Surgery of the spine in myelodysplasia. An overview

Significant spinal deformity is particularly common in nonambulatory patients with myelodysplasia. Progressive deformity may be caused by congenital anomalies, paralytic collapse, hip contractures, or spinal cord tethering. Existing or projected functional impairment should be the principle indication for treatment. Surgical treatment is complicated by poor soft tissue coverage, associated contractures, lack of sensation, weak bone, and absence of posterior elements. Successful fusion can be achieved by circumferential (anterior and posterior) fusion and current rigid segmental instrumentation. The unique deformities and bony anatomy require individualized techniques to achieve fixation.     

Imaging of delta- and mu-opioid receptors in temporal lobe epilepsy by positron emission tomography

The authors report the postoperative magnetic resonance (MR) imaging findings in 36 patients with advanced Parkinson's disease who underwent unilateral microelectrode-guided posteroventral pallidotomy. The lesions were placed within 1 mm of the ventral border of the globus pallidus internus (GPi) to include pallidothalamic outflow pathways. Sequential MR studies were obtained within 1 to 3 days postoperatively and at 6-month follow-up examination. Thirty-four (94%) of the 36 patients enjoyed sustained moderate or marked improvement of their parkinsonian symptoms 6 months postoperatively. Transient side effects occurred in five patients (14%), but there were no persistent complications. The pallidal radiofrequency lesions were prolate spheroid shaped and were composed of three concentric zones in the early postoperative studies. The mean volume of the middle zone, corresponding to the area of hemorrhagic coagulation necrosis, was 44.4 +/- 17.6 mm3; the mean lesion volume as defined by the outer zone, corresponding to perilesional edema, was 262.2 +/- 111.6 mm3. Additional edema spreading to the internal capsule was noted in 32 of 34 cases and to the optic tract in 11 of 34 cases. In two patients small ischemic infarctions involving the corona radiata were found, and in one a venous infarction was detected. Ischemic infarction resulted in mild transient Broca's aphasia in one patient, but there was no detectable neurological deficit in the other two. The mean volume of late-phase (6 months) lesions was 22 +/- 28.8 mm3. In three patients no lesion was identified despite sustained clinical improvement. The lesion was located in the posteroventral GPi in all cases except in one patient in whom it was confined to the GP externus (GPe). This 49-year-old woman did not experience sustained benefit. The authors found no consistent correlations between lesion size and location and clinical outcome as measured by a global outcome score, the Unified Parkinson's Disease Rating Scale motor, activities of daily living, and bradykinesia "off" scores or rating of dyskinesias. Lesioning of pallidal and subpallidal pathways may contribute to the sustained clinical benefit in this series. Magnetic resonance imaging analysis showed that intraoperative microelectrode recording facilitated accurate placement of the lesion in this critical area.     

Influence of fat source and sorghum grain treatment on performance and digestibilities of high yielding dairy cows

Forty-eight lactating Holstein cows averaging 81 d in milk were allotted to eight blocks based on milk yield during the 14-d pretreatment period and randomly assigned to six treatment groups in a 2 x 3 factorial arrangement of treatments for 64 d. Factors were type of sorghum grain processing [dry-rolled vs. steam-flaked; fed at 34% of dry matter (DM) in a total mixed ration (TMR) based on alfalfa] and type of supplemental fat (2.5% of DM as cottonseed oil, tallow, or prilled fatty acids). Compared with dry-rolled sorghum, steam-flaked sorghum did not affect milk yield, fat percentage, or fat yield but did increase milk protein percentage, body weight gains, and estimated net energy for lactation (22%). Fat source did not affect lactational response, but, compared with tallow, prilled fatty acids tended to decrease DM intake. Steam-flaked sorghum, compared with dry-rolled sorghum, increased digestibilities of DM, organic matter, crude protein, and starch, regardless of fat source. The TMR containing prilled fat had lower digestibilities of DM and organic matter than did TMR containing cottonseed oil or tallow; and TMR containing prilled fat had lower digestibilities of crude protein and total fatty acids than did TMR containing tallow. This study showed that steam-flaking of sorghum grain increased milk protein content, body weight gains, and estimated net energy for lactation, regardless of dietary fat source.     

Observations on catalysis by hammerhead ribozymes are consistent with a two-divalent-metal-ion mechanism

Significant cleavage by hammerhead ribozymes requires activation by divalent metal ions. Several models have been proposed to account for the influence of metal ions on hammerhead activity. A number of recent papers have presented data that have been interpreted as supporting a one-metal-hydroxide-ion mechanism. In addition, a solvent deuterium isotope effect has been taken as evidence against a proton transfer in the rate-limiting step of the cleavage reaction. We propose that these data are more easily explained by a two-metal-ion mechanism that does not involve a metal hydroxide, but does involve a proton transfer in the rate-limiting step.     

Cardiac tamponade in Taiwan

We describe two sibs with chorioretinal dystrophy, hypogonadotrophic hypogonadism, and cerebellar ataxia, Boucher-Neuh?user syndrome, a rare but distinct pleiotropic single gene disorder with an autosomal recessive pattern of inheritance. The cases presented illustrate that this syndrome is still poorly recognised. We provide a review and analysis of previously reported cases and the differential diagnosis, which might aid in the identification of additional cases.     

Generation of biotin/avidin/enzyme nanostructures with maskless photolithography

Micrometer-sized domains of a carbon surface are modified to allow derivatization to attach redox enzymes with biotin/avidin technology. These sites are spatially segregated from and directly adjacent to electron transfer sites on the same electrode surface. The distance between these electron transfer sites and enzyme-loaded domains must be kept to a minimum (e.g., less than 5 microns) to maintain the fast response time and high sensitivity required for the measurement of neurotransmitter dynamics. This is accomplished through the use of photolithographic attachment of photobiotin using an interference pattern from a UV laser generated at the electrode surface. This will allow the construction of microscopic arrays of active enzyme sites on a carbon fiber substrate while leaving other sites underivatized to facilitate electron transfer reactions of redox mediators, thus maximizing enzyme activity and detection of the enzyme mediator. The ultimate sensitivity of these sensors will be realized only through careful characterization of the carbon electrode surface with respect to its chemical structure and electron transfer properties following each step of the enzyme immobilization process. The characterization of specific modifications of micrometer regions of the carbon surface requires analytical methodology that has both high spatial resolution and sensitivity. We have used fluorescence microscopy with a cooled CCD imaging system to visualize the spatial distribution of enzyme immobilization sites (indicated by fluorescence from Texas Red-labeled avidin) across the carbon surface. The viability of the enzyme attached to the surface in this manner was demonstrated by imaging the distribution of an insoluble, fluorescent product. An atomic force microscope was used to obtain high-resolution images that probe the heterogeneity of the enzyme sites.     

Retropharyngeal pseudomeningocele after atlanto-occipital dislocation: report of two cases

OBJECTIVE AND IMPORTANCE: We report two cases of retropharyngeal pseudomeningocele after atlanto-occipital dislocation. This is rare, with only one other reported case in the literature. CLINICAL PRESENTATION: We report two patients who presented after blunt cervical and head trauma. Plain films revealed that each patient had atlanto-occipital dislocation. Subsequent magnetic resonance imaging revealed the delayed development of retropharyngeal pseudomeningocele. Concomitant hydrocephalus was noted in both patients. INTERVENTION: The surviving patient showed marked neurological improvement and resolution of his pseudomeningocele after ventriculoperitoneal shunting. CONCLUSION: For patients with closed head injuries who develop posttraumatic pseudomeningocele, we recommend cranial computed tomography to assess for the presence of hydrocephalus. In patients with atlanto-occipital dislocation, delayed neurological deterioration warrants magnetic resonance imaging of the craniocervical junction to rule out posttraumatic pseudomeningocele.     

Persistence of porcine reproductive and respiratory syndrome virus in intensive farrow-to-finish pig herds

We analyzed signal-averaged electrocardiograms (ECG) obtained in 50 patients with recent myocardial infarction (RMI: 25 anterior and 25 inferior) and 20 normal subjects to determine the relationship between the initial portion of the signal-averaged QRS complex and cardiac function and infarct size. We examined (1) the root mean square voltage (RMS10-40, microV), (2) the integration (A10-40, microV.msec) at 10-msec intervals over the first 40 msec of the signal-averaged QRS complex, and (3) the intervals (T) of the magnitude of the signal-averaged ECG achieved at 10-microV intervals over the first 40 microV (T10-40, msec). The mean RMS10-40 (p < 0.01) and A10-40 (A10, p < 0.05; A20-40, p < 0.01) were significantly lower and the T10-40 (p < 0.01) was significantly longer in RMI patients than in normal subjects. The RMS10-40 (p < 0.01) and A10-40 (p < 0.05) were significantly lower and the T10-40 (T10.20, p < 0.01; T30.40, p < 0.05) was significantly longer in patients with anterior RMI patients than in patients with inferior RMI. The A30 was correlated with the ejection fraction and total creatine kinase (CK) release in all patients (r = 0.73, and -0.78, respectively, p < 0.001). These results suggest that the A30 may be an important predictor of ventricular dysfunction and infarct size in patients with RMI.