Growth of Tumors

When an overgrowth of tissue forms into neoplastic mass, it’s called a neoplasm or tumor. Neoplasia can have a deadly outcome such as in cancer. It is the No. 2 killer in North America with 30 percent suffering from the disease. A quarter of North American adults die of cancer. It also kills more children than any other disease.

Oncology is the study of tumors and when we talk about tumors, there’s two important characteristics – pattern of growth and tissue of origin. A tumor is benign if growth is slow, orderly and the tumor is localized. It’s malignant if the growth is rapid, disorderly and invades other normal tissues. Cancer is result of a malignant tumor that spreads to distant points in the body.

We add the suffix “-oma” when designating a benign tumor and what in which tissue it originates. An osteoma is a benign tumor in bone. A fibroma is a benign tumor in fibrous tissue.

If a malignant tumor arises, then it is named depending on which embryonic tissue it originates from. If from the ectoderm or dndoderm, then it’s a carcinoma (usually skin and epithelial linings). If it’s a glandular tumor, then it’s called an adenocarcinoma. If it occurs in the mesoderm, then it’s a sarcoma such as a chondrosarcoma or fibrosarcoma.

Then, there are exceptions, such as melanoma, lymphoma, and hepatoma which sound benign but are actually malignant. Malignant tumors in leukocyte-producing tissues are myeloid leukemia (red bone marrow) and lymphcytic leukemia (lymphoid tissue).

A benign tumor’s cells are about normal size and shape and pretty much looks like normal tissue, but a malignant tumor is very pleomorphic, enlarged and contains abnormal nuclei and chromosome structures. Sometimes the cells are huge because they fail to undergo mitosis.

Benign tumors grow faster than normal, but are slower than malignant tumors. They also have a fibrous connective tissue capsule surrounding the mass, which creates a distinct line to separate it from normal tissue. Generally, the slow growth causes less damage and surgical removal leads to a pretty good prognosis.

Malignant tumors grow quickly and are aggressive in their invasion. They send whole columns of cells to disrupt other normal tissues. They rarely come within a capsule as the benign tumors do. The line is blurred between malignant tumor tissue and normal tissue. Metastasis is a major factor causing a poor prognosis as growth at primary sites usually lead to establishment of tumors in secondary sites.

A spread of malignant tumor to secondary sites increases damaging effects. The metastasis of tumor cells often are carried by blood or lymph. If the invasion of a vein or lymphatic vessel occurs, then an emboli is formed that is used to gain access to a secondary site. Capillaries and lymphatic vessels are easily invaded, especially by carcinomas.

Metastasis can also involve spreading through body cavities. These can include adenocarcinomas shedding from the pancreas into the pelvic cavity or when a neuroblastoma from a the medulla oblongata spreads to the subarachnoid space invading the spinal canal.

Iatrogenic metastasis is rare. It occurs when medical intervention introduces tumor tissue to a site to develop into a secondary tumor.

Tumors growth at primary and secondary sites impairs normal functions. Malignant tumors cause continual increased damage, which generally overwhelm the body despite therapy.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

Green tea could lead to longer life by protecting DNA

Last year, scientists from The Chinese University of Hong Kong found a positive association between high consumption of tea (Camellia sinensis) and longer telomere length – a marker of younger “biological age” – and living an average of five years longer, but it was unclear just how much of an impact was made by the tea.

Now scientists from Hong Kong Polytechnic University have discovered, through a cell culture study then followed by a controlled trial of supplementation in humans, that drinking two cups of green tea daily may offer notable DNA protection from oxidation.

Writing in the September issue of British Journal of Nutrition, the study’s authors state that the “genoprotective effects of green tea lend support to its use as a functional food and provide scientific evidence for the more confident recommendation of regular intake of green tea for health promotion.”

In the in vitro trial, the scientists prepared an infusion of tea that was used to treat human immune cells. The cells were then immediately exposed to hydrogen peroxide, a highly reactive oxidant, which showed a significant decrease in DNA damage.

In the single-blinded, crossover trial, 18 healthy, nonsmoking adults (ages 35 to 50) drank two cups (150 mL) of either freshly prepared green tea (Longjing or screw-shaped) or hot water (as a control) daily. All subjects randomly received their tea or water for four weeks, then had six weeks of washout period before starting on the next four weeks of tea or water.

The researchers collected blood samples and tested cells before and after supplementation when exposed to hydrogen peroxide. Tea drinkers had a 30 to 35 percent decrease in DNA damage.

Despite antioxidant content of green tea, the authors write that this study found no evidence of whole-body oxidative stress reduction in humans as measured by a urine biomarker. However, the study helps establish that drinking green tea delivers a targeted “antioxidant” action protecting cells against oxidation.

Green tea’s protective effects are thought to be dependent on its content of antioxidant polyphenols, which include its main polyphenol, epigallocatechin gallate (EGCG). Numerous studies in animals and humans have linked EGCG to positive health outcomes including better weight management, cellular health, heart health, and even longer life. This particular study did not investigate benefits of supplementation with EGCG as a green tea extract or benefits beyond protection of cell DNA.

Sources:

Chan R, Woo J, Suen E, Leung J, Tang N. Chinese tea consumption is associated with longer telomere length in elderly Chinese men. Br J Nutr. 2010 Jan;103(1):107-13. Epub 2009 Aug 12.

Han KC, Wong WC, Benzie IF. Br J Nutr. 2010 Sep 1:1-8. Genoprotective effects of green tea (Camellia sinensis) in human subjects: results of a controlled supplementation trial.

How the healing process really happens

Healing is a pretty fascinating process that our body is capable of producing all on its own in response to destroyed tissue. The process replaces lost tissue and restores structure, strength and function. It’s intertwined with inflammation and so there’s overlap between the responses as you’ll note after reading these posts and previous ones.
It all happens when tissue that is undamaged next to the damaged tissue begins to proliferate. Functional cells called parenchyma combine to form a stroma. Then, there’s two different ways healing takes place: regeneration or repair. Regeneration is when tissue is replaced. Repair is when fibrous car tissue is used to fill gaps.

Basically, reestablishing epithelium at damaged spots come with four components:

– Regeneration: This is when cells lost are replaced by mitosis by adjacent parenchymal cells. It’s ideal because new tissue is ideal for normal function.

– Repair: This is when fibrous connective tissue, or a scar (made of strong collagen) is used to restore structure, but can’t regenerate. Fibroblasts are up to the task of creating fibrosis since they tend to resist damage from injury.

– Revascularization: Despite whether or not regeneration or repair has happened at the site of injury, revascularization, or angiogenesis, restores blood supply. It is the process of production of new blood vessels coming to the site to supply nutrients.

– Surface restoration: When mitosis is happening at a site of injury, the new cells migrate to the edge and onto the surface where the injury is. They begin to organize secreting new basement membrane and when the edges meet, they become anchored in the membrane.

Primary healing is what we say to describe healing of a severing of a wound, or incision. There’s only minor damage with wound edges close to eachother. Bleeding narrows the gap, a clot forms, then a scab, an exudates and then a newly restored surface.

Secondary healing happens when wounds’ edges are not so close. They can happen commonly in skin and the GI tract (such as from a duodenal ulcer). The large wounds produce a lot more debris. The restoration process is extensive. Granulation tissue formation is needed to fill the wound gap, then there’s the aspect of wound contraction. The wound edges come closer toward the center through contraction that reduces the size of the gap. The contraction is caused by myofibroblasts, which are like modified fibroblasts that are derived from pericytes, which have the ability to contract.

Healing tissues

Connective tissue healing is prolonged because of a limited blood supply. Bone, or osseous tissue, has great regeneration abilities because of osteoblasts that are held in reserve, which work with osteoclasts to remodel bones. Tendons and ligaments can jusually recover from injury, but a bad injury can result in scar tissue or rough surface that causes weaker tensile strength or function. Cartilage heals by fibrous repair. Adipose tissue can’t go through mitosis, but precursor cells differentiate to produce new tissue.

Epithelial tissue can regenerate easily enough. They are frequently subject to injury. Regeneration will occur if epithelium damage is superficial. It can’t happen, however, if the basement membrane or intercellular matrix is disrupted, so in these cases fibroblasts will repair with scar tissue.

Glandular tissues are pretty stable and when injured they simply regenerate new tissue. For example, liver can regenerate very well. But if there’s serious damage, then there might be some functional loss.

Nervous tissue is made up of neurons that can’t go through mitosis, so if they’re damaged, then they’re replase by gliosis or proliferation of neuroglia. The neuroglia create a scarlike mass to block damaged axons to grow any further. Peripheral nervous system can replace myelinated neurons if Schwann cells stay undamaged.

Muscle tissues are permanent, so when damaged there is only fibrous repair causing loss of function. But muscles have compensation capabilities. The muscle cells increase in size and strength, called hypertrophy, which is what you get when lifting weights.

Healing problems

Sometimes healing doesn’t go so well. If the damage is too much, then collagen causes an exaggeration in wound contraction process called contracture. This can create distortion, such as seen in disfiguration after serious skin burns.

A second problem are adhesions, which result from inflamed exudates between serous membranes. These cause restriction in movement such as after surgery of heart or lungs, which sometimes require patients to be readmitted due to complications.

Dhiscence is when a healing wound breaks open because of pressure on the tissues. This happens most commonly in the abdominal wall because pressure interferes with formation of maturing collagen. It can lead to violent episodes of coughing, vomiting or diarrhea. A deficiency of vitamin C could also cause dehiscence problems.

Keloids are masses of scar tissue that are protruding through skin. They happen when dermal collagen is overproduced. Proud flesh is a problem of excess granulation tissue. Suture complications can result in cases when keratin is sealed within a suture tract.

Lastly, therapy sometimes can interfere with healting as in radiation or chemicals used in cancer. And anti-inflammatory or immunosuppresants can stop protein synthesis, wound contraction and regeneration.

Controlling healing

Healing is regulated closely, but not well understood. We know of two categories of chemical control factors including growth factors and growth inhibitors. As their names imply, they act in antagonistic ways promoting growth and stopping it. They are vital for migration of fibroblasts and epithelial cells, as well as formation of blood vessels, mitosis, and collagen formation.

Healing depends on cell interactions, especially in the extracellular matrix. Receptors on fibroblasts allow for binding elements of intercellular material. So, the matrix plays a role in regeneration and repair. The matrix interactions provide the regulartory input for healing as long as it is available undamaged.

Somehow, contact between cells physically regulates mitosis. In other words, cells undergoing mitosis stop once contact inhibition happens. You can see this in cells growing in laboratories. They start dividing and migrate, but when they meet they stop.

Worth noting is that growth factor therapy is being studied to better control healing in the future. Preparations of various growth factors could be used for therapy in several instances. Such as burn victims.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

How cell injury happens and what is the result?

A normal cell has a general organization at a chemical level that involves atoms, molecules moving around in complex fashion that ultimately is critical to the way we live. The cell membrane and various organelles such as the mitochondria all have vital roles to play.

At the cellular level, injury is a result of three basic causes: deficiency, intoxication, or trauma. A deficiency is when the cell lacks a compound of a sort that causes interference with function such as when there’s a dietary deficiency of B vitamins. Intoxication is when a compound present actually poisons the cell, interfering with function such as when a biological infection, or toxic product in the cell like barbiturates. Trauma is when there is actual physical injury to the cell, causing loss of cell integrity such as hypothermia causing ice crystals or hyperthermia causing denaturation of cellular proteins.

The cell can respond in various ways by adapting with reversible (functional or structural) and, sometimes, irreversible (structural or deadly) changes.

The reversible may include alternative metabolisms such as in hypoxia when the cell changes from oxidative phosphorylation to glycolysis, or with altered size as in hypertrophy when demand increases. Reversible changes also include apoptosis that reduces cell numbers, production of cell-stress proteins (like heat stress or heat shock proteins) or organelle changes to make certain enzymes available as in detoxification.

There are also fatty changes as in the liver, residual bodies that are derived from phagosomes when lysosomes aren’t enough, and hyaline changes when proteins accumulate in a cell.

Structural reversible changes include blebs that project out of a cell and myelin figures that are membrane structural abnormalities.

Irreversible injury to cells involve unrecoverable structural changes to the cell membrane causing increased permeability or spillage. It can also involve similar changes to mitochondrial membranes or the structure of other organelles.

Cell death is an irreversible injury called necrosis. Unlike apoptosis, it’s not programmed. It can happen due to coagulation, when proteins are denatured quickly because of acid, heat or enzymes. Caseous necrosis happens as a type of coagulation necrosis in tuberculosis causing a cheeselike appearance. Gangrenous necrosis is another kind that happens when toxic metabolites of bacteria cause reduced blood flow and produce putrefaction.

If coagulation doesn’t occur, and tissue breaks down quickly because of lysosomal enzymes then liquefaction necrosis has resulted.

Calcification is a deposition of calcium crystals at sites of necrosis. It occurs when cell injury allows calcium into the cell condensing in mitochondria and causing death. The calcium crystals can start out tiny, but become large masses in a process called dystrophic calcification.

And, when calcium is deposited only as a result of excessive calcium, as in hypercalcemia, then metastatic calcification has occurred. Generally, metatstatic calcium deposits are not severe, but can interfere with lung or kidney function.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

The basics of health and disease

What does healthy mean? Some would call it the absence of disease, or when a person can fully use all of his or her physical or mental capacities. But when what we understand as the concept of health is disrupted, in some way or another (which happens inevitably), we call it disease.

The study of the cause of this disease is what we call etiology and the field of etiological study can be specific, as in viral etiology or genetic etiology. Or, when the etiology of a disease is unknown, then idiopathic.

Unlike genetic etiology (think cystic fibrosis), which comes with a genetic structural or functional defect, congenital etiology has to do with factors affecting an embryo’s development in utero (think fetal alcohol syndrome).

The largest category of etiology is acquired disease. These are diseases that develop despite normal genes and embryonic development. Think everything else from tuberculosis to flu, to heart disease and cancer.

Diseases come with symptoms, signs or both. Signs are what is observable by another person – like clammy hands, fever, or irregular pulse. Symptoms are those that are found through physical examination with lab tests, x-rays, surgery.

When there’s a combination of signs and symptoms associated with a disease, we call it a syndrome (as in metabolic syndrome, Down’s syndrome).

After an examination of signs and symptoms, the pattern of development of the disease is pathogenesis. The pathogenesis could describer some kind of initial impact that produced the disease. The resulting condition is a sequela. If the pathogenesis had a rapid onset, it’s acute, and if it develops over time of months or years, then it’s chronic. When pathogenesis involves minor changes, the onset is said to be insidious.

The diagnosis, or identification, of a disease happens (or should happen) after a complete analysis of signs and symptoms with pathogenesis explained. Then, therapy follows with the goal of curing or reducing a patient’s signs or symptoms. The prognosis is the analysis of how a body responds to the therapy.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

What is inflammation?

Inflammation is a normal response of the body that involves an increase of blood flow to a site of injury. The signs of inflammation are redness (rubor), heat (calor), swelling (tumor) and pain (dolor). One other classic sign is loss of function (function laesa).

Acute inflammation is a dramatic localized response to injury. It comes vascular changes increasing blood flow (hyperemia) to the area that cause the redness and warmth as observed along with swelling. There’s also a cellular component, in which large numbers of white blood cells move to the injury to stop infectious agents and clear debris. The cells that come form what is referred to as an exudates.

Chronic inflammation is when inflammation lasts beyond six weeks (subacute applies to inflammation beyond a week, but not lasting as long as six weeks). A chronic response can last months and years. It is essentially a “standoff” between an injury and the body’s defense. They resist each other, but neither is strong enough to beat the other down.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

What causes a fever?

When inflammation comes with a body temperature that is elevated above normal, we call it a fever or pyrexia. The change in temperature is not a defect, but an adjustment by the hypothalamus to a new set point. The set point is established in consequence of release of fever-producing factors called pyrogens, whether endogenous or exogenous. Endogenous pyrogens are produced upon stimulation of exogenous agents.

The fever is a response to infectious, toxic or immunologic disease or injury, at least in warm-blooded animals – although cold-blooded animals like lizards often treat themselves similarly by lying in the sun to raise body temperature.

The fever enhances functions of the immune system and phagocytosis. Also, there are a few bacteria and viruses that reproduce more slowly in the heated temperature because of possible interference with uptake of iron.

So, our initial idea of a fever as something to treat may actually be our bodies’ ways of treating themselves to some kind of moderate degree. But antibiotics are a modern intervention that have given us the capacity to thwart the need of suffering through a fever.

Besides, a fever can actually cause damage itself as in the brain or in pregnancy. The excess heat can cause hyperthermia that creates cranial pressure or can harm a fetus, respectively.

Antipyretic therapy, such as with acetylsalicylic acid, is the way to go. They inhibit prostaglandin production in they hypothalamus, which results in a block of the set point elevation and returns temperature to a normal level.

But children with flu or measles shouldn’t take acetylsalicylic acid because of association with Reyes syndrome, so ibuprofen or something else should be used for children.

Reference

Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.

Giving Children the Chance at a Healthy Future

Encouraging healthy habits like exercise and eating right early on helps stave off childhood obesity.

September is the first-ever officially proclaimed National Childhood Obesity Awareness Month in the United States. It’s a dedicated time for recognizing the seriousness of obesity on health and building awareness about the rise in obesity rates and its impact on our youth.

The government statistics about childhood obesity are shocking:

– Childhood obesity has increased more than fourfold among ages 6 to 11 in the United States

– More than 23 million children and teenagers in the United States ages 2 to 19 are obesity or overweight

– Nearly one third of America’s children are at early risk for Type 2 diabetes, high blood pressure, heart disease and even stroke

– The current generation may have shorter lifespans than their parents

During this month of national attention on this epidemic, parents and responsible adult role models can surely do their part by encouraging the overall goal of living a healthier lifestyle, one that emphasizes healthy habits such as eating right and exercising regularly – whether a child is an infant, toddler, pre-teen, or teen.

Infant Introductions

A newborn’s nutritional needs are met almost entirely through breastmilk or formula, but by six months dietary habits can begin to develop with the introduction of solid foods. The foods that a baby eats can shape preferences later in life.

Parents should seek to give infants solid foods – fortified infant cereals and strained fruits, vegetables, and pureed meats – that emphasize natural whole food flavors and that are not sweetened with added sugars. During this stage in life, it’s also well-heeded advice to avoid introducing fruit juices or any kind of sugar-sweetened drinks.

Tips for Toddlers and Preschoolers

As infants grow into toddlers, their energy grows and so do their appetites for snacks. Most snacks, unfortunately, come in the form of sodium, starch and fat – buttered noodles, potato chips, French fries – and too little protein, fiber and vitamins and minerals.

Parents can promote snacking on whole foods by having fresh whole fruits and vegetables readily available and in easy reach to children. Plus, they can encourage drinking of water and milk by keeping fruit juices and sugar-sweetened drinks such as soda pop out of reach.

By the time children are in preschool they may have already discovered sedentary activities such as television and videogames. However, adults can help children get the exercise they need by providing toys like tricycles and taking them to visit to the park and playground regularly.

Elements of Elementary School Age

When children reach elementary school, they are ready to learn the basics of making time for regular physical activity and making good food choices for maintaining a healthy weight.

Keeping kids moving can be as simple as getting them involved in regular activities: children can help with daily chores such as sweeping, vacuuming or gardening; or they can get signed up for team or individual sports such as swimming, gymnastics, dance, soccer, T-ball and basketball. The goal is anything that keeps them off the couch.

Parents can provide children with guidance on food choices by teaching them guidelines – such as those given by the Food Guide Pyramid – or by simply providing direction at home and when eating out. For example, at restaurants, adults can encourage healthy alternatives such as apples instead of French fries.

Puberty Principles

Preteens and teens begin to become more conscious of weight and body image. So, parents should keep a close watch for potential eating disorders or other possible unhealthy behaviors. Parents should reinforce positive behaviors such as healthy eating patterns and regular exercise.

Tweens with large appetites often need guidance in understanding the value of portion size, nutrient density, and balance in meals for nutrition and weight management. Parents can help by teaching how to watch amounts of calories, sugar, salt and fat, while identifying foods higher in fiber, protein, and calcium.
Exercise can begin with recreational activities, individual and team sports. At preadolescence, however, outdoor activities like hiking, boating, and snowboarding can also be exciting, which lend parents more opportunities to encourage physical fitness.

Health Begins at Home

At any age, there’s no better way to help a child to adopt the habits of a healthy lifestyle than by setting an example – that means adults adopting healthy habits too.

Parents should become involved with exercise for children by picking activities that the whole family can enjoy such as bike rides, nature walks and games. Parents can also get children involved in preparing healthy meals at home and eating them together.

In addition, parents can reward children’s healthy behaviors to keep them motivated, which invites them to adopt healthy habits for life that ultimately a better future.