1.A. Penicillins are β-lactam antibiotics in structure. The remodeling process takes place in the bacterial cell walls due to the presence of a layer called peptidoglycan layer, which includes the breakdown of β-(1,4) linked N-acetylmuramic acid and N-acetylglucosamine and cross-linking peptide chains . Cross-linking peptide chains provide rigidity to the fluid cell wall. Transpeptidase, an enzyme used in the breaking of peptide chains also reforms the peptide bonds after the restructuring of the cell wall. The penicillin inhibits the enzyme transpeptidase, which prevents the peptide bonds from reforming. Thus, penicillin makes the cell walls weaker, which results the bacteria to leak out its cellular components and die.
1.B. Penicillin kills the bacteria by weakening its cell walls for which it targets the enzyme that cross-link the peptidoglycan layer . Penicillin has a beta-lactam ring in its structure. The bacteria resist to penicillin secrete beta-lactmases, which cleave the beta-lactam ring of penicillin molecule making the drug inactive. Another mechanism is to target the molecules and enzymes that cross-link peptidoglycan. The third mechanism is to restrict the transport of penicillin to the cell wall.
1.C. The chemical strategies to overcome penicillin resistance include the development of resistance enzyme inhibitors and change in pencillin-binding proteins. Chemical strategies are refractory in nature to known resistance mechanisms. Combining the β-lactam with either aminoglycoside or tetracycline helps to reduce resistance and proves to be a success in treating several types of diseases. The use of clavulanic acid and its related compounds, which inhibit β-lactamase enzymes is another chemical strategy in overcoming penicillin resistance .
1.D. Phages are viruses, which intrude bacterial cells and result in their destruction by the disruption of bacterial metabolism. The limitations of phages are metabolic destruction of molecules, need of antibiotics to kill the bacteria and resistance of bacteria to different types of antibiotics.
1.E. The habitation of human genes and genes of bacteria and viruses, which occupy the mucus membranes, skin and intestinal tract form the microbiome. There is a link between human microbiome, disruption of diurnal rhythm and obesity. Intestinal microbiome are responsible for obesity, while the gut microbiome are the cause for the disruption of diurnal rhythm .
2.A. HIV treatment modalities depend on certain factors, such as past history, CD4 T cell count, current health and length of time infected by HIV. Preventive and therapeutic vaccines are under the test phase. Antiretroviral therapies slow down the development of infection in HIV patients. Doctors administer certain antibiotics depending upon the health of the patients and examine the occurrence of side effects. Each HIV particle contains two copies of HIV RNA with 2000 copies of p24 viral protein particles, which clusters with the CD4+ cells . In certain circumstances, HIV is stable at room temperature. The survival and stability of HIV infection outside the body depends on various factors, such as body fluid, volume of fluid, concentration of virus, exposure to humidity, sunlight and temperature.
2.B. As soon as the virus enters the human body, it attaches to the cells of the immune system called dendritic cells, which are present in the mucosal membranes of the body. HIV infection infects multiple cells in the human body, such as penis, vagina, rectum, upper gastrointestinal tract, mouth, including the brain cells; however, the main target cells are the CD4 lymphocyte, also called as the T-cell or CD4 cell and macrophages .
2.C. HIV latency is a state of asymptomatic period between the initial contagion of the virus and the progress of AIDS. HIV latency acts as a barrier in the cure of the disease because latency infected cells restart new rounds of viral replication with the halt of the treatment. Though anti-latency drugs deal effectively with the latency infected cells, they are not safe for longer periods due to their toxic effects.
2.D. bNAb or broad neutralizing antibody is an antibody, which neutralizes the biological effect of an antigen to defend the cells of the body. Even without the production of white blood cells, bNab can fight against the viruses that attack the immune system. Though the first HIV bNab saw its discovery in the year 1990, scientists were not able to establish a perfect relation between bNab and HIV infection until 2006. In the year 2006, scientists analyzed the blood samples of 1800 HIV infected patients and probed 30000 B-cells capable of producing antibodies out of which two bNabs were able to stop around 70 percent of HIV strains from progressing infection .
2.E. bNab has the potential to block the replication of HIV infection as the antibodies pressurize the immune system on specific viruses that lead to escape. bNAbs hold the cell-free viruses and block the virion from targeting the host cells, thereby interrupting the replication of infection .
3.A. HIV patients have higher cancer risk due to their weak immune system as a consequence of HIV infection. The immune system of HIV patients is unable to defend against infections that cause various cancers. The other reasons that increase the risk of cancer in addition to an impaired immune system are dysregulation of cytokine pathways and stimulation of chronic B cells .
3.B. In HIV- patients, Kaposi’s sarcoma is a rare cancer type and occurs in elders or those who take immunosuppressant post organ transplantation . However, in HIV+ patients, the risk of Kaposi's sarcoma is 100 to 300 times more. In HIV- patients, the classic or endemic type of Kaposi's sarcoma is visible in common, while in HIV+ patients, the other two types, namely, iatrogenic and epidemic are also common in addition to classic and endemic types .
Lung cancer is another cancer type that shows different behaviors in HIV+ and HIV- patients. The risk of occurrence of lung cancer is high in HIV+ patients, and higher in those who smoke . There is a positive correlation between immune suppression and the rate of lung cancer. The chances of survival are higher in HIV- patients when compared to HIV+ patients because in HIV+ patients, lung cancer occurs at a very earlier age of the occurrence of HIV infection and increases the risk with the increase in HIV infection. In HIV- patients, it is possible to slow down the growth lung cancer through medical treatments, which is least effective in HIV+ patients.
3.C. The treatment of cancer in HIV patients is much similar to those without HIV infection. The treatment for cancer depends upon the stage or extent and the type of the cancer. The treatment includes the administration of anti-HIV drugs in addition to standard cancer treatment therapies. Simultaneously, the treatment also includes the administration of antibiotics to treat HIV infections . In HIV patients, there is a high possibility that the anti-HIV drugs interfere with the cancer treatment as they interact with other drugs. Some anti-HIV drugs cause side effects, which are similar to those caused by cancer treatment or chemotherapy. Also, people suffering from HIV have low success rates of overcoming certain types of cancer due to the weak immune system and several other factors.
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Feigal, Ellen G., Alexandra M. Levine and Robert J. Biggar. AIDS-Related Cancers and Their Treatment. CRC Press, 2000.