Synthesis, herbicidal activity, and mode of action of IR 5790.

IR 5790, an arylthiadiazolone herbicide structurally related to oxadiargyl and oxadiazon, was synthesized. The herbicidal activity and mode of action of IR 5790 were investigated. This herbicide has broad-spectrum pre-emergence activity against both dicotyledonous and monocotyledonous weeds. The phenotypic responses of susceptible plants, such as interruption of growth and light-dependent development of necrotic areas on the foliage, are consistent with those observed with protoporphyrinogen oxidase-inhibiting herbicides. Tissues exposed to IR 5790 in darkness accumulated protoporphyrin IX, which led to a photodynamic loss of membrane integrity upon exposure to light. Consistent with these physiological symptoms, IR 5790 strongly inhibited protoporphyrinogen oxidase, with an I(50) value of 3 nM. The presence of a sulfur atom did not significantly alter the molecular properties of the thiadiazolone ring, relative to the oxadiazolone ring of oxadiargyl, which explains why IR 5790 has the same mode of action as this herbicide.

The phytotoxic lichen metabolite, usnic acid, is a potent inhibitor of plant p-hydroxyphenylpyruvate dioxygenase.

The lichen secondary metabolite usnic acid exists as a (-) and a (+) enantiomer, indicating a alpha or beta projection of the methyl group at position 9b, respectively. (-)-Usnic caused a dose-dependent bleaching of the cotyledonary tissues associated with a decrease of both chlorophylls and carotenoids in treated plants whereas no bleaching was observed with the (+) enantiomer. (-)-Usnic acid inhibited protophorphyrinogen oxidase activity (I50 = 3 microM), but did not lead to protoporphyrin IX accumulation. Bleaching appears to be caused by irreversible inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase by (-)-usnic acid (apparent IC50 = 50 nM).

Trimethoprim-sulfamethoxazole-induced aseptic meningitis: case report and literature review.

Aseptic meningitis is a rare adverse drug reaction, reported with non-steroidal anti-inflammatory agents (NSAIDs) and with miscellaneous drugs such as trimethoprim-sulfamethoxazole (TMP-SMX). The most common clinical findings reported are fever, headache, stiffness and altered level of consciousness. We report a case of aseptic meningitis related to TMP-SMX ingestion that caused severe derangements of the patient's vital signs, requiring Intensive Care Unit admittance. The prompt diagnosis and discontinuation of the drug resulted in complete recovery. We examine the case according to the literature on this topic. We conclude that, since the signs and symptoms of this unusual drug reaction may mimic those of central nervous system infection, the clinician should consider this etiology when he is faced with a patient with suspected meningoencephalitis, especially if the latter has already been treated at home with unknown drugs. Further studies should investigate the pathogenetic mechanism of TMP-SMX-induced aseptic meningitis.

[A case of severe posterior hepatic lesion caused by contusion trauma]. / Un caso di grave lesione epatica posteriore da trauma contusivo.

A case of blunt liver trauma with massive peritoneal hemorrhage due to a major intraparenchymal injury with active bleeding from a posterior tributary of the right hepatic vein is reported. The treatment consisted of resectional debridement of the VII and VI segment of Couinaud and hemostasis was possible in total vascular exclusion without an intracaval shunt.