Isolation of chlorine-containing antibiotic from the freshwater cyanobacterium Scytonema hofmanni.

Scytonema hofmanni, a filamentous freshwater cyanobacterium (blue-green alga), produces secondary metabolites which inhibit the growth of other cyanobacteria and green algae. A rapid, qualitative assay for this inhibition has been developed with Synechococcus as the test organism. This assay procedure has led to the isolation and characterization of an antibiotic (named cyanobacterin) from Scytonema. The antibiotic has a molecular weight of 430 and an empirical formula of C23H23O6Cl and contains a gamma-lactone and a chlorinated aromatic nucleus. It inhibits the growth of various algae but has limited effect on nonphotosynthetic bacteria or protozoans and thus may have potential use as a specific algicide.

A neuroprotective herbal mixture inhibits caspase-3-independent apoptosis in retinal ganglion cells.

It was previously demonstrated that Menta-FX, a mixture of Panax quinquefolius L. (PQE), Ginkgo biloba (GBE), and Hypericum perforatum extracts (HPE), enhances retinal ganglion cell survival after axotomy. However, the mechanisms of neuroprotection remain unknown. The aim of this study is to elucidate the neuroprotective mechanisms of Menta-FX. Since PQE, GBE and HPE have all been observed to display anti-oxidative property, the involvement of anti-oxidation in Menta-FX's neuroprotective effect was investigated. Menta-FX lowered nitric oxide (NO) content in axotomized retinas without affecting nitric oxide synthase activity, suggesting that Menta-FX possibly exhibited a NO scavenging property. In addition, the effect of Menta-FX on the frequency of axotomy-induced nuclear fragmentation and caspase-3 activation was investigated. Menta-FX treatment significantly reduced nuclear fragmentation in axotomized retinas. Surprisingly, Menta-FX had no effect on caspase-3 activation, but selectively lowered caspase-3-independent nuclear fragmentation in axotomized retinal ganglion cells. In addition, inhibition of PI3K activity by intravitreal injection of wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor, completely abolished the neuroprotective effect of Menta-FX, indicating that Menta-FX's neuroprotective effect was PI3K-dependent. Data here suggest that Menta-FX displayed a PI3K-dependent, selective inhibition on a caspase-3-independent apoptotic pathway in axotomized RGCs, thus, highlighting the potential use of herbal remedies as neuroprotective agents for other neurodegenerative diseases.

The time effect of pressure on tissue viability: investigation using an experimental rat model.

An experimental rat model was used to investigate the time-pressure effect on tissue viability. External loading equivalent to 13.3 kPa (100 mm Hg) of pressure was applied to the greater trochanter and tibialis area of Sprague-Dawley rats using pneumatic indentors for duration of 6 hrs each day for 1 to 4 days. It was observed that postocclusive hyperemic responses were gradually increased at the trochanter throughout the 4 days of loading, whereas for the tibia there was a significant increase (P = 0.04) in postocclusive hyperemic flow between Days 2 and 3. In histologic evaluations, cutaneous tissue damage was observed at the trochanter area but not at the tibialis area after 2 consecutive days of load application. In contrast, degeneration of muscle cells characterized by numerous increases of nuclei occupying the central of the muscle fibers was observed after 2 days of load application at the tibialis. The situation was found to progress with time (P = 0.17). The presence of other histologic signs, including the internalization of peripherally located nuclei, replacement of muscle cells by fibrosis and adipose tissues, and the presence of pyknotic nuclei as well as karyorrhexis, confirmed that the affected tissues were damaged. These findings suggest that postocclusive hyperemia and the distress of tissues under loading could be closely related.

Mechanical effects of traction on lumbar intervertebral discs: A magnetic resonance imaging study.

BACKGROUND: Although traction has long been used for treating patients with low back pain (LBP), its effects are still inconclusive mainly because of limited high-quality evidence. OBJECTIVE: To provide evidence of the mechanism of traction on lumbar intervertebral discs. DESIGN: A quantitative approach with a repeated measurement protocol. METHOD: Nine participants (mean age = 22.1 ± 0.8 years) without any LBP history were recruited. Magnetic Resonance Images of the lumbar spine of each participant were recorded before and after 30 min of horizontal lying and directly after 30 min of horizontal traction of 42% body weight. The average, anterior, central, and posterior disc height and tilt angle of each lumbar disc and lumbar lordosis were measured. RESULTS: A significant increase in the average disc height for all lumbar discs, a significant reduction of lumbar lordosis and changes in tilt angle were observed after the application of 30 min of resting followed by 30 min of traction. A significant increase in the average disc height was observed only in lower lumbar discs after 30 min of traction. The increase in the posterior disc height was more apparent than that in the anterior disc height. CONCLUSIONS: Horizontal traction was evidently effective in increasing the disc height of lower lumbar levels, particularly in the posterior regions of the discs. Further evidence of the effects of traction of different modes, magnitudes, and durations on the change in disc height is required for proper control of traction applied to specific disc levels.

Effects of prolonged surface pressure on the skin blood flowmotions in anaesthetized rats--an assessment by spectral analysis of laser Doppler flowmetry signals.

The objective of this study is to assess the effect of prolonged surface compression on the skin blood flowmotion in rats using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. An external pressure of 13.3 kPa (100 mmHg) was applied to the trochanter area and the distal lateral tibia of Sprague-Dawley rats via two specifically designed pneumatic indentors. The loading duration was 6 hours/day for 4 consecutive days. Five frequency intervals were identified (0.01-0.04 Hz, 0.04-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. The results showed that (1) tissue compression following the above schedule induced significant decrease in the normalized amplitude in the frequency interval of 0.01-0.04 Hz both in the trochanter area (p < 0.001) and tibialis area (p = 0.023), (2) prolonged compression induced significant increase in the absolute amplitude (p = 0.004 for the trochanter area and p = 0.017 for the tibialis area) but significant decrease in the normalized amplitude (p = 0.023 for the trochanter area and p = 0.026 for the tibialis area) in the frequency interval of 0.15-0.4 Hz, and (3) at the tibialis area, the flowmotion amplitude (frequency interval 0.15-0.4 Hz) measured prior to the daily tissue compression schedule was found to be significantly higher on day 4 than the measurements obtained on day 1. However, this finding was not observed at the trochanter area. Our results suggested that prolonged compression might induce endothelial damage and affect the endothelial related metabolic activities.

Therapeutic ultrasound enhances medial collateral ligament repair in rats.

The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on medial collateral ligament healing. A total of 36 3-month-old male Sprague-Dawley rats with transected medial collateral ligaments were studied. Subjects were given 5-min pulsed US therapy (duty cycle; one application in 4 ms; 1:4) daily with different durations (1 day, 5 days and 10 days) and intensities (0, 0.5 and 2.3 W/cm2). After each treatment, the level of transforming growth factor beta-1 (TGF-beta1) of the ligament was measured. TGF-beta1 was not detected in the 1-day group. In the 5-day and 10-day groups, the levels of TGF-beta1 were significantly up-regulated in the high-dose subgroup (p < 0.05). The 10-day group also registered a significantly higher expression of TGF-beta1 than did the 5-day group (p < 0.05). The present findings suggest that pulsed US therapy may enhance ligament repair by up-regulating the extent of TGF-beta1 in a high-dose application. Long-term treatment with this therapy could obtain further improvement.

The Effect of Acupressure on Agitation and Salivary Cortisol in People with Dementia: A Pilot Study.

OBJECTIVES: This study aimed to identify the acupressure effect over time, compare the efficacy in different dosages, and identify feasibility issues with saliva sample collection and acupressure implementation in agitated nursing home residents with dementia. DESIGN: Time serial design with eight dosage-combination groups. SETTING: Three residential care homes (RCHs) in Hong Kong. PARTICIPANTS: Agitated RCH residents with dementia. INTERVENTIONS: Acupressure was performed for 9 minutes altogether on five acupoints: Fengchi (GB 20), Baihui (GV 20), Shenmen (HT 7), Niguan (PC 6), and Yingtang (EX-HN 3). Two frequencies (once and twice a day) and four durations (1, 2, 3, and 4 weeks) formed eight dosage combinations. OUTCOME MEASURES: The primary outcome was agitation, measured by the Cohen Mansfield Agitation Inventory. The secondary outcome was stress, measured by salivary cortisol. RESULTS: Twenty-four participants from three RCHs completed the study. Acupressure was successfully completed for 88% of total sessions, and 79.17% of participants completed more than 80% of expected sessions. The effect of acupressure on agitation onset was seen immediately at week 1 (p < 0.001), resurged at week 4 (p = 0.001), and was sustained until week 6 (p < 0.001). The effect on stress began immediately to a mild extent at week 1 (p = 0.011) and peaked at week 4 (p = 0.010). Acupressure was observed to show the largest effect when it was performed twice a day (p = 0.026) for 2 weeks (p = 0.005). Valid saliva samples were collected for 53.33% of participants. Hyposalivation caused this unsatisfactory yield of valid saliva samples. CONCLUSION: Acupressure can be conducted on agitated RCH residents with dementia, but low yield of saliva samples related to participants' hyposalivation is a problem. Preliminary findings suggest that acupressure is effective in reducing both agitation and stress. Its onset of effect was immediate, and the effect was sustained until 6 weeks after the intervention. The optimal dosage appears to be a course of acupressure twice a day for 2 weeks.

Electro-acupuncture potentiates the disulphide-reducing activities of thioredoxin system by increasing thioredoxin expression in ischemia-reperfused rat brains.

Reactive oxygen species can directly affect the conformation and activity of sulfhydryl-containing proteins by oxidation of their thiol moiety. During the process of ischemia-reperfusion, the thioredoxin (Trx) system (consisting of thioredoxin reductase (TR), Trx and NADPH) prevents susceptible proteins from this oxidative modification. Oxidative damage is one of the most damaging stress in ischemia. If oxidative stress could be minimized, the damage occurred will be minimized accordingly. We therefore investigated whether electroacupuncture (EA) treatment at Fengchi (GB20) or Zusanli (ST36) acupoints in post-ischemic rats could increase TR-related activities and Trx expression which would translate into maintaining the intact thiol moiety of susceptible proteins in the surrounding. Our results indicated that EA treatment at either acupoint increased the Trx expression in ischemic-reperfused brain tissues. Induced Trx expressed levels gradually increased from post-ischemia day 1 to day 4. Statistical analysis revealed that there was no observable difference in the effect of EA treatment at GB20 and ST36. Sham EA treatment did not induce any Trx expression. EA at either acupoint did not alter TR activities in both non-ischemic and ischemic-reperfused rat brains. Taken overall, our finding suggests that EA treatment at GB20 or ST36 could increase Trx expression which could minimize oxidative modifications of thiol groups of surrounding proteins.

Electroacupuncture provides a new approach to neuroprotection in rats with induced glaucoma.

OBJECTIVES: To investigate, using multifocal electroretinogram (mfERG), the effect of electroacupuncture (EA) on retinal function in rats with experimental glaucoma. DESIGN AND SUBJECTS: Glaucoma was induced in the right eyes of 15 adult female Sprague-Dawley rats by laser photocoagulation for three quarters of the perilimbal and episcleral vessels. The left eye of each rat was used as the control. The animals were divided into 3 groups: no treatment (non-EA control group), 2 Hz EA group, and 100 Hz EA group. EA treatment at different frequencies can produce different levels of analgesia and hence the effect of EA with different frequencies on glaucoma treatment was investigated. Both eyes of each rat in the EA experimental groups received 3 EA treatment sessions each week for 4 weeks. The retinal function was measured using mfERG after 4 weeks of EA treatment. RESULTS: There was no significant difference in the amplitude (both N1 trough and P1 peak) of mfERG firstorder kernel response between the treatment and control groups. In determining the waveform characteristics by the ratio of N1 amplitude to P1 amplitude (N/P ratio), obvious differences were found in the N/P ratio between the control eyes and the glaucoma eyes in the non-EA group and the 100 Hz EA treatment group, but similar values in the N/P ratio were observed between the control eyes and the glaucoma eyes in the 2 Hz EA treatment group. The waveform from the eyes with glaucoma was deformed in both the non-EA group and the 100 Hz EA group, but the waveform from the glaucomatous eye was preserved in the 2 Hz EA group. CONCLUSIONS: Application of EA at 2 Hz provides neuroprotection by preserving retinal function in rats with experimental glaucoma. Low frequency EA may be an alternative therapy in the treatment of glaucoma.

In vivo matrix microdamage in a naturally occurring canine fatigue fracture.

Greyhound central tarsal bone (CTB) from animals with (n = 11) and without CTB fatigue fracture (n = 15) was examined histologically for the presence, numerical density, and morphology of in vivo microdamage. Complete fracture of the right CTB is a common occurrence during dog racing, because this is the outside limb when running counterclockwise on a circular or oval track. The CTB consisted of both remodeled cortical bone and inner trabecular bone. Thickening and coalescence of trabeculae were observed, particularly dorsally and medially, causing reduction or elimination of the marrow void spaces. A band of tightly packed transverse osteons was also observed adjacent to the concave proximal joint surface. Typical linear microcracks were most often seen in remodeled cortical and trabecular bone and were often observed adjacent to vascular channels. In contrast, ultra-microcracking, represented by diffuse staining with basic fuchsin, was consistently observed in the plantar process around the attachment site for the plantar ligament complex. Dog status (fractured or intact) and side (left or right) both had a significant effect on microcrack density and microcrack surface density (p < 0.05). Microcrack density and microcrack surface density were increased in the right (fractured) CTB from greyhounds with CTB fracture. There was also a trend for side to have a significant effect on microcrack length, with microcrack lengths being higher in the right CTB of both intact and fractured dogs. These data support the general hypothesis that fatigue fracture occurs because of ongoing cyclic stresses after induction of reparative remodeling. Development of methods for biomechanical testing of small cuboidal bones should allow investigation of relationships between accumulation of loading cycles and bone weakening because of microdamage.

Aging and accumulation of microdamage in canine bone.

Fractures associated with minimal trauma are common in aged human beings. However, bone safety margins are better preserved in aged dogs, which are rarely affected with minimal trauma fractures. Although the hierarchical architecture of canine and human compact bone is similar, the precise reasons for this species difference are unclear. Cyclic loading of bone during normal daily activity leads to the formation of microcracks within the tissue matrix of compact bone. Using a standard bulk-staining technique with basic fuchsin, we examined calcified transverse sections of the mid-diaphysis of the canine humerus from dogs of varying ages. We found that the amount of microdamage and porosity increased exponentially with aging, although the increases were relatively small, compared with human bone. Gender (female, ovariohysterectomized female, male, castrated male) did not have a significant effect on the amount of microdamage or porosity in bone. Alterations to the local material properties of bone tissue, or alterations to the local tissue repair responses, may play a role in the accumulation of microdamage in bone with aging. Determination of osteocyte lacunar density (number of osteocyte lacunae per bone area) and activation frequency (number of actively remodeling osteons per bone area per year) indicated that these variables declined exponentially with aging. There also was a trend for bone from dogs with low osteocyte lacunar density to have a higher microcrack density, but not higher porosity. Furthermore, bones with a high activation frequency did not accumulate microcracks or porosity. Taken together, these data suggest that, in canine bone, although a certain minimum number of osteocytes may be essential for an operational network that forms part of the signaling pathways that orchestrate repair of bone microdamage, increases in porosity with aging may not be directly associated with impaired function of the osteocyte network within bone.

Electroacupuncture reduces the extent of lipid peroxidation by increasing superoxide dismutase and glutathione peroxidase activities in ischemic-reperfused rat brains.

Reactive oxygen species can be scavenged by superoxide dismutase (SOD) and glutathione peroxidase (GPx). During ischemia-reperfusion, the normal functioning of these antioxidant enzymes may be insufficient for the prevention of oxidant-induced peroxidation of membrane lipids and hence cerebral infarction. We therefore investigated whether electroacupuncture (EA) treatment at Fengchi points in post-ischemic rats could increase the antioxidant enzyme activities and thereby reduce the extent of lipid peroxidation. The results indicated that while EA did not alter the antioxidant enzyme activities in non-ischemic normal rat brains, ischemia-reperfusion caused significant increases in SOD and GPx activities. EA treatment further increased the antioxidant enzyme activities in ischemic-reperfused brain tissues, with a concomitant decrease in the extent of lipid peroxidation. Our finding suggests that EA treatment at Fengchi reduced the extent of lipid peroxidation in ischemic-reperfused rat brains, possibly by increasing the activities of SOD and GPx.

Effectiveness of multiple pre-ischemia electro-acupuncture on attenuating lipid peroxidation induced by cerebral ischemia in adult rats.

Free radicals induced by cerebral ischemia-reperfusion injury can trigger lipid peroxidation, leading to the production of malondialdehyde (MDA) and 4-hydroxy-2(E)-nonenal (4-HNE). Post-ischemia electroacupuncture (EA) therapy was able to reduce extent of lipid peroxidation. However, the effect of pre-ischemic EA therapy has not been reported. In this study, we aim to investigate the effectiveness of pre-ischemic EA therapy on lipid peroxidation in the rat ischemic injury model. Four groups of Sprague-Dawley rats were designed: Placebo group (without EA therapy), NA group (EA therapy on non-acupoint), GB20 group (EA therapy on Fengchi), and ST36 group (EA therapy on Zusanli). Half of each group (n = 6) received 30-minute EA therapy for 3 times and the other half group for 18 times before the occlusion of right middle cerebral artery. Right brains were taken for determination of concentration of MDA and the total of MDA plus 4-HNE. We found that multiple pre-ischemia EA therapy at either GB20 or ST36 can effectively reduce the amount of MDA produced after MCA occlusion. However, this reduction was not observed in the total amount of MDA and 4-HNE. In conclusion, pre-ischemia EA can partly regulate the lipid peroxidation in cerebral ischemia, where both GB20 and ST36 have a similar beneficial effectiveness.

Therapeutic ultrasound improves strength of achilles tendon repair in rats.

The purpose of this study was to evaluate the effects of therapeutic ultrasound on structural properties and functional performance of Achilles tendon healing. Thirty Sprague-Dawley rats with surgical hemitransected Achilles tendon were studied. Ten were treated daily with 1 MHz continuous ultrasound at 1.0 W/cm2 for 4 min, 11 at 2.0 W/cm2 for 4 min and nine served as control without treatment. Achilles functional index (AFI) was recorded preoperatively and on postoperative days 3, 10 and 30. On day 30, the rats were sacrificed and Achilles tendons were tested for load-relaxation, stiffness and ultimate tensile strength (UTS). Results showed that UTS of both low-dose (p=0.023) and high-dose (p=0.002) groups was significantly greater than in controls. No significant differences in AFI (p=0.179), load-relaxation (p=0.205) and stiffness (p=0.842) were found among groups. These findings suggested that both low- and high-dose therapeutic ultrasound accelerate the healing process of ruptured tendon.

The effects of electro-acupuncture and transcutaneous electrical nerve stimulation on patients with painful osteoarthritic knees: a randomized controlled trial with follow-up evaluation.

OBJECTIVES: To examine the relative effectiveness of electro-acupuncture (EA) and transcutaneous electrical nerve stimulation (TENS) in alleviating osteoarthritic (OA)-induced knee pain. DESIGN: Single-blinded, randomized controlled study. SUBJECTS: Twenty-four (24) subjects (23 women and 1 man), mean age 85, were recruited from eight subsidized Care & Attention Homes for the elderly. INTERVENTIONS: Subjects were randomly assigned to the EA, TENS, or control groups. Subjects in the EA group (n = 8) received low-frequency EA (2 Hz) on two acupuncture points (ST-35, Dubi and EX-LE-4, Neixiyan) of the painful knee for 20 minutes. Subjects in the TENS group (n = 8) received low-frequency TENS of 2 Hz and pulse width of 200 micros on the same acupuncture points for 20 minutes. In both treatment groups, electrical treatment was carried out for a total of eight sessions in 2 weeks. Eight subjects received osteoarthritic knee care and education only in a control group. All subjects were evaluated before the first treatment, after the last treatment, and at 2-week follow-up periods. RESULTS: After eight sessions of treatment, there was significant reduction of knee pain in both EA group and TENS group, as measured by the Numeric Rating Scale (NRS) of pain (p < 0.01). Prolonged analgesic effect was maintained in the EA and the TENS groups at a 2-week follow-up evaluation. The Timed Up-and-Go Test (TUGT) score of the EA group was significantly lower than that of the control group (p < 0.05), but such change was not observed in the TENS group. CONCLUSIONS: Both EA and TENS treatments were effective in reducing OA-induced knee pain. EA had the additional advantage of enhancing the TUGT results as opposed to TENS treatment or no treatment, which did not produce such corollary effect.

The use of electro-acupuncture in conjunction with exercise for the treatment of chronic low-back pain.

OBJECTIVES: To determine the effect of a series of electro-acupuncture (EA) treatment in conjunction with exercise on the pain, disability, and functional improvement scores of patients with chronic low-back pain (LBP). DESIGN: A blinded prospective randomized controlled study. SUBJECTS AND INTERVENTIONS: A total of 52 patients were randomly allocated to an exercise group (n = 26) or an exercise plus EA group (n = 26) and treated for 12 sessions. OUTCOME MEASURES: Numerical Rating Scale (NRS), Aberdeen LBP scale, lumbar spinal active range of movement (AROM), and the isokinetic strength were assessed by a blinded observer. Repeated measures analysis of variance (R-ANOVA) with factors of group and time was used to compare the outcomes between the two groups at baseline (before treatment), immediately after treatment, 1-month follow-up, and 3-month follow-up. The level of significance was set at p = 0.05. RESULTS: Significantly better scores in the NRS and Aberdeen LBP scale were found in the exercise plus EA group immediately after treatment and at 1-month follow-up. Higher scores were also seen at 3-month follow-up. No significant differences were observed in spinal AROM and isokinetic trunk concentric strength between the two groups at any stage of follow-up. CONCLUSIONS: This study provides additional data on the potential role of EA in the treatment of LBP, and indicates that the combination of EA and back exercise might be an effective option in the treatment of pain and disability associated with chronic LBP.

Nonlinear muscle recruitment during intramuscular and nerve stimulation.

Future progress in neuromuscular prostheses will depend on developing techniques for stimulating paralyzed muscle, especially utilizing neuromuscular stimulation. We have found nonlinear force versus stimulus amplitude characteristic (recruitment) curves in the gastrocnemius-soleus-plantaris muscle group of the cat in response to stimulation of the tibial nerve near the muscle entry point. Such response characteristics are undesirable in neuromuscular control systems. Nonlinear recruitment curves usually consisted of two regions in which force increased linearly with stimulus amplitude, separated by a "plateau" region in which force was relatively constant. The two linear regions were associated with activation of separate neuromuscular compartments (lateral or medial gastrocnemius, plantaris, soleus, or subdivisions of those muscles). When the stimulated myoelectric responses from these compartments were plotted versus stimulus amplitude, the region of recruitment between threshold and saturation often did not appreciably overlap for different compartments, suggesting that the axons innervating those compartments were physically segregated within the nerve from axons innervating other compartments. Correlation coefficients between force and stimulated myoelectric response were very high (up to R2 = 0.99) when using a composite curve produced by averaging myoelectric response curves recorded from each of the active compartments. By dividing the tibial nerve into its component bundles or fascicles and stimulating each in turn, it was possible to show that individual bundles innervate non-overlapping groups of muscle compartments, and that recruitment of the nerve bundles over different threshold ranges could account for the nonlinear force/stimulus response curves initially observed. The presence of separate innervation of muscles or compartments by fascicles should be an important factor in designing functional neuromuscular stimulation (FNS) systems.

The VA-Cyberware lower limb prosthetics-orthotics optical laser digitizer.

Characterization of the residual limbs and limb segments of patients for prosthesis and orthosis design has principally been a subjective process, highly dependent upon the skill, level of training, and experience of the prosthetist/orthotist involved. Even with the application of computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies in prosthetics and orthotics, residual limb/limb segment characterization has remained substantially subjective and dependent upon prosthetist/orthotist skill, training, and experience. To eliminate the variations and errors that frequently occur because of this dependence, and to further quantify the patient measurement process, rehabilitation engineering researchers at the New York Department of Veterans Affairs Medical Center developed an optical laser digitizer for quantitative characterization of patients' residual limbs'/limb segments' spatial geometry and surface topography. The optical digitizer developed is described, and results of laboratory and clinical tests with the digitizer are presented. Examples showing the capability of the digitizer to accurately, rapidly, repeatably, and consistently capture the contours over the entire surfaces of the residual limbs of patients with below-knee (BK) and above-knee (AK) amputation, the lower limbs of orthotics patients, and the feet and ankles of pedorthics patients, are given. In addition, results of a comparative clinical study of optical digitization and standard prosthetics CAD plaster wrap cast electromechanical digitization of the residual limbs of subjects with BK and AK amputation are presented. The enhanced accuracy, repeatability, and consistency afforded by optical digitization are shown. Finally, areas for refinement of the optical digitizer's design, identified in the project's laboratory and clinical tests, are discussed.

Automated fabrication of mobility aids (AFMA): below-knee CASD/CAM testing and evaluation program results.

In 1988 the Department of Veterans Affairs Rehabilitation Research and Development Service, under the directorship of Margaret J. Giannini, M.D., began a nationally directed computer-aided design and computer-aided manufacturing (CAD/CAM) research program for the Automated Fabrication of Mobility Aids (AFMA). Under this program CAD/CAM research and development centers were established at the Prosthetics Research Study in Seattle, WA; at Northwestern University and the VA Lakeside Medical Center in Chicago, IL; and at the VA Medical Center and New York University Medical Center in New York, NY. These three centers conducted a collaborative program: (a) to introduce CAD/CAM technologies to prosthetists, physicians, therapists, and rehabilitation health care professionals in the United States; (b) to evaluate the feasibility of using CAD/CAM systems in clinical prosthetics settings; (c) to test and evaluate the University College London-Bioengineering Center's and the University of British Columbia-Medical Engineering Resource Unit's respective systems for the computer-aided design and computer-aided manufacture of prosthetic sockets (CASD/CAM) for below-knee amputees; and, (d) to obtain quantitative data for refinement of the CASD/CAM systems tested, and for the development of new, enhanced, more efficacious, and expedient systems.

Microcrack density and length in the proximal and distal metaphyses of the humerus and radius in dogs.

OBJECTIVE: To compare microcrack density and length in the proximal and distal metaphyses of the humerus and radius in dogs. SAMPLE POPULATION: Left humerus and radius from each of 10 dogs of medium to large size. PROCEDURE: Metaphyseal specimens were bulk stained in 1% basic fuchsin in graded alcohols and embedded in methylmethacrylate. For quantification of fatigue-induced microscopic damage, transverse sections were prepared from proximal and distal metaphyseal regions, and length and density of microcracks were determined, using light microscopy. RESULTS: Bone region, age, and body weight were not significantly associated with microcrack density or length. CONCLUSIONS AND CLINICAL RELEVANCE: The hypothesis that fatigue-induced injury (increased microcrack density and length) caused by cyclic loading associated with daily activity is greater in bone regions prone to development of osteosarcoma was not supported by data from this study.