Achilles tendon injury. 3. Structure of rabbit soleus muscles after immobilization at different positions

This investigation was designed to study the short and long term effects of inactivity on the fine structure of skeletal muscle tissue. Ankles of rabbits were unilaterally immobilized for one of three weeks. The knees were semiflexed and the feet were either in plantar or in dorsal flexed positions. The soleus muscles were examined immediately after removal of the plaster or after six months of observation. The muscle fibres, when immobilized in the slackened state, showed serious degenerative changes and Type 1 fibres, i.e. fibres lightly stained for myofibrillar ATPase at pH 9.4, were often necrotic. The fibre type ratio was changed when examined immediately after removal of the casts so that the relative number of Type 2 fibres was increased. If stretched, essentially normal morphology was seen. The contralateral soleus muscles, which were excessively weight-bearing during the plaster period, were characterized by small, sometimes necrotic, Type 2 fibres and splitting of Type 1 fibres. Whatever the reason for the structural changes it seems correct to point out to the surgeon that too much emphasis on tendon aspects implies certain risks. Overeagerness to obtain a safe way of unloading the tendon during the necessary period of immobilization after suture may result in longstanding damage to the muscle structure and, as a sequel, decreased strength.     

Morphometric analyses of human muscle fiber types

Fibers from the m. vastus lateralis of 10 middle-aged men were classified at ultrastructural level according to the appearance of the sarcomeric M-band. The Z-band widths had a two-peak distribution. One peak was due to type 1 fibers (mean 125 +/- 11 nm), the other to type 2 fibers. This latter could be separated into type 2A (101 +/- 9 nm) and type 2B (86 +/- 8 nm). About 83% of the fibers would have been correctly classified on the basis of the Z-band width alone. Mitochondrial volumes differed (type 1 5.6 +/- 0.8, 2A 4.0 +/- 0.8, and 2B 2.8 +/- 0.8%). However, only one third (37%) of the fibers would have been correctly classified if sorted according to this parameter. Mitochondrial volumes in the different fibers were correlated to mitochondrial enzymes, while fiber sizes and numbers were correlated to cytoplasmic variables. The correlations appeared mainly after a training program, suggesting that the relationships between structural and functional parameters are more obvious after adaptation to higher functional demands.     

Evaluation of 350 sciatic blocks in rheumatoid foot surgery

Summary Sciatic block with Mepivacaine (3–4 mg/kg) revealed successful in 91.9% of 340 rheumatoid patients with Keller/Clayton operation. In unsufficient blocks (8.1%) supplementary anesthesia by femoral nerve block, reblocking the sciatic nerve or local anesthetics secondarily gave good operating conditions. In three cases it was necessary to use additional spinal anesthesia. The concomitant sympathetic block gives an immediate cessation of sweating and a long lasting elevation of skin temperature.

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Zusammenfassung Blockierung des N. ischiadicus mit Mepivacaine (3–4 mg/kg) war erfolgreich in 91.9% von 340 Vorfußoperationen bei 340 Rheumapatienten. Bei nicht genügender Schmerzlosigkeit (8.1%) war es nötig auch den N. femoralis zu betäuben, die Ischiadicusblockierung zu repetieren oder eine zusätzliche lokale Betäubung zu verwenden. In 3 Fällen war es nötig mit Spinalanästhesie fortzusetzen. Die Ischiadicusbetäubung verursacht durch Blockierung der sympathischen Fasern auch eine unmittelbare Beendigung der Schweißsekretion und eine langdauernde Erhöhung der Hauttemperatur.

     

Functional development of the visual system in normal and protein deprived rats. III: Recordings from adult optic nerve in vitro

A persistent increase in the latencies of the visual evoked response recorded from the cortical surface of protein deprived adult rats was described recently (Sj?str?m et al. 1984). The morphological correlate to this alteration is unknown. Previous studies on malnourished rats have shown a reduction of axonal diameters and in the number of myelin lamellae in relation to axonal circumference, and hence the possibility of a decrease in fibre conduction velocity must be considered. In parallel study, we have established that changes in diameters and myelination of optic nerve fibres similar to those previously reported in malnourished rats are present in adult protein deprived (PD) rats (Conradi et al. 1985). In the present paper, recordings of optic nerves in vitro from adult normal (C) and protein deprived (PD) rats are described. The compound action potentials were very similar in the two groups. Three positive peaks were easily defined, probably corresponding to three functional groups of optic nerve fibers. No significant differences in amplitudes or conduction velocities for the three peaks were found between the C and PD rats. It is concluded that the increased latencies of the evoked response are not caused by a decrease in conduction velocity.     

Urinary bladder volume tracking using a Kalman filter

This study introduced the Kalman filter procedure for tracking urinary bladder filling from intermittent bladder volume measurements taken by an ultrasonic bladder volume monitor. The Kalman filter was based on a double integrator as a model for the bladder filling process between micturitions and included a procedure to reset the filter in the event of a micturition. The performance of the Kalman filter was evaluated experimentally using an ultrasonic bladder volume monitor on seven male urologic patients. During cystometry, saline was infused into the patient's bladder at a constant rate of 30 ml min⁻¹ until it was full, and the volume of the bladder was recorded every 30 s by the bladder volume monitor. The evaluation showed that the filter significantly improved the precision of the measured volumes in terms of mean absolute error by 4.2 ml (95% confidence interval: 0.7–7.7 ml) (p=0.025) without affecting the system accuracy, i.e slope (p=0.92) and intercept (p=0.32). Finally, the micturition reset procedure was verified using simulated data.     

Reduction in albuminuria with dapagliflozin cannot be predicted by baseline clinical characteristics or changes in most other risk markers

The sodium glucose co-transporter-2 inhibitor dapagliflozin has been shown to decrease urinary albumin-to-creatinine ratio (UACR). This effect, however, varies among individual patients. In this study, we assessed the baseline characteristics and concurrent changes in other cardiovascular risk markers that might be associated with UACR response to dapagliflozin. A pooled analysis of 11 phase 3 randomized, controlled clinical trials was performed. UACR change from baseline after 24 weeks treatment with dapagliflozin 10 mg/d in 531 patients with type 2 diabetes and UACR ≥30 mg/g at baseline was determined. UACR response was defined as >30% reduction from baseline at 24 weeks, whereas UACR non-response was defined as ≤30% reduction at 24 weeks. A total of 288 (54%) patients were classified as responders and 243 (46%) as non-responders. At 24 weeks, the UACR-adjusted mean change from baseline was −71.2% and 25.9% in responders and non-responders, respectively. Baseline characteristics were similar between both groups. Changes in HbA1c and body weight were comparable across groups. Responders showed a numerically larger reduction in estimated glomerular filtration rate and systolic blood pressure versus non-responders. UACR reduction to dapagliflozin is an individual characteristic that cannot be predicted by baseline clinical features or changes in metabolic variables. Whether UACR response would improve long-term renal and cardiovascular outcomes remains to be determined.     

Nej1 recruits the Srs2 helicase to DNA double-strand breaks and supports repair by a single-strand annealing-like mechanism

Double-strand breaks (DSBs) represent the most severe DNA lesion a cell can suffer, as they pose the risk of inducing loss of genomic integrity and promote oncogenesis in mammals. Two pathways repair DSBs, nonhomologous end joining (NHEJ) and homologous recombination (HR). With respect to mechanism and genetic requirements, characterization of these pathways has revealed a large degree of functional separation between the two. Nej1 is a cell-type specific regulator essential to NHEJ in Saccharomyces cerevisiae. Srs2 is a DNA helicase with multiple roles in HR. In this study, we show that Nej1 physically interacts with Srs2. Furthermore, mutational analysis of Nej1 suggests that the interaction was strengthened by Dun1-dependent phosphorylation of Nej1 serines 297/298. Srs2 was previously shown to be recruited to replication forks, where it promotes translesion DNA synthesis. We demonstrate that Srs2 was also efficiently recruited to DSBs generated by the HO endonuclease. Additionally, efficient Srs2 recruitment to this DSB was dependent on Nej1, but independent of mechanisms facilitating Srs2 recruitment to replication forks. Functionally, both Nej1 and Srs2 were required for efficient repair of DSBs with 15-bp overhangs, a repair event reminiscent of a specific type of HR called single-strand annealing (SSA). Moreover, absence of Rad51 suppressed the SSA-defect in srs2 and nej1 strains. We suggest a model in which Nej1 recruits Srs2 to DSBs to promote NHEJ/SSA-like repair by dismantling inappropriately formed Rad51 nucleoprotein filaments. This unexpected link between NHEJ and HR components may represent cross-talk between DSB repair pathways to ensure efficient repair.     

A histomorphometric comparison of the bone graft-titanium interface between interpositional and onlay/inlay bone grafting techniques

PURPOSE: To analyze the bone graft-implant interface of titanium microimplants (MIs) placed at the time of bone grafting or after a healing period of 6 months and retrieved after another 6 to 14 months of healing. Integration of MIs placed in interpositional bone grafts (IBGs) in conjunction with a Le Fort I osteotomy was compared with the integration of those placed in onlay/inlay bone grafts (OBGs). MATERIALS AND METHODS: The severely atrophied edentulous maxillae of 23 patients (14 women, 9 men) were restored with autogenous bone grafts (either IBG [n=8] or OBG [n=15]) and titanium implants. Six-month periods were allowed between grafting, implant placement, and abutment connection. The bone-implant interface was studied histologically with the use of unloaded titanium MIs. RESULTS: Sixty-eight MIs were either (1) placed simultaneously with grafting and retrieved after 6, 12, or 14 months or (2) placed after 6 months of healing and retrieved after another 6 to 8 months. Histomorphometry indicated equal degrees of osseointegration for the 2 intraoral reconstruction techniques when looking at bone-implant contact, bone area in threads, and newly formed bone (NFB) (Student t test for unpaired observations). There was a significant difference between simultaneous and delayed implant placement with respect to BIC and NFB (Student t test for paired observations). Three additional MIs placed in the nongrafted residual alveolar ridge and retrieved after 6 months showed significantly more bone in threads and NFB (Student t test for paired observations; P = .003 and P = .009, respectively) compared to MIs placed at graft placement (6 months' healing). DISCUSSION: Timing of implant placement appeared more important than healing time or surgical technique. The delayed approach resulted in better implant integration, probably because of the initial revascularization of the graft. CONCLUSIONS: Implant integration was similar in the IBG and OBG groups. Placement of MIs after an initial healing period of 6 months resulted in better integration than placement simultaneously with grafting.     

A Six-Community Prevention Trial to Reduce Alcohol and Drug Use–Related Problems in Sweden: Planning and Early Findings

The objective of this study was to evaluate a research and development project to reduce alcohol and drug use–related problems, conducted during 2003–2005, in six urban and rural municipalities in Sweden, Umeå, Kramfors, Solna, Kalmar, Laholm, and Lund. The development of alcohol and drug use trends and patterns will be followed through 2008 in the six targeted intervention communities and in the six matched control communities. The evaluation includes archival data, survey data, observational data, as well as process measures. The six communities have gradually reoriented their thinking about prevention from a single focus on youth activities to a broader approach involving the whole population. The project's and the study's limitations are noted and future needed research is suggested.