of alcohol treatment the developmental increase of cardiac muscarinic receptors in the adolescent rats was greatly impaired resulting in a significantly reduced expression of these receptors even before clinical signs of heart failure. In contrast the density of cardiac alpha 1-adrenergic receptors were significantly reduced already after 4 weeks of chronic alcohol treatment with an additional impairment of the developmental increase after 8 weeks of alcohol treatment. These data characterize for the first time early changes of cardiac receptor system in chronic alcohol treatment which precede the development of overt heart failure. These changes include alpha 1-adrenergic and muscarinic receptors, but in contrast to severe heart failure, leave the beta 1-adrenergic system and the responsiveness of the adenylyl cyclase intact. Additionally these data show the developmentally increased expression of cardiac alpha 1-adrenergic and muscarinic receptors in rat heart.

Anterior instability of the knee despite an intensive rehabilitation program

To investigate if an intensive rehabilitation program has a positive influence on the late course of an old, isolated anterior cruciate ligament rupture, patients were evaluated at an average of 8 years after injury. Seventy-five percent had acquired the injury during sporting activities. After diagnostic arthroscopy, which was done at an average of 163 days after the injury, the patients immediately were assigned to an intensive rehabilitation program. At the followup examination, none of the patients had an excellent result as determined by the Swiss Knee Group Score; 6 patients had a good result; 13 had a fair result; and 8 had a bad result. Fourteen patients had a partial meniscectomy during the followup period, and 4 had positive signs for meniscal lesions at the followup examination. In 52% of the patients gonarthrosis had advanced 2 stages, and in 26% it had advanced 3 stages. There was a significant correlation between worsening of gonarthrosis and previous meniscectomy, poor evaluation scores, and clinical signs of instability. Even an intensive rehabilitation program cannot prevent secondary lesions of the meniscus with ensuing joint degeneration. Thus, immediate operative reconstruction of old ruptured anterior cruciate ligaments is recommended.

[Borderline indications for locked intramedullary nailing of femur and tibia]

The borderline indications of locked intramedullary nailing of the femur and the tibia, based on Küntscher nailing, are defined by the location of the fracture, the associated soft tissue injury, the appearance of infection and the patient's pulmonary status. From 1975 to 1995 at the Department of Traumatology, Vienna University School of Medicine, 551 patients with 559 femoral fractures and 536 patients with 548 tibial fractures were stabilized using locked intramedullary nailing. A total of 135 (24%) proximal femoral fractures were stabilized using intramedullary locking nails in 54 cases, and using long gamma nails in 81 cases. Ninety-one distal femoral fractures (16%) were stabilized in 82 cases with intramedullary locking nails and in 9 cases using retrograde nailing. In open fractures predominantly a reamed technique was used. Fifty-two of these fractures were femoral fractures and 101 were tibial fractures. Seventy-two femoral fractures (13%) were associated with compromised pulmonary function and polytrauma. Procedural changes from external fixation to the intramedullary locking nail technique were performed in 21 cases of femoral fractures and in 21 cases of tibial fractures. Six tibial fractures diagnosed as having compartment syndrome were treated using unreamed nailing and fasciotomy. The overall infection rate of femoral fractures was 1.7% and 1.9% for all tibial fractures; the nonunion rate of both femoral and tibial fractures was 0.5%. Because of the success rate observed in the treatment of borderline indications for locked intramedullary nailing of femoral and tibial fractures and the improvement in equipment, training and techniques, we have expanded the indications for treatment of these fractures by intramedullary nailing.

[Biocompatibility of polyethylene terephthalate--PET--(Trevira strong)--an in vivo study of the sheep knee]

The anterior cruciate ligament was transected at the femoral origin in the right stifle joint of 25 sheep. The ligaments were re-inserted using the Marshall technique, and reinforced with a 3 mm band made of polyethylene terephthalate--PET--(Trevira hochfest) using the through-the-condyle (TTC) procedure, and re-attached--with a preload of 20 N--to the femoral and tibial condyle with two 4 mm staples. To assess the biocompatibility of the augmentation band, the synovial fluid was analysed for total protein and glucose concentration 2, 6, 24, and 56 weeks after implantation, and a total and differential cell count performed. No significant differences were found before and after implantation of the PET band. No pathological increase in the total protein concentration occurred after implantation (normal range: > 3.0 g/dl), and no significant differences vs. the preoperative analysis were found. No synovitis-signalling decrease in the glucose concentration (normal range: > 40 mg/dl) was observed. The preoperative glucose concentration of 87 +/- 12.84 mg/dl showed no significant difference from the postoperative concentration of 95 +/- 13.58 mg/dl. The cytological examination revealed no increase in the leucocyte counts (normal range: 3 leucocytes/HPF). Neither free nor phagocytosed wear particles were seen.

Capture and RT-PCR of hepatitis C virus RNA with safety primers

The principle and practice of the polymerase chain reaction (PCR) has had a major impact on medical research. This is a powerful method but it does have its limitations, especially for clinical diagnostic work. We describe some improvements of hepatitis C virus (HCV) amplification such as simplification of specimen preparation, elimination of false negative reactions influenced by point mutations, and fluorimetric detection. The aim of the method is to make the procedure as easy and as inexpensive as possible for routine laboratories and for blood screening. After rapid chemical denaturation of the clinical specimen with guanidine thiocyanate and simultaneous hybridization of biotinylated primers to template HCV RNA, the product was fixed to streptavidin-coated magnetic beads and potential inhibitors were removed in easy washing steps. To eliminate the influence of point mutations within the primer binding sites, primer sets with different lengths at their 3'-end were developed for capture, reverse transcription, and amplification of genomic fragments by PCR. Positive results were identified by fluorescence staining. The low cost of the method allows the quantitation of templates by testing of dilution series as is common in microbiological laboratories.

[A simple method for removal of percutaneous endoscopically implanted gastrostomy tubes]

Percutaneous endoscopic gastrostomy (PEG) has become an accepted technique for providing longterm enteral nutrition. So far the PEG tubes have been removed by a second gastroscopy procedure. Extrusion of the PEG tube and fistula formation have been described as unusual complications. We report about 26 patients with severe brain injuries whose PEG tubes were removed percutaneously by applying constant traction force to the tubes. The soft internal bolsters collapsed and the PEG tubes could be pulled out through the gastrostomy site within 5-7 days. The gastrocutaneous fistulae closed spontaneously within 4 days. In one patient the internal bolster got caught in the external layer of the rectus muscle sheath and had to be removed through a small incision. There were no other complications and 21 patients rated their well-being as unimpaired. Thus we believe the "traction procedure" to be a simple, safe and cost-effective alternative to endoscopic removal of PEG catheters.

[Primary therapy refractory osteomyelitis of the sternum after aortocoronary bypass operation--a case report]

Osteomyelitis after median sternotomy for aortocoronary bypass operation is seen in 0.9%-2.1% of the cases described in the literature. Aetiology as well as adequate therapy are still in discussion. One case of foreign body induced osteomyelitis (pace maker electrode) with a therapy resistant osteomyelitis is presented and discussed in this paper.

[Alloplastic augmented femoral reinserted anterior cruciate liganent. Value of 2 channel augmentation for postoperative rehabilitation]

The rupture of the anterior cruciate ligament (ACL) near its femoral origin is a common injury of the knee and can lead to lesions of the meniscus due to instability and to early gonarthrosis. One procedure applied in current orthopaedic practice to prevent such impairment of knee joint function is ACL repair reinforced with a synthetic intraarticular ligament. In this study we used twelve knees of cadavers and after sectioning the ACL in each repaired it according the Marshall technique with USP 1 PDS II sutures. We augmented the repair in each case with a 3-mm PET (Trevira hochfest) band inserted by the through-the-condyle (TTC) procedure and attached without preload to the femoral and tibial condyle with a 4-mm staple. We then measured the length of the ACL, the length of the Marshall sutures-ACL complex, the partial lengths, and the deviation angles and adherence-friction force of the 3-mm PET augmentation device, and applied the law of Hooke to calculate the load-sharing between the USP 1 PDS II sutures-ACL complex and the 3-mm PET band and between the ACL and the 3-mm PET band, respectively. We also evaluated the load on the femoral and the tibial fixation of the augmentation device. The results showed that the 3-mm PET band took over 60% of an externally applied load on the knee during the hypothetic period of ACL healing and 27% of the force acting on the knee thereafter. It was calculated that a maximum of 75% of the load taken over by the augmentation device was at the tibial staple and only up to 45% of the force at the femoral one. With due consideration for the requirement for absolute protection ("stress shielding") of the healing ACL but also for the aim of early postoperative accelerated functional rehabilitation without casts, splints or other restrictions of joint movement, we believe that a pretensioned 3-mm PET band is the best choice, since augmentation without preload cannot fulfil these requirements.

Purification and Characterization of Hydroxyquinol 1,2-Dioxygenase from Azotobacter sp. Strain GP1

Hydroxyquinol 1,2-dioxygenase was purified from cells of the soil bacterium Azotobacter sp. strain GP1 grown with 2,4,6-trichlorophenol as the sole source of carbon. The presumable function of this dioxygenase enzyme in the degradative pathway of 2,4,6-trichlorophenol is discussed. The enzyme was highly specific for 6-chlorohydroxyquinol (6-chloro-1,2,4-trihydroxybenzene) and hydroxyquinol (1,2,4-trihydroxybenzene) and was found to perform ortho cleavage of the hydroxyquinol compounds, yielding chloromaleylacetate and maleylacetate, respectively. With the conversion of 1 mol of 6-chlorohydroxyquinol, the consumption of 1 mol of O(inf2) and the formation of 1 mol of chloromaleylacetate were observed. Catechol was not accepted as a substrate. The enzyme has to be induced, and no activity was found in cells grown on succinate. The molecular weight of native hydroxyquinol 1,2-dioxygenase was estimated to 58,000, with a sedimentation coefficient of 4.32. The subunit molecular weight of 34,250 indicates a dimeric structure of the dioxygenase enzyme. The addition of Fe(sup2+) ions significantly activated enzyme activity, and metal-chelating agents inhibited it. Electron paramagnetic resonance data are consistent with high-spin iron(III) in a rhombic environment. The NH(inf2)-terminal amino acid sequence was determined for up to 40 amino acid residues and compared with sequences from literature data for other catechol and chlorocatechol dioxygenases.

[Long-term results of replacement of the anterior cruciate ligament in comparison with conservative therapy]

Between January 1980 and February 1987 92 patients (group I) with chronic anterior instability of the knee joint underwent anterior cruciate ligament reconstruction using midthird patellar tendon autografts (BTB). 39 patients (group II) with the same injury were treated conservatively. The patients were followed up postoperatively within a mean period of 8.5 years and stability, grade of postoperative arthrosis, subjective view of patients and ability to sport were evaluated. In group I the clinical examination showed in 77% the same stability on both sides, whereas in group II no cases of bilateral stability of same grade were found. Pivot shifting was repaired in 91% of group I and only in 17% of group II patients. The apparative examination of the stability (KT 2000-arthrometer testing) measuring the anterior drawer phenomenon on both knees showed stable joint conditions (anterior tibia displacement < or = 3 mm) in 86% of operatively treated and only in 8% of conservatively treated patients. Postoperative x-rays showed no arthrotic changes in 55% of group I patients. All patients of group II showed signs of progredient arthrosis in their postoperative x-rays. Subjective clinical results were good to excellent in all group I patients. Only 50% in group II had a good to excellent result. 67% of group I and only 25% of group II patients practiced their former sports activities again. In our retrospective review we could observe significant better clinical results of surgically treated old isolated anterior cruciate ligament (ACL) tears with patellar tendon autografts (BTB) compared to those with conservative treatment.

Coeliac plexus block with bupivacaine reduces intestinal dysfunction in neurosurgical ICU patients

Coeliac plexus block, an established method of treatment for pain associated with pancreatitis and cancer, was used in neurosurgical patients with gastrointestinal dysfunction. The study was performed in 16 patients whose gastric reflux volume exceeded 600 ml per day for 3 consecutive days. Patients were allocated to a block group (n = 8) or a control group (n = 8). Coeliac plexus block was accomplished with a modified Moore technique using 50 ml bupivacaine 0.25%. In the block group, gastric reflux volumes for 3 days preceding coeliac plexus block and 3 consecutive days following coeliac plexus block were analysed. In the control group, gastric reflux volumes were observed over a period of 6 days. Mean (SEM) gastric reflux volume decreased significantly following coeliac plexus block from 770 (50) ml to 60 (30) ml (p < 0.01). In the control group, gastric reflux remained unchanged over the corresponding periods (730 (60) ml c.f. 670 (50) ml). The response of gastric reflux volume to coeliac plexus block suggests that the mechanism is related to inhibition of sympathetic activity in patients whose sympathetic drive is increased due to the underlying neurological disease, and possibly due to sedation withdrawal symptoms.