Viral etiology of obscure splenomegaly in Egyptian children

Fifty seven Egyptian children aged 1.5 to 9.5 years with mild splenomegaly (less than 3 cm below the costal margin) were screened for antibodies against the three common viruses of the Herpes group: Cytomegalovirus (CMV), Epstein-Barr (EB) and Herpes type 1 virus. A group of 57 healthy children were studied similarly. All patients were subjected to a comprehensive laboratory and clinical work up to exclude any hematological, metabolic or malignant etiology for the splenomegaly. Splenic aspirates from five cases were examined histologically and by immunohistochemistry for the antigens of CMV. Only primary or reactivation of CMV might be considered a cause of splenomegaly, as there was a statistically significant increase in the prevalence of IgM antibodies to CMV in the patients compared to normal controls (63% of patients and 19.4% of controls had IgM antibodies, P less than 0.001; 68.3% of patients and 54% of controls had IgG antibodies, P is insignificant). An almost equal proportion of children with and without splenomegaly had antibodies to EB-Viral Capsid Antigen (EBVCA) both IgG and IgM. (28% of cases and 33% of controls had IgM antibodies; 26% of patients and 21% of controls had IgG antibodies). A role of Epstein-Barr viral infection could not be ruled out in these patients. There was a higher prevalence of antibodies to Herpes type 1 virus in asymptomatic controls than in children with splenomegaly. (10% of patients and 43% of controls had IgM antibodies, 10.6% of patients and 38% of controls had IgG antibodies).     

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 °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.     

The composition of urinary stones in the Sudan

Seventy-eight urinary stones from the Sudan were analysed quantitatively; 75.6% of upper urinary tract (UUT) stones and 37.8% of lower tract (LUT) stones were composed of pure calcium oxalate monohydrate. The composition of adult UUT stones in the Sudan is almost identical to that of similar stones from Leeds except that the former contain much more calcium oxalate and much less calcium phosphate. A smaller proportion of adult LUT stones from the Sudan contain magnesium ammonium phosphate and a larger proportion contain uric acid/urate than similar stones from Leeds. Juvenile LUT stones from the Sudan probably contain more calcium oxalate and less uric acid/urate than juvenile bladder stones in some other developing countries.     

Novel breathing motion model for radiotherapy

PURPOSE: An accurate model of breathing motion under quiet respiration is desirable to obtain the most accurate and conformal dose distributions for mobile lung cancer lesions. On the basis of recent lung motion measurements and the physiologic functioning of the lungs, we have determined that the motion of lung and lung tumor tissues can be modeled as a function of five degrees of freedom, the position of the tissues at a user-specified reference breathing phase, tidal volume and its temporal derivative airflow (tidal volume phase space). Time is an implicit variable in this model. METHODS AND MATERIALS: To test this hypothesis, a mathematical model of motion was developed that described the motion of objects p in the lungs as linear functions of tidal volume and airflow. The position of an object was described relative to its position -->P0 at the reference tidal volume and zero airflow, and the motion of the object was referenced to this position. Hysteresis behavior was hypothesized to be caused by pressure imbalances in the lung during breathing and was, in this model, a function of airflow. The motion was modeled as independent tidal volume and airflow displacement vectors, with the position of the object at time t equal to the vector sum -->rP(t) = -->rv(t) + -->rf(t) where -->rv(t) and -->rf(t) were displacement vectors with magnitudes approximated by linear functions of the tidal volume and airflow. To test this model, we analyzed five-dimensional CT scans (CT scans acquired with simultaneous real-time monitoring of the tidal volume) of 4 patients. The scans were acquired throughout the lungs, but the trajectories were analyzed in the couch positions near the diaphragm. A template-matching algorithm was implemented to identify the positions of the points throughout the 15 scans. In total, 76 points throughout the 4 patients were tracked. The lateral motion of these points was minimal; thus, the model was described in two spatial dimensions, with a total of six parameters necessary to describe the 30 degrees of freedom inherent in the 15 positions. RESULTS: For the 76 evaluated points, the average discrepancy (the distance between the measured and prediction positions) of the 15 locations for each tracked point was 0.75 +/- 0.25 mm, with an average maximal discrepancy of 1.55 +/- 0.54 mm. The average discrepancy was also tabulated as a fraction of the breathing motion. Discrepancies of <10% and 15% of the overall motion occurred in 73% and 95% of the tracked points, respectively. CONCLUSION: The motion tracking algorithms are being improved and automated to provide more motion data to test the models. This may allow a measurement of the motion-fitting parameters throughout the lungs. If the parameters vary smoothly, interpolation may be possible, yielding a continuous mathematical model of the breathing motion throughout the lungs. The utility of the model will depend on its stability as a function of time. If the model is only robust during the measurement session, it may be useful for determining lung function. If it is robust for weeks, it may be useful for treatment planning and gating of lung treatments. The use of tidal volume phase space for characterizing breathing motion appears to have provided, for the first time, the potential for a patient-specific mathematical model of breathing motion.