Weight-bearing MRI with a knee flexion angle of 20°: a study on additional MRI investigation modalities to support a more accurate understanding of patellofemoral instability

Background

Diagnosing patellofemoral instability disorders correctly, weight-bearing MRI (WB-MRI) has become an option. Aiming for a best possible accuracy in displaying potentially underlying causes, the named MRI modalities were sporadically even investigated in different knee flexion angles. However, despite confirmed MRI-outcome-differences between WB-MRI and non-WB-MRI, none of the described MRI modalities have so far established themselves. Mainly this is due to an unfeasibility in daily clinical routine in regard to time and economic aspects. Thus, we intended to evaluate an additional but reduced patellofemoral MR-imaging solely in a relevant 20° of knee flexion under WB- and non-WB-MRI conditions.

Methods

Seventy-three subjects with and without patellofemoral instability were investigated under supine as well as under WB-MRI conditions in a 20° of knee flexion angle. Patellofemoral risk indices in the sagittal plane (Insall-Salvati-Index, Caton-Deschamps-Index, Patellotrochlear Index) and the axial plane (Patella tilt of Fulkerson and Sasaki) were detected and compared between the different MRI conditions. Significance, reliability and Cohen’s effect size was calculated.

Results

Nearly all assessed indices showed significant differences between patients and controls in the different MRI positions. Comparing pairwise, all measured indices failed to show significant differences between the two MRI positions. However, patella tilt angles of the patient group showed an elevation from supine to WB-MRI (14.00 ± 7.54° to 15.97 ± 9.10° and 16.34 ± 7.84° to 18.54 ± 9.43°). Here, Cohen’s d showed small to medium effects between supine and WB-MRI.

Conclusion

In comparison to standard MRI in supine position, axial risk indices seem to be accentuated under WB-MRI and a knee flexion angle of 20°. In particular, symptomatic cases with inconspicuous conventional MRI imaging, additional MRI imaging only in the axial plane in a 20° of knee flexion could be beneficious and useful in clinical daily routine.

Serial clinical and MRI examinations after arthroscopic rotator cuff reconstruction using double-row technique

PURPOSE

Rotator cuff reconstruction using arthroscopic double-row technique enables a better repair of the anatomical footprint at the tendon insertion. Objective of this serial study was to illustrate structural and functional results during recovery following double-row reconstruction.

METHODS

Forty-five patients with mid-sized ruptures of the supraspinatus tendon were assessed prospectively and underwent arthroscopic surgery using the double-row technique. Rupture localization, size, form, and extent of retraction were recorded intraoperatively. Clinical and MRI follow-up examinations were carried out for all patients after 6, 12, 26, and 52 weeks. A A standard protocol was used during the follow-up examinations to determine tendon integration, signal changes in the tendon, extent of bone marrow edema near the enclosed absorbable suture anchors, muscle changes. The clinical results were correlated with the MRI appearance.

RESULTS

After 26 weeks, the Constant score (CS) showed a highly significant increase for the first time with a value of 78 (p < 0.001). Tendon integration according to Sugaya showed a left shift over time, with higher CS-values for lower Sugaya classifications. Significant improvements in strength were first measured between the 26-week and 52-week follow-ups (9->19/p < 0.001). Highly significant improvement (p < 0.001) of the tendon signal and the fatty infiltration was found in the same time interval. The hypotrophy showed slight improvement, while a highly significant reduction of the bone marrow edema was found between weeks 12 and 26 (p < 0.001). There were no re-ruptures after week 26.

CONCLUSIONS

The present serial study showed that it took 26 weeks to reach a significant clinical improvement concerning CS. With regard to tendon healing, no further deterioration of the structural results occurred between week 26 and week 52 postoperative. There were slightly but not significant better clinical results according to the the Sugaya classification. However, parameter "strength" was significantly increased between weeks 26 and 52. This was consistent with a significant decrease in the signal intensity at the repaired tendon site, an additional improvement in the fatty infiltration, and the atrophy according to Thomazeau in the same time interval.

LEVEL OF EVIDENCE

I.

[Bone marrow edema and atraumatic necrosis of the femoral head : Therapy]

BACKGROUND

An increase in interstitial bony fluid occurs in bone-marrow edema (BME). The exact pathogenetic processes still remain unknown. BME is an unspecific finding that can occur on its own or accompany multiple diseases and pathologies.

GOAL

Literature review and presentation of new guidelines.

MATERIAL AND METHODS

This is a narrative literature review followed by current advice for the therapy of atraumatic osteonecrosis of the hip, based on the recently published S3-guidelines for this disease.

RESULTS AND DISCUSSION

The differentiation of at least 3 different etiologies is proposed (mechanic, reactive and ischemic). Difficult, but important, is the distinction between the mostly painful, but benign entities (BME syndrome, bone bruise) and the progressive pathologies (osteonecrosis, arthritis, CRPS, tumour). Treatment options are dependent on etiology and clinic and can often be symptomatic. Core decompression is the surgical gold standard, leading to immediate pressure relief and therefore reduction in pain. Recently, it was shown that intravenous administration of Iloprost and bisphosphonates are also effective in achieving a reduction of BME and pain, with considerable improvement in the accompanying symptoms. The combination of core decompression and infusion seems to be another possible optimization ofthe therapy, in particular in the treatment of osteonecrosis.

Radiographic monitoring of the distal insertion of the calcaneofibular ligament in anatomical reconstructions of ankle instabilities: A preliminary cadaveric study

BACKGROUND

The purpose of the study therefore was to determine radiographic landmarks that support the identification of the insertion site of the distal calcaneofibular ligament (CFL) in anatomic ankle ligament reconstructions.

METHODS

In 10 lower limb cadaver specimens the midpoint of the distal CFL insertion was dissected and marked with a nail inserted orthogonally. On a standardized lateral radiograph in neutral ankle position a horizontal tangent was aligned to the deepest visible concavity of the tarsal sinus and one vertical tangent to the farthest posterior convexity of the talus. Additionally, a line was drawn from the radiographically marked distal CFL to the fibular insertion of the CFL to determine the CFL-fibular angle.

RESULTS

In relation to the radiographic tangents intersection the mean deviation of the depicted CFL nails was 2.2mm [SD ± 1.1 mm] leading to an angular, circular to slightly oval 6 mm insertion. The scatter-plot of the marked positions convened along a line from the supposed fibular CFL insertion to the intersection in all cases. The mean CFL-fibular angle was 131.7° [SD ± 3.16°].

CONCLUSIONS

Determining a virtual intersection between a horizontal tangent aligned to the deepest visible concavity of the tarsal sinus and one vertical tangent aligned to the farthest posterior convexity of the talus on a standardized lateral radiograph in neutral ankle position supports an anatomic insertion of the distal calcaneofibular ligament most probably.

[Weightings and sequences in magnetic resonance imaging in orthopedic surgery]

Magnetic resonance imaging (MRI) plays a very important role in the diagnosis of musculoskeletal conditions; its importance in orthopedic trauma continues to grow. To ensure optimal imaging and to be able to answer all clinically relevant questions, some prerequisites must be taken into account. Of uttermost importance is a functioning communication between surgeons and radiologists. To adapt the best sequences, the radiologist needs to know all suspected injuries and the mechanism of trauma. Second, the surgeon must have basic knowledge regarding this technology to optimally use all its possibilities. The aim of this article is to familiarize the reader with basic MRI in traumatology focusing on weightings and sequences.

[The utilization of MRI by orthopaedic surgeons: requirements and limitations]

BACKGROUND

The tendency in surgical fields to subspecialize continues. Diagnostic possibilities and surgical indications are becoming more and more sophisticated. As a consequence, surgeons in Germany have the possibility to acquire qualifications in magnetic resonance imaging (MRI) and are allowed to employ MRI scanners without consulting radiologists.

AIMS

This article aims to describe the requirements to achieve this special qualification and to give a summary on the legal issues in this matter.

[MRI in musculoskeletal imaging: possibilities and limitations]

Muscle injuries are the most frequent sport injuries in athletes. In addition to a thorough clinical examination and the history of the trauma mechanism, imaging modalities are required to correctly classify the injury and plan the future treatment and rehabilitation. The two major modalities are ultrasound and magnet resonance imaging (MRI). This article aims to give a comprehensive overview on the possibilities and limitations of MRI imaging in musculoskeletal injuries as well as insight into current development, classifications and technologies.

[Personal genomics: are we debating the right Issues?]

The debate about personal genomics and their role in personalized medicine has been, to some extent, hijacked by the controversy about commercially available genomic tests sold directly to consumers. The clinical validity and utility of such tests are currently limited and most medical associations recommend that consumers refrain from testing. Conversely, DTC genomics proponents and particularly the DTC industry argue that there is personal utility in acquiring genomic information. While it is necessary to debate risks and benefits of DTC genomics, we should not lose sight of the increasingly important role that genomics will play in medical practice and public health. Therefore, and in anticipation of this shift we also need to focus on important implications from the use of genomics information such as genetic discrimination, privacy protection and equitable access to health care. Undoubtedly, personal genomics will challenge our social norms maybe more than our medicine. Sticking to the polarization of «to have or not to have DTC genomics» risks to takes us away from the critical issues we need to be debating.

Immunocytochemical determination of the subcellular distribution of ascorbate in plants

Ascorbate is an important antioxidant in plants and fulfills many functions related to plant defense, redox signaling and modulation of gene expression. We have analyzed the subcellular distribution of reduced and oxidized ascorbate in leaf cells of Arabidopsis thaliana and Nicotiana tabacum by high-resolution immuno electron microscopy. The accuracy and specificity of the applied method is supported by several observations. First, preadsorption of the ascorbate antisera with ascorbic acid or dehydroascorbic acid resulted in the reduction of the labeling to background levels. Second, the overall labeling density was reduced between 50 and 61% in the ascorbate-deficient Arabidopsis mutants vtc1-2 and vtc2-1, which correlated well with biochemical measurements. The highest ascorbate-specific labeling was detected in nuclei and the cytosol whereas the lowest levels were found in vacuoles. Intermediate labeling was observed in chloroplasts, mitochondria and peroxisomes. This method was used to determine the subcellular ascorbate distribution in leaf cells of plants exposed to high light intensity, a stress factor that is well known to cause an increase in cellular ascorbate concentration. High light intensities resulted in a strong increase in overall labeling density. Interestingly, the strongest compartment-specific increase was found in vacuoles (fourfold) and in plastids (twofold). Ascorbate-specific labeling was restricted to the matrix of mitochondria and to the stroma of chloroplasts in control plants but was also detected in the lumen of thylakoids after high light exposure. In summary, this study reveals an improved insight into the subcellular distribution of ascorbate in plants and the method can now be applied to determine compartment-specific changes in ascorbate in response to various stress situations.

[First traumatic anterior shoulder dislocation: postoperative results 6 months and 2 years after arthroscopic stabilization in young patients]

BACKGROUND

The purpose of this prospective clinical trial was to report about results of primary or early secondary arthroscopic stabilization after first traumatic anterior dislocation of the shoulder.

PATIENTS AND METHODS

Within 2 weeks or in the 7th to 12th week post trauma, 51 subjects between 16 and 30 years received arthroscopic stabilization and rehabilitation. The patients were followed-up 6 months and 2 years post operation and assessed with the Rowe and the Constant scores.

RESULTS

At a mean follow-up of 27.9+/-4.3 months all patients returned to work in their profession. Of the patients, 79.2% were satisfied with the result of the operation; 91.7% returned to their sports. During the follow-up period five patients (10.4%) suffered redislocation. There was no difference in the result comparing the time of operation. The Rowe and Constant scores showed excellent results.

CONCLUSIONS

Arthroscopic stabilization after first traumatic anterior shoulder dislocation of the young patient is an appropriate approach and regardless of whether it is performed as a primary or early secondary operation it significantly lowers the redislocation rate. The method leads to quick reintegration into professional life and sports activities.

Subcellular immunocytochemical analysis detects the highest concentrations of glutathione in mitochondria and not in plastids

The tripeptide glutathione is a major antioxidant and redox buffer with multiple roles in plant metabolism. Glutathione biosynthesis is restricted to the cytosol and the plastids and the product is distributed to the various organelles by unknown mechanisms. In the present study immunogold cytochemistry based on anti-glutathione antisera and transmission electron microscopy was used to determine the relative concentration of glutathione in different organelles of Arabidopsis thaliana leaf and root cells. Glutathione-specific labelling was detected in all cellular compartments except the apoplast and the vacuole. The highest glutathione content was surprisingly not found in plastids, which have been described before as a major site of glutathione accumulation, but in mitochondria which lack the capacity for glutathione biosynthesis. Mitochondria of both leaf and root cells contained 7-fold and 4-fold, respectively, higher glutathione levels than plastids while the density of glutathione labelling in the cytosol, nuclei, and peroxisomes was intermediate. The accuracy of the glutathione labelling is supported by two observations. First, pre-adsorption of the anti-glutathione antisera with glutathione reduced the density of the gold particles in all organelles to background levels. Second, the overall glutathione-labelling density was reduced by about 90% in leaves of the glutathione-deficient Arabidopsis mutant pad2-1 and increased in transgenic plants with enhanced glutathione accumulation. Hence, there was a strong correlation between immunocytochemical and biochemical data of glutathione accumulation. Interestingly, the glutathione labelling of mitochondria in pad2-1 remained very similar to wild-type plants thus suggesting that the high mitochondrial glutathione content is maintained in a situation of permanent glutathione-deficiency at the expense of other glutathione pools. High and constant levels of glutathione in mitochondria appear to be particularly important in cell survival strategies and it is predicted that mitochondria must have highly competitive mitochondrial glutathione uptake systems. The present results underline the suggestion that subcellular glutathione concentrations are not controlled by a global mechanism but are controlled on an individual basis and it is therefore not possible to conclude from global biochemical glutathione analysis on the status of the various organellar pools.

Shoulder Rotation Characteristics in Professional Tennis Players

Aim of this study was to assess the glenohumeral joint internal and external rotational range of motion using an ultrasound based kinematic measurement device. Twenty-seven male professional tennis players were bilaterally measured for internal and external rotation at 90 degrees of shoulder abduction while avoiding scapulothoracic motion. The control group consisted of 20 asymptomatic volunteers not involved in overhead sports activities. The dominant arm (playing arm) had a significantly greater range of external rotation than the non-dominant arm, while their internal rotation showed a significant deficit as compared to the non-dominant arm. The dominant arm total rotational range of motion was also significantly reduced in comparison to the non-dominant arm and to the controls. No significant difference was found between the dominant and non-dominant extremity in the control group. For objective measurement of glenohumeral rotational range of motion ultrasound based real time motion analysis is a new application for the diagnostic testing of specific shoulder parameters in orthopedics and sports physical therapy. It is therefore concluded that the specific methodology aiming at isolated glenohumeral motion may have clinical application for the development of rehabilitation and preventative programs.

Characterization of an Arabidopsis-Phytophthora pathosystem: resistance requires a functional PAD2 gene and is independent of salicylic acid, ethylene and jasmonic acid signalling

Arabidopsis accessions were screened with isolates of Phytophthora porri originally isolated from other crucifer species. The described Arabidopsis-Phytophthora pathosystem shows the characteristics of a facultative biotrophic interaction similar to that seen in agronomically important diseases caused by Phytophthora species. In susceptible accessions, extensive colonization of the host tissue occurred and sexual and asexual spores were formed. In incompatible combinations, the plants reacted with a hypersensitive response (HR) and the formation of papillae at the sites of attempted penetration. Defence pathway mutants such as jar1 (jasmonic acid-insensitive), etr1 (ethylene receptor mutant) and ein2 (ethylene-insensitive) remained resistant towards P. porri. However, pad2, a mutant with reduced production of the phytoalexin camalexin, was hyper-susceptible. The accumulation of salicylic acid (SA) and PR1 protein was strongly reduced in pad2. Surprisingly, this lack of SA accumulation does not appear to be the cause of the hyper-susceptibility because interference with SA signalling in nahG plants or sid2 or npr1 mutants had only a minor effect on resistance. In addition, the functional SA analogue benzothiadiazol (BTH) did not induce resistance in susceptible plants including pad2. Similarly, the complete blockage of camalexin biosynthesis in pad3 did not cause susceptibility. Resistance of Arabidopsis against P. porri appears to depend on unknown defence mechanisms that are under the control of PAD2.

Manipulation of salicylate content in Arabidopsis thaliana by the expression of an engineered bacterial salicylate synthase

Salicylic acid (SA) plays a central role as a signalling molecule involved in plant defense against microbial attack. Genetic manipulation of SA biosynthesis may therefore help to generate plants that are more disease-resistant. By fusing the two bacterial genes pchA and pchB from Pseudomonas aeruginosa, which encode isochorismate synthase and isochorismate pyruvate-lyase, respectively, we have engineered a novel hybrid enzyme with salicylate synthase (SAS) activity. The pchB-A fusion was expressed in Arabidopsis thaliana under the control of the constitutive cauliflower mosaic virus (CaMV) 35S promoter, with targeting of the gene product either to the cytosol (c-SAS plants) or to the chloroplast (p-SAS plants). In p-SAS plants, the amount of free and conjugated SA was increased more than 20-fold above wild type (WT) level, indicating that SAS is functional in Arabidopsis. P-SAS plants showed a strongly dwarfed phenotype and produced very few seeds. Dwarfism could be caused by the high SA levels per se or, perhaps more likely, by a depletion of the chorismate or isochorismate pools of the chloroplast. Targeting of SAS to the cytosol caused a slight increase in free SA and a significant threefold increase in conjugated SA, probably reflecting limited chorismate availability in this compartment. Although this modest increase in total SA content did not strongly induce the resistance marker PR-1, it resulted nevertheless in enhanced disease resistance towards a virulent isolate of Peronospora parasitica. Increased resistance of c-SAS lines was paralleled with reduced seed production. Taken together, these results illustrate that SAS is a potent tool for the manipulation of SA levels in plants.

Construction and application of a microprojectile system for the transfection of organotypic brain slices

In this study we outline a method for constructing an inexpensive chamber used in the transfection of organotypic brain slices. This chamber differs from most commercially available chambers in that DNA-coated gold microcarriers are directly carried by a flow of helium at low pressure (26 psi). Most other chambers employ macrocarriers onto which DNA-coated gold is first loaded, and then released by a shock of helium onto the reverse side of the macrocarriers. This home constructed device has been successfully employed in the transfection of organotypic brain slices cultured using the air-medium interface method. Mammalian expression vectors containing cytomegalovirus (CMV) and simian virus (SV40) enhancers/promoters were used to express enhanced green fluorescence protein (EGFP). DNA was coated onto 0.6-microm gold microcarriers. Transfected cells were visualised under a fluorescence microscope and included identifiable neurones and oligodendrocytes. Also included in this study are step-by-step methods for the preparation of gold microcarriers and organotypic brain slices.

Constitutive expression of the defense-related Rir1b gene in transgenic rice plants confers enhanced resistance to the rice blast fungus Magnaporthe grisea

The Rirlb gene of rice (Oryza sativa) is one of a set of putative defense genes whose transcripts accumulate upon inoculation of rice with the non-host pathogen Pseudomonas syringae pv. syringae. It belongs to a family of genes encoding small extracellular proteins so far only identified in cereals. To assess the function of the Rirlb gene in rice blast resistance, it was placed under the control of the CaMV 35S promoter and transferred into rice plants of the japonica variety Taipei 309 by biolistic transformation of immature embryos. Two out of 12 hygromycin-resistant regenerated plants (OE1 and OE3) were fertile. DNA gel blot analysis suggested that these two T0 plants were independent transformants, each of which had stably incorporated one complete copy of the transgene into the genome. In addition, the OE1 plant appeared also a contain a rearranged copy or incomplete copy. T1 plants homozygous for the transgene were identified by DNA gel blot analysis of individual T2 progeny and further propagated. Expression analysis of the transgene showed that the transgene was active both in T1 plants and homozygous decendants. Challenge inoculation of homozygous transgenic plants with Magnaporthe grisea, the causal agent of rice blast disease, revealed that both independent transgenic lines were more resistant than the untransformed wild type, suggesting that over-expression of the Rirlb gene confers partial resistance against this important pathogen.

[Traumatic dislocation of long fingers at the metacarpophalangeal joint while bowling--case report of an extremely rare injury]

The case of a 55-year old male patient, who got a luxation of the four long fingers while bowling, is presented. After reposition, fixing in "Intrinsic-plus"-position for two weeks and accompanied physiotherapy, a good functional result of the right hand was obtained. Mechanism of accident, diagnosis, therapy and complications are discussed.

Characterization of the rice pathogen-related protein Rir1a and regulation of the corresponding gene

In rice (Oryza sativa L.), local acquired resistance against Pyricularia oryzae (Cav.), the causal agent of rice blast, can be induced by a preinoculation with the non-host pathogen Pseudomonas syringae pv. syringae. We have cloned a cDNA (Rir1a) and a closely related gene (Rir1b) corresponding to transcripts that accumulate in leaf tissue upon inoculation with P. syringae pv. syringae. The cDNA encodes a putative 107 amino acid protein, Rir1a, that exhibits a putative signal peptide cleavage site in its hydrophobic N-terminal part and a C-terminal part that is relatively rich in glycine and proline. The Rir1b gene contains a Tourist and a Wanderer miniature transposable element in its single intron and encodes a nearly identical protein. Rir1a is similar in sequence (ca. 35% identical and ca. 60% conservatively changed amino acids) to the putative Wir1 family of proteins that are encoded by pathogen-induced transcripts in wheat. Using antibodies raised against a Rir1a-fusion protein we show that Rir1a is secreted from rice protoplasts transiently expressing a 35S::Rir1a construct and that the protein accumulates in the cell wall compartment of rice leaves upon inoculation with P. syringae pv. syringae. Possible roles of Rir1a in pathogen defense are discussed.

Properties and function of the P type ion pumps cloned from Helicobacter pylori

Three distinct P type pumps were cloned from H. pylori 69A. Two of these pumps, ATPase 439 and ATPase 948 (CopA), were isolated by gene library screening using DNA oligonucleotide primers. Amino acid similarities found for the predicted proteins were about 50% to Cd2+/Cu2+ pumps. Gene disruption mutagenesis rendered the H. pylori knockout mutants more sensitive to Zn2+ and Cd2+ (ATPase 439) or Cu2+ (CopA). Some of the ATPase 439-deficient mutants were negative for urease activity while the majority of the mutants remained positive. Functional diversity of the pumps was also reflected by the ion affinities found for N-terminal peptides of CopA to Cu2+ and of ATPase 439 to Ni2+, Cu2+ and CO2+. The membrane domain of the two pumps were experimentally shown to consist of eight membrane spans. When ATPase 439 was expressed under control of a tac promoter in Escherichia coli, vanadate-sensitive phosphate accumulation was observed cytochemically along the membrane of the host cells. The third P type pump (ATPase 115) which also exhibited homology to transition metal ATPase was identified by sequencing a library of H. pylori membrane genes. The hydropathy plot of this pump was very similar to the former H. pylori ATPases whereas the N-terminal ion binding region was distinct. It was concluded that, in H. pylori, the presence of three transition metal ATPases with distinct ion specificity contributes to the adaptive mechanisms for gastric survival.

Mechanosensitive expression of a lipoxygenase gene in wheat

Touch stimulation of wheat (Triticum aestivum L.) seedlings led to a strong and dose-dependent increase in the level of lipoxygenase mRNA transcripts. The touch-induced response occurred within 1 h and was transient. A similar response was observed after wind treatment and wounding. The mechanical strain-regulated lipoxygenase might translate mechanical strain into lipoxygenase pathway-dependent growth responses.

Identification of structures containing polyphosphate in Helicobacter pylori

For the first time polyphosphate (poly P) granules have been detected in Helicobacter pylori organisms colonizing the gastric antrum as well as in organisms isolated from the same tissue. Poly P granules showed typical sublimation characteristics during exposure to the electron beam and chipped out of ultrathin sectioning. A prominent phosphorus signal was identified using elemental specific electron microscopy such as electron energy loss spectroscopy (EELS) and was localized to at least three different locations: the cytoplasm, the flagellar pole and in association with the cell membrane. Intracytoplasmatic structures had a diameter of 0.05-0.2 micron, whereas the structures near the flagellar pole were much smaller (0.02 micron). The membrane-associated phosphate aggregates were visible only after staining with Pb(NO3)2 or with electron spectroscopic imaging (ESI). Poly P granules seem to be important energy and phosphorus stores and it is thought that they participate in the regulation of various and distinct metabolic processes of H. pylori.

The coccoid forms of Helicobacter pylori. Criteria for their viability

The fact that Helicobacter pylori can revert to a coccoid form has stimulated speculation about its role in transmission and as a possible cause of reinfection in duodenal ulcer disease. Bismuth subcitrate (32 micrograms/ml), bismuth subsalicylate (64 micrograms/ml), amoxicillin (0.05 micrograms/ml) and erythromycin (4 micrograms/ml) inhibited the growth of H. pylori and stimulated the formation of basically respiring but non-culturable coccoid structures. The presence of polyphosphates as energy and phosphorus source permits a certain level of endogenous metabolism to preserve RNA and DNA, as well as structural components like cell wall, cell membrane and cytoplasma for at least 3 months. However, the applied standard laboratory methods were insufficient for regrowth of H. pylori out of the coccoid form.

Demonstration of a phospholipid-rich zone in the human gastric epithelium damaged by Helicobacter pylori

BACKGROUND

Recently, a hydrophobic layer has been shown by the contact angle method in human gastric biopsy specimens. The aim of this study was to show the existence of a phospholipid-rich layer in the human gastric epithelium and to investigate the influence of Helicobacter pylori on these structures.

METHODS

Biopsy specimens from the gastric antrum were obtained during gastroscopy from patients with normal gastric mucosa as well as from patients with H. pylori-positive gastritis for electron microscopical and histological examination. Structures reacting with a phospholipid-selective stain, iodoplatinate were analyzed by electron microscopy and electron-dispersive x-ray microanalysis.

RESULTS

Both methods revealed the morphological existence of a phospholipid-rich zone covering the human gastric epithelial layer. Reaction products could be localized within the cells, at the epithelium closely associated with the surface, and in connection with the mucus. In infected tissue, H. pylori affects iodoplatinate-reactive material within the mucous layer and material covering the epithelium.

CONCLUSIONS

The phospholipid-rich zone in the apical region of surface mucous cells is likely to represent an important factor of the gastric protective system in humans. The destruction of this hydrophobic layer may result in a reduction of hydrophobicity giving access to gastric acid.

Differential induction of distinct glutathione-S-transferases of wheat by xenobiotics and by pathogen attack

We have previously characterized a pathogen-induced gene from wheat (Triticum aestivum L.) that was named GstA1 based on sequence similarities with glutathione-S-transferases (GSTs) of maize (R. Dudler, C. Hertig, G. Rebmann, J. Bull, F. Mauch [1991] Mol Plant Microbe Interact 4: 14-18). We have constructed a full-length GstA1 cDNA by combinatorial polymerase chain reaction and demonstrate by functional expression of the cDNA in Escherichia coli that the GstA1-encoded protein has GST activity. An antiserum raised against a GstA1 fusion protein specifically recognized a protein with an apparent molecular mass of 29 kD on immunoblots of extracts from bacteria expressing the GstA1 cDNA and extracts from wheat inoculated with Erysiphe graminis. The GstA1-encoded protein was named GST29. RNA and immunoblot analysis showed that GstA1 was only weakly expressed in control plants and was specifically induced by pathogen attack and by the GST substrate glutathione, but not by various xenobiotics. In contrast, a structurally and antigenically unrelated GST with an apparent molecular mass of 25 kD that was detected with an antiserum raised against GSTs of maize was expressed at a high basal level. This GST25 and an additional immunoreactive protein named GST26 were strongly induced by cadmium and by the herbicides atrazine, paraquat, and alachlor, but not by pathogen attack. Compared with the pathogen-induced GST29, GST25 and GST26 showed a high affinity toward glutathione-agarose and were much more active toward the model substrate 1-chloro-2,4-dinitrobenzene. Thus, wheat contains at least two distinct GST classes that are differentially regulated by xenobiotics and by pathogen attack and whose members have different enzymic properties. GST25 and GST26 appear to have a function in xenobiotic metabolism, whereas GST29 is speculated to fulfill a more specific role in defense reactions against pathogens.

[Polymorphism in Helicobacter pylori--a key function in recurrence of infection?]

Despite the fact that Helicobacter (H.) pylori is ubiquitous throughout the world, little is known at present about the source of infection and mode of transmission. Person-to-person transmission may be of importance. The fact that Helicobacter pylori can revert to a coccoid form stimulated speculation about its role in transmission and as a possible cause of reinfection in duodenal ulcer disease. Various antibacterial agents (bismuth subcitrate 32 mg/l bismuth subsalicylate 64 mg/l, amoxicillin 0.05 mg/l, ampicillin 2 mg/l, erythromycin 4 mg/l, glycochenodeoxycholic acid 423 mg/l, ursodeoxycholic acid 540 mg/l) inhibit the growth of H. pylori and stimulate the formation of coccoid structures. Ultrastructural and biochemical results show that the coccoid form meets the necessary criteria for survival. Thus, to be successful, treatment must aim not only at eliminating the vegetative form, but also at preventing the development of the coccoid form.

Ethylene-induced chitinase and β-1,3-glucanase accumulate specifically in the lower epidermis and along vascular strands of bean leaves

We have studied the spatial pattern of accumulation of chitinase (EC 3.2.1.14) and β-1,3-glucanase (EC 3.2.1.39) in ethylene-treated leaves of bean (Phaseolus vulgaris L.). Electron-microscopical examination of chemically fixed tissue demonstrated the presence of large electron-dense aggregates in the vacuoles of ethylene-treated leaf cells. No such vacuolar structures were observed in untreated control cells. Immunogold labelling with antisera directed against the basic forms of chitinase and β-1,3-glucanase indicated that the vacuolar aggregates were the major site of accumulation of chitinase and β-1,3-glucanase. The chitinase- and β-1,3-glucanase-containing vacuolar aggregates were not randomly distributed within the leaf tissue but were restricted to the lower epidermal cells and to parenchyma cells adjacent to vascular strands. In addition, heavy β-1,3-glucanase labelling was observed over spongy plugs of expanded middle-lamella material that appear to occlude the transition regions between the airspaces underlying the stomata and those throughout the rest of the leaf. Some labelling was also seen to extend along the surface layer of the cell walls lining all of the airspaces. Protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting as well as enzyme-activity measurements showed that the peeled lower epidermis of the ethylene-treated leaves contained on a protein and on a per-weight basis several times more chitinase and β-1,3-glucanase than the remainder of the leaf.

A pathogen-induced wheat gene encodes a protein homologous to glutathione-S-transferases

Winter wheat (Triticum aestivum) shows local, induced resistance against the plant-pathogenic fungus Erysiphe graminis f. sp. tritici following exposure to the nonpathogen E. g. f. sp. hordei. The onset of this resistance has been shown to be correlated with the activation of putative defense genes, and cDNA clones representing transcripts of induced genes have been obtained (P. Schweizer, W. Hunziker, and E. Mösinger, Plant Molecular Biology 12:643-654, 1989). We have cloned and sequenced a gene corresponding to one of these cDNAs, WIR5. Sequence analysis indicated that this gene contains three exons and encodes a protein of 229 amino acids. S1 mapping showed that transcripts homologous to this gene are at least 20 times more abundant in leaves infected 14 hr earlier with E. g. f. sp. hordei than in control leaves. Sequence comparison showed that the WIR5 gene product is highly homologous to glutathione-S-transferases (GSTs; EC 25.1.18) of maize. This, together with the fact that the intron positions of both the wheat gene and the maize GSTI gene are conserved, suggests that the cloned pathogen-induced gene, named GstA1, encodes a wheat glutathione-S-transferase.

Functional Implications of the Subcellular Localization of Ethylene-Induced Chitinase and [beta]-1,3-Glucanase in Bean Leaves

Plants respond to an attack by potentially pathogenic organisms and to the plant stress hormone ethylene with an increased synthesis of hydrolases such as chitinase and [beta]-1,3-glucanase. We have studied the subcellular localization of these two enzymes in ethylene-treated bean leaves by immunogold cytochemistry and by biochemical fractionation techniques. Our micrographs indicate that chitinase and [beta]-1,3-glucanase accumulate in the vacuole of ethylene-treated leaf cells. Within the vacuole label was found predominantly over ethylene-induced electron dense protein aggregates. A second, minor site of accumulation of [beta]-1,3-glucanase was the cell wall, where label was present nearly exclusively over the middle lamella surrounding intercellular air spaces. Both kinds of antibodies labeled Golgi cisternae of ethylene-treated tissue, suggesting that the newly synthesized chitinase and [beta]-1,3-glucanase are processed in the Golgi apparatus. Biochemical fractionation studies confirmed the accumulation in high concentrations of both chitinase and [beta]-1,3-glucanase in isolated vacuoles, and demonstrated that only [beta]-1,3-glucanase, but not chitinase, was present in intercellular washing fluids collected from ethylene-treated leaves. Based on these results and earlier studies, we propose a model in which the vacuole-localized chitinase and [beta]-1,3-glucanase are used as a last line of defense to be released when the attacked host cells lyse. The cell wall-localized [beta]-1,3-glucanase, on the other hand, would be involved in recognition processes, releasing defense activating signaling molecules from the walls of invading pathogens.

Antifungal Hydrolases in Pea Tissue : II. Inhibition of Fungal Growth by Combinations of Chitinase and beta-1,3-Glucanase

Chitinase and beta-1,3-glucanase purified from pea pods acted synergistically in the degradation of fungal cell walls. The antifungal potential of the two enzymes was studied directly by adding protein preparations to paper discs placed on agar plates containing germinated fungal spores. Protein extracts from pea pods infected with Fusarium solani f.sp. phaseoli, which contained high activities of chitinase and beta-1,3-glucanase, inhibited growth of 15 out of 18 fungi tested. Protein extracts from uninfected pea pods, which contained low activities of chitinase and beta-1,3-glucanase, did not inhibit fungal growth. Purified chitinase and beta-1,3-glucanase, tested individually, did not inhibit growth of most of the test fungi. Only Trichoderma viride was inhibited by chitinase alone, and only Fusarium solani f.sp. pisi was inhibited by beta-1,3-glucanase alone. However, combinations of purified chitinase and beta-1,3-glucanase inhibited all fungi tested as effectively as crude protein extracts containing the same enzyme activities. The pea pathogen, Fusarium solani f.sp. pisi, and the nonpathogen of peas, Fusarium solani f.sp. phaseoli, were similarly strongly inhibited by chitinase and beta-1,3-glucanase, indicating that the differential pathogenicity of the two fungi is not due to differential sensitivity to the pea enzymes. Inhibition of fungal growth was caused by the lysis of the hyphal tips.

Antifungal Hydrolases in Pea Tissue : I. Purification and Characterization of Two Chitinases and Two beta-1,3-Glucanases Differentially Regulated during Development and in Response to Fungal Infection

Chitinase and beta-1,-3-glucanase activities increased coordinately in pea (Pisum sativum L. cv "Dot") pods during development and maturation and when immature pea pods were inoculated with compatible or incompatible strains of Fusarium solani or wounded or treated with chitosan or ethylene. Up to five major soluble, basic proteins accumulated in stressed immature pods and in maturing untreated pods. After separation of these proteins by chromatofocusing, an enzymic function could be assigned to four of them: two were chitinases and two were beta-1,3-glucanases. The different molecular forms of chitinase and beta-1,3-glucanase were differentially regulated. Chitinase Ch1 (mol wt 33,100) and beta-1,3-glucanase G2 (mol wt 34,300) were strongly induced in immature tissue in response to the various stresses, while chitinase Ch2 (mol wt 36,200) and beta-1,3-glucanase G1 (mol wt 33,500) accumulated during the course of maturation. With a simple, three-step procedure, both chitinases and both beta-1,3-glucanases were purified to homogeneity from the same extract. The two chitinases were endochitinases. They differed in their pH optimum, in specific activity, in the pattern of products formed from [(3)H]chitin, as well as in their relative lysozyme activity. Similarly, the two beta-1,3-glucanases were endoglucanases that showed differences in their pH optimum, specific activity, and pattern of products released from laminarin.

Ethylene: Symptom, Not Signal for the Induction of Chitinase and beta-1,3-Glucanase in Pea Pods by Pathogens and Elicitors

Infection of immature pea pods with Fusarium solani f.sp. phaseoli (a non-pathogen of peas) or f.sp. pisi (a pea pathogen) resulted in induction of chitinase and beta-1,3-glucanase. Within 30 hours, activities of the two enzymes increased 9-fold and 4-fold, respectively. Chitinase and beta-1,3-glucanase were also induced by autoclaved spores of the two F. solani strains and by the known elicitors of phytoalexins in pea pods, cadmium ions, actinomycin D, and chitosan. Furthermore, exogenously applied ethylene caused an increase of chitinase and beta-1,3-glucanase in uninfected pods. Fungal infection or treatment with elicitors strongly increased ethylene production by immature pea pods. Infected or elicitor-treated pea pods were incubated with aminoethoxyvinylglycine, a specific inhibitor of ethylene biosynthesis. This lowered stress ethylene production to or below the level of uninfected controls; however, chitinase and beta-1,3-glucanase were still strongly induced. It is concluded that ethylene and fungal infection or elicitors are separate, independent signals for the induction of chitinase and beta-1,3-glucanase.

Chitinase in bean leaves: induction by ethylene, purification, properties, and possible function

Ethylene induced an endochitinase in primary leaves of Phaseolus vulgaris L. The enzyme formed chitobiose and higher chitin oligosaccharides from insoluble, colloidal or regenerated chitin. Less than 5% of the total chitinolytic activity was detected in an exochitinase assay proposed by Abeles et al. (1970, Plant Physiol. 47, 129-134) for ethylene-induced chitinase. In ethylene-treated plants, chitinase activity started to increase after a lag of 6 h and was induced 30 fold within 24 h. Exogenously supplied ethylene at 1 nl ml(-1) was sufficient for half-maximal induction, and enhancement of the endogenous ethylene formation also enhanced chitinase activity. Cycloheximide prevented the induction. Among various hydrolases tested, only chitinase and, to a lesser extent, β-1,3-glucanase were induced by ethylene. Induction of chitinase by ethylene occurred in many different plant species. Ethylene-induced chitinase was purified by affinity chromatography on a column of regenerated chitin. Its apparent molecular weight obtained by sodium dodecyl sulfate-gel electrophoresis was 30,000; the molecular weight determined from filtration through Sephadex G-75 was 22,000. The purified enzyme attacked chitin in isolated cell walls of Fusarium solani. It also acted as a lysozyme when incubated with Micrococcus lysodeikticus. It is concluded that ethylene-induced chitinase functions as a defense enzyme against fungal and bacterial invaders.