Urine analysis of three rodent species with emphasis on calcium and magnesium bicarbonate

The urine composition of three rodent species, mole rat Spalax ehrenbergi, the golden hamster Mesocricetus auratus and the white rat Rattus norvegicus was studied. These three species represent different degrees of fossoriality. The results show that the urine of the species that show a higher degree of fossoriality, the mole rat and the hamster, contain high values of calcium and magnesium bicarbonates when compared with the white rat. From these results it may be assumed that the mole rat as well as the hamster can use the kidney as a pathway for releasing bicarbonate and carbonate. This mechanism may reduce the CO2 concentration in their hypercapnic environment.     

Effect of position on the mechanical interaction between the rib cage and abdomen in preterm infants.

To determine the influence of body position on chest wall and pulmonary function, we studied the ventilatory, pulmonary mechanics, and thoracoabdominal motion profiles in 20 preterm infants recovering from respiratory disease who were positioned in both the supine and prone position. Thoracoabdominal motion was assessed from measurements of relative rib cage and abdominal movement and the calculated phase angle (an index of thoracoabdominal synchrony) of the rib and abdomen Lissajous figures. The ventilatory and pulmonary function profiles were assessed from simultaneous measurements of transpulmonary pressure, airflow, and tidal volume. The infants were studied in quiet sleep, and the order of positioning was randomized across patients. The results demonstrated no significant difference in ventilatory and pulmonary function measurements as a function of position. In contrast, there was a significant reduction (-49%) in the phase angle of the Lissajous figures and an increase (+66%) in rib cage motion in prone compared with the supine position. In addition, the degree of improvement in phase angle in the prone position was correlated to the severity of asynchrony in the supine position. We speculate that the improvement in thoracoabdominal synchrony in the prone position is related to alterations of chest wall mechanics and respiratory muscle tone mediated by a posturally related shift in the area of apposition of the diaphragm to the anterior inner rib cage wall and increase in passive tension of the muscles of the rib cage. This study suggests that the mechanical advantage associated with prone positioning may confer a useful alternative breathing pattern to the preterm infant in whom elevated respiratory work loads and respiratory musculoskeletal immaturity may predispose to respiratory failure.     

Isolation of viable deletion mutants of Streptomyces actinophage (Pal 6) and their molecular characterization

Summary Deletion mutants of bacteriophage Pal 6 were isolated by successive treatments of either heat (60° C) or pyrophosphate (10 mM). These mutants were characterized by restriction enzyme cleavage analysis. The pyrophosphate resistant clones lost the whole Eco R1 fragment in which the Sal I site is located, as well as an unrelated Hind III fragment. These results show that the region containing the Sal I site in the phage genome is not essential for phage viability. This single Sal I site is therefore suitable as a potential insertion site for DNA cloning. On the other hand, the heat resistant clones that were isolated and characterized do not appear to have detectable deletions as indicated by their Eco R1 DNA digestion pattern.     

The role of Hsp90 in cell response to hyperthermia

(1) Preincubation of SKOV3 human ovarian carcinoma cells with a non-toxic dose of Geldanamycin resulted in exacerbation of hyperthermia-induced cytotoxicity and re-distribution of dying cells toward necrosis. (2) Exposure of primary human ovarian carcinoma cells to mild hyperthermia (42 °C for 2 h) led, after a recovery period of 16 h, to several-fold increase in the levels of Hsp90 and ErbB2, to a moderate decrease in the levels of phospho-Erk1/2, whereas the level of β-catenin appeared to be unchanged. (3) The inhibitors of Hsp90 (Geldanamycin and Novobiocin) significantly affected the cell signaling of heat-pretreated cultures. (4) The results suggest that Hsp90 plays a pivotal role in cell response to hyperthermia. (5) A combination of Hsp90 inhibitors with hyperthermia may considerably increase the efficacy of thermotherapy.     

Alveolar dehiscences and fenestrae in dried south African Negro mandibles

The buccal and lingual roots of 1077 teeth from 100 mandibles of South African Negroes were examined for the presence of dehiscences and fenestrae. All specimens were obtained from cadavers of known sex, tribe, and stated age; 10.5% of teeth were affected. Canines and first premolars were the most common teeth associated with dehiscences and fenestrae. Dehiscences occurred more commonly than fenestrae (1:0.49). The defects were found exclusively in the buccal plate of the alveolar process.     

Juvenile Sandhill Cranes exhibit wider ranging and more exploratory movements than adults during the breeding season

Sandhill Cranes Antigone canadensis exhibit delayed sexual maturity and breeding, and therefore juvenile Cranes searching for suitable territories to occupy have different ecological constraints on movements than adults, which must defend a territory and raise young. We used fine-scale GPS telemetry data to characterize and compare movements of adult and juvenile Cranes near the boundary between two populations in Minnesota, USA, from arrival on natal areas in the spring until staging prior to autumn migration. Juvenile and adult Cranes had marked differences in movement patterns throughout the breeding season. Juveniles were more likely than adults to display long-distance movements: they revisited areas less frequently throughout the breeding season and they had lower average residence times.