Zinc-induced seizures: a new experimental model of epilepsy

Seizures produced by intracerebral injection of zinc sulfate in rabbits are a new chronic model of experimental epilepsy. The main features of this model are: the animals are easily controlled, the electrocorticogram is conveniently recorded, the endpoints are definite, and the rate of seizure is higher than with other methods. The commonly used antiepileptic drugs, such as phenobarbital (30 mg/kg), diphenylhydantoin (30 mg/kg), nitrazepam (3 mg/kg), and sodium valproate (300 mg/kg), have therapeutic effects in treating this experimental epilepsy, when they are given intravenously. But they can not protect the rabbits from death, except phenobarbital.

Sensation of rotation about a vertical axis with a fixed visual field in different illuminations and in the dark

This paper compares the motion sensations of a subject rotated about a vertical axis for two fixed visual fields (a large peripheral field and a single central spot) and in darkness. Motion sensation is described in terms of threshold, frequency response, and subjective displacement and velocity. The perception of angular acceleration showed significantly lower threshold and reduced latency time for the illuminated presentation. The level of illumination, however, produced no significant difference in threshold. The subjective frequency response, measured by a nulling method, showed a higher gain in the illuminated presentation, particularly at low frequencies and accelerations. With the subject rotating a pointer to maintain a fixed heading during triangular velocity stimuli, subjective displacements showed no difference for all different visual cues. Magnitude estimates of the after-rotation associated with deceleration from a constant velocity showed a quicker rising speed, larger subjective velocity and longer duration in the illuminated presentation. All the results suggest that the oculogyral illusion is principally responsible for producing a lower threshold in the illuminated presentation, although the fixed peripheral visual field tends to reduce reliance upon vestibular signals. At lower intensity rotation stimuli, this effect is especially apparent.

Experimental infection of pregnant sows with porcine enteroviruses

In a series of experiments, SMEDI A--porcine enterovirus serotype 8--was given by intrauterine route to pregnant gilts at intervals between gestation days 0 and 30, and SMEDI C-porcine enterovirus serotype 1--was given to pregnant gilts at intervals between gestation days 30 and 41 to 43. Antibodies were detected in fetuses from groups inoculated at gestation days 30 and 41 to 43, whereas virus was isolated from fetuses only from groups inoculated at gestation days 41 to 43. When inoculated directly into the uterus, embryonic or fetal infection with these viruses was observed regardless of the preinoculation serologic status of the gilts, indicating that maternal antibody had no effect on embryonic or fetal infections after the virus was in the uterus. Intranasal inoculation of SMEDI C caused embryonic or fetal infections in seronegative gilts but not in gilts that carried specific antibody to SMEDI C at the time of exposure. Antibodies in gilts that were seropositive at time of inoculation probably neutralized the virus before it could reach the uterus and thus prevented embryo or fetal infections.

Physarum myosin light chain binds calcium

Myosin from the slime mold Physarum polycephalum contains three sizes of polypeptides: a heavy chain and two light chains, LC-1 and LC-2. Using a simple qualitative test for calcium binding by comparing electrophoretic migration of the polypeptides in sodium dodecyl sulfate (SDS) acrylamide gels in the presence and absence of calcium, we have found that Physarum myosin light chain LC-2 migrates with an apparent molecular weight of 16,900 daltons in the presence of the metal ion chelator ethylene glycol bis (B-aminoethyl ether) N,N'-tetraacetic acid (EGTA). However, if calcium chloride is added to the sample prior to electrophoresis, the apparent molecular weight decreases to 16,100. Lanthanide and cadmium ions, but not magnesium, can substitute for calcium. Because the ionic radii of Ca2+, La3+, and Cd2+ are almost identical, we conclude that Physarum myosin LC-2 possesses a very size-specific binding site for calcium. Physarum myosin LC-1 and the heavy chain give no evidence for binding calcium by this test. Since cytoplasmic streaming in the plasmodium of Physarum requires calcium, our evidence indicates that the calcium-binding property of Physarum myosin LC-2 may be important in regulating the production of force by actomyosin in the ectoplasm. Unexpectedly, the myosin light chain in Physarum capable of binding calcium, LC-2, is the essential light chain, while LC-1 is a member of the regulatory class of myosin light chains [V. T. Nachmias, personal communication]. Until now, essential myosin light chains have not been shown to have high affinity divalent cation binding sites. This means a new version of the myosin-based model for actomyosin regulation by calcium may be required to explain cytoplasmic movement in Physarum, and perhaps in other motile systems involving cytoplasmic myosins as well.

Cephradine in the treatment of infective endocarditis

Ten patients with a mean age of 34.1 years with infective endocarditis (55% of cases due to Staphylococcus aureus) were treated with cephradine. The peak serum levels of cephradine (8-42 microgram/ml) were 3- to 17-fold higher than the minimum inhibitory concentrations of cephradine against pathogenic strains of S aureus (1.2-4 microgram/ml). Patients treated with cephradine became afebrile in 2 to 13 days of therapy, and their white blood cell count returned to a normal level in 3 to 30 days. Cephradine therapy was well tolerated without any incidence of phlebitis. The drug could be administered by three different routes. Cephradine is a useful cephalosporin for treatment of nonenterococcal gram-positive endocarditis in young heroin addicts.

A Method for Optimal Tolerance Selection

This paper introduces and formalizes a method for specifying independent functional tolerances in an optimal least-cost manner. Previous methods have been thwarted by formulation and computational difficulties presented by nontrivial designs. This method is versatile, submits to a diversity of mechanical problems, and relates the production process and cost to process tolerance in the optimization. This tolerance-specification scheme follows Balas’ zero-one algorithm. Generality and efficiency of the method are discussed. Effects of tolerance relaxation on costs are given. Small and large design problems, constructed to satisfy the requirements of the algorithm, show the practical ramifications. The problem is treated with limit, sensitivity, and probability analysis. Widespread adoption of the method throughout industry is encouraged.

Some pharmacological actions of 2,5-dimethoxy-4-ethylamphetamine (DOET) in rats and mice

DOET, like DOM, exhibited pressor action in rats. This increase of blood pressure was blocked by pretreatment with cinanserin. DOET at high doses decreased the spontaneous locomotor activity of mice at the first hour but increased the activity at the second hour; a low dose was less effective. DOET also increased the rectal temperature of rats and this hyperthermic action was suppressed by pretreating the animals with cinanserin or methysergide. These actions of DOET were compared with those of DOM.

Comparative chemistry of 30S ribosomal proteins of Salmonella typhimurium

Individual proteins from the 30S ribosome of Salmonella typhimurium were isolated and compared with their counterparts in Escherichia coli. Amino acid composition data reveal either no significant differences, or only minor differences in a few residues between paired proteins. Tryptic peptide fingerprints were used to amplify any possible differences between protein pairs.