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Influenza A (H3N2) Variant Virus

Posted by Paul

The influenza A (H3N2) virus is labeled as a variant virus because it normally circulates in pigs however it is found in humas as well. Influenza A (H3N2) variant viruses carry the (M) gene that was present in the H1N1 virus from 2009 and human cases involving this virus were first detected in July 2011. The viruses were present in U.S. pigs in 2010. From July to December of 2011 12 cases of the H3N2 virus were detected in the U.S. From January to September of 2012, 307 cases of the H3N2 infection were detected across 12 states. It is believed that these infections occured because of prolonged contact with pigs at agricultural fairs. There have been some cases where human to human contact spread the disease however there has not been a major outbread due to this type of contact. Scientist believe that sporadic outbreaks of this virus will occur due to human to human contact however they will not be sustained. The Centers for Disease Control reccomends covering your nose and mouth when you cough as well as washing your hands with soap and water frequently throughout the day. If soap is not available you can use an alcohol based hand sanitizer. If you become ill stay at home until your illnes is gone in order to prevent infecting your co-workers/classmates.

Fluorescence Microscopy

Posted by Paul

Fluorescence microscopy is a technique where a microscope uses fluorescence to create an image. A sample is illuminated by light of an excitation wavelength and it emits light of a longer wavelength which is collected by the objective. A filter cube is placed in the light path and is located above the objective. The filter cube consists of an excitation filter, dichoric mirror and an emission filter. Xenon arc lamps and mercury-vapor lamps are used as light sources. Light passes through the excitation filter and reaches the sample. The sample is tagged with a fluorophore which releases light in a specific wavelength range. This light then passes through the emission filter and reaches the eyepiece. The dichroic mirror reflects the excitation light while allowing the emission light to pass through. Prior to being viewed with a fluorescent microscope samples must be prepared properly. This may involve the immunostaining of cells. This is a process in which an antibody binds to a specific protein within the cell. A secondary antibody conjugated to a fluorophore may be used to bind to the primary antibody. It is the fluorophore conjugated to the secondary antibody that emits the light that eventually passes through the emission filter.

Post Flood Mold

Posted by Paul

Anyone who is a flood victim of hurricane sandy should be aware of the dangers of post flood mold in their residence. Molds are fungi that can be found indoor or outdoors. Some estimates state that there are up to 300,000 species of mold however the total number is unknown. Molds thrive in moist, humid, warm environments and reproduce by producing spores that are highly resistant to harsh conditions. The most common indoor molds are Cladosporium, Penicillium, Alternaria, and Aspergillus. The Institute of Medicine has found that there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough and wheeze within healthy people. Mold exposure can also exacerbate asthma. If mold is found in your place of residence it must be removed immediately. One cup of bleach in one gallon of water will be sufficient to remove and kill the mold. The Environmental Protection Agency should be contacted if an area larger than 10 square feet is infected with mold. The flooding caused by hurricane Sandy will not only increase the probability of mold growth however it will also increase the growth of pathogenic bacteria.

Fungal Meningitis

Posted by Paul

A recent outbreak of fungal meningitis has affected 271 patients across several states who received contaiminated steroid injections. This outbreak has caused 21 deaths and is being traced back to the compounding pharmacy that prepared the spinal steroid injections. The specialty pharmacy has since recalled three lots of the drugs. The CDC and FDA have confirmed the presence of a fungus known as Exserohilum rostratum in unopened vials of the drug methylprednisolone. Laboratory testing on the other two lots that are thought to be contaminated continues. The CDC and various health departments etimated that 14,000 patients have received shots from the contaminated lots and roughly 97% of these patients have been contacted. Meningitis affects the membraneous lining of the brain and spinal cord. Early symptoms include headache, fever, nausea and dizziness. Some of these symptoms can take up to a month to disappear. If fungal meningitis is left untreated it can cause permanent neurological damage and death. paul n.

Student Microscope

Posted by Paul

What makes a good student microscope? There are many different types of microscopes on the market and with the holidays around the corner now is a good time to talk about what features make a good student microscope. You may see microscopes with mirrors beneath the stage however these types of microscopes are not recommended for students. A built in light will provide better illumination than a mirror thus contributing to the overall resolution of the optical system. A mechanical stage is also highly recommended for student microscopes as this gives the user more precise control over the movement of the slide. At higher magnifications one can easily move the specimen outside of the field of view by moving the slide with their fingers. A mechanical stage allows one to move the slide very short distances. Having coarse and fine focus controls is important as well. The fine focus control allows the user to sharpen the image to obtain better resolution. Finally, the fourth feature of a good student microscope is a binocular head. Viewing a specimen through a monocular head tends to lead to eyestrain. Manufacturers such as Konus and Celestron make microscopes well suited for students of all ages.

Salmonella Outbreak

Posted by Paul

Recently there was a Salmonella outbreak in 16 states that affected 105 people that originated from Mangoes taken from a Mexican farm. Mangoes under the Daniella brand name distributed by Splendid Products contained this bacteria and first caused an illness in Canada. Salmonella is a gram negative, non-spore forming, motile species of bacteria characterized by their rodlike shape. Salmonella can cause illness such as typhoid fever, paratyphoid fever, and foodborne illness. Laboratory tests for Salmonella involve the use of TSI agar which contains ferrous sulfate. This agar allows easy identification of Salmonella because they product hydrogen sulfide. The majority of salmonella infections are due to contaminated food. Salmonella must be ingested in large numbers to cause disease in heatlhy adults. The acidic nature of the stomach destroys the majority of ingested bacteria. When outbreaks such as this occur, each case is reported and the source of contamination can usually be traced back to its source. Produce is sold under specific lot numbers which are tracked to various grocery outlets.

West Nile Virus

Posted by Paul

The West Nile virus is spread by way of mosquitos biting infected birds then biting humans. It was first identified in Africa in 1937 and the first case in the U.S. occured in New York in 1999. Since then it has spread west throughout the U.S., into Canada and into the Caribbean. The virus has also been found in ticks however mosquitos are considered the most important host. Almost 80% of West Nile virus infections do not cause any symptoms. When symptoms do occur their onset is immediately after the infection. Symptoms can include fever, headaches, fatigue, and muscle pain. Mosquito saliva is a cocktail of proteins that can affect vaso constriction as well as other characteristics of the immue response. Scientists do not know what benefit the virus offers to mosquitos. There is currently no vaccine and the best method of prevention is mosquito control.

Differential White Blood Cell Count

Posted by Paul

A differential white blood cell count is used to determine the relative percentages of various types of cells within a blood sample. Elie Metchnikoff proposed the theory of phagocytic immunity at the Pasteur Institute in 1883. He stated that large cells in the blood stream are responsible for defense against bacterial infections. Neutrophils, eosinophils, basophils, lymphocytes, and monocytes are the five types of cells in the blood responsible for engulfing foreign bodies in the blood. Wright’s stain is used to make these cells more visible under the microscope. When these cells are not stained they are colorless structures. During a differential white blood cell count 100 cells are counted using a differential counter and the percentage of each type of cell is determined. Neutrophhils are typically the most abundant making up 50-70% of the sample. There are between 5,000 and 10,000 white blood cells per cubic millimeter in a normal white blood cell.

Slide Agglutination Test

Posted by Paul

Microorganisms of different species differ not only in their morphology and physiology but also in various components that make up their molecular structure. The proteins, polysaccharides, nucleic acids and lipids define the molecular structure of an organism. Some of these macromolecules act as antigens because they stimulate the formation of antibodies when introduced into an animal. The antigenic structure of each species of bacteria is unique to the bacteria and just like a fingerprint, it can be used to identify that bacteria. Some species of bacteria are physiologically identical yet have different antigens. These species are referred to as serotypes. The slide agglutination test can determine the antigens of a microorganism. This method involves placing a suspension of cells on a slide then adding antiserum containing antibodies specific to that antigen. If the cells agglutinate or form clumps then the unknown species can be identified. This method is used in the identification of Salmonella and Shigella that cause infections in humans.

Stereo Microscope

Posted by Paul

What is a stereo microscope? A stereo microscope is a microscope that allows the user to view objects in three dimensions. A stereo microscope mimics the way your eyes look at objects so you are looking at a true image. The more widely known compound light microscope is used to view specimens mounted on slides and provides the user with a virtual two dimensional image. For applications such as viewing stamps, rocks, coins, insects, and circuit boards a stereo microscope would be more applicable. Larger objects such as the ones previously listed require a larger working distance or the distance from the object to the front of the microscope lens. The working distance of objectives on a compound microscope can be as high as 30mm for a 4x objective and as low as .23mm for a 100x objective. The working distance of a stereo microscope can go up to 170mm. This allows the user to manipulate the object beneath the objective lens. Stereo microscopes make great gifts for young learners because you can immediately view objects under the microscope without having to prepare slides as is the case with compount microscopes.