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Biomedical subjects

J Baxter

Publications and source records attributed to J Baxter.

At least 109 records · Page 6Linked to original sources
PubMed1983

[In vitro infestation of human hepatocytes by sporozoites of Plasmodium vivax: schizogony and liberation of merozoites capable of infesting human erythrocytes].

Human hepatocytes obtained by perfusion of a liver biopsy fragment, were infected in vitro with Plasmodium vivax sporozoites raised in Anopheles stephensi. On day 7 of culture, numerous hepatocytic schizonts ranging in size from 5 to 35 micrometers were observed. The schizont maturation was complete and led to the release of invasive merozoites as shown by in vitro infestation of human red cells layered on the hepatocytes cultures.

Animals↗
PubMed1982

Neuron specific in vitro cytotoxicity of sera from patients with amyotrophic lateral sclerosis.

Sera from patients with amyotrophic lateral sclerosis (ALS) were assayed for a neuron-specific cytotoxic effect on long-term organized cultures of neonatal mouse anterior horn segments. Blind studies show that ALS sera when incorporated into the culture media have a greater degree of antineuronal toxicity than sera from patients with other neurological diseases or from family members of ALS patients.

Amyotrophic Lateral Sclerosis↗
PubMed1980

Alkyl glycoside detergents: a simpler synthesis and their effects on kinetic and physical properties of cytochrome c oxidase.

Octyl glucoside is an effective, nonionic, solubilizing agent for membrane proteins with the advantage of ease of removal by dialysis. In order to study the detergent-sensitive activity of cytochrome c oxidase, we chose this detergent because of its simple structure and the possibility of synthesizing analogues to test the structural dependence of the detergent specificity. A procedure was therefore developed that facilitates large-scale preparation of octyl glucoside and related alkyl glycosides, improving on previous methods by eliminating crystallization steps and employing a one-step purification of the final product on Dowex 1. This new purification procedure is particularly important for achieving the level of purity required to obtain the disaccharide, longer alkyl chain detergents in soluble form. Of the alkyl glycosides prepared (octyl beta-D-glucopyranoside, octyl beta-D-lactopyranoside, dodecyl beta-D-lactopyranoside, dodecyl beta-D-cellobiopyranoside, and dodecyl beta-D-maltopyranoside), lauryl (dodecyl) maltoside was found to be the most successful as an activator of purified beef and Neurospora cytochrome oxidase, giving two- to tenfold higher activities than octyl glucoside and other commercially available detergents, Tween-20 and Triton X-100. Kinetic studies using two different steady-state assay systems indicate that the activity changes are not the result of altered binding of the substrate but rather reflect a detergent effect on the state of association of the enzyme (as a monomer, dimer, or polymer) as well as on its intrinsic activity. By gel filtration procedures, lauryl maltoside and octyl glucoside were found to exist as monodisperse populations of micelles of 50 000 and 8000 daltons, respectively. The small uniform micelles and chemically well-defined structures of lauryl maltoside and octyl glucoside make them superior to other nonionic detergents for the study of membrane proteins in general and cytochrome oxidase in particular, since its activity in lauryl maltoside most closely approaches that of the physiological state.

Animals↗
PubMed1980

The relationships of spatial ability and sex to formal reasoning capabilities.

The relationships of spatial ability and sex to performance on formal reasoning tasks were examined for a group of 34 male and female college students. It was hypothesized that spatial ability is positively related to formal reasoning task performance which is also related to male superiority on formal reasoning task performance. Results indicated that spatial ability was unrelated to formal reasoning task performance and that sex differences occurred with the balance of task and the pendulum task which suggested that males were superior to females at manifesting the scheme of proportionality and at being able to isolate variables.

Adolescent↗
PubMed1976

Sensory and reflex responses to tooth pulp stimulation in man.

Experiments have been carried out to investigate whether all tooth pulp afferent nerves are capable of producing pain. Monopolar and bipolar stimuli were applied to teeth in human subjects and sensory thresholds determined. EMGs were recorded from the masseter and the anterior digastric muscles. With stimuli up to three times the sensory threshold, no response could be detected in the digastric but at, or just above, the sensory threshold, inhibitory effects were produced in masseter muscle. The latency of the muscle response with bipolar stimulation was 18-22 msec. There was no evidence of stimulus spread to nerves outside the teeth. Bipolar and monopolar stimulation both produced the same sensation but this was not described as painful. It is concluded that some pulpal afferent nerves may not be capable of producing pain, and that the sensory and reflex responses at threshold were probably produced by the same fibres.

Adult↗