Elongation and constriction in cell division

The deformation of a constant reaction ellipsoidal cell by diffusion and constant surface tension forces is studied. The critical size of a spherical cell at which it becomes unstable to ellipsoidal deformations is found to be the same as that obtained previously by N. Rashevsky from energy considerations. It is shown that such a cell once unstable will elongate to a finite amount, and that it will tend to constrict in the center and round up at the poles.     

Mechanisms of seizure control mediated by gamma-aminobutyric acid: role of the substantia nigra

The substantia nigra has been identified as a critical site at which gamma-aminobutyric acid (GABA) agonist drugs act to reduce susceptibility to a number of types of experimentally induced generalized seizures. Moreover, the ability of systemically administered GABA-elevating agents to protect against maximal electroshock seizures is directly correlated with an increase in GABA specifically in the nerve-terminal compartment of substantia nigra. The significance of these findings is discussed in terms of the role of specific nigral synapses for the control of seizure propagation. Evidence from lesion studies, as well as studies with opiates and substance P analogs, further supports the hypothesis that Inhibition of nigral efferents reduces susceptibility to generalized seizures. Inhibition of nigral outflow causes a decreased sensitivity to chemoconvulsants without precluding the animal's ability to exhibit any or all of the motor components of a seizure. We therefore propose that nigral outputs are capable of facilitating seizure propagation and can function as a gating mechanism for the generalization of convulsive activity.     

Chromosomal location in wheat of the genes coding for the acyl carrier proteins I and III

Communicated by J.W. Snape     

Clinical and electromyographic effects of biofeedback training in mandibular dysfunction

Twenty patients with mandibular dysfunction, 10 acute and 10 chronic, were trained with electromyographic biofeedback from either m. masseter or m. frontalis area. The electromyographic activity in both muscle areas were recorded during six training sessions. The mean electromyographic activity decreased significantly within the sessions for both muscle areas, progressively more often for the m. masseter area. The activity did not decrease significantly between sessions for any muscle area. The clinical and subjective symptoms of mandibular dysfunction improved significantly after the training. No differences, electromyographically or clinically, among acute, chronic, m. masseter area, or m. frontalis area feedback patients could be observed. No correlation between decrease in electromyographic activity and symptoms could be established. Since a simplistic neuromuscular learning model for biofeedback training gains little support from these results, alternative views are discussed.     

SARS-CoV-2 variant B.1.1.7 is susceptible to neutralizing antibodies elicited by ancestral spike vaccines

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Carbon monoxide excretion as an index of bilirubin production in rhesus monkeys

The role of increased heme catabolism in neonatal hyperbilirubinemia was investigated in rhesus (Macaca mulatta) neonates through the measurement of carbon monoxide excretion rates (VECO), blood carboxyhemoglobin content (HbCO), and plasma bilirubin concentrations. Neonatal values were compared to those of adult rhesus monkeys. These indices of bilirubin production responded appropriately to administration of NEM-damaged erythrocytes and tin protoporphyrin. Our results indicate that VECO measurements are a valid index of changes in bilirubin production in the newborn rhesus monkey.     

Therapeutic efficacy of rifampin in newly detected pulmonary tuberculosis

A comparison was made of the therapeutic efficiency and tolerance of rifampin-based regimens and that of the standard triple-drug combination in the treatment of 92 newly diagnosed cases of pulmonary tuberculosis. The three drug regimens investigated were: A, rifampin-INH; B, rifampin-INH-streptomycin; and C, INH-PAS-streptomycin. Therapeutic progress was measured in terms of sputum conversion on culture and microscopy. The rifampin combinations produced a somewhat earlier sputum conversion. With regimens containing this potent antibiotic the phenomenon of microscopically-positive but culture-negative specimens was more frequently observed. The tolerance exhibited to the rifampin regimens was far greater than that to the conventional triple-drug combination. Nevertheless, periodic laboratory examinations are essential during rifampin therapy for safe utilization of the drug. An incidental finding of this study was the increase in primary resistance to streptomycin particularly among recent immigrants to Canada.