The structural integrity of bacterial cell wall depends on the cross linking of UDP-MurNAc and N-acetyl glucosamine. Penicillin and other β-lactam antibiotics act as an analogue of D-alanine-D-alanine (the dipeptide) in UDP-MurNAc owing to conformational similarities. The DD-transpeptidase then binds the four-membered β-lactam ring of penicillin instead of UDP-MurNAc. As a consequence, DD-transpeptidase is inactivated, the formation of cross-links between UDP-MurNAc and N-acetyl glucosamine is blocked so that an imbalance between cell wall production and degradation develops, causing the cell to rapidly die.The enzymes that hydrolyze the peptidoglycan cross-links continue to function, even while those that form such cross-links do not. This weakens the cell wall of the bacterium, and osmotic pressure becomes increasingly uncompensated—eventually causing cell death (cytolysis). In addition, the build-up of peptidoglycan precursors triggers the activation of bacterial cell wall hydrolases and autolysins, which further digest the cell walls peptidoglycans. The small size of the penicillins increases their potency, by allowing them to penetrate the entire depth of the cell wall. This is in contrast to the glycopeptide antibiotics vancomycin and teicoplanin, which are both much larger than the penicillins.Gram-positive bacteria are called protoplasts when they lose their cell walls. Gram-negative bacteria do not lose their cell walls completely and are called spheroplasts after treatment with penicillin.Penicillin shows a synergistic effect with aminoglycosides, since the inhibition of peptidoglycan synthesis allows aminoglycosides to penetrate the bacterial cell wall more easily, allowing their disruption of bacterial protein synthesis within the cell.
Pyromania moved from the DSM-4 chapter "Impulse-Control Disorders Not Otherwise Specified," to the chapter "Disruptive, impulse-control, and conduct disorders" in DSM-5. Signs and symptoms
According to DSM-5, there are six signs of pyromania. Pyromania is mainly categorized by the purposeful setting of fire, tension or arousal before a fire is set, interest in or attraction to fire, and pleasure or relief after setting a fire. These fires not set for personal gain, are not meant to express anger or conceal illegal activity, are not in support of sociopolitical ideologies, are not in response to delusions, and are not signs of intellectual disability. For diagnosis, the setting of fire should not be better explained by a conduct disorder, manic episode, or a personality disorder (antisocial personality disorder). ICD-11 also adds substance abuse to this list. According to ICD-11, signs of fire setting may occur "in response to feelings of depressed mood, anxiety, boredom, loneliness, or other negative affective states." Those with pyromania exhibit problems in social environments and learning disabilities. Women pyromaniacs "often report histories of exposure to trauma, including sexual abuse, and self-harm." Episodic fire setting may become more intense and violent over time, becoming potentially chronic if untreated. Causes
Most studied cases of pyromania occur in children and teenagers. There is a range of causes, but an understanding of the different motives and actions of fire setters can provide a platform for prevention. Common causes of pyromania can be broken down into two main groups: individual and environmental.