Archive for the ‘cells’ Tag

Admirable Clarity


How many cells are there in our body? This simple question deserves a simple answer. Some types of cells are easy to spot, while others–such as tangled neurons–weave themselves up into obscurity. Even if you could count ten cells each second, it would take you tens of thousands of years to finish counting. Plus, there would be certain logistical problems you would encounter along the way to counting all the cells in your body; for example, chopping your own body up into tiny patches for microscopic viewing.

If scientists can’t count all the cells in a human body, how can they estimate it? The mean weight of a cell is 1 nanogram. For an adult man weighing 70 kilograms, simple arithmetic would lead us to conclude that man has 70 trillion cells. Cells are the building blocks of the human body, but what is the total number of cells in a human body remains still a riddle. It is estimated that the body of an average person contains around 30 to 40 trillion cells, but scientists do not yet know the exact number and it also depends on whether or not one include the bacteria that are present in and on our bodies. The majority of the cells in our bodies are red blood cells. They make up over 80 percent of our body in number and comprise only around 4 percent of total body mass. This is because red blood cells only measure on average 8 micrometers in diameter, which is 10 times small in diameter than an average human hair.

The average size of a fat cell is 100 micrometers. The fat cells make up nearly 19 percent of our body mass. They contribute only under 0.2 percent to the total cell number. Calculating the actual cell number of the five most common cell types in an average adult male, which account for 97 percent of the cells in the body, the estimation is about 30 trillion cells, of which red blood cells make up 84 percent.

The human cells are not the only cells in our bodies. There are 10 times as many bacteria in our bodies than human cells and scientists estimate this number to be around 38 trillion. Although, large in number, bacteria are much smaller than human cells, and they actually make up only 200 grams of our total body mass. We are as much bacteria as we are human, bringing the total number up to around 70 trillion. The bacteria present in our body counts more in number than human cell, except these measure 200 gm only and that is really amazing.

This is not a final number, but it is a very good start. While it is true that people may vary in size and thus vary in their number of cells; adult humans do not vary by orders of magnitude except in the movies.

Each of our cells has over a hundred thousand machines within it, including DNA, which is a molecular machine that is not alive. DNA is composed of molecules that are not alive which are composed of atoms that are also not alive. In actual fact, our body is a type of cybernetic organism made of both organic and biomechatronic body parts.


Nanoparticle Paste Heals Bone Imperfections

After accidents or cancer surgery, surgeons have to transplant healthy bone tissue or synthetic material to repair the ensuing bone imperfection. Regrettably, these measures do not always have the preferred effect. Now Prof. Matthias Epple and his team at the University of Duisburg-Essen have developed a nanoparticle paste that can be injected into the defect and results in enhanced bone healing. Scientists have combined synthetic calcium phosphate with DNA.

The interface between biology and medical science has been investigating the impact of mineral tissue such as teeth, bone and sea shells for several years and is now using the information to create new biomaterials. The scientists teaming up with medical scientists fashioned the knowhow of this measure. The repair of bone defects is menacingly challenging for surgeons. When possible, surgeons collect the patient’s own bone from various locations, such as the iliac crest, and implant it where desired to fill defect. As there is only a limited amount of surplus bone material in the body, synthetic materials is the next best option. Calcium phosphate is a natural choice since it is an inorganic mineral found in bones in the form of nanocrystals. It is a material familiar to the body, which makes it a suitable carrier. The calcium and phosphate ions lead to improved new bone formation.

The use of synthetic materials creates a host of new problems. The bones heal more slowly, the risk of infection is greater and the mechanical stability is not ideal. Scientists have now created a bone repair paste by coating synthetic nanocrystals of calcium phosphate with nucleic acids, otherwise stated, with DNA. The nanoparticles are taken up by cells. The calcium phosphate dissolves and the DNA that is released stimulates the formation of two proteins important for healing; namely bone morphogenic protein-7, which stimulates bone formation, and vascular endothelial growth factor-A involved in guidance of vascular endothelial growth factor, which is accountable for the making of new blood vessels. As a result, the new bone is supplied with required nutrients.

The University of Duisburg-Essen scientists look forward that the paste will have a long-lasting effect as the nanoparticles are released successively and thus continuously stimulate the surrounding cells. The paste works in three different cell types. This amazing advance will be used several years from now in the field of traumatology and in the treatment of osteoporosis.

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