Erythropoietin as a Retinal Angiogenic Factor in Proliferative Diabetic Retinopathy

Although vascular endothelial growth factor (VEGF) is a primary mediator of retinal angiogenesis, VEGF inhibition alone is insufficient to prevent retinal neovascularization. Hence, it is postulated that there are other potent ischemia-induced angiogenic factors. Erythropoietin possesses angiogenic activity, but its potential role in ocular angiogenesis is not established.

METHODS

We measured both erythropoietin and VEGF levels in the vitreous fluid of 144 patients with the use of radioimmunoassay and enzyme-linked immunosorbent assay. Vitreous proliferative potential was measured according to the growth of retinal endothelial cells in vitro and with soluble erythropoietin receptor. In addition, a murine model of ischemia-induced retinal neovascularization was used to evaluate erythropoietin expression and regulation in vivo.

RESULTS

The median vitreous erythropoietin level in 73 patients with proliferative diabetic retinopathy was significantly higher than that in 71 patients without diabetes (464.0 vs. 36.5 mIU per milliliter, P<0.001). The median VEGF level in patients with retinopathy was also significantly higher than that in patients without diabetes (345.0 vs. 3.9 pg per milliliter, P<0.001). Multivariate logistic-regression analyses indicated that erythropoietin and VEGF were independently associated with proliferative diabetic retinopathy and that erythropoietin was more strongly associated with the presence of proliferative diabetic retinopathy than was VEGF. Erythropoietin and VEGF gene-expression levels are up-regulated in the murine ischemic retina, and the blockade of erythropoietin inhibits retinal neovascularization in vivo and endothelial-cell proliferation in the vitreous of patients with diabetic retinopathy in vitro.

CONCLUSIONS

Our data suggest that erythropoietin is a potent ischemia-induced angiogenic factor that acts independently of VEGF during retinal angiogenesis in proliferative diabetic retinopathy.

Article:-

Pathologic growth of new blood vessels is a common final pathway in ocular neovascular diseases, such as proliferative diabetic retinopathy, that often result in catastrophic loss of vision. Vascular endothelial growth factor (VEGF) is a primary angiogenic factor that mediates such ischemia-induced retinal neovascularization. VEGF levels are elevated in the vitreous fluid of patients with proliferative diabetic retinopathy, and VEGF induces proliferation in vascular endothelial cells in vitro.¹ Although inhibition of VEGF reduces retinal neovascularization,^2,3 it does not completely inhibit ischemia-driven retinal neovascularization. Thus, the involvement of other angiogenic factors in this process seems likely.

The glycoprotein erythropoietin stimulates the formation of red cells by enhancing both their proliferation and their differentiation and by preventing apoptotic death of erythropoietin-responsive erythroid precursor cells.^4-6 A major signal that regulates the production of erythropoietin in these tissues is hypoxia, and the brain has a paracrine system involving erythropoietin and erythropoietin receptors, suggesting that erythropoietin contributes to the survival of neurons by protecting them from ischemic damage.^7-9 Furthermore, erythropoietin shows angiogenic activity in vascular endothelial cells, stimulating proliferation, migration, and angiogenesis in vitro, probably by means of the erythropoietin receptor expressed in those cells.^10,11 Such angiogenic activity involves several signal-transduction cascades such as extracellular signal-regulated kinase, Janus kinase 2 (known as JAK2), and signal transducer and activator of transcription 5 (STAT5).^12-15 Moreover, the inhibition of erythropoietin by soluble erythropoietin receptor abrogates angiogenesis in vivo.^16,17

Since erythropoietin is an ischemia-induced paracrine factor that promotes angiogenesis, we wished to identify its potential role during retinal angiogenesis in proliferative diabetic retinopathy. Therefore, we examined in vitro the expression and function of erythropoietin in the vitreous fluid of patients with proliferative diabetic retinopathy and evaluated the role of erythropoietin in an in vivo experimental model of retinal angiogenesis. Our data provide strong evidence that erythropoietin is a potent retinal angiogenic factor independent of VEGF and is capable of stimulating ischemia-induced retinal angiogenesis in proliferative diabetic retinopathy.

Daisuke Watanabe, M.D., Ph.D., Kiyoshi Suzuma, M.D., Ph.D., Shigeyuki Matsui, Ph.D., Masafumi Kurimoto, M.D., Junichi Kiryu, M.D., Ph.D., Mihori Kita, M.D., Ph.D., Izumi Suzuma, M.D., Ph.D., Hirokazu Ohashi, M.D., Ph.D., Tomonari Ojima, M.D., Tomoaki Murakami, M.D., Toshihiro Kobayashi, Ph.D., Seiji Masuda, Ph.D., Masaya Nagao, Ph.D., Nagahisa Yoshimura, M.D., Ph.D., and Hitoshi Takagi, M.D., Ph.D.

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August 25, 2005

N Engl J Med 2005; 353:782-792

www.nejm.com

New Aspirin Guide Mobile app helping clinicians and patients... both

New Aspirin-Guide mobile app helps clinicians and patients make informed decisions about aspirin use

Posted in: Device / Technology News | Medical Research News | Medical Condition News | Pharmaceutical News

Published on June 21, 2016 at 12:15 PM

Low dose aspirin is recommended by clinicians as a preventive measure for patients who have already had a heart attack or stroke, but the risk of taking low-dose aspirin to prevent or delay a first heart attack or stroke is less clear, as the benefit for reducing the risk of cardiovascular disease (CVD) must be balanced with the increased risk of gastrointestinal or other bleeding. To help clinicians and patients make informed decisions about aspirin use, researchers at Brigham and Women's Hospital have developed a new, free, mobile app, "Aspirin-Guide" that calculates both the CVD risk score and the bleeding risk score for the individual patient, and helps clinicians decide which patients are appropriate candidates for the use of low-dose aspirin (75 to 81 mg daily).

"We developed the Aspirin-Guide app because we realized that weighing the risks and benefits of aspirin for individuals who have not had a heart attack or stroke is a complex process. The new mobile app enables individualized benefit to risk assessment in a matter of seconds while the patient is with the physician," said Samia Mora, MD, cardiologist at BWH.

In a commentary published in JAMA in the June 20 issue, and a review in JAMA Internal Medicine published on the same day, co-authors Mora, and JoAnn Manson, MD, cardiovascular epidemiologist and Chief of Preventive Medicine at BWH, review the evidence behind the use of aspirin to delay or prevent a first heart attack of stroke, and give examples of how the mobile app can help patients and clinicians including:

•calculates a 10-year cardiovascular disease risk score (heart disease and stroke) for the patient
•calculates a bleeding risk score based on the patient's individual risk factors
•uses evidence from the literature, together with the above scores, to compare the number needed to treat vs. the number needed to harm
•helps clinicians to implement current clinical guidelines for low-dose aspirin in primary prevention
•provides the ability to email a summary of the decision-making process to the patient and/or to the clinician for the patient's record.

"Aspirin-Guide is a user-friendly clinical decision support tool, that will facilitate informed and personalized decision-making about the use of aspirin in primary prevention of CVD. Patients should discuss the pros and cons of aspirin treatment with their healthcare provider," Manson said.

Source: Brigham and Women’s Hospital

Penicillin redux: Rearming proven warriors for the 21st century

Penicillin, one of the scientific marvels of the 20^th century, is currently losing a lot of battles it once won against bacterial infections. But scientists at the University of South Carolina have just reported a new approach to restoring its combat effectiveness, even against so-called "superbugs."

Bacteria have been chipping away at the power of the penicillin family of drugs since their first wide-scale use as antibiotics in the 1940s. For example, the staph infection, brought about by the bacterium Staphylococcus aureus, was once readily treated with penicillin and its molecular cousins.
But that bug has changed. In the 1960s, a new strain arrived, termed MRSA for methicillin- (or sometimes multidrug-) resistant S. aureus. It has become a serious public health problem because the earliest deployed antibiotics are often useless against the new strain, and its prevalence has only increased since it was first observed. MRSA (pronounced mer-suh) is sometimes called a superbug because of the difficulty physicians have in treating infected patients.
The S. aureus microbe has evolved the MRSA strain by developing a variety of defenses against antibiotics to which they've been exposed. One of those defenses effectively neutralizes penicillin's greatest strength.
That strength is its molecular core, a cyclic four-membered amide ring termed a beta-lactam. It is a common structural element of the penicillins, their synthetic and semi-synthetic derivatives, and other related molecules that constitute the broad family of drugs called the beta-lactam antibiotics. Just a few examples (of dozens) include amoxicillin, ampicillin and cefazolin.
The beta-lactam structure in a molecule is something that many bacteria don't like at all. It greatly hinders their ability to reproduce by cell division, and so chemists have for years spent time making molecules that all contain the beta-lactam structural motif, but differ in the surrounding molecular "shrubbery." Physicians heavily use the many versions of beta-lactam antibiotics to fight bacterial infections, and many have been retired because they're no longer effective against the defenses bacteria have evolved in response.
One of the most effective bacterial defenses is an enzyme called beta-lactamase, which chews up the beta-lactam structure. Some bacteria, such as MRSA, have developed the ability to biosynthesize and release beta-lactamase when needed. It's a devastating defense because it's so general, targeting the common structural motif in all of the many beta-lactam antibiotics.
But that also creates the opportunity for a general approach to solving the problem, which is what Carolina's Chuanbing Tang and colleagues just reported in the Journal of the American Chemical Society.
"Instead of developing new antibiotics, here we ask the question, 'can we recycle the old antibiotics?' " he said. "With traditional antibiotics like penicillin G, amoxicillin, ampicillin and so on, can we give them new life?"
The approach pairs the drug with a protective polymer developed in Tang's chemistry laboratory. In lab tests, graduate student Jiuyang Zhang prepared a cobaltocenium metallopolymer that greatly slowed the destructiveness of beta-lactamase on a model beta-lactam molecule (nitrocefin).
The interdisciplinary team, which included Mitzi Nagarkatti and Alan Decho, from the university's School of Medicine and Arnold School of Public Health, respectively, also showed that the antimicrobial effectiveness of the four beta-lactams studied in detail was enhanced by the polymer. The enhancement was modest against two strains, but very pronounced with the hospital-associated strain of MRSA (HA-MRSA).
The metallopolymer by itself even demonstrated antimicrobial properties, lysing bacterial cells while leaving human red blood cells unaffected. By a variety of measures, the polymer was found to be nontoxic to human cells in laboratory tests.
The project is still far from clinical use, but Tang knows moving forward is imperative.
"In the United States every year, around 100,000 patients die of bacteria-induced infections," Tang said. "And the problem is increasing because bacteria are building resistance. It's a really, really big problem, not only for individual patients, but also for society."

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Story Source:
The above story is based on materials provided by University of South Carolina. The original article was written by Steven Powell. Note: Materials may be edited for content and length.

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Journal Reference:

1. Jiuyang Zhang, Yung Pin Chen, Kristen P. Miller, Mitra S. Ganewatta, Marpe Bam, Yi Yan, Mitzi Nagarkatti, Alan W. Decho, Chuanbing Tang. Antimicrobial Metallopolymers and Their Bioconjugates with Conventional Antibiotics against Multidrug-Resistant Bacteria. Journal of the American Chemical Society, 2014; 136 (13): 4873 DOI: 10.1021/ja5011338

Monoclonal Antibody Targets, Kills Leukemia Cells

Monoclonal Antibody Targets, Kills Leukemia Cells

 Researchers at the University of California, San Diego Moores Cancer Center have identified a humanized monoclonal antibody that targets and directly kills chronic lymphocytic leukemia (CLL) cells
The findings, published in the online Early Edition of the Proceedings of the National Academy of Sciences on March 25, 2013 represent a potential new therapy for treating at least some patients with CLL, the most common type of blood cancer in the United States.
CLL cells express high levels of a cell-surface glycoprotein receptor called CD44. Principal investigator Thomas Kipps, MD, PhD, Evelyn and Edwin Tasch Chair in Cancer Research, and colleagues identified a monoclonal antibody called RG7356 that specifically targeted CD44 and was directly toxic to cancer cells, but had little effect on normal B cells.
Moreover, they found RG7356 induced CLL cells that expressed the protein ZAP-70 to undergo apoptosis or programmed cell death. Roughly half of CLL patients have leukemia cells that express ZAP-70. Such patients typically have a more aggressive form of the disease than patients with CLL cells that do not express that specific protein.

Previous research by Kipps and others has shown that CLL cells routinely undergo spontaneous or drug-induced cell death when removed from the body and cultured in the laboratory. They found that CLL cells receive survival signals from surrounding non-tumor cells that are present in the lymph nodes and bone marrow of patients with CLL. One of these survival signals appears to be transmitted through CD44. However, when CD44 is bound by the RG7356 monoclonal antibody, it seems to instead convey a death signal to the leukemia cell.
"By targeting CD44, it may be possible to kill CLL cells regardless of whether there are sufficient numbers of so-called 'effector cells,' which ordinarily are required by other monoclonal antibodies to kill tumor cells," said Kipps. "We plan to initiate clinical trials using this humanized anti-CD44 monoclonal antibody in the not-too-distant future."
Co-authors were Suping Zhang, Christina C.N. Wu, Jessie-Farah Fecteau, Bing Cui, Liguang Chen, Ling Zhang, Rongrong Wu, Laura Rassenti, and Fitzgerald S. Lao, Department of Medicine, UCSD Moores Cancer Center; and Stefan Weigand, Roche Diagnostics GmbH, Germany.
Funding for this study came, in part, from the National Institutes of Health (grant PO1-CA081534) and the UC San Diego Moores Cancer Blood Center Research Fund.

Story Source:

The above story is reprinted from materials provided by University of California, San Diego Health Sciences.

Journal Reference:

1. Suping Zhang, Christina C. N. Wu, Jessie-F. Fecteau, Bing Cui, Liguang Chen, Ling Zhang, Rongrong Wu, Laura Rassenti, Fitzgerald Lao, Stefan Weigand, and Thomas J. Kipps. Targeting chronic lymphocytic leukemia cells with a humanized monoclonal antibody specific for CD44. PNAS, March 25, 2013 DOI: 10.1073/pnas.1221841110

Stem Cell Treatment May Become Option to Treat Nonhealing Bone Fractures

Stem Cell Treatment May Become Option to Treat Non healing Bone Fractures

Stem cell therapy enriched with a bone-regenerating hormone, insulin-like growth factor-I (IGF-I), can help mend broken bones in fractures that are not healing normally, a new animal study finds.
The results are being presented at The Endocrine Society's 93rd Annual Meeting in Boston.
A deficiency of fracture healing is a common problem affecting an estimated 600,000 people annually in North America, according to the principal investigator, Anna Spagnoli, MD, associate professor of pediatrics and biomedical engineering at the University of North Carolina at Chapel Hill.
"This problem is even more serious," Spagnoli said, "in children with osteogenesis imperfecta, or brittle bone disease, and in elderly adults with osteoporosis, because their fragile bones can easily and repeatedly break, and bone graft surgical treatment is often not successful or feasible"
Fractures that do not heal within the normal timeframe are called non-union fractures. Using an animal model of a non-union fracture, a "knockout" mouse that lacks the ability to heal broken bones, Spagnoli and her colleagues studied the effects of transplanting adult stem cells enriched with IGF-I. They took mesenchymal stem cells (adult stem cells from the bone marrow) of mice and engineered the cells to express IGF-1. Then they transplanted the treated cells into knockout mice with a fracture of the tibia, the long bone of the leg.
Using computed tomography (CT) scanning, the researchers showed that the treated mice had better fracture healing than did control mice either left untreated or treated only with stem cells. They found that the stem cells enriched with IGF-I became bone cells and helped the cells in the broken bones to repair the fracture, speeding the healing. Compared with controls left to heal on their own, treated mice had more bone bridging the fracture gap, and that new bone was three to four times stronger, according to Spagnoli.
"More excitingly, we found that stem cells empowered with IGF-I restored the formation of new bone in a mouse lacking the ability to repair broken bones. This is the first evidence that stem cell therapy can address a deficiency of fracture repair," she said.
This success in an animal model of fracture non-union, Spagnoli said, "is a crucial step toward developing a stem cell-based treatment for patients with fracture non-unions."
"We envision a clinical use of combined mesenchymal stem cells and IGF-1 similar to the approach employed in bone marrow transplant, in which stem cell therapy is combined with growth factors to restore blood cells," she said. "I think this treatment will be feasible to start testing in patients in a few years."
IGF-I is approved for treatment of children with a deficiency of this hormone, causing growth failure.
The National Institutes of Health supported this study through a NIDDK-NIH R01 grant.

STEM CELL THERAPY.....

Stem Cells Fill Gaps in Bones

 For many patients the removal of several centimetres of bone from the lower leg following a serious injury or a tumour extraction is only the beginning of a long-lasting ordeal. Autologous stem cells have been found to accelerate and boost the healing process. Surgeons at the RUB clinic Bergmannsheil have achieved promising results: without stem cells, it takes on average 49 days for one centimetre of bone to regrow; with stem cells, that period has been reduced to 37 days.
In the past, large bone defect inevitably led to an amputation. Today, the arm or leg is stabilised in an external support, and a transport wire is pulled through the marrow of the intact part of the injured bone. Once the soft tissue surrounding the injury is healed, the surgeons cut the healthy part of the bone into two. The transport wire is affixed to the winches of a ring fixator that is attached around the leg. Using a sophisticated cable-pull system, the previously detached part of the bone is slowly pulled either downwards or upwards along the gap in the bone until it arrives and docks at the other end. During the pulling stage, the periosteum of the bone that had been pulled apart had been continuously stretched. Thus, a periosteum tube is created in the gap behind the relocated portion of the bone. Inside that tube, the new bone can regenerate. This process, however, is extremely tedious and the treatment fails in every firth case.

Processing autologous stem cells in the operating theatre
Surgeons at the RUB clinic Bergmannsheil attempt to optimise the healing process by applying autologous stem cells therapy. Depending on the requirements, stem cells are capable of evolving into different types of tissue cells, including so-called osteoblasts -- cells that are responsible for bone formation. Adult stem cells such as are deployed in the process can be found in the bone marrow of adults. "We harvest them by inserting a hollow needle into the iliac crest," explains PD Dr Dominik Seybold, managing consultant at the clinic.
The stem cells are prepared for application directly on location. Under x-ray control, the surgeons inject six to eight millilitres of the concentrated fluid into the centre of the periosteum tube. X-ray controls are routinely performed to monitor the recovery progress. To date, the RUB physicians have applied this therapy in 20 cases. "This is not enough to be statistically relevant," admits Dr Seybold. Nevertheless, the researchers find the results very encouraging: whilst the bone regeneration process without stem cells used to take 49 days on average, it has been reduced to 37 days on average thanks to the new therapy method. So far, RUB scientists have been treating bone defects with an average length of eight centimetres -- consequently, the patients thus recovered, on average, three months sooner.

Story Source:

The above story is reprinted from materials provided by Ruhr-Universitaet-Bochum, via AlphaGalileo.