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The primate temporal pole: its putative role in object recognition and memory.

In this article, we consider both the ventral temporopolar cortex and the perirhinal cortex (areas 35 and 36) as the anterior ventromedial temporal (aVMT) cortex, and discuss its role based on recent data in monkeys and human subjects. In monkeys, the aVMT cortex receives its primary input from area TE, and only minor input from other cortical areas. Laminar patterns of connections suggest that the aVMT cortex is a hierarchically higher-order area than area TE. Lesions of this cortex produce deficits in the learning and performance of visual memory tasks. Neurons in the aVMT cortex respond selectively to complex stimuli and changes in activity related to visual memory tasks. In humans, damage of this cortex induces deficits in the recognition of familiar objects and faces. The aVMT cortex is activated during recognition of familiar faces. In addition, the aVMT cortex is one of the most vulnerable areas in Alzheimer's disease. All these data indicate that the aVMT cortex is a higher-order visual cortical area that is related to object recognition and memory. The anterior area TE has been implicated in both functions. We propose here that these areas and the anterior entorhinal cortex are designated as the temporal pole, a brain region which is specialized for both object recognition and memory.

Animals↗

Characterization of actin microfilaments at the apical pole of thyroid cells.

In thyroid cells (rat or hog), actin has been detected by immunofluorescence with an antiactin antibody and, in electron microscopy by decoration "in situ" with heavy meromyosin. The antibody as the heavy meromyosin method have shown that actin microfilaments are especially localized at the apical pole of the cells, in a region where thin filaments are usually observed by conventional methods of electron microscopy. These microfilaments are attached to the apical membrane at the ends of the microvilli and form dense bundles at their cores. They are polarized towards the interior of the cell. Decorated filaments are also organized in a clear network, parallel to the apical membrane; they are associated with microvillar bundles, but also with small apical vesicles and lateral membranes, in tight or gap junctions.

Actins↗

Monoclonal antibody production against a subcellular fraction of vegetal pole cytoplasm containing the germ plasm of Xenopus 2-cell eggs.

In attempts to understand the molecular nature of substances localized in the germ plasm (GP), monoclonal antibodies against a subcellular fraction of vegetal pole cytoplasm containing the GP of Xenopus 2-cell eggs were produced. The monoclonal antibody produced by the hybridoma cell line (designated as no 48) reacted specifically with the GP of embryos at the cleavage stages. Beyond the gastrula stage, the antibody reacted with not only the GP of germ line cells but also the cytoplasm of somatic cells. By immunoblotting analysis with two-dimensional (2-D) gel the antibody was shown to react with two protein spots of approx. 40 kDa, with a pI of 6.0-6.5.

Animals↗

Centrin, centrosomes, and mitotic spindle poles.

Centrin is a ubiquitous protein component of centrosomes and mitotic spindle poles. cDNA clones encoding centrin have been identified from vertebrate sources, and their sequences demonstrate that centrin is a highly conserved member of the EF-hand superfamily of calcium-binding proteins. Analysis of yeast and Chlamydomonas centrin mutants and experimental studies suggest that centrin has an essential role in the duplication of the centrosomes during the cell cycle, and in microtubule severing.

Amino Acid Sequence↗

Neonatal lesions of the ventral hippocampal formation alter GABA-A receptor subunit mRNA expression in adult rat frontal pole.

BACKGROUND: Gamma-aminobutyric acid (GABA)-ergic function is altered in schizophrenia. Of particular interest is the altered central nervous system expression of GABA-A receptor subunits, as changes in subunit expression account for recognized differences in mammalian brain function making them inviting targets for novel psychotropic agents. Excitotoxic neonatal lesions of the ventral hippocampal formation (NVHL) in rats reproduce numerous aspects of schizophrenia, including decreased mRNA expression of the GABA synthesizing enzyme glutamic acid decarboxylase-67, though their impact on subunit expression is unknown. METHODS: We utilized quantitative reverse transcription polymerase chain reaction to investigate mRNA expression of the alpha1, alpha5, and gamma2s GABA-A receptor subunits in the frontal pole of water-deprived adult NVHL and SHAM-lesioned animals. RESULTS: Messenger RNA expression for all three GABA-A subunits (alpha1-NVHL: 18.5 +/- 1.6 pg/mug total pooled RNA, SHAM: 11.3 +/- .4; alpha5-NVHL: 5.1 +/- .6; SHAM: 3.5 +/- .7; and gamma2s-NVHL: 10.8 +/- 1.7; SHAM: 7.2 +/- 1.5) was higher in NVHL, though only levels of alpha1 differed significantly after correction for multiple comparisons. Levels of a control mRNA, neuronal specific enolase, were similar in the two groups. CONCLUSIONS: These data indicate that NVHL reproduce changes in cortical GABA-A receptor subunit expression seen in schizophrenia, suggesting this animal model may facilitate efforts to clarify the physiologic significance of altered GABA function and to develop novel targets for therapeutic interventions.

Animals↗

Regulation of ADMP and BMP2/4/7 at opposite embryonic poles generates a self-regulating morphogenetic field.

Embryos have the ability to self-regulate and regenerate normal structures after being sectioned in half. How is such a morphogenetic field established? We discovered that quadruple knockdown of ADMP and BMP2/4/7 in Xenopus embryos eliminates self-regulation, causing ubiquitous neural induction throughout the ectoderm. ADMP transcription in the Spemann organizer is activated at low BMP levels. When ventral BMP2/4/7 signals are depleted, Admp expression increases, allowing for self-regulation. ADMP has BMP-like activity and signals via the ALK-2 receptor. It is unable to signal dorsally because of inhibition by Chordin. The ventral BMP antagonists Sizzled and Bambi further refine the pattern. By transplanting dorsal or ventral wild-type grafts into ADMP/BMP2/4/7-depleted hosts, we demonstrate that both poles serve as signaling centers that can induce histotypic differentiation over considerable distances. We conclude that dorsal and ventral BMP signals and their extracellular antagonists expressed under opposing transcriptional regulation provide a molecular mechanism for embryonic self-regulation.

Animals↗

Cdc28/Cdk1 regulates spindle pole body duplication through phosphorylation of Spc42 and Mps1.

Duplication of the Saccharomyces cerevisiae spindle pole body (SPB) once per cell cycle is essential for bipolar spindle formation and accurate chromosome segregation during mitosis. We have investigated the role that the major yeast cyclin-dependent kinase Cdc28/Cdk1 plays in assembly of a core SPB component, Spc42, to better understand how SPB duplication is coordinated with cell cycle progression. Cdc28 is required for SPB duplication and Spc42 assembly, and we found that Cdc28 directly phosphorylates Spc42 to promote its assembly into the SPB. The Mps1 kinase, previously shown to regulate Spc42 phosphorylation and assembly, is also a Cdc28 substrate, and Cdc28 phosphorylation of Mps1 is needed to maintain wild-type levels of Mps1 in cells. Analysis of nonphosphorylatable mutants in SPC42 and MPS1 indicates that direct Spc42 phosphorylation and indirect regulation of Spc42 through Mps1 are two overlapping pathways by which Cdc28 regulates Spc42 assembly and SPB duplication during the cell cycle.

Alleles↗

The fission yeast homolog of the human transcription factor EAP30 blocks meiotic spindle pole body amplification.

Centrosome aberrations caused by misregulated centrosome maturation result in defective spindle and genomic instability. Here we report that the fission yeast homolog of the human transcription factor EAP30, Dot2, negatively regulates meiotic spindle pole body (SPB, the yeast equivalent of centrosome) maturation. dot2 mutants show excess electron-dense material accumulating near SPBs, which we refer to as aberrant microtubule organization centers (AMtOCs). These AMtOCs assemble multipolar spindles, leading to chromosome missegregation. SPB aberrations were associated with elevated levels of Pcp1, the fission yeast ortholog of pericentrin/kentrin, and reducing pcp1(+) expression significantly suppressed AMtOCs in dot2-439 cells. Our findings, therefore, uncover meiosis-specific regulation of SPB maturation and provide evidence that a member of the conserved EAP30 family is required for maintenance of genome stability through regulation of SPB maturation. EAP30 is part of a transcription factor complex associated with acute myeloid leukemia, so these results may have relevance to human cancer.

Amino Acid Sequence↗

Development of an instrumented pole test for use as a gait laboratory quality check.

Gait analysis is becoming an increasingly common procedure in the diagnosis of movement disorders. Core equipment includes 3D tracking cameras and force platforms. Important clinical decisions are made with the assistance of gait data, therefore it is essential to have confidence in its quality. Calibration has a major role to play here and this paper describes the development of a daily spot check pole test for use in a gait laboratory. The work develops previous such tests, by the addition of a force transducer, removing the need to assume an idealised force system and allowing amplifier gain ranges to be checked. Repeatability results are presented, along with the response to 14 simulated error modes. The test provides useful data on system performance and is able to identify and diagnose failures. Failure thresholds can be tightened as accuracy improves, particularly in the area of centre of pressure measurement. Spot checks, such as this, along with full calibration tests, will become essential as new standards are introduced into clinical practice.

Biomechanical Phenomena↗

Arthroscopic techniques for wrist arthritis (radial styloidectomy and proximal pole hamate excisions).

Over the last 2 decades, arthroscopy has assumed a greater role in the treatment of disorders of the wrist. The arthroscopic treatment of radioscaphoid arthritis and ulnar hamate impaction provides the benefits of being minimally invasive, with less morbidity, earlier motion, less recovery time, early return to work, and greater patient acceptance. Both procedures are performed easily using standard arthroscopic techniques without any significant learning curve.Long-term studies need to be performed to determine the exact clinical sequelae of excision of the proximal pole of the hamate, specifically on the biomechanics of the triquetrohamate articulation.

Arthritis↗

The basket plate in the osteosynthesis of comminuted fractures of distal pole of the patella.

The purpose of this study was to evaluate the basket plate in the treatment of comminuted fractures of the distal pole of the patella (patellar apex fracture). The basket plate was designed by Smiljanić Branimir M.D., Clinical Professor of Surgery, at the Department of Surgery, The University Hospital Sestre milosrdnice, Zagreb, Croatia. In the period from 1988 to 2003, more than 100 patients with comminuted patellar apex fractures had been treated with basket plate osteosynthesis in the Department of Surgery. Only 51 patients were subsequently available for knee examination. For evaluation of the knee, we used a modified Cincinnati knee rating system, using a manual dynamometer in the evaluation of the knee extension. The results were excellent in 30 patients, good in 16 and satisfactory in 5 patients; no poor results were observed. The stability of the osteosynthesis by basket plate allows osseous consolidation if the fracture and permits loading the leg with full body weight early in the postoperative period.

Adult↗

Post-LASIK myopic shift after a trek in the North Pole.

Bilateral laser in situ keratomileusis was performed in a 37-year-old male ethnic Chinese adventurer. Eight weeks postoperatively, the patient made an unassisted trek to the geographic North Pole. After 2 weeks in this environment, a myopic shift of more than -1.50 diopters occurred in both eyes. The myopic shift resolved over 2 months when the patient returned to a tropical climate. Using Orbscan corneal topography, we propose that the myopic shift was attributed to biomechanical changes in the cornea induced by corneal dehydration in the Arctic environment.

Adult↗

Anthropogenic iodine-129 in seawater along a transect from the Norwegian coastal current to the North Pole.

Variation in the concentrations of iodine-129 (129I, T1/2=15.7 Myr), a low-level radioactive component of nuclear fuel waste, is documented in surface waters and depth profiles collected during 2001 along a transect from the Norwegian Coastal Current to the North Pole. The surface waters near the Norwegian coast are found to have 20 times higher 129I concentration than the surface waters of the Arctic Ocean. The depth profiles of 129I taken in the Arctic Ocean reveal a sharp decline in the concentration to a depth of about 300-500 m followed by a weaker gradient extending down to the bottom. A twofold increase in the 129I concentration is observed in the upper 1000 m since 1996. Based on known estimates of marine transient time from the release sources (the nuclear reprocessing facilities at La Hague, France, and Sellafield, UK), a doubling in the 129I inventory of the top 1000 m of the Arctic Ocean is expected to occur between the years 2001 and 2006. As 129I of polar mixed layer and Atlantic layer of the Arctic Ocean is ventilated by the East Greenland Current into the Nordic Seas and North Atlantic Ocean, further dispersal and increase of the isotope concentration in these regions will be encountered in the near future.

Arctic Regions↗

Subtle cortical thinning in the temporal pole in middle-aged APOE-ε4 and PICALM (rs3851179) AA/AG carriers without dementia.

The symptoms of Alzheimer's disease (AD) are caused by neurodegeneration and atrophy in particular brain regions, especially in the temporal lobe. However, the influence of genetic risk on cortical thickness prior to dementia onset, remains unclear. This study aimed to explore the relationship between AD genetic risk (related to APOE and PICALM genes) and cortical thickness in selected regions of interest (ROIs) in middle-aged individuals without dementia. Sixty-nine (N = 69) participants (34 females, 35 males; age: 55.45 ± 3.19) underwent magnetic resonance imaging (MRI). They were divided into three groups based on their genetic AD risk: A+ P+ (APOE/PICALM risk variants), A+P- (APOE risk variant, PICALM neutral variants), and the N group (APOE/PICALM neutral alleles). Cortical thickness was analyzed using CAT12 software (surface-based morphometry with the Destrieux atlas) based on T1-weighted MR images in five ROIs referred to as "the cortical signature of AD" in previous studies. The A+P- group had a thinner right temporal pole cortex than non-carriers after controlling for sex, age, and Raven's Progressive Matrices scores. Although this finding did not survive FDR correction across the 10 tested regions, it is consistent with our hypotheses and prior literature. No other differences in cortical thickness were found in the analyzed regions of AD "signature". The observed effect was restricted to single-risk APOE carriers without PICALM risk alleles. Therefore, further research is needed to understand the genetic interplay between these two genes in conferring AD risk.

Humans↗

Temporal pole morphology and psychopathology in males with schizophrenia.

A dysfunction of the paralimbic system has been implicated in the pathophysiology of schizophrenia. The temporal pole (TP) is a relevant component of the paralimbic circuit. Functional and structural imaging studies have shown circumscribed abnormalities in the TP. Subjects were 30 controls and 30 schizophrenia patients. Cortical surface size and gray matter volume of the TP were accurately measured to explore the morphology of the TP cortex and the relationship of TP measures to clinical variables in patients with schizophrenia. Correlations between structural measures and clinical dimensions, duration of illness, and cumulative neuroleptic exposure were determined. Neither macroscopic abnormalities in the TP nor differences in the pattern of asymmetry were demonstrated. The TP volume was correlated negatively to the psychotic and disorganized dimension scores. No other significant correlations were found. No morphological abnormalities in the TP were found in patients with schizophrenia. Interestingly, a reduction in the TP volume, a higher-order multimodal association cortex, was associated with the severity of disorganized and psychotic symptoms.

Adult↗

Optical poling effect and optical absorption of cyan, ethylcarboxyl and tert-buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline: experiment and quantum-chemical simulations.

We present here results of experimental studies and quantum-chemical simulations of optical absorption and optical poling effects performed on a new synthesized cyan, ethylcarboxyl and tert-buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline incorporated into polymer matrix or dissolved in organic solutions. The efficiency of second-order optical susceptibility d vs photoinduced power density I(p) clearly saturates to certain magnitude d(eff) at sufficient power densities (I(p) > or = 1.3 GW cm(-2)). Comparing experimental data and results of semiempirical quantum-chemical simulations one can conclude that there exists generally a good correlation between the magnitude of saturated susceptibilities d(eff) and macroscopic hyperpolarizabilities for all compounds except the chromophore 1,3-dimethyl-6-cyano-[PQ] only. The discrepancy for this compound may reflect a specific contribution of surrounding polymer matrix. According to the quantum chemical analysis the methyl-containing cyan and ethylocarcoxyl derivatives reveal four/five strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by the phenyl group causes the substantial changes of the absorption spectra mainly in the spectral range 240-370 nm. Measured and calculated absorption spectra manifest rather good agreement mainly in the part regarding the spectral positions of the first oscillator (absorption threshold). The quantum-chemical PM3 method shows the best agreement with experiment. At the same time a considerable broadening almost of all absorption bands appears as a characteristic feature of all measured spectra. The discrepancies between the calculated and the measured spectra are attributed to electron-vibronic coupling as well as to a specific rotational dynamics of phenyl rings.

Absorption↗

Robotic-assisted laparoscopic ureteroureterostomy in an adolescent with an obstructed upper pole system and crossed renal ectopia with fusion.

Ureteropelvic junction obstruction (UPJO) in crossed renal ectopia with fusion is a rare condition. Management of UPJO occurring in ectopic kidneys generally requires open surgical reconstruction. Experience with minimally invasive techniques is minimal for repair of UPJO in ectopic kidneys. We report what we believe to be the first documented case of laparoscopic ureteroureterostomy with the da Vinci robotic system in an adolescent with an obstructed upper pole system and crossed renal ectopia with fusion.

Adolescent↗

Congenital stalked fibromatous polyp of the superior pole of the tonsil containing hairless sebaceous glands.

A polyp of the size of a small bean was discovered incidentally on the superior pole of the right tonsil of a 29-year-old man. Morphologically it bore a considerable resemblance to the immature infantile variant of the sebaceous-gland nevus, the Naevus epitheliomatosus sebaceus Wolters, but its top was mature. The polyp is viewed as a congenital dysontogenic tumor which, owing to its fibromatous basis, lack of hair, and its immature and mature sebaceous glands, may be informally classified as a "missing link" between the haired pharyngeal polyp and the pure pharyngeal fibroma.

Adult↗