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R H Warren

Publications and source records attributed to R H Warren.

41 records · Page 3Linked to original sources
PubMed1968

The effect of colchicine on myogenesis in vivo in Rana pipiens and Rhodnius prolixus (Hemiptera).

The effect of colchicine on myogenesis in vivo has been studied in the regenerating tadpole tail of the frog, Rana pipiens, and in the abdominal molting muscles of a blood-sucking bug, Rhodnius prolixus Stål. Colchicine is shown to disrupt microtubules in the differentiating muscle cells of both these organisms. The disruption of microtubules is correlated with a loss of longitudinal anisometry in the myoblasts and myotubes of the regeneration blastema in the tadpole tail. Before colchicine treatment, the myotubes contain longitudinally oriented myofibrils. After colchicine treatment, rounded, multinucleate myosacs containing randomly oriented myofibrils are present. It is suggested that the primary function of microtubules in myogenesis in the Rana pipiens tadpole is the maintenance of cell shape. The abdominal molting muscles of Rhodnius undergo repeated phases of differentiation and dedifferentiation of the sarcoplasm. However, the longitudinal anisometry of the muscle fibers is maintained in all phases by the attachments of the ends of the fibers to the exoskeleton, and microtubule disruption does not alter cell shape. The orientation of the developing myofibrils is also unaltered, indicating that the microtubules do not directly align or support the myofibrils in this system.

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PubMedDate not supplied

Somatomedin activity in cystic fibrosis and reserpinized rats: possible explanation for growth retardation.

Somatomedin activity in children who have cystic fibrosis is reduced to approximately 50 percent of the levels found in normal children. In contrast, the growth hormone concentration in these patients, both the resting and the stimulated levels, was found to be no different from normal children (17.2 and 18.4 ng per ml, respectively). Reserpinized rats have been proposed as a model for cystic fibrosis. Serum somatomedin activity in rats treated with reserpine (0.50 mg per kg per d x 7 days) was reduced to 30 percent of the levels measured in control rats. Reserpine also decreased radiosulfate incorporation into cartilage glycosaminoglycan (GAGS) in vivo and in vitro. Fasting decreased serum somatomedin activity as well as the concentration of GAGS in rat cartilage. Refeeding for 24 hours restored these parameters to normal. These data suggest that one mechanism for the growth retardation occurring in patients who have cystic fibrosis may be explained by decreased serum somatomedin activity.

Animals↗
PubMedDate not supplied

Chest wall motion in neonates utilizing respiratory inductive plethysmography.

After calibration, respiratory inductive plethysmography can accurately measure breathing patterns noninvasively by transmitting ribcage and abdomen compartment changes caused by ventilation through oscillator circuitry. We measured the breathing pattern of nine quietly awake healthy newborn infants and assessed components reflecting asynchrony, paradoxic motion, and overall phasic relations between ribcage and abdomen compartments. Breathing pattern data (mean +/- SD) on 136 total tidal volume (Vt) breaths revealed: Vt, 14.4 +/- 3.40 ml; frequency, 52.1 +/- 11.5 beats/min; ribcage contribution to Vt, 32.2% +/- 13.4%; maximum compartmental amplitude/Vt, 1.01 +/- 0.01; phase angle, 13.2 +/- 9.50 degrees; inspiratory asynchrony index, 0.26 +/- 0.20 ml2/ml; expiratory asynchrony index, 0.42 +/- 0.3 ml2/ml; and average asynchrony index, 0.34 +/- 0.20 ml2/ml. Results demonstrated a high degree of synchrony between ribcage and abdomen movement during quietly awake breathing. Outward motion of the abdomen preceded that of the ribcage for almost every measured breath.

Abdomen↗