Parkinson Disease

Parkinson disease (PD) is one of the most common neurologic disorders, affecting approximately 1% of individuals older than 60 years and causing progressive disability that can be slowed, but not halted, by treatment. The 2 major neuropathologic findings in Parkinson disease are loss of pigmented dopaminergic neurons of the substantia nigra pars compacta and the presence of Lewy bodies and Lewy neurites.

Signs and symptoms

Initial clinical symptoms of Parkinson disease include the following:

• Tremor
  
• Subtle decrease in dexterity
  
• Decreased arm swing on the first-involved side
  
• Soft voice
  
• Decreased facial expression
  
• Sleep disturbances
  
• Rapid eye movement (REM) behavior disorder (RBD; a loss of normal atonia during REM sleep)
  
• Decreased sense of smell
  
• Symptoms of autonomic dysfunction (eg, constipation, sweating abnormalities, sexual dysfunction, seborrheic dermatitis)
  
• A general feeling of weakness, malaise, or lassitude
  
• Depression or anhedonia
  
• Slowness in thinkin

Onset of motor signs include the following:

• Typically asymmetric
  
• The most common initial finding is a resting tremor in an upper extremity
  
• Over time, patients experience progressive bradykinesia, rigidity, and gait difficulty
  
• Axial posture becomes progressively flexed and strides become shorter
  
• Postural instability (balance impairment) is a late phenomenon

Nonmotor symptoms

Nonmotor symptoms are common in early Parkinson disease. Recognition of the combination of nonmotor and motor symptoms can promote early diagnosis and thus early intervention, which often results in a better quality of life.

Diagnosis

Parkinson disease is a clinical diagnosis. No laboratory biomarkers exist for the condition, and findings on routine magnetic resonance imaging and computed tomography scans are unremarkable.

Clinical diagnosis requires the presence of 2 of 3 cardinal signs:

• Resting tremor
  
• Rigidity
  
• Bradykinesia
  

Management

The goal of medical management of Parkinson disease is to provide control of signs and symptoms for as long as possible while minimizing adverse effects.

Symptomatic drug therapy

• Usually provides good control of motor signs of Parkinson disease for 4-6 years
  
• Levodopa/carbidopa: The gold standard of symptomatic treatment
  
• Monoamine oxidase (MAO)–B inhibitors: Can be considered for initial treatment of early disease
  
• Other dopamine agonists (eg, ropinirole, pramipexole): Monotherapy in early disease and adjunctive therapy in moderate to advanced disease
  
• Anticholinergic agents (eg, trihexyphenidyl, benztropine): Second-line drugs for tremor only
  

Treatment for nonmotor symptoms

• Sildenafil citrate (Viagra): For erectile dysfunction
  
• Polyethylene glycol: For constipation
  
• Modafinil: For excessive daytime somnolence
  
• Methylphenidate: For fatigue (potential for abuse and addiction)
  

Deep brain stimulation

• Surgical procedure of choice for Parkinson disease
  
• Does not involve destruction of brain tissue
  
• Reversible
  
• Can be adjusted as the disease progresses or adverse events occur
  
• Bilateral procedures can be performed without a significant increase in adverse events
  

Prognosis

Before the introduction of levodopa, Parkinson disease caused severe disability or death in 25% of patients within 5 years of onset, 65% within 10 years, and 89% within 15 years. The mortality rate from Parkinson disease was 3 times that of the general population matched for age, sex, and racial origin. With the introduction of levodopa, the mortality rate dropped approximately 50%, and longevity was extended by many years. This is thought to be due to the symptomatic effects of levodopa, as no clear evidence suggests that levodopa stems the progressive nature of the disease.

The American Academy of Neurology notes that the following clinical features may help predict the rate of progression of Parkinson disease :
Older age at onset and initial rigidity/hypokinesia can be used to predict (1) a more rapid rate of motor progression in those with newly diagnosed Parkinson disease and (2) earlier development of cognitive decline and dementia; however, initially presenting with tremor may predict a more benign disease course and longer therapeutic benefit from levodopa
A faster rate of motor progression may also be predicted if the patient is male, has associated comorbidities, and has postural instability/gait difficulty (PIGD)
Older age at onset, dementia, and decreased responsiveness to dopaminergic therapy may predict earlier nursing home placement and decreased survival
Patient Education

Patients with Parkinson disease should be encouraged to participate in decision making regarding their condition. In addition, individuals and their caregivers should be provided with information that is appropriate for their disease state and expected or ongoing challenges. Psychosocial support and concerns should be addressed and/or referred to a social worker or psychologist as needed.

Prevention of falls should be discussed. The UK National Institute for Health and Clinical Excellence has several guidance documents including those for patients and caregivers.

Other issues that commonly need to be addressed at appropriate times in the disease course include cognitive decline, personality changes, depression, dysphagia, sleepiness and fatigue, and impulse control disorders. Additional information is also often needed for financial planning, insurance issues, disability application, and placement (assisted living facility, nursing home).

Intermittent fasting may change how your DNA is expressed

Mice who only ate at specific times of the day experienced “profound” changes in genetic expression, leading to health benefits like reduced risk of obesity and inflammation, new research found.

To an extent, it’s not about  what you eat as much as when you eat it — so says recent research that sheds new light on the benefits of intermittent fasting. 

The study, published Tuesday in journal Cell Metabolism, found that mice fed only during certain blocks of time experienced “profound” changes in gene expression. Nearly 80 per cent of all genes were impacted in some way, the paper reads.

The changes resulted in a plethora of health benefits, the authors wrote, including: improved blood sugar regulation, decreased risk of obesity and even a reversal of certain hallmarks of ageing.
You can think of a gene as the blueprint for a specific protein, written in DNA. When a gene is expressed, the blueprint is converted into its protein product by cellular machinery. Because proteins are responsible for most cellular functions from fat metabolism to immune response, even slight changes in gene expression could leave a massive impact.

According to the research, restricting when mice could eat reshaped when and to what extent certain genes were expressed — for example, some organs learned to switch on the genes for regulating blood sugar when it came feeding time, and to repress them when it was time to fast.

The researchers say their findings opened the door for further research into how dietary interventions might impact our genes and what this means for those suffering from issues like diabetes, heart disease and cancer.

What is time-restricted eating?

Shaunak Deota, first author of the study and a post-doctoral fellow at the Salk Institute for Biological Studies in San Diego, explained time-restricted eating as “eating consistently in a narrow window of 8 to 10 hours” when one is most active and fasting the remainder of the day. Intermittent fasting is a form of this practice, he said.

By feeding and fasting at the same time every day, we are reinforcing a biological rhythm in our bodies, Deota said: “Our body is getting the food at the same time every day, so all our organ systems know when the food is going to come and they’re prepared for it.”

Previous studies have shown that time-restricted eating may reduce the risk of obesity and diabetes, help to improve cardiovascular health, provide benefits for gut function and cardiovascular health and more.

Deota’s research now contributes, to his knowledge, the first “holistic” look at how time-restricted eating impacts the body as a system.

To achieve their results, the researchers put two groups of mice on the same high-calorie diet. One group was only allowed to eat during a nine-hour window when they were most active. The other could feed whenever they wanted.

After seven weeks, the mice on a time-restricted diet gained less weight than their counterparts, despite eating the same amount of food. 

The researchers then killed 48 of the mice — 24 from each group — to investigate the diet’s impact on the body. They sacrificed two mice from each group every two hours over a 24-hour period, noting how their organ systems changed over time.

How time-restricted eating changes the body

After studying the mouse organs, Deota and his team made a “pretty surprising” discovery; mice on the time-restricted diet had synchronized their gene expression with their feeding schedules.

“That is important because these genes will get translated into proteins,” Deota said. “Those proteins are helping our body to anticipate that there is food coming.”

According to their paper, roughly 70 per cent of all mouse genes fell into rhythm with the feeding schedule. Come mealtime, individual organs could promote genes in charge of nutrient metabolism while suppressing those responsible for inflammatory signalling and immune activation.

Moreover, the scientists found the diet reversed several hallmarks of aging, leading to reduced inflammation, increased cellular housekeeping, improved RNA and protein balance and more.

“Molecularly speaking, we saw a lot of pathways which are activated by (the time-restricted diet) in multiple organ systems. And a lot of these pathways actually have been implicated in improving health and leading to a longer, healthy life,” Deota said.

The limitations

All that being said, we need to remember these results were seen in mice, not humans — we’re still a long way off from demonstrating the same phenomenon happens in people, said Dani Renouf, a registered dietitian at St. Paul’s Hospital in Vancouver. For now, these results represent a “wonderful start to a conversation.”

“We’re just prototyping at this point because we’re using animal models and looking at things on a cellular level,” she said. “In order to now make conclusions in human beings, we need to take several steps before we can definitively do that with time restricted-eating.”

Renouf also noted the experiments took place in a tightly controlled environment. Real life is messy and chaotic, she said, and will likely influence results.

On the flip side, Deota believes “most of these benefits can be translated to humans” because his lab’s findings line up with what clinical studies into time-restricted eating have discovered.

CHINESE COVID-19 VACCINE EFFECTIVE IN MONKEYS

Researchers at Beijing pharmaceutical company Sinovac Biotech have developed an experimental COVID-19 vaccine that it says protected macaques from infection, ScienceMagazine reports.

The vaccine was based on a tried-and-true formulation that included an inactivated version of the virus SARS-CoV-2, as detailed in a preprint uploaded to the server bioRxiv on April 19.

“These data support the rapid clinical development of SARS-CoV-2 vaccines for humans,” reads the paper.

The team at Sinovac injected eight macaque monkeys with two different doses. Three weeks after injection, they introduced the coronavirus straight into the money’s lungs. There were reportedly no side effects.

None of the monkeys developed an infection beyond a small “viral blip.” A less fortunate control group of monkeys developed severe pneumonia after being infected by the virus.

“This is old school but it might work,” Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai, who co-authored a status report on COVID vaccine candidates, told Science Mag. “What I like most is that many vaccine producers, also in lower–middle-income countries, could make such a vaccine.”

Critics say, though, that the sample size in Sinovac’s trial was too small to produce generalizable results. Questions also remain about the viability of the vaccine candidate for use in humans — especially considering that monkeys don’t experience the same severe symptoms of COVID as humans.

In a separate Sinovac experiment, the researchers mixed a cocktail of antibodies from patients in China, Italy, Switzerland, Spain, and the United Kingdom with the virus.

According to the team, the antibodies “potently neutralized 10 representative SARS-CoV-2 strains, indicative of a possible broader neutralizing ability.”

And that’d be good news.

“This provides strong evidence that the virus is not mutating in a way that would make it resistant to a #COVID19 vaccine,” tweeted of Oregon Health & Science University immunologist Mark Slifka on Wednesday.

Sinovac Biotech is now planning trials on thousands of human subjects.

SCIENTISTS CREATE ARTIFICIAL GENOME THAT CAN REPRODUCE

German scientists say that for the first time ever, they’ve created a lab-grown artificial genome that can reproduce itself like a natural one.

It’s not quite one of those replicants from “Blade Runner,” but it’s a step toward the holy grail of synthetic biology: fully artificial organisms that can survive and reproduce like the real thing.
In a paper published in the journal Nature Communications this week, researchers from the Max Planck Institute of Biochemistry describe how they assembled genomes made up of blueprints for proteins — and demonstrated that it was capable of replicating 116 kilobytes worth of its own RNA and DNA.

Next up, according to a press release, the team plans to build an “enveloped system” that can reproduce like this last one — but also consume nutrition and dispose of waste, like a living cell.

READ MORE: Reproductive genome from the laboratory [Max Planck Society]

SCIENTISTS DISCOVER IMMUNE CELL THAT KILLS MOST CANCERS

A newly discovered immune cell could lead to the creation of a universal oncology treatment — a system that would work for all cancers, in all people.

The treatment leverages T-cells, a type of white blood cell that helps our bodies’ immune systems by scanning for and killing abnormal cells. For background, scientists have recently started harnessing that ability in the fight against cancer through CAR-T, which involves removing T-cells from a patient’s blood and genetically engineering them to seek out and destroy cancer cells.

While promising, CAR-T has limitations. It’s patient-specific, works against only a small number of cancers, and isn’t effective against solid tumors, which comprise the majority of cancers.

On Monday, researchers from Cardiff University published a new study in the journal Nature Immunology detailing their discovery of a T-Cell equipped with a new type of T-cell receptor (TCR) that recognizes a molecule called MR1.

This molecule appears on the surface of many types of cancer cells as well as healthy cells, but T-cells equipped with this TCR know to kill only cancer cells.

And not just the kind linked to a single type of cancer, either. When the Cardiff researchers equipped T-cells in lab tests with this new TCR, the cells killed lung, skin, blood, colon, breast, bone, prostate, ovarian, kidney and cervical cancer cells — all while ignoring healthy cells.

In another lab test, the team modified the T-cells of melanoma patients to express the newly discovered TCR and found that the cells could then target and destroy both that patient’s own cancer cells and the cancer cells of other patients.

The team has yet to test the modified T-cells in actual cancer patients, but when tested in mice injected with human cancers, the cells recognized the MR1 molecule and exhibited “encouraging” cancer-killing abilities, according to a Cardiff press release.

The Cardiff scientists now plan to conduct additional tests. If those goes as hoped, the treatment could be ready for patients within a few years, researcher Andrew Sewell said in the press release.

“Cancer-targeting via MR1-restricted T-cells is an exciting new frontier,” he added. “It raises the prospect of a ‘one-size-fits-all’ cancer treatment; a single type of T-cell that could be capable of destroying many different types of cancers across the population. Previously nobody believed this could be possible.”

Scientists have finally decoded the bizarre behaviors of brain cells — and recreated them in tiny computer chips.

The tiny neurons could change the way we build medical devices because they replicate healthy biological activity but require only a billionth of the energy needed by microprocessors, according to a University of Bath press release.

Neurons behave similar to electrical circuits within the body, but their behavior is less predictable — especially when it comes to parsing the relationship between their input and output electrical impulses. But these new artificial brain cells successfully mimic the behavior of rat neurons from two specific regions of the brain, according to research published Tuesday in Nature Communications.

“Until now neurons have been like black boxes, but we have managed to open the black box and peer inside,” University of Bath physicist Alain Nogaret said in the release. “Our work is paradigm changing because it provides a robust method to reproduce the electrical properties of real neurons in minute detail.”

The ultimate goal is to use these neurons to build medical devices that can better cater to patients’ needs, like a smarter pacemaker that can respond to new stressors and demands on a person’s heart — essentially upgrading devices to be more in tune with the body.

Julian Paton, a physiologist at the universities of Auckland and Bristol, said in the release that recreating biological activity was exciting because it “opens up enormous opportunities for smarter medical devices that drive towards personalized medicine approaches to a range of diseases and disabilities.”

Bad Manager mistakes that make good people quite... !

It’s pretty incredible how often you hear managers complaining about their best employees leaving, and they really do have something to complain about—few things are as costly and disruptive as good people walking out the door.

Managers tend to blame their turnover problems on everything under the sun, while ignoring the crux of the matter: people don’t leave jobs; they leave managers.

The sad thing is that this can easily be avoided. All that’s required is a new perspective and some extra effort on the manager’s part.

Organizations know how important it is to have motivated, engaged employees, but most fail to hold managers accountable for making it happen.

When they don’t, the bottom line suffers.

Research from the University of California found that motivated employees were 31% more productive, had 37% higher sales, and were three times more creative than demotivated employees. They were also 87% less likely to quit, according to a Corporate Leadership Council study on over 50,000 people.

Gallup research shows that a mind-boggling 70% of an employee’s motivation is influenced by his or her manager. So, let's take a look at some of the worst things that managers do that send good people packing.

They overwork people. Nothing burns good employees out quite like overworking them. It’s so tempting to work your best people hard that managers frequently fall into this trap. Overworking good employees is perplexing; it makes them feel as if they’re being punished for great performance. Overworking employees is also counterproductive. New research from Stanford shows that productivity per hour declines sharply when the workweek exceeds 50 hours, and productivity drops off so much after 55 hours that you don’t get anything out of working more.

If you must increase how much work your talented employees are doing, you’d better increase their status as well. Talented employees will take on a bigger workload, but they won’t stay if their job suffocates them in the process. Raises, promotions, and title-changes are all acceptable ways to increase workload. If you simply increase workload because people are talented, without changing a thing, they will seek another job that gives them what they deserve.

They don’t recognize contributions and reward good work. It’s easy to underestimate the power of a pat on the back, especially with top performers who are intrinsically motivated. Everyone likes kudos, none more so than those who work hard and give their all. Managers need to communicate with their people to find out what makes them feel good (for some, it’s a raise; for others, it’s public recognition) and then to reward them for a job well done. With top performers, this will happen often if you’re doing it right.

They fail to develop people’s skills. When managers are asked about their inattention to employees, they try to excuse themselves, using words such as “trust,” “autonomy,” and “empowerment.” This is complete nonsense. Good managers manage, no matter how talented the employee. They pay attention and are constantly listening and giving feedback.

Management may have a beginning, but it certainly has no end. When you have a talented employee, it’s up to you to keep finding areas in which they can improve to expand their skill set. The most talented employees want feedback—more so than the less talented ones—and it’s your job to keep it coming. If you don’t, your best people will grow bored and complacent.

They don’t care about their employees. More than half of people who leave their jobs do so because of their relationship with their boss. Smart companies make certain their managers know how to balance being professional with being human. These are the bosses who celebrate an employee’s success, empathize with those going through hard times, and challenge people, even when it hurts. Bosses who fail to really care will always have high turnover rates. It’s impossible to work for someone eight-plus hours a day when they aren’t personally involved and don’t care about anything other than your production yield.

They don’t honor their commitments. Making promises to people places you on the fine line that lies between making them very happy and watching them walk out the door. When you uphold a commitment, you grow in the eyes of your employees because you prove yourself to be trustworthy and honorable (two very important qualities in a boss). But when you disregard your commitment, you come across as slimy, uncaring, and disrespectful. After all, if the boss doesn’t honor his or her commitments, why should everyone else?

They hire and promote the wrong people. Good, hard-working employees want to work with like-minded professionals. When managers don’t do the hard work of hiring good people, it’s a major demotivator for those stuck working alongside them. Promoting the wrong people is even worse. When you work your tail off only to get passed over for a promotion that’s given to someone who glad-handed their way to the top­­­­­­­, it’s a massive insult. No wonder it makes good people leave.

They don't let people pursue their passions. Talented employees are passionate. Providing opportunities for them to pursue their passions improves their productivity and job satisfaction. But many managers want people to work within a little box. These managers fear that productivity will decline if they let people expand their focus and pursue their passions. This fear is unfounded. Studies show that people who are able to pursue their passions at work experience flow, a euphoric state of mind that is five times more productive than the norm.

They fail to engage creativity. The most talented employees seek to improve everything they touch. If you take away their ability to change and improve things because you’re only comfortable with the status quo, this makes them hate their jobs. Caging up this innate desire to create not only limits them, it limits you.

They don't challenge people intellectually. Great bosses challenge their employees to accomplish things that seem inconceivable at first. Instead of setting mundane, incremental goals, they set lofty goals that push people out of their comfort zones. Then, good managers do everything in their power to help them succeed. When talented and intelligent people find themselves doing things that are too easy or boring, they seek other jobs that will challenge their intellects.

Bringing It All Together

If you want your best people to stay, you need to think carefully about how you treat them. While good employees are as tough as nails, their talent gives them an abundance of options. You need to make them want to work for you.

What other mistakes cause great employees to leave? Please share your thoughts in the comments section below as I learn just as much from you as you do from me.

Scientists Hope to Use Stem Cells to Reverse Death in Controversial Study

Researchers seem to be setting their sights on increasingly lofty goals when it comes to the human body – from the world’s first human head transplant, to fighting ageing, and now reversing death altogether. Yes, you read that right. A company called Bioquark hopes to bring people who have been declared clinically brain-dead back to life. The Philadelphia-based biotech company is expected to start on the project later this year.

This trial was originally intended to go forward in 2016 in India, but regulators shut it down. Assuming this plan will be substantially similar, it will enroll 20 patients who will undergo various treatments. The stem cell injection will come first, with the stem cells isolated from that patient’s own blood or fat. Next, the protein blend gets injected directly into the spinal cord, which is intended to foster growth of new neurons. The laser therapy and nerve stimulation follow for 15 days, with the aim of prompting the neurons to make connections. Meanwhile, the researchers will monitor both behavior and EEGs for any signs of the treatment causing any changes.

BACK FROM THE DEAD

Researchers seem to be setting their sights on increasingly lofty goals when it comes to the human body – from the world’s first human head transplant, to fighting aging, and now reversing death altogether. Yes, you read that right. A company called Bioquark hopes to bring people who have been declared clinically brain-dead back to life. The Philadelphia-based biotech company is expected to start on the project later this year.

This trial was originally intended to go forward in 2016 in India, but regulators shut it down. Assuming this plan will be substantially similar, it will enroll 20 patients who will undergo various treatments. The stem cell injection will come first, with the stem cells isolated from that patient’s own blood or fat. Next, the protein blend gets injected directly into the spinal cord, which is intended to foster growth of new neurons. The laser therapy and nerve stimulation follow for 15 days, with the aim of prompting the neurons to make connections. Meanwhile, the researchers will monitor both behavior and EEGs for any signs of the treatment causing any changes.

CONTROVERSIAL IDEAS

While there is some basis in science for each step in the process, the entire regimen is under major scrutiny. The electrical stimulation of the median nerve has been tested, but most evidence exists in the form of case studies. Dr. Ed Cooper has described dozens of these cases, and indicates that the technique can have some limited success in some patients in comas. However, comas and brain death are very different, and Bioquark’s process raises more questions for most researchers than it answers.

One issue researchers are raising about this study is informed consent. How can participants in the trial consent, and how should researchers complete their trial paperwork – given that the participants are legally dead —and how can brain death be conclusively confirmed, anyway? What would happen if any brain activity did return, and what would the patient’s mental state be? Could anything beyond extreme brain damage even be possible?

As reported by Stat News, In 2016, neurologist Dr. Ariane Lewis and bioethicist Arthur Caplan wrote in Critical Care that the trial is “dubious,” “has no scientific foundation,” and suffers from an “at best, ethically questionable, and at worst, outright unethical nature.” According to Stat News, despite his earlier work with electrical stimulation of the median nerve, Dr. Cooper also doubts Bioquark’s method, and feels “there is no way this technique could work on someone who is brain-dead. The technique, he said, relies on there being a functional brain stem — one of the structures that most motor neurons go through before connecting with the cortex proper. If there’s no functional brain stem, then it can’t work.”

Peadiatric surgeon Charles Cox, who is not involved in Bioquark’s work, agrees with Cooper, commenting to Stat News on Bioquark’s full protocol, “it’s not the absolute craziest thing I’ve ever heard, but I think the probability of that working is next to zero. I think [someone reviving] would technically be a miracle.”

Pastor remains optimistic about Bioquark’s protocol. “I give us a pretty good chance,” he said. “I just think it’s a matter of putting it all together and getting the right people and the right minds on it.”

References: Scientific American, Science, Stat News, Critical Care

New Research Shows That Chronic Fatigue Syndrome Isn’t Just “All in Your Head”

Researchers have discovered that people with chronic fatigue syndrome/myalgic encephalomyelitis have elevated levels of seven specific species of gut bacteria. This discovery could lead to targeted diagnostic tools and treatments for the disease.

CHRONIC FATIGUE SYNDROME

Chronic fatigue syndrome/myalgic encephalomyelitis (ME/CFS) is a debilitating disorder. The fatigue and other symptoms it causes result in an inability to participate in the daily activities of life for many sufferers. Although more than one million Americans have ME/CFS — more than lupus, multiple sclerosis, and some types of cancer — there is not yet any treatment, or meaningful diagnostic tool. Four times as many women suffer from ME/CFS, and it lasts for years in some patients.

Although the disease was previously thought of as some kind of imaginary ailment, ME/CFS is now being taken seriously by researchers. This week, new research published in Microbiome reveals that people who have ME/CFS also have abnormal levels of specific gut bacteria — and the levels of bacteria vary with symptom severity.

“By identifying the specific bacteria involved, we are one step closer to more accurate diagnosis and targeted therapies,” head researcher Ian Lipkin said in a press release from the Center for Infection and Immunity (CII) and the Mailman School of Public Health of Columbia University.

The team carefully matched, and then followed, 50 ME/CFS patients and 50 healthy controls. They took fecal and blood samples from all participants, and tested the fecal samples for bacterial species and the blood for immune molecules. Seven distinct species of intestinal bacteria were so strongly associated with ME/CFS that an accurate diagnosis could be predicted based on the elevated presence of all of them.

Although this study included a small sample, subject to further verification, this research could be the first step toward targeted diagnostic tools and treatments for the disease.

References: ScienceAlert - Latest, Microbiome Journal, Columbia University Mailman School of Public Health, CDC