Civilian Ballistic Injuries to the Atlantoaxial Spine: A Single Institution Case Series

STUDY DESIGN

Retrospective case series.

OBJECTIVE

Describe the injury characteristics of ballistic fractures involving the atlantoaxial spine.

SUMMARY OF BACKGROUND DATA

Civilian gunshot wounds to the spine are an increasingly common injury in the United States. Civilian studies have focused on ballistic injuries to the entire spine as opposed to a region-specific fashion. Only a single 10-patient case series investigating ballistic fractures to the upper cervical spine (C1 and C2) exists, leaving a large gap in the understanding of this injury complex.

METHODS

A retrospective chart review was performed. Extracted data included patient demographics, neurological status on presentation, fracture morphology, assessment of stability, other associated injuries, and surgical procedures performed. Proportional analysis was performed to characterize the fractures and their associated neurological injuries.

RESULTS

Thirty-six patients were identified, with 86% being male with an average patient age of 30.0 ± 10.36 years (mean ± SD). Fracture morphology was characterized using proportional analysis. Initial neurological exams were either ASIA A or ASIA E, without any incomplete injuries noted. Patients who sustained a transcanal injury did not show any neurological improvement. The initial in-hospital mortality rate was 5.6%, with a 1-year mortality rate of 8.3%. There is a high incidence of associated vascular injury (66%) and mandible fracture (33%).

CONCLUSIONS

Ballistic penetrating trauma to the atlantoaxial spine often results in complex injury patterns necessitating multidisciplinary care with high rates of morbidity and mortality. If neurological deficits are present initially, they are often complete. Two thirds of patients sustained an associated vascular injury, which should be screened for with CT angiography.

Racial Disparities in the Operative Management of Orthopedic Trauma: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this study was to investigate if race is associated with the likelihood of operative management of acute fractures.

METHODS

A systematic review of the literature was performed using the PubMed, EMBASE, and Cochrane databases to identify studies associated with social disparities and acute orthopedic trauma. Peer-reviewed studies commenting on social disparities and the decision to pursue operative or non-operative management of acute fractures were identified for detailed review. Study characteristics and odds ratios were extracted from each article. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed. A quality analysis of the data was also performed.

RESULTS

In total, 13 studies were identified and 8 were included in the meta-analysis totaling 743,846 fractures. Hip, distal radius, pelvic, tibial plateau, clavicle, femoral neck, and femoral shaft fractures were represented in this patient population. The meta-analysis demonstrated that White race is associated with a higher likelihood of operative intervention compared to all other races pooled together (odds ratio, 1.31; 95% confidence interval 1.16 to 1.47; p < .0001) as well as Black race (odds ratio 1.39; 95% confidence interval 1.12 to 1.72; p = .0025).

CONCLUSIONS

Non-White race and Black race are associated with a lower likelihood of receiving surgical management of acute orthopedic trauma. Surgeons and health systems should be aware of these inequities and consider strategies to mitigate bias and ensure all patients receive appropriate and timely care regardless of race.

Integrin-specific hydrogels modulate transplanted human bone marrow-derived mesenchymal stem cell survival, engraftment, and reparative activities

Stem cell therapies are limited by poor cell survival and engraftment. A hurdle to the use of materials for cell delivery is the lack of understanding of material properties that govern transplanted stem cell functionality. Here, we show that synthetic hydrogels presenting integrin-specific peptides enhance the survival, persistence, and osteo-reparative functions of human bone marrow-derived mesenchymal stem cells (hMSCs) transplanted in murine bone defects. Integrin-specific hydrogels regulate hMSC adhesion, paracrine signaling, and osteoblastic differentiation in vitro. Hydrogels presenting GFOGER, a peptide targeting α2β1 integrin, prolong hMSC survival and engraftment in a segmental bone defect and result in improved bone repair compared to other peptides. Integrin-specific hydrogels have diverse pleiotropic effects on hMSC reparative activities, modulating in vitro cytokine secretion and in vivo gene expression for effectors associated with inflammation, vascularization, and bone formation. These results demonstrate that integrin-specific hydrogels improve tissue healing by directing hMSC survival, engraftment, and reparative activities.

Bacteriophage delivering hydrogels reduce biofilm formation in vitro and infection in vivo

Implanted orthopedic devices become infected more frequently than any other implanted surgical device. These infections can be extremely costly and result in significant patient morbidity. Current treatment options typically involve the long term, systemic administration of a combination of antibiotics, often followed by implant removal. Here we engineered an injectable hydrogel capable of encapsulating Pseudomonas aeruginosa bacteriophage and delivering active phage to the site of bone infections. Bacteriophage retain their bacteriolytic activity after encapsulation and release from the hydrogel, and their rate of release from the hydrogel can be controlled by gel formulation. Bacteriophage-encapsulating hydrogels effectively kill their host bacteria in both planktonic and biofilm phenotypes in vitro without influencing the metabolic activity of human mesenchymal stromal cells. Bacteriophage-encapsulating hydrogels were used to treat murine radial segmental defects infected with P. aeruginosa. The hydrogels achieved a 4.7-fold reduction in live P. aeruginosa counts at the infection site compared to bacteriophage-free hydrogels at 7 days postimplantation. These results support the development of bacteriophage-delivering hydrogels to treat local bone infections.

Lysostaphin and BMP-2 co-delivery reduces S. aureus infection and regenerates critical-sized segmental bone defects

Staphylococcus aureus is the most common pathogen associated with bacterial infections in orthopedic procedures. Infections often lead to implant failure and subsequent removal, motivating the development of bifunctional materials that both promote repair and prevent failure due to infection. Lysostaphin is an anti-staphylococcal enzyme resulting in bacterial lysis and biofilm reduction. Lysostaphin use is limited by the lack of effective delivery methods to provide sustained, high doses of enzyme to infection sites. We engineered a BMP-2-loaded lysostaphin-delivering hydrogel that simultaneously prevents S. aureus infection and repairs nonhealing segmental bone defects in the murine radius. Lysostaphin-delivering hydrogels eradicated S. aureus infection and resulted in mechanically competent bone. Cytokine and immune cell profiling demonstrated that lysostaphin-delivering hydrogels restored the local inflammatory environment to that of a sterile injury. These results show that BMP-2-loaded lysostaphin-delivering hydrogel therapy effectively eliminates S. aureus infection while simultaneously regenerating functional bone resulting in defect healing.

Image-Guided Transarterial Directed Delivery of Human Mesenchymal Stem Cells for Targeted Gastrointestinal Therapies in a Swine Model

PURPOSE

To evaluate the feasibility of catheter-directed intra-arterial stem cell delivery of human mesenchymal stem cells (MSCs) to the small bowel in a porcine model.

MATERIALS AND METHODS

The cranial mesenteric artery of 6 Yucatan minipigs was selectively catheterized under fluoroscopic guidance following cut-down and carotid artery access. A proximal jejunal branch artery was selectively catheterized for directed delivery of embolic microspheres (100-300 μm) or MSCs (0.1-10 million cells). The pigs were euthanized after 4 hours and specimens collected from the proximal duodenum and the targeted segment of the jejunum. The Chiu/Park system for scoring intestinal ischemia was used to compare hematoxylin and eosin-stained sections of jejunum and duodenum.

RESULTS

Successful delivery of microspheres or MSCs in a proximal jejunal branch artery of the cranial mesenteric artery was achieved in all subjects. Radiopaque microspheres and post-delivery angiographic evidence of stasis in the targeted vessels were observed on fluoroscopy after delivery of embolics. Preserved blood flow was observed after MSC delivery in the targeted vessel. The Chiu/Park score for intestinal ischemia in the targeted proximal jejunal segments were similar for microspheres (4, 4; n = 2) and MSCs (4, 4, 4, 3; n = 4), indicating moderate ischemic effects that were greater than for control duodenal tissue (3, 1; 0, 0, 3, 3).

CONCLUSIONS

Selective arteriographic deployment of MSCs in swine is feasible for study of directed intestinal stem cell delivery. In this study, directed therapy resulted in intestinal ischemia.

Local immunomodulation Fas ligand-engineered biomaterials achieves allogeneic islet graft acceptance

Islet transplantation is a promising therapy for type 1 diabetes. However, chronic immunosuppression to control rejection of allogeneic islets induces morbidities and impairs islet function. T effector cells are responsible for islet allograft rejection and express Fas death receptors following activation, becoming sensitive to Fas-mediated apoptosis. Here, we report that localized immunomodulation using microgels presenting an apoptotic form of the Fas ligand with streptavidin (SA-FasL) results in prolonged survival of allogeneic islet grafts in diabetic mice. A short course of rapamycin treatment boosted the immunomodulatory efficacy of SA-FasL microgels, resulting in acceptance and function of allografts over 200 days. Survivors generated normal systemic responses to donor antigens, implying immune privilege of the graft, and had increased CD4⁺CD25⁺FoxP3⁺ T regulatory cells in the graft and draining lymph nodes. Deletion of T regulatory cells resulted in acute rejection of established islet allografts. This localized immunomodulatory biomaterial-enabled approach may provide an alternative to chronic immunosuppression for clinical islet transplantation.

Inhibition of Bacterial Adhesion on Nanotextured Stainless Steel 316L by Electrochemical Etching

Bacterial adhesion to stainless steel 316L (SS316L), which is an alloy typically used in many medical devices and food processing equipment, can cause serious infections along with substantial healthcare costs. This work demonstrates that nanotextured SS316L surfaces produced by electrochemical etching effectively inhibit bacterial adhesion of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, but exhibit cytocompatibility and no toxicity toward mammalian cells in vitro. Additionally, the electrochemical surface modification on SS316L results in formation of superior passive layer at the surface, improving corrosion resistance. The nanotextured SS316L offers significant potential for medical applications based on the surface structure-induced reduction of bacterial adhesion without use of antibiotic or chemical modifications while providing cytocompatibility and corrosion resistance in physiological conditions.

Evaluation of Hydrogels Presenting Extracellular Matrix-Derived Adhesion Peptides and Encapsulating Cardiac Progenitor Cells for Cardiac Repair

Cell therapy is an emerging paradigm for the treatment of heart disease. In spite of the exciting and promising preclinical results, the benefits of cell therapy for cardiac repair in patients have been modest at best. Biomaterials-based approaches may overcome the barriers of poor differentiation and retention of transplanted cells. In this study, we prepared and tested hydrogels presenting extracellular matrix (ECM)-derived adhesion peptides as delivery vehicles for c-kit⁺ cardiac progenitor cells (CPCs). We assessed their effects on cell behavior in vitro as well as cardiac repair in rats undergoing ischemia reperfusion. Hydrogels presenting the collagen-derived GFOGER peptide induced cardiomyocyte differentiation of CPCs as demonstrated by increased expression of cardiomyocyte structural proteins. However, conditioned media obtained from GFOGER hydrogels showed lower levels of secreted reparative factors. Interestingly, following injection in rats undergoing ischemia-reperfusion, treatment with CPCs encapsulated in nonadhesive RDG-presenting hydrogels resulted in the preservation of cardiac contractility and attenuation of postinfarct remodeling whereas the adhesion peptide-presenting hydrogels did not induce any functional improvement. Retention of cells was significantly higher when delivered with nonadhesive hydrogels compared to ECM-derived peptide gels. These data suggest that factors including cell differentiation state, paracrine factors and interaction with biomaterials influence the effectiveness of biomaterials-based cell therapy. A holistic consideration of these multiple variables should be included in cell-biomaterial combination therapy designs.

Vasculogenic hydrogel enhances islet survival, engraftment, and function in leading extrahepatic sites

Islet transplantation is a promising alternative therapy for insulin-dependent patients, with the potential to eliminate life-threatening hypoglycemic episodes and secondary complications of long-term diabetes. However, widespread application of this therapy has been limited by inadequate graft function and longevity, in part due to the loss of up to 60% of the graft in the hostile intrahepatic transplant site. We report a proteolytically degradable synthetic hydrogel, functionalized with vasculogenic factors for localized delivery, engineered to deliver islet grafts to extrahepatic transplant sites via in situ gelation under physiological conditions. Hydrogels induced differences in vascularization and innate immune responses among subcutaneous, small bowel mesentery, and epididymal fat pad transplant sites with improved vascularization and reduced inflammation at the epididymal fat pad site. This biomaterial-based strategy improved the survival, engraftment, and function of a single pancreatic donor islet mass graft compared to the current clinical intraportal delivery technique. This biomaterial strategy has the potential to improve clinical outcomes in islet autotransplantation after pancreatectomy and reduce the burden on donor organ availability by maximizing graft survival in clinical islet transplantation for type 1 diabetes patients.

Synthetic matrices reveal contributions of ECM biophysical and biochemical properties to epithelial morphogenesis

Epithelial cells cultured within collagen and laminin gels proliferate to form hollow and polarized spherical structures, recapitulating the formation of a rudimentary epithelial organ. However, the contributions of extracellular matrix (ECM) biochemical and biophysical properties to morphogenesis are poorly understood because of uncontrolled presentation of multiple adhesive ligands, limited control over mechanical properties, and lot-to-lot compositional variability in these natural ECMs. We engineered synthetic ECM-mimetic hydrogels with independent control over adhesive ligand density, mechanical properties, and proteolytic degradation to study the impact of ECM properties on epithelial morphogenesis. Normal cyst growth, polarization, and lumen formation were restricted to a narrow range of ECM elasticity, whereas abnormal morphogenesis was observed at lower and higher elastic moduli. Adhesive ligand density dramatically regulated apicobasal polarity and lumenogenesis independently of cell proliferation. Finally, a threshold level of ECM protease degradability was required for apicobasal polarity and lumen formation. This synthetic ECM technology provides new insights into how cells transduce ECM properties into complex morphogenetic behaviors.

Carotid artery intima-media thickness and the renin-angiotensin system

Carotid artery intima-media thickness (IMT) is a biomarker for cardiovascular disease that also predicts the risk of cardiovascular mortality. Angiotensin-converting enzyme (ACE) inhibition is a unique therapeutic modality because it both treats hypertension and improves arterial health and cardiovascular disease outcomes. Controversy exists regarding the role of ACE inhibitors and angiotensin receptor blockers (ARBs) in IMT regression. Our article provides an update on how ACE inhibitors and ARBs could play a role in decreasing IMT.

Successful external cardioversion of atrial fibrillation in patients referred to an electrophysiologist for internal cardioversion

BACKGROUND

Internal cardioversion of atrial fibrillation with direct current energy has become an increasingly employed technique for patients who fail external cardioversion.

HYPOTHESIS

The purpose of this study was to determine whether internal cardioversion could be avoided by careful attention to cardioversion technique in a group of patients referred specifically for internal cardioversion after failed external cardioversion by community cardiologists.

METHODS

We performed external cardioversion utilizing two operators applying significant pressure to the thorax with up to 360 J prior to the planned internal cardioversion in 20 patients referred for internal cardioversion after failed attempts at external cardioversion.

RESULTS

Sixteen patients (80%) were successfully cardioverted and avoided the risk, inconvenience, and cost of internal cardioversion.

CONCLUSION

External cardioversion with significant anterior paddle pressure by two operators can decrease the need for internal cardioversion in a significant portion of patients referred to electrophysiologists for internal cardioversion and should be considered prior to an invasive procedure.

Complementary and alternative medicine in obstetrics

OBJECTIVE

To identify, survey and review randomized controlled studies of the use of complementary and alternative medicine (CAM) for obstetric treatment or health promotion.

METHODS

The MEDLINE database was searched to identify randomized controlled trials of CAM treatment and therapies in obstetrics. Studies examining modalities for treatment or improvement of health status were reviewed.

RESULTS

Fifty-four articles assessing a variety of health modalities met the criteria for inclusion. Acupressure and ginger for prenatal nausea and vomiting, moxibustion for version of breech presentation, sterile water injections for back pain relief in labor, and perineal massage to prevent perineal trauma have three or more studies demonstrating beneficial effect. Other interventions have been studied less, and evidence for them is limited.

CONCLUSIONS

Some CAM interventions have evidence of effectiveness for use in obstetric patients, while others require further investigation before they can be considered for use in practice.

Relaxation therapy for insomnia: nighttime and day time effects

We compared day time functioning in college students with and without insomnia and explored changes in day time functioning after progressive relaxation (PR) treatment for insomnia. Students with insomnia (SWI; n = 57) were compared to a control group of students not complaining of insomnia (SNI; n = 61) on self-reported sleep variables and five questionnaires: Insomnia Impact Scale (IIS), Dysfunctional Beliefs and Attitudes About Sleep Scale (DBAS), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and Penn State Worry Questionnaire (PSWQ). SWI demonstrated significant impairment on all day time functioning and sleep measures compared to SNI. To investigate treatment effects on day time functioning, 28 SWI were randomly assigned to PR. Treated SWI were compared to untreated SWI and SNI at posttreatment. Treated participants improved sleep in comparison to untreated SWI, but failed to show significant improvements in day time functioning. Insomnia treatments focused on improving sleep may not improve day time functioning, or day time gains may emerge more slowly than sleep gains. This study documents the wide range of day time functioning complaints in young adults with insomnia and suggests that the goal of insomnia treatment should be to not only improve sleep but also to improve the subjective experience of day time functioning.

Psychological treatment of secondary insomnia

Psychological treatment of insomnia has focused on primary insomnia (i.e., having a psychological origin). Secondary insomnia, sleep disturbance caused by a psychiatric or medical disorder, although it is more common than primary insomnia, has received very little attention as a result of the belief that it would be refractory to treatment. The present study randomly assigned older adults with secondary insomnia to a treatment group, 4 sessions composed of relaxation and stimulus control, or a no-treatment control group. Self-report assessments conducted at pretreatment, posttreatment, and a 3-month follow-up revealed that treated participants showed significantly greater improvement on wake time during the night, sleep efficiency percentage, and sleep quality rating. The authors hypothesize that treatment success was probably due in part to difficulty in diagnostic discrimination between primary and secondary insomnia.

Atypical atrial flutter originating in the right atrial free wall

BACKGROUND

Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited.

METHODS AND RESULTS

In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial flutter, an additional atypical atrial flutter was mapped to the right atrial free wall. Five patients had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the remaining patient. High-density electroanatomic maps of the reentrant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypical atrial flutter in each patient. Atrial flutter has not recurred in any patient (follow-up, 18+/-17 months; range, 3 to 40 months).

CONCLUSIONS

Atrial flutter can arise in the right atrial free wall. This form of atypical atrial flutter could account for spontaneous or inducible atrial flutter observed in patients referred for ablation and is eliminated with linear ablation directed at the inferolateral right atrium.

Biofiltration of high loads of ethyl acetate in the presence of toluene

To date, biofilters have been used primarily to control dilute, usually odorous, off-gases with relatively low volatile organic compound (VOC) concentrations (< 1 g m-3) and VOC loads (< 50 g m-3 hr-1). Recently, however, U.S. industry has shown an interest in applying biofilters to higher concentrations of VOCs and hazardous air pollutants (HAPs). In this study, the behavior of biofilters under high loads of binary VOC mixtures was studied. Two bench-scale biofilters were operated using a commercially available medium and a mixture of wood chips and compost. Both were exposed to varying mixtures of ethyl acetate and toluene. Concentration profiles and the corresponding removal efficiencies as a function of VOC loading were determined through frequent grab-sampling and GC analysis. Biofilter response to two frequently encountered operating problems--media dry-out and operating temperatures exceeding 40 degrees C--was also evaluated under controlled conditions. Microbial populations were also monitored to confirm the presence of organisms capable of degrading both major off-gas constituents. The results demonstrated several characteristics of biofilters operating under high VOC load conditions. Maximum elimination capacities for ethyl acetate were typically in the range of 200 g m-3 hr-1. Despite the presence of toluene degraders, the removal of toluene was inhibited by high loads of ethyl acetate. Several byproducts, particularly ethanol, were formed. Short-term dry-out and temperature excursions resulted in reduced performance.

Daytime functioning in obstructive sleep apnea patients: exercise tolerance, subjective fatigue, and sleepiness

A sample of 32 obstructive sleep apnea patients (27 males, 5 females) was assessed with overnight polysomnography and the Multiple Sleep Latency Test (MSLT), an objective measure of daytime sleepiness. Patients also participated in a maximal exercise test, which served as an objective indicator of physical fatigue. The Fatigue Severity Scale (FSS) was used as a subjective measure of fatigue. Subjective fatigue ratings were significantly correlated with percent of predicted maximum heart rate achieved during exercise testing, suggesting that self-reported fatigue in apnea patients may refer to reduced physical fitness. FSS scores and exercise testing results were not significantly correlated with the MSLT, indicating that daytime fatigue and daytime sleepiness are independent problems in apnea patients. Participants self-reported a high level of fatigue, and exercise testing revealed decreased physical work capacity among apnea patients, but objective and subjective indicators of fatigue were not significantly correlated with apnea severity. A higher percentage of REM sleep predicted greater work capacity.

A left free-wall, decrementally conducting, atrioventricular (Mahaim) fiber: diagnosis at electrophysiological study and radiofrequency catheter ablation guided by direct recording of a Mahaim potential

A 64-year-old female with Wolff-Parkinson-White syndrome and an ECG demonstrating a right posterolateral accessory pathway was referred for electrophysiological study. During electrophysiological testing two AV pathways were identified: a right posterolateral pathway that displayed conventional electrophysiological properties: and a left free-wall pathway that conducted only anterogradely and demonstrated decremental properties. Two separate wide complex tachycardias were induced that utilized the left free-wall pathway anterogradely and either the AV node or the right posterolateral accessory pathway retrogradely. A discrete electrical potential on the free wall of the mitral annulus was identified during tachycardia and was utilized to facilitate mapping and ablation.

Indwelling pericardial drainage catheter break secondary to heart movement and catheter angulation

We report on a case of a pericardial drainage catheter that severed on attempted removal. Surgery was required to remove the retained portion. No manufacturing defects were found on analysis of the catheter. Shear forces due to heart movement and the angle of catheter entry into the pericardium were the suspected reasons for the catheter disruption.

Substance abuse, traumatic brain injury and neuropsychological outcome

The neuropsychological performance of 119 patients with severe closed traumatic brain injury (TBI) who had received toxicology screens at the time of trauma centre admission was examined. Three groups were created: normal screen, positive alcohol screen, or positive abused drugs screen (with or without the presence of alcohol). The admitting Glasgow Coma Scale (GCS) score was significantly lower in the positive alcohol screen group than the normal screen group, while the three groups did not differ in length of post-traumatic amnesia (PTA) or years of education. Neuropsychological assessment was conducted during inpatient rehabilitation, following resolution of PTA. Normal screen patients obtained significantly better scores than the abused-drugs patients on the Full Scale IQ (FIQ) and Verbal IQ (VIQ) indices of the Wechsler Adult Intelligence Scale-Revised and the Verbal Memory, General Memory, Attention-Concentration, and Delayed Recall indices of the Wechsler Memory Scale-Revised. Normal screen patients also scored significantly higher than positive alcohol screen patients on FIQ and VIQ indices and all five indices from the Wechsler Memory Scale-Revised. These data suggest the existence of an additive effect of substance abuse on neuropsychological outcome in TBI. Findings have potential implications for both acute management and rehabilitation of TBI.

Recognition memory test: validity in diffuse traumatic brain injury

This study evaluated the validity and clinical utility of the Recognition Memory Test (RMT) as a measure of memory in severe traumatic brain injury (TBI). RMT scores for 86 TBI inpatients were related to injury severity, lesion location, and other memory indices. Only recognition memory for words (RMW) was significantly (p<0 01) related to duration of posttraumatic amnesia and a measure of "day to day" memory. Both RMT subtests showed expected modality-specific relationships with other clinical memory tasks. Patients with normal CT and right sided CT lesions tended to be more frequently impaired on recognition memory for faces (RMF) than RMW.

The bovine placentome in bacterial and mycotic abortions

Placentomes were extracted from the uteri of 22 aborted cows and examined to detect the cause of abortion; fetuses or fetal abomasal contents from 15 of the cows were also examined. Firm diagnoses of Pasteurella haemolytica, Actinomyces pyogenes, Listeria monocytogenes, Bacillus licheniformis, Aspergillus fumigatus or Mortierella wolfii abortion were made in 11 cases. The histopathological lesions showed some correlation with the identity of the bacterium isolated; the lesions of mycotic abortion were distinct and characterised by a coagulative necrosis. The removal of a placentome was not followed by any observable deleterious effects.

Variable-interval probe test as a tool for repeated measurements of spatial memory in the water maze

Probe tests provide an important additional converging operation to identify the characteristics of cognitive processes being assessed by other behavioral measures. We introduce a new procedure using a variable-interval (VI) probe test to assess spatial memory in the water maze. Three groups of rats were trained in spatial discrimination with traditional platform trials. For the probe trials, 2 groups had no-platform (NP) probe trials in which the escape platform was unavailable for the entire trial. The 3rd group had variable interval (VI) probe trials, in which the escape platform was available only after a VI. The VI probe trial was a more sensitive measure of spatial memory than was the NP probe trial and was useful for repeated measurements of spatial memory, a characteristic not readily attainable with the NP probe trial.

Variable-interval probe test as a tool for repeated measurements of spatial memory in the water maze

Probe tests provide an important additional converging operation to identify the characteristics of cognitive processes being assessed by other behavioral measures. We introduce a new procedure using a variable-interval (VI) probe test to assess spatial memory in the water maze. Three groups of rats were trained in spatial discrimination with traditional platform trials. For the probe trials, 2 groups had no-platform (NP) probe trials in which the escape platform was unavailable for the entire trial. The 3rd group had variable interval (VI) probe trials, in which the escape platform was available only after a VI. The VI probe trial was a more sensitive measure of spatial memory than was the NP probe trial and was useful for repeated measurements of spatial memory, a characteristic not readily attainable with the NP probe trial.

The use of an antimicrobial and competitive exclusion combination in Salmonella-infected pullet flocks

Replacement pullets which had been found infected with Salmonella were treated with antibiotics for 12 days, moved to a clean house by the 11th day and given 2 treatments with a competitive exclusion (CE) preparation on the 13th and 15th day. It was found necessary to supply a small amount of feed to generate a thirst in the birds and ensure efficient and rapid consumption of the CE preparation. Salmonella could not be grown from the intestines or other organs of birds after this procedure had been carried out.

Purification of human liver aldehyde dehydrogenase by high-performance liquid chromatography and identification of isoenzymes by immunoblotting

Human liver aldehyde dehydrogenase (ALDH) exists in multiple molecular forms. Two different isoenzymes of ALDH have been purified which will oxidize acetaldehyde to acetate. ALDH1 is localized principally in hepatocyte cytosol and exhibits a Km for acetaldehyde of about 0.1 mM at pH 9.5. ALDH2 is mitochondrial in origin and exhibits low Km for acetaldehyde, about 1 microM. We have developed rapid purification procedures for ALDH1 and ALDH2 by use of agarose-AMP affinity chromatography and high-performance anion-exchange liquid chromatography (HPLC). The method takes less time and affords higher yields of the labile ALDH isoenzymes than conventional column chromatography methods. A previously uncharacterized ALDH form has been identified by anion-exchange HPLC which exhibits high Km for acetaldehyde, about 1 mM, and is very labile. Polyclonal antibodies to the purified ALDH1 and ALDH2 isoenzymes have been prepared. As evidenced by immunoblotting of starch gels containing the purified isoenzymes, anti-ALDH1 does not crossreact with ALDH2 and anti-ALDH2 does not crossreact with ALDH1. The anti-ALDH2 antibody identifies the "inactive" variant of ALDH2 in Japanese livers exhibiting the "deficient" ALDH2 phenotype. The sensitivity of detection of ALDH isoenzymes in liver homogenate-supernatants by immunoblotting of starch gels is about 10-fold greater than that by activity staining.

Disruption of learned and spontaneous alternation in the rat by trimethyltin: chronic effects

Trimethyltin (TMT) is a known neurotoxin which produces behavioral anomalies including hyperactivity, aggressiveness, perseveration, and learning deficits. These dysfunctions appear to be related to a severe loss of neurons in the hippocampal formation of the TMT-treated rat. In order to assess the effect of TMT exposure upon spontaneous and learned alternation, male Long-Evans rats were pretested for reinforced spontaneous alternation and then treated with either 7 mg/kg of TMT [( CH3]3SnCl) or the 0.9% NaCl vehicle. After treatment these groups were further subdivided and half of each group was tested in a "T" maze for reinforced spontaneous alternation while the remainder was tested for learned alternation. The TMT-treated rats uniformly ran faster on the second choice of reinforced spontaneous alternation tests than did controls. In addition, the TMT-treated rats made fewer alternations than controls, regardless of whether or not only successful alternations were being reinforced. These results are discussed in light of the known neurobehavioral consequences of TMT exposure.

Alterations in regulatory and locomotor behaviors following trimethyltin exposure in the rat: a time and dose analysis

Adult male hooded rats were tested pretreatment for spontaneous alternation and open-field behaviors. Animals were then intubated with either 5 or 7 mg/kg trimethyltin chloride (TMT Cl) or the isotonic saline vehicle. Post-treatment, animals were again tested for spontaneous alternation and open-field behaviors during three separate 5-day periods: days 14-18, days 56-60 and days 106-110. Additionally, both body weight and water intake were assessed. The larger dose of TMT Cl resulted in significant, but temporary reduction in body weight, elevated water intake for approximately 3 weeks, and a persistent increase in open-field activity. The smaller dose of TMT Cl resulted in elevated water intake for approximately 3 weeks and a temporary increase in open-field activity. Since the tendency to enter choice arms decreased in all groups across testing sessions, the effects of TMT Cl on spontaneous alternation could not be accurately assessed.

Endocrine and ovarian changes in dairy cattle fed a low beta-carotene diet during an oestrus synchronisation regime

Twelve Friesian cows, 76 to 110 days calved, with blood cell counts and Compton metabolic profile values in the normal range throughout, were housed and fed a marginal diet for varying periods before being injected twice, 11 days apart, with cloprostenol. Artificial insemination was carried out 72 and 96 hours after the second injection. Plasma concentrations of progesterone, oestradiol 17 beta, luteinising hormone, follicle stimulating hormone, and beta-carotene were monitored during this regime as were uterine and ovarian changes. Progesterone profiles were followed for a further 21 days by assay of milk samples. Subsequent rectal examinations showed that five of the 12 cows conceived at controlled oestrus and another four within 52 days of this time. No correlation was observed between time of conception and condition score, metabolic profiles or haematological parameters; there was a correlation between time of conception and plasma beta-carotene concentrations and cows with lower beta-carotene values showed cyclic irregularities or appeared to have depressed steroid hormone production.

Depressed excitability and integrated EEGs following hippocampal afterdischarges

Rats with chronic hippocampal electrode implants had afterdischarges induced with electrical stimulus intensities of 115, 200, and 800% of a previously determined threshold. Afterdischarge duration, postictal EEG depression duration, and the duration of postictal electrical hypoexcitability were assessed. After discharge duration varied inversely with stimulus intensity as did the duration of postictal hypoexcitability. However, the duration of postictal EEG depression increased with stimulus intensity. This dissociation between postictal neuroexcitability and EEG depression is discussed in terms of possible underlying cholinergic mechanisms.

Influence of stage of oestrous cycle on time of oestrus

The first of 2 injections of 0.5 mg cloprostenol (PG1 and PG2) eleven days apart was given to 19 Friesian-Hereford cross heifers between days 8-14 of their cycle (Treatment A) and 16 similar animals between days 0-4 (Treatment B). Oestrus show was monitored by Kamar Heat Mount detectors and vasectomised bulls with chin-ball markers. Blood samples taken at PG1, six days later, at PG2 and four days later were assayed for progesterone to confirm that luteolysis had occurred as expected. Four hourly rectal examinations of the ovaries were carried out from 56-112 hours after PG2 and four hourly blood samples from 36-96 hours after PG2 were collected for FSH and LH assay. Mean time in hours from PG2 to oestrus onset, LH peak and ovulation respectively was 57.4 +/- 2.9, 60.2 +/- 2.0, 91.7 +/- 1.8 for Treatment A and 64.9 +/- 4.1, 68.9 +/- 2.4, 96.7 +/- 1.3 for Treatment B. Treatment A animals showed significantly higher (p<0.01) FSH levels at PG2 than Treatment B. Time from PG2 to LH peak was significantly shorter in animals treated either on days 7 and 8 (p<0.01) or days 15-16 (p<0.05) of their cycle compared with treatment on days 12-14 and it is suggested that these shorter response times correspond to an early and late cycle wave of follicular growth. Secondary FSH peaks some 28 hours after that occurring synchronously with the pre-ovulatory LH peak were observed to be significantly (p<0.01) higher at oestrus associated with the early cycle follicular growth wave as compared with that later in the cycle which may argue a difference in endocrine control of the two periods of follicular maturation.