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Biomedical subjects

M Tyler

Publications and source records attributed to M Tyler.

54 records · Page 3Linked to original sources
PubMed1981

In vitro release of cholecystokinin octapeptide-like immunoreactivity from rat brain synaptosomes.

Enriched synaptosome fractions prepared by differential centrifugation and ultracentrifugation of homogenates of rat cortex, striatum, thalamus and hypothalamus contained over 65% of the total immunoreactive cholecystokinin octapeptide (CCK-8) in each area. A calcium-dependent release of immunoreactive CCK-8 from these fractions in vitro in response to 2 depolarizing stimuli (60 mM KCl and 75 microM veratrine) has been demonstrated. Released CCK-8 immunoreactivity showed parallelism when dilutions were compared with the CCK-8 dose-response curve and eluted similarly to synthetic CCK-8 on Sephadex G-50 superfine chromatography. These results provide further evidence for a neurotransmitter or neuromodulator role for CCK-8 in brain.

Animals↗
PubMed1980

The purification and characterization of a third storage protein (convicilin) from the seeds of pea (Pisum sativum L.).

A third storage protein, distinct from legumin and vicilin, has been purified from the seeds of pea (Pisum sativum L.). This protein has been named 'convicilin' and is present in protein bodies isolated from pea seeds. Convicilin has a subunit mol.wt. of 71 000 and a mol.wt. in its native form of 290 000. Convicilin is antigenically dissimilar to legumin, but gives a reaction of identity with vicilin when tested against antibodies raised against both proteins. However, convicilin contains no vicilin subunits and may be clearly separated from vicilin by non-dissociating techniques. Unlike vicilin, convicilin does not interact with concanavalin A, and contains insignificant amounts of carbohydrates. Limited heterogeneity, as shown by isoelectric focusing, N-terminal analysis, and CNBr cleavage, is present in convicilin isolated from a single pea variety; genetic variation of the protein between pea lines has also been observed.

Amino Acids↗
PubMed1975

A comparative evaluation of Avitene and gelfoam for hemostasis in experimental canine prostatic wounds.

Microcrystalline collagen has been reported to be an effective hemostatic agent in brain, liver, kidney, etc. This experimental study in dogs and rats shows that microcrystalline collagen is a more effective hemostat in prostatic hemorrhage than is purified gelatin solution. No gross or histologic evidence of tissue damage or calcification was induced by microcrystalline collagen or purified gelatin solution. Wafers of microcrystalline collagen that are placed in rat bladders dissolve and do not induce calculogenesis.

Animals↗
PubMed1974

Potentiation of the antibacterial effect of methenamine by acetohydroxamic acid.

In vitro testing shows nearly all strains of Proteus to be susceptible to methenamine. However, infection by urease-producing bacteria alkalinizes the urine in vivo and prevents generation of formaldehyde, the active metabolite, from methenamine. We have previously shown acetohydroxamic acid (AHA) to be an effective inhibitor of bacterial urease in vitro and in vivo. We now present data obtained by use of static and dynamic in vitro systems, which show that, by preventing urease-induced alkalinization of urine, AHA enables methenamine to exert its antibacterial effect against representative Proteus species.

Drug Synergism↗
PubMedDate not supplied

Selective alteration of sodium channel gating by Australian funnel-web spider toxins.

The actions of potent mammalian neurotoxins isolated from the venom of two Australian funnel-web spiders were investigated using both electrophysiological and neurochemical techniques. Whole-cell patch clamp recording of sodium currents in rat dorsal root ganglion neurons revealed that versutoxin (VTX), isolated from the venom of Hadronyche versuta, produced a concentration-dependent slowing or removal of tetrodotoxin-sensitive (TTX-S) sodium current inactivation and a reduction in peak TTX-S sodium current. In contrast, VTX had no effect on tetrodotoxin-resistant (TTX-R) sodium currents or potassium currents. VTX also shifted the voltage dependence of sodium channel activation in the hyperpolarizing direction and increased the rate of recovery from inactivation. Ion flux studies performed in rat brain synaptosomes also revealed that robustoxin (RTX), from the venom of Atrax robustus, and VTX both produced a partial activation of 22Na+ flux and an inhibition of batrachotoxin-activated 22Na+ flux. This inhibition of flux through batrachotoxin-activated channels was not due to an interaction with neurotoxin receptor site 1 since [3H]saxitoxin binding was unaffected. In addition, the partial activation of 22Na+ flux was not enhanced in the presence of alpha-scorpion toxin and further experiments suggest that VTX also enhances [3H]batrachotoxin binding. These selective actions of funnel-web spider toxins on sodium channel function are comparable to those of alpha-scorpion and sea anemone toxins which bind to neurotoxin receptor site 3 on the channel to slow channel inactivation profoundly. Also, these modifications of sodium channel gating and kinetics are consistent with actions of the spider toxins to produce repetitive firing of action potentials.

Amino Acid Sequence↗
PubMedDate not supplied

Outcomes of family-centered residential treatment.

This article describes a family-centered residential treatment model and presents results from a quasiexperimental study examining its effectiveness in achieving permanency outcomes for children. Greater postdischarge stability was achieved for participants in the family-centered program than in the agency's standard residential treatment service. Implications for child welfare policy and practice are highlighted.

Adolescent↗