Angular-dependent I-V characteristics in borocarbide superconductor YNi(2)B(2)C.

We present angular-dependent current-voltage (I-V) measurements in borocarbide YNi(2)B(2)C single crystals near the vortex-glass irreversible line. External magnetic fields are applied along the angle θ with respect to the c-axis. The nonlinear I-V curves reveal scaling behaviour near the transition. Using the scaling analysis, the relevant critical exponents and vortex transition temperatures are determined for all orientations. The data agrees well with the vortex-glass (VG) model. No evidence was found that supports the existence of a Bose-glass (BG) type of transition.

Focal intracranial infections due to Propionibacterium acnes: report of three cases.

OBJECTIVE AND IMPORTANCE: Except for its role in shunt infections, Propionibacterium acnes has been of little interest to neurosurgeons. The rarity and indolent nature of focal intracranial infections by P. acnes limit their recognition. Three cases of serious intracranial infection due to this organism are described. CLINCAL PRESENTATION: Three patients with histories of immunosuppression and neurosurgical procedures developed nonspecific, delayed presentations (5 wk to 5 yr after surgery) of intracranial infections. In two patients, radiological investigations showed enhancing lesions that were later found to be brain abscesses. A subdural empyema was found in the third patient. INTERVENTION: All three patients underwent surgical drainage of the purulent collections. P. acnes was isolated in each case, and each patient was treated with a 6-week course of intravenous penicillin. All three patients made good recoveries, and subsequent imaging showed no recurrence of the infectious collections. CONCLUSION: P. acnes is an indolent organism that may rarely cause severe intracranial infections. This organism should be suspected when an intracranial purulent collection is discovered in a patient with a history of neurosurgical procedures. Immunosuppressed patients may be susceptible to this otherwise benign organism. Surgical drainage and treatment with intravenous penicillin should be considered standard therapy.

Outcomes after aneurysm rupture during endovascular coil embolization.

OBJECTIVE: Intracranial aneurysm rupture during placement of Guglielmi detachable coils has been reported, but the management and consequences of this event have not been extensively described. We present our experience with this feared complication and report possible neuroradiological and neurosurgical interventions to improve outcomes. METHODS: We retrospectively reviewed the records for 701 patients with 734 intracranial aneurysms that were treated with endovascular coiling, during a 6-year period, in the metropolitan Minneapolis-St. Paul (Minnesota) area. This analysis revealed 10 cases of perforation during coiling. The management and outcomes were recorded, and the pertinent literature was reviewed. RESULTS: All 10 cases involved previously ruptured aneurysms. This complication occurred sporadically and was not observed in the first 100 cases. Perforation occurred during microcatheterization of the aneurysm in two cases and during coil deposition in eight cases. Seven of the perforated aneurysms were located in the anterior circulation and three in the posterior circulation. Six of the 10 patients made good or fair recoveries; all three patients with posterior circulation lesions died immediately after rehemorrhage. Elevated intracranial pressure (ICP) was noted for all five patients with intraventricular catheters in place. Bilateral pupil dilation and profound hemodynamic changes were noted for eight patients. Coiling was rapidly completed, and total or nearly total occlusion was achieved in all cases. Emergency ventriculostomy was performed to rapidly reduce increased ICP for two patients, both of whom made good recoveries. Hemodynamic and angiographic factors after perforation, such as prolonged systemic hypertension, persistent dye extravasation after deployment of the first Guglielmi detachable coil, and persistent prolongation of contrast dye transit time (suggesting ongoing ICP elevation), were correlated with poor outcomes. CONCLUSION: Previously ruptured aneurysms seem to be more susceptible to endovascular treatment-related perforation than are unruptured lesions. Worse prognoses are associated with iatrogenic rupture during coiling of posterior circulation lesions, compared with those in the anterior circulation. When perforation is recognized, the definitive treatment seems to be reversal of anticoagulation therapy and completion of Guglielmi detachable coil embolization. Immediate neurosurgical intervention is limited in these cases and focuses on decreasing ICP via emergency ventriculostomy. However, these measures may be life-saving, and neurosurgical assistance must be readily available during treatment of these cases.

Stimulation of smooth muscle cell proliferation by ox-LDL- and acetyl LDL-induced macrophage-derived foam cells.

To test the hypothesis that LDL lacking of initial oxidation may also anticipate an essential role in the progression for atherosclerotic lesions, we studied the in vitro effect of foam cells induced by low density lipoprotein (LDL), oxidized (ox)-LDL or acetyl-LDL on smooth muscle cell (SMC) proliferation. Intraperitoneal macrophages collected from ICR mice were incubated with buffered saline LDL, ox-LDL or acetyl-LDL to induce foam cell formation. Porcine aortas with atherosclerotic lesions were collected from 5 pigs fed high cholesterol diets. The results indicate that foam cells induced by ox-LDL and acetyl-LDL, but not by LDL, promoted SMC proliferation. SMC proliferation was also increased by ruptured, ox-LDL- and acetyl-LDL- induced foam cells. Immunohistochemically, epitopes of the LDL, ox-LDL, and malondialdelyde (MDA)-LDL were present in atherosclerotic lesions, but the acetyl epitope was not. We suggest that foam cells, whether induced by the oxidized or acetyl or acetyl (unoxidized) form, play an essential role in the pathogenesis of atherosclerosis by stimulating SMC proliferation.

An improved system for quantifying AgNOR and PCNA in canine tumors.

BACKGROUND: Quantifying silver stained nucleolar organizer regions (AgNORs) and proliferation cell nuclear antigens (PCNA) are useful techniques to measure proliferative activity of tumor cells; however, the nonspecific deposition of stains and overlappings of AgNOR and PCNA counts between grades of tumors hamper their applications. MATERIALS AND METHODS: Fifty-two surgical specimens from dogs, including mast cell tumors, perianal gland tumors and hyperplasias, fibromas, fibrosarcomas, and normal tissues were studied. The 3 microns dewaxed sections of formalin-fixed tissues were stained to detect AgNORs by a modified inverted incubation technique in a newly developed silver staining device. Data were collected and analyzed using a high-resolution digital microscope camera and image analysis software. Sequential sections were also stained for PCNA using an immunohistochemical method. RESULTS: The improved system for quantifying AgNOR provided more accurate and non-overlapping mean AgNOR counts, which enable us to distinguish benign states from malignant changes. The mean AgNOR cut-off points that discriminated grade II or III mast cell tumors from grade I, perianal gland carcinomas from adenomas (or hyperplasia), fibrosarcomas from non-fibrosarcoma tissues, were 6.0, 14.1, 9.4, and 8.8 respectively. The mean AgNOR areas, relative AgNOR areas, and PCNA positive rates of some malignant and non-malignant tissues (benign tumor and normal tissues) were significantly different (P < 0.05). CONCLUSIONS: This improved system is a sensitive and rather precise method for quantifying the AgNOR and PCNA. It provides a valuable objective measurement for differentiating benign and malignant tumors.

Proliferation characteristics of canine transmissible venereal tumor.

Canine transmissible venereal tumor (CTVT) grows progressively (P-phase) in the host and then spontaneously regresses (R-phase). The mechanisms behind the transition from the P-to R-phases are not well understood. In this study, in order to determine the proliferation characteristics of CTVT, we evaluated telomerase activity and enumerated nuclear organizing regions (AgNOR) and proliferating cell nuclear antigen (PCNA). It was found that CTVT cells from the P-and R-phases were both positive for telomerase activity, although it was lower in the R-phase. Evaluations of telomerase activity should take into account the stage of mitosis. Although, in the majority of cases, telomerase activity can be used to differentiate between benign and malignant tumors in dogs, other factors or markers should also be used to obtain accurate diagnoses. The PCNA-positive rate and the number and area of AgNOR per cell increased much more in the P-phase than the R-phase. However, the AgNOR values were always higher. Thus, the AgNOR count can be used to distinguish the P-and R-phases of CTVT. In addition, mitotic figures were much higher in number in the P-phase as compared to the R-phase. We believe that, during spontaneous regression of CTVT cells, slow tumor cell proliferation must contribute to the decrease in tumor size. However, shortening of tumor cell telomeres is not directly involved in this process. Other factors, such as expression of MHC antigens on CTVT cells, humoral immunity, cytokines released by the inflammatory cells and, especially, tumor infiltrating lymphocytes may contribute to CTVT regression.

Morphological and functional comparisons of Peyer's patches in different parts of the swine small intestine.

Fifteen conventional 8-week-old pigs were used to compare the morphology and function of Peyer's patches (PP) in different parts of the small intestine with special emphasis on the dome epithelium (DE). The comparisons were done by morphological observation through light and electron microscopy, and by the ability of the DE complex to phagocytize horseradish peroxidase (HRP). Dome epithelium of the PP in the jejunum was more superficially located in the mucosa in comparison with the ileum. The DE's of the ileum were much smaller, with an area of 3.7 micron2/DE, than that of the jejunum (18.4 micron2/DE). The number of DE areas/5 cm2 in the ileum was more than in the jejunum. However, the total surface area of DE/5 cm2 of PP, was larger in the jejunum (180.5 micron2) than in the ileum (55.6 micron2). Brown discoloration of diaminobenzidine-hydrogenperoxide (DAB+H2O2)-treated PP specimens, after HRP inoculation, intensified with post-inoculation time from 20 s to 5 min. The brown pigment first appeared on the surface of microvilli and infiltrated into the dome. No morphological differences were observed between the jejunum and the ileum in 1 micron thick Epon-embedded specimens. Intramucosally, brown pigment was almost always found in DE areas. The pigmented areas were more numerous in the jejunum but the color intensity showed no obvious difference. By transmission electron microscopy, the electron dense materials (which were interpreted as the products of HRP and DAB+H2O2) were found between the microvilli of membraneous (M) cells, in the intercellular spaces of the DE, and in a form similar to intracytoplasmic vesicles in the cytoplasm of M-cell and DE complex lymphocytes. Our results confirmed that DE of PP had much stronger phagocytic activity than did the ordinary villous epithelium. This evidence indicates that the DE complex of PP in the swine intestine is immunologically important.

Morphologic studies of intrapulmonary airway mucosa-associated lymphoid tissues in swine.

Morphologic structures of the lymphoid tissues associated with the mucosa of the respiratory tract in swine aged 11 to 13 weeks were studied by dissecting, light, and transmission electron microscopy. Tissues along the respiratory tract were collected for further examination. Light microscopic examination showed that the lymphoid tissues were associated with bronchi (8.38%), bronchioles (81.63%), and respiratory bronchioles (9.98%). The lymphoid tissues were identified at different levels of the airways and were designated intrapulmonary airway mucosa-associated lymphoid tissues. Anatomically, the lymphoid tissues were found mostly in the bronchiolar bifurcations, with an arteriole frequently nearby. Histologically, the lymphoid tissues contained a single dome-shaped lymphoid follicle, which bulged out from the mucosal surface into the airway, where it was covered along the mucosal side by a layer of specialized epithelium. Ultrastructurally, the mucosal surface of the specialized epithelial cells was equipped with microfolds or cytoplasmic projections instead of cilia. The cytoplasm was elongated, and therefore much thinner than that of ordinary epithelial cells. Many lymphocytes were found scattered in the mucosal epithelium between or beneath the specialized epithelial cells. This structure was similar to that seen in the Peyer's patches of the small intestine in swine and other animals.

Heat shock proteins in canine transmissible venereal tumor.

SDS-PAGE, Western blot analysis and immunohistochemical staining were used to detect heat shock proteins (HSPs) 60, 70 and 90 in canine transmissible venereal tumor (CTVT). Tissues tested for HSPs included: (1) tissues from different growth phases of CTVT tumors artificially induced in dogs; (2) tissues from other canine tumors; (3) normal dog tissues. Our results indicate that HSP 60 was consistently higher in CTVT cells in regressing phase than those in progressing phase. However, no detectable antibody response specific to the tested HSPs was found in the sera from CTVT-laden dogs in different growth phases. Although levels of the HSPs were all detectable in CTVT cells, only 60 and 70 were higher in CTVT cells than in normal tissues. In addition, none of the HSPs were detected in cells from five other canine tumors. These data suggest that canine HSP 60 and 70 are potential markers for CTVT and HSP 60 is appear to be involved in CTVT regression.PCR was used to confirm the existence of CTVT cells using primers designed to cover the sequence between the 5' end of c-myc near the first exon and the 3' end outside the LINE gene. Only CTVT samples were positive for this sequence; samples from other tumors and normal tissues were negative. The sequenced PCR products indicated that CTVT from Taiwan and other countries exhibited over 98% sequence homology. This reconfirms that, worldwide, all CTVT cells are very similar.

Workshop studies on monoclonal antibodies reactive against porcine myeloid cells.

Investigators from eight laboratories analyzed the reactivity of 22 monoclonal antibodies (mAb) against porcine myeloid cells. Based on binding data, clustering analysis and inhibition studies, workshop mAb 74-22-15 (003) and 6F3 (007) were assigned a swine workshop cluster number 3 (SWC3). These mAb recognized macrophages and neutrophils; neutrophils; a monocyte/macrophage-specific mAb was not identified by this workshop.

Overview of the Second International Workshop to define swine cluster of differentiation (CD) antigens.

The aim of the Second International Swine Cluster of Differentiation (CD) Workshop, supported by the Veterinary Immunology Committee (VIC) of the International Union of Immunological Societies (IUIS), was to standardize the assignment of monoclonal antibodies (mAb) reactive with porcine leukocyte differentiation antigens and to define new antibody clusters. At the summary meeting of the workshop in July, 1995, revisions in the existing nomenclature for Swine CD were approved, so that the rules are now in accord with those for human and ruminant CD. Swine CD numbers will now be given to clusters of mAb to swine orthologues of human CD molecules when homology is proven by (1) suitable tissue distribution and lymphoid cell subset expression, (2) appropriate molecular mass of the antigen recognized by the mAbs, and (3) reactivity of mAbs with the cloned swine gene products, or cross-reactivity of the mAb on the human gene products. In some cases, this reactivity would not be fully proven, mainly due to the lack of cloned gene products; for these CD antigens, the respective clusters will be assigned by the prefix 'w' which will lead to 'wCD' antigens. As a result of the Second International Swine CD Workshop the assignment of 16 mAb to existing CD groups (CD2a, CD4a, CD5a, wCD6, wCD8, CD14, CD18a, wCD21, wCD25) was confirmed, and 2 mAb to existing swine workshop clusters (SWC). More importantly, for the work on the porcine immune system, was the definition of 5 new swine CD antigens, namely CD3 (recognized by 6 new mAb and 3 epitopes), CD16 (1 new mAb), wCD29 (2 mAb), CD45RA (3 mAb) and CD45RC (1 new mAb). Finally, the demarcation of two new SWC molecules in swine, SWC8 (2 mAb) and SWC9 (2 mAb) was confirmed.

Optimizing brain tumor resection. High-field interventional MR imaging.

High-field strength iMRI guidance is an effective tool for brain tumor resection. Although its use lengthens the average time for a craniotomy, the reward is a more extensive tumor excision compared with conventional neurosurgery without an increased risk to the patient (Table 4). Although intraoperative patient transfer into and out of the magnet is cumbersome, the possibility for complete resection, especially for a low-grade glioma, makes the effort worthwhile. The cost and technical support required for this system presently limits its use to only a few sites worldwide. As with any technology, further refinements will make this system less expensive and more attainable. Practical consideration aside, high-field strength iMRI is presently [table: see text] the most effective tool available for brain tumor resection. Because of its novelty, future studies are necessary to determine if this technology lowers the incidence of and extends the duration to tumor recurrence as the preliminary data in children suggests. These are the ultimate measures of efficacy for any brain tumor treatment. Based on the rapid advancement of technology, will today's high-field strength interventional magnet become tomorrow's low-field system? Very high-field strength designs may improve diagnostic capabilities through higher resolution, but their interventional applications may be hindered by increased sensitivity for clinically insignificant abnormalities and decreased specificity for clinically relevant lesions. As new technology is developed, clinicians must continue to explore and refine the existing high-field strength iMRI to make it cost-effective and widely applicable.

Minimally invasive procedures. Interventional MR image-guided functional neurosurgery.

Intraoperative MR imaging techniques have the potential to greatly improve the stereotactic methods used for functional neurosurgery. No longer are neurosurgeons and patients always constrained by uncomfortable head frames and conventional stereotaxy. Accuracy and complication avoidance are improved by intraoperative imaging. Safety of operative machinery and equipment in an MR imaging operative suite is attainable, even with deep brain stimulating electrodes in depth electrodes for epilepsy. Although cost-effectiveness remains to be determined (see article by Kucharczyk et al in this issue), the minor inconveniences of operating within an iMRI environment seem to be significantly outweighed by the benefits.

An acute pleuropneumonia in a pig caused by Chromobacterium violaceum.

A 2.5-month-old, 30 kg Duroc pig died 10 days after showing clinical signs of dyspnoea and diarrhoea. Acute necrotizing and fibrinous pleuropneumonia with locally extensive lesions was found. Chromobacterium violaceum was isolated from pneumonic lung tissues and intratracheal inoculation of a pure culture into two SPF pigs reproduced lesions similar to those found in the natural infection.

Granular mucosal lymphocytes in porcine small intestine.

A subpopulation of purified, interepithelial lymphocytes from porcine small intestinal mucosa contained cytoplasmic granules. Toluidine blue staining revealed metachromatic granules in 13.64% (606/4,450) cells. The cells had scant organelles, a single large nucleus with obvious invagination of the nuclear membrane, and prominent chromatin. Each cell contained 1 to 10 cytoplasmic membrane-bound granules, 0.6 to 1.5 micron in diameter. These findings indicated that the granular mucosal lymphocytes are related morphologically to mucosal mast cells. The presence of serotonin in the granules, confirmed by the serotonin releasing test, provided functional evidence that granular mucosal lymphocytes are related to mucosal mast cells.

Changes in gut-associated lymphoid tissues of the small intestine of eight-week-old pigs infected with transmissible gastroenteritis virus.

The responses of the interepithelial lymphocytes (IEL) and aggregated lymph nodules (ALN; Peyer's patches) of the small intestines of 8-week-old pigs to transmissible gastroenteritis virus (TGEV) infection were characterized at 12, 18, and 24 hours after pigs were inoculated. There was no significant difference in numbers of IEL between control and TGEV-infected pigs at 12 and 18 hours. However, in pigs examined at 24 hours, there was a significant decrease in the number of IEL in the duodenum and cranial portion of the jejunum and an increase of IEL numbers in the nuclear level of the intestinal epithelium. Number and distribution were unchanged in the middle portion of the jejunum and the ileum. Microscopic changes in TGEV-infected pigs included microulceration of the dome epithelium (DE) over the ALN, especially in the cranial portion of the intestine, and villous atrophy in the entire length of the small intestine. Generally, TGEV was found by means of peroxidase-antiperoxidase staining in areas where microscopic lesions occurred. Electron microscopy revealed that M cells and ordinary microvillus-covered epithelial cells in the DE embraced one or more lymphocytes, and formed a specialized cell complex or DE complex. Most of the lymphocytes in the DE complex possessed many organelles indicative of an active cell state. The TGEV was found between microvilli, in the cytoplasmic vesicles of M cells and microvillus-covered epithelial cells in the DE, and in the cytoplasm of macrophages and lymphocytes and some degenerated cells of unidentified origin in the domes of the ALN. The virus was also commonly found in cytoplasmic vesicles of macrophages and degenerated cells in the intestinal lumen near the base of the dome of the ALN.

Isolation and characterization of porcine milk lactoferrin.

We purified porcine whey lactoferrin by affinity chromatography on a heparin-Sepharose column, followed by high-performance liquid chromatography. Molecular mass of purified lactoferrin (PLF) is 78,000 daltons. The iron-binding activity of PLF had a UV/visible-light absorption spectrum indistinguishable from that of human and bovine lactoferrins (absorbance ratio [465 nm/280 nm] approx 0.046). The growth ratio of WIL-2 cells in PLF-supplemented medium is 70% of that in serum-containing medium. The aforementioned characteristics are similar to those of human and bovine lactoferrins. Immunoblot analysis, using polyclonal antibody raised in rabbits against porcine whey lactoferrin, revealed high specificity for PLF, and low cross-reactivity with commercial human and bovine lactoferrins.

Applications of peroxidase-antiperoxidase staining technique for detection of transmissible gastroenteritis virus in pigs.

The peroxidase-antiperoxidase (PAP) staining technique was used for the detection of transmissible gastroenteritis virus (TGEV) in small intestines of TGEV-infected 8-week-old pigs and in infected McClurkin pig testicle cells by means of light microscopy. The specific-positive reaction was characterized by the presence of many brown granules of various sizes in the cytoplasm of infected cells. Nonspecific granules caused by endogenous peroxidases in the cytoplasm of eosinophils stained by PAP were darker, larger, more round, and more uniform in size than were specific granules. Acetone fixation was superior to fixation with periodate-lysine-paraformaldehyde or 10% formalin. Our results indicate that the PAP staining technique is a sensitive, specific technique for detection of TGEV in the small intestines of pigs.

Placental lesions caused by pseudorabies virus in pregnant sows.

Pathologic and viral investigations were done on 13 fetal placentas and 23 aborted fetuses associated with naturally occurring pseudorabies in swine. Of the 13 fetal placentas examined, 7 (53.8%) had various degrees of necrotizing placentitis. The lesions were characterized by coagulative necrosis of the chorionic fossae and by intranuclear inclusions in degenerating trophoblasts and occasionally in mesenchymal cells. In addition, a mild inflammatory cell reaction was observed in the mesenchyma. Numerous viral particles, ultrastructurally indistinguishable from herpesvirus, were observed by electron microscopy in the affected chorionic membrane. Large aggregates of herpesvirus virions were demonstrated in the nucleus and cytoplasm of degenerated trophoblasts and mesenchymal cells. Of the 23 aborted fetuses examined, 22 (95.6%) had typical coagulative necrosis in the liver, spleen, adrenal glands, and visceral lymph nodes. Inclusions similar to those in the chorionic placenta were observed in the parenchymal cells of those organs, on the margins of necrotic areas. Pseudorabies virus was isolated from various organs of the aborted fetuses, but virus isolation from the placentas was not attempted. In a survey of 52 affected sows, sera from 49 (94.2%) neutralized the isolated virus. The findings indicated that the placental lesions caused by the virus were primary. The study also indicated the merit of routine examination of aborted fetal placentas and fetuses for diagnosis of pseudorabies.

Epidemiological characteristics and financial costs of the 1997 foot-and-mouth disease epidemic in Taiwan.

Between March and July 1997, a devastating outbreak of foot-and-mouth disease (FMD), serotype O, occurred in pigs in Taiwan. A total of 6,147 pig farms with more than 4 million pigs were infected, and 37.7 per cent of the pigs in Taiwan either died (0.18 million pigs) or were killed (3.85 million pigs). The epidemic reached its peak during the fifth week after it was first recognised. During the eighth and ninth weeks, a two-dose blanket vaccination programme was instituted which led to a large reduction in new outbreaks. Except for two cities, the whole of Taiwan was declared an FMD-infected zone. During the four months in which new farm outbreaks occurred, 21.7 per cent of the pigs on infected farms showed clinical signs, and there was an overall mortality of 3.95 per cent. During the early stages of the epidemic, the incubation period was as short as 24 hours and the case fatality rates for suckling piglets reached 100 per cent. The financial cost of the epidemic was estimated at US$ 378.6 million, including indemnities, vaccines, carcase disposal plus environmental protection, miscellaneous expenses, and loss of market value. Owing to the ban on exports of pork to Japan, it is estimated that the total economic cost to Taiwan's pig industry will be about US$ 1.6 billion.