Localization of Function Within the Dorsal Hippocampus: The Role of the CA3 Subregion in Paired-Associate Learning.

Computational models and electrophysiological data suggest that the CA3 subregion of the hippocampus supports the formation of arbitrary associations; however, no behavioral studies have been conducted to test this hypothesis. Rats with neurotoxin-induced lesions of dorsal dentate gyrus (DG), CA3, or CA1 were tested on object-place and odor-place paired-associate tasks to test whether the mechanism that supports paired-associate learning is localized to the CA3 subregion of the dorsal hippocampus or whether all hippocampal subregions contribute to paired-associate learning. The data indicate that rats with DG or CA1 lesions learned the tasks as well as controls; however, CA3-lesioned rats were impaired in learning the tasks. Thus, the CA3 subregion of the dorsal hippocampus contains a mechanism to support paired-associate learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

WAIS-R Information subtest item bias for Canadian high school students.

The WAIS-R Information subtest was combined with 21 potential substitute Canadian content items and group-administered to 119 high school students ranging in age from 16 to 19 years. Seven acceptable substitute items were identified. Mean scores on the American items for the 16-17 and 18-19 age groups suggested that Canadians of these ages are not penalized by American content with respect to either Verbal or Full Scale IQ. Nevertheless, the research identified eight Information items, four easier and four more difficult than the standard WAIS-R implies. Similar results were noted in two previous studies of the WAIS-R, and indicate the extreme caution required for the clinical interpretation of intra test scatter. There is also evidence that item difficulty within the Information subtest may vary with the age of the subject. These results were considered indicative of the necessity for Canadian content Information items and the development of Canadian norms for an adapted WAIS-R Information subtest. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Change of foot size with weightbearing. A study of 2829 children 3 to 18 years of age

The change of foot length and width with age has been reported in a few anthropometric studies in the literature. However, the relationship with body height rarely is reported, and the dynamic effect of weightbearing on foot size has not been documented. In this series, 2829 children 3 to 18 years of age of equal gender distribution were included in the study. The foot length and width on weightbearing and nonweightbearing were measured with a special precision electronic caliper. The foot length and width were found to increase linearly from the age of 3 years until 12 years in girls and 15 years in boys. This was followed by a phase during which the increase plateaued. The foot length and width increased significantly on weightbearing at all ages in both genders with a mean of 2.1 to 4.4 mm or 3.1% to 4.8%, respectively. The foot length and width also were found to correlate significantly with the body height in both genders, with a correlation coefficient of 0.96 to 0.98. No significant differences were found between the sizes of the dominant and nondominant foot in either gender.     

OFDM/FM frame synchronization for mobile radio data communication

A synchronization scheme enabling the use of orthogonal frequency division multiplexing (OFDM)/FM over a mobile radio channel in a pure ALOHA environment is proposed. The scheme encodes synchronization information in parallel with data in the same manner in which data is encoded in the OFDM/FM frame. The synchronization information is in the form of tones, centered in certain reserved frequency subchannels of the OFDM signal. The receiver uses a correlation detector, implemented in the frequency domain, to acquire synchronization accurately on a packet-by-packet basis. Experimental results indicate that the bit-error-rate performance achievable with the proposed scheme is within 1.5 dB of the performance obtained with ideal synchronization     

Occlusion of large atrial septal defects with a centering buttoned device: early clinical experience

A feasibility clinical study was conducted for the transcatheter occlusion of large ostium secundum atrial septal defects with the centering buttoned device. The centering buttoned device is a modification of the regular buttoned device in which a centering counter-occluder is sutured at the central 40% portion of the occluder. During centering it is stretched, forming a parachute-shaped structure and pulling the occluder over the center of the defect. During buttoning, the counter-occluder forms a double figure eight, opposing the right atrial side of the atrial septum. Occlusion was performed in 12 patients aged 6 to 56 years. All had been rejected for transcatheter occlusion by the regular buttoned device, because of either their defect size or the lack of adequate septal rim. The defect size varied between 23 and 31 mm, and the device size varied between 45 and 60 mm. Nine had immediate effective occlusions of their defects and three residual shunts. One patient with unbuttoning had hemolysis at 2 weeks and underwent surgery. Early results of the transcatheter occlusion of large atrial septal defects are promising, and larger clinical trials are justified.     

Epithelial cell hyperproliferation induced in the exocrine pancreas of mice by a western-style diet

BACKGROUND: Pancreatic cancer is a common cause of mortality in the United States, with an estimated 27,800 people dying of the disease in this country in 1996. Epidemiologic studies have suggested that Western diets containing high fat, high protein, and low calcium contents are associated with increased incidence of pancreatic cancer. PURPOSE: We investigated whether a Western-style diet containing increased fat content and decreased calcium and vitamin D contents would induce epithelial cell hyperproliferation (excess cell duplication) or hyperplasia (excess cell accumulation) in the pancreas, as was previously demonstrated in the colon and mammary gland. METHODS: C57BL/6J mice at 4 weeks of age were randomly assigned to one of two groups of 14 mice each. One group received the control diet ad libitum, and the other group was given the Western-style diet ad libitum. After 6, 9, and 15 weeks on the diet, four or five mice per group were infused with 5-bromo-2'-deoxyuridine (BrdU) for 72 hours by use of subcutaneously implanted Alzet osmotic pumps. The mice were then killed, and the pancreas of each mouse was removed. In the exocrine pancreas with ductal secretion, the duct system (including interlobular and intralobular ducts and centroacinar [i.e., centroductular] cells) and acini were measured both histopathologically and immunohistochemically (BrdU) and were analyzed without knowledge of the source of the specimens. Two-way analysis of variance was carried out. All P values were generated from two-sided tests for statistical significance. RESULTS: The number of pancreatic ducts (interlobular, intralobular, and centro-acinar-cancer-prone regions in certain rodent models and in humans) and acini per mouse in the Western-style diet group was similar to that in the control diet group during the entire feeding period (P = .76, .32, .93, and .42, respectively). Statistically significant higher BrdU-labeling indices of the ductal interlobular and intralobular epithelial cells were seen in mice fed the Western-style diet than in mice fed the control diet during the entire observation period (P = .014 and .016, respectively). There was no statistically significant difference (P = .098) between both diet groups in the BrdU-labeling indices of the centroacinar epithelial cells. CONCLUSIONS: A Western-style diet induced pancreatic epithelial cell hyperproliferation in mice, further suggesting that increased fat content and decreased calcium and vitamin D contribute to the development of pancreatic neoplasms.     

Helicobacter pylori gastric infections in children

OBJECTIVES: Numerous reports have established the association of Helicobacter pylori and recurrent abdominal pain in children. We investigated the clinical, bacteriological and therapeutic features of our patients seen over a 1 year period. METHODS: We investigated 121 children during 1992 in Hospital Saint Vincent-de-Paul, Paris. At endoscopy, biopsies were taken and sent for histology and bacteriology and urease testing. A decision regarding treatment by amoxicillin and metronidazol was made after positive results of bacteriology and/or histology. RESULTS: Heliobacter pylori was found in 47 antral biopsies after pathology examination with Giemsa staining alone 16 times, bacterial culture 9 times and both methods 22 times. Abdominal pain was the prominent symptom, occurring in 35.5% of Helicobacter pylori+patients. In 25 of the positive negative patients, a nodular gastritis was observed (53.1%) and in 27.6% of them a weight loss or a delay in weight gain. Few patients became after combined treatment with amoxicillin and metronidazol whereas eradication rates after triple therapy with amoxicillin-metronidazol and H2 antagonist or proton pump blocker were higher. CONCLUSION: Helicobacter pylori related gastritis is a common cause of abdominal complaints in children. The most common symptom is recurrent abdominal pain. Antral nodularity is a peculiar endoscopic finding in children. Two-drug therapy associating amoxicillin-metronidazol is often ineffective to eradicate the bacteria whereas eradication rates after triple therapy amoxicillin-metronidazol and H2 antagonist or proton pump blocker are higher.     

Two mechanisms for the recapture of extracellular GM2 activator protein: evidence for a major secretory form of the protein

The GM2 activator protein is a small monomeric protein containing a single site for Asn-linked glycosylation. Its only proven in vivo function is to act as a substrate specific cofactor for the hydrolysis of GM2 ganglioside by lysosomal beta-hexosaminidase A. However, we and others have shown it can act as a general glycolipid transporter at neutral pH in vitro. Any other possible in vivo functions would require that some of the newly synthesized activator molecules not be targeted to the lysosome. The lysosomal targeting mechanism for the activator has not been conclusively identified. While earlier reports suggested that it is likely through the mannose-6-phosphate receptor, another more recent report demonstrated that deficient human cells could recapture nonglycosylated, bacterially produced activator, suggesting its use of an alternate targeting pathway. Here, we demonstrate that the mannose-6-phosphate pathway is likely the major intracellular, biosynthetic route to the lysosome, as well as a high affinity recapture pathway for the endocytosis of activator protein from extracellular fluids. Additionally, we show that there exists a second lower affinity recapture pathway that requires its native protein structure, is carbohydrate independent, and likely does not involve its ability to bind glycosphingolipids in the plasma membrane. Finally, we document that the pool of newly synthesized precursor activator protein contains a majority of molecules with a complex-type oligosaccharide, which cannot contain a functional mannose-6-phosphate targeting signal. These molecules makeup the secreted forms of the protein in normal human fibroblasts.     

Going under to stay on top, revisited: Results of a colloquium on underground space utilization

This report summarizes the results of a three-day colloquium, held in Minnesota in July 1995, to address issues related to underground space utilization. The colloquium was convened by the Underground Space Center, with major support from the National Science Foundation, Directorate for Engineering, and the Federal Highway Administration.     

The complex backpropagation algorithm

The backpropagation (BP) algorithm that provides a popular method for the design of a multilayer neural network to include complex coefficients and complex signals so that it can be applied to general radar signal processing and communications problems. It is shown that the network can classify complex signals. The generalization of the BP to deal with complex signals should make it possible to expand the line of applications of this powerful nonlinear signal processing algorithm