Various physiological and biochemical characters of a leafthe slightly affected P n of the developing leaf was associated change with stages of its ontogeny. It is likely that the with the almost unchanged photochemical efficiency of photophotosynthetic functions of leaves of different ontogeny have system II (F v /F m ) and the quantum yield of photosystem II different levels of heat tolerance. This study was initiated to electron transport. The chlorophylls a and b were degraded by analyze the photosynthetic heat tolerance of fully-developed, heat stress; the degradation was pronounced in the developed nearly-developed (more than 2/3 expanded) and developing leaves. As a result of heat stress, the antheraxanthin and zeaxanthin of the xanthophyll cycle accumulated in both the (10-12 cm visible) leaves of two maize genotypes, F223 and nearly-developed and developed leaves but not in the develop-F250. The results indicate that the photosynthetic CO 2 assimilation rate (P n ) of developing leaves was less affected by heat ing leaves. Injury to the plasma membrane due to heat stress stress (42°C in the dark for 90 min) than that of developed was much less severe in developing leaves than that in the leaves. The impaired P n recovered within 24 h in the develop-developed leaves. From the physiological characters which we determined it would appear that the P n functions of the ing leaves, while the P n of developed and nearly-developed developing leaves are more resistant to heat stress than those leaves did not reach the non-stress level, even after 72 h. The of nearly-developed and developed leaves. P n of the developed leaves of genotype F250 was less affected by heat stress than that of genotype F223. After heat stress,

Diagnosis of tuberculosis (TB) in children is difficult because symptoms are often nonspecific or absent in infected children, diagnostic specimens are difficult to obtain from younger children, and >50% have negative TB cultures. Thus, there is an urgent need for improved diagnosis of pediatric TB. This study aimed to evaluate the diagnostic value of a new serological method, the ALS (antibodies in lymphocyte supernatant) assay, for the diagnosis of active TB in children with clinically identified TB. The ALS test is based on the concept that antigen-specific plasma cells are present in the circulation only at times of acute infection and not in latency. A cross-sectional study of pediatric patients (age range, 11 to 167 months) who were clinically identified as TB (n ‫؍‬ 58) or non-TB (n ‫؍‬ 16) patients was conducted, and they were monitored for 6 months. Healthy children (n ‫؍‬ 58) were enrolled as controls. Spontaneous release of TB antigen-specific antibodies by in vitro-cultured, unstimulated peripheral blood mononuclear cells was assessed by an enzyme-linked immunosorbent assay using Mycobacterium bovis bacillus Calmette-Guérin ( According to World Health Organization (WHO) estimates, about 1 million children annually develop tuberculosis (TB) worldwide, accounting for about 11% of all TB cases (25,42,48). Bangladesh ranks 6th among the 22 high-TB-burden countries in the world; about 45% of its population is tuberculin positive at the age of 14 years (22, 48). Childhood TB is often not considered a priority by national TB control programs, because children acquire Mycobacterium tuberculosis infections from adults and do not contribute to disease transmission. However, failure to identify and treat TB in children can lead to death in a majority of Ͻ3-year-old children (14, 23).TB-infected children are often asymptomatic, and bacteriologic confirmation is rare, due to the difficulty of obtaining specimens (8, 31). Most pediatric TB cases are diagnosed using a combination of clinical and epidemiological features, which include characteristic chest radiographs (18), reactive tuberculin skin tests (TST), and a history of contact with active TB cases (31, 34); computed tomography and bronchoscopy are performed in industrialized countries (19). In areas where TB is endemic, most of the population acquires TB infection during childhood, and transmission is not restricted to the household (32,46). This situation limits the diagnostic contribution of documented household exposure and positive TST (10,47). Interpretation of TST reactivity is further complicated by the high prevalences of Mycobacterium bovis BCG vaccination and malnutrition. Radiographic changes in children can be quite variable (18). Serodiagnostic methods are generally low in sensitivity and specificity, especially for children, and seroreactivity data for pediatric TB are also limited (3,4,12,20,26,41). Recent studies evaluating multiple antigens by an enzymelinked immunosorbent assay (ELISA) or a multiantigen print immunoassay for the serodetect...