Evaluation of dietary and management risk factors for enterolithiasis among horses in California.

Enteroliths are intestinal calculi that result in intestinal obstruction and colic in horses. Equine enterolithiasis occurs worldwide, but the disease is particularly prevalent in some geographic locations, including California. The objectives of this study were to evaluate dietary and environmental risk factors for the disease. This was accomplished through a case-control study by comparing horses with colic from enterolithiasis presenting to the University of California, Davis VMTH, to horses with colic of other causes. Data were collected on 61 horses with enterolithiasis and 75 controls via evaluation of patient records and questionnaires completed by owners at the time of admission. Following multiple logistic regression analysis, the following factors were found to be significantly associated with enterolithiasis: feeding > or = 50% of the diet as alfalfa; feeding <50% of the diet as oat hay; feeding <50% of the diet as grass hay; and lack of daily access to pasture grazing.

Subsequent criminal activity among violent misdemeanants who seek to purchase handguns: risk factors and effectiveness of denying handgun purchase.

CONTEXT: Some states prohibit the purchase of handguns by persons convicted of selected misdemeanor crimes, but most do not. California has denied handgun purchases by violent misdemeanants since 1991; the effectiveness of these policies is unknown. OBJECTIVE: To determine the risk factors for new criminal activity among violent misdemeanants who seek to purchase handguns and whether denial of handgun purchase by violent misdemeanants affects their risk of arrest for new crimes, particularly gun and/or violent crimes. DESIGN: Retrospective, population-based cohort study. SETTING AND SUBJECTS: Persons aged 21 to 34 years who sought to purchase a handgun through a licensed dealer in California during 1989-1991 and who had at least 1 violent misdemeanor conviction in the preceding 10 years. The study cohorts consisted of 986 persons whose purchase applications were made in 1991 and were denied (denied persons) and 787 persons whose purchase applications were made in 1989-1990 and were approved (purchasers). MAIN OUTCOME MEASURES: Incidence and relative risk of first arrest in California for new gun and/or violent crimes and for nongun, nonviolent crimes during a 3-year follow-up after actual or attempted handgun purchase. RESULTS: During the 3-year follow-up, 546 (33.0%) of 1654 subjects with follow-up information were arrested for a new crime, including 296 (31.9%) of 927 denied persons and 250 (34.4%) of 727 purchasers. After adjusting for differences in age, sex, and prior criminal history, purchasers were more likely than denied persons to be arrested for new gun and/or violent crimes (relative hazard [RH], 1.29; 95% confidence interval [CI], 1.04-1.60), but not for nongun, nonviolent crimes (RH, 0.96; 95% CI, 0.78-1.19). In both groups, risk of arrest was strongly related to age and number of convictions accrued prior to actual or attempted handgun purchase. CONCLUSION: Our results indicate that denial of handgun purchase to violent misdemeanants is associated with a specific decrease in risk of arrest for new gun and/or violent crimes.

Acute cervical spine injuries: prospective MR imaging assessment at a level 1 trauma center.

PURPOSE: To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospective detection of acute neck injury and to compare these findings with those of a comprehensive conventional radiographic assessment. MATERIALS AND METHODS: Conventional radiography and MR imaging were performed in 199 patients presenting to a level 1 trauma center with suspected cervical spine injury. Weighted sensitivities and specificities were calculated, and a weighted average across eight vertebral levels from C1 to T1 was formed. Fourteen parameters indicative of acute injury were tabulated. RESULTS: Fifty-eight patients had 172 acute cervical injuries. MR imaging depicted 136 (79%) acute abnormalities and conventional radiography depicted 39 (23%). For assessment of acute fractures, MR images (weighted average sensitivity, 43%; CI: 21%, 66%) were comparable to conventional radiographs (weighted average sensitivity, 48%; CI: 30%, 65%). MR imaging was superior to conventional radiography in the evaluation of pre- or paravertebral hemorrhage or edema, anterior or posterior longitudinal ligament injury, traumatic disk herniation, cord edema, and cord compression. Cord injuries were associated with cervical spine spondylosis (P < .05), acute fracture (P < .001), and canal stenosis (P < .001). CONCLUSION: MR imaging is more accurate than radiography in the detection of a wide spectrum of neck injuries, and further study is warranted of its potential effect on medical decision making, clinical outcome, and cost-effectiveness.

Evaluation of enterolithiasis in equids: 900 cases (1973-1996).

OBJECTIVE: To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. DESIGN: Retrospective study. ANIMALS: 900 equids with enterolithiasis. PROCEDURE: Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. RESULTS: Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study population, compared with the hospital population. The mean age of equids with enterolithiasis was 11.4 years. The most common historic findings were signs of intermittent colic (33.3%) and passage of enteroliths in the feces (13.5%). Physical examination findings were similar to those found in equids with other forms of nonstrangulating large colon obstructive disease. Fifteen percent (131) developed gastrointestinal tract rupture caused by an enterolith that necessitated euthanasia. Short-term and 1-year survival rates for equids undergoing celiotomy for treatment of enterolithiasis and recovering from anesthesia were excellent (96.2 and 92.5%, respectively), and postoperative complications were uncommon. Recurrence of enterolithiasis was identified in 7.7% of the study population. CLINICAL IMPLICATIONS: Results indicated that shortterm and 1-year survival rates for equids undergoing surgery for enterolithiasis are excellent. Identification of signalment, history, and management factors may help identify equids with a high risk for development of enterolithiasis.

Criminal activity and assault-type handguns: a study of young adults.

STUDY OBJECTIVE: We studied a population of young adults who legally purchased handguns to determine whether an association exists between the purchase of an assault-type handgun and prior or subsequent criminal activity. METHODS: We conducted a longitudinal study of 5,360 legally authorized purchasers of handguns in California in 1988 who were younger than 25 years at the time of purchase. Our main outcome measures were (1) adjusted relative risk (RR) for the purchase of an assault-type handgun for subjects with a criminal history compared with subjects without such a history and (2) adjusted RR for new criminal activity during the 3 years after handgun purchase for purchasers of assault-type handguns compared with purchasers of other handguns. RRs were adjusted for sex and race/ethnicity. RESULTS: Handgun purchasers with a criminal history were more likely than those with no criminal history to purchase assault-type handguns (4.6% and 2.0%, respectively; RR = 2.0; 95% confidence interval [CI] 1.5 to 2.8). Among handgun purchasers who had a criminal history, purchasers of assault-type handguns were more likely than purchasers of other handguns to be charged with new offenses (RR = 1.5; 95% CI, 1.3 to 1.9), including offenses involving firearms of violence (RR = 1.7; 95% CI, 1.3 to 2.20. Among those who had previously been charged with Violent Crime Index offenses (murder, rape, robbery, aggravated assault), those who purchased assault-type handguns were more than twice as likely as purchasers of other handguns to be charged with a new offense (RR = 2.3; 95% CI, 1.5 to 3.4) and three times as likely to be charged with a new offense involving firearms or violence (RR = 3.0, 95% CI, 1.9 to 4.6). CONCLUSION: In this population, the purchase of an assault-type handgun was associated with both prior and subsequent criminal activity.

Weapons of choice: previous criminal history, later criminal activity, and firearm preference among legally authorized young adult purchasers of handguns.

OBJECTIVE: To determine whether there is an association between criminal activity and preference for a particular class of handgun among young adults who purchase handguns legally. DESIGN: Historical cohort study. MATERIALS AND METHODS: Subjects were 5,360 authorized purchasers of handguns in California in 1988 who were 21 to 25 years of age, divided into two groups: all eligible purchasers with a previous criminal history (n = 2,765), and a random sample of purchasers with no such history (n = 2,595). Handguns were classified as small and inexpensive or larger and expensive. Associations were assessed by relative risks adjusted for gender and race or ethnicity. MEASUREMENTS AND MAIN RESULTS: Handgun purchasers with a previous criminal history were more likely than those without such a history to purchase a small, inexpensive handgun (relative risk (RR) = 1.28; 95% confidence interval (CI), 1.16-1.42). Among handgun purchasers with no previous criminal history, those who purchased a small, inexpensive handgun were more likely than purchasers of other handguns to be charged with new crimes after handgun purchase (RR = 1.73; 95% CI, 1.34-2.24) and were nearly twice as likely to charged with new crimes involving firearms or violence (RR = 1.93; 95% CI, 1.38-2.69). CONCLUSION: In this population, criminal activity both before and after handgun purchase was associated with a preference for small, inexpensive handguns.

Prior misdemeanor convictions as a risk factor for later violent and firearm-related criminal activity among authorized purchasers of handguns.

CONTEXT: Under current federal law, many persons with prior convictions for misdemeanor offenses pass criminal records background checks and legally purchase handguns. OBJECTIVE: To determine whether authorized handgun purchasers with prior misdemeanor convictions are more likely than those with no criminal history to be charged with new crimes, particularly offenses involving firearms and violence. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: A total of 5923 authorized purchasers of handguns in California in 1977 who were younger than 50 years, identified by random sample. MAIN OUTCOME MEASURES: Incidence and relative risk (RR) of first charges for new criminal offenses after handgun purchase. RESULTS: Of the 5923 authorized purchasers, 3128 had at least 1 conviction for a misdemeanor offense prior to handgun purchase, and 2795 had no prior criminal history. Follow-up to the end of the 15-year observation period or to death was available for 77.8% of study subjects and for a median 8.9 years for another 9.6%. Handgun purchasers with at least 1 prior misdemeanor conviction were more than 7 times as likely as those with no prior criminal history to be charged with a new offense after handgun purchase (RR, 7.5; 95% confidence interval [CI], 6.6-8.7). Among men, those with 2 or more prior convictions for misdemeanor violence were at greatest risk for nonviolent firearm-related offenses such as weapon carrying (RR, 11.7; 95% CI, 6.8-20.0), violent offenses generally (RR, 10.4; 95% CI, 6.9-15.8), and Violent Crime Index offenses (murder or non-negligent manslaughter, forcible rape, robbery, or aggravated assault) (RR, 15.1; 95% CI, 9.4-24.3). However, even handgun purchasers with only 1 prior misdemeanor conviction and no convictions for offenses involving firearms or violence were nearly 5 times as likely as those with no prior criminal history to be charged with new offenses involving firearms or violence. CONCLUSIONS: Handgun purchasers with prior misdemeanor convictions are at increased risk for future criminal activity, including violent and firearm-related crimes.

Spinal level of fetal myelomeningocele: does it influence ventricular size?

OBJECTIVE: Our objective was to determine whether the level of the spinal defect influences ventricular size in fetuses with myelomeningoceles. MATERIALS AND METHODS: Sonograms of 51 fetuses with open spina bifida were reviewed to determine the gestational age, ventricular atrial diameter, severity of posterior fossa deformity, and the level of the spinal defect. Four categories for spinal defect level were used: sacral, low lumbar, high lumbar, and thoracic. Regression models for ventricular atrial diameter were fit, adjusting for gestational age, posterior fossa deformity, and spinal defect level. A Fisher's exact test was used to investigate a relationship between the level of the spinal defect and the severity of the posterior fossa deformity. RESULTS: Spinal defect level was distributed among the four categories as follows: sacral (n = 7), low lumbar (n = 30), high lumbar (n = 10), and thoracic (n = 4). The level of the spinal defect did not significantly affect ventricular size (p > .1), and the level of the spinal defect did not show any relationship to the severity of the posterior fossa deformity (p > .8). CONCLUSION: The level of the spinal defect does not independently affect the degree of ventriculomegaly or severity of the posterior fossa deformity in fetuses with myelomeningoceles.

High-speed exercise history and catastrophic racing fracture in thoroughbreds.

OBJECTIVE: To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds. ANIMALS: 64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants. PROCEDURE: Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by paired t-test and studied in detail, using conditional logistic regression. RESULTS: High total and high average daily rates of exercise distance accumulation within a 2-month period were associated with higher risks for FSI during racing, yet career patterns, such as age at first race or total proportion of career spent laid up, were not found to be associated with risk for FSI. A horse that had accumulated a total of 35 furlongs of race and timed-work distance in 2 months, compared with a horse with 25 furlongs accumulated, had an estimated 3.9-fold increase in risk for racing-related FSI (95% confidence interval = 2.1, 7.1). A horse that had accumulated race and timed-work furlongs at an average rate of 0.6 furlong/d within a 2-month period, compared with a horse with an average of 0.5 furlong/d, had an estimated 1.8-fold increase in risk for racing-related FSI (95% confidence interval = 1.4, 2.6). CONCLUSIONS AND CLINICAL RELEVANCE: Thoroughbred racehorses that either accumulate large total high-speed distances or rapidly accumulate high-speed distances within a 2-month period may be at increased risk for FSI during racing.

Orthodontics and temporomandibular joint internal derangement.

The purpose of this investigation is to compare the prevalence of internal derangement of the temporomandibular joints (TMJ) in asymptomatic volunteers versus symptomatic subjects using magnetic resonance imaging (MRI), with a detailed comparison to clinical signs and symptoms and with attention to a prior history of orthodontic treatment. Bilateral MRI scans were obtained of the TMJs in 76 asymptomatic volunteers and 102 symptomatic patients. A comparison was made to the clinical signs and symptoms, a history of orthodontic treatment, and to the MR findings. The MRI scans were reviewed using established criteria for disk displacement and the reviewers were blinded as to the clinical information. Our results show a prevalence of disk displacement in 25 of 76 (33%) volunteers and 79 of 102 (77%) patients with a statistically significant difference (p < 0.001). No statistical link was noted between a history of prior orthodontic treatment and internal derangement of the TMJ.

Anatomic disorders of the temporomandibular joint disc in asymptomatic subjects.

PURPOSE: This study determined the prevalence and specific anatomic types of disc displacement in asymptomatic versus symptomatic subjects using magnetic resonance imaging (MRI). PATIENTS AND METHODS: A detailed MRI assessment was performed on both temporomandibular joints (TMJ) in 76 volunteers and 102 successive patients. Attention was placed on the functional aspects of disc displacement with and without reduction and on the anatomic aspects of disc displacement in the anterior, lateral, medial, anterolateral, and anteromedial directions. These assessments were made by radiologists blinded to the clinical information. RESULTS: Disc displacement was found in at least one joint in 25 of 76 (33%) of asymptomatic subjects and 79 of 102 (77%) of symptomatic subjects. The anatomic types of disc displacement between groups was not statistically significant (P = .55). However, there was a significant difference between asymptomatic and symptomatic subjects, with an odds ratio of 3.91 for disc displacement with reduction and 42.71 for disc displacement without reduction (P < .001). CONCLUSION: Although there was a 33% prevalence of disc displacement in asymptomatic volunteers, there was a highly significant difference in the prevalence of internal derangement in symptomatic subjects. Bruxing was statistically linked to TMJ disc displacement and could explain the anatomic variation in abnormal disc position.

Indirect computed tomography lymphography using iodinated nanoparticles to detect cancerous lymph nodes in a cutaneous melanoma model.

RATIONALE AND OBJECTIVES: To evaluate differences in contrast uptake in normal and cancerous lymph nodes on indirect computed tomography (CT) in swine, we conducted lymphographic examinations after subcutaneous injection of a lymphotropic iodinated nanoparticle suspension. METHODS: Perilesional subcutaneous contrast injections (2 ml per lesion) of a 15% wt/vol iodinated nanoparticle suspension were made in immature Sinclair miniature swine (n = 5) with cutaneous melanomas. Average attenuation, iodine concentration, node volume, and total iodine uptake were estimated on the CT scans for each opacified lymph node 24 hr after injection. Nodes were classified as normal or cancerous microscopically, and the percentage of tumor replacement was estimated in cancerous nodes. RESULTS: Average attenuation and iodine concentration were higher in normal nodes, and total iodine uptake was higher in cancerous nodes with greater than 25% replacement (p < .05). Architectural alterations in opacified cancerous nodes included medullary filling defects, expansile cortical lesions, and disruption of corticomedullary junctions. CONCLUSION: Quantitative and qualitative differences in iodinated nanoparticle enhancement characteristics are useful in distinguishing between normal and cancerous lymph nodes on indirect CT lymphography examinations.

Indirect computed tomography lymphography using iodinated nanoparticles: time and dose response in normal canine lymph nodes.

RATIONALE AND OBJECTIVES: We evaluated the effect of time and dose on lymph node iodine uptake after subcutaneous or submucosal administration of iodinated nanoparticles used for computed tomography lymphography. METHODS: We injected 0.1-6 ml of a 15% wt/vol iodinated nanoparticle suspension into the distal extremities subcutaneously (n = 5) or into the buccal submucosa (n = 7) of normal dogs. Precontrast and 4, 12, 24, and 48 hr after contrast administration, CT scans of opacified lymph nodes were obtained. Iodine concentration, node volume, and total iodine uptake were estimated for each node. RESULTS: All estimated parameters increased between 4 and 12 hr postcontrast (p < .05), with no significant increase thereafter. At 24 hr postcontrast, iodine concentration ranged from 0.01 to 16.1 mg/ml (47-568 Hounsfield units). The average iodine concentration and total iodine uptake increased with contrast dose (p < .05) for all lymph node groups evaluated. Node opacification also revealed internal architectural detail. CONCLUSION: Subcutaneous and submucosal injections of iodinated nanoparticles result in a dose-dependent iodine uptake in targeted lymph nodes. In addition, architectural detail within opacified nodes can be visualized.

Quinidine administration increases steady state serum digoxin concentration in horses.

The aim of this study was to determine if quinidine administration increases steady state serum digoxin concentration in horses. Digoxin (0.01 mg/kg q. 12 h per os) was administered to 6 horses for 7 days. Steady state was confirmed by identifying statistically indistinguishable peak and trough serum digoxin concentrations on Days 4, 5, and 6. On Day 6, serum digoxin concentration was measured at baseline and 0.25, 0.5, 1, 2, 4, 6, 8 and 12 h after digoxin administration. On Day 7, quinidine (20 g at baseline and 10 g at 2, 4 and 6 h) was administered per os and serum digoxin concentration was measured at the same time intervals. Creatinine and renal digoxin clearances were measured on Days 6 and 7. Results indicated that there was approximately a doubling of serum digoxin concentration (from mean +/- s.d. 2.57 +/- 0.96 ng/ml at baseline to 4.28 +/- 1.31 at 15 min and 5.98 +/- 1.21 ng/ml at 30 min) after starting the administration of quinidine. This elevation persisted for the 12 h after starting quinidine administration. Renal digoxin and endogenous creatinine clearances decreased but the decrease in digoxin clearance was greater. Serum quinidine concentration achieved the therapeutic range (2-6 micrograms/ml) in 5 of the 6 horses. In summary, similar to findings in other species, quinidine administration increases steady state serum digoxin concentration in horses and this occurs, at least in part, due to a decrease in renal digoxin clearance. Some of the decrease in renal clearance is due to decreased glomerular filtration which is dissimilar to findings in other species.

Indirect computed tomography lymphography of subdiaphragmatic lymph nodes using iodinated nanoparticles in normal dogs.

RATIONALE AND OBJECTIVES: We evaluated the imaging characteristics of an iodinated particulate contrast agent for indirect computed tomography (CT) lymphography of normal subdiaphragmatic lymph nodes in dogs. METHODS: Four milliliters of a 15% (wt/vol) iodinated nanoparticle suspension was injected into the gastric, colonic, rectal, or cervical submucosa, loose paraprostatic fascia, or metatarsal subcutaneous tissues in 10 healthy beagles. Endoscopic, CT, or ultrasound guidance was used when necessary to facilitate contrast agent delivery. CT and radiographic images were obtained prior to contrast administration and at 4 hr, 24 hr, and 7 days postcontrast injection. Postmortem examinations were then conducted. RESULTS: CT images showed enhancement of regional lymph nodes draining the various injection sites. The mean attenuation of opacified nodes was 678 +/- 463 Hounsfield units 24 hr after injection and remained elevated 7 days later. Lymph node opacification on CT images correlated well with the node location observed on postmortem examinations. CONCLUSION: Subdiaphragmatic lymph nodes can be effectively opacified using an iodinated nanoparticle contrast agent for indirect CT lymphography.