Enhancement of sub-thermal neutron flux through cold polyethylene

Total thermal neutron cross section measurements serve as the primary means of validation for thermal neutron scattering kernels, an important quantity for neutron transport calculations. In an effort to improve the quality of thermal neutron scattering kernels, researchers at Rensselaer Polytechnic Institute (RPI) designed and constructed a polyethylene based cold moderation system to enhance neutron flux below 10 meV when coupled with the Enhanced Thermal Target (ETT) at the RPI Gaerttner LINAC. The final design yielded an increase in sub-thermal neutron flux (below 10 meV) by a factor of 4.5 for a moderator temperature of 37.5 K relative to the ETT alone. A further increase to a factor of 6 is expected after a minor geometry modification and decrease in polyethylene temperature to 25 K. This novel capability will be used to conduct total thermal neutron cross section measurements from 0.0005–10 eV for different materials including moderator materials.

Delayed Single Kirschner Wire Compression Technique for Mallet Fracture

Twenty-four mallet fractures which involved at least one third % of the articular surface of the distal interphalangeal joint were treated by open reduction and internal fixation using a single double-ended Kirschner wire at a mean of 9 days after injury (range 4–15). At a mean follow-up of 43 (range 12–18) months the active range of motion, pain and the Warren and Norris criteria were evaluated. The mean active range of motion was from −2° extension (range 0–10°) to 72° flexion (range 50–90°). Nineteen patients were pain free and five suffered from mild pain during strenuous work. The Warren and Norris results were successful in 22 and improved in two cases. Radiographs showed, that all the fractures united in a near-anatomic position but with joint narrowing in six digits.

Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4

We report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by the [Formula: see text] states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump-hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps-1.5 ns.

High contrast x-ray speckle from atomic-scale order in liquids and glasses

The availability of ultrafast pulses of coherent hard x rays from the Linac Coherent Light Source opens new opportunities for studies of atomic-scale dynamics in amorphous materials. Here, we show that single ultrafast coherent x-ray pulses can be used to observe the speckle contrast in the high-angle diffraction from liquid Ga and glassy Ni(2)Pd(2)P and B(2)O(3). We determine the thresholds above which the x-ray pulses disturb the atomic arrangements. Furthermore, high contrast speckle is observed in scattering patterns from the glasses integrated over many pulses, demonstrating that the source and optics are sufficiently stable for x-ray photon correlation spectroscopy studies of dynamics over a wide range of time scales.

Progress towards discovery of antifibrotic drugs targeting synthesis of type I collagen

Type I collagen is the most abundant protein in human body. Fibrosis is characterized by excessive synthesis of type I collagen in parenchymal organs. It is a leading cause of morbidity and mortality worldwide, about 45% of all natural deaths are attributable to some fibroproliferative disease. There is no cure for fibrosis. To find specific antifibrotic therapy targeting type I collagen, critical molecular interactions regulating its synthesis must be elucidated. Type I and type III collagen mRNAs have a unique sequence element at the 5' end, the 5' stem-loop. This stem-loop is not found in any other mRNA. We cloned LARP6 as the protein which binds collagen 5' stem-loop with high affinity and specificity. Mutation of the 5' stem-loop or knock down of LARP6 greatly diminishes collagen expression. Mice with mutation of the 5' stem-loop are resistant to development of liver fibrosis. LARP6 associates collagen mRNAs with filaments composed of nonmuscle myosin; disruption of these filaments abolishes synthesis of type I collagen. Thus, LARP6 dependent collagen synthesis is the specific mechanism of high collagen expression seen in fibrosis. We developed fluorescence polarization (FP) method to screen for drugs that can inhibit binding of LARP6 to 5' stem-loop RNA. FP is high when LARP6 is bound, but decreases to low levels when the binding is competed out. Thus, by measuring decrease in FP it is possible to identify chemical compounds that can dissociate LARP6 from the 5' stem-loop. The method is simple, fast and suitable for high throughput screening.

Role of STAT6 and SMAD2 in a model of chronic allergen exposure: a mouse strain comparison study

BACKGROUND

Asthma is a disease characterized by variable and reversible airway obstruction and is associated with airway inflammation, airway remodelling (including goblet cell hyperplasia, increased collagen deposition and increased smooth muscle mass) and increased airway responsiveness. It is believed that airway inflammation plays a critical role in the development of airway remodelling, with IL-13 and TGF-beta1 pathways being strongly associated with the disease progression. Mouse models of asthma are capable of recapitulating some components of asthma and have been used to look at both IL-13 and TGF-beta1 pathways, which use STAT6 and SMAD2 signalling molecules, respectively.

OBJECTIVES

Using brief and chronic models of allergen exposure, we utilized BALB/c and C57Bl/6 to explore the hypothesis that observed differences in responses to allergen between these mouse strains will involve fundamental differences in IL-13 and TGF-beta1 responses.

METHODS

The following outcome measurements were performed: airway physiology, bronchoalveolar lavage cell counts/cytokine analysis, histology, immunoblots and gene expression assays.

RESULTS

We demonstrate in BALB/c mice an IL-13-dependent phosphorylation of STAT6, nuclear localized in inflammatory cells, which is associated with indices of airway remodelling and development of airway dysfunction. In BALB/c mice, phosphorylation of SMAD2 is delayed relative to STAT6 activation and also involves an IL-13-dependent mechanism. In contrast, despite an allergen-induced increase in IL-4, IL-13 and eosinophils, C57Bl/6 demonstrates a reduced and distinct pattern of phosphorylated STAT6, no SMAD2 phosphorylation changes and fail to develop indices of remodelling or changes in airway function.

CONCLUSION

The activation of signalling pathways and nuclear translocation of signalling molecules downstream of IL-13 and TGF-beta1 further support the central role of these molecules in the pathology and dysfunction in animal models of asthma. Activation of signalling pathways downstream from IL-13 and TGF-beta1 may be more relevant in disease progression than elevations in airway inflammation alone.

[Dorsolateral dislocation of the proximal interphalangeal joint: closed reduction and early active motion versus static splinting]

In this follow-up examination, the outcome of two conservative treatment regimens (immobilisation versus early active motion) were evaluated in 50 patients with dorsolateral dislocation of the proximal interphalangeal joint after a mean follow-up time of 7.9 years. The aim of this study was to prove whether early mobilisation results in better clinical outcome compared to prolonged immobilisation. In group A, 25 patients were treated by static splinting in a cast for four weeks. At follow-up, 21 patients were free of pain, three patients complained of pain following maximum loading and one patient experienced permanent pain. The mean range of motion was 89.4 degrees, the mean lack of extension was 12.7 degrees and the mean joint circumference was 3.4 mm thicker than the uninjured side. Pinch power was reduced to 78 % of the uninjured side. All joints were clinically stable. Degenerative arthritis was seen in five patients. In group B, 25 patients were treated by dorsal block splinting of the interphalangeal joint. The patients were allowed to extend their finger and to perform daily active exercises of the injured joint. At follow-up, eighteen patients were pain free, five experienced pain after maximum loading and two patients complained of permanent pain. The mean range of motion was 96.6 degrees, the mean limitation of extension was 5.3 degrees and the mean joint circumference was 4.1 mm thicker than on the uninjured side. Pinch power was reduced to 85 % of the uninjured side. All joints were clinically stable. Degenerative arthritis was seen in six patients. Early active motion following dorsolateral dislocation of the proximal interphalangeal joint leads to significantly superior results regarding the active range of motion and pinch power.

[MR imaging for the evaluation of accompanying injuries in cases of distal forearm fractures in children and adolescents]

INTRODUCTION

The study was made to evaluate the role of MR imaging in pediatric distal forearm fractures by comparison with the findings of plain radiographs and MRI.

MATERIAL AND METHOD

38 patients (27 boys and 11 girls, mean age of 12 years, range 7 to 15 years) with radiographically open distal radius and ulna growth plates requiring first aid for a fracture of the distal third of the forearm, were included in this study. The fractures were diagnosed on plain radiographs and conservative treatment was performed. In 35 patients MR imaging was performed within 3 weeks after the accident and in 3 patients MRI was performed after 6 to 9 weeks because of persistent wrist pain.

RESULTS

Fifteen Salter/Harris II injuries of the radius and 1 of the ulna, 1 torus fracture of the radius and 2 of the ulna, 12 greenstick fractures of the radius and 3 of the ulna, 10 complete displaced radius fractures and 15 ulnar styloid fractures were found on plain radiographs. Twelve patients had evidence of associated triangular fibrocartilage complex (TFCC) lesions in MRI, there was no statistical correlation between TFCC lesions and fracture types, fracture dislocations or patients age (p > 0.5). One patient had an avulsion of the radioscaphocapitate ligament from the radius accompanying a greenstick fracture of the distal radius. 19 bone bruises and two radiographically occult fractures were identified. In 2 patients, a bone marrow oedema was seen in the radial epiphysis immediately adjacent to the germinal zone of the growth plate. In these patients premature physeal arrest occurred.

CONCLUSION

MRI plays an important role in the evaluation of acute pediatric wrist injuries. It allows a better evaluation of osseous lesions than plain radiographs. In our study, a tear of the triangular fibrocartilage complex accompanied distal radius fractures in 32 % of patients. Simultaneous rupture of the TFCC insertion in the fovea ulnaris and ulnar styloid fracture lead to destabilisation of the distal radioulnar joint (DRUJ).

Reconstruction of the digital flexor pulley system: a retrospective comparison of two methods of treatment

The rare injury of closed rupture of the A2 and A3 flexor pulleys was treated using two non-encircling techniques of pulley reconstruction. Thirteen patients were treated with an extensor retinaculum graft (Group A). At a mean follow-up time of 48 months, the average PIP flexion was 97%, the power grip strength 96%, the pinch grip strength 100% and the thickening 94% of the uninjured side. Ten patients were treated with a free palmaris longus tendon grafts (Group B). At a mean follow-up time of 57 months, the average PIP flexion was 94%, the power grip strength 98%, the pinch grip strength 100% and the thickening 95% of the uninjured side. In both groups, finger extension was unrestricted. The Buck Gramcko score included 10 excellent, two good and one fair result in Group A and seven excellent, two good and one fair result in Group B. Both techniques proved beneficial. All climbers returned to their previous standard and all non-climbers regained full finger dexterity in their previous job.

Amyloplast to chromoplast conversion in developing ornamental tobacco floral nectaries provides sugar for nectar and antioxidants for protection

Tobacco floral nectaries undergo changes in form and function. As nectaries change from green to orange, a new pigment is expressed. Analysis demonstrated that it is β-carotene. Plastids undergo dramatic changes. Early in nectary development, they divide and by stage 9 (S9) they are engorged with starch. About S9, nectaries shift from quiescent anabolism to active catabolism resulting in starch breakdown and production of nectar sugars. Starch is replaced by osmiophilic bodies, which contain needle-like carotenoid crystals. Between S9 and S12, amyloplasts are converted to chromoplasts. Changes in carotenoids and ascorbate were assayed and are expressed at low levels early in development; however, following S9 metabolic shift, syntheses of β-carotene and ascorbate greatly increase in advance of expression of nectar redox cycle. Transcript analysis for carotenoid and ascorbate biosynthetic pathways showed that these genes are significantly expressed at S6, prior to the S9 metabolic shift. Thus, formation of antioxidants β-carotene and ascorbate after the metabolic shift is independent of transcriptional regulation. We propose that biosynthesis of these antioxidants is governed by availability of substrate molecules that arise from starch breakdown. These processes and events may be amenable to molecular manipulation to provide a better system for insect attraction, cross pollination, and hybridization.

Saccadic latency distributions in Parkinson's disease and the effects of L-dopa

Parkinson's disease (PD) is associated with a loss of central dopaminergic pathways in the brain leading to an abnormality of movement, including saccades. In PD, analysis of saccadic latency distributions, rather than mean latencies, can provide much more information about how the neural decision process that precedes movement is affected by disease or medication. Subject to the constraints of intersubject variation and reproducibility, latency distribution may represent an attractive potential biomarker of PD. Here we report two studies that provide information about these parameters, and demonstrate a novel effect of dopamine on saccadic latency, implying that it influences the neural decision process itself. We performed a detailed cross-sectional study of saccadic latency distributions during a simple step task in 22 medicated patients and 27 age-matched controls. This revealed high intersubject variability and an overlap of PD and control distributions. A second study was undertaken on a different population specifically to investigate the effects of dopamine on saccadic latency distributions in 15 PD patients. L-dopa was found to prolong latency, although the magnitude of the effect varied between subjects. The implications of these observations for the use of saccadic latency distributions as a potential biomarker of PD are discussed, as are the effects of L-dopa on neural decision making, where it is postulated to increase the criterion level of evidence required before the decision to move is made.

Multilobulated "flower" cells in a subcutaneous mass aspirate from a cat

An 8-year-old intact male cat was presented with a subcutaneous mass in the region of the right jugular vein. Cytologic and histopathologic examinations revealed cells with multilobulated nuclei (flower cells). Immunochemistry using a panel of markers showed vimentin-positivity on cytologic specimens, and postive staining for CD79a and BLA36 on histologic specimens. The final diagnosis was lymphoma of B-cell origin. We have observed similar multilobulated cells in ascites fluid, thoracic fluid, and peripheral blood from dogs and cats with a variety of lymphoid and myeloid neoplasms. Cells with multilobulated nuclei that resemble flower petals also have been described in humans. These cells are infrequently observed in canine and feline cytology specimens and require immunochemistry to determine their cell of origin.

Palmar locking plate for treatment of unstable dorsal dislocated distal radius fractures

INTRODUCTION

This study investigates the clinical and radiological results of open reduction and internal fixation of unstable distal radial fractures using a palmar placed interlocking plate system with no substitutes for treatment of the dorsal metaphyseal fracture void.

MATERIALS AND METHODS

Nineteen patients with a mean age of 61 years (range 49-78 years) and a dorsally displaced distal radial fracture were treated using a palmar placed 2.4 mm interlocking plate system. All 17 women and 2 men were followed up according to the study protocol. Standardised radiographs in anteroposterior and lateral projection were performed before reduction and at 2, 6, 12 and 24 weeks after surgery. Radiological measurements included palmar tilt, radial inclination and radial shortening as defined by ulnar variance and intra-articular steps. Clinical assessment included active range of motion (ARM) of the wrist, pain according to a visual analogue scale (VAS), grip power, working ability, Disability of Arm, Shoulder and Hand-Score (DASH Score) and Mayo Wrist Score.

RESULTS

At final follow-up after a minimum of 11 months, the palmar tilt was +1 degrees , radial inclination 19.8 degrees and ulnar variance 1.0 mm. Mean loss of palmar tilt measured 1.9 degrees , radial inclination 1.3 degrees and ulnar variance 0.4 mm. Mean wrist extension measured 58 degrees , wrist flexion 41 degrees , pronation 83 degrees and supination 84 degrees . The Mayo Wrist Score showed 21% excellent, 58% good, 16% fair and 5% poor results.

CONCLUSION

The treatment of unstable, dorsally dislocated, distal radius fractures AO types A3, C1 and C2, with a palmar placed 2.4 mm interlocking plate system and without additional treatment of the metaphyseal defects showed good radiological and functional results with minimal loss of reduction.

Dorsolateral dislocation of the proximal interphalangeal joint: closed reduction and early active motion or static splinting; a retrospective study

INTRODUCTION

In a follow-up examination 50 patients who had sustained dorsal dislocations of the proximal interphalangeal (PIP) joint, the results of two conservative therapy regimens, either immobilisation or early motion, were investigated. The patients were assigned randomly. The inclusion criteria were: adult patients over the age of 18 with isolated, acute, closed dorsolateral dislocation of the PIP joint.

MATERIALS AND METHODS

In group A, 25 patients were treated by closed reduction and immobilisation with a short-arm cast including both interphalangeal joints for 4 weeks. In group B, 25 patients were treated by dorsal block splinting of the PIP joint following reduction. The finger was released in extension with daily active exercise of the PIP joint.

RESULTS

In group A, 9 patients showed a normal range of motion, whereas a limitation of extension of 10 deg and more was seen in 16 patients. All PIP joints were clinically stable, and 19 patients were satisfied. Two patients complained of a limitation of extension, 3 of limitation of extension and pain, and 1 of pain and swelling. In group B, only 2 of 25 patients showed a limitation of extension of 10 deg and more, whereas 23 patients showed a normal range of motion. Instability of one collateral ligament was seen in 2 cases. Palmar instability did not occur, and 18 patients were satisfied. One patient complained of instability, pain and lack of extension during hard work, 1 of pain in combination with instability, 2 of pain and 3 of swelling of the joint.

CONCLUSION

Early active motion after dorsolateral dislocation of the PIP joint produces significantly superior results regarding the active range of motion and pinch power than static splinting.

Scapholunate ligament reconstruction using a periosteal flap of the iliac crest: a biomechanical study

INTRODUCTION

Advances continue to improve direct reconstruction of the dorsal scapholunate (SL) ligament, which is the strongest part of the entire SL ligament and is known as the turning point between the scaphoid and lunate. This study was designed to compare the biomechanical properties of the dorsal SL ligament with those of a periosteal flap of the iliac crest, which is a new graft candidate for dorsal SL reconstruction.

MATERIALS AND METHODS

A bone-ligament-bone complex was harvested for biomechanical testing from the iliac crest and the dorsal SL complex. Ten specimens could be prepared in each group. After potting the bone blocks in methylmethacrylate for stable fixation, the specimens were tested, using a servohydraulic testing system, at a rate of 10 mm/min.

RESULTS

Failure displacement, failure force, failure stress, energy to failure, and stiffness were assessed for both groups. Eight specimens in each group were tested successfully. In the ligament group, six specimens failed at the ligament level, whereas two failed at the insertion of the scaphoid. In the periosteum group, all eight specimens failed at the ligament level. The failure force of the dorsal SL ligament averaged 171.8 N, failure stress was 10.3 N/mm2, and failure displacement amounted to 2.9 mm. Energy to failure was 269.1 N-mm, and stiffness averaged 77.2 N/mm. Failure force of the periosteal flap amounted to 144.3 N, failure stress was 9.9 N/mm2, failure displacement was 3.0 mm, and energy to failure was 217.9 N-mm. Stiffness of the periosteal flap measured 60.5 N/mm. Comparison of the dorsal SL ligament and the periosteal flap of the iliac crest revealed no significant biomechanical differences.

CONCLUSION

Therefore, the biomechanical properties of the periosteal flap recommend its use for reconstruction of the dorsal SL ligament.

Anatomical basis for functional treatment of dorsolateral dislocation of the proximal interphalangeal joint

Dorsolateral dislocation of the proximal interphalangeal (PIP) joint is a common injury to the hand. Closed reduction of the dislocation anatomically realigns the avulsed ligaments; thus patients may be managed non-operatively. Standard treatment involves placement of a dorsal splint to prevent hyperextension and lateral stresses. This allows early active motion of the PIP joint while preventing a flexion contracture. In this fresh cadaver study, the PIP joint in 24 fingers was dorsolaterally dislocated. Four digits had to be excluded from the investigation due to a fracture dislocation with a bony fragment of >40% of the articular surface of the middle phalanx. After closed reduction, seven digits were further studied using the cryosection technique described by Kathrein et al. (1996, Clin. Anat. 9:227-231) to demonstrate the position of the avulsed palmar plate. In another 13 joints, the torn ligaments were examined by gross dissection. In 10 degrees of finger flexion, the avulsed palmar plate lay at its previous attachment to the base of the middle phalanx. The collateral ligament, ruptured at its attachment to the side of the head of the proximal phalanx, returned to its original position and was not interposed in the joint. The split between the collateral ligament and the accessory collateral ligament was also closed. Our data suggest that the ligamentous structures of the PIP joint, namely the palmar plate and collateral ligaments, typically return to their anatomic positions upon simple closed reduction of dorsolateral dislocations in fresh cadavers.

Clinical Toxoplasma gondii, Hammondia heydorni, and Sarcocystis spp. infections in dogs

Concurrent infections with coccidians Toxoplasma gondii, Sarcocystis spp., and a Hammondia heydorni-like parasite were identified in tissues of three littermate pups on a Kelpie dog breeding farm in Australia. In total, 20 pups in four litters had died following vaccination with an attenuated distemper virus vaccine. Toxoplasma gondii tachyzoites were identified immunohistochemically in tissues of two dogs. Sarcocystis sp. sporocysts were seen in the intestinal lamina propria of two dogs. Asexual and sexual stages of H. heydorni-like parasite were found in enterocytes of the small intestine of two dogs. Ultrastructural development of schizonts and gamonts of this parasite is described. None of the protozoa in these dogs reacted with antibodies to Neospora caninum. Feeding of uncooked tissue of sheep was considered to be the likely source of infection for these coccidians in dogs.

Cardiomyopathy associated with angiomatous pheochromocytoma in a rhesus macaque (Macaca mulatta)

A 24-year-old female rhesus macaque (Macaca mulatta) presented with a clinical history of chronic heart disease and prolonged recovery from sedation and anesthesia. At necropsy, the heart was markedly enlarged, with thinned ventricular walls, dilated chambers, and severe left atrioventricular valvular insufficiency. The ventricular walls contained numerous narrow, pale, often coalescing streaks that often extended along vessels into the deeper myocardium. Histologically, bands of interstitial fibrosis in the heart were associated with areas of myofiber atrophy, myofibril degeneration and loss, and inflammation. The left adrenal gland contained a 2 x 1 x 0.5 cm tumor with an unusual angiomatous pattern consisting largely of blood-filled sinusoids lined by one to four layers of low cuboidal to polyhedral tumor cells. In most sinusoids, the tumor cells appeared to be in direct contact with blood, although endothelial cells lined some sinusoids. Ultrastructurally, the tumor cells contained abundant electron-dense cytoplasmic granules. These granules were argyrophilic by Sevier-Munger staining and intensely immunoreactive for synaptophysin, chromogranin A, neuron-specific enolase, and S-100. These findings helped confirm the diagnosis of angiomatous pheochromocytoma. The heart lesions match those reported for catecholamine cardiomyopathy in other species.

Structure of Sarcocystis neurona sarcocysts

The ultrastructure of Sarcocystis neurona sarcocysts was studied from muscle of an experimentally infected cat. The cat was killed 144 days after being fed sporocysts from a naturally infected opossum. Sarcocysts were microscopic, up to 700 microm long, and up to 50 microm wide. By light microscopy, the sarcocyst wall was 1-2 microm thick. Ultrastructurally, the sarcocyst wall consisted of numerous villar protrusions. The villar protrusions were up to 2.8 microm long and 0.4 microm wide, with a tapered end. Microtubules extended from the tip of the villus to the base and occasionally extended deep into the granular layer. The granular layer was approximately 0.5 microm thick. Longitudinally cut bradyzoites were 5.2 by 1.2 (4.8-6.5 by 1.0-1.3) microm in size. Micronemes in bradyzoites were numerous and located in the anterior 1/3 of the conoidal end.

Incidental recall on WAIS-R digit symbol discriminates Alzheimer's and Parkinson's diseases

The purpose of this study was to examine how Alzheimer's (n = 37) and Parkinson's (n = 21) patients perform on the incidental recall adaptation to the Digit Symbol of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and how such performance is related to established cognitive efficiency and memory measures. This adaptation requires the examinee to complete the entire subtest and then, without warning, to immediately recall the symbols associated with each number. Groups did not differ significantly on standard Digit Symbol administration (90 seconds), but on recall Parkinson's patients recalled significantly more symbols and symbol-number pairs than Alzheimer's patients. Using only the number of symbols recalled, discriminate function analysis correctly classified 76% of these patients. Correlations between age-corrected scaled score, symbols incidentally recalled, and established measures of cognitive efficiency and memory provided evidence of convergent and divergent validity. Age-corrected scaled scores were more consistently and strongly related to cognitive efficiency, whereas symbols recalled were more consistently and strongly related to memory measures. These findings suggest that the Digit Symbol recall adaptation is actually assessing memory and that it can be another useful way to detect memory impairment.

Diclazuril preventive therapy of gamma interferon knockout mice fed Sarcocystis neurona sporocysts

Gamma interferon knockout (KO) mice (n=74) were fed a lethal dose of approximately 1000 sporocysts of the SN15-OP isolate of Sarcocystis neurona. Groups of mice were given pelleted rodent feed containing 50ppm of diclazuril at different times before and after feeding sporocysts. All mice were examined at necropsy and their tissues were examined immunohistochemically for S. neurona infection. Twenty mice were fed sporocysts and given diclazuril starting 5 days before feeding sporocysts and continuing 30-39 days post-infection (p.i.). One mouse died of causes unrelated to S. neurona with no demonstrable parasites; the remaining 19 mice remained clinically normal and S. neurona organisms were not found in their tissues. Sarcocystis neurona organisms were not demonstrable by bioassay of the brains of these 19 mice in uninfected KO mice. Sarcocystis neurona organisms were not found in tissues of five mice treated with diclazuril, starting 7 days after feeding sporocysts and continuing up to 39 days p.i. Therapy was less efficient when diclazuril was given 10 days p.i. Sarcocystis neurona organisms were found in two of 19 mice treated with diclazuril starting 10 days after feeding sporocysts, in two of five mice starting therapy 12 days p.i., and in 10 of 10 mice when treatment was delayed until 15 days p.i. All 15 mice fed S. neurona, but not given diclazuril, developed neural sarcocystosis and were euthanized 22-30 days after feeding sporocysts. Six mice not fed S. neurona, but given diclazuril for 44 days, remained clinically normal. Results indicate that diclazuril can kill the early stages of S. neurona.

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

Fatal visceral and neural sarcocystosis in dogs

This paper describes acute visceral and neural sarcocystosis in four dogs. One animal was simultaneously infected with distemper virus, and another with Blastomyces dermatitidis. Schizonts and merozoites of Sarcocystis canis were found in the lesions. 1999 W.B. Saunders and Company Ltd.

Rapid postmortem invasion of cecal mucosa of macaques by nonpathogenic Entamoeba chattoni

Although Entamoeba histolytica is the third leading parasitic cause of death in the world, most infections in humans are asymptomatic and restricted to the intestinal lumen. Entamoeba histolytica infections have also been reported in most species of captive nonhuman primates, with New World monkeys being particularly susceptible to fatal invasive amebiasis. In contrast, Old World monkeys appear to be resistant to the disease, although tissue invasion in asymptomatic monkeys has been reported. Our initial objectives were to determine the incidence, the predisposing factors, and the light microscopic and ultrastructural features of invasive amebiasis in Macaca mulatta (rhesus) and and M. fasicularis (cynomolgus) macaques. Our findings indicate that nonpathogenic E. chattoni in macaques can invade cecal mucosa rapidly (within 1 hr) after death. Therefore, the presence of invasive Entamoeba trophozoites in routinely collected necropsy materials should be interpreted with caution, particularly in cases where tissue fixation is delayed.

Role of Shiga-like toxin I in bacterial enteritis: comparison between isogenic Escherichia coli strains induced in rabbits

BACKGROUND/AIMS

Enteroadherent Escherichia coli that produce Shiga-like toxins are important causes of human disease, including enterohemorrhagic E. coli-induced colitis (EHEC). The role of Shiga-like toxins in these illnesses is unclear. The aim of this study was to establish an animal model for human EHEC and to determine the role of Shiga-like toxin I (SLT-I) in this model.

METHODS

E. coli strain RDEC-1 is an enteroadherent rabbit diarrheal pathogen. An isogenic variant of RDEC-1 (termed RDEC-H19A) producing high levels of SLT-I was obtained by infecting RDEC-1 with an SLT-I-converting bacteriophage. The effects of in vivo enteric infection produced in rabbits by RDEC-H19A were compared with those in uninfected and RDEC-1-infected animals.

RESULTS

SLT-I-producing RDEC-H19A induced a severe, noninvasive, enteroadherent infection in rabbits. Clinically, infection with RDEC-H19A was more severe than infection with RDEC-1 and caused more serious histological lesions including vascular changes, edema, and more severe inflammation. Interleukin 1 and platelet-activating factor appear to be important inflammatory mediators to this infection.

CONCLUSIONS

The illness induced by RDEC-H19A in rabbits resembled enterohemorrhagic E. coli-induced colitis of humans. SLT-I is an important virulence factor in the pathogenesis of EHEC.

Etiology, incidence, and prevention of deep vein thrombosis in acute spinal cord injury

This article provides a critical review of the literature on the etiology, incidence, and prevention of deep-vein thrombosis in acute spinal cord injured patients. Stasis and hypercoagulability are the two major factors contributing to the development of thrombosis in this patient population. This has been supported by studies that demonstrate an impaired venous return from the lower extremities and abnormal coagulation factors, which predispose to thrombogenesis. The incidence of deep vein thrombosis secondary to the above etiologies varies from 49% to 100% in the first 12 weeks with the first 2 weeks having the highest rate following acute injury. This high rate of complication has led to numerous studies to identify the most effective regimens of prophylaxis. Studies using noninvasive testing and venography in acute spinal cord injury have supported two approaches for preventing deep-vein thrombosis. Single agent pharmacologic therapy with adjusted dose heparin is effective but does carry some risk of bleeding. Combination therapy with external pneumatic compression sleeves plus either aspirin/dipyridamole or low-dose heparin and electrical stimulation plus low-dose heparin have significantly reduced the incidence of deep vein thrombosis. The duration of prophylaxis with the above modalities has varied between 8 and 12 weeks following acute injury. Further large scale studies are required in this high-risk population to better delineate the incidence of deep vein thrombosis and pulmonary embolism, to identify the best modalities, and to define the duration of treatment for the prevention of these complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective measures of ocular irritation as a consequence of hydrogen sulphide exposure

Hydrogen sulphide (H2S) exposure has been reported to adversely affect the eyes. Objective information regarding the extent of injury relative to varied exposure concentrations of H2S has not been published. The exfoliative eye cytology procedure has been demonstrated to provide quantitative information regarding the degree of ocular irritation and to allow for comparisons to be made between the irritants. This paper evaluates this procedure's efficiency in determining the degree of ocular irritation resulting from hydrogen sulphide exposure in rats.