Do you know which fungus product used in Organ transplatation ?

The soil-inhabiting fungus Tolypocladiurn inflatum is the source of cyciosporin, a medication that suppresses the immune reactions that cause organ transplant rejections. Cyclosporin does not cause the undesirable side effects that other immune-suppressing medications do. This remarkable drug became available in 1979, making it possible to resume organ transplants. which had essentially been abandoned. As a result of cyclosporin. successful organ transplants are almost common place today.

What are Killed (inactivated) vaccines?

When safe live vaccines are not available, either because attenuated strains have not been developed or else because reversion to wild type occurs too readily, it may be possible to use an inactivated preparation of the virulent organism to immunize the host. The organism is propagated in bulk, in vitro, and inactivated with either betapropiolactone or formaldehyde. These vaccines are not infectious and are therefore relatively safe. However, they are usually of lower immunogenicity and multiple doses may be needed to induce immunity. In addition, they are usually expensive to prepare. In subcellular fractions ,when protective immunity is known to be directed against only one or two proteins of an organism, it may be possible to use a purified preparation of these proteins as a vaccine. The organism is grown in bulk and inactivated, and then the protein of interest is purified and concentrated from the culture suspension. These vaccines are safe and fewer local reactions occur at the injection site. However, the same disadvantages of poor immunogenicity and the need for multiple boosters apply.

What is the general course of development for cases of syphilis?

The etiologic agent of syphilis is the spirochete Treponema pallidum. The organism is motile and can be observed moving about under the dark- field microscope. It is extremely difficult to cultivate in the laboratory, and direct observation is usually required for diagnosis. The organism is transmitted among humans by sexual contact, such as during sexual intercourse.

The development of syphilis is generally an involved series of events. The primary stage consists of a painless, hard sore called a chancre at the site where spirochetes have entered the body(usually on the external or internal genital organs). After several weeks, the chancre disappears and a latent period ensues. The secondary stage appears many weeks or months later. The secondary stage is accompanied by a skin rash with pustular lesions and skin eruptions. The hair on the head and eyebrows is often lost. Liver inflammation is common, and an influenza like syndrome may appear. The person is highly contagious at this point. After some time, the lesions heal and another latent stage develops. A tertiary stage may appear years later. This stage is characterized by the formation of gummas, which are gummy, granular lesions that form in the brain and major blood vessels. The patient often becomes paralyzed and usually suffers permanent damage to the blood vessels. In addition, the symptoms of dementia may occur. Death usually accompanies destruction of the heart and blood vessel tissues.

One of the dangers of syphilis is the possible development of congenital syphilis. In this instance, the spirochetes cross the placenta and enter the fetal blood from the mother’s blood. Newborns show signs such as notched incisors (Hutchinson’s teeth), a perforated palate, an aged- looking face, and damage to the nose. Congenital syphilis may also result in stillbirth.

What happens once the DNA from the HIV particle enters the cell nucleus?

The DNA molecule, known as a provirus, assumes a relationship with the DNA of the T lymphocyte, and the provirus enters the state of lysogeny. From this point in the nucleus, the provirus encodes new HIV particles, which acquire their envelope by budding through the membrane of the T lymphocyte. The human body attempts to keep up with the mass of new viral particles, but eventually the newly emerging strains of HIV overwhelm the body defenses and the T lymphocyte count begins to drop. Normally, it is approximately 800 T lymphocytes per cubic millimeter of blood, but as the disease progresses, the count drops into the low hundreds and tens. This drop may occur as soon as weeks after infection or as long as 20 years or more after infection.

Are chromosomes the only parts of bacteria that can be transformed?

Bacteria possess extrachromosomal loops of DNA called plasmids. Plasmids are small, self-replicating loops of DNA with about 10 to 50 genes. They are not essential for the survival of the bacterium. New segments of DNA acquired in transformation may attach to the plasmids of a bacterium, or entire plasmids may be recovered from the local environment. Additionally, plasmids can sometimes be lost in a process called curing, which can occur spontaneously or can be induced by certain environmental factors.

Are there any unique ways that humans derive benefits from microorganisms?

Humans derive substantial benefits from the activities of microorganisms. For example, many microbial species live in and on various parts of the body and prevent pathogenic bacteria from gaining a foothold. These organisms are referred to as normal flora. Microorganisms produce many of the foods we eat, including fermented dairy products (sour cream, yogurt, and buttermilk), as well as fermented foods such as pickles, sauerkraut, breads, and alcoholic beverages. In industrial corporations, microbes are cultivated in huge quantities and used to produce vitamins, enzymes, organic acids, and other essential growth factors.

How can drug resistance develop in microorganisms?

The use of antibiotics over the last 60 years has led to the development of drug- resistant strains of bacteria.These bacterial strains always existed in the microbial population, but they never needed to use their resistance mechanisms because they were never confronted with the antibiotic. With widespread antibiotic use, the susceptible bacteria died off rapidly, and the surviving bacteria were those with resistance. They
quickly multiplied to form populations of drug- resistant microorganisms. While methicillin- resistant Staphylococcus aureus (MRSA) is a well- known example of a drug- resistant strain, many other organisms are showing alarming rates of drug resistance due to the selective pressures exerted by the increased use of antibiotics.

Are bacteria able to move, and, if so, how?

Bacteria (and other prokaryotes) have the ability to move by means of flagella. Flagella are composed of the globular protein flagellin. They are extremely long and thin and cannot be seen by the light microscope unless specially stained. They are, however, readily visible under the electron microscope. Bacterial flagella propel the organism by a rotary motion. Each flagellum has three basic parts: the filament, which is the long, outermost region containing the flagellin; the hook, which is composed of a different protein and lies at the proximal end of the filament; and the basal body, which anchors the filament to the cell membrane and cell wall and is composed of a series of rings encircling a central, small rod (Gram- positive bacteria have only an inner pair of rings, while Gram- negative bacteria have both inner and outer pairs of rings).

How do microorganisms influence the carbon cycle on Earth?

Most of the organic matter present in soil originates in plant material from leaves, rotting trees, decaying roots, and other tissues. In the carbon cycle, soil bacteria and fungi recycle this carbon by using the organic matter in their metabolism. Without the recycling action of these organisms, life would suffer an irreversible decline as the nutrients essential for life became tied up in complex molecules.

Which microorganisms are involved in the pickling process in food production?

In the pickling process, microorganisms grow and ferment the food in a salty environment while producing large amounts of acid from available carbohydrates. Species of Leuconostoc and Lactobacillus are commonly used in the pickling process. To produce sauerkraut, cabbage is grated and salted and allowed to ferment naturally (since the bacteria are already present among the leaves). For pickled cucumbers, salt is added to fresh cucumbers, and the naturally occurring bacteria ferment the vegetable carbohydrates over a period of weeks. Different spices are added to prepare various forms of sauerkraut and pickled cucumbers.

Do all bacteria require oxygen for growth?

Many bacteria are aerobic; that is, they require oxygen to grow and perform the biochemical reactions of their metabolism. There are, however, a large number of bacterial species that are anaerobic and are cultivated in a special apparatus where the oxygen has been removed. These bacteria (known as anaerobes) live in the absence of oxygen, and they are found in the muddy bottom of swamps, landfills, and soil. Some anaerobes are obligate anaerobes, while others are facultative anaerobes, meaning that they live with or without
oxygen.

Which bacterium is responsible for tuberculosis, and what are the characteristics of the organism?

Tuberculosis is caused by a slender rod known as Mycobacterium tuberculosis. This slow- growing rod is neither Gram- positive nor Gram- negative; rather, it is acid- fast. When stained with carbolfuchsin, steam must be used to force the stain through the bacterial cell wall. Once stained, however, the organism cannot be decolorized even if dilute acid- alcohol is used. This acid- fast characteristic is due to the presence of a very thick cell wall containing mycolic acid.

Why is microbial control necessary and what are some of the factors that go into the choice of a particular antimicrobial agent?

The control of microorganisms is an important way of preventing pathogens from reaching the body.Sterilizing laboratory equipment, hospital supplies, and industrial apparatus helps contain contamination.The choice of a particular antimicrobial agent depends on such things as the kind of material to be treated(living or nonliving), the kind of croorganism to be controlled, the environmental conditions existing at the time of the agent’s use (for example, the temperature of the environment and concentration of microorganisms),
the acidity or alkalinity of the area, and the presence of organic matter.

What is the advantage of the attenuated viruses in a vaccine?

Attenuated viruses can be taken orally because they will survive passage into the gastrointestinal tract and will be absorbed into the blood stream. The method of administration is therefore easier than by injection.However, the drawback is that the viruses may on certain occasion induce mild symptoms of disease in the body and they pose more of a risk than the inactivated viruses. They do call forth a more substantial immune response, however, and for this reason they may be advantageous when an epidemic is taking place or is anticipated.

How is the Gram stain procedure performed in the microbiology laboratory?

In the laboratory, a heat- fixed smear of bacteria is stained with crystal violet for one minute. Then, iodine,which acts as a mordant, is added to the smear for one minute, and the remainder is washed free. All bacteria are now blue- purple. Alcohol decolorizer is added to the slide until the free stain is removed. In this step, the Gram- negative bacteria lose the blue- purple dye, but Gram- positive bacteria retain the dye and remain blue- purple. In the fourth step, the red dye safranin is added to the smear. The Gram- negative bacteria will accept the dye and become red- pink, while the Gram- positive bacteria remain blue- purple. At the conclusion of the procedure, the stains are examined under the microscope and the color of the bacteria reveals the Gram reaction.

Why is tetanus considered a disease of the nervous system?

Tetanus is a disease caused by a Gram- positive, spore- forming anaerobic rod called Clostridium tetani.This organism often exists in the spore form in the human and animal intestine and passes to the soil inthe feces. Tetanus is usually acquired by puncture of the skin from a wound with a piece of glass or other pointed object. The etiological agent grows in the dead tissue and produces a number of toxins, which have their effect on this tissue. These toxins prevent the destruction of acetylcholine in the synapse and encourage nerve impulses to pass into the muscles, where they cause continual muscle contractions symptomatic of tetanus. Since the primary effect is in the nervous system, tetanus is considered a disease of this
system.