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Biomedical subjects

S L Brenner

Publications and source records attributed to S L Brenner.

42 records · Page 3Linked to original sources
PubMed1975

Detection of Clostridium botulinum toxin by local paralysis elicited with intramuscular challenge.

Clostridium botulinum toxin can be identified by a characteristic, acute local paralysis that follows its injection into the gastrocnemius ("calf" muscle) of mice. The local botulism can be elicited with slightly less than one-tenth the toxin amount that is needed to kill mice by the intraperitoneal (i.p.) challenge route. The practical sensitivities of the intramuscular (i.m.) versus i.p. tests are about equal, however, because maximum sample volume injectable i.m. is 0.1 ml as compared to the 0.5-ml range that can be given i.p. i.m. injection of 10 or more mouse i.p. mean lethal doses causes paralysis in about 1 h, and an i.m. injection of about 0.5 i.p. mean lethal doses causes paralysis in 3 to 4 h. Toxin neutralization by homologous type of antitoxin only can be demonstrated with an incubated mixture of toxin and antitoxin. Although not as convenient as the i.p. method for routine use to detect botulinum toxin, the i.m. method has characteristics which could make it a useful supplement to the presently accepted i.p. procedure.

Animals↗
PubMed1974

A physical method for deriving the electrostatic interaction between rod-like polyions at all mutual angles.

The screened Coulomb interaction between polyelectrolyte cylinders immersed in an ionic bath is examined. The electrostatic force and torque acting between a pair of unlike rods is formulated for all separations in which the electrostatic potential on some dividing surface between rods can be written as a linear superposition of isolated cylinder potentials. (The surface potential on the rods themselves may be much higher than that permitted by a superposition approximation.) The mutual energy in the case of skewed rods is found to be exponential in separation and proportional to 1/sin theta where theta is the twist angle of one rod relative to the other. Rods with similar charge repel each other with a torque acting to make the rods perpendicular while rods of opposite charge attract with the parallel arrangement preferred.

Binding Sites↗
PubMed1973

Force balances in systems of cylindrical polyelectrolytes.

A detailed analysis is made of the model system of two parallel cylindrical polyelectrolytes which contain ionizable groups on their surfaces and are immersed in an ionic bathing medium. The interaction between the cylinders is examined by considering the interplay between repulsive electrostatic forces and attractive forces of electrodynamic origin. The repulsive force arises from the screened coulomb interaction between the surface charge distributions on the cylinders and has been treated by developing a solution to the linearized Poisson-Boltzmann equation. The boundary condition at the cylinder surfaces is determined as a self-consistent functional of the potential, with the input consisting of the density of ionizable groups and their dissociation constants. It is suggested that a reasonably accurate representation for the form of the attractive force can be obtained by performing a pairwise summation of the individual interatomic forces. A quantitative estimate is obtained using a Hamaker constant chosen on the basis of rigorous calculations on simpler systems. It is found that a balance exists between these repulsive and attractive forces at separations in good agreement with those observed in arrays of tobacco mosaic virus and in the A band myosin lattice in striated muscle. The behavior of the balance point as a function of the pH and ionic strength of the bathing medium closely parallels that seen experimentally.

Electrolytes↗
PubMedDate not supplied

Anterior shoulder instability in weight lifters.

Occult instability is recognized as a major cause of shoulder dysfunction in throwing athletes. Few studies have characterized the findings of occult instability in nonthrowers. The purpose of this study was to examine shoulder instability in a group of weight lifters. The symptoms, physical findings, and results of treatment for 23 shoulders in 20 athletes are presented. All athletes presented with a complaint of progressive inability to perform exercises with the upper extremity in the abducted, externally rotated position (the "at-risk" position) because of pain. One hundred percent of the athletes experienced posterior shoulder pain when the shoulder was placed in forced abduction and external rotation. Thirteen shoulders in 10 patients responded to conservative management including aggressive rehabilitation and modification of technique to avoid the at-risk position. The other 10 shoulders, which did not respond to conservative treatment, required surgical treatment to alleviate the symptoms. All 20 patients have successfully returned to their previous weight lifting activities.

Adolescent↗