By Z. Fadi. Spertus College.
For example cheap bactroban 5 gm on line acne home treatments, oxygen buy 5 gm bactroban free shipping acne 5 days before period, with six electrons in its valence shell, is likely to react with other atoms in a way that results in the addition of two electrons to oxygen’s valence shell, bringing the number to eight. When two hydrogen atoms each share their single electron with oxygen, covalent bonds are formed, resulting in a molecule of water, H O. In so doing, the two elements form the simplest of organic molecules, methane, which also is one of the most abundant and stable carbon-containing compounds on Earth. Incidentally, the name “hydrogen” reflects its contribution to water (hydro- =2 “water”; -gen = “maker”). Most physicists would say no, because the negatively charged electrons in their valence shells repel one another. No force within the human body—or anywhere in the natural world—is strong enough to overcome this electrical repulsion. So when you read about atoms linking together or colliding, bear in mind that the atoms are not merging in a physical sense. The new grouping is typically more stable—less likely to react again—than its component atoms were when they were separate. A more or less stable grouping of two or more atoms held together by chemical bonds is called a molecule. The bonded atoms may be of the same element, as in the case of H , which is called molecular hydrogen or hydrogen gas. Ions and Ionic Bonds Recall that an atom typically has the same number of positively charged protons and negatively charged electrons. But when an atom participates in a chemical reaction that results in the donation or acceptance of one or more electrons, the atom will then become positively or negatively charged. This happens frequently for most atoms in order to have a full valence shell, as described previously. This can happen either by gaining electrons to fill a shell that is more than half-full, or by giving away electrons to empty a shell than is less than half-full, thereby leaving the next smaller electron shell as the new, full, valence shell. What happens to the charged electroscope when a conductor is moved between its plastic sheets, and why? This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. Water is an essential component of life because it is able to break the ionic bonds in salts to free the ions. The electrical activity that derives from the interactions of the charged ions is why they are also called electrolytes. Covalent Bonds Unlike ionic bonds formed by the attraction between a cation’s positive charge and an anion’s negative charge, molecules formed by a covalent bond share electrons in a mutually stabilizing relationship. Like next-door neighbors whose kids hang out first at one home and then at the other, the atoms do not lose or gain electrons permanently. Instead, the electrons move 52 Chapter 2 | The Chemical Level of Organization back and forth between the elements. Because of the close sharing of pairs of electrons (one electron from each of two atoms), covalent bonds are stronger than ionic bonds. Notice that the two covalently bonded atoms typically share just one or two electron pairs, though larger sharings are possible. The important concept to take from this is that in covalent bonds, electrons in the outermost valence shell are shared to fill the valence shells of both atoms, ultimately stabilizing both of the atoms involved. In a single covalent bond, a single electron is shared between two atoms, while in a double covalent bond, two pairs of electrons are shared between two atoms. The sharing of the negative electrons is relatively equal, as is the electrical pull of the positive protons in the nucleus of the atoms involved. This is why covalently bonded molecules that are electrically balanced in this way are described as nonpolar; that is, no region of the molecule is either more positive or more negative than any other.
This concept was introduced into Europe in the early 18 century bactroban 5 gm on line acne jeans review, and in 1796 purchase 5 gm bactroban otc skin care face, Edward Jenner did his first human experiments using cowpox to vac- cinate (vacca is Latin for cow) against smallpox. Greater advances were made in vacci- nology and immunology, and vaccines became safer and mass-produced. Today, thanks to the advances of molecular technology, we are on the verge of making influenza vaccines through the genetic manipulation of influenza genes (Couch 1997, Hilleman 2002). Yearly Vaccine Production All vaccines in general use today are derived from viruses grown in hens’ eggs, and contain 15 µg of antigen from each of the three strains selected for that year’s vac- cine – two influenza A strains (H1N1 and H3N2) and one influenza B strain. From 128 Vaccines the selection of the strains to be used in the vaccine, all the way to the final vaccine, is a lengthy process that may take up to 6–8 months. This decision is made each year in February for the following northern hemisphere winter and September for the following southern hemisphere winter. One can see that the H1N1 influenza A in the vaccine still represents the circulating strain, while the H3N2 virus has changed over time. As a matter of fact, the rate of vaccine failure was unusually high during the winter season 2004/2005. If the strain Vaccine Development 129 chosen to be represented in the vaccine is the same as that used in the previous vac- cine, the process is faster. This new virus is then incubated in embryonated hens’ eggs for 2-3 days, after which the allantoic fluid is harvested, and the virus particles are centrifuged in a solution of increasing density to concentrate and purify them at a specific density. Finally, the concentrations are standardized by the amount of hemagglutination that occurs (Hilleman 2002, Potter 2004, Treanor 2004). After this, the three strains – two influenza A strains and one influenza B strain, which were all pro- duced separately – are combined into one vaccine, their content verified, and packaged into syringes for distribution. Production capacity At present, the world has a production capacity of about 300 million trivalent influ- enza vaccines per year, most of which is produced in nine countries – Australia, Canada, France, Germany, Italy, Japan, the Netherlands, the United Kingdom, and the United States. Types of Influenza Vaccine The different types of vaccines in use today for influenza can be divided into killed virus vaccines and live virus vaccines. Other vaccines of these two types are under development, as well as some that do not fall into either category, where a degree of genetic manipulation is involved. Killed vaccines Killed virus vaccines can be divided into whole virus vaccines, and split or subunit vaccines. The influenza virus was grown in the allantoic sac of embryonated hens’ eggs, subsequently purified and concen- trated using red blood cells, and finally, inactivated using formaldehyde or β- propiolactone. Later, this method of purification and concentration was replaced with centrifuge purification, and then by density gradient centrifugation, where vi- rus particles of a specific density precipitate at a certain level in a solution of in- creasing density. Subsequently, filter-membrane purification was added to the methods available for purification/concentration (Hilleman 2002, Potter 2004). Split and subunit vaccines cause fewer local reactions than whole virus vaccines, and a single dose produces adequate antibody levels in a population exposed to similar viruses (Couch 1997, Hilleman 2002, Potter 2004). However, this might not be sufficient if a novel pandemic influenza virus emerges, and it is believed that two doses will be required. Inactivated influenza virus vaccines are generally administered intramuscu- larly, although intradermal (Belshe 2004, Cooper 2004, Kenney 2004) and intranasal (mucosal) routes (Langley 2005) are being investigated. The master viruses used are A/Ann Arbor/6/60 (H2N2) and B/Ann Arbor/1/66 (Hoffman 2005, Palese 1997, Potter 2004). The vaccine master virus is cold-adapted – in other words, it has been adapted to grow ideally at 25 degrees Celsius, which means that at normal human body temperature, it is at- tenuated. The advantages of a live virus vaccine applied to the nasal mucosa are the devel- opment of local neutralising immunity, the development of a cell-mediated immune response, and a cross-reactive and longer lasting immune response (Couch 1997). Damage to mucosal surfaces, while far less than with wild-type virulent influenza viruses, may lead to susceptibility to secondary infections. Of greater concern for the future is the possibility of genetic reversion – where the mutations causing attenuation change back to their wild-type state – and reassortment with wild-type influenza viruses, resulting in a new strain. However, setting up such a facility takes time and is costly, and most vaccine producers are only now beginning this process.
Provides greater herd immunity-spreads to immunize contact of the vaccine Is easier to administer and less expensive At least three doses are required in primary immunization to establish protection against the 3 poliomyelitis serotypes 1 discount 5gm bactroban with amex -,2 bactroban 5gm generic acne holes in face,3. Measles Vaccines: Natural measles infection is a serious disease with greater risk of morbidity and mortality than the vaccine. Measles vaccine: Early vaccination produces a poor response in some children because of maternal antibody still in the child’s circulation. Measles is given at 6-9 months in measles endemic areas; and after 12 months elsewhere. Children immunized before 12 months need a second dose after 14 months of age to ensure individual protection 172 Pediatric Nursing and child health care Indication for measles vaccination: • All children in measles endemic area • To interrupt a measles outbreak • the incubation period for the vaccine is shorter than that of the natural disease • measles vaccine given within days of contact stops the spread of the disease Contraindication to measles vaccine: • Sensitivity to vaccine content (e. The six vaccine preventable diseases are estimated to account for at least one-third of infant and child disability and mortality. Often mothers bring their children at less frequent intervals than those suggested here. If the child is first seen at a later stage than indicated in the immunization scheme, the immunization is started with vaccines 1,2,3 and 4, given with four weeks interval. Reusable needles and syringes should be sterilized correctly (steam sterilization or boiling for 20 minutes) 2. What are the dangers of using contaminated syringes and needles during vaccination and what are the steps to be used to prevent it? The vaccine preventable diseases estimated to account for one third of infant and child disability and mortality in Ethiopia. Mental Retardation: If a child is significantly retarded in his psychomotor development (milestones) we suspect subnormal intelligence and speak of mental retardation. In very mild case there may be only minimal brain damage giving rise to slight delay only and less than optimal intelligence may only become obvious in school. He can not sit without support at age 9 months, can not stand at at age 15 months, can not walk at age 18 months b. He can not lough loudly at age 6 months, speak three words at age 2 years, and follow a few simple directions at age 3 years c. He can not grasp actively at age 6 months, and take small objects with thumb and finger at age 1 year. Inherited abnormalities or subnormalities of the brain like in microcephalus, hydrocephalus. An abnormality of chromosomes the carrier of inheritance in the cellular nucleus the feature of mongolism (Down’s syndrome) characteristic faces with slanting eyes, a small flat nose a protruding tongue, low set ears and small head. Perinatal problems (prematurity, asphyxia) , or disease acquired after the neonatal period (meningitis, encephalitis, cerebral malaria) may damage the brain d. Deafness can mimic mental retardation 182 Pediatric Nursing and child health care Management: Since there is no treatment of the cause 1. In moderate retardation habit training – eating, walking, and putting on cloths 2. In mild retardation special attention in schools or ideally special school can of value 3. It is a term used for all permanent, no-progressive, generalized brain damage in children irrespective of the cause. Usually some degree of spasticity symptoms are combined with mental retardation, but sometimes the mental retardation is minimal or even abscent. Prenatal: acquired disease such as congenital infection Perinatal: (shortly before or after delivery) : asphyxia, cerebral hemorrhage, b. After the first week of life: meningitis, encephalitis, cerebral malaria can also cause cerebral palsy 183 Pediatric Nursing and child health care Clinical Features: 1. Spastic paralysis if the lesion unilateral or spastic paraplegia if the lesion bilateral 2. Regular exercise under the guidance of physiotherapist help in preventing deformity and contracture 2. Parents of such children support and reassurance Prevention: • Proper antenatal and perinatal care, • early recognition of meningitis etc 13. Down’s Syndrome: Down’s syndrome is a chromosomal abnormality involving an extra chromosome (number 21) characterized by a typical physical appearance and mental handicap. Abnormal attachment of chrosomes inherited from parents 184 Pediatric Nursing and child health care Clinical Manifestations: 1. If diagnosed within the first month of life and substitution with thyroid hormone continued regularly the child will have a normal life 3.
The vitamin B12 synthesized by microbes is deposited in animal tissues generic 5 gm bactroban with mastercard skin care malaysia, such as liver discount 5gm bactroban visa skin care 5-8 years, eggs, and 263 Hematology milk, and is therefore plentiful in fish and meat products. The average diet contains 5 to 30µg of vitamin B12 daily, 1 to 2µg of which usually is absorbed and retained. In the adult a storage pool of 3000 to 5000µg is present, of which 1000 to 3000µg is stored in the liver. If malabsorption of vitamin B12 occurs, it will take 2 to 5 years before body stores are exhausted and megaloblastic erythropoiesis supervenes. Normal subjects will excrete in their urine 7 percent or more of the radioactivity taken orally, whereas patients with pernicious anemia or other causes of vitamin B12 malabsorption will excrete well less than 7 percent. In part three of the Schilling test a 2-week course of antibiotic therapy with tetracycline, 250mg four times per day, is prescribed. If bacterial overgrowth was responsible for the abnormal second part of the Schilling test, then tetracycline treatment should normalize vitamin B12 absorption. Much less commonly the deficiency may be caused by veganism in which the diet lacks B12 (usually in Hindu Indians), gastrectomy or small intestinal lesions. There is no syndrome of B12 deficiency due to increased utilization or loss of the vitamin, so the deficiency inevitably takes at least 2 years to develop, i. Folic acid The terms folic acid and folate refer to a large group of compounds consisting of three moieties, pteridine, para- aminobenzoic acid, and a variable number of glutamic acid units. Folates are widely distributed in a variety of food, including green vegetables, liver, kidney, and dairy products (Table 17. During the process of intestinal absorption the folates are converted to 5-methyltetrahydrofolate, which is the main transport and storage for of folate in man. For this reason it takes 3 to 6 months for 269 Hematology tissue stores to be completely exhausted in the absence of folate replacement. Folate deficiency is most often due to a poor dietary intake of folate alone or in combination with a condition of increased folate utilization or malabsorption (Table 17. Excess cell turnover of any sort, including pregnancy, is the main cause of an increased need for folate. Aplastic Anemia Aplastic (hypoplastic) anemia is defined as pancytopenia (anemia, leucopenia, and thrombocytopenia) resulting from aplasia of the bone marrow. Patients with aplastic anemia generally have symptoms characteristic of a particular cellular deficiency. Those with anemia may be fatigued or short of breath, those with neutropenia may manifest serious infection, and those with thrombocytopenia may demonstrate petechiae or bleeding. A low reticulocyte count suggests underproduction rather than increased loss or destruction of red cells. The diagnosis is confirmed with a bone marrow biopsy that shows a substantial decrease in the number of red cell, white cell, and platelet precursors, and replacement of the usually cellular bone marrow with fat. Aplastic anemia can be mild or severe, and the 272 Hematology management of the patient depends on the severity of the illness. Failure of the pluripotential stem cells of the bone marrow to maintain bone marrow cellularity and the production of normal numbers of mature red cells, neutrophils, and platelets characterizes aplastic anemia. Many agents that cause aplastic anemia, such as benzene and radiation, can on occasion precipitate malignant transformation of the damaged bone marrow stem cells, resulting in the development of acute leukemia. Pure Red cell Aplasia Acquired pure red cell aplasia is a rare disorder, usually immunologically mediated, in which there is a specific failure of production of red cells. The bone marrow biopsy shows a selective absence of red blood cell precursors, whereas white cell and platelet precursors are present in normal numbers. The primary cause of the anemia is a lack of erythropoietin, a hormone necessary for red cell growth and development in the bone marrow. About 40 percent of the time, the anemia is microcytic and hypochromic, usually only mildly so, but occasionally sufficient to cause confusion with iron deficiency anemia. Inspection of the bone marrow usually shows abundant iron in reticuloendothelial cells, but little or no iron in red cell precursors. Thus, the patient has adequate iron stores, but is unable to transfer iron from the reticuloendothelial system storage cells to the red cell precursors that need it to form hemoglobin. The cause of this block in iron reutilization is uncertain, and there is no effective treatment other than to correct the 276 Hematology underlying chronic disease.