Cortex Fragments Research Articles

Acute vertebral collapse: CT findings in benign and malignant nontraumatic cases.

The value of computed tomography (CT) for differentiating benign from malignant causes of nontraumatic acute vertebral collapse (AVC) (associated with pain of less than 3 months duration) was evaluated. The CT findings of 34 benign (osteoporotic) and 32 malignant (metastatic or myelomatous) nontraumatic AVCs were compared. The following CT findings were significantly more frequent in benign AVCs: cortical fractures of the vertebral body without cortical bone destruction, retropulsion of a bone fragment of the posterior cortex of the vertebral body into the spinal canal, fracture lines within the cancellous bone of the vertebral body, an intravertebral vacuum phenomenon, and a thin diffuse paraspinal soft-tissue mass (PSTM). The following CT findings were significantly more frequent in malignant AVCs: destruction of the anterolateral or posterior cortical bone of the vertebral body, destruction of the cancellous bone of the vertebral body, destruction of a vertebral pedicle, a focal PSTM, and an epidural mass. CT can help distinguish benign from malignant causes of nontraumatic AVC.

Viability of immature horse oocytes cryopreserved by vitrification

The objectives of this study were, a) to compare two different vitrification techniques, the solid surface vitrification (SSV) and direct vitrification (DV) method, b) to evaluate the effect of four cryoprotectant agents and their toxicity on the morphological appearance and ultrastructural of camel ovarian cortex, c) to examine the development of oocytes recovered from the vitrified ovarian cortex. Fragments of ovarian cortex were exposed to equilibration solution consisting of TCM- 199 with 10% fetal camel serum (FCS); 0.10 M sucrose and including one of the following cryoprotectants; 20% glycerol (GLY); 3.5 M ethylene glycol (EG); 3.5 M propanediol (PROH) or 3 M dimethylsulphoxide (DMSO). After vitrification of ovarian fragments, they were warmed and evaluated by histological and transmission electron microscope. The oocytes isolated from vitrified ovarian cortex were cultured in TCM-199 at 38.5 °C under 5% CO2 for 44 h. Maturation was indicated through cumulus expansion and calculated by oocytes reaching first telophase and second metaphase (TI + MII). The percentage of morphologically normal and viable follicles of SSV was significantly higher P < 0.05 than DV group (52.9 vs. 38.1, respectively). In conclusion, viability, histological and ultrastructural observations revealed that SSV method and ethylene glycol-based freezing solution were able to remain morphology better follicle and oocyte. Additionally, most organelles of oocytes are able to recover their normal morphology in camel ovarian cortex following cryopreservation and thawing processes, and oocytes isolated from vitrified ovarian cortex can exhibit maturation and reaches to (TI + MII).

Stimulation of weak organic acid uptake in rat renal tubules by cadmium and nystatin

The uphill uptake of a weak organic acid, fluorescein, in superficial proximal tubules of the rat kidney was stimulated by CdCl 2 (0.1 mM) or nystatin (20 μM) in the absence of metabolic substrates in the incubation medium. The stimulation could be observed during the initial period of incubation (up to 30 min) only and was prevented completely by ouabain (0.1 mM), fluoroacetate (1 mM), malonate (10 mM), α-cyano-4-hydroxycinnamate (0.1 mM), phenylpyruvate (1 mM), d-malate (2 mM) or phenazine methosulfate (20 μM). In the renal cortex fragment suspension, both Cd 2+ and nystatin increased the ouabain-sensitive, basal oxygen consumption and inhibited the rate of glucose production from pyruvate, but not from lactate. In the presence of lactate (0.5–5 mM) in the incubation medium, Cd 2+ and nystatin rather inhibited fluorescein uptake, while externally added pyruvate did not influence their stimulatory effects. Taken together, these data suggest that both activation of the tricarboxylic acid cycle and export of reducing equivalents from the mitochondria to the cytosol are necessary for the stimulatory effects of Cd 2+ and nystatin on the weak organic acid uptake to develop.

Stimulatory effect of ethanol on weak organic acid uptake in rat renal tubules

Ethanol at relatively low concentrations (10–40 mM) significantly stimulated the uphill uptake of a weak organic acid, fluorescein, in the superficial proximal tubules of rat renal cortex slices, but it did not affect the rate of glucose production from lactate or pyruvate in rat renal cortex fragment suspension. In a low Na + medium, ethanol failed to stimulate fluorescein uptake, although under the conditions employed in the present study, the baseline weak organic acid uptake was not dependent on external Na +. The stimulation of fluorescein uptake by ethanol (20 mM) was abolished by an inhibitor of alcohol dehydrogenase (EC 1.1.1.1), pyrazole (1 mM), or an inhibitor of aldehyde dehydrogenase (EC 1.2.1.3), cyanamide (0.3 mM), suggesting that oxidation of ethanol mediated its effect on the uptake. Among gluconeogenesis inhibitors tested, only d-malate (2 mM) abolished the stimulatory effect of ethanol, while the rest either did not affect (quinolinate) or even slightly augmented (α-cyano-4-hydroxycinnamate and phenylpyruvate) it. The effect of ethanol was markedly increased by an inhibitor of the tricarboxylic acid cycle, fluoroacetate. It was concluded that the stimulation by ethanol of weak organic acid uptake in rat renal tubules was mediated by the production of acetate.

Effects of inhibitors of gluconeogenesis on weak organic acid uptake in rat renal tubules

Using inhibitors of gluconeogenesis (phenylpyruvate, α-cyano-4-hydroxycinnamate, quinolinate, d-malate, aminooxyacetate), we analysed mechanisms by which the gluconeogenic substrates, lactate and pyruvate, as well as a short-chain fatty acid, acetate, stimulate the uptake of a weak organic acid, fluorescein, in the rat kidney. We have shown that these inhibitors modified both the rate of glucose production from lactate and pyruvate in the renal cortex fragment suspension and the stimulatory effects of the metabolic substrates on fluorescein uptake in superficial proximal tubules in the renal cortex slices. The peculiarities of the effects of lactate and pyruvate on the uptake were correlated with the partial divergence of the pathways of gluconeogenesis from these precursors. The linkage of the weak organic acid uptake with gluconeogenesis is interpreted in terms of the hypothesis that the uptake is controlled by the cytoplasmic pyridine nucleotide redox potential, which is maintained with the participation of certain processes involved in glucose synthesis.

Direct and indirect stimulations of cyclic AMP formation in human brain.

1. Adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation, by use of an [3H]-adenine prelabelling assay, was measured in fragments of human cerebral cortex, taken in the course of various neurosurgical procedures. 2. Large accumulations of [3H]-cyclic AMP due to isoprenaline, noradrenaline and adenosine and small effects due to forskolin were observed. Histamine, 5-hydroxytryptamine (5-HT) and the excitatory amino acids glutamate and quisqualate were ineffective. 3. The response to noradrenaline consisted of two components; a direct beta-adrenoceptor response and an enhancement mediated by an alpha-adrenoceptor which appears to be similar to that in rat cerebral cortex. 4. The response to isoprenaline was also potentiated by histamine H1 receptor stimulation but the direct effect of 2-chloroadenosine was not altered by histamine, 5-HT or quisqualate. 5. It is concluded that some, but not all, of the indirect modulations of cyclic AMP formation previously observed in experimental animal brain exist in human cerebral cortex.

Secretory organelles of Paramecium cells (trichocysts) are not remarkably acidic compartments.

Acridine orange (AO) trapping in conjunction with fluorescence microscopy was applied to Paramecium cells. Trichocysts were not labeled when analyzed with an image intensification system (as opposed to a lysosomal population). Only with increasing intensity of ultraviolet light (UV) did trichocysts (and to some extent the cytosol) exhibit orange fluorescence, both effects being paralleled by increasing cell damage. Therefore, in comparison with the reported cytosolic pH (6.8), trichocysts cannot be considered as essentially acidic compartments. This is supported by experiments in vitro, using isolated cortex fragments or isolated fractions of membrane-bounded trichocysts (greater than or equal to 90% non-leaky). Again, during UV illumination orange fluorescence was observed even in the absence of ATP and Mg2+. Furthermore, this AO fluorescence and the condensation state of trichocyst contents were not affected by NH3 or by any of the widely differing ion- and H(+)-exchange inhibitors or ionophores tested. Decondensation of trichocyst contents occurred only when Ca2+ ionophore A23187 or X537A was incorporated into trichocyst membranes and when Ca2+ was then added. In this case all trichocysts partially decondensed within their intact membranes. We conclude that AO might be trapped in trichocysts by the abundant acidic secretory components during observation with UV light, rather than by acidic luminal pH.

Uptake of n-butyl-β-carboline-3-carboxylate by rat cerebral cortex

Abstract The existence of transport of butyl-β-carboline-3-carboxylate (βCCB) into rat cerebral cortex was examined in vitro . Accumulation of βCCB was observed within fragments of rat cerebral cortex at 37°C, reaching levels of 9200 pmol βCCB/mg of protein in 30 min. In crude synaptosomal fraction the uptake was rapid, reaching equilibration after 2 min. Kinetic analyses demonstrated that the mechanism was saturable with an estimated K M of 30 μM and a maximum influx of 2680 pmol/mg of protein/min. The transported material was accumulated inside the synaptosomal vesicles and was identified as βCCB by HPLC. Under our experimental conditions the βCCB uptake was not Na + -dependent. The cellular uptake of βCCB in brain tissue supports the hypothesis that this molecule may play a functional role in the brain.

N-ethylmaleimide-sensitive protein(s) involved in cortical exocytosis in the sea urchin egg: localization to both cortical vesicles and plasma membrane

The exocytotic release of secretory products from fragments of sea urchin egg cortex has been shown to be inhibited by covalent modification of membrane sulfhydryl groups with N-ethylmaleimide (NEM). Exocytotically competent preparations of reconstituted cortex, formed by recombination of purified cortical vesicles (CVs) with fragments of egg plasma membrane (PM) were also inhibited by treatment with NEM. The cellular localization of sulfhydryl-containing constituent(s) responsible for inhibition was investigated by treating CVs and/or PM with NEM prior to reconstitution. Both native cortex and cortex reconstituted with NEM-treated components were challenged with calcium-containing buffers. Exocytosis was monitored by phase-contrast microscopy, and quantitated by light scattering. Evidence for CV-PM fusion was obtained with an immunofluorescence-based assay that permits visualization of the transport of CV content proteins across the PM. Cortex reconstituted by recombination of NEM-treated CVs with untreated PM or by recombination of untreated CVs with NEM-treated PM was exocytotically competent, whereas cortex formed by recombination of NEM-treated CVs with NEM-treated PM was inactive. These results: (1) support the hypothesis that the mechanism of exocytosis in native and reconstituted cortex is the same; (2) provide evidence that both CV and plasma membranes participate in the release of CV contents from reconstituted cortex; and (3) suggest that sulfhydryl-containing protein(s) present on the surface of purified CVs and plasma membrane are involved in exocytosis.

Transplantation of the pineal gland in the mammalian third cerebral ventricle

Fine structural correlates and functional parameters were measured in pinealectomized rats following grafting of the pineal gland into the third cerebral ventricle. Pinealectomy caused a significant decrease in serum melatonin concentration of animals compared to that in normal controls. No significant difference was observed in the serum melatonin concentration between pinealectomized rats and those receiving sham transplantation with fragments of occipital cortex. By 6 weeks nearly 50% of pinealectomized rats receiving pineal transplants demonstrated a significant increase in the serum melatonin concentration in contrast to that of pinealectomized rats and pinealectomized animals receiving sham transplants. Pinealocytes survived and flourished following transplantation from the epithalamic region to the third cerebral ventricle of the hypothalamus in host rats. These cells were found to be arranged individually or in clusters surrounding fenestrated capillaries of the graft. Moreover, these pinealocytes demonstrated ultrastructural features indicative of an active secretory process, including densecore and clear vesicles as well as vacuoles containing flocculent material. Additional characteristics distinctive of normal control pinealocytes were observed in surviving cells of grafts, such as synaptic ribbons, synaptic ribbon fields, and myeloid bodies. Bundles of unmyelinated axons and apparent adrenergic nerve endings were observed with transmission electron microscopy and immunocystochemistry using antisera against tyrosine hydroxylase (TH). Nerve fibers and terminals were found within perivascular spaces surrounding fenestrated capillaries of viable grafts. These reported observations suggest that a significant population of transplanted pinealocytes recover functional activity (e.g., heightened melatonin secretion) following stereotaxic grafting into the third cerebral ventricles of pinealectomized animals. This apparent recovery of function may be linked directly to reinnervation of the gland by nerve fibers that appear to arise from the underlying median eminence.

Purification of the surface membrane-cytoskeleton complex (Cortex) of Paramecium and identification of several of its protein constituents

In ciliates, the major morphogenetic events take place in the cortex, a complex of membranes and closely associated filamentous networks. To analyze the problems of assembly and morphogenesis at the molecular level in Paramecium, we have developed a method of purification of cortex fragments which retain their in situ organization and display a highly reproducible electrophoretic profile. The method used either a four-step sucrose gradient yielding a cortex + oral apparatus fraction or a six-step gradient which allowed the cortex fragments to be freed from the oral apparatuses (which were recovered separately). By comparative electrophoresis and immunological probing of these and other cell fractions or purified organelles, we could identify several of the major polypeptides resolved by SDS PAGE as components of specific cortical or oral structures. The purification method was successfully applied to morphological mutants, and the first case of a mutational modification of a cortical polypeptide was observed.

Isolation and primary culture of rat renal cortical epithelial cells

Methods are described for the isolation of rat renal cortical epithelial cells by a collagenase and hyaluronidase perfusion, followed by pressing fragments of renal cortex through an 80-mesh screen and further enzymatic dissociation in vitro. Primary monolayer cultures are derived from the resulting suspension of tubular fragments and cells. Fibroblast and endothelial cell overgrowth is suppressed by the use of medium lacking arginine and containingd-valine in place ofl-valine. Further separation of fibroblasts from epithelial cells is achieved by a technique that takes advantage of the differential rate of attachment of the two cell types. The presence of glomerular cells in the cultures is diminished by a complete medium change 48 h after plating the cells.

Embolism of cerebral tissue to lungs

Two patients with head injury and pulmonary emboli of brain tissue are described. Both patients developed persistent bleeding with elevations of prothrombin time, partial thromboplastin time, and decreased platelet counts. Postmortem examination identified multiple skull fractures, subdural and subarachnoid blood, cortical tears, and intraparenchymal hemorrhages. Lacerations of dural venous sinuses were documented in each case. Multiple pulmonary arteries contained plugs of cerebral tissue, including fragments of cerebral and cerebellar cortex, and white matter. The literature concerning brain tissue emboli is reviewed. In neonates, three patients who survived longer than 1 hour were found to have evidence of persistent hemorrhage. Among both children and adults, our two cases are the only ones reported with associated clotting abnormalities. Brain tissue embolism in neonates occurs after difficult vaginal deliveries, often in conjunction with the use of forceps. Tears of the tentorium cerebelli or falx cerebri have been documented at postmortem examination in the majority of these cases. By contrast, brain tissue embolism in children and adults occurs in association with severe closed or penetrating head injury. In several cases, as in the two reported here, postmortem examination has demonstrated a large cerebral venous defect as the probable site of entry of brain tissue into the systemic circulation. (Neurosurgery 23:511-516, 1988)

Embolism of Cerebral Tissue to Lungs: Report of Two Cases and Review of the Literature

Two patients with head injury and pulmonary emboli of brain tissue are described. Both patients developed persistent bleeding with elevations of prothrombin time, partial thromboplastin time, and decreased platelet counts. Postmortem examination identified multiple skull fractures, subdural and subarachnoid blood, cortical tears, and intraparenchymal hemorrhages. Lacerations of dural venous sinuses were documented in each case. Multiple pulmonary arteries contained plugs of cerebral tissue, including fragments of cerebral and cerebellar cortex, and white matter. The literature concerning brain tissue emboli is reviewed. In neonates, three patients who survived longer than 1 hour were found to have evidence of persistent hemorrhage. Among both children and adults, our two cases are the only ones reported with associated clotting abnormalities. Brain tissue embolism in neonates occurs after difficult vaginal deliveries, often in conjunction with the use of forceps. Tears of the tentorium cerebelli or falx cerebri have been documented at postmortem examination in the majority of these cases. By contrast, brain tissue embolism in children and adults occurs in association with severe closed or penetrating head injury. In several cases, as in the two reported here, postmortem examination has demonstrated a large cerebral venous defect as the probable site of entry of brain tissue into the systemic circulation.

Differential distribution of the 5-α-reductase in the central nervous system of the rat and the mouse: Are the white matter structures of the brain target tissue for testosterone action?

In the brain of several animal species testosterone is converted into a series of 5-α-reduced metabolites, and especially into 17-β-hydroxy-5-α-androstan-3-one (DHT), by the action of the enzyme 5-α-reductase. The formation of DHT has never been evaluated in the white matter structures of the brain, which are composed mainly of myelinated axons. The experiements here described were performed in order to study, in the rat and the mouse, the DHT forming activity of several white matter structures, in comparison with that of the cerebral cortex and of the hypothalamus. Two sampling techniques were used in the rat: (1) microdissection under a stereo-microscope from frozen brain sections of fragments of corpus callosum, optic chiasm and cerebral cortex; (2) fresh tissue macrodissection of subcortical white matter, cerebral cortex and hypothalamus. Only macrodissection was used in the mice. The data show that, independently from the sampling technique used, there are considerable quantitative differences in the distribution pattern of the 5-α-reductase activity within different brain structures. Both in the rat and in the mouse, the enzyme appears to be present in higher concentrations in the white matter structures, than in the cerebral cortex and in the hypothalamus. The present results clearly show that the subcortical white matter and the corpus callosum are at least three times as potent as the cerebral cortex in converting testosterone into DHT. An even higher 5-α-reductase activity has been found in the optic chiasm. Further work is needed in order to understand the possible physiological role of DHT formation in the white matter structures.

A quantitative relationship between Cl − enhanced [ 3H]flunitrazepam and [formula omitted] binding to the benzodiazepine/GABA receptor chloride ionophore complex

A quantitative relationship between the efficacy (i.e. maximum enhancement) of Cl − to increase [ 3H]flunitrazepam binding and the density of [ 35S] -t- butylbicyclophosphorothionate binding sites was observed in well-washed membrane fragments of rat cerebral cortex previously exposed to phospholipase A 2. This relationship (described by the equation y = AB x ) was maintained when [ 3H]flunitrazepam was assayed at Cl − concentrations between 100 and 600 mM, and was not qualitatively altered by the presence of 100 μM pentobarbital. However, under experimental conditions that reduced the ratio of [ 35S]TBPS binding sites/benzodiazepine receptors, the effects of pentobarbital suggest that the conductance state of benzodiazepine receptor-coupled chloride channels may be the primary determinant of Cl − enhanced [ 3H]flunitrazepam binding.

Effect of vitamin D deficiency on the composition and in vitro labeling of rat kidney proteins

Densitometric analysis of single-dimension gels consistently demonstrated that, in addition to rat renal calcium binding protein (CaBP) ( M r 28,000), two other kidney proteins of M r 16,500 and M r 18,000 were significantly enriched in their contents in the vitamin D-replete rat. Partial characterization of the M r 18,000 and 16,500 proteins revealed that these proteins were heat-stable and distinct from calmodulin, as determined by their inability to undergo the calcium-dependent mobility shift in sodium dodecyl sulfate gels which is characteristic of calmodulin. The M r 16,500 and M r 18,000 kidney proteins did not cross-react with rat renal or rat intestinal CaBP antisera, as assessed by radioimmunoassay and Western blot analysis. A comparison of peptide maps of tryptic digests of these proteins and purified rat renal CaBP, as analyzed by high-pressure liquid chromatography, revealed no apparent homology. Protein synthesis studies using [ 35S]methionine and short-term tissue culture of kidney cortex fragments indicated that the most pronounced effect of vitamin D or 1,25 dihydroxyvitamin D 3 was increased synthesis of the M r 28,000 protein (3.2- to 4.6-fold increase compared to -D rats, P < 0.001). Synthesis of a M r 54,500 protein increased by 1.3- to 1.5-fold ( P < 0.05) and [ 35S]methionine incorporation into a M r 66,000 protein decreased by 1.2- to 1.3-fold ( P < 0.05) in +D rats. This study represents the first detailed characterization of the effects of vitamin D on the composition and synthesis of rat kidney proteins. The data indicate that the most significant effect of vitamin D on kidney proteins is increased synthesis of the M r 28,000 CaBP, suggesting that a major role of vitamin D in renal function is regulation of calcium transport at the distal tubule. However, dietary vitamin D or 1,25(OH) 2D 3 can influence the expression as well as the suppression of other specific kidney proteins.

Square-array fiber cell membranes in the mammalian lens

Two types of intercellular contacts have been observed between lens fiber cells. Gap junctions showing the normal EF-pit/PF-particle fracture pattern have been Identified in a number of species and predominate in the chick where they can cover as much as 50% of the cell surfaces. A second type of junction appears in mammalian lenses and is composed of membranes containing square crystalline arrays. In an effort to further characterize the square array membranes we have compared fragments of intact lenses to isolated junctions and used a variety of freeze-fractureetch procedures to visualize the unusual fracture morphology.Fig. 1A shows a typical fracture pattern of fiber cell membranes in a fragment of intact rat lens cortex. Two fracture surfaces are observed separated by a large step (arrows). The upper surface is covered by large irregularly shaped particles. In the lower membrane surface 8-9 nm dia. particles are clustered in some regions into small square arrays; a few tightly packed clusters appear to be covered by a small plaque of amorphous material (circles).

Cyclic assembly-disassembly of cortical microtubules during maturation and early development of starfish oocytes

An extensive array of cortical microtubules in oocytes of the starfish Pisaster ochraceus undergoes multiple cycles of disappearance and reapparance during maturation and early development. These events were studied in isolated fragments of the oocyte cortex stained with antitubulin antibodies for indirect immunofluorescence. The meshwork of long microtubules is present in the cortex (a) of immature oocytes, i.e., before treatment with the maturation-inducing hormone 1-methyladenine, (b) for 10–20 min after treatment with 1-methyladenine, (c) after formation of the second polar body (in reduced numbers in unfertilized oocytes), and (d) in the intermitotic period between first and second cleavage divisions. The array of cortical microtubules is absent in oocytes (a) undergoing germinal vesicle breakdown, (b) during the two meiotic divisions (polar body divisions), and (c) during mitosis of the first and, perhaps, subsequent cleavage divisions. The cycle of assembly-disassembly of cortical microtubules is synchronized to the cycle of nuclear envelope breakdown and reformation and to the mitotic cycle; specifically, cortical microtubules are present when a nucleus is intact (germinal vesicle, female pronucleus, zygote nucleus, blastomere nucleus) and are absent whenever a meiotic or mitotic spindle is present. These findings are discussed in terms of microtubule organizing centers in eggs, possible triggers for microtubule assembly and disassembly, the eccentric location of the germinal vesicle, and the regulation of oocyte maturation and cell division.

Correlation of LH, FSH and GnRH release during various brain-pituitary coincubations.

Hemipituitaries and various brain fragments from female albino rats were coincubated in the presence or absence of veratrine (a depolarizing agent). The release of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and gonadotropin-releasing hormone (GnRH) was measured by radioimmunoassay. In the absence of veratrine, none of the brain fragments affected LH and FSH release. In the presence of veratrine, large increases in LH and FSH release were caused by medial basal hypothalamic (MBH) fragments, slight increases were caused by suprachiasmatic:preoptic area fragments, and cerebral cortex fragments had no effect. LH and FSH release caused by brain fragments was significantly correlated with GnRH release and the GnRH concentrations attained during coincubations could account for all increases in LH and FSH release observed. Also, GnRH antiserum completely blocked increases in LH and FSH release during MBH-hemipituitary coincubations. The data indicate that the rat brain is unlikely to contain neurohormones other than GnRH capable of directly stimulating LH and FSH release in vivo.