Response of striatal astrocytes to neuronal deafferentation: an immunocytochemical and ultrastructural study

This ultrastructural and light microscopic immunocytochemical study describes the time course of anatomical changes that occur in striatal astrocytes in response to neuronal deafferentation in young adult rats and the coordinate distribution of two astrocytic proteins involved in reactive synaptogenesis, glial fibrillary acidic protein and clusterin. We found that following a unilateral lesion of the cerebral cortex, striatal astrocytes undergo a rapid ultrastructural transformation from a protoplasmic to a reactive type of astroglia and are the primary cells involved in the removal of degenerating axon terminals, but not axons of passage, from the neuropil. In addition, at 10 and 27 days postlesion, processes of reactive astrocytes are also seen to occupy vacant postsynaptic spines after degenerating presynaptic terminals are removed, suggesting that they may also participate in the reinnervation of the deafferented neurons. By immunocytochemistry, reactive astrocytes were characterized by a significant increase in the intensity of glial fibrillary acidic protein staining beginning at three days postlesion and lasting for at least 27 days postlesion. Reactive astrocytes were characterized by cellular hypertrophy and an increase in the density of immunoreactive processes distributed throughout the deafferented striatum. However, our analysis of astrocyte cell number found no evidence of astrocyte proliferation in response to the deafferentation lesion. Although previous in situ hybridization studies have reported elevated clusterin messenger RNA in reactive astrocytes after decortication, clusterin immunoreactivity was not seen in the cell soma of reactive astrocytes but was distributed as punctate deposits, ranging from 1 to 2 microns in diameter, within the neuropil of the deafferented striatum. At 10 days postlesion, the distribution of clusterin staining appeared as large aggregates of immunoreactive deposits adjacent to neurons. However, by 27 days postlesion, the aggregates of clusterin reaction product were replaced by a fine scattering of individual punctate deposits distributed evenly over the dorsal part of the deafferented striatum. These data support the notion that reactive astrocytes serve multiple, time-dependent roles in response to brain injury and are involved in both the removal of degenerative debris from the lesion site as well as in reforming the synaptic circuitry of the damaged brain. Our data suggest that, in response to decortication, reactive astrocytes are the primary cells responsible for removing degenerating axon terminals, but not axons of passage, from the deafferented striatum and that the coordinate increase in glial fibrillary acidic protein may serve to stabilize the extension of reactive astrocytic processes during phagocytosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Study on preventive and curative effects of liu wei di huang tang on tumors

Liu Wei Di Huang Tang (LWDHT), a Chinese prescription for strengthening the body resistance, restoring the normal functions of the body to consolidate the constitution, and nourishing and invigorating the kidney yin, has been used to prevent and treat severe hyperplasia of esophageal epithelium for many years. The results of this experiment show that LWDHT can increase markedly the number of lymphocytes, mainly T lymphocytes, in tumor-bearing mice. Free-flow electrophoresis shows that in tumor-bearing mice the electrophoretic characteristics of T lymphocytes are changed, i.e., reduction of the number of T lymphocytes with a higher electrophoretic rate, but LWDHT can alleviate this disorder. Study on the cell membrane fluidity of carcinoma cells in EAC mice demonstrates that LWDHT can decrease the cell membrane fluidity, suggesting that it can inhibit division of carcinoma cells.

Effects of colcemid concentration on chromosome aberration analysis in human lymphocytes

As a part of technical improvements of chromosome aberration analysis on human peripheral lymphocytes for biological radiation dosimetry, we examined the optimal conditions for the use of colcemid in chromosome preparation in order to obtain enough number of cells at metaphase in the first cell division. When treated with colcemid at concentrations below 0.01 microgram/ml from the beginning of culture, cultures harvested at 48 hours had low mitotic indices. Colcemid treatment at 0.025 to 0.05 microgram/ml during 48 hours resulted in high mitotic indices (8 to 15%) and almost of the mitotic cells remaining in the 1st cell division, suggesting that this range of colcemid concentration was appropriate for continuous treatment with colcemid. We further examined the effect of colcemid concentration on the quantitative consistency of the yields of radiation-induced chromosome aberration. Repeated experiments showed that the yield of dicentrics and centric rings in the culture having colcemid at 0.025 microgram/ml concentration were larger than that at 0.05 microgram/ml. These data indicate the importance of assuring the accuracy of colcemid concentration in the lymphocyte culture for cytogenetic radiation dosimetry.

On the complexity of multiple sequence alignment

We study the computational complexity of two popular problems in multiple sequence alignment: multiple alignment with SP-score and multiple tree alignment. It is shown that the first problem is NP-complete and the second is MAX SNP-hard. The complexity of tree alignment with a given phylogeny is also considered.

A digitized fluorescence imaging study of intracellular free calcium, mitochondrial integrity and cytotoxicity in rat renal cells exposed to ionomycin, a calcium ionophore

The objective of this study was to explore the role of extracellular Ca2+ and mitochondrial integrity in ionomycin-induced cytotoxicity in primary cultures of rat kidney cortical epithelial cells using digitized fluorescence imaging (DFI), which is a powerful tool for continuously observing the dynamic intracellular biochemistry of single living cells. Using DFI, intracellular free calcium ion concentration ([Ca2+]i), mitochondrial membrane potential and loss of cell viability in individual rat renal cortical epithelial cells were examined temporally by fura-2, rhodamine 123 (Rh-123) and propidium iodide (PI), respectively. Images were taken within 10 min after exposure to 5 and 10 microM ionomycin. These three parameters, [Ca2+]i, mitochondrial membrane potential and cell viability, were also measured in populations of cells by a multiwell fluorescence scanner with fluo-3, Rh-123 and PI, respectively. Cytotoxicity was also assessed by two colorimetric cytotoxicity tests (LDH leakage and mitochondrial MTT reduction). Using DFI, the fluorescence scanner and the colorimetric cytotoxicity tests, we found that exposure of primary cultures of rat kidney cortical epithelial cells to high concentrations of ionomycin (5 and 10 microM) caused a rapid and sustained rise in [Ca2+]i, which preceded dissipation of the mitochondrial membrane potential and loss of cell viability and that chelation of extracellular Ca2+ with EGTA attenuated these responses. We demonstrated the value of using DFI to continuously observe the dynamic intracellular biochemistry of single living cells by establishing a sequence of elevated [Ca2+]i, dissipation of mitochondrial membrane potential and cytotoxicity. We conclude that a combination of the influx of extracellular Ca2+ and loss of mitochondrial integrity may be responsible for the cytotoxicity observed in individual renal cells and populations of renal cells after treatment with ionomycin.

Microbial models of mammalian metabolism: involvement of cytochrome P450 in the N-demethylation of N-methylcarbazole by Cunninghamella echinulata

1. As previously reported (Yang and Davis 1992), N-methylcarbazole (NMC) is converted to N-hydroxymethylcarbazole (NHMC), and 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), two relatively stable carbinolamine metabolites by the fungus Cunninghamella echinulata (ATCC 9244). Decomposition of these two carbinolamines yields the corresponding dealkylated metabolites, carbazole and 3-hydroxycarbazole. In the present study, the possible involvement of cytochrome P450 in the requisite N-alkyl hydroxylation reaction was examined. 2. Carbon monoxide, a classical P450 inhibitor, markedly inhibited the formation of NHMC, as did potassium cyanide. 1-Benzylimidazole, piperonyl butoxide and SKF-525A inhibited the formation of both NHMC and 3-OH-NHMC, while beta-naphthoflavone (5,6-benzoflavone) induced their formation. 3. The source of the oxygen atom in the metabolite NHMC was examined by GC/MS analysis of NHMC formed during incubation of NMC in H218O-enriched medium which resulted in no incorporation of labelled oxygen into the metabolite. 4. An intermolecular isotope effect was not observed for the formation of NHMC suggesting that C-H bond cleavage is not a rate limiting step in the formation of this metabolite under the conditions examined. 5. It was concluded that P450 enzymes may be involved in the N-demethylation of NMC catalyzed by this fungal model of mammalian metabolism, and provides further support for biochemical and mechanistic parallels between mammalian metabolism and microbial systems catalyzing phase-1 biotransformations.

Insertion and deletion mutations in the repA4 region of the IncFII plasmid NR1 cause unstable inheritance

Mutants of IncFII plasmid NR1 that have transposons inserted in the repA4 open reading frame (ORF) are not inherited stably. The repA4 ORF is located immediately downstream from the replication origin (ori). The repA4 coding region contains inverted-repeat sequences that are homologous to the terC inverted repeats located in the replication terminus of the Escherichia coli chromosome. The site of initiation of leading-strand synthesis for replication of NR1 is also located in repA4 near its 3' end. Transposon insertions between ori and the right-hand terC repeat resulted in plasmid instability, whereas transposon insertions farther downstream did not. Derivatives that contained a 35-bp frameshift insertion in the repA4 ORF were all stable, even when the frameshift was located very near the 5' end of the coding region. This finding indicates that repA4 does not specify a protein product that is essential for plasmid stability. Examination of mutants having a nest of deletions with endpoints in or near repA4 indicated that the 3' end of the repA4 coding region and the site of leading-strand initiation could be deleted without appreciable effect on plasmid stability. Deletion of the pemI and pemK genes, located farther downstream from repA4 and reported to affect plasmid stability, also had no detectable effect. In contrast, mutants from which the right-hand terC repeat, or both right- and left-hand repeats, had been deleted were unstable. None of the insertion or deletion mutations in or near repA4 affected plasmid copy number. Alteration of the terC repeats by site-directed mutagenesis had little effect on plasmid stability. Plasmid stability was not affected by a fus mutation known to inactivate the termination function. Therefore, it appears that the overall integrity of the repA4 region is more important for stable maintenance of plasmid NR1 than are any of the individual known features found in this region.

Exercise therapy of non-insulin dependent diabetes mellitus. Effects of acute exercise loading

The dynamic changes of 15 parameters (divided into 6 sections in this study) relating to metabolism, platelet function, blood coagulation and hemorrheologic situation under acute exercise loading with the intensity of VO2 max 60% were observed in noninsulin dependent diabetes mellitus (NIDDM) patients. The advantage, safety and feasibility of exercise therapy were discussed.

An in vitro model of cyclosporine-induced nephrotoxicity

The predominant hypothesis for cyclosporine-induced acute renal failure is postulated to be prerenal vasoconstriction with concomitant hemodynamic changes; an alternate hypothesis, however, may be that cyclosporine (CsA) affects intrarenal processes, i.e., direct renal parenchymal cell injury. However, reports on this direct effect of CsA on renal parenchymal cells are contradictory. Therefore, the purpose of this study was to address whether CsA is directly toxic to renal parenchymal cells in a primary culture system of rat renal cortical epithelial cells. The cytotoxicity of Sandimmune, the commercial form of CsA in a polyoxyethylated castor oil vehicle (Cremophor), CsA without vehicle, and the Cremophor vehicle was assessed by plasma membrane integrity (lactate dehydrogenase leakage), mitochondrial metabolic activity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction], and gross morphology (phase-contrast microscopy). The cytotoxicity of Sandimmune was also assessed by lysosomal activity (neutral red uptake), by proximal tubular enzyme activity (alkaline phosphatase), and by three fluorescent probes using a multiwell scanner. The three fluorescent probes were propidium iodide which stains nuclei of nonviable cells; bis-carboxyethyl-carboxyfluorescein which is retained by viable cells; and rhodamine 123, which assesses mitochondrial membrane potential. The results of this study demonstrated that Sandimmune caused dose- (10, 25, and 50 microM) and time- (12, 24, and 48 hr) dependent cytotoxicity, while Cremophor caused cytotoxicity only at high concentrations and long incubations. We conclude that (1) CsA is directly toxic to renal parenchymal cells in vitro and this system potentially represents a sensitive model for further mechanistic studies; (2) CsA plus vehicle (Sandimmune) was more cytotoxic to renal cells than CsA alone (without the polyoxyethylated castor oil vehicle).

Some properties of receptive fields of olfactory mitral/tufted cells in the frog

1. Different regions of the frog's olfactory epithelium were stimulated with nine glass micropipettes either individually or simultaneously in different combinations. The stimulus was a positive electrical pulse (4 s) consisting of a progressive increase, a plateau, and a progressive decrease in current intensity. Extra- and intracellular recordings were made from olfactory bulb mitral/tufted cells. Some of these cells were identified by intracellular injection of Lucifer yellow. 2. The action potential response patterns of mitral/tufted cells during the different phases of the stimulation were coded according to whether the activity was increased or decreased compared with its spontaneous level just before stimulation. Neural responses were classified into 11 types: individual neurons responded with different response types to stimuli delivered at different epithelial sites. On the basis of these response types, it was found that neurons could be classified into two groups. All response types in one group included an initial phase of increased discharge (excitation), whereas all types in the other group included an initial phase of decreased activity (suppression). Neurons that displayed response types belonging to one group never displayed those of the other group. It was thus concluded that a given neuron responded either always with an increased activity or always with a decreased activity, whatever the location of the stimulus. 3. The receptive field of a mitral/tufted cell appeared to be homogenous and not divided into areas of different properties, at least under the present experimental conditions. The extent of a receptive field was estimated by determining the number of effective epithelial sites (where an electrical stimulus evoked a response from a bulbar neuron).(ABSTRACT TRUNCATED AT 400 WORDS)

Morphological variations among output neurons of the olfactory bulb in the frog (Rana ridibunda)

Morphological properties of putative output cells have been studied in detail in the olfactory bulb of frogs (Rana ridibunda). Intracellular injection of Lucifer Yellow was used to reconstruct individual neurons. Ten different anatomical features related to cell shape and position were studied quantitatively. The results show that output cells, generally considered to be a homogeneous group in the olfactory bulb of amphibians, are, in fact, quite different in their morphology. Using multidimensional analysis to examine differences among the output neurons, we found that they might be divided into at least two groups. In one group, the cell somata were located near the glomerular layer and the dendrites lay at large angles with respect to each other. In the other group, the cell somata were farther from the glomerular layer and their dendrites lay at smaller angles. From their morphology, these two cell groups appear to be homologous, respectively, to the superficial/middle tufted cells and deep tufted/mitral cells of mammals.

Isolation and partial characterization of membrane-associated cyclophilin and a related 22-kDa glycoprotein

The presence of membrane-associated proteins which stereospecifically bind cyclosporin A and react with anti-cyclophilin antibodies has been documented in rat tissues. Extraction of membranes with 6 M urea or 0.5% Chaps releases cyclosporin-binding activity that is 5-12% of that found in cytosol. Cyclosporin-A-binding proteins are present in most subcellular organelles of liver, but microsomes contain the greatest activity. These proteins can be purified by adsorption onto a cyclosporin-A affinity column and elution with cyclosporin A. Two major fractions are resolved on SDS/PAGE: an 18-kDa fraction is comprised of two isoforms that are similar if not identical to the two major cytosolic isoforms of cyclophilin. In addition, in microsomes an approximately equal quantity of a 22-kDa glycoprotein was detected. Based on partial sequencing (five peptides, 89 amino acids) this protein is similar but not identical to human cyclophilin B. This 22-kDa isoform is poorly recognized by affinity-purified anti-cyclophilin antibodies and comprises several predominant isoforms (pI approximately 9.3-9.6). Selective binding of membrane 22-kDa cyclophilin to peanut lectin suggests the oligosaccharides contain a terminal galactosyl-N-galactosamine residue.

Production of a toxic, novel mammalian metabolite of N-methylcarbazole predicted by a fungal cell model of mammalian metabolism

The formation of N-hydroxymethylcarbazole (NHMC), carbazole, 1-hydroxy-N-methylcarbazole, 2-hydroxy-N-methylcarbazole, and 3-hydroxy-N-methylcarbazole as products of mammalian liver microsomal metabolism of N-methylcarbazole (NMC) has been documented by several investigators. In previous studies in our laboratory, the fungus Cunninghamella echinulata (ATCC 9244) produced two new metabolites, 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), and 3-hydroxycarbazole (3-OH-carbazole), in addition to the known mammalian metabolites, NHMC and carbazole. One of the two novel metabolites isolated from the microbial models, 3-OH-NHMC, was also identified and characterized in rat liver microsomes by analytical (HPLC) and spectral (UV and NMR) comparisons with a reference standard. The two metabolites, 3-OH-NHMC and 3-OH-carbazole, were shown to be cytotoxic to cultured rat hepatocytes as assessed by lactate dehydrogenase (LDH) leakage and neutral red (NR) uptake. These studies demonstrate the prospective potential of microbial models for predicting the formation of metabolites from drugs and other xenobiotics in mammalian systems.

[Relationship between the bacterial resistance induced by rifamdin and the RNA polymerase]

The results of our experiment in vitro showed that the activity of standard RNA polymerase decreased while the concentration of RFD and RFP increased, indicating that the target site of action of RFD was similar to that of RFP on RNA polymerase. Incorporation of [3H] UR into the RNA of sensitive cells of S. sureus and E. coli was strongly inhibited by RFD, but RFD did not affect the resistant strains. In purified DNA-dependent RNA polymerase of sensitive and resistant strains, the enzyme activity of sensitive E. coli a S. aureus strains was inhibited by RFD, but RFD did not inhibit that of the resistant strains (except the P. vulgaris). It can be concluded that a decreased susceptibility of RNA polymerase to RFD as well as a decreased permeability of bacterial envelope may induce bacterial resistance to the drug.

[Inhibitory effect of liuwei dihuang decoction on induced mutation and spontaneous tumor]

Anti-mutagenic activity was evaluated with micronuclear test. It appeared to be same between the result of mice treated with 10 g/kg Liuwei Dihuang decoction (LWDHd) for 3 days and that with 34.5 g/kg for 10 days. All the permillages of micronuclear appearance of treated groups were less than that of controls. The intercept (A) value of dose-effect curve were 12.7 and 9.4 as treated with cyclophosphamide (Cy) alone, but 1.2 and 3.2 as orally administered with LWDHd before injecting Cy. It showed that LWDHd could inhibite mutagenic activity of Cy. The affection of LWDHd on spontaneous tumorigenesis was observed in LACA mice. The tumor incidence rate was 9.0% in the control mice observed for 60 weeks, but 5.0% in the animal feeding LWDHd in food. The tumor incidence rate of big dose group was 1.0% and the difference was significant between it and that of the control (P less than 0.01).

Identification and boundary extraction of blobs in complex imagery

Automated identification and boundary extraction of blobs in "real world" imagery is a difficult task because the boundaries are so irregular that there is often insufficient a priori information describing these boundaries and traditional methods fail. This paper has proposed a progressive segmentation approach and a boundary estimation method to identify the blobs and to yield an accurate description of its boundary. The multiresolution image processing technique is incorporated into the whole work. This work has been applied to the problem of identifying and extracting the boundaries of major vessels (e.g., the aorta) in Magnetic Resonance (MR) imagery and the results are satisfactory. A Laplacian of Gaussian (LOG) operator is utilized as a spot detector to locate the approximate position of the blob of interest. A subimage centered on this approximate position is extracted to eliminate unwanted portions of the image and facilitate further processing. A histogram pyramid is created for the subimage histogram for automated determination of the threshold in the noisy histogram. A shrink-expand operation is then employed to reduced noise and undesired structures in the subimage. The rough and irregular boundary of the blob of interest obtained by thresholding is reparameterized into polar coordinates to create a Fourier descriptor representation of the boundary. Then, the discrete Fourier transform is applied to the reparameterized 1-D discrete curve to permit appropriate smoothing, as required, in frequency space. Finally, the boundary estimation is completed by taking the inverse Fourier transform to reconstruct the boundary of interest.