Hepatitis B Virus Essay Example | Topics and Well Written Essays - 1000 words

Hepatitis B Virus - Essay Example The complete infective virion is a 42nm particle comprising an inner core of 27 nm surrounded by an outer envelope of surface protein HBsAg. This surface coat is produced in excess by the infected hepatocytes and can exist separately form the whole virion in the serum and the body as 22nm particle. The genome of HBV is a partially double stranded circular DNA molecule with a unique In that all regions of the viral genome encode protein sequences. HBsAG contains a major â€Å"a† antigenic determinant as well as several subtypes: â€Å"d† â€Å"y† â€Å"w† and â€Å"r†. Combinations of these sub-determinants ( e:g adr, adw, ayw, and ayr) are used to classify HBV genotypes A-H of which the main types are type A(35%) B(225) (31%) and D(10%). There is a strong correlation between genotypes and geographical areas. Genotype A is mainly seen in North west Europe, North America, North America and central Africa; B in south East Asia; C in south East Asia D; in southern Europe, India and the middle East; E in west Africa; F in south and central America, in American Indians and in Polynesia. G in France and the USA; and H in central and south America. The core is formed of core protein (HBcAg) containing incompletely double stranded circular DNA and DNA polymerase/reverse transcriptase. One strand is almost a complete circle and contains overlapping genes that encode both structural proteins (pre-S, surface (s), core (s)) and replicative proteins (polymerase and x). The other strand is variable in length synthesis during the viral replication. If there is an acute clinical episode the virus is cleared in approximately 90% of patients as there is a good immune reaction. There is serum sickness-like immunological syndrome see urticaria or maculopapular rash and polyathritis affecting small joints and occurring in up to 25% of case in the subclinical period. There is increase of temperature. Extrahepatic immune

Space and Place Assignment Example | Topics and Well Written Essays - 500 words - 1

Space and Place - Assignment Example However, the visit was different as we had to travel to China for the amazing experience. I was excited about this trip as it would give me an opportunity to experience a skywalk or a glass trail that was elevated at four thousand seven hundred feet above sea level. I had imagined a similar experience to that of the Grand Canyon skywalk, but the walk on the glass trail was fascinating, breathtaking and frightening at the same time. Every step that I took on the breathtaking glass walkway reminded me that my life was held by three inches of glass suspended over hundreds of metres from the bottom of the mountain. This trail was unique in that it excited and scared me, therefore, captivated all my senses at the same time. It is one of the greatest places that I have ever visited and it created a lasting impression on my mind. The glass trail is located high on the Tianmen Mountain in the Hunan province of mainland China. The area is famous with tourists for its beautiful national parks, mountain sceneries, the Chinese culture and a wide range of animal and plant species. In order to access the glass walkway, one has to use cable cars provided at the bottom of the mountain. Tianmen Mountain has the longest passenger cableway that allows the rider to get a clear complete view of the beautiful landscape, valleys and the vegetation around the area. The high elevation of the mountain leaves a lasting impression on an individual’s mind as one travels in the cable car (Darrall). The two hundred feet glass walkway is built on a cliff on the Tianmen Mountain. It is three feet wide and has a steel rail on the open side protecting the site observers from toppling over. Watching the view of the landscape from the skywalk is breathtaking as it provides a different panorama of the mountain. It provides a clear view of the moist, misty landscape. The roads, the rivers and other physical features seem minute from this view and