Sleep characteristics before assisted reproductive technology treatment predict reproductive outcomes: a prospective cohort study of Chinese infertile women

Sleep disorders affect mental and physical health. Infertile women undergoing assisted reproductive technology (ART) treatment are prone to sleep disorders. Sleep condition, its influencing factors, and the association between sleep condition and ART treatment outcomes before treatment have not been explored within a population with a large sample size. Therefore, we investigated the sleep characteristics of 1002 Chinese infertile women before ovulation induction and investigated the influencing factors (negative and positive psychological factors, demographics, and fertility characteristics). We also examined whether sleep conditions before treatment predicted reproductive outcomes. We found that 24.1% of participants reported poor sleep quality. Women with primary infertility reported poorer sleep than women with secondary infertility. Negative psychological factors, including depression, anxiety, and perceived stress were associated with poor sleep, whereas positive affect was linked with good sleep. Adverse sleep characteristics, including poor subjective sleep quality, sleep disturbances, and poor sleep efficiency, decreased the quantity and quality of oocytes retrieved, fertilization rates, and clinical pregnancy rates. This study indicates that before ART treatment, a large number of females with infertility suffer from sleep problems, which are affected by psychological factors and infertility type, and unhealthy sleep characteristics may impair treatment outcomes. Our findings highlight the importance of screening and treatment for sleep disorders before the enrollment of ART treatment in infertile women.

Extracellular vesicles, hyperadhesive von willebrand factor, and outcomes of gastric cancer: a clinical observational study

Von Willebrand factor (VWF) is an adhesive ligand critical for maintaining hemostasis. However, it has also been increasingly recognized for its role in cancer development because it has been shown to mediate the adhesion of cancer cells to endothelial cells, promote the epithelial-mesenchymal transition, and enhance angiogenesis. We have previously shown that gastric cancer cells synthesize VWF, which mediates the interaction between the cancer and endothelial cells to promote cancer growth. Here, we report results from a clinical observational study that demonstrate the association of VWF in plasma and on the surface of extracellular vesicles (EVs) with the pathological characteristics of gastric cancer. We found that patients with gastric cancer had elevated and intrinsically hyperadhesive VWF in their peripheral blood samples. VWF was detected on the surface of EVs from cancer cells, platelets, and endothelial cells. Higher levels of these VWF-bound EVs were associated with cancer aggression and poor clinical outcomes for patients. These findings suggest that VWF⁺ EVs from different cell types serve collectively as a new class of biomarkers for the outcome assessment of gastric cancer patients.

Gastric cancer cell-derived extracellular vesicles disrupt endothelial integrity and promote metastasis

The endothelium is the critical barrier that controls transendothelial communications. Blood vessels in cancer tissue are poorly developed and highly permeable. However, it is poorly understood how circulating cancer cells released through these "leaky" vessels break the intact vasculature of remote organs to metastasize. We investigated the roles of cancer cell-derived extracellular vesicles (CEVs) in regulating cancer metastasis by analyzing samples from gastric cancer patients, performing in vitro experiments, and studying mouse models. We made several novel observations. First, the rate of metastasis was closely associated with plasma levels of CEVs in patients with gastric cancer. Second, cultured endothelial cells endocytosed CEVs, resulting in cytoskeletal rearrangement, low expression of the junction proteins cadherin and CD31, and forming large intercellular gaps to allow the transendothelial migration of cancer cells. The dynamin inhibitor Dynasore prevented these CEV-induced changes of endothelial cells by blocking CEVs endocytosis. Third, CEVs disrupted the endothelial barrier of cancer-bearing mice to promote cancer metastasis. Finally, lactadherin promoted the clearance of circulating CEVs to reduce metastasis. These results demonstrate the essential role of CEVs in promoting the metastasis of gastric cancer.

A Modiied 3-Way Tap to Enhance the Stability and Uniformity of Sclerosant Foam

BACKGROUND

The Tessari method, mixing air with the sclerosant through a 3-way tap and 2 syringes, is the most widely used method to prepare foam in foam sclerotherapy. Uniform foam with smaller bubbles has great clinical significance for venous insufficiency. We aim to modify the traditional 3-way tap to produce more uniform and stable foam with smaller bubbles.

METHODS

The traditional 3-way tap was modified by inserting a porous film within its channel.

EXPERIMENT DESIGN

the foam was prepared with 2 mL polidocanol plus 8 mL air plus 0.05 mL hyaluronic acid; group 1, foam prepared with 20 quick passes through a traditional 3-way tap; and groups 2-7, foam prepared using the modified 3-way tap, with 10, 12, 14, 16, 18, and 20 quick passes, respectively. The uniformity of the foam was observed under optical microscopy, and the size of bubbles quantified using the Nano measurement software. The stability of the foam was evaluated using the foam half-life time.

RESULTS

The foam half-life times of groups 1-7 were 306.4, 257.4, 285.6, 304.4, 318.6, 330.2, 331.3 sec, respectively. The modified tap also produced a more uniform distribution of smaller bubbles (group 7) compared with traditional tap (group 1).

CONCLUSIONS

Modified 3-way tap enhanced the stability of the sclerosant foam, with a more uniform distribution of smaller bubbles.

Cancer cell-derived von Willebrand factor enhanced metastasis of gastric adenocarcinoma

Cancer prognosis is poor for patients with blood-borne metastasis. Platelets are known to assist cancer cells in transmigrating through the endothelium, but ligands for the platelet-mediated cancer metastasis remain poorly defined. von Willebrand factor (vWF) is a major platelet ligand that has been widely used as a biomarker in cancer and associated inflammation. However, its functional role in cancer growth and metastasis is largely unknown. Here we report that gastric cancer cells from patients and cells from two well-established gastric cancer lines express vWF and secrete it into the circulation, upon which it rapidly becomes cell-bound to mediate cancer-cell aggregation and interaction with platelets and endothelial cells. The vWF-mediated homotypic and heterotypic cell-cell interactions promote the pulmonary graft of vWF-overexpressing gastric cancer BGC823 cells in a mouse model. The metastasis-promoting activity of vWF was blocked by antibodies against vWF and its platelet receptor GP Ibα. It was also reduced by an inhibitory siRNA that suppresses vWF expression. These findings demonstrate a causal role of cancer-cell-derived vWF in mediating gastric cancer metastasis and identify vWF as a new therapeutic target.

Effect of Qingfei Mixture () on pediatric mycoplasma pneumoniae pneumonia with phlegm heat obstructing Fei (Lung) syndrome

OBJECTIVE

To explore the effect and mechanism of Qingfei Mixture (), a Chinese medicine, in treating mycoplasma pneumonia (MP) in MP patients and rat model METHODS: A total of 46 MP children with phlegm heat obstructing Fei (Lung) syndrome were randomly assigned to two groups by the method of random number table, with 23 children in each group. The control group was treated with intravenous infusion of azithromycin; the treatment group received intravenous infusion of azithromycin and oral administration of Qingfei Mixture. The treatment course was 7 days. Major symptoms and minor symptoms were observed and scored before and after treatments. A rat model of MP was also established. A total of 120 wistar rats were randomly divided into 5 groups: a normal group, infection group, Qingfei Mixture treatment group, azithromycin treatment group, and Qingfei Mixture + azithromycin treatment group. Each group contained 24 rats, from which every 6 were euthanatized 1, 3, 7 and 14 days after infection. MP DNA in pulmonary tissue homogenates was detected using real-time fluorescence quantitative polymerase chain reaction. Pathology was assessed after hematoxylin (HE) staining and lung tissue pathology scores were determined in pulmonary tissue. Transmission electron microscopic detection and electronic image analysis were performed on lung tissue 3 days after infection. Interleukin (IL)-17 was detected in serum using enzymelinked immunosorbent assay (ELISA) 7 days after infection.

RESULTS

In the clinical study, both control and the treatment group showed improved results on removing symptoms of phlegm heat syndrome compared to the control group (P<0.05). In animal experiments, On the 7th day after MP infection, as detected by electron microscopy, the pulmonary capillary basement membranes of the azithromycin + Qingfei Mixture treatment group were much thinner than those of the azithromycin or Qingfei mixture treatment groups (P<0.05). The level of serum IL-17 in the azithromycin + Qingfei Mixture treatment group was lower than that in the azithromycin or Qingfei Mixture groups (P<0.01).

CONCLUSION

Both Qingfei Mixture and azithromycin have therapeutic effects on mycoplasma pneumoniae pneumonia, but the combination of both agents had the greatest effect.

Pulse oximetry screening for critical congenital heart disease in planned out of hospital births and the incidence of critical congenital heart disease in the Plain community

OBJECTIVE

This study evaluated pulse oximetry screening (POS) for critical congenital heart disease (CCHD) in planned out of hospital births with special attention to births in Plain communities (Amish, Mennonite and similar).

STUDY DESIGN

Wisconsin out of hospital births in 2013 and 2014 were evaluated. Care providers were supplied with and trained in the use of pulse oximeters for CCHD screening. State records were reviewed to identify deaths and hospital admissions due to CCHD in this population.

RESULTS

Detailed information on POS was available in 1616 planned out of hospital births. Seven hundred and ninety-nine were from the Plain community. In total, 1584 babies (98%) passed their POS, 16 infants (1%) failed and 16 (1%) were not screened. Five infants from the Plain community had CCHD and three were detected by POS.

CONCLUSION

POS for CCHD can be successfully implemented outside the hospital setting and plays a particularly important role in communities with high rates of CCHD and where formal prenatal screening is uncommon.

[Three-dimensional cell culture and histology of vasculogenic mimicry in hepatocellular carcinoma]

BACKGROUND & OBJECTIVE

Vasculogenic mimicry (VM) is a blood supply pattern in malignant tumors. Mimic vessel walls are formed by tumor cells, not by endothelial cells. Previous studies of VM are limited on malignant tumors with high aggression and bi-directional differentiation potentials, but seldom on epithelium-originated tumors. This study was to observe VM in hepatocellular carcinoma (HCC) by 3-dimensional culture of HCC cell line HepG2 and immunohistochemistry.

METHODS

Three-dimensional culture system of HepG2 cells was constructed to observe VM. The presence of VM in 15 specimens of HCC was observed by immunohistochemical and histological double staining of CD31 and PAS, or Ferritin and PAS.

RESULTS

During 3-dimensional culture, HepG2 cells stretched out thin and long apophyses at the second day, and linked each other to form wreath and net-work structure at the seventh day. All of the 15 HCC simples showed CD31-positive for endothelial cells, and Ferritin-positive for tumor cells. The immunohistochemical and histological double staining also proved that VM, formed by CD31-negative and Ferritin-positive tumor cells, existed in 7 of the 15 simples of HCC. Tumor cells were separated from the tubes by PAS-positive matter like basement membrane. Red blood cells could be seen in the tubes. The number of VM was less in well differentiated simples than in poorly differentiated samples; CD31-positive tumor cells were observed in poorly differentiated samples.

CONCLUSIONS

HepG2 cells have the capacity of self-metamorphosing and vasculorizing. Tumor cells can obtain oxygen and nutrition through VM.

[Multicentral randomized controlled studies on acupuncture at Shaoze (SI 1) for treatment of postpartum hypolactation]

OBJECTIVE

To explore effect of acupuncture at Shaoze (SI 1) for treatment of postpartum hypolactation.

METHODS

Multicentral randomized controlled and single blind clinical trial was adopted, and 276 cases were divided into a treatment group and a control group, 138 cases in each group. The treatment group were treated with electroacupuncture (EA) at Shaoze (SI 1) and the control group with EA at Shangyang (LI 1). After treatment of 2 courses, the therapeutic effects and changes of cumulative score of TCM symptoms, mammary filling degree, lactation amount, prolactin level were evaluated and investigated.

RESULTS

The cured and markedly effective rate was 97.8% in the treatment group and 24.3% in the control group with a significant difference between the two groups (P < 0.05). The treatment group in improvement of the cumulative score of TCM symptoms and the mammary filling degree, and increasing the lactation amount and the prolactin level were better than the control group (P < 0.01).

CONCLUSION

Acupuncture at Shaoze (SI 1) has obvious therapeutic effect on hypolactation.

[Effects on development of the testicle in diet-induced obesity rats]

OBJECTIVE

We established diet-induced obesity animal model and observed the influence of obesity on testicle of the male rats.

METHODS

Rats in model group were fed with fat-enriched diet for 6 weeks. We measured the body weight and the testis weight and observed the development of testicle by microscope, and compared with those of control group. Meanwhile, we measured the serum levels of testosterone (T) and estradiol (E2).

RESULTS

The average body weight in model group rats was higher 29% than that in control group at 6 weeks old, 30% at 9 weeks old. We observed under microscope that most of the convoluted seminiferous tubule developed no good in model group, the 4 layer cells was sparse and the arrangement of them was not in order. The testosterone to estradiol ratios(T/E2) in model group was significant lower then that of control group (P < 0.05).

CONCLUSION

The fat-enriched fat diet can induce obesity. It influenced the development of the testicle. This probably related to decrease of the testosterone to estradiol ratios.

Opposite effects of lithium on proximal and distal caspases of immature and mature primary neurons correlate with earlier paradoxical actions on viability

To provide an explanation for earlier paradoxical findings of lithium on survival of mature and immature neurons, this study monitors changes in cytosolic caspases in rat cerebellar granule cells (CGC) grown 2-7 days in vitro (DIV), or in murine E-17 cortical neurons. Data show Li+ protects mature 7-DIV CGC parallel to a decrease in proximal and distal caspases but increases levels for immature 2-DIV-CGC or E-17 cortical neurons. Caspases mirror viability based on morphological analyses (dye uptake, phase-contrast, DNA fragmentation), and suggest protection occurs by suppressing activation of a cascade resulting in distal effectors that destroy proteins essential for neuronal survival. Protection was dose-dependent with EC50 3.0 mM and extended to 64 h in K+-serum deprived apoptotic media. Neuronal extracts contain a spectrum of proximal (-2, -8, -9) and distal (-3, -6) caspases sensitive to Li+ on assay with preferred peptide substrates and by immunoblotting. The lack of direct effect on activated cytosols indicates Li+ acts upstream only on intact cells, at sites for recruitment of pivotal procaspases. Alterations of procaspase-9 p46 and membrane-bound cytochrome c (Apaf-1) point to interaction with an intrinsic Mt-mediated pathway as one of the targets. The opposite effects on caspases and viability of immature or embryological neurons point to existence of alternative pathways that alter during neurite outgrowth suggesting the use of Li+ as a probe to unravel events relevant to neurogenesis.

Lysosomal membrane damage in soluble Abeta-mediated cell death in Alzheimer's disease

Our previous studies suggest that a failure to degrade aggregated Abeta1-42 in late endosomes or secondary lysosomes is a mechanism that contributes to intracellular accumulation in Alzheimer's disease. In this study, we demonstrate that cultured primary neurons are able to internalize soluble Abeta1-42 from the culture medium and accumulate inside the endosomal/lysosomal system. The intracellular Abeta1-42 is resistant to protease degradation and stable for at least 48 h within the cultured neurons. Incubation of cultured neurons with a cytotoxic concentration of soluble Abeta1-42 invokes the rapid free radical generation within lysosomes and disruption of lysosomal membrane proton gradient which precedes cell death. The loss of lysosomal membrane impermeability is only specific to the Abeta1-42 isoform since incubation of cells with high concentrations of Abeta1-40 has no effect on lysosomal hydrolase release. To further support the role of lysosomal membrane damage in Abeta-mediated cell death, we demonstrate that photodisruption of acridine orange (AO)-loaded lysosomes with intense blue light induces a relatively rapid synchronous lysosomal membrane damage and neuronal death similar to that observed as a result of Abeta exposure. AO leaks quickly from late endosomes and lysosomes and partially shifts the fluorescence from an orange fluorescence to a diffuse, green cytoplasmic fluorescence. Such AO relocalization is due to an initial disruption of the lysosomal proton gradient, followed by the release of lysosomal hydrolases into the cytoplasmic compartment. Treatment of cells with either the antioxidant n-propyl gallate or lysosomotropic amine (methylamine) partially blocks the release of lysosomal contents suggesting that this AO relocalization is due to lysosomal membrane oxidation. Based on these findings, we propose that the cell death mediated by the soluble Abeta may be fundamentally different from the cell loss observed following extracellular Abeta deposition.

Complement component C1q modulates the phagocytosis of Abeta by microglia

Recent studies showing that microglia internalize the amyloid beta-peptide (Abeta) suggest that these cells have the potential for clearing Abeta deposits in Alzheimer's disease, and mechanisms that regulate the removal of Abeta may therefore be of clinical interest. Previous studies from this laboratory showing that C1q enhances phagocytosis of cellular targets by rat microglia prompted the current investigations characterizing the effects of C1q on microglial phagocytosis of Abeta. Microglia were shown to phagocytose Abeta1-42, in agreement with observations of other investigators. Uptake of Abeta1-42 was observed for concentrations of 5-50 microM, and phagocytosis of peptides containing (14)C or fluorescein (FM) labels was not affected by the interaction of microglia with C1q-coated surfaces. However, inclusion of C1q (125 nM-1.4 microM) in solutions of 50 microM Abeta1-42 inhibited the uptake of (14)C-Abeta1-42 and FM-Abeta1-42, suggesting that C1q blocks the interaction of Abeta with microglia. Uptake of Abeta was partially blocked by the scavenger receptor ligands polyinosinic acid and maleylated BSA. Inhibition of Abeta uptake by C1q may contribute to the accumulation of fibrillar, C1q-containing plaques that occurs in parallel with disease progression. These data suggest that mechanisms which interfere with the binding of C1q to Abeta may be of therapeutic value both through inhibition of the inflammatory events resulting from complement activation and via altered access of Abeta sites necessary for ingestion by microglia.

Intracellular accumulation of insoluble, newly synthesized abetan-42 in amyloid precursor protein-transfected cells that have been treated with Abeta1-42

Our early study indicates that intracellular Abeta1-42 aggregates are resistant to degradation and accumulate as an insoluble residue in lysosomes, where they alter the normal catabolism of amyloid precursor protein (APP) to cause the accumulation of insoluble APP and amyloidogenic fragments. In this study, we examined whether the addition of exogenous Abeta1-42 also leads to the accumulation of newly synthesized intracellular Abeta. Here we describe that newly synthesized Abeta, especially Abetan-42, is generated from metabolically labeled APP and accumulates in the insoluble fraction of cell lysates after Abeta1-42 treatment. These results suggest that intracellular Abeta may derive from a solid phase, intracellular pathway. In contrast to the pathway that primarily produces secreted Abeta1-40, the solid-phase intracellular pathway preferentially produces Abetan-42 with ragged amino termini. Biochemical studies and amino acid sequencing analyses indicate that these intracellular Abeta also share the same types of Abeta structures that accumulate in the brain of Alzheimer's disease patients, suggesting that a significant fraction of the amyloid deposits in Alzheimer's disease may arise by this solid-phase pathway.

Amyloid beta protein is internalized selectively by hippocampal field CA1 and causes neurons to accumulate amyloidogenic carboxyterminal fragments of the amyloid precursor protein

A critical issue concerning Alzheimer's disease is its selectivity, which leads to cellular degeneration in certain brain areas but not in others, and whether this pathogenic selectivity involves products of the amyloid precursor protein (APP). Here, we show that the amyloid beta protein Abeta1-42 is accumulated gradually and is retained intact by field CA1, but not by other subdivisions, of organotypic hippocampal slice cultures. In contrast, the slightly shorter Abeta1-40 peptide was not sequestered selectively. Sequestration of Abeta1-42 was followed by the build-up of carboxyterminal fragments of the endogenous precursor protein that were identified by immunoprecipitation. Unlike the peptide uptake, this induction appeared to be stochastic at the cellular level. In addition, the APP fragments were distributed more broadly within the CA1 pyramidal neurons than the sequestered Abeta1-42, and they appeared to be localized to synaptic terminals in the molecular layer of the dentate gyrus and in the stratum lacunosum-moleculare of the subfield CA3. Concentrations of synaptophysin, a presynaptic marker, decreased as the number of neurons producing amyloidogenic species increased. These results indicate that exogenous Abeta1-42 sets into motion a sequence that involves 1) selective uptake of the peptide by vulnerable cells at risk in Alzheimer's disease, 2) markedly enhanced production of amyloidogenic precursor material, and 3) slow deterioration of central synapses.

Loss of endosomal/lysosomal membrane impermeability is an early event in amyloid Abeta1-42 pathogenesis

Previous studies have implicated the failure to degrade aggregated Abeta1-42 in late endosomes or secondary lysosomes as a mechanism for the accumulation of beta-amyloid in Alzheimer's disease. We examined the consequences of intracellular accumulation of Abeta1-42 on the integrity of the endosomal/lysosomal compartment by monitoring Lucifer Yellow fluorescence and the release of lysosomal hydrolases into the soluble, cytosolic fraction. In control cells, the Lucifer Yellow fluorescence is observed as punctate staining in a perinuclear distribution with no apparent cytoplasmic fluorescence, consistent with its localization in late endosomes or secondary lysosomes. After incubation with Abeta1-42 for 6 hr, a loss of lysosomal membrane impermeability is observed as evidenced by redistribution of the fluorescence to a diffuse, cytoplasmic pattern. The loss of lysosomal membrane impermeability is correlated with Abeta1-42 accumulation, since incubation of the cells with the nonaccumulating isoform of amyloid, Abeta1-40, does not induce leakage. The same results were obtained using the release of soluble lysosomal hydrolases, cathepsin D and beta-hexosaminidase, into the cytosol as an assay for the leakage of lysosomal contents. Together, our results suggest that the loss of lysosomal membrane impermeability may be an early event in Abeta pathogenesis, and provide an explanation for the miscompartmentalization of extracellular and cytoplasmic components observed in Alzheimer's disease (AD). The release of hydrolases may further cause the breakdown of the cytoskeleton and the blebbing of the plasma membrane, and the leakage of heparan sulfate glycosaminoglycans from the lysosome may ultimately promote the assembly of tau into neurofibrillary tangles (NFT).

Presenilin-1 immunoreactivity is localized intracellularly in Alzheimer's disease brain, but not detected in amyloid plaques

The identification of the cellular and subcellular regions of the Alzheimer's disease brain to which the presenilin-1 (PS-1) protein localizes is expected to contribute to an understanding of its pathophysiological role. Toward this end, we have derived an affinity-purified antibody to a synthetic PS-1 peptide. In this report, we demonstrate that this antibody, called SW2, specifically recognizes full-length, 47-kDa PS-1 protein from rat primary cortical neurons, from a human neuronal cell line, and from human brain extracts on Western immunoblots. Immunohistochemical analysis of postmortem brain tissue from control and Alzheimer's disease patients using this SW2 antibody indicates an intracellular localization of PS-1 immunoreactivity with prominent perinuclear characteristics in neurons, with staining also detected in neuritic processes. Despite various treatments of the tissue sections, no PS-1 immunoreactivity was observed in neuritic plaques, the hallmark pathological lesions of Alzheimer's disease. In addition, confocal microscopic analysis of immunostained cultured primary neurons revealed a prominent perinuclear pattern of PS-1 immunoreactivity consistent with vesicular localization, as well as punctate staining in neuritic processes.

Identification of a 4.5S-like ribonucleoprotein in maize mitochondria

Escherichia coli has a ribonucleoprotein complex that is composed of a 114 nucleotide 4.5S RNA and a 48 kDa polypeptide (P48) that has been demonstrated to function in translation and in the secretion of periplasmic polypeptides. A small RNA of approximately 220 nucleotides has been identified in maize mitochondria that includes sequence identity with the highly conserved domain of the bacterial 4.5S RNA. The transcript is mitochondrially encoded and maps to a region upstream of the gene for ATP synthase subunit I. The mitochondrial 4.5S-like RNA has 15 nucleotides of sequence identity with the highly conserved region of the bacterial 4.5S RNA. Sucrose density gradient centrifugation of a maize mitochondrial lysate demonstrated that the 4.5S RNA is a component of a high molecular weight complex under native conditions, and could be disrupted by phenol. Anti-P48 immune serum immuno-precipitated a mitochondrial protein of approximately 48 kDa, and RNA gel blot analysis of the immunoprecipitation reaction indicated that the 4.5S-like RNA co-immuno-precipitated with the 48 kDa polypeptide. The mitochondrial 4.5S ribonucleoprotein complex could function in translation or protein targeting.

Intracellular A beta 1-42 aggregates stimulate the accumulation of stable, insoluble amyloidogenic fragments of the amyloid precursor protein in transfected cells

We have analyzed the effect of internalized amyloid beta-protein (A beta) 1-42 aggregates on the metabolism of the amyloid precursor protein (APP) in stably transfected 293 cells. The amount of potentially amyloidogenic fragments of APP immunoprecipitated by anti-carboxyl-terminal APP and anti-A beta antibodies is dramatically enhanced by the treatment of the cells with A beta 1-42, which is resistant to degradation, but not A beta 1-28, which does not accumulate in cells. This accumulation of amyloidogenic carboxyl-terminal fragments is specific, since there is relatively little effect of A beta 1-42 on the amount of the nonamyloidogenic alpha-secretase carboxyl-terminal fragment. The amyloidogenic fragments accumulate in the same nonionic detergent-insoluble fraction of the cell that contains the internalized A beta 1-42. Western analysis indicates that a subset of the amyloidogenic fragments react with antibodies that recognize a conformation of A beta that is specifically associated with aggregated forms of A beta, suggesting that the adoption of this aggregation-related conformation may be an early event which precedes the final processing that produces A beta. Pulse-chase analysis of the [35S]Met-labeled 16-kDa amyloidogenic fragment indicates that it is relatively stable in A beta 1-42-treated cells, with a half-life of approximately 50 h. This fragment is degraded with a half-life of 30 min in control cells treated with A beta 1-28. In contrast, the turnover of the nonamyloidogenic alpha-secretase product is not significantly altered by the presence of A beta 1-42. The continuous uptake of A beta 1-42 from the medium is not required for the stimulation of amyloidogenic fragment accumulation, suggesting that the presence of intracellular A beta 1-42 aggregates establishes a new pathway for APP catabolism in cells which leads to the long term stability of the fragments. If these amyloidogenic fragments of APP ultimately give rise to A beta, then the production of A beta may be an autocatalytic, "runaway" process in cells containing A beta 1-42 nuclei. It is conceivable that the accumulation of insoluble APP and amyloidogenic fragments of APP in response to A beta 1-42 aggregates may mimic the pathophysiology of dystrophic neurites, where the accumulation of intracellular APP and APP fragments has been documented by immunohistochemistry.

Distribution of maize mitochondrial transcripts in polysomal RNA: evidence for non-selectivity in recruitment of mRNAs

The distribution of maize mitochondrial transcripts in polysomal RNA fractions obtained from root tissue, shoot tissue, or isolated intact mitochondria was analyzed. The distribution of cox3 transcripts that differ in 5' untranslated RNA sequence was similar in total polysomal and total mitochondrial RNA fractions, suggesting that 5' heterogeneity does not affect recruitment of transcripts into the polysomal RNA. The distribution of spliced and unspliced cox2 transcripts was also analyzed in polysomes from total tissue or isolated mitochondria, and both precursor and mature mRNAs were present in the high-molecular-weight RNA fraction. These results suggest that ribosomal association with mitochondrial transcripts is not selective.

RNA editing intermediates of cox2 transcripts in maize mitochondria

Eighteen cytidines are changed to uridines in the coding sequence of transcripts for cytochrome c oxidase subunit 2 (cox2) in maize mitochondria. The temporal relationship of editing and splicing was examined in cox2 transcripts by sequence analysis of spliced and unspliced cDNAs. Cloned cDNAs of unspliced cox2 transcripts ranged from clones with no edited nucleotides to completely edited forms, while spliced cDNAs were nearly completely edited. Incompletely edited transcripts in the nascent pool of unspliced transcripts represent intermediates of the editing process. These results indicate that editing proceeds without a strong directional bias and suggest that RNA editing is a posttranscriptional process.