Inhibitory effects of a Kunitz-type inhibitor from Pithecellobium dumosum (Benth) seeds against insect-pests' digestive proteinases.

Pithecellobium dumosum is a tree belonging to the Mimosoideae subfamily that presents various previously characterized Kunitz-type inhibitors. The present study provides a novel Kunitz-trypsin inhibitor isoform purified from P. dumosum seeds. Purification procedure was performed by TCA precipitation followed by a trypsin-Sepharose chromatography and a further reversed-phase HPLC. Purified inhibitor (PdKI-4) showed enhanced inhibitory activity against bovine trypsin and chymotrypsin. Furthermore, PdKI-4 showed remarkable inhibitory activity against serine proteases from the coleopterans Callosobruchus maculatus and Zabrotes subfasciatus, and the lepidopterans Alabama argillacea and Telchin licus. However, PdKI-4 was unable to inhibit porcine pancreatic elastase, pineapple bromelain and Carica papaya papain. SDS-PAGE showed that PdKI-4 consisted of a single polypeptide chain with molecular mass of 21 kDa. Kinetic studies demonstrated that PdKI-4 is probably a competitive inhibitor with a Ki value of 5.7 × 10(-10) M for bovine trypsin. PdKI-4 also showed higher stability over a wide range of temperature (37-100 °C) and pH (2-12). N-termini sequence was obtained by Edman degradation showing higher identity with other Mimosoideae subfamily Kunitz-type inhibitor members. In summary, data here reported indicate the biotechnological potential of PdKI-4 for development of products against insect-pests.

Pneumocystis carinii serologic study in pediatric acquired immunodeficiency syndrome.

Pneumocystis carinii antigen and IgG antibody profiles were prepared on 17 pediatric patients with acquired immunodeficiency syndrome (AIDS) with pneumonia who were examined by a variety of invasive methods for P carinii organisms. Overall, the accuracy of the antigen assay in invasively examined pediatric patients with AIDS with pneumonia was 94% (sensitivity, 100%; specificity, 90%), as antigen and invasive test results agreed in 16 of 17 patients. No statistically significant differences in IgG titer were observed between controls and patients invasively examined for P carinii, whether the organism was observed in the specimen or not. Since 38% of all serum samples referred were derived from "blood-borne" cases of AIDS, including patients who contracted AIDS as a result of both transfusion and hemophilia A, this suggests that P carinii pneumonia or P carinii pneumonia- like pneumonias may be more common in these individuals.