Hoffa fractures are associated with concomitant soft tissue injures and a high postoperative complication rate.

INTRODUCTION: Hoffa fractures are a rare and often overlooked entity. The main goal of surgical treatment is to restore the articular surface and maintain knee function. However, current clinical data indicate heterogeneous outcomes. The aim of this multicenter study was to obtain a representative data set of patients with isolated Hoffa fractures with special emphasis on concomitant soft tissue injuries, diagnostic algorithms, treatment strategies and functional outcomes. MATERIALS AND METHODS: Participating Level I trauma centres were asked to review their internal database for isolated Hoffa fractures treated surgically between 2010 and 2020. Demographics, mechanism of injury, diagnostic and therapeutic algorithm, Letenneur classification, concomitant soft tissue injuries, and postoperative knee function and complications were analysed. RESULTS: A total of 56 patients from six participating trauma centres were included. The median age at injury was 45 years (15-94) with a median follow-up of 19 months (2-108). The most common mechanism of injury was high-energy trauma, with unicondylar lateral Letenneur type I and II fractures being the most common. Surgical treatment was independent of the type of fracture and included isolated screw fixation, combined plate and screw fixation and isolated plate osteosynthesis. Isolated screw fixation resulted in significantly better range of motion (ROM) values (p = 0.032), but the highest number of postoperative complications (n = 14/20, n.s.) compared to the other fixation techniques. The highest number of fixation failures requiring revision was observed in the plate and screw fixation group (n = 3/8, p = 0.008). Osteochondral flake fractures (n = 12/43, 27%) and lateral meniscus injuries (n = 5/49, 10%) were commonly seen in Hoffa fractures. CONCLUSIONS: Treatment of Hoffa fractures with screw fixation resulted in significantly better functional outcomes, probably due to less comminuted fractures. Concomitant cartilage, meniscal and ligamentous injuries are common and warrant preoperative recognition and management.

Primary stability of single-stage revision reconstruction of the anterior cruciate ligament in case of failure of dynamic intraligamentary stabilization depends on implant position during ACL repair.

INTRODUCTION: The object of this study was to evaluate the primary stability of tibial interference screw (IFS) fixation in single-stage revision surgery of the anterior cruciate ligament (ACL) in the case of recurrent instability after ACL repair with dynamic intraligamentary stabilization (DIS), dependent on the implant position during DIS. MATERIALS AND METHODS: Tibial aperture fixation in ACL reconstruction (ACL-R) was performed in a porcine knee model using an IFS. Native ACL-R was performed in the control group (n = 15). In the intervention groups DIS and subsequent implant removal were performed prior to single-stage revision ACL-R. A distance of 20 mm in group R-DIS1 (n = 15) and 5 mm in group R-DIS2 (n = 15) was left between the joint line and the implant during DIS. Specimens were mounted in a material-testing machine and load-to-failure was applied in a worst-case-scenario. RESULTS: Load to failure was 454 ± 111 N in the R-DIS1 group, 154 ± 71 N in the R-DIS2 group and 405 ± 105 N in the primary ACL-R group. Load-to-failure, stiffness and elongation of the group R-DIS2 were significantly inferior in comparison to R-DIS1 and ACL-R respectively (p < 0.001). No significant difference was found between load-to-failure, stiffness and elongation of R-DIS1 and the control group. CONCLUSION: Primary stability of tibial aperture fixation in single-stage revision ACL-R in case of recurrent instability after DIS depends on monobloc position during ACL repair. Primary stability is comparable to aperture fixation in primary ACL-R, if a bone stock of 20 mm is left between the monobloc and the tibial joint line during the initial procedure.

FRET-based cyanine probes for monitoring ligation reactions and their applications to mechanistic studies and catalyst screening.

There is an ever-increasing need to design better methods to selectively connect two molecules under mild aqueous conditions on a small scale. The process of finding such methods significantly relies on the employment of an appropriate assay. We report here a modular FRET-based assay to monitor such reactions and illustrate how the assay is used to monitor two particular reactions: native chemical ligation (NCL) and oxime ligation. For both reactions we show that by employing appropriately designed probes FRET measurements could be used to monitor the reaction's progress. We additionally demonstrate the usefulness of the developed probe system to study the mechanisms of the ligation reactions, for example, in monitoring the formation of a trimeric intermediate in the NCL reaction. Finally, we demonstrate that FRET measurements conducted in our system allow the quantification of the reaction yield and we show the application of our FRET-based assay to catalyst screening for the oxime ligation.

Functional assessments for decision-making regarding return to sports following ACL reconstruction. Part II: clinical application of a new test battery.

PURPOSE: The purpose of this study was to utilize a novel functional test system to facilitate determining the time of return to sports following ACL reconstruction. METHODS: Sixty-nine patients with unilateral ACL reconstruction were included in this pilot study. All the patients performed a standardized test battery consisting of one- and two-legged stability tests, counter movement jumps, speedy jumps, plyometric jumps and a quick feed test. The first test was administered on average 170.7 ± 75.1 days post-operatively, and the retest was administered on average 239.1 ± 79.7 days post-operatively. The values of the subtests were compared with the normative data of healthy gender- and age-matched controls to determine the functional capacities of patients following ACL reconstruction. RESULTS: After the first and second test, 15.9 and 17.4 % of the patients met the criteria for a "return to non-competitive sports". One patient fulfilled the criteria for a "return to competitive sports" after the second test battery. The most limiting factor was a poor LSI value of <90 % if the dominant leg was involved and <80 % if the non-dominant leg was involved. CONCLUSION: This test battery demonstrates that, in terms of neuromuscular abilities, most patients, compared to healthy controls, are most likely not ready for a safe return to sports, even 8 months post-operatively. This should be considered in the future to determine when it is safe to return to sports and should avoid a premature return to competitive sports. LEVEL OF EVIDENCE: III.

Omega-3 supplementation alters mitochondrial membrane composition and respiration kinetics in human skeletal muscle.

Studies have shown increased incorporation of omega-3 fatty acids into whole skeletal muscle following supplementation, although little has been done to investigate the potential impact on the fatty acid composition of mitochondrial membranes and the functional consequences on mitochondrial bioenergetics. Therefore, we supplemented young healthy male subjects (n = 18) with fish oils [2 g eicosapentaenoic acid (EPA) and 1 g docosahexanoic acid (DHA) per day] for 12 weeks and skeletal muscle biopsies were taken prior to (Pre) and following (Post) supplementation for the analysis of mitochondrial membrane phospholipid composition and various assessments of mitochondrial bioenergetics. Total EPA and DHA content in mitochondrial membranes increased (P < 0.05) ∼450 and ∼320%, respectively, and displaced some omega-6 species in several phospholipid populations. Mitochondrial respiration, determined in permeabilized muscle fibres, demonstrated no change in maximal substrate-supported respiration, or in the sensitivity (apparent Km) and maximal capacity for pyruvate-supported respiration. In contrast, mitochondrial responses during ADP titrations demonstrated an enhanced ADP sensitivity (decreased apparent Km) that was independent of the creatine kinase shuttle. As the content of ANT1, ANT2, and subunits of the electron transport chain were unaltered by supplementation, these data suggest that prolonged omega-3 intake improves ADP kinetics in human skeletal muscle mitochondria through alterations in membrane structure and/or post-translational modification of ATP synthase and ANT isoforms. Omega-3 supplementation also increased the capacity for mitochondrial reactive oxygen species emission without altering the content of oxidative products, suggesting the absence of oxidative damage. The current data strongly emphasize a role for omega-3s in reorganizing the composition of mitochondrial membranes while promoting improvements in ADP sensitivity.

Challenges in modelling the reaction chemistry of interstellar dust.

Studies aiming to understand the physicochemical properties of interstellar dust and the chemical reactions that occur on and in it have traditionally been the preserve of astronomical observation and experimental attempts to mimic astronomically relevant conditions in the laboratory. Increasingly, computational modelling in its various guises is establishing a complementary third pillar of support to this endeavour by providing detailed insights into the complexities of interstellar dust chemistry. Inherently, the basis of computational modelling is to be found in the details (e.g. atomic structure/composition, reaction barriers) that are difficult to probe accurately from observation and experiment. This bottom-up atom-based theoretical approach, often itself based on deeper quantum mechanical principles, although extremely powerful, also has limitations when systems become too large or complex. In this Perspective, after first providing a general background to the current state of observational-based knowledge, we introduce a number of computational modelling methods with reference to recent state-of-the-art studies, in order to highlight the capabilities of such approaches in this field. Specifically, we first outline the use of computational chemistry methods for dust nucleation, structure, and individual reactions on bare and icy dust surfaces. Later, we review kinetic modelling of networks of reactions relevant to dust chemistry and how to take into account quantum tunnelling effects in the low temperature reactions in the interstellar medium. Finally, we point to the future challenges that need to be overcome for computational modelling to provide even more detailed and encompassing perspectives on the nature and reaction chemistry of interstellar dust.

The impact of recent advances in laboratory astrophysics on our understanding of the cosmos.

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena-the radiation and particle spectra we observe-have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.

Trisomic hemopoietic stem cells of fetal origin restore hemopoiesis in lethally irradiated mice.

Autosomal trisomy in the mouse is invariably associated with fetal or early postnatal death. Hemopoietic stem cells from fetuses trisomic for chromosome 12 or 19 can be rescued by transplantation into lethally irradiated mice. These trisomic cells restore hemopoiesis, including lymphopoiesis, in the irradiated mice and establish a permanent and almost complete engraftment. There is no evidence that hemopoietic cells with trisomy 12 or 19 are cytogenetically unstable.

[Anterolateral stabilization using the modified Lemaire technique for ACL deficiency]. / Anterolaterale Stabilisierung mittels modifizierter Lemaire-Plastik bei insuffizientem vorderem Kreuzband.

OBJECTIVE: Treatment of persistent anterolateral knee instability. INDICATIONS: Subjective/objective (rotational) instability of the knee after anatomic anterior cruciate ligament (ACL) reconstruction. ACL re-rupture including special demands (e.g., high-performance athletes, hyperlaxity) RELATIVE CONTRAINDICATIONS: Osteoarthritis, additional instability of the knee, which should be treated independently; non-anatomic ACL reconstruction with persisting instability should be treated first with anatomic ACL reconstruction. ABSOLUTE CONTRAINDICATIONS: General contraindications for surgery (e. g. septic arthritis), acute irritation of the affected knee. SURGICAL TECHNIQUE: Supine position. Incision along the proximal lateral femoral epicondyle. Marking of the needed width and length of the iliotibial band (ITB) graft. Passing the ITB graft underneath the lateral collateral ligament. Find and mark the isometric point for fixation next to the lateral femoral epicondyle. Fixation of the ITB graft. Layered wound closure. POSTOPERATIVE MANAGEMENT: Knee brace for at least 6 weeks. Range of motion (RoM): from postoperative day 1: flexion-extension 90-0-0°; first 2 weeks after surgery: partial weight bearing (20 kg). RESULTS: An anterolateral extra-articular reconstruction may reduce a persistent anterolateral rotatory instability as well as the re-rupture rate following ACL reconstruction with good patient-reported short-term outcomes. Based on current (biomechanical) data, anterolateral tenodesis seems to be superior to a reconstruction of the anterolateral ligament. If a tenodesis is performed, the graft should be fixed in an isometric position, with neutral rotation of the knee and low graft tension to avoid extraphysiologic load within the lateral compartment. Indications for such a procedure may include a high-grade pivot shift or revision ACL reconstruction as well as a persistent anterolateral rotatory instability following anatomic ACL reconstruction.

Effect of concentration of D,L-2-difluoromethylornithine on murine mammary carcinogenesis.

The appearance of chemically induced mammary gland carcinomas in virgin female Sprague-Dawley rats was blocked by the administration of D,L-2-difluoromethylornithine (DFMO) in drinking water during the stage of tumor promotion. Rats were given injections s.c. at 50 days of age with either 35 mg of 1-methyl-1-nitrosourea (MNU) per kg of body weight or the 0.9% NaCl solution in which the carcinogen was dissolved. At 57 days of age, the rats were each randomly allocated to one of 14 treatment groups. Ten groups (five solvent treated and five MNU treated) were assigned to treatments consisting of 0.00, 0.0625, 0.125, 0.25, or 0.50% (w/v) solution of DFMO in their drinking water; two MNU-treated groups were placed on or removed from DFMO treatment (0.5%; w/v) at 90 days post-carcinogen exposure; and two carcinogen-treated groups received either putrescine (0.5-g/kg diet) or putrescine and DFMO (0.5%; w/v) throughout the experiment. The study was terminated 183 days after carcinogen treatment. All doses of DFMO exerted a protective effect against the induction of mammary cancer; however, only the feeding of the 0.125% and the 0.5% solutions of DFMO resulted in a significant reduction in cancer incidence. The average number of cancers per rat was reduced, and cancer-free time was extended at all concentrations of DFMO. The protective effect of DFMO was sustained following withdrawal of treatment at 90 days post-MNU injection. Feeding putrescine in conjunction with DFMO treatment partially blocked the inhibitory activity of DFMO. DFMO treatment did not affect food or water intake; body weight gain; the weight of ovaries, uterus, adrenal glands, liver, kidney, or spleen; or the periodicity of the estrous cycle. These data provide evidence of an inhibitory effect of DFMO against mammary cancer induced by MNU which cannot be attributed to a systemic toxic effect of this compound.

Degeneration and atrophy of the thymus of lethally irradiated dogs, rescued by transfusion of cryopreserved autologous blood leukocytes.

Dogs exposed to a fatal radiation dose of 12 Gy were rescued by transfusion of autologous blood leukocytes. A severe acute and long-lasting damage to the thymus was observed. The acute damage, as observed on the tenth day, consisted of a marked reduction in the number of lymphocytes, degeneration of Hassall's bodies, and hemorrhage. Long-term effects, observed several months after irradiation, were partial to total atrophy of the thymus. Regeneration, when it occurred, was limited to a few small isolated areas in which lymphopoiesis was supported by epithelial reticular cells. In contrast, the lymph nodes of all dogs had abundant cortical lymphopoiesis. The abundant hemopoiesis present in the marrow from the tenth day after irradiation until the end of the observation period should have provided sufficient circulating precursor cells to seed the thymus and regenerate the organ to the same extent as that observed in the other blood-forming organs. The impairment of lymphopoietic regeneration in the thymus seems to be due, therefore, to damage caused by irradiation on the specific stroma of the organ, which is not able to support such activity.

Exercise training normalizes mitochondrial respiratory capacity within the striatum of the R6/1 model of Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive cell loss in the striatum and cerebral cortex, leading to a decline in motor control and eventually death. The mechanisms promoting motor dysfunction are not known, however loss of mitochondrial function and content has been observed, suggesting that mitochondrial dysfunction may contribute to HD phenotype. Recent work has demonstrated that voluntary wheel running reduces hindlimb clasping in the R6/1 mouse model of HD, which we hypothesized may be due to preservation of mitochondrial content with exercise. Therefore, we investigated the role of chronic exercise training on preventing symptom progression and the loss of mitochondrial content in HD. Exercising R6/1 mice began training at 7 wks of age and continued for 10 or 20 wks. At 17 wks of age, R6/1 mice displayed a clasping phenotype without showing changes in mitochondrial respiration or protein content in either the cortex or striatum, suggesting mitochondrial dysfunction is not necessary for the progression of symptoms. At 27 wks of age, R6/1 mice demonstrated no additional changes in mitochondrial content or respiration within the cortex, but displayed loss of protein in complexes I and III of the striatum, which was not present in exercise-trained R6/1 mice. Mitochondrial respiration was also elevated in the striatum of R6/1 mice at 27 wks, which was prevented with exercise training. Together, the present study provides evidence that mitochondrial dysfunction is not necessary for the progression of hindlimb clasping in R6/1 mice, and that exercise partially prevents changes in mitochondrial content and function that occur late in HD.

Generation of effective cancer vaccines genetically engineered to secrete cytokines using adenovirus-enhanced transferrinfection (AVET).

Cancer vaccines are based on the concept that tumors express novel antigens and thus differ from their normal tissue counterparts. Such putative tumor-specific antigens should be recognizable by the immune system. However, malignant cells are of self origin and only poorly immunogenic, which limits their capability to induce an anticancer immune response. To overcome this problem, tumor cells have been isolated, genetically engineered to secrete cytokine gene products and administered as cancer vaccines. We used adenovirus-enhanced transferrinfection (AVET), which allows high-level transient transgene expression, to introduce cytokine gene expression vectors into murine melanoma cells. The efficiency of AVET makes laborious selection and cloning procedures obsolete. We administered such modified tumor cells as cancer vaccines to syngeneic animals and investigated their impact on the induction of anticancer immunity. We found that IL-2 or GM-CSF gene-transfected murine melanoma cells are highly effective vaccines. Both of these cytokine-secreting vaccines cured 80% of animals which bore a subcutaneous micrometastasis prior to treatment, and induced potent antitumor immunity. The generation of antitumor immunity by these cytokine-secreting vaccines requires three different steps: (1) tumor antigen uptake and processing by antigen-presenting cells (APCs) at the site of vaccination; (2) migration of these APCs into the regional lymph nodes where T-cell priming occurs; (3) recirculation of specific, activated T-cells that recognize distinct tumor load and initiate its elimination. Extending our previously reported studies, we have now comprehensively analysed the requirements for effective antitumor vaccination in animals. This may also become the basis for treatment of human cancer patients.

Liver ornithine decarboxylase during phenobarbital promotion of nitrosamine carcinogenesis.

The incidence of liver tumors induced in rats by N-diethylnitrosamine was increased by the feeding of phenobarbital. Liver ornithine decarboxylase activity did not increase in animals receiving phenobarbital in the diet, and the concentration of polyamines in the liver was similarly unchanged. No relationship between the promotion of N-nitrosamine-induced liver tumors by phenobarbital and the ornithine decarboxylase activity of the liver was indicated by these experiments.

Invasive pulmonary aspergillosis. MRI, CT, and plain radiographic findings and their contribution for early diagnosis.

A prospective study was conducted in 38 patients with nodular lesions on plain chest radiographs and the clinical suspicion of invasive pulmonary aspergillosis (IPA) to assess the diagnostic accuracy of magnetic resonance imaging (MRI) and computed tomography (CT). For early diagnosis of IPA (clinical signs and symptoms < 10 days), CT scans with demonstration of the halo sign had a high sensitivity (16/22) and specificity (8/8). Magnetic resonance imaging performed at the same time revealed a relatively higher sensitivity (22/22), but a very poor specificity (0/8). Gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA) enhanced images did not improve specificity. In the later course of infection (clinical signs and symptoms > 10 days), MRIs showed typical nodular target-like lesions with Gd-DTPA enhancement of the rim area that was not seen in the early course of the disease or in patients with Pseudomonas or staphylococcal infection. In conclusion, MRI findings are not as characteristic as the CT halo sign in diagnosing IPA in the early course of the disease, but the MRI target sign with Gd-DTPA enhancement of the rim area and the "reverse target" on T2-weighted images are strongly suggestive of IPA at a later stage of the disease.

Direct current influence on bone formation in titanium implants.

A dividable, titanium implant was inserted bilaterally in assembled form in the tibial metaphyses of adult rabbits. A titanium cathode was placed 5 mm proximal and a platinum-iridium anode 5 mm distally. The chamber on one side served as a non-stimulated control: on the other side the electrodes were connected to a constant current generator. Ten animals were treated with 5 microA, ten with 20 microA and ten with 50 microA. After three weeks the implants were removed, taken apart and the bone which had grown into two central canals of the chamber was collected for macroradiographic and computer-based numerical analysis. DC-stimulation with 50 microA did not result in any measurable increase of bone formation in the test implants compared to the controls. After stimulation with 5 or 20 microA, on the other hand, there was a statistically significant increase of osteogenesis, in spite of the fact that the electrodes were situated at some distance from the implant.

Relevance of trisomy 15 and other chromosome abnormalities in spontaneous AKR leukemia of mice with and without Robertsonian rearrangement.

The types and frequencies of chromosomal abnormalities in spontaneous AKR leukemia are presented: 45% to 58% of leukemic animals exhibit chromosome abnormalities; trisomy of chromosome 15 (Ts 15) occurs as the predominant chromosome abnormality not only in AKR/J but also in two AKR sublines characterized by the presence of two or one Robertsonian biarmed translocation Rb (6.15) of the chromosomes 6 and 15. Most often a triplication of the whole Rb (6.15) is found in Rb (6.15) homozygotes corresponding to combined Ts 6 + Ts 15. In the Rb (6.15) heterozygotes both trisomy of the biarmed (6.15) and of the acrocentric 15 is observed. Centric fission of the (6.15) chromosome is also possible in Rb (6.15) homozygotes resulting in Ts 15 without simultaneous Ts 6. Trisomies of other chromosomes are found either in addition to Ts 15 or as the only abnormality. If the data of Dofuku et al. (1975) are considered, abnormal karyotypes in AKR leukemia show Ts 15 in 90%, Ts 12 and Ts 17 in 18%-20%, and Ts 3, Ts 10 and Ts 14 in 8%-10% of the cases.

Susceptibility of mice reconstituted with trisomy 19 hematopoietic cells to infection with Rauscher leukemia virus.

Radiation chimeras with trisomy 19 hematopoietic cells were constructed to test the sensitivity of the trisomic hematopoietic system to infection with Rauscher leukemia virus: Hematopoietic cells from livers of trisomic fetuses were rescued by transplantation into lethally irradiated adult mice. These Ts 19 radiation chimeras show a stable and sufficiently long-lived trisomic hematopoiesis to allow experimental induction of Rauscher leukemia. Rauscher leukemia virus (RLV) induced a marked proliferation of erythroblasts in the spleens of Ts 19 mice and control chimeras within 3 weeks. The onset of erythroblast proliferation was significantly delayed in the Ts 19 mice, suggesting a smaller number of target cells for the RLV and/or reduced susceptibility of the target cells to RLV. Both Ts 19 and control chimeras developed nonlymphocytic leukemia 2-4 months after RLV injection. The course of leukemogenesis was similar in the two experimental groups. No numerical chromosome abnormalities associated with leukemogenesis were detectable in Ts 19 or control cells. The numbers of chromosomal sister chromatid exchanges 2 weeks after RLV injection were elevated to the same degree in both Ts 19 and control cells. Thus, cells with constitutional trisomy do not show increased chromosomal instability due to leukemogenesis.

Stimulation of rat sciatic nerve regeneration with pulsed electromagnetic fields.

The effects of pulsed electromagnetic fields (PEMF) on rat sciatic nerve regeneration after a crush lesion were determined. The rats were placed between a pair of Helmholtz coils and exposed to PEMF of frequency 2 Hz and magnetic flux density of 0.3 mT. A 4 h/day treatment for 3-6 days increased the rate of nerve regeneration by 22%. This stimulatory effect was independent of the orientation of the coils. Exposure times of 1 h/day-10 h/day were equally effective in stimulating nerve regeneration. Rats exposed to PEMF for 4 h/day for 7 days before crush, followed by 3 days after crush without PEMF, also showed significantly increased regeneration. This pre-exposure 'conditioning' effect suggests that PEMF influences regeneration indirectly.

The bone growth chamber for quantification of electrically induced osteogenesis.

A dividable titanium implant was inserted in the tibial metaphysis of rabbits, which permitted a numerical evaluation of ingrowing bone. The implant on the test side was used as cathode and was connected to a subcutaneously located stimulator delivering constant current of either 5 microA, 20 microA, or 50 microA. A corresponding control implant was inserted in the other tibia of the same animal and treated likewise, but was not connected to the stimulator. Distally to each implant, a platinum-iridium screw was inserted into the cortex and connected on the test side to the stimulator to serve as the anode. The results showed a 2.4-fold increase in bone formation with 5 microA. In the 20-microA group, there was 2.6-fold more bone in the test chambers. Direct current (DC) stimulation with 50 microA caused a clear decrease of bone volume, with an average of 48% less bone in the test implants. The results indicate that 5 and 20 microA direct current enhance bone ingrowth into a titanium implant that is used as a cathode. The osteogenesis seemed to be more pronounced in the case where the chamber was used as a cathode compared to earlier experiments in which the cathode was placed at a distance of 5 mm from the implant.