Opposing effects of ERK and JNK-p38 MAP kinases on apoptosis

Apoptosis plays an important role during neuronal development, and defects in apoptosis may underlie various neurodegenerative disorders. To characterize molecular mechanisms that regulate neuronal apoptosis, the contributions to cell death of mitogen-activated protein (MAP) kinase family members, including ERK (extracellular signal-regulated kinase), JNK (c-JUN NH2-terminal protein kinase), and p38, were examined after withdrawal of nerve growth factor (NGF) from rat PC-12 pheochromocytoma cells. NGF withdrawal led to sustained activation of the JNK and p38 enzymes and inhibition of ERKs. The effects of dominant-interfering or constitutively activated forms of various components of the JNK-p38 and ERK signaling pathways demonstrated that activation of JNK and p38 and concurrent inhibition of ERK are critical for induction of apoptosis in these cells. Therefore, the dynamic balance between growth factor-activated ERK and stress-activated JNK-p38 pathways may be important in determining whether a cell survives or undergoes apoptosis.

A cytoplasmic inhibitor of the JNK signal transduction pathway

The c-Jun amino-terminal kinase (JNK) is a member of the stress-activated group of mitogen-activated protein (MAP) kinases that are implicated in the control of cell growth. A murine cytoplasmic protein that binds specifically to JNK [the JNK interacting protein-1 (JIP-1)] was characterized and cloned. JIP-1 caused cytoplasmic retention of JNK and inhibition of JNK-regulated gene expression. In addition, JIP-1 suppressed the effects of the JNK signaling pathway on cellular proliferation, including transformation by the Bcr-Abl oncogene. This analysis identifies JIP-1 as a specific inhibitor of the JNK signal transduction pathway and establishes protein targeting as a mechanism that regulates signaling by stress-activated MAP kinases.

Neuroprotection by brain-derived neurotrophic factor is mediated by extracellular signal-regulated kinase and phosphatidylinositol 3-kinase

Apoptosis is a form of programmed cell death that plays a pivotal role during development and in the homeostasis of the adult nervous systems. However, mechanisms that regulate neuronal apoptosis are not well defined. Here, we report that brain-derived neurotrophic factor (BDNF) protects cortical neurons against apoptosis induced by camptothecin or serum deprivation and activates the extracellular-signal-regulated kinase (ERK) and the phosphatidylinositol 3-kinase (PI 3-kinase) pathways. Using pharmacological agents and transient transfection with dominant interfering or constitutive active components of the ERK or the PI 3-kinase pathway, we demonstrate that the ERK pathway plays a major role in BDNF neuroprotection against camptothecin. Furthermore, ERK is activated in cortical neurons during camptothecin-induced apoptosis, and inhibition of ERK increases apoptosis. In contrast, the PI 3-kinase pathway is the dominant survival mechanism for serum-dependent survival under normal culture conditions and for BDNF protection against serum withdrawal. These results suggest that the ERK pathway is one of several neuroprotective mechanisms that are activated by stress to counteract death signals in central nervous system neurons. Furthermore, the relative contribution of the ERK and PI 3-kinase pathways to neuronal survival may depend on the type of cellular injury.

A validated 1H NMR method for the determination of the degree of deacetylation of chitosan

A method for the determination of the degree of deacetylation (DDA) of chitosan by 1H NMR spectroscopy has been formally validated. Chitosans with DDA ranging from 48 to 100% have been used for the validation. The method is found to be simple, rapid and more precise than other known techniques like IR or titration for %DDA measurements. The precision, ruggedness, robustness, specificity, stability and accuracy of the technique are discussed in this paper.

Hysterectomy in the United States, 1988-1990

OBJECTIVE

To describe patient characteristics and diagnoses associated with hysterectomy in the United States from 1988-1990 using data from the National Hospital Discharge Survey.

METHODS

We analyzed data from the National Hospital Discharge Survey, an annual probability sample of discharges from nonfederal, short-stay hospitals in the United States. A population-based sample of all women aged 15 years or older in the United States civilian population who had a hysterectomy during 1988-1990 was examined to characterize factors associated with hysterectomy: patients' age and race, diagnoses, surgical approach, and oophorectomy.

RESULTS

Approximately 1.7 million women had a hysterectomy during 1988-1990. The highest rates--100.5 hysterectomies per 10,000 women--were for women aged 30-54 years. Total rates of hysterectomy for black women were similar to those for white women (61.7 and 56.5 per 10,000 women, respectively); uterine leiomyoma ("fibroid tumor") was reported as the primary diagnosis for 61% of black women and 29% of white women. Abdominal surgery was used for 75% of all hysterectomies. Concomitant bilateral oophorectomy was done for 37% of the women under 45 years old and 68% of the women 45 years or older.

CONCLUSIONS

Two-thirds of all hysterectomies for noncancerous conditions were performed for uterine leiomyoma or endometriosis--conditions that are most common before the age of menopause. Future assessments of the appropriateness of hysterectomy will require better understanding of these disorders. Continued monitoring of hysterectomy rates is critical to understanding the appropriate use of hysterectomy, alternative therapies for uterine disorders, and future trends in women's health care.

Reliable and global measurement of fluorescence resonance energy transfer using fluorescence microscopes

Green fluorescence protein (GFP)-based fluorescence resonance energy transfer (FRET) is increasingly used in investigation of inter- and intramolecular interactions in living cells. In this report, we present a modified method for FRET quantification in cultured cells using conventional fluorescence microscopy. To reliably measure FRET, three positive control constructs in which a cyan fluorescence protein and a yellow fluorescence protein were linked by peptides of 15, 24, or 37 amino acid residues were prepared. FRET was detected using a spectrofluorometer, a laser scanning confocal microscope, and an inverted fluorescence microscope. Three calculation methods for FRET quantification using fluorescence microscopes were compared. By normalization against expression levels of GFP fusion proteins, the modified method gave consistent FRET values that could be compared among different cells with varying protein expression levels. Whole-cell global analysis using this method allowed FRET measurement with high spatial resolutions. Using such a procedure, the interaction of synaptic proteins syntaxin and the synaptosomal associated protein of 25 kDa (SNAP-25) was examined in PC12 cells, which showed strong FRET on plasma membranes. These results demonstrate the effectiveness of the modified method for FRET measurement in live cell systems.

Nerve growth factor activates extracellular signal-regulated kinase and p38 mitogen-activated protein kinase pathways to stimulate CREB serine 133 phosphorylation

The mechanisms by which growth factor-induced signals are propagated to the nucleus, leading to the activation of the transcription factor CREB, have been characterized. Nerve growth factor (NGF) was found to activate multiple signaling pathways that mediate the phosphorylation of CREB at the critical regulatory site, serine 133 (Ser-133). NGF activates the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases (MAPKs), which in turn activate the pp90 ribosomal S6 kinase (RSK) family of Ser/Thr kinases, all three members of which were found to catalyze CREB Ser-133 phosphorylation in vitro and in vivo. In addition to the ERK/RSK pathway, we found that NGF activated the p38 MAPK and its downstream effector, MAPK-activated protein kinase 2 (MAPKAP kinase 2), resulting in phosphorylation of CREB at Ser-133. Inhibition of either the ERK/RSK or the p38/MAPKAP kinase 2 pathway only partially blocked NGF-induced CREB Ser-133 phosphorylation, suggesting that either pathway alone is sufficient for coupling the NGF signal to CREB activation. However, inhibition of both the ERK/RSK and the p38/MAPKAP kinase 2 pathways completely abolished NGF-induced CREB Ser-133 phosphorylation. These findings indicate that NGF activates two distinct MAPK pathways, both of which contribute to the phosphorylation of the transcription factor CREB and the activation of immediate-early genes.

Disruption of the type III adenylyl cyclase gene leads to peripheral and behavioral anosmia in transgenic mice

Cyclic nucleotide-gated ion channels in olfactory sensory neurons (OSNs) are hypothesized to play a critical role in olfaction. However, it has not been demonstrated that the cAMP signaling is required for olfactory-based behavioral responses, and the contributions of specific adenylyl cyclases to olfaction have not been defined. Here, we report the presence of adenylyl cyclases 2, 3, and 4 in olfactory cilia. To evaluate the role of AC3 in olfactory responses, we disrupted the gene for AC3 in mice. Interestingly, electroolfactogram (EOG) responses stimulated by either cAMP- or inositol 1,4,5-triphosphate- (IP3-) inducing odorants were completely ablated in AC3 mutants, despite the presence of AC2 and AC4 in olfactory cilia. Furthermore, AC3 mutants failed several olfaction-based behavioral tests, indicating that AC3 and cAMP signaling are critical for olfactory-dependent behavior.

The risk of pregnancy after tubal sterilization: findings from the U.S. Collaborative Review of Sterilization

OBJECTIVE

Our purpose was to determine the risk of pregnancy after tubal sterilization for common methods of tubal occlusion.

STUDY DESIGN

A multicenter, prospective cohort study was conducted in U.S. medical centers. A total of 10,685 women who underwent tubal sterilization was followed up for 8 to 14 years. The risk of pregnancy was assessed by cumulative life-table probabilities and proportional hazards models.

RESULTS

A total of 143 sterilization failures was identified. Cumulative 10-year probabilities of pregnancy were highest after clip sterilization (36.5/1000 procedures) and lowest after unipolar coagulation (7.5/1000) and postpartum partial salpingectomy (7.5/1000). The cumulative risk of pregnancy was highest among women sterilized at a young age with bipolar coagulation (54.3/1000) and clip application (52.1/1000).

CONCLUSIONS

Although tubal sterilization is highly effective, the risk of sterilization failure is higher than generally reported. The risk persists for years after the procedure and varies by method of tubal occlusion and age.

Altered behavior and long-term potentiation in type I adenylyl cyclase mutant mice

The murine Ca(2+)-stimulated adenylyl cyclase (type I) (EC 4.6.1.1), which is expressed predominantly in brain, was inactivated by targeted mutagenesis. Ca(2+)-stimulated adenylyl cyclase activity was reduced 40-60% in the hippocampus, neocortex, and cerebellum. Long-term potentiation in the CA1 region of the hippocampus from mutants was perturbed relative to controls. Both the initial slope and maximum extent of changes in synaptic response were reduced. Although mutant mice learned to find a hidden platform in the Morris water task normally, they did not display a preference for the region where the platform had been when it was removed. These results indicate that disruption of the gene for the type I adenylyl cyclase produces changes in behavior and that the cAMP signal transduction pathway may play an important role in synaptic plasticity.

Structures and mechanisms of Nudix hydrolases

Nudix hydrolases catalyze the hydrolysis of nucleoside diphosphates linked to other moieties, X, and contain the sequence motif or Nudix box, GX(5)EX(7)REUXEEXGU. The mechanisms of Nudix hydrolases are highly diverse in the position on the substrate at which nucleophilic substitution occurs, and in the number of required divalent cations. While most proceed by associative nucleophilic substitutions by water at specific internal phosphorus atoms of a diphosphate or polyphosphate chain, members of the GDP-mannose hydrolase sub-family catalyze dissociative nucleophilic substitutions, by water, at carbon. The site of substitution is likely determined by the positions of the general base and the entering water. The rate accelerations or catalytic powers of Nudix hydrolases range from 10(9)- to 10(12)-fold. The reactions are accelerated 10(3)-10(5)-fold by general base catalysis by a glutamate residue within, or beyond the Nudix box, or by a histidine beyond the Nudix box. Lewis acid catalysis, which contributes 10(3)-10(5)-fold to the rate acceleration, is provided by one, two, or three divalent cations. One divalent cation is coordinated by two or three conserved residues of the Nudix box, the initial glycine and one or two glutamate residues, together with a remote glutamate or glutamine ligand from beyond the Nudix box. Some Nudix enzymes require one (MutT) or two additional divalent cations (Ap(4)AP), to neutralize the charge of the polyphosphate chain, to help orient the attacking hydroxide or oxide nucleophile, and/or to facilitate the departure of the anionic leaving group. Additional catalysis (10-10(3)-fold) is provided by the cationic side chains of lysine and arginine residues and by H-bond donation by tyrosine residues, to orient the general base, or to promote the departure of the leaving group. The overall rate accelerations can be explained by both independent and cooperative effects of these catalytic components.

Tricyclic antidepressants inhibit IL-6, IL-1 beta and TNF-alpha release in human blood monocytes and IL-2 and interferon-gamma in T cells

Tricyclic antidepressants (TCAs) are widely used in treating depressive disorders. It has been demonstrated that, for instance, IL-1 beta and IL-6 inhibit the HPA axis, which plays a role in the development of depressions. Therefore. we were interested in investigating how TCAs influence cytokine release by T lymphocytes and monocytes respectively. Cells were incubated with either 5 microM clomipramine, 15 microM imipramine or 20 microM citalopram. IL-2 release was suppressed to 60% of the control values by clomipramine and imipramine (p = 0.001; p = 0.000), but citalopram was found to cause a much weaker inhibition (only 18%) (p = 0.16). INF-gamma release was affected to a lower degree than IL-2 release, and imipramine (34%) (p = 0.054) was more potent than clomipramine (24%) (p = 0.16) and citalopram (12%) (p = 0.059) in this case. Monocytes incubated with TCA for 4 h exhibited only limited inhibition of IL-1 beta and IL-6 release, i.e., 6-25% for all three compounds. The corresponding value for TNF-alpha release was 20-45% inhibition, with citalopram being the weakest inhibitor. After 10 h of monocytes to LPS exposure, all three compounds exerted a strong inhibition of IL-1 beta and TNF-alpha release, i.e., 60-70% with p-values below 0.012 for all of them. However the inhibition of IL-6 release was less than 35%. Citalopram was equality as potent as imipramine and clomipramine in inhibiting IL-6 release after long-term exposure of monocytes to LPS. All three TCAs elevated intracellular cAMP concentrations significantly in T lymphocytes and monocytes (p < 0.001).

Stimulation of the type III olfactory adenylyl cyclase by calcium and calmodulin

Characterization of adenylyl cyclases has been facilitated by the isolation of cDNA clones for distinct adenylyl cyclases including the type I and type III enzymes. Expression of type I adenylyl cyclase activity in animal cells has established that this enzyme is stimulated by calmodulin and Ca2+. Type III adenylyl cyclase is enriched in olfactory neurons and is regulated by stimulatory G proteins. The sensitivity of the type III adenylyl cyclase to Ca2+ and calmodulin has not been reported. In this study, type III adenylyl cyclase was expressed in human kidney 293 cells to determine if the enzyme is stimulated by Ca2+ and calmodulin. The type III enzyme was not stimulated by Ca2+ and calmodulin in the absence of other effectors. It was, however, stimulated by Ca2+ through calmodulin when the enzyme was concomitantly activated by either GppNHp or forskolin. The concentrations of free Ca2+ for half-maximal stimulation of type I and type III adenylyl cyclases were 0.05 and 5.0 microM Ca2+, respectively. These data suggest that the type III adenylyl cyclase is stimulated by Ca2+ when the enzyme is activated by G-protein-coupled receptors and that increases in free Ca2+ accompanying receptor activation may amplify the primary cyclic AMP signal.

Granzyme A loading induces rapid cytolysis and a novel form of DNA damage independently of caspase activation

Cytotoxic lymphocytes trigger apoptosis by releasing perforin and granzymes (Grn). GrnB activates the caspase apoptotic pathway, but little is known about GrnA-induced cell death. Perforin was used to load recombinant GrnA and GrnB and enzymatically inactive variants into target cells. GrnA induces single-strand DNA breaks that can be labeled with Klenow polymerase and visualized on alkaline gels. GrnA-induced DNA damage but not cytolysis requires GrnA proteolysis. GrnA-induced membrane perturbation, nuclear condensation, and DNA damage are unimpaired by caspase blockade. GrnA fails to induce cleavage of caspase-3, lamin B, rho-GTPase, or PARP. GrnA-induced cytotoxicity and cleavage of PHAP II, a previously identified GrnA substrate, are unimpaired in Jurkat cells that overexpress bcl-2. Therefore, GrnA activates a novel apoptotic pathway.

Type I calmodulin-sensitive adenylyl cyclase is neural specific

The distribution of type I calmodulin-sensitive adenylyl cyclase in bovine and rat tissues was examined by northern blot analysis and in situ hybridization. Northern blot analysis using poly(A)(+)-selected RNA from various bovine tissues indicated that mRNA for type I adenylyl cyclase was found only in brain, retina, and adrenal medulla, suggesting that this enzyme is neural specific. In situ hybridization studies using bovine, rabbit, and rat retina indicated that mRNA for type I adenylyl cyclase is found in all three nuclear layers of the neural retina and is particularly abundant in the inner segment of the photoreceptor cells. The neural-specific distribution of type I adenylyl cyclase mRNA and its restricted expression in areas of brain implicated in neuroplasticity are consistent with the proposal that this enzyme plays an important role in various neuronal functions including learning and memory.

The risk of ectopic pregnancy after tubal sterilization. U.S. Collaborative Review of Sterilization Working Group

BACKGROUND

Tubal sterilization is an increasingly common method of contraception in the United States. Although pregnancy after sterilization is uncommon, it can occur and may be ectopic. We used data from the U.S. Collaborative Review of Sterilization to estimate the risk of ectopic pregnancy in women who had undergone the common types of tubal sterilization.

METHODS

A total of 10,685 women undergoing tubal sterilization were followed in a multicenter, prospective cohort study. We intended to follow all the women for 5 years by means of annual telephone interviews; for women enrolled early in the study, we attempted an additional follow-up telephone interview 8 to 14 years after sterilization. To assess the risk of ectopic pregnancy in these women, we used cumulative life-table probabilities and proportional-hazards analysis.

RESULTS

There were 47 ectopic pregnancies in the 10,685 women; the 10-year cumulative probability of ectopic pregnancy for all methods of tubal sterilization combined was 7.3 per 1000 procedures. The cumulative probability varied substantially according to the method of sterilization and the woman's age at the time of sterilization. Women sterilized by bipolar tubal coagulation before the age of 30 years had a probability of ectopic pregnancy that was 27 times as high as that among women of similar age who underwent postpartum partial salpingectomy (31.9 vs. 1.2 ectopic pregnancies per 1000 procedures). The annual rate of ectopic pregnancy for all methods combined in the 4th through 10th years after sterilization was no lower than that in the first 3 years.

CONCLUSIONS

A history of tubal sterilization does not rule out the possibility of ectopic pregnancy, even many years after the procedure.

Blocking protein geranylgeranylation is essential for lovastatin-induced apoptosis of human acute myeloid leukemia cells

Lovastatin is an inhibitor of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the major regulatory enzyme of the mevalonate pathway. We have previously reported that lovastatin induces a significant apoptotic response in human acute myeloid leukemia (AML) cells. To identify the critical biochemical mechanism(s) essential for lovastatin-induced apoptosis, add-back experiments were conducted to determine which downstream product(s) of the mevalonate pathway could suppress this apoptotic response. Apoptosis induced by lovastatin was abrogated by mevalonate (MVA) and geranylgeranyl pyrophosphate (GGPP), and was partially inhibited by farnesyl pyrophosphate (FPP). Other products of the mevalonate pathway including cholesterol, squalene, lanosterol, desmosterol, dolichol, dolichol phosphate, ubiquinone, and isopentenyladenine did not affect lovastatin-induced apoptosis in AML cells. Our results suggest that inhibiting geranylgeranylation of target proteins is the predominant mechanism of lovastatin-induced apoptosis in AML cells. In support of this hypothesis, the geranylgeranyl transferase inhibitor (GGTI-298) mimicked the effect of lovastatin, whereas the farnesyl transferase inhibitor (FTI-277) was much less effective at triggering apoptosis in AML cells. Inhibition of geranylgeranylation was monitored and associated with the apoptotic response induced by lovastatin and GGTI-298 in the AML cells. We conclude that blockage of the mevalonate pathway, particularly inhibition of protein geranylgeranylation holds a critical role in the mechanism of lovastatin-induced apoptosis in AML cells.

Calmodulin-regulated adenylyl cyclases and neuromodulation

Coincidence detection and crosstalk between signal transduction systems play very important regulatory roles in the nervous system, particularly in the regulation of transcription. Coupling of the Ca2+ and cAMP regulatory systems by calmodulin-regulated adenylyl cyclases is hypothesized to be important for some forms of synaptic plasticity, neuroendocrine function, and olfactory detection. Recent studies of a mutant mouse deficient in type I calmodulin-sensitive adenylyl cyclase have provided the first evidence that adenylyl cyclases are important for synaptic plasticity, as well as for learning and memory in vertebrates.

Determination of the gene sequence and the three-dimensional structure at 2.4 angstroms resolution of methanol dehydrogenase from Methylophilus W3A1

The DNA sequences for the genes encoding the heavy and light subunits of methanol dehydrogenase from Methylophilus methylotrophus W3A1 have been determined. The deduced amino acid sequence has enabled the structure of the enzyme to be refined at 2.4 angstrom resolution against X-ray data collected on a Hamlin area detector. The structure was refined using the programs PROFFT and X-PLOR with several model building step interspersed. The final model contains two heavy chains (571 amino acids), two light chains (69 amino acids), two molecules of pyrroloquinoline quinone, two Ca2+ and 521 solvent molecules. Each half molecule contains four disulfide linkages and four cis peptides. One of the disulfides is formed from two adjacent cysteine residues linked by a trans peptide which creates a novel eight-membered ring. The heavy subunit is an 8-fold beta-propeller, each "blade" of which is a four-stranded antiparallel twisted beta-sheet. The light chain is an elongated subunit stretching across the surface of the heavy subunit, with residues 1 to 32 containing four beta-turns and residues 33 to 62 forming a helix; however, it neither interacts with the active site, nor the other HL dimer and its functional role is obscure. Around the 8-fold beta-propeller there is a repeating pattern of tryptophan residues located in the outer strand of seven of the eight beta-leaflets, each packed between adjacent leaflets. Each of these tryptophan residues is centered in the beta-strand and participates in the main chain hydrogen bonding of the sheet. Five of the seven tryptophan residues have closely similar interactions with the adjacent beta-leaflet including stacking of the tryptophan indole rings against a peptide plane and formation of a hydrogen bond from NE1 of the indole ring to a main-chain carbonyl. This repeating pattern is conserved over a number of MEDH sequences. The PQQ is located on the pseudo 8-fold rotation axis of the heavy subunit, in a funnel-shaped internal cavity, sandwiched between the indole ring of Trp237 and the two sulfur atoms of the Cys103-Cys104 vicinal disulfide. A hexacoordinate Ca2+ is bound in the active site by one nitrogen and five oxygen ligands, three from the PQQ and the others from two protein side-chains. In the active site an isolated solvent molecule is bound to the O5 of PQQ and to a nearby aspartate side-chain; its position may be the binding site for methanol. The aspartate might than serve as a general base for proton abstraction from the substrate hydroxyl. The C5 atom of PQQ could be activated by electrophilic catalysis by a nearby argenine side-chain or by the calcium ion bound to PQQ.

Construction and analysis of mouse strains lacking the ubiquitin ligase UBR1 (E3alpha) of the N-end rule pathway

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. In the yeast Saccharomyces cerevisiae, the UBR1-encoded ubiquitin ligase (E3) of the N-end rule pathway mediates the targeting of substrate proteins in part through binding to their destabilizing N-terminal residues. The functions of the yeast N-end rule pathway include fidelity of chromosome segregation and the regulation of peptide import. Our previous work described the cloning of cDNA and a gene encoding the 200-kDa mouse UBR1 (E3alpha). Here we show that mouse UBR1, in the presence of a cognate mouse ubiquitin-conjugating (E2) enzyme, can rescue the N-end rule pathway in ubr1Delta S. cerevisiae. We also constructed UBR1(-/-) mouse strains that lacked the UBR1 protein. UBR1(-/-) mice were viable and fertile but weighed significantly less than congenic +/+ mice. The decreased mass of UBR1(-/-) mice stemmed at least in part from smaller amounts of the skeletal muscle and adipose tissues. The skeletal muscle of UBR1(-/-) mice apparently lacked the N-end rule pathway and exhibited abnormal regulation of fatty acid synthase upon starvation. By contrast, and despite the absence of the UBR1 protein, UBR1(-/-) fibroblasts contained the N-end rule pathway. Thus, UBR1(-/-) mice are mosaics in regard to the activity of this pathway, owing to differential expression of proteins that can substitute for the ubiquitin ligase UBR1 (E3alpha). We consider these UBR1-like proteins and discuss the functions of the mammalian N-end rule pathway.

Arsenic induces apoptosis in rat cerebellar neurons via activation of JNK3 and p38 MAP kinases

Primary cultures of rat cerebellar neurons were used to study mechanisms of arsenic neurotoxicity. Exposure to 5, 10, or 15 microM sodium arsenite reduced cerebellar neuron viability and induced nuclear fragmentation and condensation as well as DNA degradation to oligonucleosome fragments. Exposure to 1 or 5 mM dimethylarsinic acid caused similar changes. Therefore, both inorganic arsenite and organic dimethylarsinic acid induce apoptosis in cerebellar neurons, with the inorganic form being more toxic. Cotreatment with cycloheximide or actinomycin D, inhibitors of protein or RNA synthesis, respectively, or with the caspase inhibitor zVAD, completely blocked arsenite-induced cerebellar neuron apoptosis. This implies that arsenite-induced cerebellar neuron apoptosis requires new gene expression and caspase activation. Interestingly, sodium arsenite selectively activated p38 and JNK3, but not JNK1 or JNK2 in cerebellar neurons. Blocking the p38 or JNK signaling pathways using the inhibitors SB203580 or CEP-1347 protected cerebellar neurons against arsenite-induced apoptosis. These data suggest that arsenite neurotoxicity may be due to apoptosis caused by activation of p38 and JNK3 MAP kinases.

Rate of hospitalization for gynecologic disorders among reproductive-age women in the United States

OBJECTIVE

To analyze reproductive-tract disorders that resulted in hospitalization of reproductive-age women in the United States.

METHODS

Data from the National Hospital Discharge Survey for 1988, 1989, and 1990 were used to study women 15-44 years old who had any gynecologic diagnoses noted in their discharge summaries.

RESULTS

Based on average annual discharge rates per 10,000 women, the five most frequent diagnostic groups were pelvic inflammatory disease (PID) (average annual rate 49.3, 95% confidence interval [CI] 43.6-55.0), benign cysts of the ovary (average annual rate 32.7, 95% CI 28.8-36.6), endometriosis (average annual rate 32.4, 95% CI 28.5-36.3), menstrual disorders (average annual rate 31.4, 95% CI 27.6-35.2), and uterine leiomyomas (average annual rate 30.4, 95% CI 26.7-34.1). The highest rates for PID were among women 25-39 years old and for women of races other than white. Highest rates for uterine leiomyomas were among women 40-44 years old and for women of races other than white. Highest rates for endometriosis were among women 40-44 years old and white women. Racial difference existed among all ages in the uterine leiomyoma and endometriosis groups. Average annual rates of benign cysts and menstrual disorders increased with age, but there were no statistically significant differences according to race in these two diagnostic groups.

CONCLUSIONS

Our findings confirmed the importance of PID as a common cause of hospitalization among reproductive-age women and identified additional gynecologic conditions as causes for hospitalization as well. We found significant age and racial differences not only among women with discharge diagnoses of PID but also among those with discharge diagnoses of uterine leiomyomas and endometriosis.