A Host-Parasitoid Model for Aspidiotus rigidus (Hemiptera: Diaspididae) and Comperiella calauanica (Hymenoptera: Encyrtidae).

The outbreak of the coconut scale insect Aspidiotus rigidus Reyne (Hemiptera: Encyrtidae) posed a serious threat to the coconut industry in the Philippines. In this article, we modeled the interaction between A. rigidus and its parasitoid Comperiella calauanica Barrion, Almarinez, Amalin (Hymenoptera: Encyrtidae) using a system of ordinary differential equations based on a Holling type III functional response. The equilibrium points were determined, and their local stability was examined. Numerical simulations showed that C. calauanica may control the population density of A. rigidus below the economic injury level.

Relationship of endotoxin to tumor necrosis factor-alpha and interleukin-1 beta in children with otitis media with effusion.

Sixty-five middle ear effusions and paired sera from 41 children with chronic otitis media with effusion were assayed for endotoxin and for tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in order to establish whether a correlation exists between the concentrations of endotoxin and of these cytokines. Endotoxin concentration was determined by means of a chromogenic limulus amebocyte lysate assay, and the cytokine concentration by means of a quantitative enzyme-linked immunosorbent assay. Forty percent of the effusions had detectable levels of endotoxin, with a mean concentration of 2.9 +/- 7.8 endotoxin units per milligram of total protein. The mean concentration of TNF-alpha was 1.24 +/- 3.1 pg/mg total protein, and that of IL-1 beta was 18.79 pg/mg total protein. A strong, statistically significant correlation exists between the concentrations of endotoxin and TNF-alpha (r = .89) and IL-1 beta (r = .72). The data indicate that endotoxin may contribute to the pathogenesis of chronic otitis media with effusion by stimulating the sustained production of TNF-alpha and IL-1 beta in the middle ear.

Relative immunogenicity and efficacy of two synthetic chimeric peptides of fimbrin as vaccinogens against nasopharyngeal colonization by nontypeable Haemophilus influenzae in the chinchilla.

The OMP P5-homologous fimbriae of nontypeable Haemophilus influenzae (NTHi) are an adhesin and a virulence factor for otitis media in chinchilla models. We synthesized two peptides (LB1 and LB2) which incorporate determinants of the fimbrial subunit co-linearly synthesized with a "promiscuous" T-cell epitope from the fusion protein of measles virus. Sera obtained from immunized rabbits and chinchillas demonstrated significant reciprocal titers against both the homologous peptide and isolated fimbrial protein. Antisera also immunolabeled native fimbriae of whole unfixed NTHi. Immunization with LB1 or fimbrin resulted in elimination of NTHi from the chinchilla nasopharynx 2-3 weeks earlier than controls, respectively.

The effect of antibiotic treatment on the release of endotoxin during nontypable Haemophilus influenzae-induced otitis media in the chinchilla.

The gram negative bacteria, nontypable Haemophilus influenzae (NTHi) was used to induce otitis media in a total of 18 chinchillas. Three days post-inoculation, three cohorts of 6 chinchillas each were treated daily for four days with either ceftriaxone, chloramphenicol, or diluent without antibiotics. Middle ear fluid (MEF) was obtained daily, assayed for endotoxin content by means of the chromogenic limulus amebocyte lysate assay, and concentration of the NTHi/mL MEF determined by standard plate count. The endotoxin concentration per mL MEF from both the antibiotic treated cohorts decreased during the observation period, but increased in the MEF of the untreated control group. The data indicate that, unlike the dramatic increase in endotoxin concentration, after antibiotic treatment in the cerebrospinal fluid (CSF) during experimental Haemophilus influenzae-induced meningitis, there is no demonstrable sustained release of endotoxin in the middle ear subsequent to antibiotic treatment during experimental otitis media.

Growth factors during endotoxin-induced otitis media.

The presence of growth factors in the middle ear fluid was examined during lipopolysaccharide-induced otitis media (OM) in the chinchilla. There was a progressive significant increase in the proliferative activity detected in the LPS-free MEF by five days in culture. We conclude that lps indirectly mediates hyperproliferative changes in the middle ear during OM by inducing growth factors.

Adenovirus serotype 1 does not act synergistically with Moraxella (Branhamella) catarrhalis to induce otitis media in the chinchilla.

A chinchilla model of otitis media in which adenovirus compromise of the tubotympanum facilitates the subsequent induction of middle ear disease was used to investigate Moraxella (Branhamella) catarrhalis pathogenesis. Intranasally inoculated M. catarrhalis did readily colonize the nasopharynx of this host; however, despite evidence of viral infection and tubotympanal compromise, M. catarrhalis did not induce culture-positive otitis media in this model.