Deficits in radial-arm maze learning in aged rats

The present study was designed to investigate the possible deficits in the place learning on the 8-arm radial maze in aged rats. In this task, reward was given in the 4 predetermined arms. Aged rats (27 months old, N = 7) acquired this task more slowly than young rats (12 months old, N = 11), and didn't reach to the performance level of the young rats within 80 training trials. Analysis of error choices revealed that the aged animals first entered in the unbaited arms more often than the young rats, whereas there was no difference in the number of re-entered choices to the baited and unbaited arms between the aged and young animals. Therefore, it was concluded that learning deficits in aged rats were attributed to deficits in the reference memory but not in the working memory.     

High Frequency of Antibiotic-Associated Diarrhea due to Toxin A-Negative, Toxin B-Positive Clostridium difficile in a Hospital in Japan and Risk Factors for Infection

Patients hospitalized in a hospital with a high incidence of antibiotic-associated diarrhea due to toxin A-negative, toxin B-positive (A–/B+) Clostridium difficile were retrospectively investigated to determine the clinical manifestations and risk factors for infection. Of 77 Clostridium difficile isolates obtained from 77 patients during the 1-year investigation period, 30 were A–/B+ and 47 were toxin A-positive, toxin B-positive (A+/B+). By pulsed-field gel electrophoresis analysis, 23 of the 30 A–/B+ strains were outbreak-related, suggesting nosocomial spread of a single type of bacterium, which mainly affected patients in the wards of respiratory medicine, hematology and neurology. Using regression analysis, three factors were found to be associated with infection by A–/B+ isolates: (i) exposure to antineoplastic agents (P=0.01, odds ratio [OR]=5.1), (ii) the use of nasal feeding tubes (P=0.008, OR=5.2), and (iii) assignment to a certain internal medicine ward (P=0.05, OR=3.0). Between patients with Clostridium difficile-associated diarrhea caused by A–/B+ strains and those with A+/B+ strains, no statistically significant difference was found in body temperature, serum concentration of C-reactive protein, leukocyte count in whole blood, frequency of diarrhea, or type of underlying disease. These results indicate that A–/B+ strains of Clostridium difficile can cause intestinal infection in humans and they spread nosocomially in the same manner as A+/B+ strains.     

Histological evidence of the altered distribution of osteocytes and bone matrix synthesis in klotho-deficient mice

Mice homozygous for klotho gene deletion are well established aging models as they mimic certain aspects of human senescence e.g. osteoporosis. Induced senescence may affect cellular functions and alter the histological properties of the extracellular matrices. The present study examined the histological and ultrastructural features of osteocytes and the surrounding bone matrix in klotho-deficient mice. As expected, osteoblasts showed a flattened shape with a weak immunoreactivity for alkaline phosphatase, and the bone matrix contained many empty osteocytic lacunae. The walls of both normal and empty lacunae were intensely immunopositive for osteopontin and dentin matrix protein-1, but featured an inconsistent immunoreactivity for osteocalcin and type I collagen. Not surprisingly, TUNEL-positivity, indicative of apoptosis, was found in many osteoblasts, osteocytes, and bone marrow cells of the klotho-deficient mice. In transmission electron microscopy, an amorphous matrix containing non-collagenous organic materials was recognizable around osteoblasts and in the osteocytic lacunae. Some osteoblasts on the bone surface featured these amorphous materials in vacuoles associated with their trans-Golgi network, indicating that, under klotho-deficient conditions, they synthesize and secrete the non-collagenous structures. Some osteocytes displayed pyknosis or degenerative traits. Thus, our findings provide histological evidence that klotho gene deletion influences the spatial distribution of osteocytes and the synthesis of bone matrix proteins in addition to the accelerated aging of bone cells.     

CT myelography with intramedullary enhancement in cervical spondylosis

The authors describe seven cases of cervical spondylosis in which small high-density areas were detected in the spinal cord on delayed computerized tomographic (CT) myelography. These high-density areas are believed to represent cavities or areas of cystic necrosis. In all seven cases the cervical spinal canal was narrow, and the spondylosis was located at multiple levels, causing a so-called "pincer effect." On the CT scans the high-density areas resembled fried eggs in the gray matter. These areas were localized near the abnormal cervical discs. In two cases in which the Brown-Séquard syndrome was noted, the symptoms could be attributed to the morphology of the high-density area on the affected side of the cord. Following decompressive surgery, most of the symptoms improved except for numbness of the upper extremities and motor weakness of hands.     

Hypoxia-ischemic insult in neonatal rats induced slowly progressive brain damage related to memory impairment

The present study was designed to determine potential associations between the brain damage induced by hypoxic-ischemic (HI) insult and spatial learning impairment in an eight-arm radial maze task. We first determined the pathological outcomes after 2, 5, 9, and 17 weeks of recovery following the HI insult. The results show that the brain damage progressed from 2 up to 17 weeks of recovery. To clarify the time course of the brain damage changes, we investigated the histological changes of the same individual with magnetic resonance imaging (MRI) after 5, 9, and 57 weeks of recovery following the HI insult. The MRI changes were similar to the histological changes, and the brain damages were exacerbated in the contralateral hemisphere after 57 weeks of recovery following the HI insult. To investigate whether alteration in brain function was correlated with MRI and histological changes, the rats were made to find their way through an eight-arm radial maze was performed at either 7th or 16th weeks of recovery. According to the results, the spatial learning impairments of rats in the maze starting at 16 weeks of recovery were more severe than those at 7 weeks of recovery, indicating that the impairments were progressive and depended on the degree of brain damage. The results of the present study are the first demonstration that the evolutional and specific brain damage following the HI insult is slowly and progressively exacerbated to the contralateral hemisphere and rats who experience the HI are at risk for showing a late impairment of brain function.     

Neuroectodermal tumor of bone. Evidence for neural differentiation in a cultured cell line

A new cell line was established from a "neuroectodermal tumor of bone" affecting the right scapula of an 18-year-old man. The original neoplasm had dense proliferation of small round cells with abundant glycogen content and numerous Homer-Wright rosettes. The culture showed proliferation of small spindle cells with uniform oval nuclei and slender cytoplasmic processes. When the culture reached maximum density, rosette-like structures similar to those in the original tumor were formed. Under the influence of N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphoric acid (dibutyryl cAMP), the cultured cells expressed these rosette-like structures even in the lower cell concentration. Electron microscopy revealed that the cultured cells treated with dibutyryl cAMP contained high-density granules, well-developed microtubules, and abundant 10-nm filaments. By immunocytochemistry, neuron-specific enolase (NSE), and N-myc oncogene product were detected in the cultured cells as well as the original tumor. These results indicated the neuroectodermal origin of some of the small round cell tumors of bone.     

A rapid method for detecting barbiturates in serum using EI-SIM

A simple and rapid method for analysis of barbiturates in serum has been developed. In order to extract and clean barbiturates in serum, a separation column packed with Extrelut and Florisil was used, and the eluate was directly analyzed by means of electron impact selected ion monitoring (EI-SIM). Selected ions used were base peak ions of 10 barbituartes, and the internal standard used was allobarbital or secobarbital. The calibration curves were linear over the range 0.5–5 ng. Extraction of replicate serum samples containing 20 g/1.5 ml and 5 g/1.5 ml resulted in a recovery of 87.2–105.2% and 81.6–104.6%, respectively, with the exception of phenobarbital, which was 151.9% and 172.1%, respectively. Secobarbital was also analyzed in the serum of 13 patients who had been given secobarbital intravenously. In 3 out of 10 cases, Secobarbital levels greater than 1 g/ml were detected more than 72 h after administration. This method seems to have possibilities for clinical use.Paper presented at the 2nd International Symposium ADVANCES IN LEGAL MEDICINE, Berlin, Germany, August 30–September 1, 1993