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MDLinx offers a broad spectrum of information on specific disease states, in a single, easy-to-navigate location, known as Resource Centers. Discover the latest news, research information, journal summaries, original content, educational tools and conference information.
Pneumococcal pneumonia is a common but serious infection and inflammation of the lungs. It is caused by the bacterium Streptococcus pneumoniae. The gram-positive, spherical bacteria, Streptococcus pneumoniae, is the cause of many human diseases, including pneumonia. It is estimated that about 900,000 Americans get pneumococcal pneumonia each year and about 5-7% die from it. As many as 400,000 hospitalizations from pneumococcal pneumonia are estimated to occur annually in the United States.
Pulmonary arterial hypertension is a distinct subgroup of pulmonary hypertension that comprises idiopathic PAH, familial/heritable forms, and PAH associated with connective tissue disease, congenital heart disease, portal hypertension, HIV infection, and other conditions. The hemodynamic definition of PAH was revised: PAH is now defined by a mean pulmonary artery pressure at rest > or =25 mm Hg in the presence of a pulmonary capillary wedge pressure < or =15 mm Hg.
Attention-deficit/hyperactivity disorder (ADHD) is marked by an ongoing pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development. Although symptoms begin in childhood, ADHD can continue through adolescence and adulthood. Even though hyperactivity tends to improve as a child becomes a teen, problems with inattention, disorganization, and poor impulse control can often continue. An estimated 5% of children and 2.5% of adults have ADHD.
Alzheimer’s disease is a neurodegenerative disease with pathologic features including neuritic plaques, extracellular amyloid deposits, neurofibrillary tangles, and accumulation of intracellular tau protein. Alzheimer’s disease is the most common cause of dementia, affecting 1 in 5 women and 1 in 10 men. Unlike early-onset disease, which exhibits an autosomal dominant pattern of inheritance, late-onset disease involves the APOE epsilon 4 gene, and epigenetic and environmental factors.
According to the CDC, the annual incidence of inpatient and outpatient infections attributed to antibiotic-resistant pathogens is 2 million, leading to 23,000 deaths. Although JCAH required all hospitals to have antibiotic stewardship programs effective 2017, <50% of hospitals are compliant. Approximately one-half of the 260 million antibiotic prescriptions dispensed to outpatients have been shown to be inappropriate and 30% of antibiotics prescribed to children are deemed unnecessary.
Asthma affects 10% of the US population. The increase in the incidence of asthma since the 1980s has been attributed to a robust immune response to otherwise innocuous allergens, such as dust and ragweed, but the underlying mechanism has not been fully elucidated. Asthma is characterized by airway hyperresponsiveness secondary to an inflammatory process driven by dysregulated T cells that secrete interleukins, which in turn recruit mast cells, eosinophils, basophils, macrophages, and B cells.
Benign prostatic hyperplasia (BPH) is a testosterone-, dihydrotesterone-, and estrogen-dependent proliferative disorder of epithelial cells and stroma that results in lower urinary tract complications, the most notable of which is urinary retention. BPH affects one-third of men by age 50 and 90% of men by age 85. While alcohol consumption and NSAID use may decrease the risk for BPH, an elevated PSA, heart disease, prostatitis, and use of beta-blockers are associated with an increased risk.
Binge eating disorder (BED) is characterized by altered reward sensitivity, reflecting alterations in dopaminergic and opioidergic neurotransmission. The lifetime prevalence of BED is 2%-3% and 2-fold higher in females than males. The average age of onset is 23 years and the disorder often persists >10 years. Approximately 80% of affected individuals have a co-morbid psychopathy, with specific phobias occurring in 40%, as well as chronic medical conditions.
Bipolar disorder is a neuroprogressive syndrome characterized by episodes of mania, major depression (the most common presenting symptom), hypomania, and impaired cognition. Affected individuals have a greater than 90% risk for a co-morbid psychiatric disorder, such as anxiety, substance abuse, and borderline personality disorder, and a 10%-15% probability for suicide. The lifetime prevalence for bipolar disorder is approximately 1%, with a mean age of onset between 18 and 20 years of age.
Bladder cancer (transitional cell carcinoma, squamous cell carcinoma, and adenocarcinoma) accounts for 80,000 new cases and 17,000 deaths in the US each year, respectively, and is the 4th most common cancer in males. Up to 80% of patients with bladder cancer have recurrent disease. While mutations in FGFR-3 (non–muscle-invasive) and TP53 (muscle-invasive) are known to play a role in the pathogenesis of bladder cancer, tobacco product and occupational exposure are the major etiologic factors.
Breast cancer is caused by development of malignant cells in the breast. The malignant cells originate in the lining of the milk glands or ducts of the breast, defining this malignancy as a cancer. About 1 in 8 US women (about 12%) will develop invasive breast cancer over the course of her lifetime. In 2017, an estimated 255,180 new cases of invasive breast cancer are expected to be diagnosed in women in the US, along with 63,410 new cases of non-invasive (in situ) breast cancer.
Chronic idiopathic constipation (CIC) is a condition in which a person experiences chronic symptoms of constipation, yet no obvious cause can be identified. CIC is also referred to as functional constipation, as CIC is classified as one of the functional gastrointestinal disorders, meaning that although testing does not show any visible physical abnormality, there is a problem in the way that the digestive system, or in this case, the large intestine, is functioning.
Major depressive disorder (MDD) is thought to represent a disturbance in the activity of neurotransmitters (most notably, serotonin) in neocortical and limbic structures. The estimated lifetime prevalence of MDD and dysthymia approaches 20%, with MDD affecting females more than males and the elderly more than the young. Up to 80% of those with depression respond to treatment; however, two-thirds of affected individuals are unaware of the significance of their symptoms and do not seek treatment.
Dry eye is a condition in which a person doesn't produce quality tears to lubricate and nourish the eye, according to the American Optometric Association. Tears are necessary for maintaining the health of the front surface of the eye and for providing clear vision. Dry eye is a common and often chronic problem, particularly in older adults. With each blink, tears spread across the front surface of the eye, or cornea. Dry eyes can occur when tear production and drainage is not in balance.
Human immunodeficiency virus (HIV) infection was first described in 1981. In 1996, the advent of antiretroviral therapy (ART) significantly reduced the morbidity and mortality associated with HIV infections. As a result, the global prevalence of HIV is on the rise, but the incidence of new infections is declining. To date, 70 million individuals have been infected with HIV, 50% of whom have died of HIV-related illnesses, and 36 million individuals are currently living with HIV.
Hematology Oncology is the diagnosis, treatment, and/or prevention of leukemias and lymphomas, iron deficiency anemia, hemophilia, sickle cell disease, and the thalassemias. In 2017, 62,000 cases of leukemia were diagnosed with 24,500 deaths occurring. Although the cause is unknown, risk factors include radiation and carcinogens. Approximately 80,000 cases of lymphoma were diagnosed in 2017, with 21,000 deaths. Risk factors include immunosuppression and infections such as Epstein-Barr and HCV.
Hepatitis C is caused by inflammation of the liver due to the hepatitis C virus (HCV), which is usually spread via blood transfusion, hemodialysis, and needle sticks. The damage hepatitis C does to the liver can lead to cirrhosis and its complications as well as cancer. Transmission of the virus by sexual contact is rare. At least half of hepatitis C patients develop chronic hepatitis C infection. Diagnosis is made by blood test.
Hepatology is the study of the liver and its diseases including, but not limited to, acute and chronic hepatitis, viral hepatitis, cirrhosis, genetic and metabolic liver diseases and their complications, liver cancer, liver transplantation, hemochromatosis, and drug metabolism and immunology (as related to the liver).
Hypertension affects one-third of adults (86 million) in the US. Despite the efficacy and safety of treatment, hypertension remains an undiagnosed and undertreated disease. Although the precise pathophysiologic mechanism leading to hypertension has not been established, recent evidence suggests a significant role for aberrant T cell activation by isoketals and isolevuglandins, and cytokine secretion (IL-17 and TNF-α), which together lead to elevated blood pressure and organ damage.
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is characterized by small bowel and colonic dysmotility, visceral hyperalgesia, and psychopathy. The population prevalence of IBS is between 10% and 15% (females, 14%; males, 9%), and the annual incidence is 1% to 2%. Nearly one-half of individuals who satisfy the diagnostic criteria for IBS are not diagnosed. Over time, symptoms remit in up to 40% of patients; however, IBS progresses in nearly 20% of patients.
According to the NIDDK, approximately 661,000 people in the US have end-stage renal disease and 468,000 currently receive dialysis treatment; 94% of patients are on hemodialysis and 6% are on peritoneal dialysis. Hemodialysis costs nearly $90,000 per patient per year ($42 billion/year total); thus, 7% of the Medicare budget is allotted to treatment of the 1% of Medicare patients who require dialysis. Although gradually improving, the 60-month probability of survival is <0.40.
Lung cancer, also known as lung carcinoma, is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung by the process of metastasis into nearby tissue or other parts of the body. Most cancers that start in the lung, known as primary lung cancers, are carcinomas. The two main types are small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC).
A melanoma is a malignancy involving melanocytes, with 4 major subtypes and 4 variants. Although f genes have been implicated in the development of melanomas, most notably p16, exposure to ultraviolet radiation is essential. Melanomas represent approximately 1% of all skin cancers, but account for most skin cancer-related deaths. According to the American Cancer Society, the prevalence of melanoma is >90,000 per year, thus making melanoma the sixth most common cancer, with >9,000 deaths.
About 80% of mesotheliomas affect the pleura, 70% of which are associated with exposure to asbestos. The peritoneum, pericardium, and tunica vaginalis are rarely involved. According to the CDC, of the 8 million US residents who have been exposed to asbestos, there are approximately 3,300 new cases of malignant mesothelioma diagnosed each year and 2,500 deaths. The lifetime risk of malignant mesothelioma among asbestos workers approaches 10% with a reported latency period up to 40 years.
Migraine is a neurogenic process with alterations in cerebral perfusion characterized by four phases—prodrome, aura, headache, and postdrome—and can involve a variety of sensory disturbances followed by a severe headache, often on one side of the head. Migraine affects approximately 12% of the population (18% and 6% of women and men, respectively) and tends to affect people aged 15 to 55 years. Current treatment involves acute and prophylactic medications, as well as avoidance of triggers.
Multiple sclerosis (MS) involves an immune-mediated process in which an abnormal response of the body’s immune system is directed against the central nervous system (CNS), which is made up of the brain, spinal cord, and optic nerves. The exact antigen, or target that the immune cells are sensitized to attack, remains unknown, which is why MS is considered by many experts to be "immune-mediated" rather than "autoimmune."
The prevalence of obesity among adults and adolescents/children in the US is approaching 40% and 20%, respectively. Obesity consumes >20% of healthcare expenditures and accounts for an estimated $750 billion in lost productivity each year. Worldwide, the prevalence of obesity is on the rise and it has been estimated that obesity is currently responsible for 4 million deaths annually, 70% of which are due to cardiovascular diseases, and 120 million disability-adjusted life years.
Osteoporosis is a metabolic bone disease in which bone resorption exceeds bone formation, thus resulting in pathologic microarchitectural changes, low bone mass, and bone fragility. According to the National Osteoporosis Foundation, the prevalence of osteoporosis in the US is nearly 10 million, and approximately 2 million fractures occur annually. One-half of all post-menopausal women will sustain an osteoporosis-related fracture, primarily a result of aging and hypoestrogenism.
Ovarian cancer arises in the ovaries and is of three main types: epithelial, germ cell and stromal. In most women, ovarian cancer is diagnosed in an advanced stage and can be difficult to successfully treat/cure. Ovarian cancer is the fifth most common cause of cancer-related deaths in women in the US. It is estimated that 22,440 new cases of ovarian cancer will be diagnosed and 14,080 women will die from ovarian cancer. The lifetime risk of being diagnosed with ovarian cancer is 1 in 75.
Parkinson's disease (PD) is a chronic, progressive disease that is a movement disorder. Nearly one million people in the US are living with Parkinson's disease. The cause is unknown, and although there is presently no cure, there are treatment options such as medication and surgery to manage its symptoms. Parkinson’s involves the malfunction and death of neurons in the brain. Parkinson's primarily affects neurons in an area of the brain called the substantia nigra.
Prostate cancer begins when cells in the prostate gland start to grow uncontrollably. The prostate is a gland found only in males. It makes some of the fluid that is part of semen. Almost all prostate cancers are adenocarcinomas. These cancers develop from the gland cells (the cells that make the prostate fluid that is added to the semen). Other types of prostate cancer include: sarcomas, small cell carcinomas, neuroendocrine tumors, and transitional cell carcinomas.
Psoriasis is a chronic inflammatory disease with several forms (chronic plaque, guttate, pustular, erythrodermic, inverse, and nail psoriasis), all of which are characterized by epidermal keratinocyte hyperproliferation. The pathogenesis underlying psoriasis has not been completely elucidated, but T-cell dysfunction and hypersecretion of TNF-α appear to be key features. Psoriasis affects approximately 2% of the US population and is more common in residents of northern states.
Renal cell carcinoma (RCC) is the most common type of adult kidney cancer, accounting for 85%-90% of cases. The cancerous cells typically develop in the lining of very small tubules. Over time, these cells may grow into a mass and cause an obstruction. The cancer may form in one or both of the kidneys. Subtypes of RCC include clear cell RCC, papillary RCC, chromophobe RCC, collecting duct RCC, and unclassified RCC.
Rheumatoid arthritis (RA) is the most common type of autoimmune arthritis. It is triggered by a faulty immune system, and affects the wrist and small joints of the hand, including the knuckles and the middle joints of the fingers. For most people with RA, early treatment can control joint pain and swelling, and lessen joint damage. Studies show that people who receive early treatment feel better sooner and more often, and are more likely to lead an active life.
Seizure clusters are repetitive seizures that, unlike status epilepticus, are not life-threatening and exhibit complete recovery between seizures. Although a clinical definition of seizure clusters has not been established, 3 seizures within 24 hours is generally used. Seizure clusters are more common in patients with drug-resistant epilepsy (reported prevalence range, <10% to >60%) and it is unknown whether clusters represent impaired cessation of an ictal focus or increased neuro-excitability.
It has been estimated that sleep apnea affects up to 18 million adults in the US (30% of males and 15% of females), 80% of whom are undiagnosed. The prevalence of sleep apnea is on the rise in parallel with the increase in prevalence of obesity, the most important non-structural risk factor for sleep apnea. Sleep apnea is an important risk for cardiovascular diseases independent of obesity, and interestingly, treatment of sleep apnea does not ameliorate the risk for cardiovascular diseases.
Greater than 400,000 deaths are attributable to cigarette smoking in the US each year, making it the leading cause of preventable deaths. While the benefits of smoking cessation (decreased mortality, years of life lost, and smoking-associated diseases) are undisputed, no such benefit has been demonstrated for a reduction in the number of cigarettes smoked. In contrast, the risks of smoking cessation are negligible (nicotine withdrawal, weight gain, and affective disorders).
In 2013 the American College of Cardiology and American Heart Association issued revised recommendations for the primary prevention of atherosclerotic cardiovascular disease events in adults 45-75 years of age based on a 7.5+% risk threshold, which yield a cost-effectiveness of $37,000/quality-adjusted life-year. If the guidelines are followed, 8.2 million adults would be treated and, at the 7.5+% risk threshold, up to 160,000 cardiovascular disease-related deaths are averted each year.
Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that is thought to arise from defective apoptosis, reduced clearance of cellular debris, and aberrant exposure of nuclear and cytoplasmic antigens. SLE affects virtually any organ, but most commonly the skin, joints, kidneys, and hematopoietic and nervous systems. According to the Lupus Foundation of America, the prevalence of SLE in the US is approximately 1.5 million, with greater than 90% of cases involving females.
Type 2 diabetes is a chronic condition that affects the way your body metabolizes glucose, your body's important source of fuel. With type 2 diabetes, your body either resists the effects of insulin or doesn't produce enough insulin to maintain a normal glucose level. More common in adults, type 2 diabetes increasingly affects children as childhood obesity increases. There's no cure for type 2 diabetes, but you may be able to manage the condition by eating well, exercising and other changes.
Acute wounds become chronic wounds when the wound healing cycle is interrupted. The presence of necrotic tissue, foreign material, and/or bacteria lead to abnormal matrix metalloproteinase production, which in turn inhibit the inflammatory response within the epidermis. Of the 5 phases of wound healing, stalled inflammation is the basis for poor wound healing in most cases of chronic surgical and traumatic wounds and slow-healing venous, pressure, diabetic, and ischemic ulcers.
Zika virus is a neurotropic virus that is transmitted by mosquitoes, and has been isolated from all body secretions of infected humans. Zika virus was first described in Uganda in 1947, and is believed to have first occurred in the Western hemisphere in 2013–2014. The current outbreak of Zika virus involves North and South America, the Caribbean, and the Pacific islands. Preventive measures include mosquito protection, barrier contraception, and blood and tissue donor deferral.