The Roles of Autophagy in Cerebral Ischemia

Recent studies indicate the existence of autophagy in cerebral ischemia, but the functions of autophagy in this setting remain unclear. Here we discuss the role of autophagy in cerebral ischemia based on our own publication and the literature on this subject. We propose that oxidative and endoplasmic reticulum (ER) stresses n cerebral ischemia-hypoxia are potent stimuli of autophagy in neurons. We also reviewed evidence suggesting autophagosomes may have a shorter half-life in neurons and that a fraction of LC3 protein is degraded within autolysosomes, leading to a smaller detectable amount of LC3-II in the brain while there are clear indications of on-going autophagy. Finally, we suggest autophagy is an important modifier of cell death and survival, interacting with necrosis and apoptosis in determining the outcomes and final morphology of deceased neurons.

Liver-directed therapies for colorectal cancer liver metastasis (CLRM): A Surveillance, Epidemiology, and End Results (SEER)-Medicare analysis

577

Background: Oligometastatic CLRM comprises a distinct subset of stage IV colorectal cancer. Liver directed therapies (LDT) including surgery, ablation, radiation, and transarterial chemotherapy/embolization have been shown to improve cancer outcomes in smaller series. We sought to evaluate utilization of LDT and their impact on survival in patients with CLRM in a population-based database. Methods: We analyzed linked SEER-Medicare data. Eligible patients were ≥ 66 years, diagnosed between 1992-2009, carry a code for secondary malignancy of the liver (ICD-9 197.7) and survived ≥ 30 days after diagnosis. LDT (yes vs. no) were defined by ICD-9 and CPT codes of surgery (hepatectomy), ablation (e.g. radiofrequency and cryoablation), radiation (e.g., stereotactic surgery and brachytherapy), and transarterial/embolization (e.g., radioembolization). Treatment and non-treatment groups were matched using a propensity score comprised of a comprehensive set of patient and tumor characteristics including: age, sex, race, marital status, Medicaid status, and tumor histology, grade, and location. Cox Proportional Hazard models were used to compare the impact of the LDT on overall survival among propensity-matched pairs of treated and untreated patients. Results: LDT were performed in 12.7% (n = 1,793) of all 14,150 patients. There were 13.7% of patients over 85 years. Females were 52.1% and 83 % White. Off all, 5.4% had surgery, 3.9% had ablation, 4.6% had radiation, and 1.6% had transarterial chemotherapy/embolization. Unadjusted 5 year overall-survival (OS) was 26.9% for those underdoing LDT vs. 7.5% who did not (HR = 0.44, (CI 0.41,0.46)). Cox modeling demonstrated a survival benefit for each LDT with HR of 0.36 (0.33,0.39) for surgery, 0.35 (0.32,0.39) for ablation, 0.78 (0.72, 0.85) for radiation and 0.42 (0.36,0.49) for transarterial/embolization. Conclusions: While use of LDT for CLRM in this national sample of Medicare patients were low, those who received treatment had markedly improved survival compared to matched patients who did not. Surgery and ablation were the most effective therapies. These findings require evaluation in a prospective clinical study.

Interleukin-15 expression in lung cancer

e21064

Background: Interleukin-15 (IL-15) is a pro-inflammatory cytokine that stimulates the differentiation and proliferation of T, B, and NK cells. IL-15 is normally tightly bound by its receptor, IL-15Rα. Dendritic cells and monocytes/macrophages primarily express both IL-15 and IL-15-Rα; however, expression has been detected on epithelial cells including those of the lung. In the lung, IL-15 is thought to play a role in the induction of immune responses to infection. Over expression of IL-15 has been shown to induce NK cell activation and cytotoxic T-lymphocyte (CTL) responses leading to tumor regression. Little is known about IL-15 or IL-15Rα expression in lung cancer. Methods: mRNA from 146 primary lung cancers were analyzed by multiplex qPCR for expression of IL-15, IL-15Rα and b-actin (internal control) and compared to expression in normal lung tissue from 45 patients. Of the 146 patients, 50 were stage I (IA=20, IB=30), 49 stage II (IIA=9, IIB=40), 36 stage III (IIIA=18, IIIB=18), and 11 stage IV. Results: Comparing the expression of IL-15 between normal lung and tumor, we found tumors expressed significantly less IL-15 than normal lung (P<0.001). Lung cancers at any given stage, expressed significantly less IL-15 than that seen in normal lung. When comparing stages, stage IV tumors expressed significantly less IL-15 than tumors of stages I (P=0.021), II (P=0.020), or III (P=0.024). There was no difference in expression between stages I, II or III (P>0.05). When examining the expression of IL-15Rα we found no differences between normal lung and tumor. No differences were seen between normal lung and stages I-IIIA; however, significantly less IL-15Rα expression was noted in stages IIIB and IV compared to normal lung. Between stages, stages I and II had significantly more IL-15Rα expression than stage IV tumors. There were no differences between stages I, II and III. Conclusions: Pro-inflammatory cytokines such as IL-15 may be important for the induction of lung immunity. IL-15 expression is down regulated in lung cancers and this down regulation increases with stage. We posit that the down regulation of IL-15 by lung cancers may aid in their evasion of immune responses allowing progression and dissemination of tumor.

Deleterious effects of plasminogen activators in neonatal cerebral hypoxia-ischemia

The immature brains of newborns often respond differently from the brains of adults when exposed to similar insults. Previous studies have indicated that although hypoxia-ischemia (HI) induces persistent thrombosis in adult brains, it only modestly impairs blood perfusion in newborn brains. Here, we used the Vannucci model of HI encephalopathy to study age-related responses to cerebral HI in rat pups. We found that HI triggered fibrin deposition and impaired blood perfusion in both neonatal and adult brains. However, these effects were only transient in neonatal brains (<4 hours) and were accompanied by acute induction of both tissue-type and urinary-type plasminogen activators (tPA and uPA), which was not observed in adult brains subjected to the same insult. Interestingly, activation of the plasminogen system persisted up to 24 hours in neonatal brains, long after the clearance of fibrin-rich thrombi. Furthermore, astrocytes and macrophages outside blood vessels expressed tPA after HI, suggesting the possibility of tPA/plasmin-mediated cytotoxicity. Consistent with this hypothesis, injection of alpha2-antiplasmin into cerebral ventricles markedly ameliorated HI-induced damage to neurofilaments and white matter oligodendrocytes, providing a dose-response reduction of brain injury after 7 days of recovery. Conversely, ventricular injection of tPA increased HI-induced brain damage. Together, these results suggest that tPA/plasmin induction, which may contribute to acute fibrinolysis, is a critical component of extravascular proteolytic damage in immature brains, representing a new therapeutic target for the treatment of HI encephalopathy.

Nestin-CreER mice reveal DNA synthesis by nonapoptotic neurons following cerebral ischemia hypoxia

The standard method of detecting neurogenesis uses bromodeoxyuridine (BrdU) to label DNA synthesis followed by double labeling with neuronal markers. However, DNA synthesis may occur in events unrelated to neurogenesis including aneuploidy and abortive cell cycle reentry. Hence, it is important to confirm neurogenesis with methods other than BrdU incorporation. To this end, we have generated transgenic nestin-CreER mice that express tamoxifen-inducible Cre recombinase under the control of a nestin enhancer. When crossed with a ubiquitous Enhanced Green Fluorescent Protein (EGFP)-Cre-reporter line, the bitransgenic animals can reveal the nestin-positive progenitors and their progeny with EGFP after tamoxifen induction. This system has many applications including visualization of embryonic neural progenitors, detection of postnatally transformed radial glial cells, and labeling adult neural progenitors in the subventricular zone (SVZ). To examine the contribution of SVZ progenitors to cell replacement after stroke, tamoxifen-induced mice were challenged with focal ischemia or combined ischemia-hypoxia followed by BrdU injection. This analysis revealed only very few EGFP-positive cells outside the SVZ after focal ischemia but robust DNA synthesis by hippocampal neurons without immediate cell death following ischemia-hypoxia. These results suggest that the nestin-CreER system is a useful tool for detecting embryonic and adult neurogensis. They also confirm the existence of nonproliferative DNA synthesis by old neurons after experimental brain injury.

Cerebral ischemia-hypoxia induces intravascular coagulation and autophagy

Hypoxia is a critical factor for cell death or survival in ischemic stroke, but the pathological consequences of combined ischemia-hypoxia are not fully understood. Here we examine this issue using a modified Levine/Vannucci procedure in adult mice that consists of unilateral common carotid artery occlusion and hypoxia with tightly regulated body temperature. At the cellular level, ischemia-hypoxia produced proinflammatory cytokines and simultaneously activated both prosurvival (eg, synthesis of heat shock 70 protein, phosphorylation of ERK and AKT) and proapoptosis signaling pathways (eg, release of cytochrome c and AIF from mitochondria, cleavage of caspase-9 and -8). However, caspase-3 was not activated, and very few cells completed the apoptosis process. Instead, many damaged neurons showed features of autophagic/lysosomal cell death. At the tissue level, ischemia-hypoxia caused persistent cerebral perfusion deficits even after release of the carotid artery occlusion. These changes were associated with both platelet deposition and fibrin accumulation within the cerebral circulation and would be expected to contribute to infarction. Complementary studies in fibrinogen-deficient mice revealed that the absence of fibrin and/or secondary fibrin-mediated inflammatory processes significantly attenuated brain damage. Together, these results suggest that ischemia-hypoxia is a powerful stimulus for spontaneous coagulation leading to reperfusion deficits and autophagic/lysosomal cell death in brain.

Cloning and molecular characterization of the Hevea brasiliensis allergen Hev b 11, a class I chitinase

BACKGROUND

In the last 10 years type-I allergy against proteins from Hevea brasiliensis latex has become an acknowledged medical issue. Fruit-allergic patients represent one risk group for developing latex allergy. Class I chitinases have been identified from chestnut, avocado and banana as relevant allergens. The chitin binding (hevein) domain from these class I chitinases has been postulated to bear the important IgE binding epitopes.

OBJECTIVE

To clone the cDNA of an allergenic latex class I chitinase, to express the recombinant protein and to determine its IgE cross-reactivity with hevein (Hev b 6.02).

METHODS

A full-length cDNA coding for a class I chitinase has been isolated from Hevea latex RNA by reverse transcription followed by PCR. The chitinase encoding sequence has been subcloned into the pMAL expression vector and expressed in E. coli as a fusion protein to maltose binding protein. The highly enriched recombinant protein fraction has been tested for its IgE binding capacity in immunoblots and ELISA. Furthermore, the pathogenesis-related function of the recombinant protein was tested in a fungal growth inhibition assay.

RESULTS

The Hevea brasiliensis latex chitinase, designated Hev b 11, displays 70% identity to the endochitinase from avocado and its hevein-domain 58% to hevein (Hev b 6.02). The recombinant Hev b 11-maltose binding protein is recognized by latex- and fruit-allergic patients with IgE binding in both, ELISA and immunoblots. Pre-incubation of sera with rHev b 11-maltose binding protein showed an overall 16% inhibition of subsequent binding to rHev b 6.02-maltose binding protein on solid phase. The growth of F. oxysporum was inhibited in a dose dependent manner by addition of rHev b 11-maltose binding protein to the culture.

CONCLUSIONS

Hev b 11, a class I chitinase, is another allergen from Hevea latex with a chitin binding domain and displays a different IgE binding capacity compared with hevein.

Bilateral recession-resection surgery for convergent strabismus fixus associated with high myopia

The authors report two patients with more than 20 diopters of myopia, severely restricted abduction, and more than 90Delta of acquired esotropia. Marked axial elongation of the globes was present. Each underwent large bilateral medial rectus recessions and bilateral lateral rectus resections. The deviations were significantly reduced and abduction improved with combined horizontal recession-resection surgery on both eyes.

Robust gut-specific gene expression in transgenic Aedes aegypti mosquitoes

Genetic modification of the vectorial capacity of mosquito vectors of human disease requires promoters capable of driving gene expression with appropriate tissue and stage specificity. We report on the characterization in transgenic Aedes aegypti of two mosquito gut-specific promoters. A 1.4-kb DNA fragment adjacent to the 5' end of the coding region of the Ae. aegypti carboxypeptidase (AeCP) gene and a corresponding 3.4-kb DNA fragment at the 5' end of the Anopheles gambiae carboxypeptidase (AgCP) gene were linked to a firefly luciferase reporter gene and introduced into the Ae. aegypti germ line by using Hermes and mariner (Mos1) transposons. Six independent transgenic lines were obtained with the AeCP construct and one with the AgCP construct. Luciferase mRNA and protein were abundantly expressed in the guts of transgenic mosquitoes in four of the six AeCP lines and in the AgCP line. Expression of the reporter gene was gut-specific and reached peak levels at about 24 h post-blood ingestion. The AeCP and AgCP promoters can be used to drive the expression of genes that hinder parasite development in the mosquito gut.

Nonradioactive labeling of large DNA fragments for genome walking, RFLP and northern blot analysis

In this report, we present a simple nonradioactive labeling procedure for DNA fragments of high specific labeling density that can be used for a variety of applications. The protocol is based on the universal mono-functional platinum reagent for chemical digoxigenin (DIG) labeling of nucleic acids. The labeling protocol was optimized for large DNA templates as complete bacterial artificial chromosomes (BAC). Variations of incubation time and temperature improved the labeling density such that about 30% of the nucleotides were DIG-modified within 30 min. Furthermore, the refined procedure generates in a single-tube reaction and without prior digestion-labeled DNA fragments of 0.5-4.0 kb from a 130-kb template. Hybridization experiments were performed on Southern and northern blots and allowed the detection of single copy genes in 2.5 micrograms genomic DNA from Arabidopsis thaliana, which has a haploid genome size of 0.13 pg (ca. 120 Mb) and medium expressed transcripts from 0.8 microgram poly(A)+ RNA, respectively. The extremely high specific labeling density, the stability and the universal application of the probe generated with the platinum reagent makes this method a useful alternative to classical radioactive nuclei acids labeling techniques.

Generation of co-dominant PCR-based markers by duplex analysis on high resolution gels

Rapid and efficient procedures for the detection of sequence polymorphisms are essential for chromosomal walking and mutation detection analyses. While DNA chip technology and denaturing high-performance liquid chromatography (DHPLC) are the methods of choice for large scale facilities, small laboratories are dependent on simple ready-to-use techniques. We show that heteroduplex analysis on high resolution gel matrices efficiently detects sequence polymorphism differing as little as a single base pair (e.g. single-nucleotide polymorphism, SNP) with standard laboratory equipment. Furthermore, the matrices also discerned differences between homoduplexes, a prerequisite for co-dominant markers. The markers thus generated are referred to as duplex analysis markers. We designed PCR primers for 36 Arabidopsis thaliana loci ranging in length from 230 bp to 1000 bp. Among three ecotypes, more than half (n = 19) of the loci examined were polymorphic; five of which contained three different alleles. This simple, high resolution technique can be used to rapidly convert sequence tagged sites into co-dominant PCR-based molecular markers for fine-scale mapping studies and chromosomal walking strategies as well as for the detection of mutations in particular genes.