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A M Zimmerman

Publications and source records attributed to A M Zimmerman.

At least 19 recordsLinked to original sources
PubMed2001

The effects of hydrostatic pressure-induced changes on the cytoskeleton and on the regulation of gene expression in pheochromocytoma (PC-12) cells.

The purpose of this investigation was to determine the relationship of hydrostatic pressure-induced changes in the cytoarchitecture to regulation of gene expression in PC-12 cells. Hydrostatic pressure disrupts the cytoskeleton, decreases tubulin and actin mRNA levels and causes changes in the localization of tubulin and actin mRNA. Actin mRNA levels, at 6000 and 10,000 psi for 20 min, were reduced to 78% and 64%, respectively, in undifferentiated cells and to 81% and 72%, respectively, in 4-day differentiating cells, relative to untreated controls. Tubulin mRNA levels, at 6000 and 10,000 psi for 20 min, were reduced to 75% and 67%, respectively, in undifferentiated cells and to 84% and 74%, respectively, in 4-day differentiating cells. Changes in the localization of mRNA in the soluble and cytoskeletal fractions were determined by measuring the pressure level where the mRNA level in the cytoskeletal fraction equals the mRNA level in the soluble fraction. This measurement was designated the cytoskeletal/soluble fraction index (CSFI(50)). CSFI(50)measurements indicated that following hydrostatic pressure, actin mRNA cytoskeletal association was more stable than tubulin mRNA cytoskeletal association. The addition of chemicals which stabilize or destabilize microtubules and microfilaments to pressure treatment resulted in additional changes in the CSFI(50).

Actin Cytoskeleton↗
PubMed2001

Hydrostatic pressure induced changes in the cytoarchitecture of pheochromocytoma (PC-12) cells.

Confocal microscopy, in association with three-dimensional reconstruction, revealed that microtubules and microfilaments in differentiating PC-12 cells were disrupted in a dose-dependent manner following pressure treatment. Hydrostatic pressure caused cell rounding, microtubule and microfilament disorganization, neurite retraction and the formation of a microtubule ring adjacent to the cell surface. Volume analysis from computer-generated reconstructed cells, at atmospheric pressure, showed that the apparent volume of microtubules and microfilaments, normalized to 100 units, was 22 and 11 respectively. At 4000 and 8000 psi, the apparent microtubule volume was reduced to 16 and 12 units, respectively, and the apparent microfilament volume was reduced to 8 and 5 units, respectively. Thus, the apparent microtubule and microfilament volumes in PC-12 cells decreased as pressure increased. In the presence of taxol and phalloidin which stabilize the cytoarchitecture, cells resist the effects of hydrostatic pressure. In the presence of colchicine and cytochalasin D compounds which destabilize the cytoarchitecture, cells are more susceptible to the disrupting effects of hydrostatic pressure. The effects of hydrostatic pressure on cell morphology were reversible.

Actin Cytoskeleton↗
PubMed2000

Subcortical volumes in girls with tourette syndrome: support for a gender effect.

OBJECTIVE: To test whether girls with Tourette syndrome (TS) show subcortical morphology that differentiates them from control subjects. METHODS: MRI-based subcortical assessment was completed on 19 girls with TS age 7 to 15 years, 11 with TS only, and 8 with TS plus attention deficit hyperactivity disorder (TS + ADHD), and on 21 age- and sex-matched controls. The structures measured were the caudate, putamen, globus pallidus, and lateral ventricle volumes. Whole-brain-corrected volumes and asymmetry indices were compared using two- and three-group designs (i.e., TS versus control; TS-only versus TS + ADHD versus control). RESULTS: Two-group comparisons demonstrated no robust significant differences between girls with TS and gender-matched controls. Three-group comparisons demonstrated that TS-only subjects had significantly small lateral ventricles compared with TS + ADHD and control subjects. Because the two-group comparisons of the current study differed from previous reports of putamen asymmetry index as a marker for TS, retrospective comparisons with data from boys were performed. These additional comparisons showed that girls with TS had putamen asymmetry indices similar to those of boys with TS; however, control girls also showed those same patterns. CONCLUSIONS: Basal ganglia volume and asymmetry differences do not distinguish the girls with TS from matched controls. Gender differences confound the association between putamen asymmetry and TS. Although the numbers are small and the clinical significance is unclear, this study further indicates that girls with TS-only have smaller lateral ventricular volumes than control subjects and those with TS + ADHD.

Adolescent↗
PubMed2000

Infection: a stimulus for tic disorders.

The object of this study was to investigate the potential association of infections, especially group A hemolytic streptococcal infection, with the abrupt onset/exacerbation of tics or obsessive-compulsive behaviors. A structured clinical interview was used to evaluate 80 consecutive children, 5-17 years of age, with a diagnosis of tic disorder. Forty-two patients (53%) described a sudden, explosive onset or worsening of tic symptoms; 15 of these 42 had their exacerbation historically associated with an infection, nine of the 15 specifically with a streptococcal infection. Comparisons between those nine individuals and the remainder of the study population are presented. The results of this study reveal that descriptions of an abrupt tic onset or exacerbation are not uncommon in children with tic disorders; approximately 11% of children with tic disorders described abrupt changes of tic behavior within a 6-week period after a streptococcal infection.

Adolescent↗
PubMed2000

Formulation of a defined medium to maintain cell health and viability in vitro.

The first step in formulating a defined medium is to conduct a thorough search of the scientific literature. If a defined medium formulation is located that might be compatible with the intended cell system, a pilot study should be carried out to evaluate the general performance of the medium. Depending on the initial data obtained from this study, individual components of the medium and their concentrations may need to be manipulated (added/subtracted, increased/decreased) to obtain the desired results. Also, sometimes the basal medium or proportions of basal media must be changed. Because the formulation of a defined medium is a circular process, alteration of the basal medium type or ratio of basal media will necessitate redoing all of the previous addition/subtraction and optimization steps. Revalidation must also be done if vendors of components are changed or whenever different cells or cells of other ages are used in the system. This paper presents a brief procedure for formulating a defined media and an overview of the application of two defined media in muscle cell culture.

Animals↗
PubMed1996

Cannabinoid enantiomer action on the cytoarchitecture.

The negative and positive enantiomers of 7-hydroxy-delta 6-tetrahydrocannabinol-dimethylheptyl (designated HU-210 and HU-211 respectively) differentially affect undifferentiated and differentiating cultured pheochromocytoma cells (PC-12 cells). In general, cell viability and cell proliferation were suppressed to a much greater extent with HU-210 than with HU-211 in differentiating cells. The effects of these synthetic cannabinoids on the cytoskeleton of PC-12 cells were examined by epifluorescence and confocal microscopy. In both undifferentiated and differentiating PC-12 cells, HU-211 has little effect on the cytoarchitecture whereas HU-210 disrupts the distribution of microtubules and microfilaments. Vacuoles (2-4 microns) were evident in the cytoplasm of HU-210-treated cells but not in the cytoplasm of HU-211-treated cells or in vehicle controls. Tubulin and actin mRNA levels were reduced to 5 and 40%, respectively (relative to untreated controls) in 10 microns HU-210-treated cells whereas the same concentration of HU-211 reduced tubulin and actin mRNA levels to 90 and 95%, respectively. A comparison of the effects of the paired enantiomers and delta 1-THC on the cellular parameters studied reveals that in differentiating cells the action of delta 1-THC is intermediate between that of HU-210 and HU-211. This study demonstrates that compared to HU-210 and delta 1-THC the positive enantiomer HU-211 has little cellular activity.

Actin Cytoskeleton↗
PubMed1994

Anandamide (arachidonylethanolamide), a brain cannabinoid receptor agonist, reduces sperm fertilizing capacity in sea urchins by inhibiting the acrosome reaction.

Anandamide (arachidonylethanolamide) is an endogenous cannabinoid receptor agonist in mammalian brain. Sea urchin sperm contain a high-affinity cannabinoid receptor similar to the cannabinoid receptor in mammalian brain. (-)-delta 9-Tetrahydrocannabinol (THC), the primary psychoactive cannabinoid in marihuana, reduces the fertilizing capacity of sea urchin sperm by blocking the acrosome reaction that normally is stimulated by a specific ligand in the egg's jelly coat. We now report that anandamide produces effects similar to those previously obtained with THC in Strongylocentrotus purpuratus in reducing sperm fertilizing capacity and inhibiting the egg jelly-stimulated acrosome reaction. Arachidonic acid does not inhibit the acrosome reaction under similar conditions. The adverse effects of anandamide on sperm fertilizing capacity and the acrosome reaction are reversible. The receptivity of unfertilized eggs to sperm and sperm motility are not impaired by anandamide. Under conditions where anandamide completely blocks the egg jelly-stimulated acrosome reaction, it does not inhibit the acrosome reaction artificially initiated by ionomycin, which promotes Ca2+ influx, and nigericin, which activates K+ channels in sperm. These findings provide additional evidence that the cannabinoid receptor in sperm plays a role in blocking the acrosome reaction, indicate that anandamide or a related molecule may be the natural ligand for the cannabinoid receptor in sea urchin sperm, and suggest that binding of anandamide to the cannabinoid receptor modulates stimulus-secretion-coupling in sperm by affecting an event prior to ion channel opening.

Acrosome↗
PubMed1993

Environmental magnetic fields: influences on early embryogenesis.

A 10-mG, 50 to 60-Hz magnetic field is in the intensity and frequency range that people worldwide are often exposed to in homes and in the workplace. Studies about the effects of 50- to 100-Hz electromagnetic fields on various species of animal embryos (fish, chick, fly, sea urchin, rat, and mouse) indicate that early stages of embryonic development are responsive to fluctuating magnetic fields. Chick, sea urchin, and mouse embryos are responsive to magnetic field intensities of 10-100 mG. Results from studies on sea urchin embryos indicate that exposure to conditions of rotating 60-Hz magnetic fields, e.g., similar to those in our environment, interferes with cell proliferation at the morula stage in a manner dependent on field intensity. The cleavage stages, prior to the 64-cell stage, were not delayed by this rotating 60-Hz magnetic field suggesting that the ionic surges, DNA replication, and translational events essential for early cleavage stages were not significantly altered. Studies of histone synthesis in early sea urchin embryos indicated that the rotating 60-Hz magnetic field decreased zygotic expression of "early" histone genes at the morula stage and suggests that this decrease in early histone production was limiting to cell proliferation. Whether these comparative observations from animal development studies will be paralleled by results from studies of human embryogenesis, as suggested by some epidemiology studies, has yet to be established.

Animals↗
PubMed1993

Evidence for a cannabinoid receptor in sea urchin sperm and its role in blockade of the acrosome reaction.

Delta-9-tetrahydrocannabinol ((-)delta 9 THC), the primary psychoactive cannabinoid in marihuana, reduces the fertilizing capacity of sea urchin sperm by blocking the acrosome reaction that normally is stimulated by a specific ligand in the egg's jelly coat. The bicyclic synthetic cannabinoid [3H]CP-55,940 has been used as a ligand to demonstrate the presence of a cannabinoid receptor in mammalian brain. We now report that [3H]CP-55,940 binds to live sea urchin (Strongylocentrotus purpuratus) sperm in a concentration, sperm density, and time-dependent manner. Specific binding of [3H]CP-55,940 to sperm, defined as total binding displaced by (-)delta 9THC, was saturable: KD 5.16 +/- 1.02 nM; Hill coefficient 0.98 +/- 0.004. This suggests a single class of receptor sites and the absence of significant cooperative interactions. Sea urchin sperm contain 712 +/- 122 cannabinoid receptors per cell. Binding of [3H]CP-55,940 to sperm was reduced in a dose-dependent manner by increasing concentrations of CP-55,940, (-)delta 9THC, and (+)delta 9THC. The rank order of potency to inhibit binding of [3H]CP-55,940 to sperm and to block the egg jelly stimulated acrosome reaction was: CP-55,940 > (-)delta 9THC > (+)delta 9THC. These findings show that sea urchin sperm contain a stereospecific cannabinoid receptor that may play a role in inhibition of the acrosome reaction. The radioligand binding data obtained with live sea urchin sperm are remarkably similar to those previously published by other investigators using [3H]CP-55,940 on mammalian brain and nonneural tissues. The cannabinoid binding properties of this receptor appear to have been highly conserved during evolution. We postulate that the cannabinoid receptor may modulate cellular responses to stimulation.

Acrosome↗
PubMed1991

Reduction of the fertilizing capacity of sea urchin sperm by cannabinoids derived from marihuana. I. Inhibition of the acrosome reaction induced by egg jelly.

delta 9-Tetrahydrocannabinol (THC) and two other major cannabinoids derived from marihuana--cannabidiol (CBD) and cannabinol (CBN)--inhibit fertilization in the sea urchin Strongylocentrotus purpuratus by reducing the fertilizing capacity of sperm (Schuel et al., 1987). Sperm fertility depends on their motility and on their ability to undergo the acrosome reaction upon encountering the egg's jelly coat. Pretreatment of S. purpuratus sperm with THC prevents triggering of the acrosome reaction by solubilized egg jelly in a dose (0.1-100 microM) and time (0-5 min)-dependent manner. Induction of the acrosome reaction is inhibited in 88.9 +/- 2.3% of sperm pretreated with 100 microM THC for 5 min, while motility of THC-treated sperm is not reduced compared to solvent (vehicle) and seawater-treated controls. The acrosome reaction is inhibited 50% by pretreatment with 6.6 microM THC for 5 min and with 100 microM THC after 20.8 sec. CBN and CBD at comparable concentrations inhibit the acrosome reaction by egg jelly in a manner similar to THC. THC does not inhibit the acrosome reaction artificially induced by ionomycin, which promotes Ca2+ influx, and nigericin, which promotes K+ efflux. THC partially inhibits (20-30%) the acrosome reaction induced by A23187, which promotes Ca2+ influx, and NH4OH, which raises the internal pH of the sperm. Addition of monensin, which promotes Na+ influx to egg jelly or to A23187, does not overcome the THC inhibition. Inhibition of the egg jelly-induced acrosome reaction by THC produces a corresponding reduction in the fertilizing capacity of the sperm. The adverse effects of THC on the acrosome reaction and sperm fertility are reversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1991

Cannabinoids inhibit fertilization in sea urchins by reducing the fertilizing capacity of sperm.

Delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) inhibit fertilization in the sea urchin Strongylocentrotus purpuratus by reducing the fertilizing capacity of the sperm. Sperm fertility depends upon their motility, and their capacity to undergo the acrosome reaction upon encountering a specific ligand derived from the egg's jelly coat. The acrosome reaction involves exocytosis of the acrosomal granule at the apex of the sperm head and elongation of the acrosomal filament. This process exposes the sperm membrane that will attach to and fuse with the egg. Pretreatment of sperm with THC prevents the triggering of the acrosome reaction by solubilized egg jelly in a dose and time dependent manner. Motility of THC-treated sperm is not reduced compared to control sperm in sea water or vehicle dissolved in sea water. The adverse effects of THC on the acrosome reaction and sperm-fertilizing capacity are reversible. Studies with ionophores suggest that THC blocks the acrosome reaction by affecting event(s) in the stimulation-secretion coupling mechanism in the sperm preceding the opening of ion channels. Ultrastructural studies show that THC, CBD and CBN block the membrane fusion reaction between the sperm's plasma membrane and the acrosomal membrane that normally is elicited in response to stimulation by egg jelly to initiate the acrosome reaction. However, lipid deposits are found in the subacrosomal and centriolar fossae of cannabinoid treated sperm. The nuclear envelope is fragmented in close proximity to the lipid deposits within the subacrosomal fossa. These morphological observations suggest that cannabinoids may activate phospholipase(s) within the sperm. Biochemical studies show that THC activates phospholipase A2 activity in sperm homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1991

Influence of marihuana on cellular structures and biochemical activities.

Cannabinoids are known to affect a number of cellular systems and functions, but the basis for their action is unclear. In this paper we review the current evidence describing cannabinoid effects on various levels of cellular structure and activity and we present our current studies on the influence of delta-9-tetrahydrocannabinol, cannabidiol and cannabinol on one cellular system, the cytoskeleton. The organization of two cytoskeletal structures, microtubules and microfilaments, were examined and the mRNA levels of tubulin and actin, the major protein components of microtubules and microfilaments, respectively, were analysed.

Animals↗
PubMed1991

Hydrostatic pressure influences histone mRNA.

Exposure of HeLa S3 cells to high hydrostatic pressure (6.89 x 10(3) to 6.89 x 10(4) kPa: 1000 to 10,000 lbfin-2) reduced core and H1 histone mRNA levels as determined by hybridization to specific histone DNA probes. At 4.14 x 10(4) kPa for 10 min core histone and H1 histone mRNA levels were reduced 32-38% and 56%, respectively. At 30 min postdecompression core mRNA levels returned to atmospheric control levels while H1 histone mRNA levels continued to be suppressed. Levels of macromolecular synthesis were monitored under hydrostatic pressure with radioactive precursors of RNA, DNA and protein. Macromolecular synthesis was shown to be suppressed in a dose-dependent manner with increasing magnitude and duration of pressure. To determine the influence of pressure on histone mRNA stability, actinomycin D (10 micrograms ml-1) was used to block RNA synthesis. Relative amounts of H4 and H1 mRNA were determined at atmospheric pressure and following treatment with actinomycin D (10 micrograms ml-1), pressure (4.14 x 10(4) kPa) and a combination of pressure and actinomycin D. This study shows that a synthesis component and a stability component are involved in the pressure-induced reduction of core histone mRNA. At 4.14 x 10(4) kPa for 15 min, there was a 42% reduction in core histone mRNA of which approximately one third was due a suppression of transcription and two thirds to a loss of mRNA stability. The pressure-induced reduction in histone mRNA is attributed to the instability of endogenous histone mRNA and a reduction in transcription/processing of new histone mRNA.

HeLa Cells↗
PubMed1990

Influence of 60-Hz magnetic fields on sea urchin development.

Continuous exposure of sea urchin (Strongylocentrotus purpuratus) embryos at 18 degrees C to a cyclic 60-Hz magnetic field at 0.1 mT rms beginning 4 min after insemination caused a significant developmental delay during the subsequent 23 hours. No delay in development was recorded for periods up to 18 hours after fertilization. At 18 h, most embryos were in the mesenchyme blastula stage. At 23 h, most control embryos were in mid-gastrula whereas most magnetic-field-exposed embryos were in the early gastrula stage. Thus an estimated 1-h delay occurred between these developmental stages. The results are discussed in terms of possible magnetic-field modification of transcription as well as interference with cell migration during gastrulation. The present study extends and supports the growing body of information about potential effects of exposures to extremely-low-frequency (ELF) magnetic fields on developing organisms.

Animals↗
PubMed1990

The effects of delta-9-tetrahydrocannabinol on actin microfilaments.

Fluorescence staining with rhodamine phalloidin specific for F-actin was employed to examine the effects of delta-9-tetrahydrocannabinol (THC) on the distribution of microfilaments in kangaroo rat epithelial cells (PtK2) and rabbit aortic endothelial cells (RAE). PtK2 cells were more sensitive to THC treatment than RAE cells. Exposure of PtK2 cells to 10 microM THC for 2 h disrupted the microfilament network. After treatment with 20 microM THC for 2 h there was a loss of cell-to-cell contact between PtK2 cells, and at 30 microM THC, the cells started to detach from the substratum. In contrast, microfilament disorganization but not cell detachment was observed in RAE cells at THC concentrations of 80 and 100 microM. The possible mechanisms which may account for the changes in the microfilament system are discussed.

Actin Cytoskeleton↗
PubMed1989

Stereospecific effects of (-)- and (+)-7-hydroxy-delta-6-tetrahydrocannabinol-dimethylheptyl on the immune system of mice.

The effects of the (+) and (-) cannabinoid enantiomers 7-hydroxy-delta-6-tetra-hydrocannabinol-dimethylheptyl [(-)-7-OH-delta-6-THC-DMH (HU-210) and (+)-7-OH-delta-6-THC-DMH (HU-211)] on the inductive and productive phases of the primary humoral immune response to sheep red blood cell immunization were investigated in mice. Animals treated with (-)-7-OH-delta-6-THC-DMH (0.01, 0.05, 0.1 and 0.5 mg/kg) exhibited a dose-dependent suppression of both phases of the primary humoral immune response in the hemolytic plaque assay, the hemagglutination titer and in the ratio of the spleen weight to final body weight. Mice treated with (+)-7-OH-delta-6-THC-DMH (0.01, 0.05, 0.01, 0.5 and 1.0 mg/kg) did not exhibit dose-dependent immune suppression. However, the (+) enantiomer reduced the number of plaque-forming cells in the hemolytic plaque assay during the inductive phase. Mice treated with a combination of (-) and (+) enantiomers, each at 0.01 mg/kg, exhibited no impairment in ability to undergo a primary humoral immune response (inductive phase).

Animals↗
PubMed1988

Pressure sensitivity of tubulin expression in Tetrahymena.

A reduction in tubulin mRNA levels up to 35-40 min following pressure (10,000 psi for 5 min) was shown by cDNA hybridization in log growth phase and deciliated Tetrahymena. The level of tubulin mRNA increased to a maximum 1 hour after pressure release. Poly(A+) mRNA derived from pressure-treated and atmospheric control cells following deciliation was translated in vitro. The profile for tubulin synthesized in vitro closely resembled the tubulin mRNA profiles. In vivo tubulin synthesis measured by 35S methionine incorporation was suppressed 60%, 40 min following pressure release. The data supports the hypothesis that both transcription and post transcriptional events are sensitive to hydrostatic pressure.

Animals↗