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The gravireceptor of Phycomyces. Its development following gravity exposure.

The gravitropism of a mature stage IV Phycomyces sporangiophore has a shorter and more uniform latency if the sporangiophore is exposed horizontally to gravity during its earlier development (stage II and stage III). This early exposure to an altered gravitational orientation causes the sporangiophore to develop a gravireceptor as it matures to stage IV and resumes elongation. A technique has been developed to observe the spatial relationship between the vacuole and the protoplasm of a living sporangiophore and to show the reorganization caused by this exposure to altered gravity. Possible gravireceptor mechanisms are discussed.

Cytoplasm↗

Evidence of root zone hypoxia in Brassica rapa L. grown in microgravity.

A series of experiments was conducted aboard the U.S. space shuttle and the Mir space station to evaluate microgravity-induced root zone hypoxia in rapid-cycling Brassica (Brassica rapa L.), using both root and foliar indicators of low-oxygen stress to the root zone. Root systems from two groups of plants 15 and 30 d after planting, grown in a phenolic foam nutrient delivery system on the shuttle (STS-87), were harvested and fixed for microscopy or frozen for enzyme assays immediately postflight or following a ground-based control. Activities of fermentative enzymes were measured as indicators of root zone hypoxia and metabolism. Following 16 d of microgravity, ADH (alcohol dehydrogenase) activity was increased in the spaceflight roots 47% and 475% in the 15-d-old and 30-d-old plants, respectively, relative to the ground control. Cytochemical localization showed ADH activity in only the root tips of the space-grown plants. Shoots from plants that were grown from seed in flight in a particulate medium on the Mir station were harvested at 13 d after planting and quick-frozen and stored in flight in a gaseous nitrogen freezer or chemically fixed in flight for subsequent microscopy. When compared to material from a high-fidelity ground control, concentrations of shoot sucrose and total soluble carbohydrate were significantly greater in the spaceflight treatment according to enzymatic carbohydrate analysis. Stereological analysis of micrographs of sections from leaf and cotyledon tissue fixed in flight and compared with ground controls indicated no changes in the volume of protoplast, cell wall, and intercellular space in parenchyma cells. Within the protoplasm, the volume occupied by starch was threefold higher in the spaceflight than in the ground control, with a concomitant decrease in vacuolar volume in the spaceflight treatment. Both induction of fermentative enzyme activity in roots and accumulation of carbohydrates in foliage have been repeatedly shown to occur in response to root zone oxygen deprivation. These results indicate that root zone hypoxia is a persistent challenge in spaceflight plant growth experiments and may be caused by microgravity-induced changes in fluid and gas distribution.

Alcohol Dehydrogenase↗

General physiology, experimental psychology, and evolutionism. Unicellular organisms as objects of psychophysiological research, 1877-1918.

This essay aims to shed new light on the relations between physiology and psychology in the late nineteenth and early twentieth centuries by focusing on the use of unicellular organisms as research objects during that period. Within the frameworks of evolutionism and monism advocated by Ernst Haeckel, protozoa were perceived as objects situated at the borders between organism and cell and individual and society. Scholars such as Max Verworn, Alfred Binet, and Herbert Spencer Jennings were provoked by these organisms to undertake experimental investigations situated between general physiology and psychology that differed from the physiological psychology advocated by Wilhelm Wundt. Some of these investigations sought to locate psychological properties in the molecular structure of protoplasm; others stressed the existence of organic and psychological individuality in protozoa. In the following decades, leading philosophers such as Friedrich Nietzsche, Charles Sanders Peirce, and Henri Bergson, as well as psychological researchers like Sigmund Freud, integrated the results of these investigations into their reflections on such problems as the nature of the will, the structure of the ego, and the holistic nature of the reactions of organisms to their environment.

Animals↗

Astroglial nitration after postnatal excitotoxic damage: correlation with nitric oxide sources, cytoskeletal, apoptotic and antioxidant proteins.

Oxygen free radicals and nitric oxide (NO) participate in the pathogenesis of acute central nervous system (CNS) injury by forming peroxynitrite, which promotes oxidative damage and tyrosine nitration. Neuronal nitration is associated with cell death, but little is known of the characteristics and cell fate of nitrated astrocytes. In this study, we have used a postnatal excitotoxic lesion model (intracortical NMDA injection) and our aims were (i) to evaluate the temporal and spatial pattern of astroglial nitration in correlation with the neuropathological process and the sources of NO; and (ii) to establish, if any, the correlation among astrocyte nitration and other events such as expression of cytoskeletal proteins, antioxidant enzymes, and cell death markers to cope with nitration and/or undergo cell death. Our results show that after postnatal excitotoxic damage two distinct waves of nitration were observed in relation to astrocytes. At 24 h post-lesion, early-nitrated astrocytes were found within the neurodegenerating area, coinciding with the time of maximal cell death. These early-nitrated astrocytes are highly ramified protoplasmic cells, showing diffuse glial fibrillary acidic protein (GFAP) content and expressing inducible NOS. At later time-points, when astrogliosis is morphologically evident, nitrated hypertrophied reactive astrocytes are observed in the penumbra and the neurodegenerated area, displaying increased expression of GFAP and vimentin cytoskeletal proteins and of metallothionein I-II and Cu/Zn superoxide dismutase antioxidant proteins. Moreover, despite revealing activated caspase-3, they do not show TUNEL labeling. In summary, we show that nitrated astrocytes in vivo constitute a subpopulation of highly reactive astrocytes which display high resistance towards oxidative stress induced cell death.

Animals↗

Nasogastric hyperalimentation through a polyethylene catheter: an alternative to central venous hyperalimentation.

We performed nasogastric hyperalimentation with polyethylene catheters and appropriate feeding solutions in 12 cachectic patients who had been referred as candidates for central venous hyperalimentation. Most patients had primary gastrointestinal disease. The duration of hyperalimentation averaged 31 days. Seven patients obtained rapid weight gain (average 0.3 kg/day) with the nasogastric hyperalimentation alone. An additional two were successfully repleted with the addition of parenteral fluids via peripheral veins. In the nine repleted patients, serum albumin rose by average 19%, 24-hr urine creatinine by average 21%, and triceps skinfold by average 46%. The nature of the weight gain in the nine successful cases was analyzed by the metabolic balance study technique. Average composition of the increment in weight was: 50% protoplasm, 48% extracellular fluid, 19% adipose tissue, and less than 1% bone. We conclude that nasogastric hyperalimentation can replace central venous hyperalimentation in a substantial proportion of patients now receiving the latter type of treatment.

Adult↗

Effects of cigarette smoke condensate and 12-O-tetradecanoylphorbol-13-acetate on gap junction structure and function in cultured cells.

The effects of cigarette smoke condensate (CSC) and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on gap junction structure, quantity and function were investigated. Gap junction morphology was studied in rotary-shadowed freeze-fracture replicas of primary chick embryo hepatocytes. CSC (24 micrograms/ml) induced a strong decrease of gap junction areas; within 6 h the areas were reduced by greater than 60%. In the first 3 h of exposure, TPA (100 ng/ml) also reduced gap junction areas, but in the next 3 h a partial recovery was observed. Protoplasmic fracture face centre-to-centre particle spacings were used as a measure for gap junction coupling. CSC had a slow (although not significant) reducing effect on particle spacings, while TPA induced a reduction from 10.6 nm (control) to 10.0 nm within 3 h, indicating a reduction of coupling. Gap junctions were quantified in thin sections of cultured chick embryo hepatocytes, V79 fibroblasts, and co-cultivated hepatocytes and V79 cells. CSC did not influence gap junction numbers in any of these cultures, while TPA treatment caused a disappearance of gap junctions between hepatocytes and between hepatocytes and V79 cells in the first 12 h of cultivation. In the following 36 h a slow recovery could be observed. Gap junctions between V79 cells had already disappeared within 30 min. Metabolic co-operation between hepatocytes and hypoxanthine-guanine phosphoribosyltransferase-deficient V79 cells was quickly and continuously blocked by CSC over 27 h, whereas the phorbol ester induced a transient block. The dissimilar effects of these compounds on both gap junction structure and function indicate that they act via different mechanisms. The finding that CSC did not inhibit phorbol ester protein kinase C binding and did not activate this protein kinase in vitro supports this hypothesis.

Animals↗

Identification of proteins downregulated during the postnatal development of the cat visual cortex.

To identify proteins that play a role in the development of the mammalian visual cortex, we have used an immunosuppression and rapid immunization strategy to generate monoclonal antibodies to antigens that are present in area 17 of the cat during the peak of cortical plasticity but are downregulated near the end of the plastic period. We report here the immunohistochemical and immunobiochemical characterization of six monoclonal antibodies that identify antigens preferentially expressed in the cat visual cortex at 5 weeks of age. Monoclonal antibodies Cat-305 and Cat-306 detect three immunoreactive elements that are not present at birth but are present at 5 weeks. The majority of immunoreactivity is associated with a population of cells in the white matter that are absent at 15 weeks of age. At both 5 and 15 weeks, a very small number of neurons show intense immunoreactivity throughout all processes, resembling that achieved with a Golgi stain. In addition, a diffuse band of immunoreactivity in layer IV is largely restricted to cortical areas 17 and 18. Cat-307 recognizes a 150 kDa soluble protein present in small cytoplasmic inclusions. These cytoplasmic "dot" are present in all layers, but are most prominent in layer V. Cat-307 immunoreactivity is present at birth and is completely downregulated by 15 weeks. Cat-104 and Cat-105 recognize a 200 kDa insoluble protein present at birth and at 5 weeks, but markedly downregulated by 15 weeks. At birth, the white matter, subplate, and layer I are most densely labeled, while at 5 weeks labeling is densest in layers II, III, and V. Cat-402 recognizes a number of high-molecular-weight antigens that are differentially expressed at 5 and 15 weeks of age. Stained non-neuronal cells that resemble protoplasmic astrocytes are present in all layers at both 5 and 15 weeks. At 5 weeks, but not at birth or 15 weeks, darkly immunoreactive radial processes are observed that run through the full depth of the cortex. We show here that immunoreactivity for several different monoclonal antibodies is detected selectively during the period of maximal developmental plasticity. The results demonstrate that the cat visual cortex at 5 weeks of age is molecularly distinct from the cortex at 15 weeks.

Animals↗

Differential expression of D1 and D5 dopamine receptors in the fetal primate cerebral wall.

Previous film autoradiographic studies demonstrated that, during corticogenesis, dopamine receptors of the D1 class are abundant in the embryonic primate cerebral wall. In the present study, we expand these findings by identifying the cellular elements of the fetal occipital cerebral wall expressing D1 and D5 subtypes of the D1 dopamine receptor class. We have examined tissue from monkey fetuses collected at 70, 90 and 120 days of gestation using antibodies directed against C-termini of the D1 and D5 dopamine receptors. At all three embryonic ages studied, we found D1 and D5 receptors expressed by multiple cell types of the embryonic cerebral wall. Both D1 and D5 receptor proteins are produced by pyramidal neurons of the cortical plate and by a variety of interstitial neurons of the subplate and intermediate zones. D1 and D5 receptors are also present in cells of the proliferative ventricular and subventricular zones, some of which were identified as dividing cells. In addition, D1 and D5 receptors are detectable in the protoplasmic astroglial and ependymal cells distinguishable in monkey fetuses collected at 120 days of gestation. Some cellular elements of the embryonic monkey cerebral wall express only one subtype of the D1 dopamine receptor class. For example, embryonic Cajal-Retzius neurons in the marginal zone and migrating neurons in the intermediate zone are immunoreactive only to D5 antisera. In contrast, radial glia can be labeled only with D1 receptor-specific antisera. Finally, only D1 receptors are detectable in the blood vessels penetrating the embryonic monkey cerebral wall. Based on these observations, we propose that dopamine receptors of the D1 class play an important role in regulating cerebral cortical formation and that D1 and D5 receptor subtypes may participate in regulation of different aspects of this process.

Animals↗

Isolation of antigenic components from the Lyme disease spirochete: their role in early diagnosis.

Patients with early Lyme disease produce IgM antibodies to a 41,000-dalton polypeptide of Borrelia burgdorferi. With advancing disease, IgG antibodies recognize a larger number of spirochetal polypeptides. Sodium dodecyl sulfate treatment of spirochetes at a concentration of 0.03% resulted in an outer envelope (OE) fraction in the supernatant and a protoplasmic cylinder (PC) flagellar fraction in the pellet. Shearing of the PC pellet followed by ultrafiltration and dialysis resulted in a flagellin-enriched fraction. From the OE and flagellin-rich fractions, individual polypeptides with Mr of 66,000, 41,000, and 31,000/34,000 daltons were eluted in microgram quantities after electrophoresis. The flagellin-enriched fraction as well as the eluted polypeptides were used as antigens in the ELISA. The flagellin-enriched fraction was superior to the standard ELISA antigen. The 41-kilodalton (kDa) flagellin antigen was not useful. Antigens of 66 kDa and 31/34 kDa were confirmed to be part of the late antibody response.

Antibodies, Bacterial↗

Proteases during the growth of Ehrlich ascites tumor. II. The kallikrein-kinin system.

Ascitic fluid and ascites tumor cells from Swiss mice bearing Ehrlich ascites tumor were assayed for components of the kallikrein-kinin system at various times during tumor growth. Changes in component levels were correlated with those in the plasma. Ascitic fluid contained an acetone-activated prekallikrein that increased in concentration during tumor growth and reached peak levels during the 7th-10th day post transplant. No free kinin activity was present in the ascitic fluid. During tumor growth, kininogen levels increased in parallel with prekallikrein levels. The ascitic fluid also contained a kinin-destroying activity that was initially high during the early phase of tumor growth. Tumor cell fractions, prepared by ultracentrifugal techniques, had no kinin-forming activity while possessing kinin-destroying activity that was localized in the soluble protoplasmic protein and nuclear fractions. The kinin-forming activity of the ascitic fluid resembled that of the plasma with respect to pH optima, kinetics of kinin formation, and effect of protease inhibitors. The kininase activity of both ascitic fluid and plasma differed from that of the tumor cell fractions.

Animals↗

Is intracellular ice formation the cause of death of mouse sperm frozen at high cooling rates?

Mouse spermatozoa in 18% raffinose and 3.8% Oxyrase in 0.25 x PBS exhibit high motilities when frozen to -70 degrees C at 20-130 degrees C/min and then rapidly warmed. However, survival is <10% when they are frozen at 260 or 530 degrees C/min, presumably because, at those high rates, intracellular water cannot leave rapidly enough to prevent extensive supercooling and this supercooling leads to nucleation and freezing in situ (intracellular ice formation [IIF]). The probability of IIF as a function of cooling rate can be computed by coupled differential equations that describe the extent of the loss of cell water during freezing and from knowledge of the temperature at which the supercooled protoplasm of the cell can nucleate. Calculation of the kinetics of dehydration requires values for the hydraulic conductivity (Lp) of the cell and for its activation energy (Ea). Using literature values for these parameters in mouse sperm, we calculated curves of water volume versus temperature for four cooling rates between 250 and 2000 degrees C/min. The intracellular nucleation temperature was inferred to be -20 degrees C or above based on the greatly reduced motilities of sperm that underwent rapid cooling to a minimum temperature of between -20 and -70 degrees C. Combining that information regarding nucleation temperature with the computed dehydration curves leads to the conclusion that intracellular freezing should occur only in cells that are cooled at 2000 degrees C/min and not in cells that are cooled at 250-1000 degrees C/min. The calculated rate of 2000 degrees C/min for IIF is approximately eightfold higher than the experimentally inferred value of 260 degrees C/min. Possible reasons for the discrepancy are discussed.

Algorithms↗

The functional significance of brain metallothioneins.

Metallothioneins (MTs) are ubiquitous low molecular weight proteins characterized by their abundant content of cysteines. Two MT isoforms, MT-I and MT-II, are expressed coordinately in all mammalian tissues. In the CNS, MT-I and MT-II are conspicuously absent from neuronal populations, yet abundant in fibrous and protoplasmic astrocytes. A newly identified brain-specific MT gene, MT-III, is predominantly expressed in zinc-containing neurons of the hippocampus and absent from glial elements. MTs have been implicated as regulator molecules in gene expression, homeostatic control of cellular metabolism of metals, and cellular adaptation to stress. MTs store and release essential metals, such as zinc and copper, maintaining the low intracellular concentration of free essential metals. Thus, MTs fulfill a regulatory capacity and influence transcription, replication, protein synthesis, metabolism, as well as other zinc-dependent biological processes. Because MT-III is particularly abundant in zinc-containing neurons of the hippocampus, it is likely to play an important role in neuromodulation by zinc-containing neurons and to act as a sink for free zinc. It may also play an etiologic role in various pathophysiological conditions associated with increased extracellular zinc. Studies demonstrating that MT-III prevents neuronal sprouting in vitro, appears to be down-regulated in Alzheimer's disease, and that MT-III "knockout" mice appear highly sensitive to kainateinduced seizures have focused growing attention on the etiologic role of MT-III in neurodegeneration.-Aschner, M. The functional significance of brain metallothioneins.

Alzheimer Disease↗

A distinctive glioneuronal tumor of the adult cerebrum with neuropil-like (including "rosetted") islands: report of 4 cases.

Four examples of a novel glioneuronal neoplasm are presented. All tumors affected adults (including two males and two females aged 25-40 years) as supratentorial, cerebral hemispheric masses with associated seizure activity and, in one case, symptoms of raised intracranial pressure and progressive hemiparesis. CT scans in two cases revealed hypodense masses without calcification. MRI scans at presentation demonstrated, in all cases, solid T1-hypointense and T2-hyperintense tumors with mass effect in one instance but no edema or contrast enhancement. Only one was relatively circumscribed on neuroradiologic study. All were infiltrative in their histologic growth pattern and predominantly glial in appearance, being composed mainly of fibrillary, gemistocytic, or protoplasmic astroglial elements of WHO grade II to III. Their distinguishing feature was their content of sharply delimited, neuropil-like islands of intense synaptophysin reactivity inhabited and rimmed in rosetted fashion by cells demonstrating strong nuclear immunolabeling for the neuronal antigens NeuN and Hu. These cells included small, oligodendrocyte-like ("neurocytic") elements as well as larger, more pleomorphic forms. Two cases contained, in addition, well-differentiated neurons of medium to ganglion-cell size. Proliferative activity was observed principally within the glial compartment; two cases contained mitotic figures and exhibited relatively elevated MIB-1 indices (6.8% and 8.2%). One of the latter progressed and proved fatal at 30 months following subtotal resection and radiotherapy. The three other patients are alive at intervals of 14 to 83 months, two tumor-free and one with extensive disease associated with the appearance of enhancement on MRI. This glioneuronal tumor variant may pursue an unfavorable clinical course.

Adult↗

Denervation microangiopathy in senile dementia, Alzheimer type.

Structural analysis of the capillary plexus in the brains of 5 patients with clinical and neuropathological diagnosis of Senile Dementia, Alzheimer Type, revealed a group of striking physical alterations compared with tissue specimens from 5 age-matched controls. Capillary walls were thickened with irregular lumpy, nodulated contours which appeared due, in part, to infiltration of the vascular wall with rounded cell-like bodies. In some cases, these resembled the perikarya of pericytes or monocytes, or their protoplasmic extensions, which were often filled with lipids. In each case, there was no trace of the perivascular neural plexus which regularly invests the microvasculature of the brain parenchyma. The loss of this neural plexus, believed to originate largely from locus ceruleus and the basal forebrain, may be related to the changes in capillary wall structure, and these, in turn, may lead to profound alterations in blood-brain barrier function. We suggest that this subcortically induced denervation microangiopathy may serve as a pathogenic factor in the development of SDAT.

Aged↗

Cellular localization of messenger RNA encoding amyloid-beta-protein in normal tissue and in Alzheimer disease.

Amyloid precursor protein (APP) gene encodes the short peptide fragment amyloid-beta-protein present in senile plaque cores, cerebrovascular amyloid, and intracellular neurofibrillary tangles in Alzheimer disease (AD). Using in situ hybridization with biotin-labeled RNA probes, we found distinctive patterns of APP gene expression in different regions of postmortem human brain. Strong hybridization signal for APP messenger RNA (mRNA) was detected in specific classes of neurons, fascicular oligodendroglia, satellite glia, and presumptive microglia. Weaker signal was seen in other neuronal classes, fascicular astrocytes, and vascular endothelial cells, but no signal was seen in protoplasmic astrocytes. Human thymus also shows a restricted pattern of hybridization with high signal in reticular epithelial cells, and much lower signal in lymphocytes. In AD patients, neuronal hybridization for APP mRNA was specifically increased in hippocampus, but not cerebellar and visual cortex when compared to hybridization for neuron-specific enolase mRNA. Most neurons with neurofibrillary tangles had strong APP mRNA signal. These results suggest that APP gene expression is highly regulated in normal tissue, that many different cell classes in brain express the APP gene, and that neuronal expression may increase specifically in brain regions where widespread injury occurs in AD. Amyloid deposits in brains of AD patients might be explained by local production of precursor protein in endothelial cells, neurons or glia.

Aged↗

The induction of intractranial neoplasms by the inoculation of avian sarcoma virus in perinatal and adult rats.

The induction of intracranial neoplasms following the intracerebral inoculation of avian sarcoma virus (ASV) in neonatal mammals is well established. The present study demonstrates the susceptibility of adult rats and compares the incidence and morphology of tumors induced by a uniform inoculum of the Bratislava-77 strain of ASV in adult, neonatal, and fetal Fischer 344 rats. Post-inoculation mortality varied significantly between groups inoculated at 1, 10 and 100 days and was most precipitous in perinatally inoculated rats. Percentage of tumor induction declined from 100% among rats inoculated at 1 day of age to 50% among rats inoculated at 100 days of age. The mean number of tumors/animal was inversely proportional to the logarithm of the age at inoculation. A large majority of tumors in each group were glial; the remainder were mesenchymal and mixed glial and mesenchymal. Neuroglial tumors included: mixed gliomas with oligodendroglial and astrocytic elements; and gemistocytic, pilocytic, fibrillary, anaplastic and protoplasmic astrocytomas. Tumors induced in perinates were more heterogeneous in histological pattern while tumors induced in perinates were more heterogeneous in histological pattern while tumors induced in older animals tended to be purely astrocytic and of uniform cell type. Mesenchymal tumors occurred primarily in the meninges and were common among animals inoculated perinatally but were rare among animals inoculated as adults. No neuronal tumors were encountered even among rats inoculated as early as 16 days of gestation.

Age Factors↗

Edema of the cortical gray matter of the human cerebrum.

Five cases of brain tumor are reported in which an extracellular edema of the cerebral cortex was recognized in the form of lakes of eosinophilic, PAS positive material, presumably serum proteins, permeating among the neuronal and glial cells and processes. In three, the astrocytes and their processes were stained in replicate paraffin sections by a gold sublimate technique. The astrocytic changes were variable. Most often, the astrocytes changed from protoplasmic to fibrillary, with long deeply stained processes, the cells sometimes becoming large and distorted. Many became enlarged and smudgy, with short stubby processes. Only a few showed the fragmentation and disintegration of processes. Only a few showed the fragmentation and disintegration of processes which are regularly observed in edematous white matter. The neuronal processes remained essentially normal. In comparison with edema of white matter, edema of the cortex is rare, involves only small portions of tissue, and differs in its effects on astrocytes. The edema in both cortex and white matter is extracellular. We have not been able to recognize a specific intracellular form of edema, grossly or with light microscopic techniques.

Aged↗

Cerebro-hepato-renal syndrome. Report of a case with histochemical and ultrastructural observations.

A new case of the cerebro-hepato-renal syndrome is being reported. The neuropathologic changes consisted of developmental abnormalities of cerebral and cerebellar cortex and of the inferior olives. In addition, there were metabolic changes in the central nervous system, indicated by an accumulation of lipid within histiocytes of free in gray and white matter, deficiency in myelination and gliosis of the white matter, and marked proliferation of protoplasmic astrocytes in the gray matter. A unique feature of this case was the presence of numerous clusters of lipid-filled macrophages and occasional cholesterol crystals in the molecular layer of the cerebellum. The histochemical reactions and ultrastructural appearances of the lipid deposits are suggestive of accumulation of several different types of lipids.

Abnormalities, Multiple↗