Allen Cohen | PubMed Health

PubMed2006

Retrocecal appendix location and perforation at presentation.

Retrocecal appendicitis has been theorized to follow a more insidious course than other anatomic variants. To determine the influence of retrocecal anatomy on clinical course of appendicitis, 200 adult patients treated at a major university medical center with the diagnosis of appendicitis from 2001 to 2004 were retrospectively studied. Computed tomography (CT) scans of adult patients with an ultimate diagnosis of appendicitis were analyzed to determine an association between retrocecal appendix and perforation of the appendix at presentation. A higher perforation rate in the retrocecal group would imply patient delay in presentation from more tolerable symptoms. CT scans were examined for retrocecal location and perforation. No significant association was found between retrocecal anatomy and perforation rates at presentation (chi-square = 2.1, P = 0.15, odds ratio = 1.6, 95% confidence interval [0.8-3.0]). However, the risk of perforation was 60 per cent higher in the retrocecal group. By regression analysis, age and the presence of a fecalith on CT scan were predictors of appendix perforation. Appendix location was not. In this study, we found no significant association between retrocecal appendix anatomy and perforation at presentation.

Adult↗

PubMed2002

Insect feeding mobilizes a unique plant defense protease that disrupts the peritrophic matrix of caterpillars.

Plants frequently respond to herbivorous insect attack by synthesizing defense proteins that deter insect feeding and prevent additional herbivory. Maize (Zea mays L.) lines, resistant to feeding by a number of lepidopteran species, rapidly mobilize a unique 33-kDa cysteine protease in response to caterpillar feeding. The accumulation of the 33-kDa cysteine protease in the maize mid-whorl was correlated with a significant reduction in caterpillar growth that resulted from impaired nutrient utilization. Black Mexican Sweetcorn callus transformed with mir1, the gene encoding the 33-kDa cysteine protease, expressed the protease and growth of caterpillars reared on the transgenic callus was reduced 60-80%. Scanning electron microscopy was used to examine the effect of plant material expressing the 33-kDa cysteine protease on the structure of the caterpillar peritrophic matrix. Because the peritrophic matrix surrounds the food bolus, assists in digestive processes, and protects the caterpillar midgut from physical and chemical damage, disruption of peritrophic matrix may reduce caterpillar growth. The results indicated that the peritrophic matrix was severely damaged when caterpillars fed on resistant maize plants or transgenic Black Mexican Sweetcorn. The accumulation of the 33-kDa cysteine protease in response to caterpillar feeding, and its ability to damage the insect peritrophic matrix, represents an unusual host-plant resistance mechanism that may have applications in agricultural biotechnology.

Animals↗