Ferroptosis: process and function

Ferroptosis is a recently recognized form of regulated cell death. It is characterized morphologically by the presence of smaller than normal mitochondria with condensed mitochondrial membrane densities, reduction or vanishing of mitochondria crista, and outer mitochondrial membrane rupture. It can be induced by experimental compounds (e.g., erastin, Ras-selective lethal small molecule 3, and buthionine sulfoximine) or clinical drugs (e.g., sulfasalazine, sorafenib, and artesunate) in cancer cells and certain normal cells (e.g., kidney tubule cells, neurons, fibroblasts, and T cells). Activation of mitochondrial voltage-dependent anion channels and mitogen-activated protein kinases, upregulation of endoplasmic reticulum stress, and inhibition of cystine/glutamate antiporter is involved in the induction of ferroptosis. This process is characterized by the accumulation of lipid peroxidation products and lethal reactive oxygen species (ROS) derived from iron metabolism and can be pharmacologically inhibited by iron chelators (e.g., deferoxamine and desferrioxamine mesylate) and lipid peroxidation inhibitors (e.g., ferrostatin, liproxstatin, and zileuton). Glutathione peroxidase 4, heat shock protein beta-1, and nuclear factor erythroid 2-related factor 2 function as negative regulators of ferroptosis by limiting ROS production and reducing cellular iron uptake, respectively. In contrast, NADPH oxidase and p53 (especially acetylation-defective mutant p53) act as positive regulators of ferroptosis by promotion of ROS production and inhibition of expression of SLC7A11 (a specific light-chain subunit of the cystine/glutamate antiporter), respectively. Misregulated ferroptosis has been implicated in multiple physiological and pathological processes, including cancer cell death, neurotoxicity, neurodegenerative diseases, acute renal failure, drug-induced hepatotoxicity, hepatic and heart ischemia/reperfusion injury, and T-cell immunity. In this review, we summarize the regulation mechanisms and signaling pathways of ferroptosis and discuss the role of ferroptosis in disease.

The Beclin 1 network regulates autophagy and apoptosis

Beclin 1, the mammalian orthologue of yeast Atg6, has a central role in autophagy, a process of programmed cell survival, which is increased during periods of cell stress and extinguished during the cell cycle. It interacts with several cofactors (Atg14L, UVRAG, Bif-1, Rubicon, Ambra1, HMGB1, nPIST, VMP1, SLAM, IP(3)R, PINK and survivin) to regulate the lipid kinase Vps-34 protein and promote formation of Beclin 1-Vps34-Vps15 core complexes, thereby inducing autophagy. In contrast, the BH3 domain of Beclin 1 is bound to, and inhibited by Bcl-2 or Bcl-XL. This interaction can be disrupted by phosphorylation of Bcl-2 and Beclin 1, or ubiquitination of Beclin 1. Interestingly, caspase-mediated cleavage of Beclin 1 promotes crosstalk between apoptosis and autophagy. Beclin 1 dysfunction has been implicated in many disorders, including cancer and neurodegeneration. Here, we summarize new findings regarding the organization and function of the Beclin 1 network in cellular homeostasis, focusing on the cross-regulation between apoptosis and autophagy.

HSPB1 as a novel regulator of ferroptotic cancer cell death

Ferroptosis is an iron-dependent form of non-apoptotic cell death, but its molecular mechanism remains largely unknown. Here, we demonstrate that heat shock protein beta-1 (HSPB1) is a negative regulator of ferroptotic cancer cell death. Erastin, a specific ferroptosis-inducing compound, stimulates heat shock factor 1 (HSF1)-dependent HSPB1 expression in cancer cells. Knockdown of HSF1 and HSPB1 enhances erastin-induced ferroptosis, whereas heat shock pretreatment and overexpression of HSPB1 inhibits erastin-induced ferroptosis. Protein kinase C-mediated HSPB1 phosphorylation confers protection against ferroptosis by reducing iron-mediated production of lipid reactive oxygen species. Moreover, inhibition of the HSF1-HSPB1 pathway and HSPB1 phosphorylation increases the anticancer activity of erastin in human xenograft mouse tumor models. Our findings reveal an essential role for HSPB1 in iron metabolism with important effects on ferroptosis-mediated cancer therapy.

Release and activity of histone in diseases

Histones and their post-translational modifications have key roles in chromatin remodeling and gene transcription. Besides intranuclear functions, histones act as damage-associated molecular pattern molecules when they are released into the extracellular space. Administration of exogenous histones to animals leads to systemic inflammatory and toxic responses through activating Toll-like receptors and inflammasome pathways. Anti-histone treatment (e.g., neutralizing antibodies, activated protein C, recombinant thrombomodulin, and heparin) protect mice against lethal endotoxemia, sepsis, ischemia/reperfusion injury, trauma, pancreatitis, peritonitis, stroke, coagulation, and thrombosis. In addition, elevated serum histone and nucleosome levels have been implicated in multiple pathophysiological processes and progression of diseases including autoimmune diseases, inflammatory diseases, and cancer. Therefore, extracellular histones could serve as biomarkers and novel therapeutic targets in human diseases.

Direct adenovirus-mediated gene transfer of interleukin 1 and tumor necrosis factor alpha soluble receptors to rabbit knees with experimental arthritis has local and distal anti-arthritic effects

Adenoviral vectors were used to deliver genes encoding a soluble interleukin 1 (IL-1)-type I receptor-IgG fusion protein and/or a soluble type I tumor necrosis factor alpha (TNFalpha) receptor-IgG fusion protein directly to the knees of rabbits with antigen-induced arthritis. When tested individually, knees receiving the soluble IL-1 receptor had significantly reduced cartilage matrix degradation and white blood cell infiltration into the joint space. Delivery of the soluble TNFalpha receptor was less effective, having only a moderate effect on white blood cell infiltration and no effect on cartilage breakdown. When both soluble receptors were used together, there was a greater inhibition of white blood cell infiltration and cartilage breakdown with a considerable reduction of synovitis. Interestingly, anti-arthritic effects were also seen in contralateral control knees receiving only a marker gene, suggesting that sustained local inhibition of disease activity in one joint may confer an anti-arthritic effect on other joints. These results suggest that local intra-articular gene transfer could be used to treat systemic polyarticular arthritides.

The HMGB1/RAGE inflammatory pathway promotes pancreatic tumor growth by regulating mitochondrial bioenergetics

Tumor cells require increased adenosine triphosphate (ATP) to support anabolism and proliferation. The precise mechanisms regulating this process in tumor cells are unknown. Here, we show that the receptor for advanced glycation endproducts (RAGE) and one of its primary ligands, high-mobility group box 1 (HMGB1), are required for optimal mitochondrial function within tumors. We found that RAGE is present in the mitochondria of cultured tumor cells as well as primary tumors. RAGE and HMGB1 coordinately enhanced tumor cell mitochondrial complex I activity, ATP production, tumor cell proliferation and migration. Lack of RAGE or inhibition of HMGB1 release diminished ATP production and slowed tumor growth in vitro and in vivo. These findings link, for the first time, the HMGB1-RAGE pathway with changes in bioenergetics. Moreover, our observations provide a novel mechanism within the tumor microenvironment by which necrosis and inflammation promote tumor progression.

Targeting microRNA-30a-mediated autophagy enhances imatinib activity against human chronic myeloid leukemia cells

A major advancement in the treatment of chronic myeloid leukemia (CML) has been the development of imatinib and other BCR-ABL tyrosine kinase inhibitors. MicroRNAs (miRNAs) are small RNA molecules that influence gene expression by post-transcriptional regulation of messenger RNA. It is not yet clear how miRNAs are able to regulate the effectiveness of imatinib in CML. Here, we show that imatinib markedly inhibits expression of miR-30a in human CML cells. miR-30a is a potent inhibitor of autophagy by downregulating Beclin 1 and ATG5 expression. miR-30a mimic or knockdown of autophagy genes (ATGs) such as Beclin 1 and ATG5 by short hairpin RNA enhances imatinib-induced cytotoxicity and promotes mitochondria-dependent intrinsic apoptosis. In contrast, knockdown of miR-30a by antagomir-30a increases the expression of Beclin 1 and ATG5, and inhibits imatinib-induced cytotoxicity. These findings indicate that dysregulation of miR-30a may interfere with the effectiveness of imatinib-mediated apoptosis by an autophagy-dependent pathway, thus representing a novel potential therapeutic target in CML.

Strange attractors: DAMPs and autophagy link tumor cell death and immunity

Resistance to ‘apoptotic' cell death is one of the major hallmarks of cancer, contributing to tumor development and therapeutic resistance. Damage-associated molecular patterns (DAMPs) are molecules released or exposed by dead, dying, injured, or stressed non-apoptotic cells, with multiple roles in inflammation and immunity. Release of DAMPs not only contributes to tumor growth and progression but also mediates skewing of antitumor immunity during so-called immunogenic tumor cell death (ICD). Autophagy is a lysosome-mediated homeostatic degradation process in which cells digest their own effete organelles and macromolecules to meet bioenergetic needs and enable protein synthesis. For tumor cells, autophagy is a double-edged sword. Autophagy, in balance with apoptosis, can function as a tumor suppressor; autophagy deficiency, associated with alterations in apoptosis, initiates tumorigenesis in many settings. In contrast, autophagy-related stress tolerance generally promotes cell survival, which enables tumor growth and promotes therapeutic resistance. Most anticancer therapies promote DAMP release and enhance autophagy. Autophagy not only regulates DAMP release and degradation, but also is triggered and regulated by DAMPs. This interplay between autophagy and DAMPs, serving as ‘strange attractors' in the dynamic system that emerges in cancer, regulates the effectiveness of antitumor treatment. This interplay also shapes the immune response to dying cells upon ICD, culling the least fit tumor cells and promoting survival of others. Thus, DAMPs and autophagy are suitable emergent targets for cancer therapy, considering their more nuanced role in tumor progression.

Factors Associated With Major Adverse Cardiovascular Events After Liver Transplantation Among a National Sample

Assessment of major adverse cardiovascular events (MACE) after liver transplantation (LT) has been limited by the lack of a multicenter study with detailed clinical information. An integrated database linking information from the University HealthSystem Consortium and the Organ Procurement and Transplant Network was analyzed using multivariate Poisson regression to assess factors associated with 30- and 90-day MACE after LT (February 2002 to December 2012). MACE was defined as myocardial infarction (MI), heart failure (HF), atrial fibrillation (AF), cardiac arrest, pulmonary embolism, and/or stroke. Of 32 810 recipients, MACE hospitalizations occurred in 8% and 11% of patients at 30 and 90 days, respectively. Recipients with MACE were older and more likely to have a history of nonalcoholic steatohepatitis (NASH), alcoholic cirrhosis, MI, HF, stroke, AF and pulmonary and chronic renal disease than those without MACE. In multivariable analysis, age >65 years (incidence rate ratio [IRR] 2.8, 95% confidence interval [95% CI] 1.8-4.4), alcoholic cirrhosis (IRR 1.6, 95% CI 1.2-2.2), NASH (IRR 1.6, 95% CI 1.1-2.4), pre-LT creatinine (IRR 1.1, 95% CI 1.04-1.2), baseline AF (IRR 6.9, 95% CI 5.0-9.6) and stroke (IRR 6.3, 95% CI 1.6-25.4) were independently associated with MACE. MACE was associated with lower 1-year survival after LT (79% vs. 88%, p < 0.0001). In a national database, MACE occurred in 11% of LT recipients and had a negative impact on survival. Pre-LT AF and stroke substantially increase the risk of MACE, highlighting potentially high-risk LT candidates.

The receptor for advanced glycation end products (RAGE) enhances autophagy and neutrophil extracellular traps in pancreatic cancer

Neutrophil extracellular traps (NETs) are formed when neutrophils expel their DNA, histones and intracellular proteins into the extracellular space or circulation. NET formation is dependent on autophagy and is mediated by citrullination of histones to allow for unwinding and subsequent expulsion of DNA. NETs play an important role in the pathogenesis of several sterile inflammatory diseases, including malignancy, therefore we investigated the role of NETs in the setting of pancreatic ductal adenocarcinoma (PDA). Neutrophils isolated from two distinct animal models of PDA had an increased propensity to form NETs following stimulation with platelet activating factor (PAF). Serum DNA, a marker of circulating NET formation, was elevated in tumor bearing animals as well as in patients with PDA. Citrullinated histone H3 expression, a marker of NET formation, was observed in pancreatic tumors obtained from murine models and patients with PDA. Inhibition of autophagy with chloroquine or genetic ablation of RAGE resulted in decreased propensity for NET formation, decreased serum DNA, and decreased citrullinated histone H3 expression in the pancreatic tumor microenvironment. We conclude that NETs are upregulated in pancreatic cancer through RAGE dependent/autophagy pathways.

Transcriptional regulation of the N-acetylglucosaminyltransferase V gene in human bile duct carcinoma cells (HuCC-T1) is mediated by Ets-1

N-Acetylglucosaminyltransferase V (GnT-V) catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to alpha-6-D-mannoside to produce the beta1-6 linked branching of N-glycan oligosaccharides, which controls the polylactosamine content. The expression of N-acetylglucosaminyltransferase V, which contains 17 exons and spans 155 kilobase pairs, is expressed in a tissue- and cell type-specific manner and is regulated at the level of transcription by multiple promoters (Saito, H., Gu, J., Nishikawa, A., Ihara, Y., Fujii, J., Kohgo, Y., and Taniguchi, N. (1995) Eur. J. Biochem. 233, 18-26). To elucidate the mechanism by which the GnT-V gene is expressed in a cell- and tissue-specific manner, cell-restricted expression was analyzed using the 5'-upstream regions of the human GnT-V gene spanning base pairs -2760 to +23 in a human bile duct carcinoma cell line, HuCC-T1. We characterized two cis-acting elements that are potentially important in HuCC-T1 cell-specific expression. The two elements each contain an Ets-1 binding site, 5'-GGA-3'. Specific binding of Ets-1 to the respective elements was demonstrated by competition analysis as well as by antibody supershift experiments. Cotransfection of an Ets-1 expression plasmid along with a GnT-V promoter-luciferase reporter plasmid revealed the participation of Ets-1 in the regulation of the GnT-V gene transcription. These data indicated that the transcriptional regulation of the GnT-V gene was mediated by transcription factor Ets-1.

Regulation of the GnT-V promoter by transcription factor Ets-1 in various cancer cell lines

Although the precise role of oligosaccharides in metastasis is presently unknown, numerous studies suggest that the beta1-6 branching structure of N-linked oligosaccharides plays a role in tumor metastasis. N-Acetylglucosaminyltransferase V (GnT-V), which catalyzes the formation of the beta1-6 branch, therefore appears to play a crucial role in tumor metastasis. Recently, we demonstrated that the expression of the GnT-V gene is regulated by a transcriptional factor, Ets-1 (Kang, R., Saito, H., Ihara, Y., Miyoshi, E., Koyama, N., Sheng, Y., and Taniguchi, N. (1996) J. Biol. Chem. 271, 26706-26712). In this study, we report an investigation of the general requirement for Ets-1 in the expression of GnT-V in cancer cell lines. In 16 cancer cell lines, the levels of GnT-V mRNA were closely correlated with ets-1 expression (r = 0.97; p < 0.0001). An increase in ets-1 levels by transfection of its cDNA led to an enhancement in GnT-V expression in cells that normally expressed low levels of ets-1. In contrast, the transfection of dominant negative ets-1 into cells that express high levels of ets-1 resulted in a decrease in GnT-V expression. Although Ets-1 cooperates with c-Jun in certain gene expressions, this was not the case in the regulation of the GnT-V gene. These results suggest that Ets-1 plays a significant role in regulating the expression of GnT-V in a variety of cancers and might be involved in the potential for malignancy via the action of GnT-V.

RAGE is essential for oncogenic KRAS-mediated hypoxic signaling in pancreatic cancer

A hypoxic tumor microenvironment is characteristic of many cancer types, including one of the most lethal, pancreatic cancer. We recently demonstrated that the receptor for advanced glycation end products (RAGE) has an important role in promoting the development of pancreatic cancer and attenuating the response to chemotherapy. We now demonstrate that binding of RAGE to oncogenic KRAS facilitates hypoxia-inducible factor 1 (HIF1)α activation and promotes pancreatic tumor growth under hypoxic conditions. Hypoxia induces NF-κB-dependent and HIF1α-independent RAGE expression in pancreatic tumor cells. Moreover, the interaction between RAGE and mutant KRAS increases under hypoxia, which in turn sustains KRAS signaling pathways (RAF-MEK-ERK and PI3K-AKT), facilitating stabilization and transcriptional activity of HIF1α. Knock down of RAGE in vitro inhibits KRAS signaling, promotes HIF1α degradation, and increases hypoxia-induced pancreatic tumor cell death. RAGE-deficient mice have impaired oncogenic KRAS-driven pancreatic tumor growth with significant downregulation of the HIF1α signaling pathway. Our results provide a novel mechanistic link between NF-κB, KRAS, and HIF1α, three potent molecular pathways in the cellular response to hypoxia during pancreatic tumor development and suggest alternatives for preventive and therapeutic strategies.

Entry of Escherichia coli into stationary phase is indicated by endogenous and exogenous accumulation of nucleobases

Endogenous and exogenous accumulation of nucleobases was observed when Escherichia coli entered the stationary phase. The onset of the stationary phase was accompanied by excretion of uracil and xanthine. Except for uracil and xanthine, other nucleobases (except for minor amounts of hypoxanthine), nucleosides, and nucleotides (except for cyclic AMP) were not detected in significant amounts in the culture medium. In addition to exogenous accumulation of nucleobases, stationary-phase cells increased the endogenous concentrations of free nucleobases. In contrast to extracellular nucleobases, hypoxanthine was the dominating intracellular nucleobase and xanthine was present only in minor concentrations inside the cells. Excretion of nucleobases was always connected to declining growth rates. It was observed in response to entry into the stationary phase independent of the initial cause of the cessation of cell growth (e.g., starvation for essential nutrients). In addition, transient accumulation of exogenous nucleobases was observed during perturbations of balanced growth conditions such as energy source downshifts. The nucleobases uracil and xanthine are the final breakdown products of pyrimidine (uracil and cytosine) and purine (adenine and guanine) bases, respectively. Hypoxanthine is the primary degradation product of adenine, which is further oxidized to xanthine. The endogenous and exogenous accumulation of these nucleobases in response to entry into the stationary phase is attributed to degradation of rRNA.

Isoflurane pretreatment ameliorates postischemic neurologic dysfunction and preserves hippocampal Ca2+/calmodulin-dependent protein kinase in a canine cardiac arrest model

BACKGROUND

Inhalational anesthetics are neuroprotective in rat models of global ischemia. To determine whether isoflurane at a clinically relevant concentration is neuroprotective in a canine model of cardiac arrest, we measured neurologic function and hippocampal Ca2+/calmodulin-dependent protein kinase II (CaMKII) content 20 h after cardiac arrest.

METHODS

We tested the neuroprotective effect of 30 min of 1.5% isoflurane exposure before 8 min of global ischemia induced with ventricular fibrillation. Animals were randomized to four groups: control, isoflurane-control, ischemia, and isoflurane-ischemia. After resuscitation and 20 h of intensive care, each animal's neurologic deficit score was determined by two blinded evaluators. The hippocampal content of CaMKII, determined by immunoblotting, was measured by an individual blinded to the treatment groups. CaMKII activity was measured in samples from the cortex, hippocampus, and striatum of animals in each group.

RESULTS

Isoflurane-ischemic animals had a median neurologic deficit score of 22.6% compared with 43.8% for the ischemic animals (P < 0.05). Hippocampal levels of the beta-subunit of CaMKII (CaMKIIbeta) were relatively preserved in isoflurane-ischemic animals (68 +/- 4% of control) compared with ischemic animals (48 +/- 2% of control; P < 0.001), although both groups were statistically significantly lower than control (P < 0. 001 ischemia vs. control and P < 0.05 isoflurane-ischemia vs. control).

CONCLUSIONS

Isoflurane is an effective neuroprotective drug in a canine cardiac arrest model in terms of both functional and biochemical criteria.

Examining Timeliness of Total Knee Replacement Among Patients with Knee Osteoarthritis in the U.S.: Results from the OAI and MOST Longitudinal Cohorts

BACKGROUND

Patients with knee osteoarthritis may undergo total knee replacement too early or may delay or underuse this procedure. We quantified these categories of total knee replacement utilization in 2 cohorts of participants with knee osteoarthritis and investigated factors associated with each category.

METHODS

Data were pooled from 2 multicenter cohort studies that collected demographic, patient-reported, radiographic, clinical examination, and total knee replacement utilization information longitudinally on 8,002 participants who had or were at risk for knee osteoarthritis and were followed for up to 8 years. Validated total knee replacement appropriateness criteria were longitudinally applied to classify participants as either potentially appropriate or likely inappropriate for total knee replacement. Participants were further classified on the basis of total knee replacement utilization into 3 categories: timely (indicating that the patient had total knee replacement within 2 years after the procedure had become potentially appropriate), potentially appropriate but knee not replaced (indicating that the knee had remained unreplaced for >2 years after the procedure had become potentially appropriate), and premature (indicating that the procedure was likely inappropriate but had been performed). Utilization rates were calculated, and factors associated with each category were identified.

RESULTS

Among 8,002 participants, 3,417 knees fulfilled our inclusion and exclusion criteria and were classified into 1 of 3 utilization categories as follows: 290 knees (8% of the total and 9% of the knees for which replacement was potentially appropriate) were classified as "timely", 2,833 knees (83% of the total and 91% of those for which replacement was potentially appropriate) were classified as "potentially appropriate but not replaced", and 294 knees (comprising 9% of the total and 26% of the 1,114 total knee replacements performed) were considered to be "likely inappropriate" yet underwent total knee replacement and were classified as "premature". Of the knees that were potentially appropriate but were not replaced, 1,204 (42.5%) had severe symptoms. Compared with the patients who underwent timely total knee replacement, the likelihood of being classified as potentially appropriate but not undergoing total knee replacement was greater for black participants and the likelihood of having premature total knee replacement was lower among participants with a body mass index of >25 kg/m and those with depression.

CONCLUSIONS

In 2 multicenter cohorts of patients with knee osteoarthritis, we observed substantial numbers of patients who had premature total knee replacement as well as of patients for whom total knee replacement was potentially appropriate but had not been performed >2 years after it had become potentially appropriate. Further understanding of these observations is needed, especially among the latter group.

CLINICAL RELEVANCE

Undergoing total knee replacement too early may result in little or no benefit while exposing the patient to the risks of a major operation, whereas waiting too long may cause limitations in physical activity that in turn increase the risk of additional disability and chronic disease; however, little is known about timing of this surgery. We quantified the extent of premature, timely, and delayed use, and found a high prevalence of both premature and delayed use.

Mortality Risk Factors Among Patients With Cirrhosis and a Low Model for End-Stage Liver Disease Sodium Score (≤15): An Analysis of Liver Transplant Allocation Policy Using Aggregated Electronic Health Record Data

Although the Model for End-Stage Liver Disease sodium (MELD Na) score is now used for liver transplant allocation in the United States, mortality prediction may be underestimated by the score. Using aggregated electronic health record data from 7834 adult patients with cirrhosis, we determined whether the cause of cirrhosis or cirrhosis complications was associated with an increased risk of death among patients with a MELD Na score ≤15 and whether patients with the greatest risk of death could benefit from liver transplantation (LT). Over median follow-up of 2.3 years, 3715 patients had a maximum MELD Na score ≤15. Overall, 3.4% were waitlisted for LT. Severe hypoalbuminemia, hepatorenal syndrome, and hepatic hydrothorax conferred the greatest risk of death independent of MELD Na score with 1-year predicted mortality >14%. Approximately 10% possessed these risk factors. Of these high-risk patients, only 4% were waitlisted for LT, despite no difference in nonliver comorbidities between waitlisted patients and those not listed. In addition, risk factors for death among waitlisted patients were the same as those for patients not waitlisted, although the effect of malnutrition was significantly greater for waitlisted patients (hazard ratio 8.65 [95% CI 2.57-29.11] vs. 1.47 [95% CI 1.08-1.98]). Using the MELD Na score for allocation may continue to limit access to LT.

Gene transfer to the patellar tendon

Growth factors have the potential to enhance native repair responses in ligamentous lesions. However, methods for applying these cytokines to sites of injury for extended periods are lacking. We suggest that local transfer of genes which encode the relevant healing factors merits investigation as a potential solution to this problem. In the present study, the retroviral vectors MFG lacZ and BAG lacZ neo(r) and adenovirus LacZ were evaluated for their ability to deliver genes to cells of ligamentous origin. The posterior and anterior cruciate ligaments, medial collateral ligament, semitendinosus tendon and patellar tendon were harvested from New Zealand white rabbits. Cells grown from these tissues were then investigated for their susceptibility to genetic alteration by these vectors in vitro. Based upon their ability to convert cells in culture to a lacZ(+) phenotype, adenovirus was the most effective vector in short-term experiments. However, expression was transient. Although retrovirus gave lower initial transduction efficiencies, the percentage of transduced cells could be increased by the use of the selectable marker gene neo(r). In an in vivo marker study, we injected adenovirus into the rabbit patellar tendon. Transduced cells could be observed preferentially in the subsynovial layer at a declining frequency over a 6-week period. The allogeneic transplantation of in vitro retrovirally transduced fibroblasts into the patellar tendon resulted in a greater number of transduced cells. Although the number of lacZ(+) cells declined with time, positive cells were still present 6 weeks after transplantation. Furthermore, the transplanted cells, unlike cells transduced in situ with adenovirus, migrated from the injection site and integrated into the crimp of the tendon.

Preterm infant follow-up project: a multi-site field experiment of hospital and home intervention programs for mothers and preterm infants

This study was designed as a multi-site field experiment to test the efficacy of hospital and home visit interventions to improve interaction between mothers and preterm infants. Hospital intervention consisted of State Modulation (SM) treatment, which focused on teaching mothers to read the behavioral cues and modulate the states of consciousness of preterm infants during feedings. Home visit intervention was a field-tested program, Nursing Systems for Effective Parenting-Preterm (NSTEP-P), implemented during the first five months after the infant's hospital discharge. A hospital program on car seats (CS) and standard public health nursing home visits (PHN) served as comparison treatments. The sample consisted of 327 mothers and their preterm infants who were less than 36 weeks of gestational age at hospital discharge. Mothers were randomly assigned to intervention groups on the basis of their education. High education (HE) was > or = 13 years of education, while low education (LE) was < or = 12 years of education. HE mothers were only assigned to hospital programs, while LE mothers were assigned to combinations of hospital and home visit programs. Evaluations were conducted at 40 weeks conceptual age (expected date of birth), at 46 weeks conceptual age (1.5-months-corrected age), and 60 weeks conceptual age (5-months-corrected age). Comparisons were made within each educational group. For HE groups, SM infants gave significantly more clear cues during observations of feeding interactions at 1.5-months-corrected age and teaching interactions at 5-months-corrected age than infants in the CS group. During the teaching interaction, well-educated SM mothers provided significantly more social-emotional and cognitive stimulation than CS mothers. For LE groups, infants in the SM group combined with either PHN or NSTEP-P exhibited significantly more responsive behavior during feeding observations than those infants in the CS/PHN group at 1.5-months-corrected age. LE mothers in the SM/NSTEP-P group demonstrated more sensitivity and more stimulation during teaching interactions at 5-months-corrected age than mothers in the SM/PHN or CS/PHN groups. Findings suggest that State Modulation treatment is effective in influencing positive social interaction of infants regardless of the level of maternal education. State modulation treatment combined with NSTEP-P is most effective in improving the social interaction between preterm infants and mothers with limited formal education. Such treatment-specific programs suggest avenues for providing cost-effective care that complements the changing transactional needs of mothers and preterm infants.

Effect of age on atherogenicity of LDL and inflammatory markers in healthy women

BACKGROUND AND AIM

Since using LDL level alone is insufficient as a method to identify individuals with incident coronary artery disease (CAD), other factors may be implicated in the pathogenesis of CAD. Additionally, controversy still remains regarding whether there is an age-related increase in circulating cytokines in healthy individuals. We investigated the influence of age on atherogenicity of LDL and inflammatory markers in healthy women.

METHODS AND RESULTS

Two thousand nine hundred forty four healthy women form 30-79 years old (23.3 ± 0.05 kg/m²) were categorized into 5 age groups: 30-39, 40-49, 50-59, 60-69 and 70-79 years. BMI, smoking, drinking, and metabolic syndrome prevalence adjusted mean values of total-cholesterol progressively increased from the group age 30-39 years to the group age 40-49 and 50-59 years and thereafter decreased in the group age 60-69 and 70-79 years. Serum concentrations of C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were higher in women aged 60-79 years than women aged 30-59 years. Plasma ox-LDL levels increased in the group age 50-59 years compared with the group age 30-39 and 40-49 years and further increased in the group age 60-69 and 70-79 years. Mean values of LDL particle size were smaller in women aged 60-79 years than those in women aged 30-59 years. After adjustment for BMI, smoking, drinking, and metabolic syndrome status, age was positively correlated with LDL-cholesterol (r = 0.095, P < 0.001), oxidized LDL (r = 0.305, P < 0.001), hs-CRP (r = 0.150, P < 0.001), TNF-α (r = 0.171, P < 0.001) and IL-6 (r = 0.294, P < 0.001) and negatively with LDL particle size (r = -0.239, P < 0.001).

CONCLUSION

Our results indicate that LDL atherogenicity and inflammatory mediators can be better markers of CAD risk than known risk factors such as elevated concentrations of total- and LDL-cholesterol, decreased HDL-cholesterol levels and smoking in old healthy women.

Convergence of sensory inputs in somatosensory cortex: interactions from separate afferent sources

Intracellular recording techniques were used to test for cross-modality and topographic convergence among inputs to area 3a of cerebral cortex. Recordings were made within the projection area of group I afferent fibers of the deep radial nerve in barbiturate-anesthetized cats. Epsps were evoked in 90% of neurons (81/90) by electrical stimulation of more than one nerve of the contralateral forelimb. The deep radial nerve evoked the shortest latency epsps within this region of cortex and the only ones likely to be mediated by a monosynaptic thalamocortical pathway. However, the epsps evoked from other forelimb nerves (of deep or cutaneous origin) had mean latencies only a few milliseconds (1.3-3.0 ms) longer. Furthermore, there were a variety of interactions among inputs from separate afferent sources. The observed interactions included spatial facilitation, occlusion and afferent inhibition. The consequence of these interactions was that neuronal responses were shaped by combinations of effects from different topographic regions of the forelimb or of different modalities. The findings are interpreted as indicating a sharing of neurons among pathways to cortical neurons from separate afferent sources. Interactions between ascending pathways by way of such shared neurons may contribute to the modulation or plasticity of somatosensory responsiveness during behavior or after deafferentation.

Alternative splicing of the pyruvate kinase M gene in a minigene system

The M1-type and M2-type isozymes of pyruvate kinase are produced from a single gene by mutually exclusive use of exons 9 and 10. Selection of exon 10 generates the M2 type, which occurs in most tissues, whereas the M1 type is expressed by use of exon 9 only in skeletal muscle, heart and brain. We investigated the mechanism by which exon 10, but not exon 9 is selected in M2-expressing cells by transfecting minigenes containing exon 9 and/or exon 10 in cells and by analyzing the transcripts using reverse-transcriptase polymerase chain reaction. Deletion of the most conserved region in intron 8 did not affect selection of exon 10 in dRLh-84 cells, which express only the M2 type. Exclusion of exon 10 from the minigene resulted in two major spliced products. One included correctly spliced exon 9 and the other skipped this exon. Similar splicing patterns were observed when these minigenes were transfected in hepatocytes which express the L type, but not M1 or M2 types. The 5' splice site but not the 3' splice site of exon 9 was found to be hardly recognized by the splicing machinery in dRLh-84 cells. Mutation of the 5' splice site sequence of exon 9 to that of exon 10 and vice versa did not change the splicing patterns. However, mutation of this site of exon 9 to a perfectly complementary sequence of U1 snRNA resulted in selection of exon 9 correctly spliced to exon 10. A 9-10 fusion exon (constructed by substitution of 68 bases of the 3' portion of exon 9 and 33 bases of the 5' portion of intron 9 for the corresponding regions of exon 10 and intron 10) was also correctly incorporated into a major product together with exon 10. Thus, we propose that exon 9 is not recognized in non M1-expressing cells due to the weak signal of its 5' splice site and that, although the 5' splicing signal of exon 10 also appears to be weak, this exon can be recognized in these cells because the 5' recognition signal may be relatively strengthened by cis-acting element(s) which may be present in the 3' portion of exon 9 and the 5' portion of intron 9 and/or the corresponding regions of exon 10 and intron 10.