Genetic Characterization of Hydatid Cysts of Different Intermediate Hosts.

Cystic echinococcosis is an important cosmopolitan parasitic zoonosis that causes public health and economic problems in Egypt. The present study was undertaken to identify genotypes of hydatid cyst (HC) DNA isolated from different animal isolates and to identify the genotype of secondary hydatid cysts (HCs) developed in rabbits experimentally infected with camel HC for detection of any genetic mutation. In the present study, we extracted DNA from the germinal layers of 8 HCs collected from 3 camels, 1 cattle, 1 sheep and 3 donkeys in addition to 3 secondary HCs collected from rabbits experimentally infected with camel HC. PCR amplification of the ITS1 gene of all examined samples showed an amplified DNA band at 1115 bp. The partial nucleotide sequences of the ITS1 gene of all isolates were aligned and compared with the reference sequences of the genotypes G1-G8 in GenBank. The camel and rabbit samples were identified as Echinococcus canadensis genotype 6 (G6), while the cattle and sheep samples belonged to E. granulosus sensu stricto (G1). The donkey isolates belonged to E. equines (G4). Alignment of the ITS1 partial nucleotide sequences of the camel HCs and rabbit secondary HCs isolates with the G6 partial nucleotide sequence in GenBank was performed. Both camel HCs and rabbit secondary HCs isolates exhibited the same sequence identity matrix, which indicated the absence of mutation in the rabbit secondary HCs. It can be concluded that camel and rabbit samples were identified as E. canadensis (G6), the cattle and sheep samples belonged to E. granulosus sensu stricto (G1) and donkey isolates belonged to E. equines (G4). No mutation occurred during HCs transmission from camel to rabbit.

Identification of cardiovascular abnormalities in children with empyema thoracis by two-dimensional and Doppler echocardiography.

To our knowledge, echocardiographic assessment of children with empyema has not been reported previously in the literature. Two-dimensional and Doppler echocardiography were performed in 47 children with acute (n = 23) and chronic (n = 24) empyema and 34 control subjects. Echocardiography demonstrated pericardial effusion in 11 of 47 patients (23 percent). Those with acute empyema had significantly thicker pericardium (p < 0.009) than control subjects. Tricuspid regurgitation was present in 21 of 47 patients (45 percent). The mean right ventricular internal dimension in diastole was significantly larger in patients with acute (p < 0.00002) and chronic (p < 0.006) empyema than that of control subjects. The mean tricuspid pressure gradients indicated an elevated mean right ventricular systolic pressure with increased calculated mean pulmonary arterial systolic pressures of children with acute empyema (38.5 +/- 6.4 mm Hg) and chronic (39.8 +/- 5.6 mm Hg) empyema than the normal mean (20 +/- 4 mm Hg). Children with chronic empyema had significantly less mean left ventricular internal dimension in diastole (p < 0.005) and left ventricular internal dimension in systole (p < 0.02) than control subjects. Strikingly, their mean left ventricular mass was also significantly less (p < 0.05) than that of subjects with either acute empyema or control subjects. These results provide baseline data for follow-up of children with acute and chronic empyema.

Nitrogen-fixing nonlegumes in Egypt. I. Nodulation and N2(C2H2) fixation by Casuarina equisetifolia.

This study examines nodulation and some aspects of N2 fixation by Casuarina equisetifolia growing in Egypt. Plants examined were 2 to 10 years of age, and all were nodulated. Nodules varied from young meristematic lobes on lateral roots to clusters occasionally reaching 10 cm in diameter; they had the characteristic features of the Myrica/Casuarina type. Nodules became brown, woody and lost their N2-fixing activities in the late summer months. Acetylene reduction was used to assay nodule activity. Maximum rates of N2(C2H2) fixation were observed at 35 degrees C. Acetylene reduction by excised nodules was linear for 6 hours, then slowly declined and finally ceased after 10 hours. Variations in N2(C2H2) fixation rates due to season and time of day were also examined. Active fixation was recorded throughout different seasons of the year, except in the late summer months. Diurnal fluctuations showed that N2(C2H2) fixation was higher at night than during the day or afternoon. The results are discussed and compared to the findings of other investigators.

Characterization of nitrogen-fixing (C2H2-reducing) Bacillus species from Egyptian soils.

The characteristics of ten N2(C2H2)-fixing Bacillus strains, isolated from Egyptian soils, were investigated. The isolates were not completely identical to any of the described species in the 8th Edition of BERGEY's Manual. However, two strains were closely related to B. cereus, five strains were tentatively characterized as B. licheniformis and three strains with swollen sporangia and thick-walled endospores shared their main characteristics with B. circulans. A comparison between these bacilli and other known nitrogen-fixing Bacillus species revealed major differences in culture characteristics and C2H2-reducing activities. This suggests that the Bacillus isolates described here are new nitrogen-fixing bacteria.

Salt tolerance of Rhizobium species in broth cultures.

Salt tolerance of five rhizobia strains was examined in broth cultures. Five levels of NaCl concentration were used and the optical density was taken as a measure for the vigour of bacterial growth. Rhizobium leguminosarum and R. meliloti were tolerant to high levels of salinity and growth curves in saline broth showed a similar pattern to the control level. Rhizobium japonicum, cowpea Rhizobium, and R. trifolii were intolerant to salt and showed a strong growth retardation with increasing salt concentration. Growth was inhibited at high levels of salinity. It is suggested that rhizobia sensitivity to salts may be partly responsible to the inhibition of nitrogen fixation by legumes growing under salt stress.

Eco-physiological studies on desert plants : VIII. Root penetration of Leptadenia pyrotechnica (Forsk.) Decne. in relation to its water balance.

1. Leptadenia pyrotechnica (Forsk.) Decne. is a leafless tree growing under, adverse arid conditions in the valleys of the Eastern Desert in Egypt. 2. The plant cover in areas inhabited by this species is very low and amounts to only 1% in some localities. In such an open vegetation competition between roots is lacking and each root system monopolizes a huge volume of soil. 3. The root system of a small Leptadenia bush penetrates to a depth of 11.5 m and has a lateral extension of 10 m. The root system exploits about 850 m3 of soil. The distribution of the roots and their branching is closely related to the availability of the soil moisture in the different strata. 4. The available soil moisture is not uniform throughout the whole profile. Depending on the average available soil moisture at the different depths, the total available moisture in the soil volume occupied by the root system of Leptadenia bush is found to be about 23000 kg. 5. The annual water output by the studied bush is found to be 5700 kg. This means that the available water in the soil occupied by the root system is sufficient to supply the plant for a period of four years without replenishment by rainfall. 6. The present study shows that the plant can live safely for several years under the severe conditions of the desert. The plant possesses some characteristics which help it to keep its water balance positive through increased absorption.