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At least 649 records · Page 36Linked to original sources
PubMed1997

[Metamorphopsia and transient increase in the cerebral blood flow of the left occipital pole on 123I-IMP SPECT: a case report].

A 55-year-old right-handed man suddenly developed unformed visual hallucination of rainbow-colored balls coming out from the lower quadrant of the right visual field. Visual field examination revealed a right lower quadrant homonymous hemianopia. Metamorphopsia of the hand or face appeared 6 days later when he looked at his hands or at the face in the mirror, and persisted for about 10 minutes. 123I-IMP SPECT demonstrated a marked increase in CBF of the left occipital pole while the patient realized the visual symptoms, and a marked decrease in CBF after the symptoms disappeared. T1 and T2-weighted MRIs of the brain were unremarkable, but the Gd-DTPA-enhanced T1-weighted MRI showed high signal in the subcortical white matter of the left occipital pole. The metamorphopsia was induced probably by the activation of the left occipital lesion by the epileptogenic mechanism although the nature of the lesion remained unclarified.

Amphetamines↗
PubMed1998

Giant depolarizing potentials: the septal pole of the hippocampus paces the activity of the developing intact septohippocampal complex in vitro.

In neonatal hippocampal slices, recurrent spontaneous giant depolarizing potentials (GDPs) provide neuronal synchronized firing and Ca2+ oscillations. To investigate the possible role of GDPs in the synchronization of neuronal activity in intact neonatal limbic structures, we used multiple simultaneous electrophysiological recordings in the recently described preparation of intact neonatal septohippocampal complex in vitro. Combined whole-cell (in single or pairs of cells) and extracellular field recordings (one to five simultaneous recording sites) from the CA3 hippocampal region and various parts of the septum indicated that spontaneous GDPs, which can be initiated anywhere along the longitudinal hippocampal axis, are most often initiated in the septal poles of hippocampus and propagate to medial septum and temporal poles of both hippocampi simultaneously. GDPs were abolished in the medial septum but not in the hippocampus after surgical separation of both structures, suggesting hippocampal origin of GDPs. The preferential septotemporal orientation of GDP propagation observed in the intact hippocampus was associated with a corresponding gradient of GDP frequency in isolated portions of hippocampus. Accordingly, most GDPs propagated in the septotemporal direction in both septal and temporal hippocampal isolated halves, and whereas GDP frequency remained similar in the septal part of hippocampus after its surgical isolation, it progressively decreased in more temporally isolated portions of the hippocampus. Because GDPs provide most of the synaptic drive of neonatal neurons, they may modulate the development of neuronal connections in the immature limbic system.

Animals↗
PubMed1976

[Contribution toward determining the inner equilibrium of the spinal column (pivotal point as temporary pole) (author's transl)].

The estimation of the centre of rotation of a spine segment can be shown as a transient pole, which follows the polar curve of the movement of the upper segment of the spine, relative to the lower one. With the help of X-ray, it is possible to evaluate two separate positions of the pole, from the normal position to the medium flexion and from the medium to the extreme flexion of the lumbal segment. Based on these expected values, as well as their intervals, pathological cases can be recognized, which is also shown in an example.

Biomechanical Phenomena↗
PubMedDate not supplied

[Behavioral reactions in simians after ablation of the pole of the frontal cortex].

In 4 baboons and 3 macaques ablation of the frontal pole (area 10) as compared to other areas of the frontal cortex did not impair previously elaborated instrumental reflexes of different complexity and did not interfere with the elaboration of new ones. An increase in stability, speed, accuracy and intensity of conditioned reflexes was noted. The ablation did not result in motor or vegetative disturbances. In the general behaviour inhibitory elements disappeared along with an enhancement in motor goal-directed activity. It is suggested that frontal poles do not participate in closing-function but control conditioned reflexes and complex behaviour by means of inhibitory influences.

Animals↗
PubMed1981

Angioarchitecture of the ciliary artery circulation of the posterior pole.

Morphologic findings on scanning electron microscopy of vascular cast of the posterior pole in primates are presented. The prelaminar region of the optic disc received the majority of its blood supply from the short posterior ciliary arteries, mainly from direct branches arising from peripapillary arterioles surrounding the optic nerve but also from indirect branches from the peripapillary choroid. The capillaries from this prelaminar region drained directly into the central retinal vein. The peripapillary choriocapillaris was a single layer of anastomosing capillaries supplied by precapillary choroidal arterioles. The peripapillary choriocapillaris was not seen to contribute to the vascular supply of the optic disc. Our results are in general agreement with those of previous scanning electron microscopy studies of the vascular supply of the distal part of the optic nerve.

Animals↗
PubMed1996

Corticotropin-releasing factor-containing axon terminals synapse onto catecholamine dendrites and may presynaptically modulate other afferents in the rostral pole of the nucleus locus coeruleus in the rat brain.

Physiological and immunohistochemical studies have suggested that corticotropin-releasing factor (CRF), the hypophysiotropic peptide that initiates endocrine responses to stress, may serve as a neurotransmitter to activate noradrenergic neurons in the nucleus locus coeruleus (LC). We combined immunoperoxidase labeling for CRF and immunogold-silver localization of the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) in single sections through the rat LC to determine potential substrates for interactions between these two transmitters. Light microscopic analysis indicated that CRF processes are dense and highly varicose in the rostral LC region in the vicinity of noradrenergic dendrites. Electron microscopy of this rostral region revealed that immunoperoxidase labeling for CRF was mainly restricted to axons and axon terminals and was rarely seen in somata or dendrites. Axon terminals containing CRF immunoreactivity varied in size, content of synaptic vesicles, and formation of synaptic specializations. The postsynaptic targets of the CRF-labeled axon terminals consisted of both TH-labeled dendrites and dendrites lacking detectable TH-immunoreactivity. Of 113 CRF-immunoreactive axon terminals, approximately 70% were in direct contact with TH-labeled and unlabeled dendrites. Of the CRF-labeled axon terminals forming synapses with TH-labeled and unlabeled dendrites, they were either of the asymmetric (excitatory type; 19%) or symmetric (inhibitory type; 11%) variety or did not form identifiable contacts in the plane of section analyzed. Unlabeled axon terminals and glial processes were also commonly located adjacent to the plasma membranes of CRF-labeled axon terminals. These results provide the first direct ultrastructural evidence that axon terminals containing CRF-immunoreactivity 1) directly contact catecholamine-containing dendrites within the rostral pole of the LC, 2) may presynaptically modulate other afferents, and 3) are often enveloped by astrocytic processes.

Animals↗
PubMed1998

Adaptive pole placement control algorithm for DO-control in beta-lactamase production.

The dissolved oxygen (DO) is an important variable in aerobic fermentations and affects the cell growth and product formation. Dissolved oxygen control is difficult in batch fermentations because of the time-varying conditions, time delays, and the probe dynamics. Modeling of the various patterns of biological activity in fermentations and their impact on the DO process dynamics is essential to both achieve a satisfactory control and to track the aforementioned patterns. An adaptive pole placement algorithm with time-delay compensation was used for controlling the DO, coupled with system identification using recursively estimated autoregressive models with exogeneous inputs (ARX). The flow rate of O2 in a constant flow rate gas inlet mixture is used as the manipulated variable. Supervision and coordination techniques are applied to improve the control performance. The control performance is affected by the accuracy of the model prediction and the selected time delay. The effect of DO level on the productivity of beta-lactamase using Bacillus subtilis under oxygen-limited conditions is investigated. Beta-lactamase stability is improved under prolonged growth conditions with low DO levels.

Aerobiosis↗
PubMed1982

Scanning electron microscopy studies of the vascular pole of the rat glomerulus.

The vascular poles of 30 renal corpuscles were studied in critical-point dried renal cortex of the Munich-Wistar rat by scanning electron microscope (SEM). In 28 cases one afferent and one efferent arteriole were observed; one was done in the Sprague-Dawley rat, where 34 renal corpuscles were examined. One afferent and a single efferent arteriole were found in 32 cases; in one case only one afferent and two efferent arterioles were observed. In another case it was questioned whether a single or a double efferent arteriole is present. In addition, the specimens allowed an evaluation of the area where the extraglomerular mesangium passes into the mesangial cells of the glomerular tuft. This area was found to be rather small to represent a "punctum fixum" for a contraction of the entire mesangium.

Animals↗
PubMed1992

Molecular movements in oocyte patterning and pole cell differentiation.

Central to the differentiation and patterning of the Drosophila oocyte is the asymmetric intracellular localization of numerous mRNA and protein molecules involved in developmental signalling. Recent advances have identified some of the molecules mediating oocyte differentiation, specification of the anterior pole of the embryo, and determination of the embryonic germ line. This work is considered in the context of the classical model of the germ plasm as a cytoplasmic determinant for germ cell formation.

Animals↗
PubMed2001

Centrosome and spindle pole microtubules are main targets of a fluorescent taxoid inducing cell death.

Microtubules offer a very large local concentration of binding sites for cytotoxic taxoids or for hypothetical endogenous regulators. Several compounds from diverse sources stabilize microtubules and arrest cell division similarly to the antitumour drug Taxol. We have investigated the subcellular location of the Taxol binding sites, employing a fluorescent taxoid (FLUTAX) that reversibly interacts with the Taxol binding sites of microtubules and induces cellular effects similar to Taxol. The specific binding of FLUTAX to a fraction of the available cellular binding sites effectively inhibits division of cultured human tumour cells at G(2)/M, and triggers apoptotic death. The loci of reversible binding, directly imaged in intact U937 cells treated with cytotoxic doses of fluorescent taxoid are the centrosomes, with a few associated microtubules in interphase cells, and the spindle pole microtubules in mitotic cells, instead of uniformly labelling the microtubule cytoskeleton. Cytoskeletal lesions induced and visualized with FLUTAX consist of microtubule bundles and abnormal mitoses, including monopolar spindles and highly fluorescent multipolar spindles. The multiple asters and monopolar spindles mark arrested U937 leukaemia and OVCAR-3 ovarian carcinoma cells on their path to apoptosis (as well as K562, HeLa, and MCF-7 cells). Depending on the FLUTAX treatment, OVCAR-3 cells died from abnormal mitosis or from a subsequent interphase with double chromatin content and lobulated nuclei (micronuclei), indicating impairment of centrosome separation. Fragmented centrosomes could be observed in FLUTAX-treated non-transformed 3T3.A31 cells, which developed micronuclei but were resistant to apoptosis. These results strongly suggest that centrosomal impairment by taxoid binding during interphase, in addition to the suppression of the kinetochore microtubule dynamics in the mitotic spindle, is a primary cause of cell cycle de-regulation and cell death.

Binding Sites↗
PubMed1988

Cell-cycle modulation of MPM-2-specific spindle pole body phosphorylation in Aspergillus nidulans.

MPM-2 is a monoclonal antibody that interacts with mitosis-specific phosphorylated proteins in many different organisms. Immunocytochemistry of tissue culture cells has shown that MPM-2 stains centrosomes, chromosomes, kinetochores, and spindles. In this paper, we demonstrate that MPM-2 staining colocalizes with the spindle pole body (SPB) of Aspergillus nidulans and that SPB staining varies during the mitotic cycle. In an unsynchronized population, about one-fourth to one-third of the cells stain with MPM-2 at the spindle plaques or SPBs. Nuclei in mitosis have two SPBs localized at the ends of the spindle, both of which stain with MPM-2. To determine when MPM-2 staining appears, we have examined the effects of temperature-sensitive cell-cycle mutations that block nuclear division in S or G2. Only a very small fraction of cells blocked in S-phase stain with MPM-2. In contrast, a large fraction of cells blocked in G2 stain brightly at the SPB. These data suggest that MPM-2 reactivity of SPBs appears in G2. Moreover, the fact that cells blocked in G2 showed MPM-2 staining but no spindles suggests that reactivity of SPBs occurs prior to mitosis but is not sufficient to trigger spindle formation. When G2-blocked cells were downshifted to permissive temperature, they generated a mitotic spindle with an SPB at each end. Both SPBs stained with MPM-2 in all of the mitotic cells.

Antibodies, Monoclonal↗
PubMed1985

Cortical and subcortical afferent connections of the primate's temporal pole: a study of rhesus monkeys, squirrel monkeys, and marmosets.

The afferent connections of the primate's temporopolar cortex were investigated with the retrograde horseradish peroxidase technique. Old World and New World monkeys received small unilateral injections of horseradish peroxidase. These labeled cells in a number of cortical, thalamic, and brainstem regions and in a few further telencephalic and diencephalic regions. Cortically, the neighboring areas of the inferior and superior temporal gyrus and the insula contained a considerable number of labeled cells. Furthermore, a substantial projection arose from the orbitofrontal and the frontopolar cortex. The cingulate gyrus contained only very few labeled cells. Interhemispherically, corticocortical connections arose mainly from temporal lobe areas. Labeled cells were seen in various regions of the basal forebrain and cells labeled only faintly in the lateral and basal accessory nuclei of the amygdala. The claustrum contained labeled neurons only in one rhesus monkey. On the diencephalic level, the caudal medial portion of the medial pulvinar was the principal thalamic source of afferents to the temporopolar cortex. Furthermore, labeled cells were found in the neighboring, caudal part of the mediodorsal nucleus, within and along the nucleus limitans, in the medial geniculate nucleus, and in several nuclei of the nonspecific system. The fields of Forel, the zona incerta, and lateral and dorsomedial hypothalamic areas contained a few labeled cells. Within the brainstem of the rhesus monkeys those regions projecting diffusely to the cortex contained a few labeled neurons. Furthermore, these brains had some labeled cells in the regions of the nuclei medialis annuli aqueductus, tractus mesencephalicus nervi trigemini, and trochlearis. Although among the three species differences in the cortical and thalamic projection patterns were observed, the regions projecting most densely to the temporal pole were similar in principle. This statement holds in particular for cortical and thalamic sites. However, the greatest number of labeled cells was found in the rhesus monkey, a fact that cannot be attributed solely to the size of the horseradish peroxidase injections and the size of the brain, but that appears rather to represent a true species difference. From our results we conclude that the temporopolar cortex constitutes a cortical area necessary for effective affectional-sensory integration.

Afferent Pathways↗
PubMed1994

Interaction with calmodulin is required for the function of Spc110p, an essential component of the yeast spindle pole body.

NUF1/SPC110, encoding a nuclear filament-related protein which is a component of the yeast spindle pole body (SPB), has been identified in a screen designed to isolate genes encoding targets of yeast calmodulin. Spc110p interacts with calmodulin by two different criteria and the calmodulin interacting region has been localized within the C-terminus of the protein. Point mutations between residues 898 and 917 further define the calmodulin binding site within this region. Mutations in this domain which abolish calmodulin binding in vitro prevent Spc110p function in vivo, demonstrating that calmodulin binding by Spc110p has important functional consequences. In keeping with a role for calmodulin in Spc110p function, we show that calmodulin localizes to the yeast SPB when cells are prepared under appropriate conditions. Non-functional mutant Spc110 proteins which cannot bind calmodulin are present at lowered steady-state levels in the cell; when their level is increased by elevated gene dosage, partial recovery of Spc110p function is seen. Overexpression of calmodulin suppresses the defect(s) associated with the mutant Spc110 proteins, supporting the notion that Spc110p stability is a consequence of its ability to bind calmodulin and pointing to a direct role for calmodulin in Spc110p function.

Alleles↗
PubMed1995

Yeast spindle pole body duplication gene MPS1 encodes an essential dual specificity protein kinase.

The MPS1 gene has been previously identified by a mutant allele that shows defects in spindle pole body (SPB) duplication and cell cycle control. The SPB is the centrosome-equivalent organelle in the yeast Saccharomyces cerevisiae, and it nucleates all the microtubules in the cell. We report the isolation of the MPS1 gene, which encodes an essential protein kinase homolog. The MPS1 open reading frame has been fused to those that encode the LexA protein or the GST protein and both of these constructs function in yeast. The fusion proteins have been affinity-purified from yeast extracts and the GST chimeric protein has been found to be a phosphoprotein. Both proteins have been used to demonstrate intrinsic in vitro protein kinase activity of Mps1p against exogenous substrates and itself (autophosphorylation). A mutation predicted to abolish kinase function not only eliminates in vitro protein kinase activity, but also behaves like a null mutation in vivo, suggesting that kinase activity contributes to the essential function of the protein. Phosphoamino acid analysis of substrates phosphorylated by Mps1p indicates that this kinase can phosphorylate serine, threonine and tyrosine residues, identifying Mps1p as a dual specificity protein kinase.

Amino Acid Sequence↗
PubMed1976

Anterior position of the lower pole of the right kidney: potential confusion with right upper quadrant mass.

A group of patients with anterior position of the lower pole of the right kidney were examined with ultrasound to evaluate a palpable right upper quadrant mass. After it was determined, with the use of ultrasound, that the palpable mass represented the kidney, no further evaluations were necessary. This appearance is seen fairly often in normal individuals and should be considered a normal variant. The possible anatomic explanation for this appearance is discussed.

Abdominal Neoplasms↗
PubMed1983

Serial section reconstruction of the neural poles of hair cells in the human organ of Corti. I. Inner hair cells.

Study of the anatomy of the cochlea, and in particular the morphology of synaptic relationships between hair cells and cochlear neurons, is essential for elucidation of the mechanisms of transduction of mechanical acoustic signals into electrical neural events. Because considerable gaps remain in our understanding of the microscopic anatomy of these synapses, particularly in the human, a reconstruction of neural pole of inner hair cells of the human organ of Corti was performed. The data are based on 526 serial sections from the basal turn (10 mm region) and 356 serial sections from the middle turn (26 mm region). This provided complete data on 3 and partial data on 5 inner hair cells. Afferent terminals on inner hair cells were variable in size, ranging 1 to 20 micrometers in diameter. Branching of large fibers to produce multiple terminals innervating from 1 to 3 inner hair cells was common. Each inner hair cell received approximately 6 to 8 different nerve terminals. In addition, each terminal possessed a variable number of synaptic contacts. Junctional membrane specialization consisted of synapses, desmosomes, coated vesicles and arrays of microtubules and membrane cisternae. Specialization at synapses consisted of asymmetrical membrane thickening. At inner hair cells the postsynaptic membrane was thicker than the presynaptic membrane. Eighty-three percent of synapses had presynaptic bodies. Vesiculated efferent terminals synapsed on afferent fibers at the base of inner hair cells, but never directly on the inner hair cell. These anatomical data demonstrate distinct differences between the human and animal inner ear, which are important in the interpretation of neurophysiological data in animals and the formulation of hypotheses that involve assumptions crossing species.

Desmosomes↗
PubMed1994

Structural modification of spindle pole bodies during meiosis II is essential for the normal formation of ascospores in Schizosaccharomyces pombe: ultrastructural analysis of spo mutants.

In order to characterize the morphological steps defined by sporulation (spo) genes during the formation of ascospores in the fission yeast Schizosaccharomyces pombe, we performed an electron microscopic study of the ultrastructure of the spindle pole body (SPB) and of the development of the forespore membrane during the second meiotic division (meiosis II) in sporulation-deficient (spo) mutants (spo4, spo5, spo14 and spo18). No difference was found in terms of the function and the structure of the SPB during the first meiotic division (meiosis I) between the four mutants and wild-type cells. However, during meiosis II, the spo4 and spo18 mutants underwent nuclear division but in neither case were the SPBs modified nor were forespore membranes formed. The SPBs of the spo18 mutant diminished in size after meiosis II and eventually disappeared after 18 h in sporulation medium. By contrast, the SPBs of the spo4 mutant remained unchanged even after an 18-h incubation. The outer plaques of SPBs of spo5 and spo14 mutants were sufficiently modified to allow them to initiate development of the forespore membrane, but the membrane had an abnormally expanded lumen and did not enclose the nuclei during meiosis II. The spo5 mutant produced anucleate spore-like bodies while the spo14 mutant formed unorganized structures with irregular peripheries which, presumably, contained spore-wall precursors, instead of anucleate spore-like bodies. We conclude that the modification of the SPB is essential for the formation of ascospores and at least two genes (spo5 and spo14) participate in the development of the forespore membrane. The defective phenotypes define discrete steps in the development of ascospores, which proceeds via steps defined by the mutant spo4, spo18, spo14 and spo5 genes respectively. Our observations provide further substantial evidence that the SPB plays a pivotal role in the normal development of ascospores in yeasts.

Meiosis↗
PubMed2002

Molecular and structural characterization of the spindle pole bodies in the fission yeast Schizosaccharomyces japonicus var japonicus.

The structure and localization of the microtubule organization centres (MTOCs) of the fission yeast Schizosaccharomyces japonicus var. japonicus were examined by fluorescence microscopy and electron microscopy. Spindle pole bodies (SPBs), which are the fungal equivalent of centrosomes, of Sz. japonicus were visualized by immunofluorescent staining using a monoclonal anti-gamma-tubulin antibody. The behaviour of the SPBs during the cell cycle mostly coincided with previous reports on the most widely used fission yeast Schizosaccharomyces pombe. We cloned the gamma-tubulin gene from Sz. japonicus by PCR using redundant sets of primers corresponding to conserved regions of known gamma-tubulins. The predicted amino acid sequence of Sz. japonicus gamma-tubulin was most similar to the Sz. pombe gamma-tubulin. Under the electron microscope, the SPBs of Sz. japonicus were detected as electron-dense multilayered structures located just outside the nuclear envelope. The SPBs of Sz. japonicus were composed of three electron-dense layers and were surrounded by fuzzy material. Each layer showed structural changes according to the progression of the cell cycle. In mitotic cells, the SPBs were located on the fenestrae of the nuclear envelopes through which the mitotic spindle microtubules ran into the nucleoplasm. Our results show that Sz. japonicus is a very potent and attractive organism for the investigation of the microtubule nucleation system and morphogenesis in yeasts. The Accession No. for the nucleotide sequence of the Sz. japonicus gtb1(+) gene is AF159163.

Amino Acid Sequence↗