The decrease in population bone lead levels in Canada between 1993 and 2010 as assessed by in vivo XRF

Objective and Approach: A study, conducted in Toronto, Canada, between 2009 and 2011, measured the bone lead concentrations of volunteers aged 1-82 years using in vivo x-ray fluorescence (XRF) technology.

MAIN RESULTS

Bone lead levels were lower compared to Ontario in vivo XRF studies from the early 1990s. In adults, the slope of tibia lead content versus age was reduced by 36-56%, i.e. bone lead levels for a given age group were approximately half compared to the same age group 17 years prior. Further, bone lead levels of individuals fell over that time period. In 2010, an average person aged 57 years had a bone lead level approximately 1/3 less than their bone lead level age 40 years in 1993. Using this data, the half-lives of lead in the tibia were estimated as 7-26 years. Tibia lead levels were found to be low in children. The reduction in bone tibia content in children was not significant (p  =  0.07), but using data from additional north eastern US studies, there is evidence that childhood tibia stores are lower than in the 1990s.

SIGNIFICANCE

In vivo XRF analysis shows that there has been a reduction in the level of lead in bone in Canada over the last two decades. Public health measures have been very successful in reducing ongoing exposure to lead and in reducing bone lead stores.

National Institutes of Health Research Plan on Rehabilitation: NIH Medical Rehabilitation Coordinating Committee

One in five Americans experiences disability that affects their daily function because of impairments in mobility, cognitive function, sensory impairment, or communication impairment. The need for rehabilitation strategies to optimize function and reduce disability is a clear priority for research to address this public health challenge. The National Institutes of Health (NIH) recently published a Research Plan on Rehabilitation that provides a set of priorities to guide the field over the next 5 years. The plan was developed with input from multiple Institutes and Centers within the NIH, the National Advisory Board for Medical Rehabilitation Research, and the public. This article provides an overview of the need for this research plan, an outline of its development, and a listing of six priority areas for research. The NIH is committed to working with all stakeholder communities engaged in rehabilitation research to track progress made on these priorities and to work to advance the science of medical rehabilitation.This article is being published almost simultaneously in the following six journals: American Journal of Occupational Therapy, American Journal of Physical Medicine and Rehabilitation, Archives of Physical Medicine and Rehabilitation, Neurorehabilitation and Neural Repair, Physical Therapy, and Rehabilitation Psychology. Citation information is as follows: NIH Medical Rehabilitation Coordinating Committee. Am J Phys Med Rehabil. 2017;97(4):404-407.

Tacrolimus to Belatacept Conversion Following Hand Transplantation: A Case Report

Vascularized composite allotransplantation (VCA) has emerged as a viable limb replacement strategy for selected patients with upper limb amputation. However, allograft rejection has been seen in essentially all reported VCA recipients indicating a requirement for substantial immunosuppressive therapy. Calcineurin inhibitors have served as the centerpiece agent in all reported cases, and CNI-associated complications associated with the broad therapeutic effects and side effects of calcineurin inhibitors have been similarly common. Recently, belatacept has been approved as a calcineurin inhibitor replacement in kidney transplantation, but to date, its use in VCA has not been reported. Herein, we report on the case of a hand transplant recipient who developed recurrent acute rejection with alloantibody formation and concomitant calcineurin inhibitor nephrotoxicity, all of which resolved upon conversion from a maintenance regimen of tacrolimus, mycophenolate mofetil and steroids to belatacept and sirolimus. This case indicates that belatacept may be a reasonable maintenance immunosuppressive alternative for use in VCA, providing sufficient prophylaxis from rejection with a reduced side effect profile, the latter being particularly relevant for nonlife threatening conditions typically treated by VCA.

An experimental study investigating the ability of volunteers to identify squirrel species from tail–hair samples

Hair–tubes, collecting nape hairs, are widely used for establishing the presence of red (Sciurus vulgaris) and grey (Sciurus carolinensis) squirrels. However it is time–consuming and prone to identification errors. An alternative is to collect tail hairs from sticky pads on baited poles. However, there is no evidence concerning identification accuracy of tail hairs. This study reports an experiment in which subjects underwent a short training session before identifying hair samples from four species. There was a 96.5% correct identification rate for grey squirrel hairs, and 77.5% for red squirrels, which suggests that tail hairs collection may provide a quick, easy and accurate method of identification for both species.

Renal transplantation using belatacept without maintenance steroids or calcineurin inhibitors

Kidney transplantation remains limited by toxicities of calcineurin inhibitors (CNIs) and steroids. Belatacept is a less toxic CNI alternative, but existing regimens rely on steroids and have higher rejection rates. Experimentally, donor bone marrow and sirolimus promote belatacept's efficacy. To investigate a belatacept-based regimen without CNIs or steroids, we transplanted recipients of live donor kidneys using alemtuzumab induction, monthly belatacept and daily sirolimus. Patients were randomized 1:1 to receive unfractionated donor bone marrow. After 1 year, patients were allowed to wean from sirolimus. Patients were followed clinically and with surveillance biopsies. Twenty patients were transplanted, all successfully. Mean creatinine (estimated GFR) was 1.10 ± 0.07 mg/dL (89 ± 3.56 mL/min) and 1.13 ± 0.07 mg/dL (and 88 ± 3.48 mL/min) at 12 and 36 months, respectively. Excellent results were achieved irrespective of bone marrow infusion. Ten patients elected oral immunosuppressant weaning, seven of whom were maintained rejection-free on monotherapy belatacept. Those failing to wean were successfully maintained on belatacept-based regimens supplemented by oral immunosuppression. Seven patients declined immunosuppressant weaning and three patients were denied weaning for associated medical conditions; all remained rejection-free. Belatacept and sirolimus effectively prevent kidney allograft rejection without CNIs or steroids when used following alemtuzumab induction. Selected, immunologically low-risk patients can be maintained solely on once monthly intravenous belatacept.

Antimicrobial resistance of fecal indicators in disinfected wastewater

The main objective of the study was to assess the potential of three systems (UV irradiation, ozonation, and micro/ultrafiltration) operated in a pilot scale in removal of antimicrobial-resistant fecal bacteria from secondary effluent of the local wastewater treatment plant (700,000 population equivalent). The effectiveness of the processes was analysed using the removal ratio of fecal indicators (Escherichia coli and Enterococcus spp.). The susceptibility of fecal indicators to antimicrobial agents important in human therapy was examined. Resistance to nitrofurantoin and erythromycin was common among enterococci and followed by resistance to fluoroquinolones and tetracycline. Resistance to high-level aminoglycosides and glycopeptides was also observed. E. coli isolates were most frequently resistant to penicillins and tetracycline. The extended-spectrum beta-lactamase-producing E. coli was detected once, after ozonation. Substantial attention should be paid to the E. coli and enterococci resistant to three or more chemical classes of antimicrobials (MAR), which in general constituted up to 15 and 49% of the tested isolates, respectively. Although the applied methods were effective in elimination of fecal indicators (removal efficiency up to 99.99%), special attention has to be paid to the application of sufficient disinfection and operation conditions to avoid selection of antimicrobial resistant bacteria.

Medium-term performance and maintenance of SUDS: a case-study of Hopwood Park Motorway Service Area, UK

One of the main barriers to implementing SUDS is concern about performance and maintenance costs since there are few well-documented case-studies. This paper summarizes studies conducted between 2000 and 2008 of the performance and maintenance of four SUDS management trains constructed in 1999 at the Hopwood Park Motorway Service Area, central England. Assessments were made of the wildlife value and sedimentation in the SUDS ponds, the hydraulic performance of the coach park management train, water quality in all management trains, and soil/sediment composition in the grass filter strip, interceptor and ponds. Maintenance procedures and costs were also reviewed. Results demonstrate the benefits of a management train approach over individual SUDS units for flow attenuation, water treatment, spillage containment and maintenance. Peak flows, pond sediment depth and contaminant concentrations in sediment and water decreased through the coach park management train. Of the 2007 annual landscape budget of pounds 15,000 for the whole site, the maintenance costs for SUDS only accounted for pounds 2,500 compared to pounds 4,000 for conventional drainage structures. Furthermore, since sediment has been attenuated in the management trains, the cost of sediment removal after the recommended period of three years was only pounds 554 and, if the design is not compromised, less frequent removal will be required in future.

Kind strangers? Physicians through the eyes of Tennessee Williams

In Louisiana, Tennessee Williams is usually thought of as a famous denizen of the French Quarter or perhaps as our greatest playwright. Medicine rarely enters into it. Illness, however, particularly mental illness, shaped much of Williams' life and his work. The playwright had mixed feelings about physicians and their effect on his life and that of his close relations. These feelings worked their way into his plays. Through it all Williams gives a vivid, humorous, and deeply truthful image of the doctor-patient relationship in the first half of the twentieth century. Here we give a brief review of medicine in Williams' work.

Conservative lower back treatment reduces inhibition in knee-extensor muscles: a randomized controlled trial

BACKGROUND

Knee-joint pathologies, such as anterior knee pain (AKP), are associated with strength deficits and reduced activation of the knee extensors, which is referred to as muscle inhibition (MI). MI is thought to prevent full functional recovery, and treatment modalities that help to reduce or eliminate MI appear necessary for successful rehabilitation. Clinical observations suggest that AKP is typically associated with sacroiliac (SI) joint dysfunction. It is unknown whether SI-joint dysfunction contributes to knee-extensor deficits and whether correction of SI-joint dysfunction alleviates MI.

OBJECTIVE

The objective of this study was to assess whether conservative low back treatment reduces lower limb MI.

STUDY DESIGN

In a randomized, controlled, double-blind study the effects of conservative lower back treatment on knee-extensor strength and MI were evaluated in patients with AKP.

METHODS

Twenty-eight patients with AKP were randomly assigned to either a treatment or a control group. After a lower back functional assessment, the treatment group received a conservative treatment in the form of a chiropractic spinal manipulation aimed at correcting SI-joint dysfunction. The control group underwent a lower back functional assessment but received no joint manipulation. Before and after the manipulation or the lower back functional assessment, knee-extensor moments, MI, and muscle activation during full effort, isometric knee extensions were measured.

RESULTS

Patients showed substantial MI in both legs. Functional assessment revealed SI-joint dysfunction in all subjects (23 symptomatic and 5 asymptomatic). After the SI-joint manipulation, a significant decrease in MI of 7.5% was observed in the involved legs of the treatment group. MI did not change in the contralateral legs of the treatment group or the involved and contralateral legs of the control group. There were no statistically significant changes in knee-extensor moments and muscle activation in either group.

CONCLUSIONS

The results of this study suggest that SI-joint manipulation reduces knee-extensor MI. Spinal manipulation may possibly be an effective treatment of MI in the lower limb musculature.

Decrease in quadriceps inhibition after sacroiliac joint manipulation in patients with anterior knee pain

BACKGROUND

Evidence exists that conservative rehabilitation protocols fail to achieve full recovery of muscle strength and function after joint injuries. The lack of success has been attributed to the high amount of muscle inhibition found in patients with pathologic conditions of the knee joint. Clinical evaluation shows that anterior knee pain is typically associated with sacroiliac joint dysfunction, which may contribute to the muscle inhibition observed in this patient group.

OBJECTIVE

To assess whether sacroiliac joint manipulation alters muscle inhibition and strength of the knee extensor muscles in patients with anterior knee pain.

DESIGN AND SETTING

The effects of sacroiliac joint manipulation were evaluated in patients with anterior knee pain. The manipulation consisted of a high-velocity low-amplitude thrust in the side-lying position aimed at correcting sacroiliac joint dysfunction. Before and after the manipulation, torque, muscle inhibition, and muscle activation for the knee extensor muscles were measured during isometric contractions using a Cybex dynamometer, muscle stimulation, and electromyography, respectively.

PARTICIPANTS

Eighteen patients (mean age, 30.5 +/- 13.0 years) with either unilateral (n = 14) or bilateral (n = 4) anterior knee pain.

RESULTS

Patients showed substantial muscle inhibition in the involved and the contralateral legs as estimated by the interpolated twitch technique. After the manipulation, a decrease in muscle inhibition and increases in knee extensor torques and muscle activation were observed, particularly in the involved leg. In patients with bilateral anterior knee pain, muscle inhibition was decreased in both legs after sacroiliac joint adjustment.

CONCLUSIONS

Spinal manipulation might offer an interesting alternative treatment for patients with anterior knee pain and muscle inhibition. Because this clinical outcome study was of descriptive nature rather than a controlled design, biases might have occurred. Thus the results have to be verified in a randomized, controlled, double-blinded trial before firm conclusions can be drawn or recommendations can be made.

Spinal imaging and intervention: 1998

Imaging of the lumbar spine is the most common application of magnetic resonance (MR) imaging in many radiologic practices. MR imaging has replaced computed tomography (CT) and CT myelography as the primary mode of spinal imaging and has relegated myelography to a secondary role in the evaluation of lumbar spinal disorders. At the same time, however, it has become evident that the correlation between gross anatomic findings as depicted on MR images and the clinical signs and symptoms detected by the clinician may be lacking. Defining the precise anatomic source of patients' complaints on the basis of imaging studies must be approached judiciously because a significant proportion of the population has disc disease as depicted on imaging studies, yet many have no clinical findings.

In vivo comparison of scanning technique and wavelength in laser Doppler perfusion imaging: measurement in knee ligaments of adult rabbits

At present, there are only two laser Doppler perfusion imaging systems (LDIs) manufactured for medical applications: a 'stepwise' and a 'continuous' scanning LDI. The stepwise scanning LDI has previously been investigated and compared with coloured microsphere determined standardised flow. The continuous scanning LDI is investigated and compared with the stepwise scanning LDI for its ability to measure in vivo, hypoaemic, ligament tissue blood flow changes. The continuous scanning system was supplied with two lasers, red and near infrared (NIR), allowing for additional assessment of the effect of wavelength on imaging ligament perfusion. Perfusion images were obtained from surgically exposed rabbit medial collateral ligaments (MCL). Continuous and stepwise LDI scans were compared using correlation and linear regression analysis of image. averages and standard deviations. Using the same method of analysis, LDI measurements using red and NIR lasers indicated a high degree of correlation, at least over the ranges of perfusion assessed, indicating that red and NIR lasers measure similar regions of flow in the rabbit MCL. These experiments confirm that both LDI techniques provide a valid in vivo measure of dynamic changes in connective tissue perfusion and could have significant impact on the understanding and treatment of joint injury and arthritis.

Evaluation of laser Doppler imaging to measure blood flow in knee ligaments of adult rabbits

Laser Doppler imaging (LDI) is investigated as a novel method for in vivo ligament tissue blood flow determination. LDI output signal is obtained from surgically exposed rabbit medial collateral ligaments (MCL). The LDI signal is compared with simultaneously determined, coloured microsphere (CM)-derived standardised MCL blood flow. Correlation of LDI output with the CM flow data and a linear regression of 17 data points in nine rabbits (joint injured to provoke an acute vascular response in the tissues) indicate that LDI provides a reasonable estimate of MCL blood flow, at least over the ranges assessed. If properly calibrated, and given enough tissue-specific data points, LDI may have advantages over conventional, but more invasive, techniques. The potential clinical application of LDI technology to joint injury and arthritis research is discussed.

DNA index and ploidy distinguish normal human parathyroids from parathyroid adenomas and primary hyperplastic parathyroids

BACKGROUND

The goal of this study was to identify factors that might aid in diagnosis and intraoperative management of hyperparathyroidism.

METHODS

We analyzed biopsy specimens of 242 parathyroids from 159 patients by use of flow cytometry and image cytometry (ICM) for DNA index (DI), defined as the content of nuclear DNA compared with that expected for a DNA diploid standard, for proliferative index (PI), and for ploidy (diploid versus aneuploid or tetraploid).

RESULTS

True normal and normal parathyroids from patients with solitary adenomas were uniformly diploid. Abnormal ploidy (aneuploidy or tetraploidy) was identified frequently in adenomas and occasionally in hyperplasias with the exception that multiple endocrine neoplasia (MEN) biopsy specimens were uniformly diploid. DI for adenomas was similar to that for hyperplasias, and DI of both was higher than for normal glands. ICM-DI correlated positively with flow cytometry-DI and patient age and inversely with serum parathyroid hormone. PI was relatively low in all groups but was higher for hyperplasias versus normal parathyroids from patients with solitary adenomas and MEN versus non-MEN. PI correlated inversely with patient age.

CONCLUSIONS

DI by ICM differentiates normal from abnormal parathyroids. DI might influence extent of resection in two- and three-gland hyperplasia and selection of the most appropriate gland for autografting and cryopreservation in patients with four-gland hyperplasia.

Abnormality of the contralateral ligament after injuries of the medial collateral ligament. An experimental study in rabbits

The right medial collateral ligament of ninety-four adult, female rabbits was transected operatively. At three, six, fourteen, or forty weeks after the operation, the uninjured, contralateral (left) medial collateral ligaments of seventy-eight of the animals were tested biomechanically and compared with the left medial collateral ligaments of thirty-three normal female rabbits. The diameters of the mid-substance collagen fibrils in the medial collateral ligaments were also measured in the uninjured, contralateral hindlimbs of four animals at each interval and compared with the fibril diameters in three normal animals at each of three corresponding intervals. Subtle but significant differences between the uninjured, contralateral and the normal medial collateral ligaments with regard to biomechanical properties of collagen fibril diameters were found at all time-intervals. These results support the notion of a significant effect on the contralateral ligament after an injury to the medial collateral ligament and suggest that contralateral ligaments cannot be considered as a normal control group even in this relatively benign model of knee injury.

Ligament tension affects nuclear shape in situ: an in vitro study

This study was carried out to test the hypothesis that a relationship exists between ligament tension and ligament cell geometry. Rabbit knee joints were positioned at 70 degrees of joint flexion and the medial collateral ligament (MCL) was mechanically isolated and the femur-MCL-tibia complex was stretched or compressed by displacing the crosshead of a materials testing machine: -2.0 mm (relative compression), 0.0 mm (a reproducible no-load starting point), +/-0.7 mm or + 1.4 mm (relative tension). Each MCL complex was then fixed immediately in 10% neutral buffered formalin. Contralateral knees were dissected similarly with MCLs exposed and fixed in situ at 70 degrees of flexion. Subsequent to histological processing, measurements were made of the profiles of fibrocyte nuclei (since previous work has shown that nuclear shape closely approximates fibrocyte shape) that were located in the central portion of each MCL midsubstance using a video-based computerized morphometry system. Results showed that the dimensions of nuclei in the midsubstance of experimental MCLs were significantly longer and thinner at crosshead displacements that corresponded to increased ligament tension. At +1.4 mm of displacement fibrocyte nuclei were approximately 4 microm longer and 1 microm thinner than those fixed at 0.0 mm, an observation supported by a statistically significant increase in the mean maximum-to-minimum-diameter ratio and a significant decrease in mean cell roundness. These results strongly suggest that mechanical load can directly affect ligament fibrocyte geometry in situ. If a similar phenomenon also occurs in vivo, the metabolism of ligament fibrocytes may be influenced considerably by their loading history.

No effect of mop-ending on ligament healing. Rabbit studies of severed collateral knee ligaments

We have tested the hypothesis that increasing the surface area of cut ligament ends by the creation of "mop-ends" may alter the mechanical properties of healing medial collateral ligaments. In one group of New Zealand white rabbits, a 4-mm midsubstance segment was removed from the right ligament creating a gap (sharp cut-end healing group). In the other group, a similar gap was created but, in addition, cut ligament ends were split longitudinally across the width of the ligament creating "mop-ends", roughly tripling the total injury surface area. In all animals, the contralateral (left) leg was not operated on and served as an internal control. At least 8 animals from each injury model were killed at 3, 6, 14, and 40 weeks post-operatively. Both histological and mechanical tests showed that sharp-cut and mop-end injuries healed at similar rates with similar material.

Water content alters viscoelastic behaviour of the normal adolescent rabbit medial collateral ligament

Testing environment is an important factor in the outcome of mechanical tests on connective tissue. The purpose of this investigation was to determine the effect of ligament water content on ligament mechanical behaviour by altering the test environment. Water content of medial collateral ligament (MCLs) from 19 three-month-old New Zealand White rabbits was varied in subsets of ligaments pairs by means of immersion in 2, 10 or 25% sucrose or 0.9% phosphate-buffered saline (PBS) solutions for 1 h. One knee joint was cycled 50 times in the designated solution (experimental), while the contralateral knee (uncycled control) was simultaneously soaked in the same tank. Following cycling, the water contents of both test and control ligaments were determined. Water contents of 22 normal MCLs were determined immediately post-sacrifice and served as 'normal water content' controls. Normalized peak cyclic load changes were used as a measure of the viscoelastic behaviour of each MCL. Results demonstrated that only ligaments soaked (but not cycled) in a 10% sucrose solution had water contents (60.5 +/- 2.5%) which were statistically similar to the 22 fresh normal MCLs (63.9 +/- 6.0%). Ligaments soaked in PBS (74.0 +/- 1.3%) or 2% sucrose (69.2 +/- 2.3%) had significantly higher water contents compared to fresh normal MCLs. Ligaments with higher water contents (e.g. soaked in PBS or 2% sucrose) demonstrated greater cyclic load relaxation compared to ligaments with lower contents (e.g. soaked in 25 or 10% sucrose). Different fluid test environments can significantly alter ligament water content and, in turn, significantly affect ligament viscoelastic behaviour.

New dysmorphic syndrome with choanal atresia in siblings

We report five children from three families who presented with bilateral choanal atresia associated with a spectrum of additional malformations including cardiac defects, deafness, defects of the external ear, eyes and eye lids and a characteristic dysmorphic appearance. The children were of normal intelligence. This syndrome is distinct from CHARGE association.

Necrobacillosis with pancytopenia

Two young children whose presentation with necrobacillosis caused considerable diagnostic difficulty resulting in referral to an oncology unit are described. In both cases their severe suppurative multisystem illness was complicated by pancytopenia. One had bone marrow infarcts and severe endocarditis in addition to pulmonary involvement and the other had osteitis which resulted in a deformed humerus.

Collagen fibril diameters in the healing adult rabbit medial collateral ligament

This study was carried out to test the hypothesis that improvements in ligament scar mechanical behavior during healing may be related, in part, to increases in collagen fibril diameters. Forty-eight adult female New Zealand White rabbits had standardized midsubstance gap injuries created in their right medial collateral ligaments (MCLs) and were allowed normal cage activity until sacrifice in groups of 12 at 3, 6, 14 or 40 weeks post-injury. Eight animals in each group had both MCLs tested biomechanically while 4 animals had transmission EM investigation of midsubstance collagen fibril diameters by a standardized protocol. Results of mechanical tests showed a three- to fourfold increase in scar strength and stiffness over the intervals of healing studied while there was no change in collagen mean fibril minimum diameters. These results demonstrate no correlation between material or structural properties of scar and collagen fibril diameters in this model of healing and suggest that other mechanisms for scar mechanical improvement under these conditions must be investigated.

Lumbar nerve root compression and interstitial cystitis--response to decompressive surgery

An identifiable lumbar nerve root compression appears to cause urological dysfunction consistent with interstitial cystitis. Ten patients (9 females, 1 male) were evaluated for chronic pelvic pain. Cystoscopic and histological appearances were consistent with a diagnosis of interstitial cystitis. Magnetic resonance studies of the lower spine consistently demonstrated a lateral compression of the L5 dorsal nerve root. Decompression of the lateral foramina of L5 resulted in immediate relief of pain in 9 patients, who have been followed up for 6 months without a recurrence. Possible mechanisms involving sympathetic dystrophy of the pelvic plexus are reviewed.

A quantitative analysis of matrix alignment in ligament scars: a comparison of movement versus immobilization in an immature rabbit model

This investigation quantified the alignment of fibrillar matrix in normal rabbit medial collateral ligaments (MCLs) and in healing MCLs from animals treated with or without knee immobilization. Twenty-four immature female rabbits were given complete midsubstance injuries to their right MCLs. Fifteen of them had that knee pin immobilized in flexion, while the remaining nine were allowed unrestricted cage activity. Animals were sacrificed in groups of three at intervals of 3, 6, or 14 weeks after injury, and both healing MCLs and unoperated contralateral controls were fixed in situ for subsequent removal, freeze-fracture, and preparation for scanning electron microscopy (SEM). A random sampling of SEM photographs followed by automated, statistically validated image processing was used to quantify alignment of matrix in all samples. Results showed that nonimmobilized MCL scars in this model do remodel over 14 weeks of healing, returning to normal alignment values in that time. Surprisingly, MCL scars in immobilized knees were even better, with mean matrix alignments falling statistically within normal MCL limits at all healing intervals studied. If not due to an unknown sampling or fixation artifact, these results suggest that gross knee flexion and extension is not a prerequisite for scar matrix alignment in this immature model of ligament healing.

The effects of initial end contact on medial collateral ligament healing: a morphological and biomechanical study in a rabbit model

In this investigation, the effect of initial end contact on medial collateral ligament (MCL) healing was studied in the rabbit model. Sixty-eight 1-year-old New Zealand white rabbits were separated into two groups. In one group, a 4 mm saggital Z-plasty was performed in the right MCL midsubstance (contact group), and in the other group, an analogous 4 mm midsubstance segment was removed (gap group). Left knees were unoperated to serve as internal contralateral MCL controls. Animals had unrestricted cage activity until sacrifice in groups of eight at 3, 6, 14, and 40 weeks postoperatively. Early results demonstrated that contact and gap injuries healed with what appeared to be scar tissue both morphologically and biomechanically. In both groups, laxities recovered to their contralateral values within 6 weeks and biomechanical viscoelastic behaviors recovered to 68-92% of contralaterals by 14-40 weeks. Despite these similarities, contacts showed morphological and biomechanical evidence of improved healing over gaps. Contact scars remodeled more quickly, recovered laxity more quickly, and were generally closer to contralaterals than gaps in terms of their structural strength, stiffness, and material behaviors, after 40 weeks of healing. With the exception of appearances and failure stress, all measured properties of contact healing MCLs were statistically indistinguishable from contralateral MCLs at 40 weeks of healing. These advantages of contact healing in this model support speculations that there are differences in the early rate and possibly in the later quality of ligament healing when cut rabbit MCL ends are in proximity. Longer-term studies to define end points and mechanisms of healing are required.

Psychophysical evidence for an extrastriate contribution to a pattern-selective motion aftereffect

A stationary vertical test grating appears to drift to the left after adaptation to an inducing grating drifting to the right, this being known as the motion aftereffect (MAE). Pattern-specific motion aftereffects (PSMAEs) induced by superimposed pairs of gratings in which the component gratings drift up and down but the observer sees a single coherent plaid drifting to the right have been investigated. Two experiments are reported in which it is demonstrated that the PSMAE is tuned more to the motion of the pattern than to the orientation and direction of motion of the component gratings. However, when subjects adapt to the component gratings in alternation, aftereffect magnitude is dependent upon the individual grating orientations and motion directions. These results can be interpreted in terms of extrastriate contributions to the PSMAE, possibly arising from the middle temporal area, where some cells, unlike those in striate cortex (V1), are tuned to pattern motion rather than to component motion.

4-Hydroxynonenal: a specific indicator for canine neuronal-retinal ceroidosis

Previous attempts to demonstrate abnormalities in lipid peroxidation in various forms of the neuronal ceroid-lipofuscinoses (NCL) have been unrewarding up to and including the peroxide level (peroxidase). In this experiment a survey was made in a canine model of NCL to study the relative concentration of 4-hydroxynonenal (HNE), a fragment derived from an acute oxidation product of unsaturated fatty acids. Peripheral blood cells and various tissues from an affected and a normal control dog were surveyed. HNE was assayed after reacting with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine to form the 4-hydroxynonenal (O-pentafluorobenzyl) oxime. This reaction product was then separated by capillary gas liquid chromatography (g/c) and quantitated by flame ionization. The survey showed that neutrophils isolated from affected dogs and carriers contained abnormal amounts of HNE when compared with normal control animals. Two carriers had mean values of +3,289% above normal, and neutrophils from two affected animals were +4,873% above normal. In addition, an examination of the relative HNE levels in brain, retina, retinal pigment epithelium (RPE), and kidney of an affected dog compared with a control animal also showed abnormal levels of HNE, particularly in brain (+168%) and in the RPE (+135%), the two organs exhibiting the most severe pathologic damage unique to these disorders. These findings, although preliminary, clearly document a role for HNE in this canine form of human NCLs. The well-known cytotoxic properties of HNE and other alpha,beta unsaturated aldehydes suggest a primary role in the pathogenetic events of this disorder.

Isolation and characterization of Pseudomonas putida R-prime plasmids

A number of enhanced chromosome mobilizing (ECM) plasmids derived from the wide host range plasmid R68 have been used to construct R-prime plasmids carrying a maximum of two map minutes of the Pseudomonas putida PPN chromosome, using Pseudomonas aeruginosa PAO as the recipient. For one ECM plasmid, pMO61, the ability to form R-primes did not correlate with the ability to mobilize chromosomes in intrastrain crosses, suggesting that different mechanisms are involved. Physical analysis of one R-prime showed that 3.5 kb of chromosomal DNA had been inserted between the tandem IS21 sequences carried by the parent ECM plasmid.

Studies on the mechanism of human natural killer cell-mediated cytolysis. I. Modulation by dexamethasone and arachidonic acid

Natural killer (NK) cell-mediated cytotoxicity, as measured by the lysis of the human erythroleukemic cell line K562, is inhibited by the glucocorticosteroid dexamethasone (DEX). Kinetic analysis revealed that DEX inhibits an early event(s) in the lytic mechanism and that the inhibition is both transient and readily reversible if DEX is removed. The inhibition is not due to the production of a DEX-induced inhibitory protein or decreased target-cell binding. Attempts to counter the effects of DEX through the addition of inducers of NK activity were unsuccessful. Neither the calcium ionophore A23187 nor exogenous cyclic GMP was able to reverse the inhibition by DEX. The addition of arachidonic acid (AA), a pharmacologically active metabolite of phospholipase A-2 activation, was also unsuccessful in reversing the effects of DEX. In fact, AA itself inhibited NK activity in a dose-dependent fashion. This inhibition was not due to reduced target binding and was observed even in the presence of indomethacin. It is concluded that DEX blocks an early membrane-signaling event necessary to activate the lytic mechanism and that inhibition was not through some alternative mechanism. Inhibition of NK activity by arachidonic acid is not yet understood but most likely is not a result of enhanced prostaglandin synthesis. Hence, the study of DEX and AA inhibition provides a new approach to unravel some of the intricacies surrounding NK-mediated tumor target destruction.