Non-lead alternatives include copper, zinc, steel, tungsten-nickel-iron, bismuth-tin, and polymer blends such as tungsten-polymer and copper-polymer. Because game animals can be shot using lead bullets, the potential for lead ingestion from game meat consumption has been studied clinically and epidemiologically. In a recent study conducted by the CDC, a cohort from North Dakota was enrolled and asked to self-report historical consumption of game meat, and participation in other activities that could cause lead exposure. The study found that participants age, sex, housing age, current hobbies with potential for lead exposure, and game consumption were all associated with blood lead level (PbB). According to a study published in 2008, 1.1% of the 736 persons consuming wild game meat tested had PbB ≥5 μg/dl In November 2015 The US HHS/CDC/NIOSH designated 5 µg/dL (five micrograms per deciliter) of whole blood, in a venous blood sample, as the reference blood lead level for adults. An elevated BLL is defined as a BLL ≥5 µg/dL. This case definition is used by the ABLES program, the Council of State and Territorial Epidemiologists (CSTE), and CDCs National Notifiable Diseases Surveillance System (NNDSS). Previously (i.e. from 2009 until November 2015), the case definition for an elevated BLL was a BLL ≥10 µg/dL. To virtually eliminate the potential for lead contamination, some researchers have suggested the use of lead-free copper non-fragmenting bullets.Bismuth is an element used as a lead-replacement for shotgun pellets used in waterfowl hunting although shotshells made from bismuth are nearly ten times the cost of lead.
Psychiatry
A 2015 Cochrane review found no evidence of benefit in anxiety disorders as of 2015. Another review found preliminary evidence of benefit. Evidence for use in addiction is tentative but also unclear. Mechanism of action
Cycloserine works as an antibiotic by inhibiting cell-wall biosynthesis in bacteria. As a cyclic analogue of D-alanine, cycloserine acts against two crucial enzymes important in the cytosolic stages of peptidoglycan synthesis: alanine racemase (Alr) and D-alanine:D-alanine ligase (Ddl). The first enzyme is a pyridoxal 5-phosphate-dependent enzyme which converts the L-alanine to the D-alanine form. The second enzyme is involved in joining two of these D-alanine residues together by catalyzing the formation of the ATP-dependent D-alanine-D-alanine dipeptide bond between the resulting D-alanine molecules. If both of these enzymes are inhibited, then D-alanine residues cannot form and previously formed D-alanine molecules cannot be joined together. This effectively leads to inhibition of peptidoglycan synthesis. Chemical properties
Under mildly acidic conditions, cycloserine hydrolyzes to give hydroxylamine and D-serine. Cycloserine can be conceptualized as a cyclized version of serine, with an oxidative loss of dihydrogen to form the nitrogen-oxygen bond.Cycloserine is stable under basic conditions, with the greatest stability at pH = 11.5. History
The compound was first isolated nearly simultaneously by two teams. Workers at Merck isolated the compound, which they called oxamycin, from a species of Streptomyces. The same team prepared the molecule synthetically. Workers at Eli Lilly isolated the compound from strains of Streptomyces orchidaceus. It was shown to hydrolyze to serine and hydroxylamine.