Chronic neuromuscular electrical stimulation of paralyzed hindlimbs in a rodent model

Neuromuscular electrical stimulation (NMES) can be used to activate paralyzed or paretic muscles to generate functional or therapeutic movements. The goal of this research was to develop a rodent model of NMES-assisted movement therapy after spinal cord injury (SCI) that will enable investigation of mechanisms of NMES-induced plasticity, from the molecular to systems level. Development of the model requires accurate mapping of electrode and muscle stimulation sites, the capability to selectively activate muscles to produce graded contractions of sufficient strength, stable anchoring of the implanted electrode within the muscles and stable performance with functional reliability over several weeks of the therapy window. Custom designed electrodes were implanted chronically in hindlimb muscles of spinal cord transected rats. Mechanical and electrical stability of electrodes and the ability to achieve appropriate muscle recruitment and joint angle excursion were assessed by characterizing the strength duration curves, isometric torque recruitment curves and kinematics of joint angle excursion over 6-8 weeks post implantation. Results indicate that the custom designed electrodes and implantation techniques provided sufficient anchoring and produced stable and reliable recruitment of muscles both in the absence of daily NMES (for 8 weeks) as well as with daily NMES that is initiated 3 weeks post implantation (for 6 weeks). The completed work establishes a rodent model that can be used to investigate mechanisms of neuroplasticity that underlie NMES-based movement therapy after spinal cord injury and to optimize the timing of its delivery.

High-repetition-rate chirped-pulse-amplification thin-disk laser system with joule-level pulse energy

We are reporting on the development of a diode-pumped chirped-pulse-amplification (CPA) laser system based on Yb:YAG thin-disk technology with a repetition rate of 100 Hz and output pulse energy in the joule range. The focus lies with the first results of the preamplifier--a regenerative amplifier (RA) and a multipass amplifier (MP). The system consists of a front end including the CPA stretcher followed by an amplifier chain based on Yb:YAG thin-disk amplifiers and the CPA compressor. It is developed in the frame of our x-ray laser (XRL) program and fulfills all requirements for pumping a plasma-based XRL in grazing incidence pumping geometry. Of course it can also be used for other interesting applications. With the RA pulse energies of more than 165 mJ can be realized. At a repetition rate of 100 Hz a stability of 0.8% (1sigma) over a period of more than 45 min has been measured. The optical-to-optical efficiency is 14%. The following MP amplifier can increase the pulse energy to more than 300 mJ. A nearly bandwidth-limited recompression to less than 2 ps could be demonstrated.

Activity-dependent plasticity in spinal cord injury

The adult mammalian central nervous system (CNS) is capable of considerable plasticity, both in health and disease. After spinal neurotrauma, the degrees and extent of neuroplasticity and recovery depend on multiple factors, including the level and extent of injury, postinjury medical and surgical care, and rehabilitative interventions. Rehabilitation strategies focus less on repairing lost connections and more on influencing CNS plasticity for regaining function. Current evidence indicates that strategies for rehabilitation, including passive exercise, active exercise with some voluntary control, and use of neuroprostheses, can enhance sensorimotor recovery after spinal cord injury (SCI) by promoting adaptive structural and functional plasticity while mitigating maladaptive changes at multiple levels of the neuraxis. In this review, we will discuss CNS plasticity that occurs both spontaneously after SCI and in response to rehabilitative therapies.

Determination of culprit lesion in patients undergoing elective percutaneous coronary intervention by myocardial perfusion imaging

The aim of this study was to determine and localize culprit lesion by myocardial perfusion imaging (MPI) in cases of angiographically detected coronary narrowing >or= 75% of at least one coronary artery.

MATERIAL AND METHODS

One hundred and thirty-two (132) patients with angiographically detected significant coronary narrowing (>or= 75% luminal stenosis of at least one major coronary artery) were studied. All the patients submitted MPI (99m)Tc-MIBI, with pharmacologic dipyridamole stress protocol with concomitant low level bicycle exercise 50W (DipyEX). We measured relative uptake (99m)Tc-MIBI for each myocardial segment using short-axis myocardial tomogram study. A 5-point scoring system was used to assess the difference between uptake degree in stress and rest studies for the same segments, and we created two indices: Sum reversibility score (SRS), Index of sum reversibility score (ISRS).

RESULTS

A total of 396 vascular territories (2244 segments) were analyzed before elective percutaneous coronary intervention (ePCI). Overall sensitivity, specificity and accuracy using SRS were 90.2%, 87.5%, and 89.4%, with a positive predictive value of 94.1%. Overall sensitivity, specificity, and accuracy using ISRS were 94.4%, 90.6%, 93.2% and the positive predictive value was 95.7%.

CONCLUSION

DipyEX MPI with the two indices created, SRS and ISRS, significantly improves sensitivity, specificity and accuracy in the determination and localization of culprit lesions in patients undergoing elective PCI.

Adaptive control of movement for neuromuscular stimulation-assisted therapy in a rodent model

Neuromotor therapy after spinal cord or brain injury often attempts to utilize activity-dependent plasticity to promote functional recovery. Neuromuscular electrical stimulation that activates paralyzed or paretic muscles may enhance passive assistance therapy by activating more muscle mass and enriching the sensory pattern with appropriately timed muscle spindle activation. To enable studies of activity-dependent plasticity, a rodent model for stimulation-assisted locomotor therapy was developed previously. To be effective, however, such a system must allow lengthy sessions of repetitive movements. In this study, we implemented an adaptive pattern generator/pattern shaper (PG/PS) control system for a rodent model of neuromotor therapy and evaluated its ability to generate accurate and repeatable hip movements in lengthy sessions by adjusting the activation patterns of an agonist/antagonist muscle pair. In 100-cycle movement trials, the PG/PS control system provided excellent movement tracking (<<10% error), but stimulation levels steadily increased to account for muscle fatigue. In trials using an intermittent movement paradigm (100 sets of five-cycle bouts interspersed by 20-s rest periods), excellent performance (<<8% error) was also observed with less stimulation, thus indicating reduced muscle fatigue. These results demonstrate the ability of the PG/PS control system to utilize an agonist/antagonist muscle pair to control movement at a joint in a rodent model. The demonstration of repeatable movements over lengthy intermittent sessions suggests that it may be well suited to provide efficient neuromotor therapy.

Insulin glargine maintains equivalent glycemic control and better lipometabolic control than NPH insulin in type 1 diabetes patients who missed a meal

Our goal was to investigate blood glucose and lipometabolism control in type 1 diabetes patients who missed breakfast and the accompanying insulin injection of NPH insulin (NPH) or insulin glargine (glargine) as part of a basal-bolus regimen. This was a multi-center, open-label, controlled study in adults (> or =18 years) with HbA (1c)< or =11.5% on insulin therapy with NPH as basal insulin. Patients were randomized to receive prandial insulin plus either bedtime glargine (n=28) or NPH (n=32). Insulin was titrated to target fasting blood glucose levels 80-130 mg/dl at 06:00-07:00. Patients had no intake of insulin or food between 22:00 and 12:00 the next day. The change in blood glucose levels (07:00-11:00) was similar (27.5 mg/dl vs. 35.4 mg/dl), but the mean blood glucose level was higher with glargine vs. NPH at 22:00 (158.2 mg/dl vs. 130.2 mg/dl). During the period without insulin or food intake, blood glucose decreased with glargine (-25.8 mg/dl) and increased with NPH (+9.1 mg/dl; p=0.0284). Nonesterified fatty acid (07:00 and 09:00-12:00) and beta-hydroxybutyrate (07:00 and 10:00-12:00) levels were lower with glargine vs. NPH (both p<0.05). For patients who miss a morning meal, glargine is associated with maintained glycemic and lipometabolic control compared with NPH insulin.

Adenosine stress protocols for nuclear cardiology imaging

The treadmill test combined with myocardial perfusion imaging (MPI) is a commonly used technique in the assessment of coronary artery disease (CAD). However, there is a group of patients who may not be able to undergo the treadmill test. Pharmacologic stress testing is increasingly utilized for stress perfusion imaging and currently accounts for nearly 40% of all nuclear stress testing [8]. The aim of this study was the introduction of adenosine stress protocols in our nuclear laboratory, and the following, recording and comparing of the frequency and severity of side-effects.

METHODS

We performed two kinds of adenosine stress protocols on 186 patients who underwent MPI with radiotracer 99mTc-sestamibi: 1st: 47 patients underwent AdenoSCAN abbreviated protocol IV. adenosin 140microg/kg/min for 3 minutes; 2nd: AdenoEX combined with low level 50W bicycle exercise in 139 patients. We followed and compared side-effects (minor and major events) between AdenoSCAN and AdenoEX protocol, and established an adequate time for imaging of both protocols.

RESULTS

Compared with AdenoSCAN, AdenoEX protocol was tolerated by all patients; it reduced all side-effects and improved image quality. Using AdenoEX protocol we found that the heart-to-liver ratio was significantly better, and we established a time of imaging of 15 minutes after stress, compared to the AdenoSCAN time of imaging which was a minimum of 45 minutes after stress.

CONCLUSION

This study gives advatages to AdenoEX protocol, because it had fewer side-effects, improved patients' tolerance, improved image quality, and enhanced efficiency and throughput given the opportunity for earlier imaging.

Absorption of ultrashort laser pulses in strongly overdense targets

Absorption measurements on solid conducting targets have been performed in s and p polarization with ultrashort, high-contrast Ti:sapphire laser pulses at intensities up to 5x10{16}W/cm{2} and pulse duration of 8 fs. The particular relevance of the reported absorption measurements lies in the fact that the extremely short laser pulse interacts with matter close to solid density during the entire pulse duration. A pronounced increase of absorption for p polarization at increasing angles is observed reaching 77% for an incidence angle of 80 degrees . Simulations performed using a 2D particle in cell code show a very good agreement with the experimental data for a plasma profile of L/lambda approximately 0.01.

Long-term weight loss effects on all cause mortality in overweight/obese populations

This systematic review assesses the long-term effectiveness of weight loss on all cause mortality in overweight/obese people. Medline, Embase and Cinahl were searched (1966-2005). Cohort studies and trials on participants with body mass index > or =25 kg m(-2), with weight change and mortality with > or =2-year follow-up, were included finally identifying 11 papers based on eight studies. There may be gender differences in the benefits for all cause mortality. The impact of weight loss in men on mortality was not clear with some studies indicating weight loss to be detrimental, while a recent cohort study showed benefits, if it were a personal decision. Other studies with no gender separation had similarly mixed results. However, one study indicated that overweight/obese women with obesity-related illness, who lost weight intentionally within 1 year, had significantly reduced mortality rates of 19-25%. In contrast, studies of overweight/obese diabetics irrespective of gender showed significant benefit of intentional weight loss on mortality in a meta-analysis, hazard ratios = 0.75 (0.67-0.83). There is some evidence that intentional weight loss has long-term benefits on all cause mortality for women and more so for diabetics. Long-term effects especially for men are not clear and need further investigation.

Neuromuscular electrical stimulation induced forelimb movement in a rodent model

Upper extremity neuromuscular electrical stimulation (FNS) has long been utilized as a neuroprosthesis to restore hand-grasp function in individuals with neurological disorders and injuries. More recently, electrical stimulation is being used as a rehabilitative therapy to tap into central nervous system plasticity. Here, we present initial development of a rodent model for neuromuscular stimulation induced forelimb movement that can be used as a platform to investigate stimulation-induced plasticity. The motor points for flexors and extensors of the shoulder, elbow, and digits were identified and implanted with custom-built stimulation electrodes. The strength-duration curves were determined and from these curves the appropriate stimulation parameters required to produce consistent isolated contraction of each muscle with adequate joint movement were determined. Using these parameters and previous locomotor EMG data, stimulation was performed on each joint muscle pair to produce reciprocal flexion/extension movements in the shoulder, elbow, and digits, while 3D joint kinematics were assessed. Additionally, co-stimulation of multiple muscles across multiple forelimb joints was performed to produce stable multi-joint movements similar to those observed during reach-grasp-release movements. Future work will utilize this model to investigate the efficacy and underlying mechanisms of forelimb neuromuscular stimulation therapy to promote recovery and plasticity after neural injury in rodents.

An experimental study of the biomechanical stability of ultrasound-activated pinned (SonicWeld Rx+Resorb-X) and screwed fixed (Resorb-X) resorbable materials for osteosynthesis in the treatment of simulated craniosynostosis in sheep

We compared a conventional resorbable screw osteosynthesis with a resorbable, ultrasound-activated pin osteosynthesis, and studied mechanical load capacity and operative handling. This new form of osteosynthesis aims to reduce operation times, and to avoid torque loads and screw fractures to achieve stability. A sheep craniotomy model simulated an operation for dysmorphia on an infant skull. Two rectangular craniotomies of equal size were created in 13 lamb skulls, and each refixed by different means: the first by mesh and 20 screws, and the second by mesh with 20 pins inserted with ultrasound activation. All osteosynthesis material consisted of resorbable amorphous poly-(d,l)-lactide (PDLLA) (Resorb-X, KLS Martin, Tuttlingen, Germany). The insertion time was recorded. The animals were killed at different times, and areas of the healing skull including the plates and pins or screws were removed and divided into sections, which were then tested. In total 74 pin-fixed and 77 screw-fixed samples were obtained. Bending and tensile tests were used to simulate different forms of loading. The time required for the insertion of pins was significantly shorter than for screws. The mechanical tests showed differences in the stability of the bond between the osteosynthesis plate and bone that depended on the osteosynthesis system and the length of time it was in the animal. The pin osteosynthesis gave a stable mechanical load capacity, which was significantly different from that of screw osteosynthesis. Advantages of ultrasound-assisted, resorbable, pin osteosynthesis, include optimum operative handling, reduced insertion time, avoidance of fractures of the fixation elements and higher three-dimensional load capacity.

Unique gene structure and paralogy define the 7D-cadherin family

Cadherins are Ca2+-dependent transmembrane glycoproteins crucial for cell-cell adhesion in vertebrates and invertebrates. Classification of this superfamily due to their phylogenetic relationship is currently restricted to three major subfamilies: classical, desmosomal and protocadherins. Here we report evidence for a common phylogenetic origin of the kidney-specific Ksp- (Cdh16) and the intestine-specific LI-cadherin (Cdh17). Both genes consist of 18 exons and the positions of their exon-intron boundaries as well as their intron phases are perfectly conserved. We found an extensive paralogy of more than 40 megabases in mammals as well as teleost fish species encompassing the Ksp- and LI-cadherin genes. A comparable paralogy was not detected for other cadherin gene loci. These findings suggest that the Ksp- and LI-cadherin genes originated by chromosomal duplication early during vertebrate evolution and support our assumption that both proteins are paralogues within a separate cadherin family that we have termed 7D-cadherins.

Salivary cortisol measurement--a reliable method for the diagnosis of Cushing's syndrome

The measurement of cortisol in saliva is becoming more widely accepted as a screening test for the diagnosis of hypercortisolism. Since 1986, cortisol measurement in saliva has been continuously used in our department. In this study we compared salivary cortisol profiles from proven Cushing's disease patients with profiles from healthy subjects and obese children. The purpose was to evaluate the predictive value of the method for the diagnosis of hypercortisolism and to define cut-off levels to exclude or identify hypercortisolism. Cortisol in saliva was measured in 150 Cushing's disease patients (30 children, 120 adults, ranging from age 4-70), 100 healthy subjects (55 children, 45 adults, ranging from age 6-60), and 31 children (age 7-15) with an age-related body-mass-index above the 90th percentile. Generally, five saliva samples were taken over the day at 6:00-8:00 a.m., 11:00-12:00 a.m., 4:00-6:00 p.m., 7:00-8:00 p.m., and 10:00 p.m. The samples were measured using a radioimmuno-assay (INCSTAR Corporation, Stillwater, Minnesota, USA). For healthy subjects, morning levels of cortisol in saliva between 3-19 microg/l were found. These levels dropped to levels in between <1-11 microg/l at 11:00-12:00 a.m., <1-6 microg/l at 4:00-6:00 p.m., <1-4.5 microg/l at 7:00-8:00 p.m., and <1-2.9 microg/l at 10:00 p.m. The measured values showed a correlation with age, height, and weight. In Cushing's disease patients, the circadian salivary cortisol rhythm was missing, compared to healthy subjects. There was no significant difference in salivary cortisol levels or circadian rhythm between healthy or obese children. We found a high sensitivity for the detection of hypercortisolism at the 10:00 p.m. salivary cortisol measurement. The following, age dependent cut-off levels for salivary cortisol at 10:00 p.m. were calculated for the exclusion of hypercortisolism. Age 6-10: 1.0 microg/l (specificity 100%, sensitivity 87.5%); age 11-15: 1.7 microg/l (specificity 100%, sensitivity 100%); age 16-20: 1.6 microg/l (specificity 100%, sensitivity 76.2%); age 21-60: 1.6 microg/l (specificity 100%, sensitivity 90.9%) [corrected] For the proof of Cushing's syndrome, the following age-dependent cut-off levels at 10:00 p.m. were found: age 6-10: 1.9 microg/l (specificity 100%, sensitivity 80%); age 11-15: 1.7 microg/l (specificity 100%, sensitivity 100%); age 16-20: 2.5 microg/l (specificity 100%, sensitivity 84.2%); age 21-60: 1.9 microg/l (specificity 100%, sensitivity 97.6 %) [corrected] The cortisol assessment in saliva is a sensitive and reliable method to discriminate normocortisolemic from hypercortisolemic patients. From our view, the major advantages of this method are the reliability, non-invasiveness, and use in ambulatory patients.

Neuromechanical control of locomotion in the rat

Rodent models are being extensively used to investigate the effects of traumatic injury and develop and assess the mechanisms of repair and regeneration. We present quantitative assessment of two-dimensional (2D) kinematics of overground walking and for the first time three-dimensional (3D) joint angle kinematics of all four limbs during treadmill walking in intact adult female Long-Evans rats. Gait cycle with subphases and intralimb and interlimb cyclograms are presented. Phase relationships between joint angles on a cycle-by-cycle basis and interlimb footfalls are assessed using a simple technique. Electromyogram (EMG) data from major flexor and extensor muscles for each of the hindlimb joints and elbow extensor muscles of the forelimbs synchronized to the 3D kinematics are also obtained. Overground walking kinematics, provides information on base of support, stride length, and hindfoot rotation. Treadmill walking kinematics indicate primarily monophasic angle trajectories for the hip and shoulder joints, weak double peak patterns for the knee and elbow joints, and a prominent double peak pattern for the ankle joints. Maximum flexion of the knee during swing precedes that of the ankle, which precedes that of the hip. A mild exercise regimen over 8 weeks does not alter the kinematics. EMG activity indicates specific relationships of the neural activity to joint angle kinematics. We find that the ankle flexors as well as the hip and elbow extensors maintain constant burst duration with changing cycle duration. Data and techniques described here are likely to be useful for quantitative assessment of altered gait and neural control mechanisms after neurotrauma.