Drugs online research references
Eur J Biochem. 1975 Jul 1;55(2):465-73.
D-alanyl-D-alanine carboxypeptidase in the bacterial form and L-form of Proteus mirabilis.
Martin HH, Maskos C, Burger R.
Membranes of the bacterial form and the stable and unstable L-forms of Proteus mirabilis contain LD and DD-carboxypeptidase. The DD-carboxypeptidase is inhibited non-competitively by penicillin G. The enzyme of the bacterial form is highly penicillin-sensitive (Ki - 4 X 10(-9) M penicillin G). Inhibition is only partly reversible by treatment with penicillinase or by dialysis against buffer. In contrast, the DD-carboxypeptidase of the unstable L-form, grown in the presence of penicillin, is 175-fold less penicillin-sensitive (Ki = 7 X 10(7) M penicillin G). Inhibition is completely reversed by penicillinase or dialysis. After inhibition by penicillin and subsequent reactivation the penicillin sensitivity of the bacterial DD-carboxtpeptidase is similar to the sensitivity of the enzyme of the unstable L-form. The hypothesis is proposed that P. mirabilis contains two DD-carboxypeptidases of different penicillin sensitivity and with different mechanisms of penicillin binding. Peptidoglycan synthesis in the cell walls of the unstable L-form is probably carried out with the help of only one DD-carboxypeptidase, viz. the completely reactivatable enzyme with the lower penicillin sensitivity.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=238&dopt=Abstract
Fundam Appl Toxicol. 1989 Feb;12(2):252-7.
Two-year toxicity and carcinogenicity studies of ampicillin trihydrate and penicillin VK in rodents.
Dunnick JK, Eustis SL, Huff JE, Haseman JK.
National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Toxicology and carcinogenesis studies of ampicillin trihydrate and penicillin VK, two widely used beta-lactam antibiotics, were performed in F344/N rats and B6C3F1 mice. In these studies ampicillin trihydrate was administered for 2 years to rats at doses of 0, 750, or 1500 mg/kg and to mice at doses of 0, 1500, or 3000 mg/kg, and penicillin VK was administered to rats and mice at doses of 0, 500, or 1000 mg/kg. Both drugs were administered by oral gavage in corn oil. Toxic lesions of the stomach were seen in rats and mice after ampicillin trihydrate administration and in mice after penicillin VK administration. In male rats that received ampicillin trihydrate there was a marginal increase in incidence of mononuclear cell leukemia and pheochromocytomas of the adrenal gland medulla. There was no evidence for carcinogenic activity in female rats or male and female mice after ampicillin trihydrate administration or in rats and mice after penicillin VK administration.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2497039&dopt=Abstract
BMJ. 1989 Apr 1;298(6677):856-9.
Untreated asymptomatic bacteriuria in girls: II--Effect of phenoxymethylpenicillin and erythromycin given for intercurrent infections.
Hansson S, Jodal U, Lincoln K, Svanborg-Eden C.
Department of Paediatrics, Gothenburg University, East Hospital, Sweden.
OBJECTIVE--To investigate the effects of phenoxymethylpenicillin and erythromycin on urinary isolates from patients with untreated asymptomatic bacteriuria. DESIGN--Retrospective study of subgroup of patients from cohort followed up till the end of 1986. SETTING--Outpatient clinic for children with urinary tract infections. PATIENTS--51 Girls aged under 15 with untreated asymptomatic bacteriuria. INTERVENTIONS--Before 1982 intercurrent infections (mostly tonsillitis or otitis) were treated with phenoxymethylpenicillin; after 1982 erythromycin treatment was preferred. END POINTS--Change of bacterial strain in urinary tract and symptomatic recurrences of disease. MEASUREMENTS AND MAIN RESULTS--Bacteria identified by serotype and electrophoretic type and compared before and after antibiotic treatment. Bacteriuria eradicated and replaced by new strains in most patients treated with phenoxymethylpenicillin, leading to symptomatic recurrences in about 15%. Conversely, patients given erythromycin rarely showed change in bacteriuria and none suffered symptomatic recurrence. CONCLUSIONS--In girls with untreated asymptomatic bacteriuria the use of phenoxymethylpenicillin for intercurrent infections may lead to a change of urinary bacteria and leave them at substantial risk of acute pyelonephritis. With erythromycin this risk is small (2/20 courses in this series).
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2497823&dopt=Abstract
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